I posted much of this elsewhere, but probably should have posted it here first, since there seem to be a bit more ifolks nterested in Dahlquist DQ-10's here at ST. So, here goes...

I recently replaced the peizo super tweeters in my DQ-10's, finally succumbing to those who felt that such a cheap and cheesy driver had no place in such an otherwise fine loudspeaker. Still, in all the years I've owned these speakers (actually 32 years!), I've never had a problem with the piezos, since, as Jon Dahlquist himself had stated, they don't even begin to work until 12,000HZ, and most people would never hear much difference between the piezos or another driver at those frequencies.

The replacement driver I purchased is an Eminence APT-80 super tweeter, which is available from Parts Express for about $25 each. Piezos from Parts Express are available for an amazingly low price of only $1.44, and after replacing a factory original with one of these Chinese-manufactured cheapies, I have to say I couldn't tell the difference between it, and the still working factory-installed original in the other speaker.

The Eminence drivers have a plastic diffusion lens with the identical mounting dimensions as the piezo, but there's nothing else similar between the two: the Eminence appears as if it's a compression driver (I'm only saying that it "looks" like one, because I can't say with any actual knowledge that it is), and it has a very substantial magnet on the back, which, of course, the super lightweight piezo doesn't.

So, did it make a difference? The answer is, "Yes, it did, but it wasn't night and day." What I perceive as the difference isn't an increase in upper end detail, or any added "sparkle," but a new sense of air and space around certain instruments and voices. Overall, the speaker sounds a bit smoother, but only slightly so. While I recommend such an upgrade, I must admit that, since the difference is so small, that Jon Dahlquist knew what he was talking about.

Then too, there is the fact that I am almost 65 years old, and may not even still hear anything above 12,000HZ. I know that when (with the grilles off) I placed my ear right up against the new driver, I wasn't aware of anything coming out of it, but when covering up both the tweeter, and then the super tweeter with my hands, there was a noticeable difference in sound. Of course, covering up the tweeter cuts off almost all high frequencies, but even after doing that, I wasn't aware of anything coming out of the super tweeter until I covered it up also.

I guess I have to say that I now have "upgraded" DQ-10's, or "modified" DQ-10's, as they are no longer in their original state. Paying $139.50 to have each woofer rebuilt by Regnar (something I now regret, as I could have spent far less on a brand new woofer from Layne Audio, or Simply Speakers) simply brought the speaker back to original operating condition. Replacing the mid bass drivers with Dayton Audio units did make a difference, and opened up male voices and lower register brass instruments. And now, the new super tweeters from Eminence have further improved the sound of the speakers.

But the best improvement wasn't the replacement of any of the drivers, but the installation of the "Hi-Fi Tuning Fuses" in each speaker - one "main" fuse, and the other one directly in line with the two tweeters. At $40 each, that may seem awfully high for just a fuse, but at $160 overall, the improvement in sound was more dramatic and noticeable than replaced drivers.

And those are my thoughts for the day!

Thanks for the update and review Ed, I always find your posts enlightening.

Jim

me too

glad you have the DQ's up and running at full speed Ed. it must have been torturous during the downtime.

Great, thoughtful post, as usual, Ed. Thank you.

I have little experience with piezzos, and always in cheapish pro-sound trapezoid speakers. I´ve never heard the DQ-10´s, which apparentlymake very good use of them.

My experience with supertweeters added to some Tannoy Prestige Series Speakers has been exactly as you described above. Actually, the benefits seem to extend further down the frequency range, with slight, but clearly noticeable improvements, on the upper midrange.

Jorge

Tanx for sharing.
Piezo tweeters have indeed a heavy signature in sound spectrum. I know piezo super tweeters quite well because we – the last band I’d played with - have a couple of them in our small P.A. system.
I never have think of using of a Piezo tweeter in a hi-fi speaker...

What kind of tweeter your DQ-10's have? The stock AD0162 or the KSN-1005?
A friend of mine made some interesting experiments with more gentle tweeters: the Philips AD0163 and the Dayton ND16FA-6 5/8" Neodymium Dome Tweeter and he’s quite content with both.

http://www.parts-express.com//pe/showdetl....tnumber=275-025

BTW, interesting opinion about the fuses...

I haven't changed the regular tweeter in the speakers, and have been thoroughly satisfied with the "stock" unit. My DQ-10's were purchased in 1977, so that might give you an idea which specific tweeters they are, but I always assumed that Dahlquist used the same tweeter throughout the entire production of the speakers.

The super tweeter replacement I purchased from Parts Express sells for about $25 each, and Regnar (the NY-based company that exclusively repairs Dahlquist speakers) sells "factory original" piezos for more. Sorry, but NO piezo is worth that much!

Insofar as the Hi-Fi Tuning Fuses go, I stumbled upon them over a year ago, and have long since been an avid supporter of using them. Even Stereophile lists them as a "recommended component," which says a lot too. I would have replaced the fuses in the various electronic components in my system with these fuses, but most such fuses are difficult to access.

As it turns out, I wired the new replacement tweeters out of phase with the rest of the system. Ordinarily, I can readily detect if an entire speaker system is out of phase with another, but given the little amount of information that comes out of these super tweeters, such was not the case here.

After extended listening, there were times I felt that the DQ-10's sounded somewhat harsh, and colored - certainly not what they used to sound like. Then, quite by accident, I stumbled across a schematic that proved that I had wired the new super tweeters incorrectly. Fixing this made all the difference, and I'm a bit surprised that there is that much of a difference simply by having just the super tweeter properly, or improperly, wired within the overall DQ-10 loudspeaker.

I guess it just illustrates how effectively each of the drivers works synergistically with the others, as there is a decided improvement in the openness of the upper end, and the "air" around many instruments and voices. Whether I do or don't hear anything above 12,000HZ may, or may not be relevant, but there's no question now that the Eminence drivers have made a very significant difference over the piezos in "original" DQ-10's, and I heartily recommend the upgrade. Just be sure to wire them correctly, and not as I did!

How about a few photos?

I am considering giving this a shot, perhaps, a bit down the road.

My digital camera is a relic, and posting photos here, or elsewhere, is something I have yet to master. Perhaps someday before I leave this earth...

Insofar as performing this upgrade yourself, I'd recommend first installing the Hi-Fi Tuning fuses, as I found that made a bigger difference. Your total cost should be around $160 for the four, and there's no removal of old drivers, and installations of new ones. Removing the piezos is a tricky matter also, as they're not just screwed into place, but cemented as well, so you have to be really careful not to ruin the masonite panel they're mounted on. Fuse replacements are far easier.

Monsieur Maidel's thread brings up a thought I've had for a long time: While I know some of these engineers got it about perfect the first time, it does NOT preclude the notion that their creations can be upgraded. Of course it's heresy, and cuts into the resale value. However, I plan to give my DQ-10s to my son, and I bet he listens to them, rather than selling them. Better is better, and there is also the element of upgrades in drivers since these speakers were introduced. The same dynamic exists with classic cars. But if you are hung up on keeping the old, inefficient AC compressor when you can replace it with something twice as effective and one quarter the weight, what is the point??? I knew a guy who sent his seat belts back to the FACTORY to be rewrapped in the plastic, for that perfectly original state. I want a car I can drive fast, and a stereo I can play loud and true.

That post makes a lot of sense. The question to be asked is, "If some of the newer - and better - drivers were available at the time the DQ-10 was developed, would Jon Dahlquist have used them?" I suspect the answer to that is, "Yes, as long as they weren't too expensive."

If anyone has had a conversation with the folks at Regnar, one of the first things readily apparent is that they feel the DQ-10 should never be altered or "up-graded" in any way, except for recapping the crossover, or rewiring the entire speaker. They are fiercely loyal to the original design, and rebuid drivers (at staggering costs) to original specs, and shun replacements of any kind. While they offer a replacement woofer for the DQ-10, their website clearly indicates it's only for those who no longer have the original, which they feel has never been topped. At least two websites offer "new & improved" woofers, though I haven't been able to find anyone who has used either of these woofers and commented on their performace.

I'm no speaker engineer, but have to admit the two "upgrades" I've performed - replacing the mid bass drivers and the piezos - have made a very real and audible improvement to the overall sound of the speaker, at relatively little expense, and at a fraction of the cost of a Regnar rebuild. I didn't bring my speakers back to "original specifications," but, at least in my own opinion, made them better.

My 1972 Camaro came with bias-ply tires which I ultimately replaced with radials. The difference in handling was remarkable. To a purist, I probably committed a crime by not keeping the car within "factory-original" specs, but then who is to say that "factory-original" can't be improved upon?

IMHO, everything can be upgraded or tweaked. Audio gear, cars, motorbikes or even the chair where i’m sitting now. Time changes, the same with technology and new materials. I’ve no problem in upgrading things for the better. If i have a set of those DQ-10’s i’m certain that i will do the same you’ve done with yours.
Enjoy.

Great to see a thread about the DQ-10. I have a matched set and I am using ADCOM separates. ADCOM might not be the BEST but the 555II fills them nicely. I want to ask Ed where he found the Hi-Fi Tuning Fuses. Do others agree that this is a worthwhile upgrade? Just added 2 Velodyne ULD-18s to fill the bottom end. Nice vintage setup.

There are a few more articles in the archives, there are a couple members that have a set.

elroy