The Electronic Subwoofer

[bigyank 0]

Anyone else have one of these? I picked one up last week on a whim to use with my Allison One's. The change is tonal quality is very subtle for the most part.

I never heard of one previously and was wondering when they came out, etc.

Yank

[JKent 0]

Probably more dramatic with a smaller speaker, such as the Four, Five or Six. Here's a copy of the brochure pages, dated 1979.

Kent

[bigyank 0]

Thanks I have a copy of these but was unsure of when they were from. Anyone have a schematic?

[JKent 0]

Just got one (ESW, not a schematic). Had to open it up to De-Ox-It the toggle switch (I thought the unit didn't work but it was just the switch). I'll post a photo. A lot of ICs and stuff in there I wouldn't touch but there are 2 1,000uF 40V electrolytics and I happen to have a couple of nice Nichicon audio grade 1000/50 in my parts box so I may do a little surgery.

Has anyone else been inside? Tom maybe? I know Tom mentioned using this with AR-303s speakers here

I'm trying it out with my AR-91s.

Found an interesting quote in a Stereophile review of a book by Howard Ferstler; "In Howard's mind, "the Electronic Subwoofer failed in the marketplace, in spite of its abilities, for one basic reason: it was actually too good."
 

-Kent

[DavidDru 0]

do tell once you get a feel for it.

[JKent 0]

OK. Cracked it open to install the 1000uF caps and found some other aluminum electrolytics so I replaced those too. There are also some caps that look like styrene and I didn't touch those.

Nice pcb. All the components are marked with the part # and polarity. Here's what I replaced. I used caps I had on hand. The originals were axial, new ones are radial. Had to use heat shrink tubing on the lead because they cross some pcb traces. Yellow arrows on the photo show the new caps.:

• C1 and C2. 1,000uF/40V replaced with 1,000uF/50V Nichicon Audio
• C5, C8, C16, C19, C31, C37. 10uF/40V. Replaced with 10uF/63V Nichicon.

Squirted the EQ/Tape switch some more. It was pretty spotty.

So the result? VERY subtle with AR-91s. A tad more oomph at the bottom. I suspect it would be more impressive with a smaller speaker, like the Allison: Four or any 8" woofer AS speaker such as the AR-4.

Turnover frequency points are 35.5, 41 and 48Hz. I have it set at 35.5Hz.  According to the AR literature the 91's system frequency response is -3dB at 35Hz so I'm guessing the 35.5Hz turnover is right for these speakers. 35.5Hz is the recommended setting for Allison: One and Allison: Three speakers--those have 10" woofers.

 

[mpfrank 0]

I actually have one of these that I bought used on Ebay. I have used it with Allison 115 speakers - 8"woofer - and I couldn't tell any difference. Could be the speakers, could be the room, could be the electronic subwoofer itself, could be the music, could be my ears. Anyway, I'd be happy to sell it if anyone's interested.

[newandold 0]

The Allison Electronic Subwoofer was a great idea back when these speakers were relatively new.

Today, with the average age of Allisons being at least 40 years young, the LAST thing I would be interested in is using a device that is going to have those old woofers working harder than ever.

The opposite is preferred, IMHO....get a competent powered  subwoofer and let that provide the lower frequencies while giving the old Allisons a break.

Save on both amplifier demand and excessive excursion of 40 year plus woofers.

Just sayin

Bill

 

 

 

[ra.ra 0]

I know nothing about this device, but I spotted one at a flea market in Cambridge this past weekend, and it included a user manual with a mildly interesting handwritten note from Roy Allison to Victor Campos that says, "Victor - This is older than I said. Designed in 19__ (?). Roy".

[JKent 0]

10 hours ago, ra.ra said:

I know nothing about this device, but I spotted one at a flea market in Cambridge this past weekend, and it included a user manual with a mildly interesting handwritten note from Roy Allison to Victor Campos that says, "Victor - This is older than I said. Designed in 19__ (?). Roy".

Cool! Hope you snatched it up!

I recently bought a 2nd one, to use with my AR-3a's

[ra.ra 0]

4 hours ago, JKent said:

Hope you snatched it up!

Nope, I didn't know enough about this to dig very deep, so I just had some casual chat with the guy and kept moving along. I assumed it was some sort of proprietary device for a particular Allison model (which I do not own), so my interest level was minimal. Had I known enough to be aware that this works with a variety of acoustic suspension models and manufacturers, I might have dragged it home with me.

How well do these perform with early AR models? Is the benefit noticeable with smaller (8-inch) woofers, too? 

[JKent 0]

Tom Tyson knows more about these than do I but yes--they do work with other acoustic suspension speakers. There are settings for different Allisons but they can be translated into AR, KLH etc equivalents. Tom uses it with an AR 303 and, I think, AR-3a. I use it with the AR-91 and the effect is virtually unnoticeable but I want to try with my AR-4x. I think the difference with a good 8" should be much more pronounced.

Take a look at the brochure I posted above. It discusses where the ESW can and cannot be used. The 12db boost starts at 35.5, 41 or 48Hz so for speakers that go very low normally (AR 12" woofers) the 35.5 is appropriate. Allison says the 41 point works for the Allison: Four (8"). I'd try that or the 48Hz for the AR-4x or KLH 8" speakers. The effect is subtle--there's not that much going on in the 20-35Hz range. It's NOT like those THUMPA THUMPA woofers you hear in cars at stop lights 

I don't "need" another but the handwritten note by RA was enticing!

[Pete B 0]

The excursion requirements go way up with EQ like this, when pushed of course.

This is expecially bad for small speakers, perhaps just use it at low listening levels.

Just about everything on EQ:

http://www.roger-russell.com/equalizers/equalizers.htm

[newandold 0]

6 hours ago, Pete B said:

"The excursion requirements go way up with EQ like this, when pushed of course.

This is expecially bad for small speakers, perhaps just use it at low listening levels."

 

Exactly!

The Allison ESW was ok back in the day when these speakers were NEW....but now, BAD IDEA. 

Subwoofer is the way to go. Great bass extension alternatively, without stressing these precious and now scarce drivers.

There has been an explosion of small, effective outboard powered (and some passive) subwoofers that are great with small to mid sized loudspeakers. 

Unheard of choices compared to what you could do in the seventies.

 

Bill

[Pete B 0]

My point was that you need enough volume displacement relative to the listening level and 

bass extension of the program material.  This is true with or without the EQ but with it you

will hit the bass VD limit on bass heavy material at a much lower midrange volume level.

An 8" woofer with the typical 1/4" Xmax will bottom far sooner than the AR 11" or a pair of

Allison 10".

IMO the Fpeak of that filter should be moved up to 32 or 42 Hz and probably lowered to 6dB

for use with an 8" woofer.