Hi: I heard the combo of Soundlab (model U1?) with two Spectron monoblocks with all upgardes and Joule-Electra Marienne-Electra full tube preamp. It was pure heaven. To begin with you got bass !!!! real bass. Did I say you get bass? Then the rest: gorgeous seductive midrange and silky highs. Huge soundstage (which you would get with your speakers anyway to be truthfull) and stunning imaging. Extraodinary detailed and yet "purely analog" sound.
This is one of very few combos equal (or may be even better then mine...). Soundlab (when driven correctly!!!!!) gives you real magic like M-A-G-I-K
Dob thanks for the feedback;I was starting to think it was a combination that may not be very good;I presently have m2's with upgrades and audiovalve challanger 180 monoblocks so I completely understand the magic that you are describing;thanks again.
Sound Labs do play nice bass. The trick is if the amp can deliver power into the bass frequencies as their impedance can be quite high. This is why they seem very power hungry if you have a transistor amplifier- an amp that makes 400 watts into 8 ohms will only make about 100 watts into the bass frequencies.
Its not a power issue though- 150 watts is plenty of power if the amplifier can make the power. Its a matter of impedance.
Dob's description matches pretty well to what I hear with the IcePower Bel Canto ref1000m monoblock Class D amps in my system. They seem to work well with most any speaker design it seems though if your speakers are a bottleneck to the sound, you will know it.
"Its not a power issue though- 150 watts is plenty of power if the amplifier can make the power. Its a matter of impedance "
Yep, its better to be rich and healthy then poor and sick.
The problem is that some, just some don't know how to reach there.
IcePower and Soundlabs: Honestly, I am not even sure if these amps are capable to drive these speakers without invoking protection circuitry... Very easy to test; if in the middle of music you will hear silence then yes, its your answer
For the most part solid state amps do have trouble making power on this speaker. I would not expect a class D amp to have problems with the load otherwise, just that you would want one with a lot of power (600 watts or more depending on the room) so that you don't have to push the amp.
Some of this is my own experience- I find that class D works a lot better if they aren't being pushed hard.
"I find that class D works a lot better if they aren't being pushed hard."
PRobaly true with most any SS amp but honestly, I play my BC ref1000m's pretty loud on some relatively inefficient speakers (albeit not electrostats, which are unique electronically) in a decent sized room and I have never detected them being even moderately warm, much less break a sweat. THey seem to handle things without much effort for the most part no matter what. No sign of stress or rough edges in the sound whatsover no matter what. Has not been the case with any other SS amps I have used there, which is one big reason I went to one of the biggest yet most efficient, well reviewed, and tube pre-amp friendly SS amps I could find. I had to stretch a bit to handle the cost but it was worth it.
I have heard other IcePower amps (Rowland) do a similarly nice job with Magnepans however. I can't imagine that a good design that addresses power supply around a stock Icepower amp module like these could not handle just about anything. I might be somewhat more skeptical about some amps that just stick stock Icepower modules in a box but I would expect decent results even there.
In case it would be of any significance in the present discussion, I have a Spectron with all the upgrades driving a pair of Acoustat Spectra 44. It does it with a lot of ease with firmer bass performance and overall definition than my Coda Model 11 100 watts full class A. And it remains quite cool to the touch. The preamp is a CJ Premier 16 LS2 and I find the mix quite listenable too.
I could add a class D amp, at least a higher quality one, is also a plus in terms of silent running, which is detrimental in retrieving all the details of a recording for which electrostats are mostly famous.
Ralph it would seem to me that the D class amps would have a hard time with the soundlab speaker because they are so compact without weight; this to me says the power supply section would be lacking and not be able to make the power as the speaker starts to demand it.I have never heard a d class amp on any speaker but this is the area of these amps that I can't grasp vs the tube or solid state amp with a huge and heavy power supply section;maybe I am just of the old school and behind the times on this area of the hobby.
My understanding is the efficiency of the high speed switching design of
the class d amp is what enables its compact size and weight including that
of the power supply compared to similar power rated class a or class a/b.
It is really a major technical step forward these days in amp size, weight
power and performance compared to older design approaches. Very
"I find that class D works a lot better if they aren't being pushed hard."
For most class D amp its true. However, Mark Levinson has huge power supplies. Jeff Rowland has very large, Daniel Weiss amps are very powerful too and my Spectron has 3500 watt peak power (and stable to 0.1 Ohm load)
It has almost nothing to do with output stage (be it class D or other calss) - only one thing is important, the temperature should not raise above safe operatating levels.
The weight of the power supplies is "important" only in linear PSU but in switching like that of Jeff Rowland (not ICE Power, sorry) the weight is low.
Among class D I mentioned above, Mark levinson cost $50k, Weiss $30k, Jeff Rowland $15k and Spectron with all upgardes about $5.5k or in monoblock mode - $11k. You pay for quality...
Class D amps get away with "lighter" power supplies because they are filtering at many KHz instead of the 60 -120 Hz of linear supplies. Thus, they can use much smaller capacitors for a given current or power rating.
Look at PC power supplies, for example, which use a similar switching technology. They currently build 1000W-1500W power supplies for computers that fit in a box 6"x6"x8". And these run at 100% continuous power, as opposed to audio systems where the average power is about 1/10 of the max at full output.
That said, I have always been suspicious of the audio performance for such amplifiers, except in subwoofer applications. Maybe I'm old fashioned, but if Class A/B is inferior to Class A, the class D has got to be inferior to Class A/B, simply because it operates completely out of the linear range of the output devices (hard on to hard off).
I'm not sure why the PC type of switching supply is not used more for audio (actually it is in car audio, but only there), but I suspect the audible side effects of such supplies are intolerable when compared to old fashioned linear supplies with thousands of microfarads of capcitance.
They are the cheapest way to make really big power, but I am not sure if they are the best.
You may find the class D will strip some harmonic texture compared to a tube, & there can be a "cheapness" in the treble which can be addressed somewhat. But if you have some tone control on you xovers like the big Soundlabs, you may be able to dial in some warmth to help this slight starkness in the highs.
I also found if you use the "MW" setting on the PS audio regenerators it helps sweeten things too. But in return you will get an enormous, solid soundstage with effortless dynamics & very low distortion & absolutely no noise.
They can be great.
I want to thank everyone who has responded thus far.
Mapman, If you are not heating up the amp then you probably have no worries. So you have enough power with your speakers.
My rule of thumb with most amps is you want more power than you will be able to use with the speaker you are using. But I have a different rule with Class D amps- they should be powerful enough that they do not heat up even if used all day, at any volume you care to experience.