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A acoustic suspension article from Audioholics


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Our resident experts here at CSP concluded quite some time ago that there are pretty much no available new woofers that are suitable for use in acoustic suspension speakers (including those being marketed as AR replacements). But it's good to see it being said outside of our little corner of the world.

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  • 3 weeks later...

I'm fairly certain that is Steve F on here so not really an outside source.  If you read Steve Feinstein's

bio, you'll see mention of working at BA and Atlantic Technologies, just as Steve F has mentioned here.

And I've found a 12" that performs very similarly to the AR woofer in the same enclosure volume.

I'll try to demo it at the next Frankenfest.

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It does not have the truncated sides so I don't think it will fit in any of the AR-11 type boxes,

but it does fit in a Large Advent utility cabinet that is about the same volume.  Might fit in an

AR-9 type box but I don't recall if there is any sort of restriction on the diameter.

It provides the correct Fc in the same box volume, is 4 ohms, and I'd call it an acoustic suspension woofer.

I've used it with a miniDSP crossover and have not determined if component

changes are required.  It is also a 4 ohm woofer.

I'd estimate that it provides at least 3 dB more MaxSPL output due to higher Xmax

and a bumped back plate.

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Yes directly wired and 12 dB/oct in the miniDSP with baffle step.

I've also tried 24dB/oct but this is another application, not trying to be similar to the AR s - yet.

If I get around to an AR like design I'll try to do it passive.

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I play the electric, acoustic and resonator guitar; all have a completely different sound and all probably would benefit from an Amplifier (amp/amps) and speaker designed just for each one and sometimes you can get them. There are 2 types of amps used and 2 types of speaker enclosures. Solid State and tube are the amps and open speaker cabinets (cabs) and mostly sealed cabs.

The open cabs are usually combination (or combo) amps that house the amplifier AND the driver and the other has a separate enclosures for the amp and the drivers. I say they are mostly closed because the cabs are connected to the amp with a 2 conductor 1/4" jack; sometimes shielded cable is used; so there is at least one if not two 1/4" holes in the back of the cab. Sometimes the driver is installed from the front of the housing and sometimes from the back. Many times you'll see a Celestion used in the famous 4 X 12" 1961A and B cabs Marshall makes. Marshall uses the same model speakers in combo (open cab) amps and the other mostly sealed cabs. The same speaker sounds way different in each application. I'm a big fan of the mostly closed cabs, I can't see how one or two 1/4" holes in the back of a cab can be called a vent but by definition they are vents, the combo cabs remind me of my Father's Sylvania Mono Hi Fi from the late 50's with radio and turn table, it had one 12" and one 4" driver with a simple crossover. It had a Masonite cover on the back that was vented for the tube heat generated inside, it had horizontal openings for air to get in and out and I'm sure some of the sound but I'm also sure that wasn't on the minds of the engineers at the time.

I know guitar amp drivers aren't made anything like a fine audio driver, the guitar driver has a lot less to do. I have never heard the amount of differences in stereo amp/driver quality that I have with guitar equipment. I belong to the tube amp side of the discussion, they provide a warmer sound, have a more natural distortion although solid state amps have a lot to offer and are getting better every year. Many solid state amps try to sound like tube amps, no tube amp manufacturer (MFR) will ever try to emulate a solid state sound.

So what would make a great guitar driver? What would make a great enclosure? Those are questions that will have subjective answers of course. But as we all know facts are inconvenient things. Certainly we can apply Hi Fi speaker technology to this question.

In guitar amps high wattage doesn't mean a lot louder, the decibel difference in say a 20 or 30 watt amp and a 100 watt amp is about 7 decibels. If you drive  the 20 watt amp (turn it up) it's going to distort a lot easier/earlier than the 100 watt amp, the big difference is "head room" or the ability to go loud without distortion.

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  • 1 month later...

Dayton 12" 4 ohm woofer in 1.6 cu ft having as low or better Fc and Qtc as the AR 12" woofer:

Old Advent OLA Utility boxes are cut for a 12" so they drop right in for evaluation purposes.

The nicer real wood veneered boxes will not take a normal 12" because the trim reduces the 

width too much.  The NLA woofer opening is smaller so it also will not fit without cutting.



A pair of them playing as 3-ways at Frankenfest this past weekend:


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I did a passive crossover at about 250 Hz, using junk box parts but it would have

been even easier to biamped it with a MiniDSP.  I did 1st order to the top end and 2nd

order with a bit of damping in the cap shunt.

I came up with this configuration about 20 years ago, others use it also.

The top end is Celestion SL6, these are the first version in the series with the copper

dome tweeter that provides a depressed top end that some like.   Thread on AK:


I bought them knowing that one tweeter was blown.  The copper tweeter has a high Q

resonance in the top end that must be notched so the crossovers are tuned to match the

tweeters.  Also the output at the very top end is matched to the design spec by another factory

tuning.  The next revision of the system, the SL6S, and following 6Si and SL700, all used a newer

aluminum tweeter that pushed the resonance above 20K, but JA's measurements in 

Stereophile showed a large notch at 15K that is not acceptable IMO.  All systems with the 

aluminum tweeter do not have any factory tuning of the crossover.  There was only one version

of the 1.25" copper tweeter and one of the 1.25" aluminum tweeter used in these systems as 

far as I know, and no other tweeters.

I decided to adapt the Dayton RST28F large 1 1/8" tweeter which I had on hand, to it as a reasonable

replacement.  There is also an aluminum dome Dayton version that shouldn't be difficult to fit.

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I think it sounds great, we ran them with 200W/ch and I think they could have used 

more power.  One young guy at the show put it that they kicked ass and had a big

smile while he listened to them.  He also said that he just heard music and it didn't 

sound like it was coming out of speakers which I take as a significant compliment.

That is how many described the SL6 s when they came out.  He does a lot of restorations

on vintage gear and has owned some big impressive speakers.

I plan to build a full 3-way in the box and once that's done I'll compare them to the AR-11.

I could obviously use the plate that I 3D printed with the mid and tweeter but I might

want to try other drivers.

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