Do Quads wear out "all at once"?

Dogberry

Member
Aug 24, 2022
17
9
5
64
I have lived with Quad electrostatics for 20 years. Firstly the 989s which was not a happy experience since they failed every other time they were switched on and had to be shipped across the country for repair. Eventually the dealer gave me a good price on some 2905s to make me go away. It worked - for 15 years!
But earlier this year, one speaker started to arc, despite never being played loud and with only 40W amps. I was lucky to find a guy who could repair it just three hours away, and he replaced the failed panel and at the same time upgraded all the caps in my tube amps. Now, a different panel in the same speaker is going the same way. He tells me the glue gets brittle with age and leads to the Mylar film flapping in the breeze until it touches the stator and a new hole is born. So I'm looking at having another panel replaced, but what about the other ten panels that are left? Probably about 6kCDN to do them, and I see used 2905s for sale for less than that. I do love them, but I'm making do while they are out of service with an old set of DCM TimeFrame TF-700s, which are not bad (and to be honest, liked a lot better by my wife who keeps making comments about the monoliths from 2001).
Are there any long term Quad owners who can speak to this - is all the glue likely to be failing with age and brittleness by now?

Chris
 

AMR / iFi audio

Industry Expert
Aug 21, 2019
2,117
920
215
42
UK
ifi-audio.com
I have lived with Quad electrostatics for 20 years. Firstly the 989s which was not a happy experience since they failed every other time they were switched on and had to be shipped across the country for repair. Eventually the dealer gave me a good price on some 2905s to make me go away. It worked - for 15 years!
But earlier this year, one speaker started to arc, despite never being played loud and with only 40W amps. I was lucky to find a guy who could repair it just three hours away, and he replaced the failed panel and at the same time upgraded all the caps in my tube amps. Now, a different panel in the same speaker is going the same way. He tells me the glue gets brittle with age and leads to the Mylar film flapping in the breeze until it touches the stator and a new hole is born. So I'm looking at having another panel replaced, but what about the other ten panels that are left? Probably about 6kCDN to do them, and I see used 2905s for sale for less than that. I do love them, but I'm making do while they are out of service with an old set of DCM TimeFrame TF-700s, which are not bad (and to be honest, liked a lot better by my wife who keeps making comments about the monoliths from 2001).
Are there any long term Quad owners who can speak to this - is all the glue likely to be failing with age and brittleness by now?

Chris
Not a Quad user, but my friends are. The glue will start to fail with time. It is a lottery when it happens. It's hard to say how it will go in your case, but usually, they wear out pretty similarly. Maybe you can ask Quad if they have a better glue that you can get. That way, you would redo them but have the trust for many years to come?
 

Dogberry

Member
Aug 24, 2022
17
9
5
64
My repair guy has looked at re-gluing, and says he doesn't feel it is likely to work well. I am as torn as a Mylar film about this, as while I know how clear they sound, I also get very comfortable, very quickly, with my 30-year old DCM TimeFrames. What a shame that brand disappeared!
 

AMR / iFi audio

Industry Expert
Aug 21, 2019
2,117
920
215
42
UK
ifi-audio.com
My repair guy has looked at re-gluing, and says he doesn't feel it is likely to work well. I am as torn as a Mylar film about this, as while I know how clear they sound, I also get very comfortable, very quickly, with my 30-year old DCM TimeFrames. What a shame that brand disappeared!
I understand it's hard to relax when you are not trusting your gear. I experience the same feeling if something is acting out in my setup.
I've looked up the DCM TimeFrames, and you can get them for very reasonable money. Do you know why they have disappeared?
 

Dogberry

Member
Aug 24, 2022
17
9
5
64
DCM had great success with their original TimeWindow speakers, and the TimeFrames were smaller and cheaper. They came in several sizes, and had a reputation for speed and responsiveness that made them sound a bit like electrostatics, or so it was claimed. That's why I bought them, but they don't really sound like Quads! Nice design, three drivers set in a flat surface angled back slightly, with a transmission line behind the largest terminating at a port lower down on that surface. I guess they disappeared because fashions apply to hi-fi just as much as anything else, and at the time speaker design was wandering into boomy Cerwin-Vega territory. They certainly didn't sound like that. Mine got regularly attacked by a cat who felt they were there to be a scratching post, so I'd better get around to finishing his job on the cloth socks, and then either re-covering them or maybe I'll just paint the MDF and leave them uncovered. No cats or small fingers to do any damage now. I've attached a pdf of the leaflet that came with them, which might be of interest.
 

Attachments

  • DCM TF700-specs.pdf
    812.1 KB · Views: 7

AMR / iFi audio

Industry Expert
Aug 21, 2019
2,117
920
215
42
UK
ifi-audio.com
DCM had great success with their original TimeWindow speakers, and the TimeFrames were smaller and cheaper. They came in several sizes, and had a reputation for speed and responsiveness that made them sound a bit like electrostatics, or so it was claimed. That's why I bought them, but they don't really sound like Quads! Nice design, three drivers set in a flat surface angled back slightly, with a transmission line behind the largest terminating at a port lower down on that surface. I guess they disappeared because fashions apply to hi-fi just as much as anything else, and at the time speaker design was wandering into boomy Cerwin-Vega territory. They certainly didn't sound like that. Mine got regularly attacked by a cat who felt they were there to be a scratching post, so I'd better get around to finishing his job on the cloth socks, and then either re-covering them or maybe I'll just paint the MDF and leave them uncovered. No cats or small fingers to do any damage now. I've attached a pdf of the leaflet that came with them, which might be of interest.
Excellent impulse responses. They are well-tuned, for sure! How would you describe their sound signature?

I remember the day my cat pierced my speaker's suspension and diaphragm. Just as she did it, and I shouted at her to get off she disappeared for a week. She immediately knew what was up. I honestly didn't even know where she was hiding (I guess that was the reason for hiding) ;)
 

Dogberry

Member
Aug 24, 2022
17
9
5
64
They have very little personality - if you go from the Quads to them everything seems warmer, more rounded but less detailed. Listen to them for a few hours and you start thinking how clear they are! Auditory memory is fickle. If I have to give up on the Quads, I know that I will have an intellectual understanding that I'm missing something, but I also appreciate I won't be able to hear the difference without a side by side comparison.
 

AMR / iFi audio

Industry Expert
Aug 21, 2019
2,117
920
215
42
UK
ifi-audio.com
They have very little personality - if you go from the Quads to them everything seems warmer, more rounded but less detailed. Listen to them for a few hours and you start thinking how clear they are! Auditory memory is fickle. If I have to give up on the Quads, I know that I will have an intellectual understanding that I'm missing something, but I also appreciate I won't be able to hear the difference without a side by side comparison.
In my experience, that description is a massive compliment for the cheaper gear. You know it's not as good, but you don't feel the need to go back to the more expensive option.
It's really good to have two way to play the music, like a flavour of the month: today I want this one :)
 

Dogberry

Member
Aug 24, 2022
17
9
5
64
I spent three hours today looking over the shoulder of a skillful repairman as he dissected a Quad 2905. It takes about 20 minutes to get the speaker stripped down to the point where you can see and test the panels. There are six separate panels, two bass at the bottom, two mid/high range in the middle, and two more bass panels at the top. For those who don't know, each panel is a sandwich, with a plastic grid of 2cm squares on the outside front and back. Inside this is a copper panel perforated by a grid of small circular holes, resting against a phenolic board like a PCB (again, front and rear). Between the phenolic boards is a Mylar membrane, glued at the edge to the rear plastic grid's outer edge. There is a 2-3mm gap between the Mylar and the PCB in front of, and behind it. The Mylar has a graphite coating all over except for the very edges. High voltage is fed into the copper stator on each side of the Mylar, and the graphite responds by by being drawn to or repelled from the stators. The stators are solid single pieces of copper for the bass panels as low sounds are non-directional. The mid range/treble panels have the classic Quad arrangements of concentric circles of the copper mesh, each part circle connected separately through delay lines so that the two treble panels act like one large concave/convex panel, simulating a point source.

All the delay lines must be unsoldered to remove panels, and reconnected afterwards.

My faulty panel, this time, was the lowest bass panel, and the phenolic board at the front of the sandwich with the copper stator on it was detached from the plastic frame at one side. Originally, it was glued in place. Careful probing with an insulated tool makes the loose part of the stator arc noisily as it is pushed towards the Mylar. So that panel was removed and replaced with a new one ordered from Mo-Fi some weeks ago.

However, the four original panels in that speaker (two now being replaced with new ones) all have the same problem developing, and all on the same side of the front face. They have come loose from the frame, but are not yet loose enough to cause arcing. Comparing old and new panels one can see some differences. The glue on the originals is slopped around a bit, but is extremely sparse or absent where the phenolic board is loose. The new panels have a visible bead of glue connecting the stator to the plastic grid.

So we scratched our heads for a bit, and discussed various glues. We don't want water based glue, and we don't want it to penetrate through the phenolic board. We decided to place a blob of industrial hot glue at each cross of the grid, and then used a dental pick to pull the copper stator back up against the glue as it set. We used one of the old panels as a test first to ensure the Mylar would not be hurt by the heat of the glue - it wasn't. Then I remembered the roasting bags for poultry, which I think are made of Mylar, so it should resist heat OK. At the end, all the stators on the front are well-affixed to their frame. None of the stators on the back of the panels were loose at all. Looks like a poor manufacturing process led to insufficient glue, and I'm guessing Quad became aware of it since the new panels have lots more glue on them. Then the speaker was reassembled and we set off home.
It works just fine now. So what was the point of the hot glue? As the end of the stator starts to flap in the breeze it gradually detaches for more of its length, and at some point it can move enough to touch the Mylar and it arcs. After a short (pun intended) while there is a hole burned right through the Mylar. By fixing the stators firmly with glue I hope we have reset the clock on those panels, or at least at that end of them, as the other end had no looseness, and nor did the rear stator as I said above. Time will tell.

As for doing it myself if needed, I think I can. There are airtight dust screens that look like Saran wrap on the front and rear of the speaker, to keep dust out (!) - because an accumulation of dust would increase the risk of arcing. The PCB with the delay coils and circuitry on it is coated in wax, probably beeswax, as it is outside of the sealed dust screens, and again any dust gathering between the terminals that the delay lines are soldered onto will encourage the terminals to arc. So after re-soldering the delay lines we dripped a beeswax candle onto the terminals. Not as pretty as the factory finish, but it should work.

Now the other speaker hasn't had a problem at all, so far. I could take it apart now and go at it with the glue gun if needed, but I think I'll wait until it starts to cause trouble, replace the panel that goes, and apply glue to all the others if showing signs of loosening. Fingers crossed, it won't happen...
 
  • Like
Reactions: dan31

AMR / iFi audio

Industry Expert
Aug 21, 2019
2,117
920
215
42
UK
ifi-audio.com
I spent three hours today looking over the shoulder of a skillful repairman as he dissected a Quad 2905. It takes about 20 minutes to get the speaker stripped down to the point where you can see and test the panels. There are six separate panels, two bass at the bottom, two mid/high range in the middle, and two more bass panels at the top. For those who don't know, each panel is a sandwich, with a plastic grid of 2cm squares on the outside front and back. Inside this is a copper panel perforated by a grid of small circular holes, resting against a phenolic board like a PCB (again, front and rear). Between the phenolic boards is a Mylar membrane, glued at the edge to the rear plastic grid's outer edge. There is a 2-3mm gap between the Mylar and the PCB in front of, and behind it. The Mylar has a graphite coating all over except for the very edges. High voltage is fed into the copper stator on each side of the Mylar, and the graphite responds by by being drawn to or repelled from the stators. The stators are solid single pieces of copper for the bass panels as low sounds are non-directional. The mid range/treble panels have the classic Quad arrangements of concentric circles of the copper mesh, each part circle connected separately through delay lines so that the two treble panels act like one large concave/convex panel, simulating a point source.

All the delay lines must be unsoldered to remove panels, and reconnected afterwards.

My faulty panel, this time, was the lowest bass panel, and the phenolic board at the front of the sandwich with the copper stator on it was detached from the plastic frame at one side. Originally, it was glued in place. Careful probing with an insulated tool makes the loose part of the stator arc noisily as it is pushed towards the Mylar. So that panel was removed and replaced with a new one ordered from Mo-Fi some weeks ago.

However, the four original panels in that speaker (two now being replaced with new ones) all have the same problem developing, and all on the same side of the front face. They have come loose from the frame, but are not yet loose enough to cause arcing. Comparing old and new panels one can see some differences. The glue on the originals is slopped around a bit, but is extremely sparse or absent where the phenolic board is loose. The new panels have a visible bead of glue connecting the stator to the plastic grid.

So we scratched our heads for a bit, and discussed various glues. We don't want water based glue, and we don't want it to penetrate through the phenolic board. We decided to place a blob of industrial hot glue at each cross of the grid, and then used a dental pick to pull the copper stator back up against the glue as it set. We used one of the old panels as a test first to ensure the Mylar would not be hurt by the heat of the glue - it wasn't. Then I remembered the roasting bags for poultry, which I think are made of Mylar, so it should resist heat OK. At the end, all the stators on the front are well-affixed to their frame. None of the stators on the back of the panels were loose at all. Looks like a poor manufacturing process led to insufficient glue, and I'm guessing Quad became aware of it since the new panels have lots more glue on them. Then the speaker was reassembled and we set off home.
It works just fine now. So what was the point of the hot glue? As the end of the stator starts to flap in the breeze it gradually detaches for more of its length, and at some point it can move enough to touch the Mylar and it arcs. After a short (pun intended) while there is a hole burned right through the Mylar. By fixing the stators firmly with glue I hope we have reset the clock on those panels, or at least at that end of them, as the other end had no looseness, and nor did the rear stator as I said above. Time will tell.

As for doing it myself if needed, I think I can. There are airtight dust screens that look like Saran wrap on the front and rear of the speaker, to keep dust out (!) - because an accumulation of dust would increase the risk of arcing. The PCB with the delay coils and circuitry on it is coated in wax, probably beeswax, as it is outside of the sealed dust screens, and again any dust gathering between the terminals that the delay lines are soldered onto will encourage the terminals to arc. So after re-soldering the delay lines we dripped a beeswax candle onto the terminals. Not as pretty as the factory finish, but it should work.

Now the other speaker hasn't had a problem at all, so far. I could take it apart now and go at it with the glue gun if needed, but I think I'll wait until it starts to cause trouble, replace the panel that goes, and apply glue to all the others if showing signs of loosening. Fingers crossed, it won't happen...
An excellent post. It was very interesting to read! Thank you. We hope that you won't have to go through all of that again!
 

About us

  • What’s Best Forum is THE forum for high end audio, product reviews, advice and sharing experiences on the best of everything else. This is THE place where audiophiles and audio companies discuss vintage, contemporary and new audio products, music servers, music streamers, computer audio, digital-to-analog converters, turntables, phono stages, cartridges, reel-to-reel tape machines, speakers, headphones and tube and solid-state amplification. Founded in 2010 What’s Best Forum invites intelligent and courteous people of all interests and backgrounds to describe and discuss the best of everything. From beginners to life-long hobbyists to industry professionals, we enjoy learning about new things and meeting new people, and participating in spirited debates.

Quick Navigation

User Menu

Steve Williams
Site Founder | Site Owner | Administrator
Ron Resnick
Site Co-Owner | Administrator
Julian (The Fixer)
Website Build | Marketing Managersing