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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
11,796 posts
 
If your amplifier supports balanced inputs then I would feed it with a balanced source.

The reason there are balanced cables and a balanced system is that it offers you the ability to have the cables drop out of the overall system sound. I am sure by now you have noticed that you can hear differences in interconnect cables; the balanced line system was devised to eliminate that problem and it does it very well if you adhere to the balanced line standards.

I of course like tubes more than transistors; if you are looking at a preamp I would recommend a balanced tube preamp. If you are looking at DACs (and no preamp), you will want to find one with a balanced output and an analog volume control (digital controls reduce resolution as you turn them down). I think Ayre makes such a unit.
gwho OP
47 posts
 
Thank you I will look into the Ayre. The Benchmark HDR has an analog volume control but the latest version has a digital volume control. I appreciate the advice. Is there any reason to use a preamp with a Dac when Dacs now have volume controls. I would assume adding more devices into the signal path cannot be good.
atmasphere's avatar
atmasphere
11,796 posts
 
It depends on a lot of factors. If the DAC has trouble driving cables you might be better off with a good line section, especially if the amps are far apart. Also, some DACs don't have volume controls... and you might want more than just that one input.

The Sound Labs can be pretty convincing. You might like them. If that is the case you may find yourself looking at ways to get more out of them. One way to do that is play LPs. You may not believe it now but you may someday find yourself playing vinyl. If that happens you certainly will want a proper preamp.
gwho OP
47 posts
 
Excellent advice. I absolutely agree with you that I may get eventually get back to playing vinyl. I have several hundred albums in storage at the moment. Moreover, I don't see what I am doing as an end game. More like a beginning. It is good to know that my speakers are not the limiting factor (even with their age) and can be improved a lot by playing with components of the system. I want to put my initial system together based on the collective ear of those who have similar systems to cobble together something that is adequate within my budget. I will play around with speaker placement and room treatments to try to get that right. Once I put my kids through college, I will be able to direct some funds towards a much improved system.

I will likely look into Dacs like the Ayre that have a volume control. I'm still wrestling with how to crossover to the B-1S. One suggestion was to crossover at the lowest octave (40hz). I could use an analog crossover to achieve this but would wonder if this would be the limiting factor coloring the sound (e.g. defeating the purpose of using a Dac like the Ayre). I could similarly crossover in the digital domain but then would require two Dacs. Dr West at Soundlab told me that several people he knows runs them without crossovers with good results. Some type of parametric eq might have to be used. He also told me to pay attention to phase in using any type of crossover. One other alternative proposed by Dr. West was to disconnect the bass transformer in the A-1s. He said the B-1s would integrate well in that scenario because it goes up to 350Hz. My own thoughts is that I would want to keep the bass directional (coming from the A-1s). I don't know at what frequency bass becomes non-directional.
atmasphere's avatar
atmasphere
11,796 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??
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