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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
grannyring's avatar
grannyring
6,464 posts
 
Having owned your speaker, modified it, used many amps on it etc... I can
tell you what your best two options are by a proverbial mile.

The Sunfire Signature 600 stereo amp. This one is just special with your
speaker. Sounds fantastic and bested amps costing up to $20,000.

One other fantastic choice which I also paired with your speaker is a
Conrad Johnson 2500a. It was also a special match.

I liked these amps better then the PARASOUND JC1s and the Atmasphere
MA1's and that must tell you something as both these amps are wonderful
in their own right.

If you find a Sig600 send it to the only authorized service center for Carver
and have Bill work on it for $400. He will go through the amp and do all it
needs and you can be sure it will sound better than the way you purchased
it. The power supply filter caps will most likely be replaced plus the voltage
rails adjusted for better performance. Mine had a whole new right channel
board put in and many other parts replaced. It came back sounding
absolutely amazing.

Good amps mentioned above, but I know both of these sound better then
the ESL 300 mentioned. Your speaker has impedances down to 2 ohms in
the highs and up into the 50's in the bass. SS amps don't like impedances
that go this high and put out only a small fraction of their rated power in the
bass area of your speaker. The Carver drives them with ease and never
even gets warm. The CJ surprised me and also drove them very well.

I also tried some digital amps and found both the Sunfire and CJ had more
body, warmth and scale.

Good luck on your search.
gwho OP
47 posts
 
Grannyring,

I have read your previous comments on amplifier choices for Soundlabs and they were among those that influenced my direction. I have no doubt that the Innersound or the Sunfire are among the few SS amplifiers within my budget that can drive the Soundlabs. You specifically cite the 600Wx2 Sunfire. I believe that my system differed from yours slightly in that I have the B-1S woofer. A portion of the bass output will be coming from the subwoofer. I was considering driving the speakers with the 425Wx5 amplifier. From the specs the 425x5 can deliver the current/power required for the high frequency. The two channels driving the B-1S would be loafing. Dr. West told me to limit the power to the B-1s to 400W or less. I guess what I am saying is that I may not need the voltage swing of the 600Wx2 to deliver the lowend punch. Is my conclusion wrong or would there be a substantial sonic difference between the two amps in my system.

Could anyone articulate the difference in amplifier sq between the innersound and sunfire?

A general question to others who have helped. What frequency should I crossover the B-1S at? At what freq does bass go non-directional.

As usual thanks for all the input.
tthomas
36 posts
 
I have been using Odyssey mono blocks on SoundLab speakers for years. I too have college bills coming in and can't afford to consider upgrading much of anything at this time. The Odyssey's have been amazing. I have never regretted purchasing them. Used ones should be in your price range.
grannyring's avatar
grannyring
6,464 posts
 
I think the 600 is a better amp as the transformer and power supply drive two channels only and the same hardware has to drive all of the multi channels in the other amp. Just my feeling however. I also ran two subs with my M1's, but drove my SL's full range and only used the subs at 30 htz and below. I like the bass on the SL speakers and used the subs as just a little added foundation.
gwho OP
47 posts
 
Thanks for the input. I've never heard of odyssey amps. I will look into them. A more robust power supply is definitely an advantage vs the 425x5. I will consider the 600w Sunfire. I was thinking of crossing at a higher frequency something like 60 or 80hz. There is not a lot space between my speakers as the room is only 15 feet wide where the speakers are located. The room does open up to over 20-30 feet wide and is about 50' long and over 12' high.
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