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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
 
Thanks for all of your responses. I learned a lot. Grannyring I will definitely take your advice. I am going to try the suggested amps until I find one I really like. I was looking at a 600x2 on ebay but it was pulled from the auction. I am also looking at the Odyssey. No Innersound or CJ in sight or price range. Ideally, I am going to sell some of my stuff to allow me to purchase two amps simultaneously to compare/sell. I will be patient as it appears that the amps only show up sporadically. Of course these funds will likely get siphoned towards college tuition. I can always use the other amp on the B-1S until I settle on a choice. Here's hoping the economy starts improving!

Perhaps my next topic will be preamps/room correction but I am not prepared for that now.
atmasphere's avatar
atmasphere
11,856 posts
 
Grannyring, what mod did you perform? Did you remove the big resistor?
grannyring's avatar
grannyring
6,510 posts
 
Hi Atmasphere, I have done them all including bypassing the brilliance knob, biwire option, cap value and quality rolling and reducing the resistance. I have not totally removed the shunt resistor as that would not work with my SS amps as you know.

I just read all the NEW stuff going on at the SLOG and WOW! Seems many good things are happening with SL's! New transformers and backplate changes as well as totally removing the shunt resistor as a possible mod with tube amps only. Well, I wish I had the MA1's still as I would remove that 8 ohm resistor and play! I bet the MA1's would not clip with that mod.

I wish I still had the speakers and the MA1's as it was the best sound I ever had up to 85db. Problem was the amps would clip too fast for any loud listening. Seems there may well be an answer that is pretty darn simple.
atmasphere's avatar
atmasphere
11,856 posts
 
Grannyring, from what I understand that shunt resistor is a problem for any amplifier, even transistors. There is a reason it is rated for so many watts- amplifier power is used to heat it up. It does not matter what kind of amp you have.

If you remove it you will find that you need less power to play the speaker and it will sound better too. It is this mod that allows the MA-1 to play that speaker with volume. Take a look at this link- its the one with the photo: http://www.atma-sphere.com/AboutUs#Feedback

After the resistor is removed, the cap value can be reduced. This prevents the HF transformer from saturating.
You can PM more more info if you like.
bpwalsh
1,207 posts
 
The backplates on the U-1PXs here are going to Sound Lab very soon for upgrading to the new Consummate version and should be here later in the month. Any and all are invited to come for a listen here in the Chicago area. I can be contacted for pricing which should be known shortly.
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