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Soundlab Speakers - Budget Amp Suggestions

I have tried to read as much as possible about different types of amplifiers capable of driving electrostatic speakers. Thanks to everyone for the great articles and discussions. In particular, I am looking for a ss amplifier that can drive Soundlab speakers. The Soundlabs have a low impedance at high frequencies and a high impedance at low frequencies. A high power ss amp that can drive difficult loads appears to be the ticket (I'm not interested in tube amps). High current is needed for the high frequency/low impedance (but not necessarily high power) while the high voltage (albeit at lower power) can drive the high impedance at low frequencies.

While looking for speakers I came across the Soundlab speakers and really liked the sound. I basically blew my budget on them, which for me is not a bad compromise because I don't want the speakers to be the weak link in the chain.

So this is what I have:
1. Two Soundlab A-1 speakers (1992 vintage)
2. One Soundlab B-1S subwoofer (pre 1990) - This is a stereo subwoofer having two separate inputs to drive each interior panel.
3. The A-1s have the toroidal and impedance upgrade.
4. I had all the speakers reskinned with the px mylar.

There will be some type of crossover between the A-1s and the B-1S (the frequency and type of crossover is undetermined at the moment)

I believe that having the B-1S reduces some of the constraint of having the highest power amplifier to drive the A-1s (e.g. 500-600W) since a lot of the bass will be coming from the B-1S. I was told to limit the power to the B-1S to a 400W or less ss amplifier. I am thinking that perhaps I could get away with a lower power amplifier for the A-1s because of this scheme. Please let me know if I am wrong.

As I said my budget is limited. I have about 1.2K and perhaps up to 2K to spend on an amp. The amp I have targeted is a Sunfire Cinema Grand Series II 5-Channel amplifier that outputs 425W a channel. The channels driving the B-1S won't be delivering a lot of power as the impedance is 16 to over 30 ohms. The amp should be able to drive the A-1s adequately. As a side note I have a couple of amps (Crown K1 or Citation 7.1 which output between 300-400W) that I could use to drive the B-1S if needed.

Are there some vintage or other budget amps that I should be considering. Is my analysis wrong? Any suggestions on crossover frequency? I appreciate any and all input. I want to thank every one in advance for their thoughts.

Regards,
GWHO

gwho
gwho OP
47 posts
 
Tthomas I did look up the Odyssey mono blocks. The reviews on these amps are quite impressive. I believe they should be able to handle the low impedance load of the Soundlab speakers. The other suggested amps can all provide high voltage excursions along with driving low impedance loads. My concern would be the ability to produce low frequency sounds with authority. I am currently using a 150W amp with the A-1s and for me the bass does not seem in balance with the rest of the sound coming out of the speaker. My room and system is far from being set up correctly so you have to take what I say with a grain of salt.

Have you been satisfied with the bass and bass transient response from the Odyssey since you have lived with these amps and Soundlab speakers? Does it change with volume level?

Thanks!
atmasphere's avatar
atmasphere
11,803 posts
 
Grannyring, just FWIW the Atma-Sphere MA-1 would have been underpowered on many of the older Sound Labs.

BTW, Roger West has a new back panel that should be available as an update to any A-1 or similar Sound Lab. It seems to be based on a lot of the conversation that has been going on on some of the forums regarding the drivability, impedance and mods that can be done to the older back panels. The result *should* be a speaker that is a lot easier to drive!

People that have done some of the mods have thus been able to get the MA-1 to work fine. But others have reported that they got a lot better drivability when using transistor amps like the Parasound JC-1 as well.

You might want to read this thread and the one above it on audioasylum, there is a lot of info on the mods done to the back panel:
http://www.audioasylum.com/forums/otl/messages/3/35023.html

For someone trying to drive used Sound Labs on a budget I would expect this to be required reading.
grannyring's avatar
grannyring
6,479 posts
 
Atmasphere, you are spot on and yes the SL's needed more power. I bet the MA2's would be heaven!

I did complete the mods mentioned on my A1's as well as several other mods found on the now pretty quiet SL forum. Roger West was very helpful and actually drew me an easy diagram to follow. He even put my name on the schematic! Great guy!
stringreen's avatar
stringreen
6,468 posts
 
If you get top the line speakers why oh why would you be shopping for a budget amp. Why put cheap tires on a performance sports car.
gwho OP
47 posts
 
Stringreen,

I do have a budget and I chose to spend most of it on the speakers. The speakers that I purchased are twenty years old although they do sound good. They are not current top of the line. I believe that my choice of amplifier is critical because of the difficult load the Soundlab imposes. The suggestions provided by the contributors to the thread are all good. The Innersound, Sunfire, TNT-200, and Odyssey Monos amplifiers have all been proven to have good SQ with the Soundlabs. Moreover, they are all within reach of my budget which does not make any of them a compromise. Just good amps for my speakers.
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