Soundlab A3s and thoughts.

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!

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.