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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
atmasphere's avatar
atmasphere
11,901 posts
 
If you are on a budget and have A1s and B1s, had it ever occurred to you to sell the B1s and use that to finance an amplifier that can drive the A1s properly? That would seem to be a lot more expedient than trying to find two competent amplifiers to drive both the top and the bottom!

BTW you will need similar power from both amplifiers...

100-200Hz is good for the crossover point. A1s by themselves go down to 22Hz. The subwoofer is ostensibly not used to deepen the bass so much as it is to get excursion off of the A1 panel so it can be more transparent. But you can do the same thing by using the right electronics on just the A1.

How big is your room??
gwho OP
47 posts
 
That thought did occur to me but I would purse that after I have played with the B-1S a little bit. My speakers are in what was our formal dining room. It is probably 15 feet wide. The speakers look like a wall that hides the electronics which makes the wife happy. I have a couple of real traps on stands in the corners (no other traps because of waf but I might be able to put one behind the B1s) The speakers fire into my living room that is adjacent to dining room. The most I can move the speakers from the back wall is about 5-6'. The ceiling in the dining room is 12 ft high. The living room is much wider probably 20-30 ft wide and extends at least another 30 feet from the dining room (although where I would sit is about 16- 20 feet from the speakers). The ceiling in the living room opens up into a loft area that is probably 15-20 feet high in places (high pitched roof).
gwho OP
47 posts
 
One question. I don't understand your point about both amplifier needing similar power. From what Dr West told me the B1s has an impedance of about 16 ohms to over 30 ohms. I think it is spec at being able to handle 400 watts but Dr West told me not to use an amplifier over 400W. I would assume that I need voltage not high power for the B1s. Of course if I am using a transistor amp the only way I will get the voltage is if I get a high power amp.
atmasphere's avatar
atmasphere
11,901 posts
 
Right, and you will find that you have a similar problem with the A1. So to drive them you will need two pair of identical amps, otherwise the weaker amp will describe the maximum volume level.

If I were you I would get rid of the B1s and concentrate on just the A1s and the amps for it. Then you would have less equipment so you could still hide most of it except the front end (preamp/dac/CDP/whatever).
gwho OP
47 posts
 
Atmasphere,

I appreciate the sage advice. What you say makes a lot of sense. Although I won't get rid of the B1-S just yet. I definitely won't be buying anything for the B-1S (e.g. amp/crossover). I will concentrate on the equipment for the A-1s. I'm beginning to look at some DAC-Preamps. I will definitely consider the Ayre Dac.

Best Regards,
Gwho
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