2245H Sub-Woofer Project

[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!

[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.

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.

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!

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!

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. 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!

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/d...ct-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?