SOUNDLAB ULTIMATE 545

Pinotnoir, I have 645-8's, 8 foot tall 645s. Duke is correct about Atma-Sphere but as a rule they work much better with solid state amps. The problem for most tube amps is the extremely low impedance at high frequencies. This requires a LOT of current. Big solid state amps with over built output stages work best, particularly class A. The only exception I know of is the Atma-Sphere amps The two amps they have shown with are the Atmasphere either MA1 or MA 2, atmasphere would know, Ralph you out there? The other amp is the Parasound JC1 which is what I am using. But , I am debating getting MA2's and moving the JC1's to subwoofer duty. The JC 1+'s are about 1/2 the price of the MA2's. The efficiency of the 545's is just a little less than my speakers so you still need the power. Both amps get just as hot which is very so I hope you have AC.  I highly recommend you get a room control Preamp and two subwoofers down the line. You will increase your headroom at least 6 dB, lower distortion noticeably and you will be able to match the frequency response of the speakers/room perfectly. The result will be an outstanding image. I you go down this road give me a shout and we can talk about it. 

mijostyn4: Fisrt of all, congrats for your system.
Thanks for your advising offer. As jperry said, first I´ll have to run with my Antileon and I let you know first impressions.

Roxy54: I´m lucky with the gift to enjoy music, 50% melomaniac-50% audiophilic. Let me know your equipment components

Duke is correct about Atma-Sphere but as a rule they work much better with solid state amps. The problem for most tube amps is the extremely low impedance at high frequencies. This requires a LOT of current. Big solid state amps with over built output stages work best, particularly class A. The only exception I know of is the Atma-Sphere amps The two amps they have shown with are the Atmasphere either MA1 or MA 2, atmasphere would know, Ralph you out there?

The impedance thing is a real challenge for solid state amps! You don’t need a lot of current when the speaker is at its lowest impedance since that is at 20KHz.

But in the bass the impedance is 30 ohms. This means that a solid state amp rated at 600 watts will make around 160 watts. This is why a tube amp can keep up on this speaker with a solid state amp rated at 4x the power. And this is the reason that if you go solid state you need such a high power one- not because of the highs but because the solid state amp will have troubles making power in the bass. Our MA-2 makes 220 watts on that speaker; to keep up a solid state amp would need to make nearly 900 watts!

The older Sound Labs had a dip in the impedance curve because of a simulation error when the crossover was designed about 25 years ago. About 6-7 years ago a number of our customers sent some actual measured data to Dr. West that convinced him a crossover redesign was needed- thus the Toroidal 2 backplate. This in turn caused the speaker to be much easier to drive and so you could do with our MA-1 what took our MA-2 on the older speakers.


One thing about almost all ESLs: because they are not drivers in a box, and thus the impedance peak in the bass is not the result of a driver at resonance, they don’t follow the same rules that most box speakers do. Most box speakers are designed around the idea that the speaker is ’voltage driven’ which is to say that the amplifier driving them is a ’voltage source’ in that it can provide the same voltage regardless of the impedance of the load. Put another way, such an amplifier can double power as impedance is halved. ESLs OTOH need the amp to be able to put out the same *power* regardless of the load rather than the same voltage. For this you need an amplifier that has a bit higher output impedance but also can make some serious power. For more on this topic see
http://www.atma-sphere.com/en/resources-paradigms-in-amplifier-design.html
The Sound Lab is a bit of an exception here- unlike most ESLs its equipped with controls that allow you to adapt the speaker to a variety of amplifiers. Usually with solid state amps you want to set the bass controls for +3 or +6dB (keeping in mind that the wall behind the speaker will be at least 5 feet away) with the Brilliance turned down a bit. With our amps at the other extreme the bass setting is usually at -3dB while the Brilliance is set all the way up.


When you see controls like this on the back of any speaker, that’s a sign that the speaker is performing according to Power Paradigm (see link above) rules.

Finally as anyone with exposure to ESLs knows, Sound Labs are some of the fastest and most revealing speakers ever made price no object. For this reason its really important that the amplifier and preamp have similar transparency- you need your ducks in a row with this speaker; its transparency reveals amplifier flaws with ease. I would hesitate to use a solid state amp on this speaker for the simple reason that the distortion of solid state (which causes solid state amps to sound bright and harsh) will be compounded by the low impedance of the speaker at high frequencies, causing the amp to also be tonally bright.

hi pinotnoir

Thinking about the CAT JL-7. A very nice match for SLs.But the Atma-Sphere MA-1 or MA-2 would also be excellent.
I am a big Atma-Sphere fan.
The output transformers in the CAT are superb but there is nothing like an OTL. And if you play vinyl, the Atma-Sphere MP-1 preamp wt built in phono stage is one of the best ways to play vinyl.
I have one.
And you can always follow what Ralph says.