For starters, I would think DQ10's should not be mounted on a wall for best performance.
They are excellent speakers and image well, due in part to their semi open baffle design.
The manufacturer supplied them with low stands like the original Quads, and for an extra charge, slightly higher stands.
So in either case up off the floor and typically a least a few feet from the walls.
From there I don't know how you would "stack" them, but this has been addressed in other threads for Quads and Magnepans. I would guess that stacking them vertically like Quads might be best.
The DQ1W was a matched subwoofer which could be used singly or in pairs, where Dahlquist also made an easy to adjust active crossover you might also find on the used market.
That made it easy enough to use one amp for the woofer and another for the panels, but I will let others comment on vertical or horizontal biamping for two sets of panels alone.
Good luck - classic speakers well worth the effort.
On the wall!!!! Blasphemy. DQ10s are not moose heads or flat-screen TVs. Forget the second pair until you get the first pair positioned correctly.
YUK....get them off the wall
The wall is the right place, DQ10s should be seen and not heard! LOL You can power them both with the same amp IF it will handle low impedance loads. Running them in parallel will halve the impedance the amp sees, not all amps will be happy with this. Why do you want to use 2 pairs, more volume? A sub for one pair may be more practical. Electrostatics and planar are doubled to increase volume and bass, cone speakers are more problematic as they will usually play loud enough and the multiple drivers will interfere with each other to a greater degree.
I agree with the other posters who recommend getting them off the wall. They generally will like being in or near the cardas recommended locations - see cardas' web site.
I had two pair, twice. The best sounding happened to be side by side on stands that raised them about 18-20 inches off the floor. Each pair was driven by an Audio Research D76A, which were driven by an Audio Research SP3A1. The system was one of the best I've ever heard - open, airy, played deep and tight and loud with excellent transient response, detailed but pleasing highs. Rock and roll was close to perfect. If I could get that sound back I'd never want to make another tweak.
I later had a 2nd double pair that I mounted in custom steel frames so that they were vertically stacked rather than horizontally side by side. This configuration was visually more impressive but sonically not as good, but it could have been different/lesser electronics and/or less desirable room acoustics.
In any event, DQ-10s are classics and worth every penny if you find good ones on the used market. 2 pair has the potential to be a knockout.
I have 6 pairs of DQ10s set up. I used some industrial strength metal racking obtained from Lowe's and modified them to accommodate all the Dqs. They are essentially stacked upon each other in three sets of rows. I am unable to post a picture here. If you send me an email to firstname.lastname@example.org, I'll send you a picture and schematic of how they are hooked up. Essentially l amp is pushing 2 sets of DQ10s. Your amp must be able to handle the split load. Good luck.
How do they sound?
You could always use a Speltz Autoformer to bring the impedance of two pairs operating off of one amp back up to double or even triple the impedance of a single pair.
Years ago, I heard 2 sets stacked, the top set was upside down. The guy made a bracket that molded around the top edges of the bottom set and the top set slid into the bracket, then had screws or bolts go through the side of the brackets into the speakers that stablized them fairly well. in this case, 2 sets were an improvement over 1 in almost all area's.
Find a pair of Audio Research D-76A's. I have a customer who had modified DQ-10's. I refurbished his amp and it sings!!!!It sounds better than when it was new because the new caps are much better than the stock ones.
Timlub or anyone remember who suggested the stacked DQ10s?? Someone marketed the metal brackets you are talking about and the reviews were very favorable. I can't find it on the internet. I remember when Mark Levinson sold his stacked DQ10s on ebay, that is when I researched it and pondered the idea. Hifigeek, how did your customer modify his DQ10s? I have added 12 inch Infinity polypropylene "car" woofer :)..fits perfectly in hole...little close in depth.... and Heil midrange driver and infinity tweeter to replace piezo.... love them. My friends think I am crazy...but $500 total in speakers and I am having fun. FYI, I compared Double Dyna to D76A on these speakers and it was amazing how similar the midrange was on two completely different designes....Just like Harry Pearson said. Also, I just read a Jim Bongiorno interview where he stated he "HATED" tubes...love it. I had to turn the bias up (Enid Lumley told me what blue pot) ;) on the Dynaco to make it sound more like the 76A....The Dynaco ran HOT!! Well, back to trying to bias the ARC Classic 60...having fun again.
Oh, DQ10s on the wall... I have several comments, but I shouldn't.....but thanks to the post anyway.
I had a nice pair of DQ-10s in the early-to-late 1980s and really liked them. About 1983, I installed the Randall Research modified crossover and drivers with nice results. With today's crossover components, wire and drivers, I would imagine that you could assemble a really nice pair.
Properly powering all four speakers with a single amp would be a tall order, to be sure. Get them away from all walls! not behind or on sides. Properly set up, they will image like crazy, with light, airy highs. I can only imagine how nice four would sound.....
Apfdirtdoctor...He disconnected the Motorola Piezo Tweeters and put all new film caps in the crossovers. I think he rewired them as well and replaced the woofers. OMG Enid Lumley. There's a name I haven't heard in decades.
Sorry Apfdirtdoctor, I didn't know of any articles. My old friend might have indeed read it. This was around 1980 to 1981.
I thought Mark Levinson stacked Quads, not Dahlquists.
As in HQD for Hartley, Quad and Decca.