Dahlquist DQ-10's. Your thoughts on an amp for this?

[GordonW]

Ampzilla was one of the better sounding solid state amps around when the DQ-10 hit the market, but gained a rep for magic smoke problems. I'd opt for Bryson if going upper end vintage solid state, otherwise Dynaco 400 for affordable. There are other good solid state options as well of course. I'd also find a mod that looses the Motorola tweeter to make it a 4-way.

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The best I've heard DQ10s sound, in a LONG time, was in a client's system with a Crown DC300A-II ("black face") amp. Something about the character of that Crown mated with the DQ10, blended to where it just had an amazingly good balance and very satisfying dynamics.

He also had them on stands. Getting them at least 10" off of the floor, makes a big difference in clarity and tautness.

Regards,
Gordon.

 

[GordonW]

Here's the other woofer. A bit different than the other. Cone looks like plastic (the other was poly-coated paper). I don't know what the ohm rating is.

Ian
SF Bay Area

That's a Madisound 1258. It's listed in this old Madisound catalog:

http://noaudiophile.com/FieldTrip-Scott/madisound_catalog_2002-08-29.pdf

The other woofer looks a lot like a Dayton Classic DC300.

http://www.parts-express.com/dayton-audio-dc300-8-12-classic-woofer--295-320

Unfortunately, the DQ10 woofer cabinet is much too small for either.

You need to be on the lookout for a pair of Large Advent woofers. Those will drop in and work fine- they're functionally the exact same thing as the original woofers. Either the masonite-ring (early) or metal-ring (later) version will work fine.

Regards,
Gordon.

 

[Pio1980]

The best I've heard DQ10s sound, in a LONG time, was in a client's system with a Crown DC300A-II ("black face") amp. Something about the character of that Crown mated with the DQ10, blended to where it just had an amazingly good balance and very satisfying dynamics.

He also had them on stands. Getting them at least 10" off of the floor, makes a big difference in clarity and tautness.

Regards,
Gordon.

I remember folks replacing DC-300A with Ampzilla mid 1970s, dunno know much abt the MK-II Crown amps. The Mk-I was the default solid state choice before the 'zilla, and the tube revival was just beginning via ARC and W.Z. Johnson. The1970s were a great time to be around fine audio with all that was happening.

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[IanMcI]

Thank you all for the continued support! I'm certainly learning more and more with each posted reply (though, some of it is rather over my head - I do hope that time and experience, as well as input from fellow AKers, will rectify that).

It's clear that my first move must be the acquisition of Large Advent drivers. I've seen both now, and it's good to hear the opinion that the newer all-metal basket type will work well. These are at least available new. Though, it's likely I'll keep my eyes open for a donor speaker set.

And then, I'll have to off the existing drivers. I'll remove those today. Thanks GordonW for the links. The Dayton (if that's what it is - Bob Orme thinks Fisher), however, is a 4 ohm driver. There's another issue that has me scratching my head - why mix driver resistance (unless, as I think is obvious, a previous owner or tech did a sloppy job of repairing these).

I also found a Yahoo group for Dahlquist. That might prove interesting.

inscrutableo, you mention later models using yellow caps, and mine are decidedly yellow (see pic). Serial numbers on these speakers are 35098 and 35099. I do believe these are later, but how much later, let alone when they were manufactured, I don't know.

Ian
SF Bay Area

 

[Lux Man]

You should find it relatively easy to obtain a pair of Advents with the proper woofers. I just looked and here on CL there are 2-3 pairs for sale all under $140.00, I would think in your area which is much larger it would be even easier. Just buy the Advents- pull the woofers and sell the tweeters on Ebay. I may get criticized for this but let's face it, there are plenty of large advents out there. I even have a pair and my son does too.

 

[Pio1980]

There's considerable bass thru midrange magic in the properly boxed Advent woofer, small wonder Dahlquist used them for the foundation. The Advents with the Econo-vaveguide mod are literally amazing.

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[inscrutableo]

Agreed, check out the Yahoo user group, it is informative. The consecutive serial #s are always good, and it looks as though those are some of the most recent versions made (relative). The yellow caps are the later model series, and film caps, and better than the earlier version which were mostly electrolyctic which were fine for their time but they do lose spec especially after 30 years plus. So, yes, follow everyone's advice, find the proper woofers, lift them off the floor, and use proper amplification if you listen loud, and add subwoofers if you want more bass.

 

[Smallies]

I predict death by Kanye West.

 

[IanMcI]

I'm definitely on the lookout for the original, Large Advent, woofers.

And, yes, I do plan on lifting them by that amount (9", I believe) one would expect by the original stands.

Are there any issues with using wheels under speakers? These are awkward enough to handle or move, and I'm thinking I'd build wheeled stands.

Ian
SF Bay Area

 

[Freds.Bands]

The 4 ohm woofer, to be balanced with the other drivers, would require a lot of tweaking with the crossover. This is yet another incentive to acquire proper replacement woofers.

 

[elcoholic]

I'm definitely on the lookout for the original, Large Advent, woofers.

And, yes, I do plan on lifting them by that amount (9", I believe) one would expect by the original stands.

Are there any issues with using wheels under speakers? These are awkward enough to handle or move, and I'm thinking I'd build wheeled stands.

Ian
SF Bay Area

I raised mine about 13" if I remember correctly. Conventional wisdom says to put tweeters at ear level so that's what I did. I increased the std base dimensions proportionally for stability.

 

[IanMcI]

That's a nice stand! Yes, it does seem that tweeters are most often recommended to be at ear hight when one is seated. There is also an optimum, I believe, distance from the floor that a woofer should be, but I don't know how much that matters with an air-suspended driver.

When I get around to stands (after getting those woofers!), I'm sure I'll enjoy figuring out what will work best.

Ian
SF Bay Area

 

[Freds.Bands]

Looks very nice. How about stability for the speaker, esp. if on a carpet, which is top heavy on the stand?

I am going to build one out of oak stair treads and MDF (top) with 3 walnut uprights, the center one offset for torque control. I like the wrapping the base plate and will think further on this.

 

[mcspack]

Carver M400Ts

I drove mine back in the day with a pair of these classic cube amps, one per speaker, sounded fantastic, Make sure to check every few years for foam rot around woofers, rebuild as needed. I'd also just disconnect the piezos as they just sort of whine and don't really give you much good sound. Also, have a lot of low value fast burning fuses instead of the stock fuses so that your fuses burn instead of your tweeters (Use stock fuses for woofer).

 

[elcoholic]

Looks very nice. How about stability for the speaker, esp. if on a carpet, which is top heavy on the stand?

I am going to build one out of oak stair treads and MDF (top)lk with 3 walnut uprights, the center one offset for torque control. I like the wrapping the base plate and will think further on this.

Besides the white oak there's 2 or 3 layers of heavy melamine in those bases to counter the top heaviness which isn't as bad as it appears since there's not much weight above the woofer boxes. When I had the upstairs carpeted (since this picture was taken) I had them use minimal padding because I have trouble walking on soft surfaces as it is. The speakers are plenty stable as is. If they weren't I'd add a separate 3/4" sub-base with carpet spikes under them. That way the speakers could be easily slid off the spiked sub-base to be repositioned when needed.

 

[IanMcI]

I've now heard (read) a number of times that the piezo tweeter can be disconnected without harming the intended sound from these. Which is the piezo tweeter? And could it be replaced with something else without modifying the crossover?

Without compromising the design, I'd like to consider mounting the mids and tweeters on a single masonite board with a cutout simulating the space between the two boards (three, actually, as one is a tandem board) if that space is needed for the right sound.

My thought is to better manage the looks of these if I were to keep the original grills off. I'll try mocking up a drawing for what I have in mind.

I'd like to know just how precious is the math here: can these mounting boards (or the single board, if I were to go that way) be centered on the woofer cabinet? They are also offset front to back about 1/2" from each other. Any reason they couldn't be inline?

I'd like to reduce the size of these (by removing those monster grills), while maintaining their distinct sound. I really can't see how such small modifications could do any harm.

And those foam pads left, right and top of the woofer - are those sonically significant, or are they there to cushion against the grill?

Ian
SF Bay Area

 

[elcoholic]

I would caution against messing with the mids and tweeters. What makes these speakers special is the imaging and you don't want to mess with the drivers or the physical relationship of the drivers. The staggering and placement are very deliberate. That's where the DQ-10's magic is. Use the pot to adjust the brightness to taste. The lowly piezo super tweeter is mostly inaudible anyway. It adds an open, airiness to the highs. I have read of some that have replaced the stock tweeter with AMTs or Vifa 1" dual ring tweeters and been happy with the results. In these cases most leave out the super tweeters because they'd be redundant.

If you like the sound of restored DQ-10's, but want a smaller package try the DQ-20's.

 

[dcmfan]

I'd like to reduce the size of these (by removing those monster grills), while maintaining their distinct sound. I really can't see how such small modifications could do any harm.

As elcoholic said, I'd tread carefully here. The DQ-10s touted phase and time alignment of the drivers (with their smaller baffles and staggered placement) which is why a speaker with 5 drivers sounds so unified.


In order to minimize undesirable effects from diffraction, each driver has been separately mounted on the smallest possible baffle, whose dimensions were determined by the frequency range of the passband. This is directly opposed to the standard practice of mounting the drivers on one relatively large baffle.

The mounting method used in the Phased Array also makes it possible to incorporate time-delay correction through relative front-to-back positioning of each element.


--Source: http://www.hifiengine.com/manual_library/dahlquist/dq-10.shtml

 

[IanMcI]

I don't know that I'd ever seriously consider modifying these, but as an exercise for the fun of it, I mocked up a few images. I took the photo of the room with stock DQ-10's from the internet (I don't know whose room this is - sorry if it's an AK member. Just wanted a canvas to show how such a modification might make a difference). I then "swapped" them out for those I mocked up. I kept the dimensions the same, so the representation should be pretty accurate.

In drawing these, I took measurements, of course, and found that the dimensions of the stock DQ's are not, I think, terribly fussy; measurements are to the 1/2 and 1/4 inch - no 1/16, 1/8 inch finesse. The setback of the taller set of masonite boards seems in response to the curvature of the original grill.

I made what I think are very slight adjustments, with two being the most obvious: one, the adjustment of relative heights of the two masonite boards (one being two boards top and bottom) - I brought them close enough in size to allow the one, single dimension board, adding back in the effective separation between the two as a vertically-oblong cutout; the other, and it may be the more telling, is the centering of the single masonite board on the LF box.

Again, just for fun, but instructive, in that my measurements seem to show, not a terribly precise arrangement of drivers, but rather a fairly pedestrian response to the pressures of manufacturing efficiencies.

By the way, the mauve background of the larger image of the mocked up speaker, represents the profile of the original grill.

Ian
SF Bay Area

 

[IanMcI]

And then, just because I'm at it, and in homage to the origins of the name: