2220a and LE75, What to build?

[mrquant]

Hi All,

Long time listener, first time caller.

I just got some pristine pairs of 2220a and LE75s. I would like to try my hand at speaker building. I am OK at woodworking but I should stay in the world of right angles and avoid anything too complicated. I think I could handle a folded horn or a simple scoop. Electronics are no problem.

I have been looking at various designs here and around the web. My first thought is to try and do something like an L200. Would this be a reasonable starter project with these drivers? I am certainly open to other suggestions. I listen mostly to rock. My current main system is solid state but I do have an old MC240 to play with if it is better suited.

Thanks,
John

[speakerdave]

Welcome!

Those are nice components.

My perusal of the resources here does not suggest that woofer in that box. More like the 001 system in an 8-9 cu ft bass reflex, though you can choose a smaller one if you accept a further sacrifice of bass output, already in short supply with that woofer.

That amp is a perfect match, if it's in good condition.

[grumpy]

I'd have a hard time keeping myself from trying this:

http://www.lansingheritage.org/images/jbl/plans/c34/page2.jpg

[Wagner]

I'd have a hard time keeping myself from trying this:

http://www.lansingheritage.org/images/jbl/plans/c34/page2.jpg

Never had the C34, but that C40 is one fine box; for what it's worth, I loved them

I sold an empty C40 single I had to a local hobbyist (another regret); he seemed extremely well versed and his comment was "you can make these do anything" I think he had like 10 of 'em, all original JBL cabs but loaded up with new stuff

I know you already know it, but theoretically identical as far as the numbers go

[Horn Fanatic]

Hi All,

Long time listener, first time caller.

I just got some pristine pairs of 2220a and LE75s. I would like to try my hand at speaker building. I am OK at woodworking but I should stay in the world of right angles and avoid anything too complicated. I think I could handle a folded horn or a simple scoop. Electronics are no problem.

I have been looking at various designs here and around the web. My first thought is to try and do something like an L200. Would this be a reasonable starter project with these drivers? I am certainly open to other suggestions. I listen mostly to rock. My current main system is solid state but I do have an old MC240 to play with if it is better suited.

Thanks,
John

Greetings mrquant -

I have to go with Grumpy on this one. The C34 and the 2220A were made for each other, as the 130A and 2220A share the same exact Thiele-Small parameters, the only difference being the upgraded surround on the 2220. The C40 is a nice box, but with a smaller bass horn, but the 2220A will work admirably in that model also. The question then would be, how much floor space you have available for a C40 Low-Boy, or the C34 Console cabinet. Personally, if you haven't guessed, I prefer the C34 over the C40. The C34 will load your room better.

Good luck, H.F.

[more10]

Pics on the diaphragms on the LE75?

[mrquant]

Just a photo down the throat of the driver? I am not sure I can get a good shot of that.

[mrquant]

Greetings mrquant -

I have to go with Grumpy on this one. The C34 and the 2220A were made for each other, as the 130A and 2220A share the same exact Thiele-Small parameters, the only difference being the upgraded surround on the 2220. The C40 is a nice box, but with a smaller bass horn, but the 2220A will work admirably in that model also. The question then would be, how much floor space you have available for a C40 Low-Boy, or the C34 Console cabinet. Personally, if you haven't guessed, I prefer the C34 over the C40. The C34 will load your room better.

Good luck, H.F.

I like the C34 idea. It will be a little more of a skill builder for me than a simple box but not too challenging. Perhaps I am not searching correctly but I haven't found any detailed plans yet. I did find a brochure on the site. Is there some trick to finding plans? Perhaps some JBL copywrite thing?

Also,should I just track down (or clone) the crossover from a C34?

[macaroonie]

http://www.lansingheritage.org/images/jbl/plans/c34/page1.jpg

[Horn Fanatic]

Is there some trick to finding plans? Perhaps some JBL copywrite thing?

Also,should I just track down (or clone) the crossover from a C34?

Grumpy provided a link to the plans back on the 11th. As for the crossover network, original N1200's come at a steep price on Ebay. You may find later model N1200's on Ebay at lower costs. The cut out for the old crossover housing and the subsequent model housing is the same, so if you score a nice deal on the older networks down the road you can swap them out and no one would be the wiser. Just be sure you include the two vertical inner cleats on either side of the cut-out to mount them, as they are mounted from the inside versus outer flush mount for the later models. If you're on a budget for now, Parts Express has crossover networks available, but they are generic, and not designed for specific loudspeaker components. With those you will require a variable L-Pad for the high frequency attenuation.

One thing I noticed in your first post, you have the LE175, but made no mention of a horn. Any thoughts on that?

At this late date, I wouldn't worry about JBL copy rights. The company did after all, provide builders plans for many production models.

One more thing. Although the drawing mentions how to mount the grille, it does not illustrate the construction arrangement in detail. The C34 has no grill frame. If you proceed with the build, I, or someone on the forum also familiar with the grille construction can talk you through it. It's quite simple, and clever I might add. The other item missing on the drawing is the horizontal wedged cleat mounted to the baffle, which puts tension on the grille fabric. That can all be explained should you go down that road.

Here is an example; http://megatorrents.org/forum/imagehost/graphic/images/2009/July/24/37E3_4A69225E.jpg

http://www.audioheritage.org/vbulletin/showthread.php?10499-C34-mirror-image-pair-with-energizer-cutout

Good luck, H.F.

[mrquant]

Actually I have LE75s rather than LE175s. I have found less information on the LE 75 than the LE175 on the web. Any suggestions on the horn? It is the horn that has made me interested in this project. I have always been a sealed KLH/Advent sort of guy. This is a palate broadening exercise. In fact once I have this together I would like to experiment with other horns. It is a flashback to my final undergrad project when I was a physics student long ago. I spent a couple of months measuring the properties of brass instruments.

[more10]

Just a photo down the throat of the driver? I am not sure I can get a good shot of that.

No, the diaphragm is in the inside of the driver, you will have to remove the back side. But if the screws are sealed this is a collectors item and should not be opened. Can you send pics on the back side of the driver?

Mårten

[Earl K]

( If you can manage the extra space ), I'm especially partial to this Jensen implementation of the BLH ( back loaded horn ) using a 2220a, along with a horn driver . ( Click the pic, to read a really nice back-story to the displayed project ) .


http://i951.photobucket.com/albums/ad353/billwolfer/audio/P1010389Medium.jpg (http://www.diyaudio.com/forums/multi-way/169755-what-would-you-do-cabinet-1.html)

BTW, Zilch passed away a few years back ( our dear, dear old friend was very instrumental to the success of Wilberforce's project ) .

http://i951.photobucket.com/albums/ad353/billwolfer/Jensen_TB-3c.png

Bigger is ( usually ) better in the land of horns ( & waveguides ) . And this Jensen bass horn is bigger than the JBL "scoop" being bandied about .

This projects HF horn is made by QSC , available fromPARTS EXPRESS ! (http://www.parts-express.com/qsc-pl-000446gp-replacement-waveguide-horn-for-hpr152i-2-bolt--245-625)( ignore the use of the Selenium driver, use your JBL or even better, an Altec 802-8G ) .

( If my project ), I'd prefer to see if I could get an Altec 811b radial to fit the space ( instead of any waveguide ) .

:)

Just a thought !

[Horn Fanatic]

( If you can manage the extra space ), I'm especially partial to this Jensen implementation of the BLH ( back loaded horn ) using a 2220a, along with a horn driver . ( Click the pic, to read a really nice back-story to the displayed project ) .


http://i951.photobucket.com/albums/ad353/billwolfer/audio/P1010389Medium.jpg (http://www.diyaudio.com/forums/multi-way/169755-what-would-you-do-cabinet-1.html)

BTW, Zilch passed away a few years back ( our dear, dear old friend was very instrumental to the success of Wilberforce's project ) .

http://i951.photobucket.com/albums/ad353/billwolfer/Jensen_TB-3c.png

Bigger is ( usually ) better in the land of horns ( & waveguides ) . And this Jensen bass horn is bigger than the JBL "scoop" being bandied about .

This projects HF horn is made by QSC , available fromPARTS EXPRESS ! (http://www.parts-express.com/qsc-pl-000446gp-replacement-waveguide-horn-for-hpr152i-2-bolt--245-625)( ignore the use of the Selenium driver, use your JBL or even better, an Altec 802-8G ) .

( If my project ), I'd prefer to see if I could get an Altec 811b radial to fit the space ( instead of any waveguide ) .

:)

Just a thought !

I built that enclosure earlier this year as a test box and stuffed a Jensen G610 inside. It sounds awesome, and will work quite nicely with the 2220. However, my cabinet is only as wide as the baffle because the wings are redundant when placed in a corner. Much less intrusive that way.

[Horn Fanatic]

Actually I have LE75s rather than LE175s. I have found less information on the LE 75 than the LE175 on the web. Any suggestions on the horn? It is the horn that has made me interested in this project. I have always been a sealed KLH/Advent sort of guy. This is a palate broadening exercise. In fact once I have this together I would like to experiment with other horns. It is a flashback to my final undergrad project when I was a physics student long ago. I spent a couple of months measuring the properties of brass instruments.

Sorry for the typo, I misread your post.

If you don't plan to use the acoustical lens, then the field is wide open as to choices of horns. I would stick with the exponential type, rather then a CD horn. CD horns have built in design problems, as Mark Ureda pointed out in an article he co-wrote on the ALTEC Mantaray horns. Phase coherency and upper frequency attenuation being two of them.

The JBL 2345 would be a good start, or the ALTEC 811 as Earl K suggested. I would prefer the 811 also. If you use the ALTEC you will need to drill a new hole pattern to mount JBL driver. The holes will be 30 degrees apart.

[mrquant]

No, the diaphragm is in the inside of the driver, you will have to remove the back side. But if the screws are sealed this is a collectors item and should not be opened. Can you send pics on the back side of the driver?

Mårten

Here you go. What did you learn from this?

[Horn Fanatic]

Here you go. What did you learn from this?

Only one seal is missing. If the driver works, I don't recommend taking it apart. more10 is right, vintage collectors frown on missing seals.

[more10]

One seal intact. How about the other driver? If they work you can sell them as a collectors item and buy a working pair of LE85 with original diaphgragms and also put some money in the bank. I guess they are a bit unusual so maybe you can get a good price.

LE85 have larger magnet and are therefore "better".

Mårten

[mrquant]

One seal intact. How about the other driver? If they work you can sell them as a collectors item and buy a working pair of LE85 with original diaphgragms and also put some money in the bank. I guess they are a bit unusual so maybe you can get a good price.

LE85 have larger magnet and are therefore "better".

Mårten

Good suggestion. If they are rare they should go to someone who cares about that.

[more10]

Good suggestion. If they are rare they should go to someone who cares about that.

Thanks :-)

Put a swap ad on the marketplace part of the forum. If you bargain hard maybe you can get a pair of horns and lenses as well :-). Swap only for LE85 or 2420 (pro version) with original working diaphragms in good shape.

[mrquant]

Sorry for the typo, I misread your post.

If you don't plan to use the acoustical lens, then the field is wide open as to choices of horns. I would stick with the exponential type, rather then a CD horn. CD horns have built in design problems, as Mark Ureda pointed out in an article he co-wrote on the ALTEC Mantaray horns. Phase coherency and upper frequency attenuation being two of them.

The JBL 2345 would be a good start, or the ALTEC 811 as Earl K suggested. I would prefer the 811 also. If you use the ALTEC you will need to drill a new hole pattern to mount JBL driver. The holes will be 30 degrees apart.

Is there something that should go between the horn and the driver? Like a gasket or silicone?

[4343]

Is there something that should go between the horn and the driver? Like a gasket or silicone?

Usually there is a hard gasket stuck to the face of the drivers. Usually gray. Not hard to make some out of a thin (1/16" or so) card stock or cork sheet. No glue or silicone...