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setaG_lliB
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Playing with a 41 year old subwoofer

Fri Sep 15, 2017 12:37 pm

Me again with one of my quarterly vintage audio posts. :)

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I snagged this big guy a few months ago. This is a 41 year old Dahlquist subwoofer! Indeed, subwoofers did exist back in 1976, but they weren't very common, especially in homes. Makes me wonder just what kind of a life this old beast had back in the day. Was it installed in a theater, delivering that seat shaking rumble during the mother ship scene in Close Encounters? Or was it pumping out dance classics such as the Sleeping Lions' Sound of My Heart at a discotheque? Unfortunately, I'll never know.

I had this bad boy on my workbench fully expecting the driver to need a refoam, but to my amazement it was still in very good shape. Speaking of the driver, it's a downright massive 13" woofer mounted in a heavy (65 lbs) sealed enclosure. By the way, this is a passive subwoofer, as most were before the late 1980s. To power a subwoofer like this, you'd need an external subwoofer amplifier or a passive crossover module hooked up to your main amp. As I didn't have a subwoofer amp, I used the latter.

Now, a stiff 13" driver requires serious amounts of power. I tested the subwoofer + passive crossover module with three different amplifiers: a 1992 Sony Pro-Logic AV receiver (typical home theater product of the 90s with absolutely no power supply headroom), a Marantz SR5008 home theater receiver from 2013, and Denon's flagship AVR-X7200WA. In each test, the crossover module was hooked up to the receiver's front L/R speaker outputs, and the receivers were configured to output full range audio. I set the passive crossover module to 60Hz.

The results from the first two receivers didn't exactly inspire confidence. The old Sony stereo receiver was easily driven to distortion with the subwoofer and crossover wired in. While it never went into protected mode, I feared that running it too long would cause the amp ICs to go up in flames. The Marantz SR5008, a typical 22 lbs midrange AVR, fared a bit better. I was able to get some decent volume out of the system, although listening at high volumes (-10db) for more than 10 minutes caused the receiver to go into protected mode.

Finally, I hooked the subwoofer to my Denon X7200WA, a much heavier unit with a far more robust power supply and amp section. As expected, this receiver had no problem handling the additional load. I spent a couple hours listening to music as loud as my ears could handle without any signs of trouble. However, I did notice that the Denon's two internal fans were running. Those fans never run when an active subwoofer is used!

This old skool subwoofer delivered an impressively tight and deliciously powerful low end. As most acoustic suspension designs are, this is a very musical subwoofer. I played a few tracks from Hiromi Uehara's Move and was very pleased with how nimble the speaker was, especially in the 50-60Hz region.

You may be wondering how an old, sealed passive subwoofer handles the ultra low frequencies found in many action movies. The answer is: surprisingly well, for what it is. The train derailment scene in Super 8 had my sofa shaking, although the subwoofer's response dropped off significantly below 30Hz. As expected, my duo of SVS PC12-Plus (active) subwoofers easily outperformed the old passive unit, effortlessly sending gobs of pant leg flapping energy throughout the entire room.

TL;DR: Perhaps one of the original home subwoofers, this passive unit still holds up well and is actually more musically adept than many of the active subs you'd see at Big Electronics Stores. It's not exactly friendly with entry- to mid-level receivers, as it draws so much current that most cheap receivers simply overheat and/or go into protected mode. But when you match it with a high end receiver (or even better, a powerful integrated amplifier, or a dedicated subwoofer amp), the old beast woofs beautifully!
 
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Re: Playing with a 41 year old subwoofer

Fri Sep 15, 2017 12:49 pm

Thanks for the interesting write-up!

However, I did notice that the Denon's two internal fans were running. Those fans never run when an active subwoofer is used!

Oh my, Dr. Sherlock. It seems you have we have yet to come across any fecal matter :P You obviously have an idea of how much current that thing pulls, right?
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Re: Playing with a 41 year old subwoofer

Fri Sep 15, 2017 1:03 pm

If that subwoofer is as "stiff" as claimed, an amplifier with strong current (Amps) drive will be more important than "raw power" (watts).

Saying that, I once had an amplifier that could theoretically drive 10 amps into a short circuit; it had MOSFET outputs. That old amplifier could drive anything I could throw at it, from the most complex and reactive loads to loads less than 4 ohms.

I remember subwoofers from those days needing "beefy" and "stable" amplifiers to drive them to realistic sound pressure levels. In other words, "to make them come to life".
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Re: Playing with a 41 year old subwoofer

Fri Sep 15, 2017 2:40 pm

What was the sub's nominal impedance? Most home receivers are 8 ohms, so I'm curious if the sub is just rated lower.

Regardless, nice find! I love vintage stuff. I always lament the pair of Sansui 4- or 5-ways that my cousin had back in the 80's. Those things were beasts. They were lost in a house fire.
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Re: Playing with a 41 year old subwoofer

Fri Sep 15, 2017 2:57 pm

Do you have a picture with the cover off? I honestly didn't even know they made dedicated subwoofers in those days.

I have a pair of Pioneer CS99 floor speakers from the early '70s and while they are interesting to listen to, its obvious that they were made before the time when computers were used to model speaker and crossover designs. They have FOUR tweeters, a mid and a 15" woofer. Completely unnecessary.
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Re: Playing with a 41 year old subwoofer

Fri Sep 15, 2017 3:33 pm

I found some info on the set of speakers & crossover that compliment that sub at the following link.

http://www.audioheritage.org/vbulletin/ ... -MX1-DQ-1W

Looks like the sub itself is a Dahlquist DQ-1W
 
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Re: Playing with a 41 year old subwoofer

Fri Sep 15, 2017 5:05 pm

The Dahlquist DQ-10 was designed to have this subwoofer, though after buying the DQ-10s on their own most people ran of of cash for the subwoofers.

Still, a wonderful piece of vintage audio history. Now all you need do is find a pair of DQ-10s in proper repair (good luck on that).
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Re: Playing with a 41 year old subwoofer

Fri Sep 15, 2017 6:14 pm

Very cool. I always think of 70's-and-earlier consumer audio systems as lots of highs and mids and very little low end. Would love to hear this thing in person. Have you considered building an amp into the cabinet?

Also, nice to see a fellow Hiromi fan.
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setaG_lliB
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Re: Playing with a 41 year old subwoofer

Sat Sep 16, 2017 7:37 pm

The subwoofer and crossover are both rated at 8 ohms, although a speaker this old could be dipping below 4 ohms at certain frequencies and/or volume levels. Building an amplifier into the cabinet is an interesting idea, but if I decide to continue using it, I'll probably just find an older integrated amp to power it.

Because this thing was practically made for blasting records, I brought up my old record player and played songs from Axis: Bold as Love, Abbey Road, Talking Heads 77, and George Michael's Faith. Not bad at all. The Dahlquist plays just as flat and level as my pair of SVS PC12-Plus cylinders. At moderate listening levels, I find it rather difficult to tell the two subwoofer setups apart. That's just impressive, given that the cylinders each have their own power supply and sophisticated, computerized amplifiers. The Dahlquist on the other hand is just a simple sealed box relying on an analog crossover that's sharing a power supply with the main speakers. Make no mistake, as soon as you put on a movie, the Dahlquist seems downright wimpy compared to the cylinders. But for music...I can't believe how good such a simple design can be!

It may have been designed to go along with Dahlquist speakers, but it sounds great with Philharmonic Audio speakers too.
 
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Re: Playing with a 41 year old subwoofer

Sat Sep 16, 2017 11:05 pm

I imagine that beast is far better at belting out musical notes than it is playing the nasty infrasonic square waves in modern movies.
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Re: Playing with a 41 year old subwoofer

Sat Sep 16, 2017 11:09 pm

My ~37 year old Scott speakers still sound halfway decent after all these years. I'm surprised they held up this long.
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Re: Playing with a 41 year old subwoofer

Sat Sep 16, 2017 11:57 pm

just brew it! wrote:
My ~37 year old Scott speakers still sound halfway decent after all these years. I'm surprised they held up this long.

My Polk Audio Monitor 10Bs are roughly of the same vintage.
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Re: Playing with a 41 year old subwoofer

Sun Sep 17, 2017 9:47 pm

Captain Ned wrote:
just brew it! wrote:
My ~37 year old Scott speakers still sound halfway decent after all these years. I'm surprised they held up this long.

My Polk Audio Monitor 10Bs are roughly of the same vintage.


Have a pair of Kef's with similar vintage........
 
setaG_lliB
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Re: Playing with a 41 year old subwoofer

Wed Sep 20, 2017 12:21 pm

Waco wrote:
I imagine that beast is far better at belting out musical notes than it is playing the nasty infrasonic square waves in modern movies.

IMO, the low-end of a modern action thriller doesn't sound nasty at all. Sure it's all synthetic, but at least it sounds clean with no signs of clipping or distortion.

Perhaps I'm crazy, but I've always thought that modern movie audio is some of the most well produced stuff out there. There's plenty of dynamic range; as with a good LP, you need to turn the volume up a little more than you would with a CD. It will push even the best system to its limit when the volume is cranked. Playing the movie Deadpool through the Dahlquist made its limitations clear in a way that even bass-heavy 2-ch music could not. It lacked that bone-rattling "slam" that the active subs had absolutely no problem producing.
 
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Re: Playing with a 41 year old subwoofer

Wed Sep 20, 2017 12:48 pm

setaG_lliB wrote:
Waco wrote:
I imagine that beast is far better at belting out musical notes than it is playing the nasty infrasonic square waves in modern movies.

IMO, the low-end of a modern action thriller doesn't sound nasty at all.

I meant nasty as in hard to reproduce faithfully without distortion and/or audible noise.

I have 8 15" subwoofers setup in an infinite baffle arrangement to cover it, but they're not the most musically capable lot. :lol:
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setaG_lliB
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Re: Playing with a 41 year old subwoofer

Wed Sep 20, 2017 2:19 pm

Waco wrote:
I meant nasty as in hard to reproduce faithfully without distortion and/or audible noise.

I have 8 15" subwoofers setup in an infinite baffle arrangement to cover it, but they're not the most musically capable lot. :lol:

Ah, reading comp fail. :lol:
I'm jealous. That setup must put your local cinema to shame!
 
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Re: Playing with a 41 year old subwoofer

Wed Sep 20, 2017 3:46 pm

More like I wasn't clear - I think your reading comprehension is perfectly fine. :)

It'll faithfully reproduce 5 Hz tones at pretty decent SPL. I intended it only to provide "impact" as my mains have 12" ported drivers already. :P
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Re: Playing with a 41 year old subwoofer

Wed Sep 20, 2017 4:38 pm

FWIW, this "subwoofer" indeed was intended to be used with the DQ-10. I had those back in the day, and were replaced with the original Quad ESL which overall I like better. The DQ-1W was more of a high-quality normal woofer, since the DQ-10's bass response was so anemic. From memory, it went down to about 40 Hz fine, and fell off pretty quickly thereafter.

For films where there is not much real low-frequency content, they are fine. Just don't expect to hear the much of the fundamental of the 32' stop in the Organ Symphony.
 
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Re: Playing with a 41 year old subwoofer

Wed Sep 20, 2017 6:15 pm

DrJ wrote:
I had those back in the day, and were replaced with the original Quad ESL which overall I like better. The DQ-1W was more of a high-quality normal woofer, since the DQ-10's bass response was so anemic. From memory, it went down to about 40 Hz fine, and fell off pretty quickly thereafter.

And yet the ESL-57 had no bass response to speak of.
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Re: Playing with a 41 year old subwoofer

Wed Sep 20, 2017 7:08 pm

Captain Ned wrote:
And yet the ESL-57 had no bass response to speak of.


Actually the old Quads are OK down to about 45 Hz or so as long as you don't play them too loud. And you have the right amplifier. And they are set up right in the room. And... And...

Yes, they take a LOT of diddling to get right, and even then they have their quirks. They are an acquired taste. :)
 
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Re: Playing with a 41 year old subwoofer

Wed Sep 20, 2017 8:51 pm

Waco wrote:
...I have 8 15" subwoofers setup in an infinite baffle arrangement to cover it, but they're not the most musically capable lot....

It'll faithfully reproduce 5 Hz tones at pretty decent SPL. I intended it only to provide "impact" as my mains have 12" ported drivers already. :P


Um....pics please? Think that deserves a new thread :)

And setaG_lliB that sub looks beautiful, wish I could throw a few amps/receivers at it.
 
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Re: Playing with a 41 year old subwoofer

Wed Sep 20, 2017 9:54 pm

ChicagoDave wrote:
Um....pics please? Think that deserves a new thread :)

:lol: It's an ugly pair of holes in the wall of the theater room. I got it working and I haven't taken the time to build the grills yet (magnetic to the wall). The boiler room is the "rear" of the IB baffle at ~400 sq feet. 1000 watts of power, but thermally limited on the drivers at about 500 watts. It's certainly not worth a thread of its own. :P
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