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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
61 responses Add your response
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
11,566 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
11,566 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
11,566 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
atmasphere's avatar
atmasphere
11,566 posts
 
I think you will find that the simpler you can make your system, the better chance you have of getting it to sound right.

Good Luck!
gwho OP
47 posts
 
Thanks for all your help. It is greatly appreciated.
gwho OP
47 posts
 
Grannyring,

I was wondering if you might give me your subjective view of the modifications you made to the soundlab backplate. What would the priority be as far as bang for the buck that made significant improvement to the sound.

You were correct that when the sunfire 600x2 goes on sale it does not last long. I did listen to a sunfire 400x7 on my system (just running two channel) and it sounded excellent. I'm sure the 600x2 will sound even better.

Any input would be appreciated.

Gwho
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