the good, the bad, and the ugly (Yet another Dahlquist DQ-10 restoration thread)

[DOBIEGUY]

3B or4B?
I’ve got a 3B since new, chrome handles and curley cord. Tens of thousands of hours of service and
as original as the day it was built.
Able to double down into a 4ohm load, I’m sure that Bryston well have those subs slamming.
What issues are you expecting with it? .

 

[Cornholio]

3B or4B?
I’ve got a 3B since new, chrome handles and curley cord. Tens of thousands of hours of service and
as original as the day it was built.
Able to double down into a 4ohm load, I’m sure that Bryston well have those subs slamming.
What issues are you expecting with it? .

So it's a 3B, judging by the board markings on the inside it would appear to be a 3rd generation/revision, circa late 87/early 88 (honestly a bit young for my taste, but I admittedly have an ever growing fondness for Bryston since I picked up that 1B pre-amp, their equipment is built like a tank).

So I haven't tried testing it yet, but the seller stated that:

"seems to pass signal through both channels"
This could be as simple as they had the selector switch flipped from stereo to mono.

"Left channel clipping light is always lit red"
The listing photos show this as well, could be a number of things.

"Right channel heat sinks seem warmer than left"
This also could be a number of things.

So far I have popped off the top cover and done a quick visual inspection and the only thing that really stands out is some apparent heat damage on the I/O board, however it's in a spot that doesn't seem to have any obvious component as a cause, could have just been an assembler getting a bit over-zealous with the soldering iron.

 

[onwardjames]

@Cornholio I don't know how I missed this thread, but let me throw my praise onto the heaps you have already accrued.

Me, I'm a romantic, and did a restoration nearly as in-depth as this one on my Epi Model 20's, which were absolutely trashed.

It brought me a heretofore unknown sense of pride. I expect this will do for you in the same manner.

Wishing you all the best in getting these across the finish line, along with the Bryston, etc. Splendid work thus far.

 

[DOBIEGUY]

The fact that it passes a signal through both channels is a good sign. The clipping LED is an issue for later.
Get yourself a point and shoot laser thermo gun and take the guess work out of temp differences.
Don’t jump the gun and start replacing parts. There just might be nothing seriously wrong.
Also, can’t speak for your model but mine would not tolerate anything but the correct fuses.
These amps are built for the ages.

 

[Cornholio]

The fact that it passes a signal through both channels is a good sign. The clipping LED is an issue for later.
Get yourself a point and shoot laser thermo gun and take the guess work out of temp differences.
Don’t jump the gun and start replacing parts. There just might be nothing seriously wrong.
Also, can’t speak for your model but mine would not tolerate anything but the correct fuses.
These amps are built for the ages.

In terms of the Bryston I have no plans of doing a complete rebuild (as opposed to the Ampzilla I am working on, but the Ampzilla was sold as a kit, and my intentions are to treat it as such, taking liberties to upgrade components, save for where it calls for no substitution, and boy oh boy am I losing control when it comes to the Zilla rebuild... but that's a different story that belongs in my Ampzilla thread) save for the possibility of replacing the 6 electrolytics on the amp boards and maybe the four big filter caps, but even then I will likely try and use identical components (my first observation after removing the top cover of the 3B was "dang, they used really high quality stuff here" and honestly I wish I would have acquired the 3B a month ago, as I have spent a great deal of time speccing out components for the Zilla, researching manufacturers and lines, only to find that the engineers at Bryston came to nearly identical conclusions back in 87 for the 3B as I have today for the Zilla, but I digress) as I bought the 3B because I wanted a 3B, not a modded custom job that just looks like a 3B on the outside, and I wanted its own unique sound, as designed by Bryston. Heck, I am even considering the possibility of just sending it in to Bryston (ha ha, there's only a minuscule chance I will do that though, how else will I learn how to troubleshoot the design?) but really the focus will be on repairing and ensuring function as designed.

 

[donprice]

Heck, I am even considering the possibility of just sending it in to Bryston...

That would free up time focus on what you already have cooking. Don't you have some wires to wrap in veneer or carbonite or something

Is the Bryston too nice to risk a repair gone bad?

 

[Cornholio]

That would free up time focus on what you already have cooking. Don't you have some wires to wrap in veneer or carbonite or something

Is the Bryston too nice to risk a repair gone bad?

Well, I have been too busy with other stuff to look into the Bryston more, however I am confident enough in my abilities to try it either way!, worst case scenario I find out I need (read: an excuse to buy) a new piece of test equipment, what a tragedy that would be!

 

[Cornholio]

Hi folks, just wanted to give a quick update since it has been a while, I am still working on the DQ's (okay the amp stuff has been a major distraction) and hopefully sometime in the next few weeks I will get the spray booth designed and built and get moving forward again! This means I'll finally be getting on to the really fun stuff (not that it hasn't been fun so far, it's just been mostly woodworking) the drivers and electronics!

 

[Cornholio]

Hi all, just wanted to pop in for a quick update-- I decided a couple months back that it would be best to work on the Ampzilla project until the temps cooled off and humidity levels went down here in DC, and we're finally getting there!

Hopefully should be firing on all cylinders again on the DQ's again soon!

 

[Aptone]

I decided a couple months back that it would be best to work on the Ampzilla project until the temps cooled off and humidity levels went down here in DC, and we're finally getting there!

You are Mr Delayed Gratification. Looking forward to more updates!

 

[onwardjames]

Any news?

 

[Cornholio]

So I paused work at the end of the summer when I realized that nothing I had at the time could drive the DQ-10s.

I have spent the time since on my Ampzilla rebuilds, and I am nearing completion of that project, and I have begun thinking about the DQ-10s again.

The main hold-up currently is that I need to spray finish the boxes and baffles before moving on, and in order to do that I need to build a spray booth in my apartment, which shouldn't be that bad to do, but it will take time and money. With that said, it's the next major undertaking that will happen for all of my projects, as I especially need to finish the speakers before the intense humidity returns to DC.

I haven't stopped work entirely, though, as I have over the past few months also been buying parts/supplies to complete the speakers.

Another potential holdup is that, due to my Ampzilla rebuild turning into rebuilding two entire units, I am now toying with the idea of bi-amplifying the DQ-10s since I have now 4 matched channels to work with. It's been an internal debate though, as part of me wants to use the second Ampzilla to drive the DQ-1Ws as soon as I rebuild them, but on the other hand I also picked up an older Bryston 3B in need of a tiny bit of work (it's been tested, sounds alright, however there are some obvious issues that need to be addressed) that I originally intended to use for the subs, and might still go that route (to be honest, I don't even know if I can power that much equipment, as my lights flicker and dim as it is in my apartment when I power up a single Ampzilla, I haven't dared trying to fire up both of them at the same time yet, let alone both Ampzillas and the 3B!). Bi-amping the DQ-10s also introduces extra costs when it comes to connectors especially (I have unfortunately expensive taste in connectors), as it would require four additional binding post/banana plug pairs, and at the price I have bought the binding posts/banana plugs so far that could be a bump up in costs of $200, and I haven't even started buying I/O connectors for the DQ-1W...

Stay tuned though for further updates, as I am now doing listening tests on my new Ampzillas, I will soon be shifting my focus over to the DQ-10s (I am currently doing listening tests on a pair of mint OLAs that I bought originally to gut for the woofers to go in the DQ-10s, but they ended up being in such good condition that I don't think I have the heart to ruin them, and they sound pretty good as is, too, at least to my untrained ears!)

 

[ranukic]

Awesome thread! How have things progressed since your last post?

 

[Yodathedog]

Looks like he’s off planet.

 

[mahunt]

While we wait for the OP to return narrating his excellent adventure, I'll try to add a little to the Dahlquist DQ-10 collective.

I also own a pair of these awesome speakers (47716 and 47719, L and R respectively). I too was confronted with similar issues of repair, bass augmentation of the lower octave and what to use for amplification (gotta generate 200w per channel to drive these things). If you take a gander at my avatar you can see 44719, a Beogram 4004 sporting a SoundSmith CL+ cartridge and my venerable Yamaha RX-V1.

I recently had some trouble with the left speaker as it, in the last year, occasionally needed a Fonziesque fist boink to resume playing, due to either a solder ring crack or other such issue. I decided to disassemble the speaker and then check the components plus reflow all the solder connections.

The speakers were brought back into service by me about 20 years ago (has it been so long) with new bass speaker surrounds to replace the fully disintegrated originals and a Regnar recap. Both repairs went well and the speakers entered regular service.

DQ-10s are easy to appreciate, for sonic reasons well attested to here at AK and other sites. But they do need help on the bottom end and I used a Parts Express powered sub-woofer speaker that came in kit form. I was looking for something that could pull double duty by being both musical (tight) and able to provide reasonable sub-bass effects (low and punchy) for my Home Theater. I settled on a 16 x 18 x18 prebuilt; adding the 12-inch speaker and their KG-5150 amp board.

This setup (DQ-10s, RX-V1 and powered sub) worked nicely for listening to stereo music and watching movies for about 20 years until (after retirement) I decided to try and fully power the speakers with a 200w amp. I did read about the Ampzilla as it seemed to be the perfect solution to the Dahlquists power needs back in the day, but I couldn't afford that choice then or now. Being a Yamaha fan, I searched for and eventually found a M-70 which was in good condition and sonically matched my other gear. I ended up recapping the M-70 with help from this website (posted in the amp section).

My advice to the OP is you will be rewarded for your efforts and you can spend more for decent speakers, but you won't find a better sounding value than the DQ-10.

 

[AudioCarMan]

This setup (DQ-10s, RX-V1 and powered sub) worked nicely for listening to stereo music and watching movies for about 20 years until (after retirement) I decided to try and fully power the speakers with a 200w amp. I did read about the Ampzilla as it seemed to be the perfect solution to the Dahlquists power needs back in the day, but I couldn't afford that choice then or now. Being a Yamaha fan, I searched for and eventually found a M-70 which was in good condition and sonically matched my other gear. I ended up recapping the M-70 with help from this website (posted in the amp section).

My advice to the OP is you will be rewarded for your efforts and you can spend more for decent speakers, but you won't find a better sounding value than the DQ-10.

Yamaha RX-V1 and Dahlquist DQ-10, you just described my audio setting. Did you notice much of a difference when you added the Yamaha M-70? Was it worth it? I might be looking into that in a few years when I move to a bigger place.

 

[mahunt]

As the M-70 is a Natural Sound amp, it matches the sonic style of the RX-V1 seamlessly (in my opinion). It's one of the reasons I wanted a Yamaha amp. The clarity from the speakers seems improved to me with amazing detail, even at very low listening levels. Some folks take issue with Natural Sound, but if you are already a Yamaha admirer, you won't be disappointed.

The 200 watt M-70 amp does indeed drive the Dahlquists higher than the 110 wpc RX-V1.

Frequency response is similar (same upper limit), with expanded range at the bottom (1Hz vs 10Hz). The signal to noise stat is improved with the M-70 being 124dB vs 86dB. THD is also similar with .002% for the amp and .015% for the receiver. The older Yamaha amp is technically better than the newer receiver.

My listening room is largeish, 24 x 44 with a 15 foot vaulted ceiling. The speakers themselves are 16 feet apart. I have a bit of room to fill with sound if I want to listen to louder music (rock out) or Home Theater. The M-70 has more power and seemingly more detail than the already very detailed RX-V1.



You didn't mention WHAT you were looking for; louder, clarity, or something else.

The M-70 came to me in very good cosmetic condition, but I still did a recap and changed the speaker connections from the odd twist style to conventional 5-way (a must in my opinion). The disco era LED power display brings a smile, but is usually selected off as it would visually distract from movie viewing.

Having written this, I have wondered about the next more powerful Yamaha amp; the M-80/85. The M-80/85 offers Natural Sound, but with a 50 wpc bump in total power. Even though the Dahlquists are rated at 200 watts, I'm pretty certain they would use the extra wattage with no issue. Getting a decent M-80/85 would have cost more than twice as much for the extra 50 watts. I very much like the M-70 and having acquired it for $400 2 years ago, I believe it represents a good value for quality power vs price.

 

[AudioCarMan]

M-70 is a Natural Sound amp, it matches the sonic style of the RX-V1 seamlessly (in my opinion). It's one of the reasons I wanted a Yamaha amp. The clarity from the speakers seems improved to me with amazing detail, even at very low listening levels. Some folks take issue with Natural Sound, but if you are already a Yamaha admirer, you won't be disappointed.

The 200 watt M-70 amp does indeed drive the Dahlquists higher than the 110 wpc RX-V1.

Frequency response is similar (same upper limit), with expanded range at the bottom (1Hz vs 10Hz). The signal to noise stat is improved with the M-70 being 124dB vs 86dB. THD is also similar with .002% for the amp and .015% for the receiver. The older Yamaha amp is technically better than the newer receiver.

My listening room is largeish, 24 x 44 with a 15 foot vaulted ceiling. The speakers themselves are 16 feet apart. I have a bit of room to fill with sound if I want to listen to louder music (rock out) or Home Theater. The M-70 has more power and seemingly more detail than the already very detailed RX-V1.

View attachment 2569099 As the

You didn't mention WHAT you were looking for; louder, clarity, or something else.

The M-70 came to me in very good cosmetic condition, but I still did a recap and changed the speaker connections from the odd twist style to conventional 5-way (a must in my opinion). The disco era LED power display brings a smile, but is usually selected off as it would visually distract from movie viewing.

Having written this, I have wondered about the next more powerful Yamaha amp; the M-80/85. The M-80/85 offers Natural Sound, but with a 50 wpc bump in total power. Even though the Dahlquists are rated at 200 watts, I'm pretty certain they would use the extra wattage with no issue. Getting a decent M-80/85 would have cost more than twice as much for the extra 50 watts. I very much like the M-70 and having acquired it for $400 2 years ago, I believe it represents a good value for quality power vs price.

Thank you very much for your detailed comment.
In regards to your question, I look for clarity over anything else. To me this is by far the most important aspect, at least as of today, considering that I live in a small apartment. Once I finish my degree I will move to a bigger place and probably but an amp.
I like the Yamaha sound a lot. Locally I see a lot of Crown amps (CE 1000 and CE 2000) being sold for $150 and $250, but I might go with the Yamaha M-70 in the future. I don't think that there will be a ton of differences sound wise between the M-70 and the M-80, so I will probably save the extra $.

By the way, your living room looks great. Nice design. You must enjoy the views with the lake!

 

[Bkphoto]

These are wild speakers…to the untrained eye they are home made, cobbled together spare parts….it’s what they look like….

but they do sound pretty good, although I’m not a fan of the whizzer (sp?)

 

[mahunt]

The clarity aspect of the Dahlquists and the Yamaha amp is a wonderful phenomenon.

Usually one turns up the volume to hear more, but in this instance you already hear more at very low volumes. Vocals, individual instruments, effects, whatever are all represented at the lowest volumes with great clarity, turning up the volume just makes it louder.

The aural sensation is a little difficult to describe.