It is a standard driver and not specific to Duntech. Dynaudio stopped providing individual drivers to other manufacturers some time back and Duntech have been unable to purchase any spare drivers from them for a very long time now.
Dynaudio also have records of anything custom for specific manufacturers too.
Have you tried calling? I've always found Kiat to be very responsive and helpful.
Gap being gummed up from rear air filter remains means the driver voice coil is being prevented from freely moving within the gap, so your drivers are not working at all, and you have said the these units are bottoming out at certain drive level voltage. This is a contradiction. Then follows the remedy that the whole structure has to be disassembled, cleaned, and refoamed again, sent home for 137 bucks which incidentally equals the exact amount needed to buy a new Morel MW 266 unit at PE which is a reasonable replacement driver for Dynaudio 24W75 XL. Repair guy did not say what will happen to Thiele/Small parameters and whether bottoming out will seize to be a problem, after servicing.
Well, he did say that the bottoming out would stop and this sounds exactly like what he's seen many times with these drivers. My understanding from other Duntech and Dynaudio boards is that Millersound is probably the standard when it comes to these drivers.
You're saying they should not work at all?
You're saying they should not work at all?
Drivers are bottoming out because of couple of things. The drive voltage is too high, the physically available space for the voice coil travel until it hits back plate is 11.5mm, and the surround and spider are not stiff enough to prevent this from happening again.
Since first condition is unlikely to change, second will remain as is, then any mod to be applied is new surround, spider will remain original. This stiffer new surround will alter T/S parameters, changing the sound in some way.
I can tell you what happened to my drive units 24W75 after I had refoamed them.
Original foam, 15 years old after production:
Fs=31 Hz
Qms=3.51
Qes=1.09
Qts=0.83
Cms=1.19 mm/N
Vas=96.3 litres
SPL=88.17 dB/2.83V
New replacement foam:
Fs=41.08 Hz
Qms=4.81
Qes=1.59
Qts=1.19
Cms=0.66 mm/N
Vas=53.45 litres
SPL=87.65 dB/2.83V
New surround plays better, giving more articulate and dryer bass.
I am not saying what you should or shoudn't be doing.
Since first condition is unlikely to change, second will remain as is, then any mod to be applied is new surround, spider will remain original. This stiffer new surround will alter T/S parameters, changing the sound in some way.
I can tell you what happened to my drive units 24W75 after I had refoamed them.
Original foam, 15 years old after production:
Fs=31 Hz
Qms=3.51
Qes=1.09
Qts=0.83
Cms=1.19 mm/N
Vas=96.3 litres
SPL=88.17 dB/2.83V
New replacement foam:
Fs=41.08 Hz
Qms=4.81
Qes=1.59
Qts=1.19
Cms=0.66 mm/N
Vas=53.45 litres
SPL=87.65 dB/2.83V
New surround plays better, giving more articulate and dryer bass.
I am not saying what you should or shoudn't be doing.
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So you're saying you think the foam might be too "loose" or not stiff enough for the voltage? Apparently, this was the "exact" foam used in the original drivers.
To show that I'm feeding good power I've used two systems:
Mcintosh MA7900 integrated amp - pops at about 60% volume on the reader (not THAT loud)
PS Audio M700 monos (400wpc @ 8ohms) with Anthem STR preamp. Volume was at -20 yesterday when they popped during a heavy celine dion song.
That is NO WHERE near acceptable. I know I like music loud but this isn't that loud and I've blown the roof off before on the same music with other speakers (more and less efficient) and even older (Wilsons and Thiels). None "popped" at this output.
To show that I'm feeding good power I've used two systems:
Mcintosh MA7900 integrated amp - pops at about 60% volume on the reader (not THAT loud)
PS Audio M700 monos (400wpc @ 8ohms) with Anthem STR preamp. Volume was at -20 yesterday when they popped during a heavy celine dion song.
That is NO WHERE near acceptable. I know I like music loud but this isn't that loud and I've blown the roof off before on the same music with other speakers (more and less efficient) and even older (Wilsons and Thiels). None "popped" at this output.
Update... I got the drivers back from Millersound and they're still, um faulty, I guess. Millersound did a supurb job making them better but they're still short of my expectations, which I don't think are out of line at all. Millersound warned me this could be the case given the age of the drivers and he didn't want to totally redo the surrounds/spider because it would significantly alter the specs of the driver.
Anyway, I did contact Dynaudio and they can remake new woofers to brand new factory specs and they ENSURED me this would NOT be an issue with brand new drivers. However, they're $282 each. No return policy obviously.
Anyway, because of this, I'm kinda on the hunt for a pair of Dunlavy SC IV/a which I think would be a worthy competitor and the Scanspeak drivers shouldn't have this problem and are at least replaceable.
Anyway, I did contact Dynaudio and they can remake new woofers to brand new factory specs and they ENSURED me this would NOT be an issue with brand new drivers. However, they're $282 each. No return policy obviously.
Anyway, because of this, I'm kinda on the hunt for a pair of Dunlavy SC IV/a which I think would be a worthy competitor and the Scanspeak drivers shouldn't have this problem and are at least replaceable.
Sorry to hear the refoam job didn't solve the problem.
You are right that the dust cap is not removable. I refoamed a 24W100 and confirmed its molded into the cone. I found a YouTube video made by Dynaudio and for a brief moment, they showed the wires inserted thru the cone at the junction of the center cap. So I bought .35mm springy wires from McMaster-Carr. They have to be stiff or springy otherwise it would be almost impossible to insert them into the voice coil gap. It seems to have worked perfectly.
I also had pieces of the vent filter floating around and thought some had gotten into the voice coil gap. I shook, pushed the cone back and forth, and tap the frame on my workbench. Some of the stuff did come out but who knows if I got it all out. That seems to have worked because now the voice coil does not rub when before it did.
I recently built a new enclosure and played the speakers at moderately high levels using my 200w/ch amp in a sealed 50L enclosure. No unusual sounds or voice coil rubbing. Maybe I just got lucky.
You are right that the dust cap is not removable. I refoamed a 24W100 and confirmed its molded into the cone. I found a YouTube video made by Dynaudio and for a brief moment, they showed the wires inserted thru the cone at the junction of the center cap. So I bought .35mm springy wires from McMaster-Carr. They have to be stiff or springy otherwise it would be almost impossible to insert them into the voice coil gap. It seems to have worked perfectly.
I also had pieces of the vent filter floating around and thought some had gotten into the voice coil gap. I shook, pushed the cone back and forth, and tap the frame on my workbench. Some of the stuff did come out but who knows if I got it all out. That seems to have worked because now the voice coil does not rub when before it did.
I recently built a new enclosure and played the speakers at moderately high levels using my 200w/ch amp in a sealed 50L enclosure. No unusual sounds or voice coil rubbing. Maybe I just got lucky.
What do you mean by "short of expectations"?
My original woofers were repaired and sounded great. Previous owner was a family friend and I know he played them daily for 15+ years...
My original woofers were repaired and sounded great. Previous owner was a family friend and I know he played them daily for 15+ years...
I have a general series of music I like to run all my new speakers through when I get them, some of it has pretty deep and strong bass. I've never had a woofer "splat" "pop" "bottom out" etc on these tracks at this particular volume. Keep in mind it's loud but not stupid loud.
For instance, most Celtic Women tracks have a lot of good deep bass, I can't turn them past -20db on my preamp (Anthem STR)... Where as other speakers I can crank MUCH higher on dynamic tracks. Not these by far.
Now if I were turning these up to like -5db or 0db, sure I can see that but I don't abuse my speakers like that..
Also, I'm using plenty of power (PS Audio M700 mono blocks) so I'm FAR from clipping.
I do like to feel the power though so sure I turn it up a bit from time to time.
For instance, most Celtic Women tracks have a lot of good deep bass, I can't turn them past -20db on my preamp (Anthem STR)... Where as other speakers I can crank MUCH higher on dynamic tracks. Not these by far.
Now if I were turning these up to like -5db or 0db, sure I can see that but I don't abuse my speakers like that..
Also, I'm using plenty of power (PS Audio M700 mono blocks) so I'm FAR from clipping.
I do like to feel the power though so sure I turn it up a bit from time to time.
Which country do you live in? I may have a spare Morel MW266 drivers. I also have original recones for the Scanspeak 13M midrange driver, if that is what the speakers use.
Cheers,
Matt.
Cheers,
Matt.
Deep tight bass is one of the features of these speakers. Definitely sounds like you have a physical problem with the drivers. :-( I drive mine with ~500w per channel and the house shows more stress with windows rattling than the Duntechs.
If I was in your position, I'd get the rebuilt drivers from Dynaudio. The only thing I can fault my Crown Princes on is the very small sweet spot.
Wow ok that's encouraging. I don't care to bring the house down but I'd like some deep grunt sometimes. I can tell these speakers go very deep. But yeah, -20db is NOT that loud on my preamp for these things to be "splatting" on deep bass notes.
Only thing that concerns me is my repairman was 99% positive this would fix them and I'm not sure that's the case anymore. New drivers will run about $1200.
Only thing that concerns me is my repairman was 99% positive this would fix them and I'm not sure that's the case anymore. New drivers will run about $1200.
I mean, I don't expect these to slam like my Tektons or Klipsches, but I do expect them not to "fall apart" or get "floppy" in the lower bass when stressed just a little (again, not cranking it to 10). What's crazy is I think they sound superb up until that point.
To reiterate, when I get new speakers I like to put them through a quick stress test. The only speaker I've bottomed out was a Wilson Watt Puppy 5.1 but it had a faulty woofer.
I've been told that I can't expect a 30 year old speaker to handle this amount of power but I've had plenty of 30+ year old speakers that can take this very reasonable stress test in stride.
To reiterate, when I get new speakers I like to put them through a quick stress test. The only speaker I've bottomed out was a Wilson Watt Puppy 5.1 but it had a faulty woofer.
I've been told that I can't expect a 30 year old speaker to handle this amount of power but I've had plenty of 30+ year old speakers that can take this very reasonable stress test in stride.