I believe this is correct. Advent and Dahlquist may have bought the components for their woofers from the same source, but they're not completely identical.
In reply to Anderson, you are right they were 8 ohms which is a difference between 4. I am using 8 ohm drivers (JBL), just to let you know, and they are an 8 inch rather than a 10 inch. I have kept the same array though. And I was going to post my capacitor, resistor and inductor values but have decided not to, due to the feedback from other people wanting to buy the ones I have created. I have figured out after trial and error how to tone down the piezo tweeter so it's not so harsh and actually pleasant to hear. Hard to believe but I did it. The midrange is outstanding! The sound image is incredible. Its hard to explain how good it sounds, but your ears don't lie to you. I can't believe I made something that sounds so good. Ive demo'ed them on descent and pristine amps from kenwood to McIntosh, tube and solid state. They are a dream come true. I would be glad to demo them to you if you're ever in Pismo Beach, CA. Let me know. In the future I plan to make more and sell them on line. It'll take a few years for me to get my business going but I'm working on it already. Plus I'm building altec 210 split cabs and smith horns. 
I have a pair of stacked DQ10's on stands which I designed and made myself. I'm driving them with a Phase Linear 400, but you are right in supposing it's not enough power. Looking for a larger amp, or a second PL400 to augment the juice. Sound is airy, transparent. Vocals, woodwinds and horns are in the room with you. Not the best speakers to jam out to with loud rock or special effects (I've blown the woofers more than once getting into albums such as The Wall or even early Steely Dan.) These speakers have the uncanny ability to make you think you are listening to a new mix down of songs you've heard hundreds of times on conventional speaker systems. You'll hear stuff you've never heard before, such as shakers, synthesizers, echos, musicians breathing and so forth....)
Scottie
An externally hosted image should be here but it was not working when we last tested it.
Scottie
Since I started with the audio hobby in the early seventies I have gone through at most at least thirty speaker systems, many of them built by myself, horn systems, most well known systems such as Quad, DQ10, Magnepans, Wilson, Infinity, you name it. Out of all systems I have had I kept the Dahlquist DQ10's and they quickly became my favorite speakers and for me a lifelong hobby. It's now been more than thirty years and counting and I am still improving and tweaking my system.
My speakers were already mirror imaged and my first mod was to replace all mylar caps with polypropylene caps, better wiring, better damping material, bracing the box, bypassing the fuse etc.
My second mod was to buy the Sequerra HF-1 ribbon tweeters (highpass at 3.5 KHz, 24 dB filter), especially designed for DQ10 and to be mounted on top of the grille. In the process I disconnected the Motorola super tweeter and the Peerless tweeter. This mod made an already great speaker substantially better, the sound became more spacious, dynamics improved and the highs substantially better.
My next step was to find a midrange dome that could replace the mediocre 1.5" Perless midrange driver. Over time I went through at least 20 candidates I could find on the market. Finally I found the perfect replacement, the Dynaudio D54 2" dome midrange. Since its frequency range is shorter than the Peerless midrange I had to mate it with a ScanSpeak tweeter (took me a few years to find ) to make the transition to the ribbon tweeter seamless. This replacement required designing a new crossover to make the system sound right. My home audio laboratory with a computerized Clio measurement system and a crossover optimization system was here a great help but finally many hours of listening was required to make it sound right. This step took more than 15 years to realize.
At the moment I am trying to find a better alternative to the cheap 5" Philips Mid-Woofer. Although I have experimented with many better sounding drivers with less distortion and more dynamic range I have yet to find another driver that I can integrate into the system seamlessly, even with a redesign of the crossover.
The system has now a huge and expansive sound field (both width and depth), instruments and voices are projected at the proper height and with pinpoint accuracy. Voices sound natural and transparancy rivals most electrostatic systems. At this point my DQ10 system, including Entec subwoofers, is my favorite system of all times and I have yet to find anything that comes close.
My speakers were already mirror imaged and my first mod was to replace all mylar caps with polypropylene caps, better wiring, better damping material, bracing the box, bypassing the fuse etc.
My second mod was to buy the Sequerra HF-1 ribbon tweeters (highpass at 3.5 KHz, 24 dB filter), especially designed for DQ10 and to be mounted on top of the grille. In the process I disconnected the Motorola super tweeter and the Peerless tweeter. This mod made an already great speaker substantially better, the sound became more spacious, dynamics improved and the highs substantially better.
My next step was to find a midrange dome that could replace the mediocre 1.5" Perless midrange driver. Over time I went through at least 20 candidates I could find on the market. Finally I found the perfect replacement, the Dynaudio D54 2" dome midrange. Since its frequency range is shorter than the Peerless midrange I had to mate it with a ScanSpeak tweeter (took me a few years to find ) to make the transition to the ribbon tweeter seamless. This replacement required designing a new crossover to make the system sound right. My home audio laboratory with a computerized Clio measurement system and a crossover optimization system was here a great help but finally many hours of listening was required to make it sound right. This step took more than 15 years to realize.
At the moment I am trying to find a better alternative to the cheap 5" Philips Mid-Woofer. Although I have experimented with many better sounding drivers with less distortion and more dynamic range I have yet to find another driver that I can integrate into the system seamlessly, even with a redesign of the crossover.
The system has now a huge and expansive sound field (both width and depth), instruments and voices are projected at the proper height and with pinpoint accuracy. Voices sound natural and transparancy rivals most electrostatic systems. At this point my DQ10 system, including Entec subwoofers, is my favorite system of all times and I have yet to find anything that comes close.
This is an exciting thread for me. I sold Dahlquist in the early 80's. I owned a pair of DQ-10s and powered them with a Hafler DH-500 and that worked well. I sold them off for financial reasons after about two years and have missed them since. I guess the challenge in my mind is the huge number of raw drivers that might be candidates. There were more expensive drivers available then too but Dahlquist chose THOSE. A Motorola Piezo? Really? End result was that they sounded great to me. Truthfully, this sounds like a great project, using... scratch that... REQUIRING every tool available to the DIYer to optimize. A great learning exercise. Thanks for bringing this up
In case this topic is of interest still:
The best amp I ever tried on them was the Threshold Stasis-3. Beat various Haflers, Dynaco's, Ampzilla's of the time. Also a JVC-UA tone arm with a FR-3Mk1 cartridge on an Oracle, I had a mod'd PS Audio pre-amp and FR step up to start, and an ARC SP-15 with a Carniegie cartridge later.
I ended up building new woofer cabinets with the woofer along the top edge, volume equal to the old box, crossover and wiring external, and lined up the drivers vertically using metal mounts over the boards they were mounted on. I understood the idea behind that alignment and the boards, but believe me they voiced much better vertically, and nearly naked.
I had to realign the voice coil to one of the low mid drivers. replace the cheap old caps with Solen's (better at that time).
I did replace the piezo with a JVC ribbon for much sweeter softer treble.
I had actually cut down the grill covers to retain the style over the thinner facing of the woofer. I also got rid of the metal screening, and cut down the wood so the drivers could breathe to the side.
Obviously I spent years and dollars, but learned a lot. Much more recently made a pair of Triangle Celius 202's from annoying to excellent, rebuilt a pair of Pro Ac Tablette II's
The best amp I ever tried on them was the Threshold Stasis-3. Beat various Haflers, Dynaco's, Ampzilla's of the time. Also a JVC-UA tone arm with a FR-3Mk1 cartridge on an Oracle, I had a mod'd PS Audio pre-amp and FR step up to start, and an ARC SP-15 with a Carniegie cartridge later.
I ended up building new woofer cabinets with the woofer along the top edge, volume equal to the old box, crossover and wiring external, and lined up the drivers vertically using metal mounts over the boards they were mounted on. I understood the idea behind that alignment and the boards, but believe me they voiced much better vertically, and nearly naked.
I had to realign the voice coil to one of the low mid drivers. replace the cheap old caps with Solen's (better at that time).
I did replace the piezo with a JVC ribbon for much sweeter softer treble.
I had actually cut down the grill covers to retain the style over the thinner facing of the woofer. I also got rid of the metal screening, and cut down the wood so the drivers could breathe to the side.
Obviously I spent years and dollars, but learned a lot. Much more recently made a pair of Triangle Celius 202's from annoying to excellent, rebuilt a pair of Pro Ac Tablette II's
Hi ! plese forgive me if i take up this old thread
I listened to the DQ10 driven by Audio Research electronics many many years ago for the 1st time ... i guess it was in the 1978 ?
I was immediately hit but what i still think is the most fascinating effect with stereo ... a nice 3D soundstage.
As the drivers used are very nice but quite "normal" i tried to study the crossover ... without any real understanding of it
My question is the following
I have found a FR of the Philips midrange cone in another thread
https://files.diyaudio.com/forums/gallery/data/1935/medium/fr.jpg
It goes unbelievably flat up to almost 10kHz
In the DQ10 if i am not wrong is cut at about 1kHz ?
Why on the earth do not stretch it up to let's say 3kHz ? in this way just a very good dome tweeter would be needed to cover the remaing highs
I mean ... why not make a 3 ways DQ10 ?
I am sure that the cabinet is not the secret of its so coeherent sound .... probably the xover is but i am very ignorant on the matter.
When i see so many drivers i always wonder if they are all really needed And i am skeptical
Thank you very much and best regards,
gino
I listened to the DQ10 driven by Audio Research electronics many many years ago for the 1st time ... i guess it was in the 1978 ?
I was immediately hit but what i still think is the most fascinating effect with stereo ... a nice 3D soundstage.
As the drivers used are very nice but quite "normal" i tried to study the crossover ... without any real understanding of it
My question is the following
I have found a FR of the Philips midrange cone in another thread
https://files.diyaudio.com/forums/gallery/data/1935/medium/fr.jpg
It goes unbelievably flat up to almost 10kHz
In the DQ10 if i am not wrong is cut at about 1kHz ?
Why on the earth do not stretch it up to let's say 3kHz ? in this way just a very good dome tweeter would be needed to cover the remaing highs
I mean ... why not make a 3 ways DQ10 ?
I am sure that the cabinet is not the secret of its so coeherent sound .... probably the xover is but i am very ignorant on the matter.
When i see so many drivers i always wonder if they are all really needed And i am skeptical
Thank you very much and best regards,
gino
I had a pair and always felt the Philips 5060AD and midrange dome made this speaker what it was...as to the dome a believe a HiVi has been used as a substitute. I wonder if a SB Satori paper cone could replace the Philips? Another thought could be stealing the mid+ tweeter from the HiVi 3.1 diy kit and incorporating them as the mid/top end.
"About 3 years after Saul Marantz sold his company to Superscope Inc, he discovered another great talent who was obsessed with designing the perfect speaker. The man by trade was an engineer in the aerospace-industry and had played a key role in the development of the lunar landing module. His name was Jon Dahlquist and after hearing the prototype DQ-10s, Marantz sensed his greatness and immediately bought 49% of Dahlquist."
https://auralfetish.com/pages/dahlquist
https://auralfetish.com/pages/dahlquist
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It goes unbelievably flat up to almost 10kHz
In the DQ10 if i am not wrong is cut at about 1kHz ?
Why on the earth do not stretch it up to let's say 3kHz ?
Jon Dahlquist was aiming for widest dispersion possible I would think. Assigning each driver strictly to its geometrically best off axis frequency range. Hence the five way.
Hi thank you very much for the kind and valuable advice. I have a good friend sick of vintage speakers He swears that that midrange is very very good indeed. I am not saying that the original could be beaten ... i do not want to sound crazy. But using only the Phlips to cover all the midrange up to lets say 3kHz would provide a coeherence in the sound that only a single driver can provide
I know designers They are genius but also sometimes they tend to complicate things I think that some kind of effort should be spent to make things as simple as possible
I intend to search for that driver in the market for a prokect i have I am pretty sure that it can be found in some vintage speakers that come from almost nothing Of course conditions could be bad
I do not think that the dispersion is the key thing This to me is a multiway speaker acting as a single driver
I do not know if someone know better but the DQ 10 have a striking similarity to these
https://cdn.shopify.com/s/files/1/2197/6387/products/IMG_4867.jpg?v=1638753359
it could be that they were used as a reference for the sound ?
When i listened to them i was perfectly in the center in the swet spot ... i pushed away someone who wanted to take my place
1st 3D soundstage experience in my life I have never heard something like that before Virtual reality at least from a sonic point of view
Clearly from a dynamic point of view a dome midrange is faster than a heavier cone .... but that Philips must be very good indeed
And the xover needs some rework
From what i understand the following DQ20 (a 3 way by the way) did not have the same success ?
https://img.usaudiomart.com/uploads...kers-excellent-condition-woofers-refoamed.jpg
Actually i like their shape so much better
Never heard them
But it is... Dr Linkwitz is much better than me in explaining this. A single driver should be better than a multi way in everything except a wide soundstage. Physics point to a 4 or 5 way for good off axis response. The question is how do you get the crossover done right.