Dahlquist DQ-10 repair/upgrade, If this works, I"ll be thrilled!

I've posted extensively (some might say "exhaustively") about my longtime enthusiasm for my Dahlquist DQ-10's. Even though I own a far costlier pair of B&W 802F Specials, my preference is the Dahlquists, and by a considerable margin.

Recently, I became aware of nasty distortion coming out of the mid-bass driver in one of the two speakers, and upon further investigation, realized that the piezo super-tweeter was dead. Other than having the woofers rebuilt by Regnar in NY a few years ago (for almost $300), I've done nothing to these speakers since I bought them in 1977. They aren't stock units, but what Dahlquist personnel called "show-models," that had unusual large, green block mylar capacitors in the crossover network, long before the yellow mylar caps became standard fare.

The mid bass driver is no longer manufactured, and if one chooses to send it in to Regnar, the cost for a rebuild is about the same as that for the standard woofers. I fully realize how important driver matching is in the DQ-10, but over $150 to rebuild a 5" woofer seems awfully high. So, I did an online search for Dahlquist replacement drivers and came across a Dayton RS 125S-8 5" woofer from Parts Express that, according to a poster on the site, is a far better driver than the original mid bass driver in the DQ-10. Whether that's so or not remains to be seen, but at a price of $27.22 each, I couldn't afford not to give them a try. Not to create an imabalance between the two speakers, I ordered two of these small woofers, and the entire order, including shipping came to $64.77 - less than half the price of a Regnar rebuild for just one of these drivers. I should have them in a few days, and after installing them, I'll report my findings here for all to read.

The Piezo super-tweeter has long been an audiophile's most hated tweeter, and the DQ-10 has long been criticized for using such a cheap driver. Jon Dahlquist's response was that, since the piezo doesn't begin until 12,00HZ, most people wouldn't hear much difference anyway at such high frequencies. Based on my long enjoyment of the DQ-10's, I have to agree with Jon.

Regnar sells replacement "original" DQ-10 supertweeters for about $26 each. While that doesn't seem like very much, what appears to be the exact same thing from Parts Express is only $1.44!! Naturally, I ordered two, again not to create an imbalance between my two speakers, and at such a ridiculously low price, I simply had to take the chance that they are indeed the same as that used in the DQ-10. They sure look like the same, but we'll see.

Years ago, on another website, I was bitterly criticized by other members for having spent so much on having the woofers rebuilt, as the woofer is basically the same thing used in the large Advent loudspeaker. I have to admit that the rebuild was infinitely superior to a very sloppy refoam job by Simply Speakers in Florida, but that cost only $80, and not over $300.

So, for well under $100, I now have not one rebuilt driver on its way to me, but four brand new ones. Will they do the job? Frankly, I all but can't wait to find out!

This post has been edited by emaidel on January 27, 2009 01:58 pm

do you think your fairly recent move had anything to do with losing sound in the 5 incher

Not at all. The speakers worked fine for about a year and a half, with the problem occurring only recently. Considering the speakers' age, I guess I should consider myself lucky that this is all that's wrong with them.

Well, the new drivers arrived, I installed them, and the results are wonderful. THere's no huge difference in sound, but there is a definite improvement, particularly in the sound of men's voices. A recent playing of the Boston Baroque's performance of "Messiah" on Telarc was simply glorious.

Unfortunately, the problem still exists, and after removing the speaker's grille, and very carefully listening to the speaker, I realized the problem isn't the upper bass driver at all, but the woofer. The "crackling" sound the woofer makes when played loudly, and with powerful bass material, seems to come from elsewhere at first listening, but is quite obviously coming from the woofer when the grille is off, and I've got my head almost inside the speaker!

I called Regnar to discuss this, and was informed that if I'm experiencing crackling sounds, then the woofer is blown. I paid Regnar $139.50 for each of the woofers to be rebuilt several years ago, but the warranty is only 1 year, and their cost to rebuild now has skyrocketed to $175.00. Just as an aside: the cost to rebuild the mid-bass driver isn't $150, but "only" $90.

Despite the fact that Regnar assured me in the past that there were subtle, but real, differences between the DQ-10 woofer and that from the Large Advent Loudspeaker, I'm going to give the Advent woofer a try. I've seen a few websites offering it for as little as $75 each, so I could purchase two of them and still save $5 over the cost of a single rebuild from Regnar.

I've sent emails to several websites asking about their Advent replacements, but haven't yet heard back. Still, if I buy only one, I"m not out that much cash if it really doesn't work as well as that in the DQ-10.

In the meantime, as long as I don't play my system too loudly, it sounds absolutely wonderful, and I'm delighted with the improvment the Dayton Audio drivers made. They're considerably better made than the original drivers in the DQ-10 with cast aluminum baskets instead of a stamped one, and with a far larger and heavier magnet.

This post has been edited by emaidel on February 06, 2009 06:28 am

you could also peruse the local used market, craigslist, thrifts, etc. for a Large Advents as they can usually be had in the $40 per pair range.

Ed, you might contact member GordonW and see what he can do, here is a link to his website. http://www.geocities.com/gordonwaters/

Jim

What about the old trick of pulling the woofers and rotating them 180 degrees to see of the surrounds are sagging and letting the voice coils rub?

Not at all. The speakers worked fine for about a year and a half, with the problem occurring only recently. Considering the speakers' age, I guess I should consider myself lucky that this is all that's wrong with them.

Have you ever thought to check aagain the crossovers components? Resistors and capacitors? I know they have great Mylar's caps, but sometimes even the best components have problems...or a solder joint...
Just a thought.

In my discssions with Joe, the service manager at Regnar, the possibility of faulty crossover components came up. Still, based on the specific problem I'm experiencing, Joe feels quite certain that it's a blown woofer, and not a bad crossover part. The only way to tell for sure is to switch the woofers from one speaker system to the other, and I may do that just to be sure before I buy a new one.

That would be unlikely, as the woofers were only recently (about 3 years ago) completely rebuilt by Regnar. Still, I guess it's worth a try.

Glad to hear your success with the midrange driver.

I worried about driver availability myself and ended up with a collection of upper-dahlquist drivers, from the dome tweets and mids to the cone mids and supertweets, but no spare woofers as of yet.

Still, I may give your driver swap a try myself.

And sorry to hear of the bum woofer.

Not the midrange, but the upper-bass driver.

Strangely, the problem is less obvious now than it was last time I listened to the system. Rather than have the woofer rebuilt (for $175 by Regnar), I'll most likely purchase new woofers from Simply Speakers in Florida at $129 each. They're woofers for the Large Advent loudspeaker, advertised as substitutes also for the woofers used in the DQ-10 and DQ-20, and as so many have substituted these for those in the DQ-10, with entirely satisfactory results, I think I'll go that route.

I know the work done by Regnar is exemplary, but the price tag for that work is getting a bit much.

I can't personally vouch for any likeness or difference regarding the woofers, but GordonW said he had the two opened up on the table and they are the same internally.

FWIW.

Gordon has said that before, but I, perhaps foolheartedly, chose to listen to the people at Regnar who insisted that there are differences. I guess they had to do, or say, something to justify their very high prices.

And, speaking of Regnar, as far as I know, the facility does nothing other than repair and/or rebuild Dahlquist loudspeakers of all model numbers. Dahlquist never sold the amount of speakers AR, KLH, Advent, or a host of others did, and it's hard to imagine there are enough people out there who own Dahlquist speakers who want them serviced by Regnar, and that these people exist in sufficient numbers to keep Regnar in business, making a profit, and paying its employees a decent wage. Kinda makes you wonder, no?

I would guess that they probably multitask a bunch, and service a bunch of different brands.

elroy