Soundlab A3s and thoughts.

I know two people that own Soundlabs. One uses Red Rose tube amplifiers and the other uses Wolcott tube amplifiers.

Both systems sound great

Good luck with your SoundLabs

I used to run the big Atma Sphere on my SL, but that was many years ago. Not sure if  Atma Sphere is still around.

Atma Sphere is very much still around and they are very popular with Soundlabs owners but they are very expensive even used. For ESLs the Soundlabs are very easy to drive. You want at least 100 watts/ch. Between 1-2 K is tough. A used Parasound amp might come in under 2K.
You will have to play the used market and see what is available. If you can find an AB amp that gives you the first 10 watts class A that would be great. 

I’ve got a line magnetic 218ia here in another system (845 output tubes) I’ll try that at very low volumes. I’m a bit of an SET guy. So these are a departure. The 518 is only about 30 Watts so I’m not expecting it to go well. Failing that there is a Nad c390dd local that is within budget. There is also a Bryston 4bb st on eBay that might be a goer !!! Thanks all for your thoughts. 

Call Dr. Roger West, designer and maker of SoundLab speakers, and ask him for recommendations.

Wow, go straight to the source.... i hadn’t even considered that as an option. when i’ve got them, ( i pick them up tomorrow ) and i can quote the serial numbers , I’ll do that. Thanks for the advice.

https://www.stereophile.com/content/sound-lab-3-loudspeaker-specifications

The measured sensitivity was around 76dB/1m/1w (vs. mfr 88dB). Look for a high-powered SS for this model.

That may be with the old transformer. The newer toroids are more efficient. Myron’s set could be either but he can get them upgraded if need be. The newer PX panels are also more efficient.

My speakers are original A3s with the old transformers. So as inefficient as they can be..... still sounded great even with my limited amp........ Panels were a little crackly but I tuned this out with the bias adjuster. I’m not quite sure what this does, but I’ve asked soundlab for a Manual so hopefully I’ll learn and hopefully I’ve not done anything bad.

I picked up my speakers today, and roughly set them up this evening. With my Line Magnetic 518ia 22 watts SET. I wasn’t expecting much , but this combination gave me some of the most convincing presentation of female vocals that ive heard. Case of you (Diana Krall/live in Paris CD) was the most present I’ve ever heard it. Fantastic. Volume was not a problem either. There are limitations however. The little line Magnetic could not play extended, low, electronic bass notes without Producing physical vibrating of the panel. Short transient low bass was fine but long electronic bass produced a chuffing at medium to high volume. Lowering the Volume removed this problem. I’m hoping that a higher power amp will eliminate this issue. So I’m now thinking of the Line Magnetic lm150ia, with 4 KT150s producing 100watts. Just because I’ve liked their products so far. There is also I Nad C390 DD for sale locally that I’m interested in ( I used the M51 dac for a while and liked it ). It’ll run 150watts continuous into 4 ohms with x3 that peak. I’m curious about that too. DD amp, dac and pre all in one. Very different to what I’d usually go for but maybe a change is as good as a rest. We shall see.

thanks for your interest. 

I’ve had my pair of Soundlabs M-645s for about 8 months now. They were brand new so newest bass focus panels and transformers. I still use a Pass Labs 350.8 for juice. They need the power. 

The bias is critical! This has to be set correctly before using the speakers. Not setting it properly can damage the speaker. It directly effects efficiency, and controls the amount of voltage applied to the panel.

If you google search setting the bias on Soundlabs you will get some direction. There shouldn’t be any continuous crackling or cracking, that means the bias is too high. 

Some people set the bias to a point where cracklings can be heard intermittently and very close to the speaker. This gives you better efficiency. 

I lower mine just till I hear the crackling stop completely. Lower efficiency, but potential longer panel life. 

I also have mine on a switched outlet so that I can turn them off when not in use. YMMV, and I don’t know if Dr. West recommends one way or the other. 

Enjoy the speakers!

Ralph at Atma-sphere is your man. Not only does his equipment sound wonderful but he also knows of a few tweaks on the older SLs that can improve the speaker. Whenever I have heard the SLs sound really good they have been driven by tubes. At one CES they were driven by some very expensive European SS amps and I think this sounded good but Bob Crump was talking so loud in the background I couldnt concentrate.

The comments by @kingdeezie are spot on.  As a long time owner of A1's with the old transformers, and then updating to the newer back panels, the sound is magnificent with big tube amps.  These speakers and tube amps are a match made in heaven.

I adjust the bias similar to what was described above: 1) Turn the bias pot clockwise until the crackling sound just starts; 2) Identify the setting with the hour on a clock, e.g., 11 o'clock: 3: Turn the bias counter-clockwise to the equivalent of the clock's previous hour to the one identified in step 3, i.e., 10 o'clock; 4) This process should allow you to be near the highest sensitivity without always needing to tweak the bias which is also sensitive to humidity changes throughout the year.

Hope this helps.  And enjoy!

John

jafox has it right. The setting depends entirely on humidity. You turn up the bias (diaphragm voltage) until you hear arching then back off until it stops. You might hear some arching when it rains! 
jafox you do not want to turn the speakers off. First of all they draw almost no current as there is no current flow you are just putting a charge on the diaphragm. It costs nothing to keep them on. There is a period of time for the charge on the diaphragm to settle down perhaps 10 minutes or so. Keeping the speakers on does not decrease the life of the speakers at all. Letting them arch continuously does not decrease the life span at all it just sounds snappy. In order to damage a Soundlabs panel you would have to take an ice pick to it.

Hi All, Dr West replied to my email personally Welcoming me to the Soundlab family and sending me the user manual. The Manual states that the cracking noise cannot damage the panel. In fact the bias procedure asks you to turn the adjuster all the way clockwise then back off until you cant hear any cracking. However Ive just done as you suggested which is to turn until cracking is heard and then back off until it goes away. The Manual Also says that good results can be expected with OTL amps, which indeed ls Ralphs( Atmas) area. Ive had some interesting discussions with Ralph in the last few years. I'm sure his amps would be a good match. The speakers continue to surprise in their presentation even with my little old 22watt SET as long as I don't try to push the volume on Electronic Bass heavy tracks. Leonard Cohen sounds fabulous. I'll check in from time to time and let you know progress re amps and so on. There is a Bryston Local that might fit the bill. Thanks all for your thoughts and advice.

Myron.