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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
11,803 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
1,202 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.
grannyring's avatar
grannyring
6,479 posts
 
Atmasphere, I have read that if you remove the shunt resistor when using a high powered SS amp you can damage (saturate) the transformer on the SL speaker. This is not the case with tube amps and the technical explanation goes on from there.....I'm not smart enough to follow it yet......but learning....
gwho OP
47 posts
 
Here is a brief update. First, thanks for all the suggestions. I will be purchasing and comparing the suggested amplifiers. Ideally, I would like to have two different amps for comparison over the long term. Cull out the loser and move on to the next until settling on an amp for a while. I am looking for the innersound, sunfire, and perhaps the cj. I will be patient. I can probably pick up the acoustat or the hafler 9500 on the cheap for a test run as these are substantially older amps. I was able to find and pick up the Odyssey Monos within my budget. Obviously, these have the advantage of no power supply interaction between channels. They will have the upgraded transformer, 360K uf of capacitance per amplifier, and the Kismet (latest version) boards so they should be able to deliver power to a low impedance load. This is a newer amp so issues related to device component aging will be minimal. I have an older set of 1M straightwire maestros ic for connecting the amps to the speakers that I will be using (these came with my speakers).

My next question relates to preamplifiers. I am only going to be listening to music through a server. My goal is to just listen to music instead of fussing with the system day and night. Right now I have the squeezebox touch device with CDs converted to flac. I am also interested in devices having the ability to support room eq. I want simplicity so a combo device will be my compromise. The devices that come to mind are the Integra dhc-80.2, tact-2.2x, and lyngdorf. I can get these used within my budget. Although I do not have any sacds and the like this might be of interest to me in the future. Would I go wrong with any of these DSP pre-amps or any other suggestions?
atmasphere's avatar
atmasphere
11,803 posts
 
Stay away from room EQ! If you want to complicate things (which you say you don't want to do) EQ is a good place to start. The problem you are up against is that you are dealing with a very transparent speaker, and the effects of DSP are easily audible on it. Yes, you may get the frequency response in the room to be flatter, but you will pay a big price sonically to get there. IMO/IME its not worth it unless you have cheap speakers.

The other thing you want to consider is that digital volume controls rob the signal of resolution at lower volumes. Again, consider the fact that the Sound Lab is one of the most revealing speakers made. You really do have to have your ducks in a row when you set them up, if you also want them to sound like music. So something with a good analog volume control is advised, perhaps even an active line stage to deal with that reality.
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