Altec Horns In a Hartsfield?

[robertg]

For the last month I've been thinking that I want to try to build a pair of Hartsfield speakers. Has anyone ever tried mounting Altec 811B horns horns in the Hartsfield cabinet? I think it would look a lot better, and cost a lot less. Does anyone have the dimensions of the Hartsfield where the lens mounts? I believe there isn't enough room if I build the speakers according to the plan.

I'm debating if I should build an exact replica of the Hartsfield, or modify the plans a bit. After everything is done, it still will be a home built speaker with no resale value, probably worth the price of the components only. However I'm not building them to re-sell.

[Challenger604]

For the last month I've been thinking that I want to try to build a pair of Hartsfield speakers. Has anyone ever tried mounting Altec 811B horns horns in the Hartsfield cabinet? I think it would look a lot better, and cost a lot less. Does anyone have the dimensions of the Hartsfield where the lens mounts? I believe there isn't enough room if I build the speakers according to the plan.

I'm debating if I should build an exact replica of the Hartsfield, or modify the plans a bit. After everything is done, it still will be a home built speaker with no resale value, probably worth the price of the components only. However I'm not building them to re-sell.


Did anyone try to put a beetle engine in a Ferrari?

The Hartsfield are very complicated speakers to build...
Good luck!
C

[grumpy]

Obviously, you can do what you like, but I don't think the response of the 811 and its options for drivers will play low enough to meet the bass horn. A jubilee (klipsch) style cab might help some. I believe someone here has, or was going to do this klipsch/JBL mashup. Mixing an altec top with a hartsfield looking klipsch bottom reminds me of a Hank Azaria movie line, "Ahrg ... you just did all three!"

[Mr. Widget]

For the last month I've been thinking that I want to try to build a pair of Hartsfield speakers. Has anyone ever tried mounting Altec 811B horns horns in the Hartsfield cabinet? I think it would look a lot better, and cost a lot less.You are in good company. I think up a lot of crazy things too. Luckily I usually change my mind or come to my senses before acting. :D

I also like the look of the Altec 811/511 horns. They can sound OK, but the 511 is definitely the better version for most applications.

If you are hell bent going down this path, I'd suggest the 511 HF horn and the Klipsch Jubilee bass horn.


Widget

[Horn Fanatic]

For the last month I've been thinking that I want to try to build a pair of Hartsfield speakers. Has anyone ever tried mounting Altec 811B horns horns in the Hartsfield cabinet? I think it would look a lot better, and cost a lot less. Does anyone have the dimensions of the Hartsfield where the lens mounts? I believe there isn't enough room if I build the speakers according to the plan.

I'm debating if I should build an exact replica of the Hartsfield, or modify the plans a bit. After everything is done, it still will be a home built speaker with no resale value, probably worth the price of the components only. However I'm not building them to re-sell.

The 811B was designed to be crossed over at >> 800 cycles <<. Grumpy eluded to this in his comment. The maximum frequency range a Hartsfield bass horn will produce efficiently is no greater than 400 Hz. On a good day. You'll never fit the 511 in a Hartsfield unless you intend to mount it on top. If you chose the 511, find yourself a pair of 511E. Very rare, but Bill Hanuschak has modified them properly. They go for a kings ransom on Ebay. The 511E was an ALTEC factory mod to accommodate the large format ALTEC drivers. Personally I would use the 311-90 horn and call it a day. Best to stick with a large format driver. It does wonders for the Klipsch horn bass section.

"I think it would look a lot better" So, you design by appearance?

I agree with Mr. Widget. The Jubilee bass horn would be the ticket. I would use the 311-90 with the phenolic diaphragm 390 ( I think ) driver, and top it all off with the 2404 tweeter.

H.F.

BTW - The Hartsfield drawing package that can be found in the Heritage library has a few dimensional flaws. I am convinced that drawing package was stolen from the Lansing drafting department before the base line release. There are only one or to revs regarding a piece of hardware, an nothing else. Very suspicious for such a complicated enclosure. If someone had actually taken time to check the drawing package they would have caught the dimensional flaws. Surly someone in the wood shop would have. After building a pair I came to the conclusion that particular model wasn't worth the effort.

[robertg]

So if I go ahead with this project I might as well stick with original JBL. I'm trying to figure out which components will work, the part numbering is a little confusing.

This is what I think I should look for, please correct me if I'm wrong.

Drivers, 375, 376, 2440, 2441

Horn or throat, 2309

Lens 2310

Woofer D-150-4C is probably really expensive, alternatives E145, 2220A, 130A

[Horn Fanatic]

So if I go ahead with this project I might as well stick with original JBL. I'm trying to figure out which components will work, the part numbering is a little confusing.

This is what I think I should look for, please correct me if I'm wrong.

Drivers, 375, 376, 2440, 2441

Horn or throat, 2309

Lens 2310

Woofer D-150-4C is probably really expensive, alternatives E145, 2220A, 130A

You can find the 150-4C on Ebay, but I wouldn't trust any of them. Too many re-cones, and way too may counterfeits. I know many on the forum think the E145 will serve as a replacement for the 150, but it is not my choice for a horn loader. The 130A is a far better horn loader, but being that any you find on Ebay are quite old I wouldn't subject such a relic to driving a compression type horn. Hands down, the 2220 series drivers are the better choice. The 130A & 2220A share identical Thiele-Small parameters, the only difference will be the upgraded surround on the 2220.

A word of note, I have searched high and low for a 15" cone driver suitable for horn loading, and there aren't any in current production. There are a lot of folks out there who think that just because a speaker has a cone, it can drive a horn. Sadly, they are wrong.

If you come across a drawing package for the original Top Loader Hartsfield, the mud magnet model drivers will not fit in the chamber. Only the old D series ( ALNICO magnet ) will fit. The mud magnet models will fit in the Coffin back model.

As for your high frequency; a JBL compliment will cost you a fortune, probably to the tune of $4K -$5K. A pair of 311-90 and ALTEC drivers can be had at the fraction of the cost. If that be the case, Great Plains Audio is the place to go for brand new drivers under warranty. You'll find the 311-90 on Ebay, just be patient. Those auctions don't come up often.


FYI - A large radial horn will provide much better imaging.

[gdmoore28]

A word of note, I have searched high and low for a 15" cone driver suitable for horn loading, and there aren't any in current production. There are a lot of folks out there who think that just because a speaker has a cone, it can drive a horn. Sadly, they are wrong.



Just curious about this assertion. Several of the major manufacturers specifically describe their drivers as suitable for horn loaded cabs. What are you looking for in driver specifications that make them appropriate for horn loading? I know nothing about the subject, so looking for your opinions.

GeeDeeEmm

[Horn Fanatic]

Just curious about this assertion. Several of the major manufacturers specifically describe their drivers as suitable for horn loaded cabs. What are you looking for in driver specifications that make them appropriate for horn loading? I know nothing about the subject, so looking for your opinions.

GeeDeeEmm

.

[robertg]

Would 2215B driver work? I bought a pair of 4502 studio monitors yesterday, and that's what they came with.

[ivica]

.......

H.F.

BTW - The Hartsfield drawing package that can be found in the Heritage library has a few dimensional flaws. I am convinced that drawing package was stolen from the Lansing drafting department before the base line release. There are only one or to revs regarding a piece of hardware, an nothing else. Very suspicious for such a complicated enclosure. If someone had actually taken time to check the drawing package they would have caught the dimensional flaws. Surly someone in the wood shop would have. After building a pair I came to the conclusion that particular model wasn't worth the effort.

Uuuuhhhhh
I can not imagine to realize such

ivica

[ivica]

..

A word of note, I have searched high and low for a 15" cone driver suitable for horn loading, and there aren't any in current production. There are a lot of folks out there who think that just because a speaker has a cone, it can drive a horn. Sadly, they are wrong.

If you come across a drawing package for the original Top Loader Hartsfield, the mud magnet model drivers will not fit in the chamber. Only the old D series ( ALNICO magnet ) will fit. The mud magnet models will fit in the Coffin back model.

.....

Hi Horn Fanatic,

what about new 2216Nd for such horn loading???

Regards
ivica

[grumpy]

I'm going to sound "grumpy", but did you first refer to HF's criteria before asking this? Posted a number of times...

[Challenger604]

Uuuuhhhhh
I can not imagine to realize such

ivica


You have to be an expert to make a Hartfield! You really have to know what you are doing!
That's what I was saying below...

[Horn Fanatic]

Hi Horn Fanatic,

what about new 2216Nd for such horn loading???

Regards
ivica

With an EBP of 89.2 the 2216Nd would not be my choice as a horn loader.

[Horn Fanatic]

Would 2215B driver work? I bought a pair of 4502 studio monitors yesterday, and that's what they came with.

The 2215 is the commercial version of the LE15, and would be a very poor choice as a horn loader. One my pet peeves about JBL is when the company opted to load the Paragon with the LE 15. IMO, it was a colossal bonehead move, since the 130A was used in the C31, C34, and C43 ( C435 ), and as an option in the C55 ( C550 ). I'm just glad the Hartsfield didn't suffer the same fate before it was taken out of production. I'm not sure it would have even fit in the Top Loader Hartsfield. The build up of plywood on the inside of the service panel allowed just enough room for the magnet cover of the 150-4C. The volume of that chamber couldn't have been more than a cubic foot, probably less. I know the company loaded the 4500 series theater horns with the 2205, but that model makes for a mediocre horn loader also. I have also seen many images on the internet of 4520's loaded with LE 15's. I can safely state that box loaded with the LE 15 produces a week bass.

Also, the fs of the 2215 is far too low a frequency for horn loading. The horn fc would be approximately 18 Hz, and to design an exponential or hyperbolic horn around that frequency for domestic use would result in what is called a discontinuity. Meaning, the horn wouldn't have a chance to have a useful expansion which would make it behave more like a short horn loaded port. In order for a horn with an fc of 18 Hz to expand to something useful would require an inordinate degree of floor space, not to mention an inordinate amount of lumber to build it. Not only that, but the chamber volume required for the 2215 in addition to constructing a large horn in front or back of it would preclude any notion of construction of a reasonably sized horn for domestic use.

"I bought a pair of 4502 studio monitors yesterday, and that's what they came with"

And that is where the 2215 shines. In a vented enclosure.

[Horn Fanatic]

Uuuuhhhhh
I can not imagine to realize such

ivica

That lay out is from a Japanese site where all the dimensions were converted to metric, including the wrong ones I sighted.

[Horn Fanatic]

You have to be an expert to make a Hartfield! You really have to know what you are doing!
That's what I was saying below...

It may have been Don McRitchie who wrote that the internal geometry change from the Top Loader Hartsfield to the Coffin Back model came about because of the labor intensive hassle it was to service the 150-4C. If anyone has taken one apart they'll know what I mean. Imo, the Top Loader model is much easier to cut and assemble, which is comprised of considerably fewer parts and cuts. I wonder if that was the real reason, as it would have made sense to just turn the Hartsfield bass section upside down, making the driver service panel more accessible. Doing so wouldn't have made a difference acoustically.

However, in an article about the Jubliee, Paul Klipsch himself praised the new design over the former because the Jubilee followed a single axis folding geometry, versus the contorted geometry of the KlipscHorn. It may be possible that the Coffin Back bass section as a single axis folding geometry offers a higher frequency range than the contorted Top Loader configuration.

[ivica]

With an EBP of 89.2 the 2216Nd would not be my choice as a horn loader.

Hi Horn Fan..,

Thank You.
so from
http://speakerplans.com/index.php?id=faq6

"I did say that a driver that would be good for use in a horn usually has an EBP (efficiency bandwidth product) of greater than 130. This is not the rule though, it is only a guide. EBP is Fs divided by Qes and gives a rough approximation of how well the motor system can control the cone. It doesn't always follow that high EBP figures automatically make the driver suitable for horn loading, there are so many parameters that dictate which driver to chose for a particular horn and so many different horns for different jobs."

But with Radian 2216 (EBP=38.7/0.43) almost like JBL 2214nd EBP......something interesting
http://inlowsound.weebly.com/spiral-bass-horn.html



Regards
ivica

[Horn Fanatic]

Hi Horn Fan..,

Thank You.
so from
http://speakerplans.com/index.php?id=faq6

"I did say that a driver that would be good for use in a horn usually has an EBP (efficiency bandwidth product) of greater than 130. This is not the rule though, it is only a guide. EBP is Fs divided by Qes and gives a rough approximation of how well the motor system can control the cone. It doesn't always follow that high EBP figures automatically make the driver suitable for horn loading, there are so many parameters that dictate which driver to chose for a particular horn and so many different horns for different jobs."

But with Radian 2216 (EBP=38.7/0.43) almost like JBL 2214nd EBP......something interesting
http://inlowsound.weebly.com/spiral-bass-horn.html



Regards
ivica



Hi ivica -

I have written on other threads regarding the topic of EBP, as it is the first figure I consider, but not the only. An EBP of 130 may be acceptable to some, but not me. Again, the lower the number, the larger the chamber must be. Stuffing a driver with a low EBP into a small chamber will result in not so articulate bass. Sure, the L-F may be there, but what does it sound like?

A driver with a high EBP will produce the low end with a higher degree of 'snap', tightness, articulation. This is the point I make aboput the difference between the 150-4C and LE 15 in the Paragon. I knew within 3 seconds on a test CD the 150 is a far superior horn driver than the LE 15. As a test, I loaded an ALTEC 416-8B into a 4530 horn cabinet, and the result was awful.

The EBP for the 416-8B is 76. The EBP for the 2220 A is 194.73. The hearing is in the believing why a driver with a low EBP such as the 2215 & 416-8B are not suitable for horn loading.

H.F.

[ivica]

Hi ivica -

I have written on other threads regarding the topic of EBP, as it is the first figure I consider, but not the only. An EBP of 130 may be acceptable to some, but not me. Again, the lower the number, the larger the chamber must be. Stuffing a driver with a low EBP into a small chamber will result in not so articulate bass. Sure, the L-F may be there, but what does it sound like?

A driver with a high EBP will produce the low end with a higher degree of 'snap', tightness, articulation. This is the point I make aboput the difference between the 150-4C and LE 15 in the Paragon. I knew within 3 seconds on a test CD the 150 is a far superior horn driver than the LE 15. As a test, I loaded an ALTEC 416-8B into a 4530 horn cabinet, and the result was awful.

The EBP for the 416-8B is 76. The EBP for the 2220 A is 194.73. The hearing is in the believing why a driver with a low EBP such as the 2215 & 416-8B are not suitable for horn loading.

H.F.
Hi Horn Fanatic,
Many thank for Your more elaboration about bass horn application.
I have no experience in that area.
One question :have You ever seen something technical explanation about port position on the baffle relative to the driver placemen,and the box size and its dimensions.?

Regards
Ivica

[robertg]

The 2215 is the commercial version of the LE15, and would be a very poor choice as a horn loader. One my pet peeves about JBL is when the company opted to load the Paragon with the LE 15. IMO, it was a colossal bonehead move, since the 130A was used in the C31, C34, and C43 ( C435 ), and as an option in the C55 ( C550 ). I'm just glad the Hartsfield didn't suffer the same fate before it was taken out of production. I'm not sure it would have even fit in the Top Loader Hartsfield. The build up of plywood on the inside of the service panel allowed just enough room for the magnet cover of the 150-4C. The volume of that chamber couldn't have been more than a cubic foot, probably less. I know the company loaded the 4500 series theater horns with the 2205, but that model makes for a mediocre horn loader also. I have also seen many images on the internet of 4520's loaded with LE 15's. I can safely state that box loaded with the LE 15 produces a week bass.

Also, the fs of the 2215 is far too low a frequency for horn loading. The horn fc would be approximately 18 Hz, and to design an exponential or hyperbolic horn around that frequency for domestic use would result in what is called a discontinuity. Meaning, the horn wouldn't have a chance to have a useful expansion which would make it behave more like a short horn loaded port. In order for a horn with an fc of 18 Hz to expand to something useful would require an inordinate degree of floor space, not to mention an inordinate amount of lumber to build it. Not only that, but the chamber volume required for the 2215 in addition to constructing a large horn in front or back of it would preclude any notion of construction of a reasonably sized horn for domestic use.

"I bought a pair of 4502 studio monitors yesterday, and that's what they came with"

And that is where the 2215 shines. In a vented enclosure.
After I posted that question I did some reading and came to the same conclusion. I ended up getting a pair of 130A woofers and I found a pair of 2390 horns. I think I'm going to get a 2441 driver for the horns. From what I've read, they go higher than the 2440, so I won't need a tweeter. Correct me if I am wrong.

[Earl K]

Glad to see you haven't been put off from your horn-loaded endeavour .

Here's a nice thread ( over at DIY ) for a bit of inspiration . ( Click the pic )

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

It's well worth the read time to understand the story behind this particular pair of BLH (back-loaded-horn ) Jensen copies.

One of the beauties of the pictured system is that because the front baffle ( holding the woofer & horn ) must be removable it allows a person to try different horns in place ( to find what works best for their situation ) .

I happen to like Radials ( particularly the throat-less variety / first championed by W.E. post WWII) .

71947 (http://www.hifilit.com/Western%20Electric/page%2075.jpg)

I listen to an Altec 288-8K through an Emilar EH-500-2 Radial Horn ( using a 1.4"-2" adapter ) .

BTW, Brazilian clones of the QSC horn ( seen in the first pic ) are being blown out by P.E. for a measly $10.00 USD .

Canadians will want to purchase them through P.E.'s eBay store front ( it's the cheapest shipping into Canada since it goes through the Global Shipping System ) . ( Click the pic for the link )

71943 (http://www.ebay.com/itm/PRV-Audio-WG35-25-B-1-90-x-60-ABS-Waveguide-2-3-Bolt-/221645016239)

Forget the original ad-copy for this horn, it's a planar ( mostly conical ) wave-guide ( with no exponential curves ).
- The biggest knock against it ( being planar/conical ) is though it's big, it barely affords a 1K crossover point ( not really a problem when using 130's / 2220's ).


Here's an expensive ( almost throat-less / QUICK-ENTRY ) Radial close in size to the 811b that you mentioned ( & a lot more affordable ).

I consider this a great project-horn opportunity.
Click the pic! ( again this seller uses the Global Shipping System available to US sellers that saves You & I money/ plus allows one to figure out actual "Landed Costs" since this includes taxes, duties & brokerage ).

http://i.ebayimg.com/images/g/7rEAAOSwNSxU27uC/s-l500.jpg (http://www.ebay.com/itm/10-x-18-ABS-Plastic-1-3-8-Screw-On-Bi-Radial-Horn-For-Speaker-Cabinet-/331477247778?pt=LH_DefaultDomain_0&hash=item4d2d956722)
:)

[Horn Fanatic]

After I posted that question I did some reading and came to the same conclusion. I ended up getting a pair of 130A woofers and I found a pair of 2390 horns. I think I'm going to get a 2441 driver for the horns. From what I've read, they go higher than the 2440, so I won't need a tweeter. Correct me if I am wrong.

Very good choice and find on the 130A. The 2440 was the commercial number assigned to the 375 driver. The 375 began to tank around 7.5KHz, whereas the 2441 began to tank around 10KHz. Keep in mind when 375 driver was developed, the dynamic range of movie sound tracks back in the day wasn't that great.

As for using a tweeter, only you can make that call. The 2440 isn't capable of producing the 'sizzle' of a tweeter.

H.F.

[Horn Fanatic]

Glad to see you haven't been put off from your horn-loaded endeavour .

Here's a nice thread ( over at DIY ) for a bit of inspiration . ( Click the pic )

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

It's well worth the read time to understand the story behind this particular pair of BLH (back-loaded-horn ) Jensen copies.

One of the beauties of the pictured system is that because the front baffle ( holding the woofer & horn ) must be removable it allows a person to try different horns in place ( to find what works best for their situation ) .

I happen to like Radials ( particularly the throat-less variety / first championed by W.E. post WWII) .

71947 (http://www.hifilit.com/Western%20Electric/page%2075.jpg)

I listen to an Altec 288-8K through an Emilar EH-500-2 Radial Horn ( using a 1.4"-2" adapter ) .

BTW, Brazilian clones of the QSC horn ( seen in the first pic ) are being blown out by P.E. for a measly $10.00 USD .

Canadians will want to purchase them through P.E.'s eBay store front ( it's the cheapest shipping into Canada since it goes through the Global Shipping System ) . ( Click the pic for the link )

71943 (http://www.ebay.com/itm/PRV-Audio-WG35-25-B-1-90-x-60-ABS-Waveguide-2-3-Bolt-/221645016239)

Forget the original ad-copy for this horn, it's a planar ( mostly conical ) wave-guide ( with no exponential curves ).
- The biggest knock against it ( being planar/conical ) is though it's big, it barely affords a 1K crossover point ( not really a problem when using 130's / 2220's ).


Here's an expensive ( almost throat-less / QUICK-ENTRY ) Radial close in size to the 811b that you mentioned ( & a lot more affordable ).

I consider this a great project-horn opportunity.
Click the pic! ( again this seller uses the Global Shipping System available to US sellers that saves You & I money/ plus allows one to figure out actual "Landed Costs" since this includes taxes, duties & brokerage ).

http://i.ebayimg.com/images/g/7rEAAOSwNSxU27uC/s-l500.jpg (http://www.ebay.com/itm/10-x-18-ABS-Plastic-1-3-8-Screw-On-Bi-Radial-Horn-For-Speaker-Cabinet-/331477247778?pt=LH_DefaultDomain_0&hash=item4d2d956722)
:)

I built a pair of the Jensen folded horn enclosures, and much to my expectation the design delivers very articulate bass. I loaded them with the G610 Triax.

[Horn Fanatic]

Glad to see you haven't been put off from your horn-loaded endeavour .

Here's a nice thread ( over at DIY ) for a bit of inspiration . ( Click the pic )

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

It's well worth the read time to understand the story behind this particular pair of BLH (back-loaded-horn ) Jensen copies.

One of the beauties of the pictured system is that because the front baffle ( holding the woofer & horn ) must be removable it allows a person to try different horns in place ( to find what works best for their situation ) .

I happen to like Radials ( particularly the throat-less variety / first championed by W.E. post WWII) .

71947 (http://www.hifilit.com/Western%20Electric/page%2075.jpg)

I listen to an Altec 288-8K through an Emilar EH-500-2 Radial Horn ( using a 1.4"-2" adapter ) .

BTW, Brazilian clones of the QSC horn ( seen in the first pic ) are being blown out by P.E. for a measly $10.00 USD .

Canadians will want to purchase them through P.E.'s eBay store front ( it's the cheapest shipping into Canada since it goes through the Global Shipping System ) . ( Click the pic for the link )

71943 (http://www.ebay.com/itm/PRV-Audio-WG35-25-B-1-90-x-60-ABS-Waveguide-2-3-Bolt-/221645016239)

Forget the original ad-copy for this horn, it's a planar ( mostly conical ) wave-guide ( with no exponential curves ).
- The biggest knock against it ( being planar/conical ) is though it's big, it barely affords a 1K crossover point ( not really a problem when using 130's / 2220's ).


Here's an expensive ( almost throat-less / QUICK-ENTRY ) Radial close in size to the 811b that you mentioned ( & a lot more affordable ).

I consider this a great project-horn opportunity.
Click the pic! ( again this seller uses the Global Shipping System available to US sellers that saves You & I money/ plus allows one to figure out actual "Landed Costs" since this includes taxes, duties & brokerage ).

http://i.ebayimg.com/images/g/7rEAAOSwNSxU27uC/s-l500.jpg (http://www.ebay.com/itm/10-x-18-ABS-Plastic-1-3-8-Screw-On-Bi-Radial-Horn-For-Speaker-Cabinet-/331477247778?pt=LH_DefaultDomain_0&hash=item4d2d956722)
:)

I built a test pair of the Jensen folded horn enclosures, and much to my expectation the design delivers very articulate bass. I loaded them with the G610 Triax. I hope in the near future to load them with the 2220 driver.

The only mod I did was to build the boxes without the 'wings', as they are redundant. The box is less intrusive without them.

H.F.

BTW - As I have seen no evidence that Jensen put that design into production, the only commercial application I know of is a system Electro-voice produced which was taller to accommodate a high frequency section. That cabinet was only 24 inches wide, as mine are. I have also seen a drawing for a University version of the Jensen horn that was also extended to accommodate a large radial horn.

As you know since you found the magazine article drawing for the Jensen, there was also a shorter version to house a 12 inch CoAx.

[vinny]

What about the 15b with foam surround?