I just grabbed a couple of Dahlquist DQ 10s for 200 Canadian is there a thread on this forum that can assist me with the subject of rebuilding them and potentially modifying the crossovers and possibly adding a passive rad to the back of the base cabinet I just registered on this site today so I’m not familiar with it my apologies for posting my question in the wrong section if I have done so
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I think Jon did a pretty decent job of system engineering with these so I’d take a very cautious approach, starting obviously with replacing the surrounds on the woofers. The most adventurous I got with mine was to mirror image the mounting of the drivers - actual quite a fussy bit of work - and even though the material of those 4 “open baffles” was quite thin, to chamfer their edges. At well over 40yrs of age, it’s also likely that the ELCOs may benefit from replacement, and there’s certainly not much to lose except hours of research, analysis paralysis and probably several hundred dollars by rebuilding the XOs. I never did with mine, but maybe start here:
https://www.google.ca/search?q=Dahl...tic.&ie=UTF-8&oe=UTF-8&hl=en-ca&client=safari
If I’m not mistaken, the pre-internet hi-fi rumour mill postulated his intent was to voice the bandwidth, tonality and dispersion properties of the Quad ESL57. Rather than attempt to “improve” the bass performance by adding PR, I’d leave the sealed enclosure as is, and augment them with separate sub(s). I added one of his original DQ 1W and passive XO, and it worked very well indeed, but the total riggings was rather oversized for my then very small space.
Just my
https://www.google.ca/search?q=Dahl...tic.&ie=UTF-8&oe=UTF-8&hl=en-ca&client=safari
If I’m not mistaken, the pre-internet hi-fi rumour mill postulated his intent was to voice the bandwidth, tonality and dispersion properties of the Quad ESL57. Rather than attempt to “improve” the bass performance by adding PR, I’d leave the sealed enclosure as is, and augment them with separate sub(s). I added one of his original DQ 1W and passive XO, and it worked very well indeed, but the total riggings was rather oversized for my then very small space.
Just my
Is there a problem you have identified to fix, or are you just assuming this is something that should be done? Perhaps you could get an equaliser and tune/voice the speaker that way...
Join this group: https://groups.io/g/DahlquistSpeakers
A lot of knowledgable DQ10 people there. I have worked on a few pairs, did the mirror image on one. I wouldn't do much more than consider the mirror image project, redoing a few parts of the crossover and consider some of the tweeter replacement options. Redoing surrounds is easy to do as well. I've not had any issues with the dome mids but if those are in bad shape you are probably screwed. The mid bass drivers can have stiff surrounds, there are a variety of opinions on how to approach that.
A lot of knowledgable DQ10 people there. I have worked on a few pairs, did the mirror image on one. I wouldn't do much more than consider the mirror image project, redoing a few parts of the crossover and consider some of the tweeter replacement options. Redoing surrounds is easy to do as well. I've not had any issues with the dome mids but if those are in bad shape you are probably screwed. The mid bass drivers can have stiff surrounds, there are a variety of opinions on how to approach that.
There is a long DQ10 thread. The bottom is best left sealed, making it reflex is a bad idea.
Mirror image them. You need to get a bit creative. Puzzlekoat/ModPodge the paper cones. Ductseal the basket. Use better wire. Maybe some bracing in the woofer enclosure.
You ar elooking for an advent 10” set of surrounds.
I’ll let others weigh in on XO.
dave
Mirror image them. You need to get a bit creative. Puzzlekoat/ModPodge the paper cones. Ductseal the basket. Use better wire. Maybe some bracing in the woofer enclosure.
You ar elooking for an advent 10” set of surrounds.
I’ll let others weigh in on XO.
dave
Crossover was optimized to provide best possible square wave response. I would leave it as is.
👍 I think Jon had a pretty good handle on that.
As best as I can recall, there was a pesky doping of the XO board with a layer of paraffin wax that made relocating the board and routing of wires a messy pain in the a$$ when mirror imaging them.
Provided the voice coils and lower spiders are intact, resurrecting the woofers should be too much of a problem, but should any of the other drivers aside from the piezo super tweeter need replacing, things would get tricky.
It was long before fora such as these that I regrettably had to move on from my pair of DQ10, so I never had reason to chase the tweakers’ ethos, which is often a combination of “anything commercial product affordable on my budget must have been compromised”, and “I read in Absolute Sound / on the internet that …….., so it must be true that ……”
As best as I can recall, there was a pesky doping of the XO board with a layer of paraffin wax that made relocating the board and routing of wires a messy pain in the a$$ when mirror imaging them.
Provided the voice coils and lower spiders are intact, resurrecting the woofers should be too much of a problem, but should any of the other drivers aside from the piezo super tweeter need replacing, things would get tricky.
It was long before fora such as these that I regrettably had to move on from my pair of DQ10, so I never had reason to chase the tweakers’ ethos, which is often a combination of “anything commercial product affordable on my budget must have been compromised”, and “I read in Absolute Sound / on the internet that …….., so it must be true that ……”
Do not vent the woofer! You could break up standing waves inside the box however, which I did. With a 150+ wpc amp and set up right with the room boundaries, you get an honest 40 Hz. I had the xover they made and tried a series of woofers including my own builds, but they never sounded right, better with stuff like ProAc Tabletter, KEF 101, Rogers LS35A.
With all due respect to Jon Dahlquist, the piezo is a piece of junk, unless you want to restore it to mint, consider getting rid of it in favor of a ribbon or AMT, and further consider making it a 4 way by getting rid of the tweet and super tweet. You have to likely make an adjustment on the resistor value.
the mirror image is a good idea, but does take time.
Every cap has to be replace, preferably with film, and the caps for the mid/tweet and above ought to be high quality and as they get smaller the cost shouldn't kill you and use a .01 uf in series with the cap for the highest frequency driver - helps get rid of cruft.
The mid/woof voice coil goes out of alignment - 3 of the 8 drivers I was familiar with had this problem. They say the mid/tweet dome has this issue too, but I hadn't seen it. Those 2 types of driver are very hard to find or replace with similar types, so good luck on that.
The resistors might be going too, at least check them for value and if one bad, or too far out of spec, consider getting 1 or 2% replacements for the pair, not just the bad one.
I spent hundreds of hours with mine in the 1987-1992 time frame - it was fun, but got married and they didn't look so hot in the living room....
With all due respect to Jon Dahlquist, the piezo is a piece of junk, unless you want to restore it to mint, consider getting rid of it in favor of a ribbon or AMT, and further consider making it a 4 way by getting rid of the tweet and super tweet. You have to likely make an adjustment on the resistor value.
the mirror image is a good idea, but does take time.
Every cap has to be replace, preferably with film, and the caps for the mid/tweet and above ought to be high quality and as they get smaller the cost shouldn't kill you and use a .01 uf in series with the cap for the highest frequency driver - helps get rid of cruft.
The mid/woof voice coil goes out of alignment - 3 of the 8 drivers I was familiar with had this problem. They say the mid/tweet dome has this issue too, but I hadn't seen it. Those 2 types of driver are very hard to find or replace with similar types, so good luck on that.
The resistors might be going too, at least check them for value and if one bad, or too far out of spec, consider getting 1 or 2% replacements for the pair, not just the bad one.
I spent hundreds of hours with mine in the 1987-1992 time frame - it was fun, but got married and they didn't look so hot in the living room....
Dahlquist was at Harry Pearsons home (TAS Editor) a number of times in 1972-74, revising the DQ-10. He used the Marantz 500, Citation 11, and ARC D76 amps to design it on. ALso the ADC XLM, ARC SP3. The staff of TAS also got involved in feedback - even after the initial release, past when the change from the CTS woofer was made.I think Jon did a pretty decent job of system engineering with these so I’d take a very cautious approach, starting obviously with replacing the surrounds on the woofers. The most adventurous I got with mine was to mirror image the mounting of the drivers - actual quite a fussy bit of work - and even though the material of those 4 “open baffles” was quite thin, to chamfer their edges. At well over 40yrs of age, it’s also likely that the ELCOs may benefit from replacement, and there’s certainly not much to lose except hours of research, analysis paralysis and probably several hundred dollars by rebuilding the XOs. I never did with mine, but maybe start here:
https://www.google.ca/search?q=Dahl...tic.&ie=UTF-8&oe=UTF-8&hl=en-ca&client=safari
If I’m not mistaken, the pre-internet hi-fi rumour mill postulated his intent was to voice the bandwidth, tonality and dispersion properties of the Quad ESL57. Rather than attempt to “improve” the bass performance by adding PR, I’d leave the sealed enclosure as is, and augment them with separate sub(s). I added one of his original DQ 1W and passive XO, and it worked very well indeed, but the total riggings was rather oversized for my then very small space.
Just my
HP intimates in the watershed review in Spring 1974 that Dahlquist was trying to mimic the Quad ESL - the shape and the metal cage certainly were visual cues. The imaging and precise sound were also a paean to the Quad.
My father had a pair of Quads for 7 years, and I had the DQ-10 for 4 years. Listening to the Quad ESL 57 its clear that its more precise and pure then the DQ-10 with less lower bass, and top treble, and less ability to play loud. Take a look at the CSD plots and IM distortion of the Quad - not sure that any speaker made today is better than a 66 year old design in those ways. But the Quad is very short on dynamics - which the DQ-10 bettered, but not by that much.
Agreed on the woofer - do not vent the cabinet - if you must, you must model it carefully as a random hole and tube is going to get goodness knows what results.
Actually I misread the passage I quoted. They didn't like the Citation 11, but used the ARC SP3 almost exclusively as a preamp. Amazing how much the electronics quality and selection took off around mid decade of the 1970's. The great tuner wars for one.
Yes, and it ended up in its final rev was I believe SP-3a-1. I had the SP-3A-1 on loan for a month, then had an SP11 which was excellent, and then the 15 for the MC phono and polarity switching. Not too many folks remember the old days.
I've looked at these various DIY designs - pensil, FHXL - but they all seem to be run by small watt tubes. I've got a Ragnarok 1 which has a sliding bias Class A to 4 wpc, and in Gain 1 doesn't seem to have any pre-amp gain stage - its clean and dips at the extremes in Gain 1. Gain 2 is for my planar headphones and my speakers unless I want to rock, Had to downsize from the old days. The reviews are pretty rhapsodic. My favorite speaker I owned was the Verity Parsifal III, tell me its going to get into that neighborhood. Timbre, transparency, soundstage with depth, and limited/controlled ringing in above 3k.
You seem to be a terminally busy guy - thanks for reading.
I've looked at these various DIY designs - pensil, FHXL - but they all seem to be run by small watt tubes. I've got a Ragnarok 1 which has a sliding bias Class A to 4 wpc, and in Gain 1 doesn't seem to have any pre-amp gain stage - its clean and dips at the extremes in Gain 1. Gain 2 is for my planar headphones and my speakers unless I want to rock, Had to downsize from the old days. The reviews are pretty rhapsodic. My favorite speaker I owned was the Verity Parsifal III, tell me its going to get into that neighborhood. Timbre, transparency, soundstage with depth, and limited/controlled ringing in above 3k.
You seem to be a terminally busy guy - thanks for reading.
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Thanks for all the input. I travelled quite a ways to a speaker repair shop and ended up speaking with an older gentleman with 40yrs in the business of speaker building. I told him I wasn't limited in my budget and I had time to refurbish the DQ10s I also have a hobby shop and am quite handy. What he ended up selling me was new foam surrounds for the Advent woofers and capacitors they were GIGANTIC OMG I had to build separate crossover boards, the guy explained to me the most critical cap to replace will be replaced by the giant caps 16UA he had smaller cheaper caps for this but told me there is no more critical upgrade I can make in these speakers than replacing the 16UA cap. I have since installed the foam surrounds, simple job. He spent a fair bit of time with me discussing crossover mods . He pointed out that since I wasn't limited in budget and he sells parts he could easily have my bill at $500 in no time at which point he chuckled. What he ended up doing was going into quite a bit of detail with respect to what parts were on my crossovers, what would give me best bang for the buck, and what would only provide me with diminishing returns for my money as well as what I should leave well enough alone. At this point he has been helping me for about 45 min no charge. I am hopeful that I will be happy with what I got for under $200 Can. I don't know anything about speakers or crossovers so if something in my mods raises a flag please let me know. I am going to consider all the mods already mentioned here by members ( thank you ) including mirror imaging ( worth the effort ? ) cabinet dampening etc also do I simply remove the high frequency fuse and solder the leads together? And the treble control dial is under ten bucks so regardless of the current ones functioning well why not drop new ones in while the woofers are out? The base cabinet was filled with what looks like home fibreglass insulation is there something better? I wasn't comfortable trying to get all these answers from the guy at the speaker shop as he had been so generous with his time so here I am.
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There are two paper cones the bass driver and the 4" mid bass driver correct? I have never heard of these products, coat the cones front and back? how much do you apply? When you say basket you mean the frame of the woofer? Is plumbers putty sufficient? Thanks for now.
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I just began the mirror image work and after desoldering and removal of the baffles I see the Piezo tweeter is epoxied directly to the Bakelite backer board, other than dropping it into a wood chipper anyone have ideas as to how to separate these items?
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I missed this thread earlier.
As others pointed out for good reason, don't put a passive radiator in the cabinets. The box is actually a touch too small for that woofer and you won't be able to properly convert it to a reflex box. Dahlquist later on sold an add-on subwoofer, the DQ-1W that used the SEAS 33F-WK (great driver for the time), to address the bass deficiencies. That'd be the way to go if the desire is to stay period correct.
Don't coat the cones with anything. That's one of those bad tweaks that audiophiles fall for thinking it must do something good because it changes how it looks. It's a good way to make the breakup behavior unpredictable and ruin a driver that's operating in the midrange. They already have cone treatments originally. So, no need to mess that up. Do check the Philips driver, the 5" unit, for surround issues. The rubber hardens with time and cracks, both of which can throw it way out of spec. There are foam resurround kits available for it (it's an odd size) that I can point you to if you need them. You don't want to mess with the drivers in the DQ-10. These drivers were intentionally selected not because they were the best at the time, there were certainly better drivers out there, but because they integrated the best to offer unparalleled coherence for the 1970s. Change how the cones behave, change their tonal character with coatings and whatnot and you'll ruin everything that made these speakers exceptionally good for the time.
Your crossovers are from an older set with all electrolytic capacitors other than on the supertweeter. They should all be replaced by this point. The important caps to address are, yes, the 16uF, but also the 80uF. Either of those going bad will make half the speaker go silent. That said, the 6.5uF, two 6.0uFs (two of the older 6.5uFs were converted to 6.0uF in later revisions, not sure if yours are late enough to reflect that) and the 8.5uF (earlier examples were 8.0uF and 8.2uF, 8.5uF was the last revision) cap. None of the originals should be left in place as they will be either bad, off-value or high ESR and leakage at this point. The Matsushitas (caps with triangle emblem) may still be passing enough of a signal to sort of work still, but those black caps with red ends are guaranteed shot by this point.
Leave the fiberglass in the box. It needs it to damp the woofer and fiberglass remains one of the best materials for that in the bass frequencies. It's just obnoxiously itchy.
Be careful with that piezo horn. The masonite baffle board has a nasty habit of snapping and it becomes a pain to replace short of buying one from a parted out DQ-10 off of eBay. Try a knife and just work your way about it, a little bit at a time, as best you can.
As others pointed out for good reason, don't put a passive radiator in the cabinets. The box is actually a touch too small for that woofer and you won't be able to properly convert it to a reflex box. Dahlquist later on sold an add-on subwoofer, the DQ-1W that used the SEAS 33F-WK (great driver for the time), to address the bass deficiencies. That'd be the way to go if the desire is to stay period correct.
Don't coat the cones with anything. That's one of those bad tweaks that audiophiles fall for thinking it must do something good because it changes how it looks. It's a good way to make the breakup behavior unpredictable and ruin a driver that's operating in the midrange. They already have cone treatments originally. So, no need to mess that up. Do check the Philips driver, the 5" unit, for surround issues. The rubber hardens with time and cracks, both of which can throw it way out of spec. There are foam resurround kits available for it (it's an odd size) that I can point you to if you need them. You don't want to mess with the drivers in the DQ-10. These drivers were intentionally selected not because they were the best at the time, there were certainly better drivers out there, but because they integrated the best to offer unparalleled coherence for the 1970s. Change how the cones behave, change their tonal character with coatings and whatnot and you'll ruin everything that made these speakers exceptionally good for the time.
Your crossovers are from an older set with all electrolytic capacitors other than on the supertweeter. They should all be replaced by this point. The important caps to address are, yes, the 16uF, but also the 80uF. Either of those going bad will make half the speaker go silent. That said, the 6.5uF, two 6.0uFs (two of the older 6.5uFs were converted to 6.0uF in later revisions, not sure if yours are late enough to reflect that) and the 8.5uF (earlier examples were 8.0uF and 8.2uF, 8.5uF was the last revision) cap. None of the originals should be left in place as they will be either bad, off-value or high ESR and leakage at this point. The Matsushitas (caps with triangle emblem) may still be passing enough of a signal to sort of work still, but those black caps with red ends are guaranteed shot by this point.
Leave the fiberglass in the box. It needs it to damp the woofer and fiberglass remains one of the best materials for that in the bass frequencies. It's just obnoxiously itchy.
Be careful with that piezo horn. The masonite baffle board has a nasty habit of snapping and it becomes a pain to replace short of buying one from a parted out DQ-10 off of eBay. Try a knife and just work your way about it, a little bit at a time, as best you can.
Yes, the woofer has been discussed in detail, the mid is a Philips paper cone.
https://www.t-linespeakers.org/design/tweeks.html
It is best used thinned a bit, how much depends on what range the driver covers. With a FR one uses as little as possible just on the front. A woofer is different. It will not be impacted as much in the HF (out of band), more can be applied, and both sides, but i would just do 1 or 2 coats of thinned ModPodge so as not to change the T/S significantly but being a sealed box not at all dire.
It is a PVA formulation that dries with more flexibility and used for decoupage. Many different brands.
dave