2245H Sub-Woofer Project

[Val]

Last year I bought a new-old-stock 2245H off the bay. Next week I will begin construction of a sub-woofer box. I will build it to match the speakers that I built a few years back (pictured here) with the help of this forum (http://audioheritage.org/vbulletin/showthread.php?t=7140).

My wife, now completely converted to vintage JBL sound, has agreed to a 12.8 cubic feet box as long as it is aesthetically pleasing. The idea is this: get rid of our existing 20 year old entertainment center, build a low and wide sub, build a matching equipment rack to ride on top of the sub and top with a new 46" (or bigger) LCD TV. Everybody wins.

I've got it all penciled out. The sub will be made of 1" MDF and have external measurements of 64"W x 23"H x 19"D. This yields 12.8 cu ft internal. I'm planning on using 2 each 4" ports. WinISD calculates 3.22" long tunes to 30 Hz and 5.26" long tunes to 26 Hz. Once I get it built I'll play around with tuning.

My biggest concern is that the long and narrow shape of the box will have standing wave issues at certain frequencies. I do plan to brace the heck out of the box.

I'll scan in my sketches soon.

I welcome design comments and suggestions.

[4313B]

The idea is this: get rid of our existing 20 year old entertainment center, build a low and wide sub, build a matching equipment rack to ride on top of the sub and top with a new 46" (or bigger) LCD TV.Been there.
My biggest concern is that the long and narrow shape of the box will have standing wave issues at certain frequencies.Calculate the frequency of the lowest standing wave and if it is an octave or two above your crossover frequency then it should be "ok".

Alot of subs are cubes which is a total no but they do it anyway because it is minimal material and they cross them over low enough for the standing waves to be reasonably attenuated.

[duaneage]

You could use staggered walls inside the box to add bracing and break up the dimensions to prevent standing waves. Do some testing with loose boards and a signal generator to find the best place to put them.

[Val]

Been there.Calculate the frequency of the lowest standing wave and if it is an octave or two above your crossover frequency then it should be "ok".

Currently I'm running a cheapo Sony AV receiver (STR-DE595) which has a sub-out. I have looked but cannot find the sub-crossover frequency.

Looking at it another way, and, if I have my math right, the frequency of the wave that fits in the 62" internal width is 217Hz. Halving that is about 109 Hz. Which could be a problem as I imagine the sub crossover is higher than that.

[Val]

You could use staggered walls inside the box to add bracing and break up the dimensions to prevent standing waves.

If I put in two staggered walls then certainly there would be shorter wave lengths between the walls which is good. But doesn't the wave travel the "S" shape around the staggered walls and so a longer wave length is created?

[Loren42]

I ran your numbers through BassBox Pro and did not get the same port length you cited for 30Hz.

However, the real problem is not port length, but vent speed. Two 4" vents yield a vent speed of almost 30 m/s. That is almost twice the maximum speed you should design for.

Using a 12.8 cubic foot internal volume you should use two 6" diameter vents (internal diameter) that are 6.624" long. I would flare both ends.

The cabinet is tuned to 30 Hz and has an F3 of 30.52 Hz. Vent speed is a comfortable 12 m/s.

If you choose a 26 Hz Fb, then the ports will be 11.18" long and the F3 will be 30.99 Hz.

The standing wave is not likely to be a real issue if you stuff the box correctly. Rock wool is a cheap and effective tool to cut standing waves and internal coloration.

One thing you do not want to do is electronically assist this box below the Fb. Plots show that with 300 watts applied your cone excursion exceeds xmax at about 24 Hz for the cabinet with an Fb of 30 Hz and xmax is exceeded at 20 Hz for the 26 Hz tuned box.

300 Watts is not a lot of power, but your SPL level will be at 112 dB at those frequencies when you reach xmax, which should rock very well. However, any frequencies lower than 20 or 24 Hz will be much worse as far as exceeding xmax. A low cutoff filter may be a good idea.



Last year I bought a new-old-stock 2245H off the bay. Next week I will begin construction of a sub-woofer box. I will build it to match the speakers that I built a few years back (pictured here) with the help of this forum (http://audioheritage.org/vbulletin/showthread.php?t=7140).

My wife, now completely converted to vintage JBL sound, has agreed to a 12.8 cubic feet box as long as it is aesthetically pleasing. The idea is this: get rid of our existing 20 year old entertainment center, build a low and wide sub, build a matching equipment rack to ride on top of the sub and top with a new 46" (or bigger) LCD TV. Everybody wins.

I've got it all penciled out. The sub will be made of 1" MDF and have external measurements of 64"W x 23"H x 19"D. This yields 12.8 cu ft internal. I'm planning on using 2 each 4" ports. WinISD calculates 3.22" long tunes to 30 Hz and 5.26" long tunes to 26 Hz. Once I get it built I'll play around with tuning.

My biggest concern is that the long and narrow shape of the box will have standing wave issues at certain frequencies. I do plan to brace the heck out of the box.

I'll scan in my sketches soon.

I welcome design comments and suggestions.

[4313B]

The nice thing about the B460 or 4645 (2245H version tuned to 25 Hz, not the 2245H version tuned to 30 Hz) with the BX63/BX63A is that one only needs 8 cubic feet tuned to 25 Hz to get rock solid response to 25 Hz and the low cutoff filter is built right in.

[Loren42]

The nice thing about the B460 or 4645 (2245H version tuned to 25 Hz, not the 2245H version tuned to 30 Hz) with the BX63/BX63A is that one only needs 8 cubic feet tuned to 25 Hz to get rock solid response to 25 Hz and the low cutoff filter is built right in.

That is an electronically assisted cabinet?

[grumpy]

... electronically assisted alignment, yes.

[4313B]

Yes, all you do is take a typical 12 dB/octave high pass cutoff filter and skew the Q so it has a bump at the tuning frequency of the vented box.

B460 (http://audioheritage.org/vbulletin/showthread.php?t=4557)

What's the cost? A reduction of enclosure real estate by four to six cubic feet and a few more electronic parts in the form of a BX63/BX63A resulting in a shift in alignment from quasi-third order to quasi-fifth order yielding increased group delay which most people couldn't care less about anyway.

[Val]

I ran your numbers through BassBox Pro and did not get the same port length you cited for 30Hz.

However, the real problem is not port length, but vent speed. Two 4" vents yield a vent speed of almost 30 m/s. That is almost twice the maximum speed you should design for.

Using a 12.8 cubic foot internal volume you should use two 6" diameter vents (internal diameter) that are 6.624" long. I would flare both ends.

The cabinet is tuned to 30 Hz and has an F3 of 30.52 Hz. Vent speed is a comfortable 12 m/s.

If you choose a 26 Hz Fb, then the ports will be 11.18" long and the F3 will be 30.99 Hz.

The standing wave is not likely to be a real issue if you stuff the box correctly. Rock wool is a cheap and effective tool to cut standing waves and internal coloration.

One thing you do not want to do is electronically assist this box below the Fb. Plots show that with 300 watts applied your cone excursion exceeds xmax at about 24 Hz for the cabinet with an Fb of 30 Hz and xmax is exceeded at 20 Hz for the 26 Hz tuned box.

300 Watts is not a lot of power, but your SPL level will be at 112 dB at those frequencies when you reach xmax, which should rock very well. However, any frequencies lower than 20 or 24 Hz will be much worse as far as exceeding xmax. A low cutoff filter may be a good idea.

Thank you for running those numbers on bb and recommending the low pass cut off. What is the advantage to flaring the port ends?

[Val]

Yes, all you do is take a typical 12 dB/octave high pass cutoff filter and skew the Q so it has a bump at the tuning frequency of the vented box.

B460 (http://audioheritage.org/vbulletin/showthread.php?t=4557)

What's the cost? A reduction of enclosure real estate by four to six cubic feet and a few more electronic parts in the form of a BX63/BX63A resulting in a shift in alignment from quasi-third order to quasi-fifth order yielding increased group delay which most people couldn't care less about anyway.

I've spent a fair amount of time reviewing the B460 information on this site. Seems like a cool box. The BX63s seem to be a bit hard to come by though. This post has got me asking myself what that extra 4 cu ft buys me? My understanding is that the 2245H, with such a large vas, likes a big box. The way I see it is I need less (or no) eq if I go with the larger volume. Does that make sense?

[4313B]

I've spent a fair amount of time reviewing the B460 information on this site. Seems like a cool box.Or 4645 if the B460 box is too much hassle to clone.
The BX63s seem to be a bit hard to come by though.They are pretty easy to build DIY if someone has the time and a nice hobby box to put the parts in. I built a few in some Niles switch boxes back in the day.
This post has got me asking myself what that extra 4 cu ft buys me?Less floor space that might not be an issue if you have it to burn.
My understanding is that the 2245H, with such a large vas, likes a big box.It likes a seven to fourteen cubic foot box. The larger the box and the lower the tuning the more excursion limited it becomes. Probably not an issue in a home environment but JBL had problems with them in the SR arena (hence the rise of the 2242H).
The way I see it is I need less (or no) eq if I go with the larger volume. Does that make sense?If you have the room to burn. I personally put my foot down at ten cubic feet. :p

[Loren42]

Thank you for running those numbers on bb and recommending the low pass cut off. What is the advantage to flaring the port ends?

Port flares reduce vent noise and chuffing and they also reduce compression, which can lead to some distortion artifacts.

It isn't most critical thing you need to do when designing a cabinet, but if you can flare the port is simply adds a little more overall quality to the system.

Parts Express sells an ABS port kit (you will need two):

http://www.parts-express.com/pe/showdetl.cfm?Partnumber=268-354

I think Madisound does the same.

[Valentin]

there are cad plans for the B460 in this site so you would only need to go to cnc place

here are the ones i did

http://i24.photobucket.com/albums/c7/ValentinR/DSC_0066.jpg

i did two of them in mirror image

[Val]

Thanks for explaining. I will incorporate that into this design.


Port flares reduce vent noise and chuffing and they also reduce compression, which can lead to some distortion artifacts.

[Val]

here are the ones i did

:applaud:Beautiful!

[Loren42]

Thanks for explaining. I will incorporate that into this design.

Vance Dickason's The Loudspeaker Design Cookbook (ISBM 1-882580-33-8) would be a great book to pick up.

[Loren42]

there are cad plans for the B460 in this site so you would only need to go to cnc place

here are the ones i did

http://i24.photobucket.com/albums/c7/ValentinR/DSC_0066.jpg

i did two of them in mirror image

Bravo!

[4313B]

here are the ones i did

i did two of them in mirror imageVery nice! :yes:

[Val]

If you have the room to burn. I personally put my foot down at ten cubic feet.
I do have the floor space to burn and it works out well in this case to have a large platform to put my equipment rack and yet-to-be-purchased TV on.


The larger the box and the lower the tuning the more excursion limited it becomes. Probably not an issue in a home environment but JBL had problems with them in the SR arena (hence the rise of the 2242H).

After reading your comment and re-reading the 1983 Sub-Woofer article, I think I'm going to stick with my 12.8 cu ft cabinet and tune it for 26 Hz. According to the article a box this size does pretty well with no eq.

However, I want to understand your excursion warning. My understanding is that the cone will have the least excursion at resonance, in this case 26 Hz. So I'm guessing that excessive excursion will occur below 26 Hz. Is that right?:hmm: If so, does including a 20hz high pass solve the problem?

I appreciate your help with this.

[4313B]

Probably the easiest thing to do is use WinISD and model your specific application. It should show you excursion characteristics.

Check this link out and see if it helps you. I haven't looked at it in detail. http://www.subwoofer-builder.com/WinISD.htm

[Loren42]

I do have the floor space to burn and it works out well in this case to have a large platform to put my equipment rack and yet-to-be-purchased TV on.



After reading your comment and re-reading the 1983 Sub-Woofer article, I think I'm going to stick with my 12.8 cu ft cabinet and tune it for 26 Hz. According to the article a box this size does pretty well with no eq.

However, I want to understand your excursion warning. My understanding is that the cone will have the least excursion at resonance, in this case 26 Hz. So I'm guessing that excessive excursion will occur below 26 Hz. Is that right?:hmm: If so, does including a 20hz high pass solve the problem?

I appreciate your help with this.

I would not place anything directly on the cabinet if possible. Vibration will be a problem for anything sitting there. Rather, build a shelf over it.

Here are the plots for your 12.8 cubic foot cabinet:

http://www.mdbq.net/2245H_Plots.jpg

Right at 20 Hz the xmax exceeds its limits and the rate of rise of extension is very high from that point downward in frequency.

Here are the box and driver properties:

http://www.mdbq.net/2245H_Data.jpg

[hjames]

Yes, but your work is beautiful ... give them the full link to your build thread!

http://audioheritage.org/vbulletin/showthread.php?t=7877





there are cad plans for the B460 in this site so you would only need to go to cnc place

here are the ones i did

i did two of them in mirror image

[Valentin]

Thanks Hjames

and the sound is very good it is very open i have good integration so some of the times you wonder if their in play until demanded for

i have given them all the power i have just 400w bryston and don't even sweat (more volume that i Need really) i was think of buying the a crown K2 to make them justice but i think i will wait till i finish my listening room

[Val]

Probably the easiest thing to do is use WinISD and model your specific application. It should show you excursion characteristics.

Check this link out and see if it helps you. I haven't looked at it in detail. http://www.subwoofer-builder.com/WinISD.htm

Awesome reference, I see the excursion issue. Thanks for persisting.

I've been using an older version of WinISD and will get the new version.

[Val]

I would not place anything directly on the cabinet if possible. Vibration will be a problem for anything sitting there. Rather, build a shelf over it.

When my LE15A cabinets are cranked they are still to the touch. If I hear you right you are saying that this won't be the case with the 2245H cabinet. I'm planning to use 1" MDF and 2x4 bracing.



Here are the plots for your 12.8 cubic foot cabinet:


Thanks for taking the time to send those across.



Right at 20 Hz the xmax exceeds its limits and the rate of rise of extension is very high from that point downward in frequency.


Yep, see it. That is a steep curve!

[svollmer]

I do have the floor space to burn and it works out well in this case to have a large platform to put my equipment rack and yet-to-be-purchased TV on.



After reading your comment and re-reading the 1983 Sub-Woofer article, I think I'm going to stick with my 12.8 cu ft cabinet and tune it for 26 Hz. According to the article a box this size does pretty well with no eq.

However, I want to understand your excursion warning. My understanding is that the cone will have the least excursion at resonance, in this case 26 Hz. So I'm guessing that excessive excursion will occur below 26 Hz. Is that right?:hmm: If so, does including a 20hz high pass solve the problem?

I appreciate your help with this.


You might not need another opinion on this, but I built two of the 12 cubic foot boxes based on the 1983 article and I couldn't be happier. They truly go infrasonic and with the right recordings (Telarc recordings for example) can move air across the room that feel like waves travelling by you. Because the BX63 wasn't readily available, I use an AudioControl Richter Scale III crossover. http://www.audiocontrol.com/t35/16463/171119/Room-Correction-Processors/The-Richter-Scale-Electronic-Crossover-24dB--Octave-with-Bass-Equalization.html It's a very good crossover, but it is a little dated by now. I bought it because it would allow me to simulate the boost of the BX63A, but I've never had to use any boost.

Make the box as strong and well-braced as you are willing to. "Shelf" bracing that connects all four walls is one good way. You can use the same 1" MDF that your using for the box.

Good luck and show us some pictures!

[Val]

You might not need another opinion on this, but I built two of the 12 cubic foot boxes based on the 1983 article and I couldn't be happier.

I'm glad you commented on this. Always good to have an opinion on a similar design.:)


I use an AudioControl Richter Scale III crossover. http://www.audiocontrol.com/t35/16463/171119/Room-Correction-Processors/The-Richter-Scale-Electronic-Crossover-24dB--Octave-with-Bass-Equalization.html It's a very good crossover, but it is a little dated by now. I bought it because it would allow me to simulate the boost of the BX63A, but I've never had to use any boost.

Interesting that you have not had to use any boost. I am most concerned with protection from subsonic excursion damage which the Richter seems to cover.


Make the box as strong and well-braced as you are willing to. "Shelf" bracing that connects all four walls is one good way. You can use the same 1" MDF that your using for the box.

I've been mulling over the wisdom of my plan to put equipment rack on top of the box. When yours are cranked, how much vibration do you have on the cabinet surface?


Good luck and show us some pictures!

Will do! Do you have any pics of your boxes? Especially any showing how you did the internal bracing?

I appreciate your comments.

[svollmer]

Great! I'm glad my comments were useful.

I never really noticed the panels vibrating too much because the boxes were flush mounted in a wall, underneath an adjacent staircase, and only the front baffles showed when I removed a grill. I made my front baffles 1.5" thick, with the 2245's recessed for a nice look. Also, I braced the heck out of them.

I moved into a new house not too long ago and am finishing off the basement for a new listening room. I'm going to flush mount the boxes into the wall again so only the front baffles show.

I suspect the reason I didn't have to use any boost is because they were located clost to a corner. I'm not sure if that's the reason, but they seriously put out some very mean deep bass. I haven't heard a ton of commercial subs, but of the ones I've heard, NONE of them came close to the 12 FT 2245's.

I'll be happy to take some pictures in a day or two with a driver removed to show you the bracing. Although the cuts in the MDF are nice and straight, I never veneered the outside since they wouldn't be seen. I only painted the fronts black so they'd not be seen from behind a grill. This time, I'm going to go ahead and paint the entire cabinets black because they'll be in a walk-in closet and will be able to be seen when you go in it.

When I get the pictures up, take a look at my ports; they're square but they have the same area as the ports in the 1983 article. This is the second pair of boxes I made for these drivers. The first pair used round ports and I heard no difference between the two. I believe Greg Timbers mentions in the article that the shape makes little difference, but the area and the length must be the same.

[Val]

Great! I'm glad my comments were useful.

I never really noticed the panels vibrating too much because the boxes were flush mounted in a wall, underneath an adjacent staircase, and only the front baffles showed when I removed a grill. I made my front baffles 1.5" thick, with the 2245's recessed for a nice look. Also, I braced the heck out of them.

I moved into a new house not too long ago and am finishing off the basement for a new listening room. I'm going to flush mount the boxes into the wall again so only the front baffles show.

I suspect the reason I didn't have to use any boost is because they were located clost to a corner. I'm not sure if that's the reason, but they seriously put out some very mean deep bass. I haven't heard a ton of commercial subs, but of the ones I've heard, NONE of them came close to the 12 FT 2245's.

I'll be happy to take some pictures in a day or two with a driver removed to show you the bracing. Although the cuts in the MDF are nice and straight, I never veneered the outside since they wouldn't be seen. I only painted the fronts black so they'd not be seen from behind a grill. This time, I'm going to go ahead and paint the entire cabinets black because they'll be in a walk-in closet and will be able to be seen when you go in it.

When I get the pictures up, take a look at my ports; they're square but they have the same area as the ports in the 1983 article. This is the second pair of boxes I made for these drivers. The first pair used round ports and I heard no difference between the two. I believe Greg Timbers mentions in the article that the shape makes little difference, but the area and the length must be the same.

Thanks for your comments. Please don't go to any trouble to take the pictures, I thought you might have some on hand.

[opimax]

naw go ahead and post pictures :) . I am feeling wimpy with just 1 b460 (and no bass traps...yet). Are you in a different house than the 1 I came to?

Seriously pictures are cool

Mark

[svollmer]

No problem. First, here's a drawing of a shelf brace from Vance Dickenson's "Loudspeaker Design Cookbook". I hope there's not copyright infringements! :blink:

[svollmer]

Now, here's one of the subs with the woofer removed.

[svollmer]

Another picture. I used some MDF bracing and some good quality plywood bracing. The plywood you see on the right forms the top of the port. There is about 10" of free space behind the end of the port.

[svollmer]

One more showing the front. The square port is to the right of the driver opening, but it's very hard to see because it's all black and because I'm a lousy photographer. The junk on top of the cabinet is tools and stuff I'm using to finish the basement off.

[svollmer]

naw go ahead and post pictures :) . I am feeling wimpy with just 1 b460 (and no bass traps...yet). Are you in a different house than the 1 I came to?

Seriously pictures are cool

Mark

Yep, I'm in the same house you saw a few years ago and I'M JUST getting around to finishing the basement off. :banghead:

Here's a picture of one bass trap in the room. What you're looking at is a 24" x 24" column, floor to ceiling, of rigid fiberglass with two 24" x 4" thick panels on either side of it; floor to ceiling. There will be columns in the four corners.

[svollmer]

And here's one of the other side. The big hole in the framing and the closet behind it is where there will be 3 or 4 of the B460 clones stacked and covered with a grill. (Sorry, if I've gone off topic.....)

[mech986]

Pic adjusted to show port a little better. Nice work!

[Loren42]

No problem. First, here's a drawing of a shelf brace from Vance Dickenson's "Loudspeaker Design Cookbook". I hope there's not copyright infringements! :blink:

Fair Use law and you cited the source, so you should be okay. :)

[Val]

One more showing the front. The square port is to the right of the driver opening, but it's very hard to see because it's all black and because I'm a lousy photographer. The junk on top of the cabinet is tools and stuff I'm using to finish the basement off.

Thanks for the pics. Very helpful to see the internal bracing.

[Val]

Bought the 1" MDF at Southern Lumber in San Jose. They have a great mill shop. $17 to cut every piece I need for this project. Worth every penny.

[Val]

Gluing up the right side. No fasteners. Just Tightbond II and good clamps (thanks to Matt for the loan of the clamps!!!).

[Val]

This is the first time I have used these red corner clamps. They are awesome as they force a 90 degree angle. I put these on first with just enough pressure to hold position. Then I throw on the bar clamps and tighten all up. As usual, I leave an 1/8" overhang that I will trim off later with a router and cut-off bit.

[Loren42]

More!

Now wait when he gets the cabinet done and then finds out, like some boat and aircraft builders, that he can't get it out of the basement. :D

[Loren42]

My question is, will the glue alone be strong enough?

I would drill and add some wooden pegs or pins bathed with copious amounts of glue at each corner.

[Val]

My question is, will the glue alone be strong enough?

I would drill and add some wooden pegs or pins bathed with copious amounts of glue at each corner.

So, great question. I'll tell this story to answer it. The first day of High School Wood Shop class the teacher had us glue two pieces of wood together and clamp it. No fasteners, no dowels (biscuits didn't exist), no fancy joinery, just a simple lap joint. The next day we all took our glued up wood and, per teachers instruction, put one side in the vise and hit the other side with a rubber mallet to try to break the glue joint. In every case, the wood failed around the joint, never did the glue joint fail. The point being, if you have a good glue up (good glue, proper clamping, clean, even joint) the glue joint will be stronger than the surrounding wood. In the case of a glue joint, the fasteners there are to act as clamps until the glue dries.

I will of course put in corner blocks and hecka bracing.

[4313B]

In the case of a glue joint, the fasteners there are to act as clamps until the glue dries.That is correct.

[Val]

More!

I plan to take an annoying amount of pictures. :bouncy: Please let me know if I am over doing it.

Now wait when he gets the cabinet done and then finds out, like some boat and aircraft builders, that he can't get it out of the basement. :D

Awesome! I did have a slight panic when I read your post. I'm good. It will fit in the house!

[svollmer]

I plan to take an annoying amount of pictures. :bouncy: Please let me know if I am over doing it.



Impossible! I'm a sub-building voyer and I suspect many others are! I've already learned a few cool things from your pictures. Keep 'em coming!!!

[Mr. Widget]

In every case, the wood failed around the joint, never did the glue joint fail.

In the case of a glue joint, the fasteners there are to act as clamps until the glue dries.True, however in the case of MDF, the glue will tenaciously hold to the highly compressed surface of the material and the soft dust below the surface will easily give. With MDF I think some form of mechanical fastener in addition to wood glue is always best.


Widget

[grumpy]

FWIW, I can concur both with the solid wood/glue being sufficient given
adequate clamping and joint preparation... and with MDF popping loose
just under the surface with a plain butt joint.

In this case, once a shear surface is installed (baffle or back), the weakest
issue will be taken care of. Given that it's not being built for tour duty, it
should be fine. Bracing that ties the initial 'box' to the front and back will
help as well.

[Loren42]

So, great question. I'll tell this story to answer it. The first day of High School Wood Shop class the teacher had us glue two pieces of wood together and clamp it. No fasteners, no dowels (biscuits didn't exist), no fancy joinery, just a simple lap joint. The next day we all took our glued up wood and, per teachers instruction, put one side in the vise and hit the other side with a rubber mallet to try to break the glue joint. In every case, the wood failed around the joint, never did the glue joint fail. The point being, if you have a good glue up (good glue, proper clamping, clean, even joint) the glue joint will be stronger than the surrounding wood. In the case of a glue joint, the fasteners there are to act as clamps until the glue dries.

I will of course put in corner blocks and hecka bracing.

Great story and a great lesson. My limited experience with MDF is that glue does not wick into the material as well as hard or soft woods.

Of course I do not have clamps like those (nor any friends like you do). :applaud:

[Val]

Of course I do not have clamps like those (nor any friends like you do). :applaud:
I had a several GREAT woodworking teachers.

I own two clamps of the pipe variety. Those you see are my good friend Matt's. I feel clamp rich having a total of 10 bar clamps!:applaud:Although, when it comes time to glue up the front baffle I will need a few more.

[Val]

True, however in the case of MDF, the glue will tenaciously hold to the highly compressed surface of the material and the soft dust below the surface will easily give. With MDF I think some form of mechanical fastener in addition to wood glue is always best.


Widget

You are probably right. I plan to brace (frame) the heck out of it with 2 x 4's, sacrificing a bit of my 12.8 cu ft.

Unfortunately, but accurately, I am not fond of all the work and tedium involved with fasteners, biscuits, and joinery. Admittedly this is a character flaw.:o:.

[Val]

Given that it's not being built for tour duty, it
should be fine.

God willing, it will not leave my living room until my kids fight over it.

[Loren42]

You are probably right. I plan to brace (frame) the heck out of it with 2 x 4's, sacrificing a bit of my 12.8 cu ft.

Unfortunately, but accurately, I am not fond of all the work and tedium involved with fasteners, biscuits, and joinery. Admittedly this is a character flaw.:o:.

Pneumatic nailers are not very tedious and I used them on my last project (http://web.me.com/mdebeque/Site/Pyramid_Speakers.html), which had a lot of compound angles.

The resulting holes are small and easy to fill, too.

For those not aware of how they work, the nails are coated with a special hot melt glue. The friction from being driven in melts the glue and it hardens after the nail is in. They are very good at having an exceptional hold and they are easy to drive in with an air nailer.

The only downside is pulling them apart or getting one driven into your fingers! :biting:

[Mr. Widget]

Pneumatic nailers are not very tedious and I used them on my last project (http://web.me.com/mdebeque/Site/Pyramid_Speakers.html), which had a lot of compound angles.

The resulting holes are small and easy to fill, too.Unless I am using pre-veneered plywood, I always use narrow crown staples. Amazing holding power and it really speeds up the process. You don't have to wait for the glue to dry before removing clamps... in most cases, you can glue, staple and move on. After it dries overnight, I fill the holes and sand any slight fit up imperfections with a random orbital sander.


Widget

[Val]

Worked on bracing today. Using 4" #10 screws to hold the 2 x 4's in place and Liquid Nails.

[Val]

This is looking thru the back. The back will bolt on to the cleats using 1/4"-20 T-Nuts and bolts. Vertical braces are centered over where the feet will be. I hope the vertical braces will carry and distribute the load.

[Val]

Here is the back.

[Val]

I decided to do two destructive tests:
- MDF to MDF butt joint, no fasteners, Tightbond II
- MDF to 2 x 4, no fasteners, Liquid Nails

I'll let these set up for a few days and then take a mallet to them.

[svollmer]

I know Liquid Nails is pretty strong, but Tightbond II is amazing. One of the guys in my band dropped his vintage Gibson Explorer and broke the neck off. He and a buddy glued it back on with Tightbond (May have been before Tightbond II; not sure). That was in 1984!!! He still uses the guitar regularly and it stays in tune with no problems.

Can you tell me more about the Neutrik connector you're using?

[JBL 4645]

I know Liquid Nails is pretty strong, but Tightbond II is amazing. One of the guys in my band dropped his vintage Gibson Explorer and broke the neck off. He and a buddy glued it back on with Tightbond (May have been before Tightbond II; not sure). That was in 1984!!! He still uses the guitar regularly and it stays in tune with no problems.

Can you tell me more about the Neutrik connector you're using?

Liquid nails along with wood battens lined around the inside the endorser on my diy sub has held secularly for 11 years.
The inside is all screwed tightly to hold the whole thing tight as a drum.

Looking good Val.:applaud:

[BMWCCA]

Can you tell me more about the Neutrik connector you're using?Not to answer for the OP, but the NL4 SpeakOn is a pretty common connector (4-conductor) and Neutrik makes the nicest stuff and it's quite reasonably priced for the quality! http://www.neutrik.com/us/en/audio/203_324141/speakON_Lockable_Loudspeaker_Connector_group.aspx

[hjames]

Not to answer for the OP, but the NL4 SpeakOn is a pretty common connector (4-conductor) and Neutrik makes the nicest stuff and it's quite reasonably priced for the quality! http://www.neutrik.com/us/en/audio/203_324141/speakON_Lockable_Loudspeaker_Connector_group.aspx

So - do you buy direct from Neutrik? I didn't see any of the Neutrik connectors I wanted on the Part Express site, for instance ...

[grumpy]

neutrik

-many- electronics suppliers sell them. e.g., Allied has 1700+ listings for Neutrik ...

[svollmer]

Not to answer for the OP, but the NL4 SpeakOn is a pretty common connector (4-conductor) and Neutrik makes the nicest stuff and it's quite reasonably priced for the quality! http://www.neutrik.com/us/en/audio/203_324141/speakON_Lockable_Loudspeaker_Connector_group.aspx

Thanks Phil! I'll look into them for my subs.

Heather: Looks like Markertek sells them: http://www.markertek.com/search=neutrik+speakon

[stephane RAME]

Hello,
NEUTRIK is the right choice
http://audioheritage.org/vbulletin/showpost.php?p=202218&postcount=41
Stéphane :applaud:

[Loren42]

So - do you buy direct from Neutrik? I didn't see any of the Neutrik connectors I wanted on the Part Express site, for instance ...

I used some Neutrik connectors bought from Parts Express and getting them apart after they are assembled is not easy. I slipped with a screw driver and it went 3/4 through my thumb!

I was so pissed I threw them out (after my fingers started working again) and switched to standard banana plugs.

[BMWCCA]

So - do you buy direct from Neutrik? I didn't see any of the Neutrik connectors I wanted on the Part Express site, for instance ...
I suspect for you folk in NoVa, Chuck Levin's Washington Music would stock the most common connectors since they are the norm for SR systems.


In my experience they're quite easy to assemble/disassemble since they use threaded clutch covers that make the strain relief. The only hard part is getting all eight spade terminals connected on the NL8 'cause it gets a bit tight but that's no big deal. I removed the NL8s from my 4345 clones when I moved the CC networks inside the cabinets and went with twin pairs of banana plugs instead. It just made it easier for me to work with my bi-amp setup, but the Neutriks are beautifully made (in Lichtenstein) and make for an error-free positive-contact connection.

[macaroonie]

Heather these connectors are commonly referred to as 'Speakon ' There is a complete series a la XLR as in Male Female / Line / Chassis etc

[hjames]

Heather these connectors are commonly referred to as 'Speakon ' There is a complete series a la XLR as in Male Female / Line / Chassis etc

Nah - at the Opimax Speaker bash, Phil was saying the
Neutrik twin banana connectors were good to have, and,
with bunches of speakers and cables, I thought, hmmm, maybe I should get some!
Currently all my cables have single banana connectors.

No plans to do the fancy 4 way ways on my monitors ...

[opimax]

Phil,

Weren't you pushing for me to use them? And then write you took yours off when you add CC networks? :blink::blink:

Mark

[BMWCCA]

Weren't you pushing for me to use them? And then write you took yours off when you add CC networks? :blink::blink:Your plan was to take the crossovers out of your cabinets so you'd need four pairs of wires to each cabinet, or one Neutrik NL8. I was putting my CC networks inside my 4345s so all I needed was two-pairs of cables from the bi-amp amps, so I removed the NL8s. :)

[opimax]

Well in that case use have 2 sets already made? and don't know what to do with them?:D:D

Maybe we can work something out :applaud::applaud:

I haven't done any research but my 1st reaction was how can you get 4 pairs of 12 gauge attached to a connector of that size?

Mark

[BMWCCA]

Well in that case use have 2 sets already made? and don't know what to do with them?:D:D

Maybe we can work something out :applaud::applaud:

I haven't done any research but my 1st reaction was how can you get 4 pairs of 12 gauge attached to a connector of that size?What I took out won't be very long. I'll measure. The connector uses small spade terminals. They do fit, but I wouldn't want to be making them up on a regular basis! Looks tedious.

[opimax]

I think all 3 front speakers will have external XO, I like the idea of the center having it that way to keep the weight off the the shelf and the ability to easily test different configurations on the unbuilt center.

Mark

[Val]

Cut the whole in the front baffle for the 2245H. Ports will be in the back. Found these different T-nuts at OSH. They don't tear up the MDF like the barbed ones do. I'll probably put a dab of glue over each brad to make sure they don't vibrate loose.

[Val]

Used 14 bar clamps to glue up the baffle. Had to borrow more! Thanks to Dave!

Love those router cut-off bits!

[Val]

I splurged on 6" flared port kits from Parts Express (thanks for the tip Loren). Somehow reading "six inches" is way different then holding these thing in your hands. These are big:blink:. In the pic below the cabinet is face down and the ports are just placed there so I can figure how I'm going to place them (they will attach to the back). I have not cut them to size yet (they will be much smaller).

I've got the new version of WinISD cranked up (thanks 4313B). I had to input the 2245H parameters myself. My next step is to re-calculate my volume factoring in the ports and all those braces.

My vacation is over today so I expect my work to slow dramatically.

[Loren42]

I splurged on 6" flared port kits from Parts Express (thanks for the tip Loren). Somehow reading "six inches" is way different then holding these thing in your hands. These are big:blink:. In the pic below the cabinet is face down and the ports are just placed there so I can figure how I'm going to place them (they will attach to the back). I have not cut them to size yet (they will be much smaller).

I've got the new version of WinISD cranked up (thanks 4313B). I had to input the 2245H parameters myself. My next step is to re-calculate my volume factoring in the ports and all those braces.

My vacation is over today so I expect my work to slow dramatically.

Extraordinary work!

[allen mueller]

You may want to do some final test to check your tuning. I used the same flared ports and the lengths had to be trimmed some from what the equations gave me. WT3 from parts express works well or you could use a tone generator and a multimeter like shown near the end the end of the 1979 enclosure guide.

http://www.lansingheritage.org/html/jbl/plans/1979-manual.htm

[Val]

...like shown near the end the end of the 1979 enclosure guide.

Thanks for the reminder. I generally use the least-cone-movement-by-feel approach.

[Val]

My next step is to re-calculate my volume factoring in the ports and all those braces.

I've got most of the bracing in or laid out (pics later). I've calculated my new volume deducting bracing, port and 2245H volumes. I'm down to 10.8 cu ft.

With WinISD I'm now calculating two 6" dia. ports of 10.5" for 30 Hz.

I'm trying to figure out how to keep the sub from subsonic self destruction. Using WinISD Filter I get good protection from excessive excursion and still have a -3db point at about 33 Hz with a Linkwitz-Riley filter at 20 Hz. I'm trying to figure out how to execute such a filter. (build line-in passive filter? find an amp with built in HPF...most seem to be around 30hz, some sort of purchased signal processing?).

[4313B]

Maybe you should just build it and listen to it before fretting about whether or not you are going to blow it up.

I've personally never blown up a 2245H. I realize that other people like ear bleeding loud but if that's the case then you should be using a 2242H instead anyway.

[Val]

Maybe you should just build it and listen to it before fretting about whether or not you are going to blow it up.


Thanks for that...good advice.

[Val]

Bracing laid out.

[Chas]

Maybe you should just build it and listen to it before fretting about whether or not you are going to blow it up.

I've personally never blown up a 2245H. I realize that other people like ear bleeding loud but if that's the case then you should be using a 2242H instead anyway.

I agree, you'd have to do some crazy stuff in a domestic situation to create a problem with 2245H's. One exception however, IMHO - if you play a lot of vinyl at loudish levels, a subsonic filter (<20Hz) would be a great idea and at the same time, help keep the bass quality nice and clean.

[svollmer]

I decided to do two destructive tests:
- MDF to MDF butt joint, no fasteners, Tightbond II
- MDF to 2 x 4, no fasteners, Liquid Nails

I'll let these set up for a few days and then take a mallet to them.


Did you have a chance to perform the destructive experiment? I'm curious to learn which method held up better.

Thanks!

[Val]

Did you have a chance to perform the destructive experiment? I'm curious to learn which method held up better.

Thanks!

Not yet. The glue as been setting for weeks now. I've been using the glued up bit for some testing. I'll smash it apart soon and post pics.

[Val]

Between work, work and family I've been having a hard time finding any time to work on my sub. Too boot (no pun intended) our Mac that hosts my pictures crashed and is now in the shop. I'll catch up on pics later.

I've finished the cabinet to the point where I can tune it. It's now tuned to 30 Hz without fiberglass. I'm holding off on the fiberglass until I round the edges with my router (very dusty) and sand it. Then I'll check tuning with the glass before gluing up the flared ports.

I did buy a new-open-box Crown XTi1000 on epay for $365w/free shipping. It came Wednesday and works well. I plan to use HiQnet to set up a steep, protective high pass filter around 20Hz and use it for any eq. I have built an RCA-to-XLR cable as described in the XTi manual (XLR pin 2 to RCA center, XLR pin 1 & 3 tied together to RCA outer). Got sum buzz. Need to rework the cable. Any suggestions in converting unbalanced to balanced?

Also bought a Sony Bravia 46" 120Hz LCD tv. Yeah Costco...$1400. Now looking into recievers that both pass HDMI 1.3 and have pre-amps out (for future n-amping). Kinda like the looks of the Yamaha RX-V665. Sure wish these manufacturers explained more about what comes out of the "sub" connector.

Got a couple of vacation days coming and hoping to dig in again!!!

[Val]

Here's the back view with the bracing finished.

[Val]

Here's the back panel with the flared ports mounted.

[Val]

Perimeter of back is anchored with 1/4-20 black oxide hex flathead bolts into T-Nuts. Center is anchored with lag bolts.

[Val]

Back attached and tuning for 30 Hz.

[Val]

2245H mounted

[Val]

Went to an ice rink in Valencia and bought hockey pucks for $2 each. They drill out easily but, ick! They stink as you drill.:blink:

[Val]

Puck feet.

[Val]

Gluing up the grill that will cover just the driver and anchor using PE plastic grill snaps

[grumpy]

Great project!

where are those ports going to fire? (sorry if you've already said).
how are you going to get the Zamboni in there? ;)

[Val]

Great project!

where are those ports going to fire? (sorry if you've already said).


Back towards the wall. My JBL mains also fire back towards the wall. They have about 8" free space as will this box.


how are you going to get the Zamboni in there? ;)

Excellent! My cab's are "Ice Ready":bouncy:

[tomee]

Wow, that's one huge sub! But I bet that's what it takes to get low distortion down to 30 Hz and less.


Puck feet.

Just a tip - the hockey puck rubber rubs off easily, marking up floors or even carpet. I put stick on felt under the ones I've used.

[rusty jefferson]

I've been watching this project with great interest as a friend of mine is building me 2 cabinets for 2245hs. Excellent construction and attention to detail. It looks really great!! I'm also very impressed with the knowledge of members concerning tuning the cabinet, and standing waves, etc. But you lost me when you added the hockey pucks. All that effort to get great sound will be out the window when that cabinet is vibrating like "Magic Fingers". Now I know I've only been a member of this forum a few months, but I have some experience with controlling vibrations in big subs. I also know these ideas are not popular on this forum, but I can assure you they will improve the sound of that sub 100%. As you can see in the attached photo, my old sub has Mapleshade brass footers draining vibes into a 4" Mapleshade platform, that is also drained buy brass footers. All I can tell you is it works. No vibrating window panes, or picture frames, etc. Just really tight, clean bass. I have no financial interest in this stuff, I'm just adding my little bit of knowlege from personal experience. Your project looks great. Sorry if I offended. Send an e-mail if you want to talk about it.

[Val]

Just a tip - the hockey puck rubber rubs off easily, marking up floors or even carpet. I put stick on felt under the ones I've used.

I appreciate the tip. They will go on our hard wood floor and I do plan to cover them with felt or some such.

[Val]

But you lost me when you added the hockey pucks. All that effort to get great sound will be out the window when that cabinet is vibrating like "Magic Fingers". ...Sorry if I offended.

You have some serious coupling to your floor. Awesome!

No offense taken. My cabinet is very large and the hockey pucks make for a stable footing. This cabinet is VERY heavy and I think it will couple easily to the floor, even with these feet.

[BMWCCA]

my old sub has Mapleshade brass footers draining vibes into a 4" Mapleshade platform, that is also drained buy brass footers. All I can tell you is it works. No vibrating window panes, or picture frames, etc.I'm sure I'm demonstrating my ignorance but how does lack of vibrating room components indicate better transmission of the bass? Or by "drain" do you mean channel-away the frequencies you don't want? My windows rattle when a train goes by a quarter-mile away. It seems to me the LF is being transmitted when that happens. Should I set my foundation on pints or hockey pucks to kill it?

If the point is to transmit cabinet vibrations through contact (not my belief), then why bother with reinforcing the cabinet structure. Why not let it vibrate like a bass drum? It would seem, at least to this layman, that spikes would actually de-couple the cabinet from the floor. The pucks might actually de-couple less depending on the durometer of the rubber, which is pretty stiff on a hockey puck from my experience in using them as pads on my automobile floor jacks. Could be a pointless discussion and I do love maple cutting-boards, in the kitchen, but I'm always curious as to the experimentation of folks on this list. ;)

Is the point of the spikes to limit bass output to only what the cone working in its box volume produces and to take away any contact reinforcement (isolation)? Or is it to increase the LF output by effectively coupling the box to a larger plane using the floor, or the entire house, as a radiator surface? :dont-know

I put my 4345s on casters which I figure is a compromise between setting them directly on the floor versus on moving dollies as per the last owner's installation. Am I shooting myself in the foot? Throwing bass out the window? Or cleaning up the LF by de-coupling it from the house? This article was somewhat helpful in discussing the "point" of spikes. Any credibility to his arguments? http://www.audioholics.com/education/loudspeaker-basics/speaker-spikes-and-cones-2013-what2019s-the-point

[4313B]

The last three sentences in the article sum up the issue.

[Val]

On my previous cabinets I've used rubber feet from PE. I'm using pucks primarily because I think they are proportionally correct for this size of cabinet.

[Titanium Dome]

During my Synthesis® install, JBL supplied thin, rubbery adhesive pads for the bottoms of the SAM1HF and SAM@LF units for installation on hard surfaces or on top of each other. No spikes or rubbery feet. Chris was insistent that the pads go between the SAM1HF and SAM2LF units as stacked.

When it came to putting the stacks on the proscenium, I installed Chris-approved, rubber-backed, ribbed pile carpet runner on the top surface, and we placed the units direct on top of that. No amount of torturing that installation could produce an audible or measurable resonance or vibration.

As for the S1S-EX units, they were placed direct on the floor, one standing and one on its side. The floors down there are concrete covered with short loop carpet, so the 130 lb. beasts effectively crush it flat. Chris felt no foot, spike, or pad was necessary or even desired. I guess they're direct-coupled. ;) Obviously, JBL makes no allowance for feet, cones, or spikes in the cabinet construction, though one could always drill holes to do this. :spchless:

With lighter subs and enclosures, spikes or feet might make more sense. The PS1400 and HTPS400 both sit on factory-installed cones. Without them, these subs scoot themselves about on the floor, sliding on hard floors or nap surfing on carpet. The cones make them a bitch to move, and I guess that's the point.

Those hockey pucks should give good isolation from the floor. That's a formidable cabinet and a stalwart project. Congratulations. :)

[rusty jefferson]

I believe the philosophy of the footers is to isolate the cabinet[s] to prevent them from "sharing" vibrations with the rooms/structures around them. If your subwoofer cabinet is vibrating floors/walls, it is also reabsorbing those same vibrations back through the cabinet, but now out of phase/time. Many subs sitting on the floor sound muddy. If your flooring is a thick conventionally constructed hardwood floor, sitting the sub on those brass footers will indeed help to isolate the cabinet and reduce those unwanted "shared" vibrations. In the photo I supplied, note the ceramic tile. Hard surfaces like concrete/tile don't provide as good a "sink" for the vibrations as wood. They will tend to reflect back vibrational energy even more harshly than wood floors. Hence, the maple platform is, in essence providing the service of a extremely ridged floor. The speaker cabinet is well isolated from the room, and also no longer "sharing" vibes. Cabinet strength and stiffness is still critical. We don't want that cabinet to flop like a drum skin. We want all the speaker energy to produce accurate sound. Mounting on rubber feet might help reduce some vibrational energy to the room, however it will do nothing for and possibly increase the cabinet vibrations that have nowhere to dissipate. Clearly, this technique is most applicable to subwoofers and full range speakers with large drivers. Scanning over the linked article showed a major flaw. They weren't coupling the speaker directly to a solid wood floor [or heavy platform] There was a metal stand on carpeting thrown in the mix. Of course those speaker cabinets were trapping the same vibrational energies described above, hence, worsened sound quality. Apples and oranges. It's not so much about cones or footers but about isolating vibrations. I think. Clearly, I'm not an engineer, but I have seen the light on this matter. I have improved the quality of the bass in my system not just some little audiophile tweek amount, but by a factor of 2 or 3. Leading edge attacks are sharper. Plucked and bowed bass is tighter. And Hammond B-3 is cleaner and more powerful. Try replacing the casters on your studio monitors, and if needed add a platform. If it doesn't sound better, they refund the money. You can't loose. I think Val, or anyone, could improve the sound of his/her system with this technique. I'll be happy to demonstrate mine when the new speakers are installed to members in this area.

[svollmer]

To my recollection, the first available or at least commercially successful spikes were the Tip Toes, but The Mod Squad (before Steve McCormack was famous for his amplifiers). Tip Toes were aluminum cones. The premise of the cones was the one example given in the Audioholic article about preventing the speakers from rocking back and forth in opposite action to the woofers movements.

I noticed an extreme example of this "rocking" when I was young and played music way too loud on my Dad's Bose 901's (DON'T throw anything at me!). He had them hanging from the ceiling on chains as recommended by Bose if you weren't using their stands. When I would crank music on them they would literally swing back and forth one or two inches. Of course, a floor-standing speaker wouldn't do that, but it would do it a little if it was sitting on thick carpet.

I put spikes in my 240Ti's back in the 80's and really liked how sturdy it made them and made it almost impossible to tip over during my way too rowdy parties :blink:. I've spiked all my speakers with the exception of my subs ever since. Like Val, my subs are so big that they don't budge when sitting on the hard floor.

[Val]

Progress is slow. I've sanded with 100 grit, then 150, then 220. I wipe down with a damp cloth to raise the grain and re-sand. Not sure if this makes much difference with MDF but I do get a very smooth final finish.

[Val]

After the final sand I wipe down with a tack rag to pick up all the dust.

[Val]

I'm painting the bottom first and then will put on the feet and flip the cabinet and paint the rest.

I use a very good oil based primer, Kilz. Then hit it with 3 coats of Rustoleum flat black. I sand in between coats very lightly with 220 and pick up the dust with the tack rag. It makes for a very nice finish. When I brush on the coats I alternate directions: coat 1 - north/south, coat 2 - east/west, etc.

It looks gloss here as it is still wet.

[Val]

One coat of Kilz oil based primer and three coats of Rustoleum flat black later...

[Val]

Ran out of my preferred 1" fibre glass and so finished off with home depot glass.

[Val]

putting on my foam tape from Parts Express. Also used around driver. Used plumbers putty to seal ports.

[Val]

Lots of discussion regarding our three cats and 6" ports resulted in this abomination!

[Val]

The grill.

[Val]

I also built a matching equipment rack. Still need to hang the LCD TV on the wall and put the center channel under. Maybe this weekend.

[Val]

Love the Crown XTi 1000 amp. Bridged it's about 1000 watts. DSP is controlled by BandManager application. I've dialed in 48db/octave high pass filter at 20Hz to protect the driver from over excursion at subsonic. Still playing around with the low pass.

Put in a bit of boost similar to the BX63 used with the B640.

Sounds fantastic!

[Val]

And the exciting conclusion of our "do you need to use fasteners when gluing up MDF" discussion.

Answer is as was predicted...YES! True, the glue holds, but the top layer of the MDF just pops off.

I am corrected.

[dkalsi]

Someone can correct me if I am wrong, but anytime I glue MDF, I sand before I glue (i.e. - I take of that top layer). However, I still reinforce all joints with screws (not sure its necessary - but I do it just for my peace of mind). Thats the approach I have taken in my 4345 build.

[grumpy]

I don't know if light sanding would do any harm or provide any benefit,...

But I do know I wouldn't count on an MDF butt joint to provide any structural
benefit for something the size/weight of a large speaker cabinet, without
other cabinet design considerations (screws, internal cleats, dadoed or
rabbeted-in front/rear panels, bracing, biscuits, etc...).

Lock-miter joints work well, but can be a pain to set up and require
somewhat specialized tools/bits... when they come together right though,
it's pretty slick. :)

Almost any joint that increases surface area and inter-engagement of parts
(within reason) will help as long as the glue isn't expected to fill voids.

[hificanada]

Just joined this forum , I had my brother inlaw build my sub encloser for the 2245H , 18 in driver. The plans came from the Audio Magazine back in ealy 1980's if I remember. The box is double layered 3/4 press wood on all sides with braces and the front is one 3/4 pressed board and 1 in pressed hard board, glued together, to make a very solid box. also damped the inside with 2in foam all around. The total wieght is aprox 220pds with the driver mounted.
I have always equalized this sub and the Harmon Kardom 665pm with bass contour on. The amp is set not to loud but only to add the very low frequencies needed for the pipe organ, classial music CD's.
Basically it is set that if there is a bass note, you will hear it, below what the human ear can hear.
Love the speaker and is the foundation of my hi-fi, wihout it, the music is not exciting, you can feel it, you can hear it. I have a few people come over to listen to the European large pipe organ's and they are amazed at the sound of the complete system, there is no bass boom, The driver had to be reconed in 1997.
[In memory of Bart]
This sub works with the JBL,L7's
I have attached a few pictures.

[Eaulive]

Ran out of my preferred 1" fibre glass and so finished off with home depot glass.

BEAU-TI-FUL! :applaud:

[MikeBrewster77]

Welcome to the forum, and very nice job on your project!

Just curious, how does corner placement of the L7's work out for you in your room? Certainly no offense meant, but I should think that would be perhaps the least optimal option for that particular model. :duck:

All the best,
- Mike

[BMWCCA]

Just curious, how does corner placement of the L7's work out for you in your room? Certainly no offense meant, but I should think that would be perhaps the least optimal option for that particular model. :duck:Set up correctly, the L7 woofers fire inward. Toed in as they are, they should work fine though the manual suggests a bit more space between the back and side walls—actually three-feet total side and back. I've found the L7s not to be as position-sensitive as others here have. What do you have to say about how they sound, HiFiCanada?

[hificanada]

Set up correctly, the L7 woofers fire inward. Toed in as they are, they should work fine though the manual suggests a bit more space between the back and side walls—actually three-feet total side and back. I've found the L7s not to be as position-sensitive as others here have. What do you have to say about how they sound, HiFiCanada?

Yes, that was a concern but with the room cosmetics I had to take in account, but I did experiment with setting them a few feet away from the wall ,mostly concerned about the rear bass duct and noticed very little a problem with just a small amount of boom ,boxy sound. But I still wanted to keep them there, I put foam in the bass port which solved the problem. The L7's are the best speakers I have ever owned, sound good right out of the box, very well balanced in all the frequency ranges, it excels in classical music,especially the high's and a little bit week on the low frequency, nothing that the sub can't take care of. I have owned an other two JBL speakers, but can't remember the model, it had the 15 in driver and one passive 15 in white in color and mid range, and the VHF and UHF tweeers.
But speaking of "right out of the box'' I have purchased another brand for channel's 3-4, very bad in almost every frequency range, shrill in the horns, boom box, all those problem's I had to fix adding another layer of 3/4 pressed wood all around the inside of the box, without distroying the ouside cosmetics, working through the speaker holes, then damping with 1in egg crate foam, and then bi-amp the horns with tubes, equalizing the lower frequency, keeping that on a SS amp, much better now but nothing like the L7's.

[hificanada]

I believe the philosophy of the footers is to isolate the cabinet[s] to prevent them from "sharing" vibrations with the rooms/structures around them. If your subwoofer cabinet is vibrating floors/walls, it is also reabsorbing those same vibrations back through the cabinet, but now out of phase/time. Many subs sitting on the floor sound muddy. If your flooring is a thick conventionally constructed hardwood floor, sitting the sub on those brass footers will indeed help to isolate the cabinet and reduce those unwanted "shared" vibrations. In the photo I supplied, note the ceramic tile. Hard surfaces like concrete/tile don't provide as good a "sink" for the vibrations as wood. They will tend to reflect back vibrational energy even more harshly than wood floors. Hence, the maple platform is, in essence providing the service of a extremely ridged floor. The speaker cabinet is well isolated from the room, and also no longer "sharing" vibes. Cabinet strength and stiffness is still critical. We don't want that cabinet to flop like a drum skin. We want all the speaker energy to produce accurate sound. Mounting on rubber feet might help reduce some vibrational energy to the room, however it will do nothing for and possibly increase the cabinet vibrations that have nowhere to dissipate. Clearly, this technique is most applicable to subwoofers and full range speakers with large drivers. Scanning over the linked article showed a major flaw. They weren't coupling the speaker directly to a solid wood floor [or heavy platform] There was a metal stand on carpeting thrown in the mix. Of course those speaker cabinets were trapping the same vibrational energies described above, hence, worsened sound quality. Apples and oranges. It's not so much about cones or footers but about isolating vibrations. I think. Clearly, I'm not an engineer, but I have seen the light on this matter. I have improved the quality of the bass in my system not just some little audiophile tweek amount, but by a factor of 2 or 3. Leading edge attacks are sharper. Plucked and bowed bass is tighter. And Hammond B-3 is cleaner and more powerful. Try replacing the casters on your studio monitors, and if needed add a platform. If it doesn't sound better, they refund the money. You can't loose. I think Val, or anyone, could improve the sound of his/her system with this technique. I'll be happy to demonstrate mine when the new speakers are installed to members in this area.
Sounds like a good idea,I will try that, looks alot like my sub on page 1, I also have the JBL 2245H, and have a lot of problems with the windows rattling, glass going lose in the frames, nic-nacs rattling across the table, door knobs rattling and some what muddy sound, most people say," boy you must have it on loud", but it's not, you will know since you have one , that it does not have to be loud to do that, but the queston I have is that some suggest wiring a capacitor across the terminals of the driver for tighter bass, if so, what size capacitor?

[JBL 4645]

Great project!

where are those ports going to fire? (sorry if you've already said).
how are you going to get the Zamboni in there? ;)

What building here a battleship! You sure you haven’t got enough bracing already.

Its more than a great project I haven’t been back to this thread in months and WOW MEGA WOW HOLY WOW GALACTIC GALAXY WOW! That’s no sub. Its space station!:D

Wow Val I didn’t think I’d get to see this finished. I’m, seriously envious.:)

[JBL 4645]

Lots of discussion regarding our three cats and 6" ports resulted in this abomination!

http://www.audioheritage.org/vbulletin/attachment.php?attachmentid=42075&stc=1&d=1254447382

That isn’t going to stop one your three cats poking around, in fact it looks more harmful with the cat getting its head stuck. I’d cover them over with a perforated grill. The cat will be playing with the wire thinking its snake.

They say if cat can get its head in! It can get its body! My cat has been in and out of my sub when it was kitten. Not now because its head is bigger and he can’t get no more.:D Those ports look a bit wider then 4” and most cats will get though that easily. Plus you have all that fibreglass inside and they may not like it if one of them manages to slip though.

Maybe two pieces of wire attached to each port so its crisscrossing then they’d have no hope of getting in not even a kitten.


Use liquid nails as it says its hard as nails! The three ports on my diy JBL 4645 was glued up with liquid nails and its still tough as ever 12 years after.

I do like the grill! Why didn’t I think of that, 12 years ago?

I’d make sure you have plenty of cloth for replacement. The cats are going to so attracted to this new item in the home for weeks. There goes go the cloth grill! :D

That grill needs a little tiny silver JBL badge on it, Sorted!;)

I like the Crown XTi 1000 been looking it up in shopping some good buys around £519.94 and £499.00 most other places are £600 and higher. Nice bit of DSP software on it.

What SPL db do you run the sub at?
http://www.crownaudio.com/apps_htm/designtools/elect-pwr-req.htm

[1audiohack]

My cats and dog all learned the hard and fast way, the cats stay away and the dog stands close by, I think she likens it to an open car window.;)

[JBL 4645]

My cats and dog all learned the hard and fast way, the cats stay away and the dog stands close by, I think she likens it to an open car window.;)

What you saying? Your dog jumped out the car window?

[Val]

That isn’t going to stop one your three cats poking around...

So far, so good. None of my three cats go anywhere near the ports.



I do like the grill! Why didn’t I think of that, 12 years ago?

Thanks. I actually hate covering up the drivers and like to see of the driver as much as I can. On my Center Channel project I'm going to try out a minimalist grill that I hope will keep curious fingers away and allow the driver to be seen even more.
http://www.audioheritage.org/vbulletin/showthread.php?28737-Center-Channel



That grill needs a little tiny silver JBL badge on it, Sorted!;)


Yes I do! Can't find 'em at a reasonable price.



What SPL db do you run the sub at?
http://www.crownaudio.com/apps_htm/designtools/elect-pwr-req.htm
Dang. Great question. I have no idea! The amp bridges at 1000W and the speaker is rated at 400W. So my challenge is to not ruin the driver. Not a problem with music but with 5.1 Home Theater you have to watch it. I've had the 2245H hit the stops a few times! What is a good SPL for a living room?

[moparfan]

i.e. Audyssey or a sound meter to set the levels?

It is easy to overdrive the sub in home theater if you get carried away with the levels.

[JBL 4645]

Val

I’d prefer if the barograph as display of series LED so I can see just how much is going to loudspeakers. At the moment I’ve set the DCX2496 up diffidently to what it was set at 3 days ago. This is what like about the DCX freedom to experiment, with the AVR you get very little experimental flexibility, everything is ether pre-set crossovers and that sucks in my book.

This is why I don’t prefer AVR that have no way of telling what output you’re shoving into the LCRS speakers and the sub has no barograph LED display as well, so you have no clue what so ever. I don’t care if its cheap AVR with 1KW on each LCRS channel.

What I hear around my friends, who’s using the same AVR as me, only he uses the AVR amps and it sounds too damn bright! I’m surprised he hasn’t got tinnitus at the high tinny level he plays it as sometimes.

I’ve got dynamicEQ filters set on all 6 outputs on the DCX2496 to relax LF/HF and some audio limiting for protection. A few additional high-pass filters added in on LF LCR to reduce some harshness in the middle range, I’m not that hard of hearing, not yet! It sounds loud but at calmer and more relaxing level. Softer levels get boasted when they drop down at threshold level, and are then boasted without even realizing, expect I can hear the soundtrack.

Amp levels are set accordingly on for LF and HF LCR if set too high its going to too damn loud! 85db to 105dbc is loud enough for 2 hours (on and off).

[Val]

i.e. Audyssey or a sound meter to set the levels?


I use Audyssey which is built into my Integra DTR 30.1 receiver. Seems to do the job.

[Val]

This is why I don’t prefer AVR that have no way of telling what output you’re shoving into the LCRS speakers and the sub has no barograph LED display as well, so you have no clue what so ever. I don’t care if its cheap AVR with 1KW on each LCRS channel.


At the moment I am happy to have the AVR based RTA, but I do agree in principal with you, it would be good to have better control and better visibility into what is being setup.