CLS help in Indianapolis

[dougstrach]

I came across a pair of CLS's and wanted to jump into electrostatics with these beautiful speakers. They look perfect with not a blemish in the mylar or panels. I hooked them up and they just don't sing. I hear music, but little or no bass and it sounds like they are muffled and dull. I don't know where to start. All the shops I'm familiar with in Indianapolis won't touch them and I've reached out to Russ Knotts in Cleveland and he doesn't respond.

Anyone know where I can start with these? Anyone in Indianapolis or in the midwest that is good to check them out. I believe the panels are fine--likely need replaced due to age, but I'm thinking the problem is more in the electronics.

Any starting points would be appreciated.

Thanks,
Doug

 

[ML4Life]

Hi Doug! If they are original panels they most likely need to be replaced. You can reach out to ML and they can give you troubleshooting steps. Unfortunately in the east coast so I am not familiar with anyone locally, although ML may be able to direct you there as well.

I highly recommend the CLS's. Amazing speakers.

 

[Brad225]

Welcome to ML owners Doug.

I understand your issue. Have you called or just emailed?

 

[john65b]

The CLS will need a bit of Bass support - best filled in with a good musical sub. I have a Rel T-7i that works nicely.

The dullness could be aged panels, or underpowered amp - need an amp with lots of current capability. What amp are you using?

Are your panels separating at the exposed upper edge?

 

[dougstrach]

I'm planning on using a MC275 for these, but that amp is with Mike Samra for some work. I've got it hooked up to an Alesis RA500 that should have plenty of power--maybe not the most melodic, but good for a stand-in. All in combination with a Janis sub and an Interphase 1a crossover amp.

 

[john65b]

Unlike Quads, the CLS need lots of power - current...

Maybe someone else can offer better insight on your McIntosh amp on the CLS...

 

[Leporello]

I wouldn't pair the CLS with tube amps. They sound muffled due to the impedance hitting the floor at high frequencies. You're not going to get floor shaking bass out of them, without the sub. My CLS II's are pretty solid down to 40hz in my room, and plummet below that.

I'm unfamiliar with the Alesis RA500. The MC275 may handle low impedance better than the Latino M125, which uses a classic Dynaco output transformer. Muffled is precisely how the latter sounded. I think the Mac uses partial cathode loading and that may help. But your best bet is a 2 ohm stable solid state whose maximum power rating at 4 ohms is exactly double that at 8, indicating it behaves like a voltage source. Double again at 2, even better. Preferably one that sings. I've settled on the Parasound JC-1 monoblocks.

 

[john65b]

The Alesis RA500 is a Pro-amp. Nothing wrong with it...at 250w@4ohm / 150w@8 ohm.

Power doesn't double from 8 ohm to 4 ohm, so cannot expect it to be "qualified" to drive the crazy impedance (at higher frequencies) of the CLS to appreciable levels.

 

[Brad225]

I wouldn't pair the CLS with tube amps. They sound muffled due to the impedance hitting the floor at high frequencies. You're not going to get floor shaking bass out of them, without the sub. My CLS II's are pretty solid down to 40hz in my room, and plummet below that.

I don't think you can make that blanket statement Leporello. It totally depends on the amp.
I have used 3 different Audio Research tube amps with wonderful results. I have heard many SS amps and I don't care for the in your face sound if they can drive them reasonably.
It is a personal preference. You may just not care for the sound of tubes and thats OK.

 

[ML4Life]

I power My CLS's with MC257. Works phenomenal. Great sound.

 

[Robert D]

I power My CLS's with MC257. Works phenomenal. Great sound.

Nice. Thats a pretty definitive answer for Dougstrach.

 

[R.I.P]

Introduction:
CLS 1 manufactured after original CLS discontinued after approx. year in production. I was in contact with Martin Logan service dept. regarding availability of panel and spare parts.They have no inventory of spare parts to fit inside electronics module. Can provide only made when order CLS 1 panels. Do not have connector block that fits panel to electronic module. Very helpful with fast response time.

I recently had panels repaired. Mylar was not replaced and old Mylar not get new conductive paint. Due to age and much dust there was much carbon deposited inside perimeter of panel. The panel surface area was cleaned. Carbon was removed from edges. In addition not visible there runs a copper approx. 1 cm wide flat wire around the panel that had become detached. This was reattached.

Body:
When you say muffled do you mean dull midrange with rolled off top end. If there is low volume, weak high and low frequency reproduction, subdued midrange however without any distortion then only panel replacement is required. Because there is no distortion I would guess electronic modules are okay.

I have no personal experience using tube amps. What I have gathered from experts is that CLS 1 love valve amps and McIntosh MC 275 is a good match. If the electronic module is up to par then with new panels and MC 275 or other suitable Audio Research, Conrad Johnson amplification you will love the sonics.

Conclusion
Buy new panels only if you are know without doubt electronic module is up to par. With matching tube amp will provide sonics few have heard.

 

[Brad225]

Find yourself a good electrical technician because many of the parts are so old they need to be replaced or solder joints are bad in places.
I had the interfaces for my CLSIIz gone through by a friend and it was a huge difference. The IIz interface is not nearly as old as the CLSI obviously.

 

[Jeff Zaret]

I came across a pair of CLS's and wanted to jump into electrostatics with these beautiful speakers. They look perfect with not a blemish in the mylar or panels. I hooked them up and they just don't sing. I hear music, but little or no bass and it sounds like they are muffled and dull. I don't know where to start. All the shops I'm familiar with in Indianapolis won't touch them and I've reached out to Russ Knotts in Cleveland and he doesn't respond.

Anyone know where I can start with these? Anyone in Indianapolis or in the midwest that is good to check them out. I believe the panels are fine--likely need replaced due to age, but I'm thinking the problem is more in the electronics.

Any starting points would be appreciated.

Thanks,
Doug

Doug,
I have CLS iiZ's. These were originally IIA and upgraded. It was basically an electronics upgrade. I also have a RA-500 which I used to power my older Sequel ii's and it worked OK. It was not as good as I hoped but as you said it will work when your "main" amp is being repaired.

Have you tried to vacuum the panels? This sometimes will help a little bit. Conversely you can you high pressure air. If you have the serial numbers of the panels and electronics we can tell you the age. I have the document somewhere if you need it.

I am planning on retiring in the next few months and will be moving to the Indianapolis area so maybe if you are still having issue I can help.

Good Luck

Jeff

 

[Leporello]

I don't think you can make that blanket statement Leporello. It totally depends on the amp.
I have used 3 different Audio Research tube amps with wonderful results. I have heard many SS amps and I don't care for the in your face sound if they can drive them reasonably.
It is a personal preference. You may just not care for the sound of tubes and thats OK.

Yeah, that's why I qualified it with my experience with my particular tube amp. And indeed, one audio show demo I heard, with ML's driven by Rogue Audio tubes sounded superb. But I do stand by my statement that any classic tube amp, with an output transformer, is going to handle wild impedance swings with less aplomb than a competent solid state. You may like the softening of high frequencies due to the impedance dip, but it's not objectively accurate. And remember, we're trying to diagnose the OP's experience with muffled sound.

It has also always bothered me, from an engineering standpoint, that it is rather silly to step down the high voltage swings to low voltage/high current, then back up again. Now, one transformer to go from the plates to the ESL's? That would definitely be something worth trying! One of my fantasy projects. I'd have to get someone to design and wind the transformers, and buy panels from ML. I'd probably use the Latino chassis, if I haven't sold them by then.

There is also the possibility of directly coupling the plates to the ESL stators. That may seem elegant, but can be outright dangerous. Acoustat tried that, with one model. It wasn't a great tube amp design to begin with, though Joe Curcio offered a mod for it. It's one thing to have exposed B+ voltage on Acoustat stators, with their insulated wires supported by an outer honecomb sturcture. On ML's. I wouldn't be willing to trust my life to the paint on the stator plates.

 

[Leporello]

I came across a pair of CLS's and wanted to jump into electrostatics with these beautiful speakers. They look perfect with not a blemish in the mylar or panels. I hooked them up and they just don't sing. I hear music, but little or no bass and it sounds like they are muffled and dull. I don't know where to start. All the shops I'm familiar with in Indianapolis won't touch them and I've reached out to Russ Knotts in Cleveland and he doesn't respond.

Anyone know where I can start with these? Anyone in Indianapolis or in the midwest that is good to check them out. I believe the panels are fine--likely need replaced due to age, but I'm thinking the problem is more in the electronics.

Any starting points would be appreciated.

Thanks,
Doug

Also, some points for a newbie ESL user we may have overlooked because most of us take them for granted:

First, even though the curved ESL panel concept is, IMO, brilliant, these are still designed to a fairly narrow dispersion, about 30 degrees. This eliminates the "head in a vice" effect, but you're still going to have a relatively narrow "sweet spot". If you're not in it, they can sound muffled. ML recommends as a starting point you try toeing them in slightly, in such a way that you are "listening to" the inner third of the panels. I emphasize this is a starting point only. Full range ESL's almost always require extensive experimentation in your room to sound their best.

The other point most of us take for granted is these speakers like a lot of distance to the wall behind them. At least three feet, if you can manage it. Too close, and the diaphragm cannot vibrate freely, the cancellation between front and back waves at low frequencies will be at its worst, and the early reflections off the wall behind will screw up the stereo image.

 

[cabinum]

I have IIZ's and am currently driving mine with Carver 350's and love the results. I can testify to the difference interface tweaks make as I am still enjoying the fruits of the changes made by Brad's friend. I initially had them paired with a set of Cary SixPacs which sounded fantastic, but they were entirely underpowered and couldn't be driven very hard and sounded like they were just out of breath at moderate levels. Swapped in a set of Levinson 33H's, and they woke up, but lacked the sound that made me love the panels. The Carvers really grab a hold of the panels and make them sing. Definitely make sure you put as much power as you can behind them, be it SS or tube. I do have them paired with a Descent i, so it does help the bass, but have turned it down substantially since the Carvers arrived.

 

[john65b]

Leporello,​

Roger Sanders has an old writeup on driving ESL stators right off the plates of a tube amp (eliminating the step up transformer) to satisfying sound levels... the output tube plates were "only" around 500v, but worked... I have some old Acoustat and Quad panels laying around and my have a try one day with my Quicksilver amps...

I will have to look for that writeup...

EDIT - Found it

 

[dougstrach]

Doug,
I have CLS iiZ's. These were originally IIA and upgraded. It was basically an electronics upgrade. I also have a RA-500 which I used to power my older Sequel ii's and it worked OK. It was not as good as I hoped but as you said it will work when your "main" amp is being repaired.

Have you tried to vacuum the panels? This sometimes will help a little bit. Conversely you can you high pressure air. If you have the serial numbers of the panels and electronics we can tell you the age. I have the document somewhere if you need it.

I am planning on retiring in the next few months and will be moving to the Indianapolis area so maybe if you are still having issue I can help.

Good Luck

Jeff

Jeff, Thanks for your reply--seems like you are the only one who read my post and had some useful insight. I did vacuum the panels, but the problem increased the longer I had them plugged in. Now, I get about 10% out of 1 panel and nothing out of the other. Switching panels with the electronics, the problem follows the electronics.

I believe I have a bad T1 low-profile transformer and a potential grounding issue on one board and the other is on it's way out. I'll see if my local tech has a high-voltage probe and can work on these, which should be a very cost effective fix as compared with replacing the panels!

Why retire to Indianapolis??? Likely a very long answer, but either way, you are free to DM me once you get here and I will either still have a project or a set of CLS's that I can demo for you.

Thanks,
Doug

 

[john65b]

Are the speakers plugged into a switched mains plug? Are you sure there is power to the interface? I know this is kinda silly, but I would start there...

Whatever you do, never drive ESL speakers without the panels fully biased up, as you will fry your step up transformer. A friend plugged his Quads into a switched outlet and didn't realize this until too late...he kept raising the volume on amp and eventually destroyed his step up transformer...

So if you are getting nothing out of one panel and 10% out of other, leads me to believe you lost your bias voltage... takes a while to drop that 3800vdc on diaphragm.

So using a standard 600v Multimeter, you use it to see if panels are getting bias voltage...since the resistance of your standard multimeter will weigh down the voltage, you will read a reduced voltage - when I measured my Acoustat bias voltage (5000vdc) my multimeter read around 75vdc.


ALSO - there should be a fuse inside the Interface that powers the bias voltage - might want to check that these are good.