SOUNDLAB ULTIMATE 545
I’ve been involved with SoundLabs since 1999 and in my experience Atma-Sphere amps are an especially good match with them. As a new dealer I was frustrated that SoundLab wasn’t giving me an amplifier recommendation. So I asked a different question: What amplifier manufacturers have you shown with? Well that was the right question - they went off about Atma-Sphere, so that was the first amplifier line I added, and twenty plus years later is still my first choice. Duke dealer disclaimer |
Thanks a lot for your help. jperrry-I´ve not heard U-545 with my Gryphon, because they are on the way. Obviously, I´ll use my Amp, but I want to be informed about "valve sound" to feed the best way this -for me- special speakers. Today I´ve ML Aerius, but they are hybrid concept, and I really want to enjoy pure ELS. mglik- you mean JL-5 or JL-7? audiokinesis- can you tell the Atma model you´re using? |
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. |
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. |
@atmasphere , While technically true, high powered Solid state amps Like the JC1 do just fine to 105 dB (as high as I have gone) for several reasons. The JC1s due to a programming error I made absolutely fried the high frequency brilliance control and I mean barbequed BLACK and I had no idea this was happening until I smelled smoke. The JC1s merrily baked along without so much as a whimper. Tough amps. Next, while the Soundlabs are capable of making plenty of bass the long excursions required below 100 Hz doppler distort everything else the speaker does. I am of the firm belief, know it for an absolute fact, that full range ESLs sound even better, much better, if you use them with subwoofers. This cures the high impedance problem at low frequencies also. The 105 dB is without subwoofers. With subwoofers lord knows how loud you can go, certainly right past the threshold of pain. I would bet the subwoofers would be the limiting factor. Having said all this there are quite a few Sound Labs owners who are convinced the MA 2 is the best amp to drive them. Hopefully, after I recover from dumping $50K into my system this year and the house renovation required by my wife (her part of the deal) I will be able to afford your amps and maybe a Dohmann Helix and a new Master Bath :-) pinotnoir, The Antileon should be more than adequate for the time being. I would bet even better than most tube amplifiers with the exception of Ralph's amps. It is class A and 150 watt/ch. I bet it goes even higher in AB. However, next time around regardless of which amps you buy, get mono amps and place them right behind the speakers. This gives you the shortest speaker wires possible, a huge advantage with speakers that have low impedances. You should also run balanced cables to the amps. |
Hi mglik: Thanks again, You´re right, I only play vinyl. Sound in KRONOS PRO and his KRONOS REFERENCE PHONO TUBE PREAMPLIFIER give me a sound that any digital source I´ve tried can´t match. I´ll try the sound that will emerge from SL-U545 with my Antileon (Dual mono class A 150w amplifier with SL-U545), but the goal will be to feed the system with tubes. Let you know |
mijostyn: Hope you and your wife enjoy the new house renovation. Thanks for your masterclass, take taking note of every detail. Before you go forward, give a chance to KRONOS TURNTABLE. My experience (and humble opinion) with "deep vinyl track" provided translate to 5ft dimension. A complete concept vinyl system reproduction. |
While technically true, high powered Solid state amps Like the JC1 do just fine to 105 dB (as high as I have gone) for several reasons. The JC1s due to a programming error I made absolutely fried the high frequency brilliance control and I mean barbequed BLACK and I had no idea this was happening until I smelled smoke. The JC1s merrily baked along without so much as a whimper. Tough amps.There is a reason Sound Lab made the B1 subwoofer, which was the size of the A1s they made at the time (back in the 1990s). But the use of subs isn't something limited to Sound Labs- many speakers benefit from not having lots of excursion. You have confirmed my comment- in order to work with Sound Labs your solid state amplifier needs to be high power. Since the impedance of almost any ESL varies by about 9;1 to 10:1 from the bass to 20KHz, quite often the solid state amp is making far too much power at 20KHz (A high power amp can probably double power as impedance is halved, but ESLs don't work that way, they need the same power regardless of impedance at a particular frequency in order to make the same sound pressure). Since you have to throttle it back somehow, the Brilliance control becomes a target as it has to dissipate some energy. The trick of course is finding a solid state amp of that sort of power that simultaneously actually sounds like music (instead of like electronics); traditional class AB designs can be challenged in this area due to a lack of feedback at higher frequencies- which causes them to be bright and harsh (due to distortion) as I mentioned in my prior post. Its this particular problem which is why when distortion measurements are published, they are only measured at 100Hz. 1KHz and 10KHz distortion specs are usually not measured or published, but if they were you'd see that the distortion rises with frequency. This lack is caused by inadequate Gain Bandwidth Product, which is engineering gobbledygook for "the amp runs out of feedback at higher frequencies". You can't just add more feedback- that takes more gain, part of that Gain Bandwidth product thing, and at some point all the frequency poles in the amp cause so much phase shift that at a certain frequency the feedback is positive rather than negative so the amp can oscillate. The engineering expression for this is 'the phase margin of the amp has been exceeded'. This is part of why the Brilliance control is so important on the Sound Lab when using solid state amps- you have to tone down both the excess energy and the brightness caused by distortion. |
A customer of a local dealer replaced his Atma-sphere MA-1s with Convergent Audio amps and instantly regretted this decision. The CA amps werent bad, the MA-1s were just much better, he felt, on his speakers. I own MA-1s and need to send my Quads (63s) in for a refurb. but am using the amps with dynamic speakers at present. |
@miko71 , This is true for the smaller speakers. The 8 foots speakers will make bass down to 40 Hz fine even at volume but subwoofers do better and using a high pass filter on the Sound Labs lowers distortion quite a bit by preventing the diaphragms from taking long excursions. If you like rock and loud jazz IMHO subwoofers are mandatory but then again this is true of most dynamic speakers. Pinotnoir, The only tube amps I would use on the Sound Labs are the Atma-Sphere MA1 or MA2. The MA2 seems to be a favorite. I have no heard one but Roger West relates many Sound Lab owners prefer this amp. They are vastly different to other tube amplifiers. They are also more powerful into the Sound Labs than their power ratings suggest. I think you can safely assume they are equivalent to a solid state amp of twice the power. Not every solid state amp will drive them well. I know for a fact the Parasound JC1 will drive them and I suspect other high powered class A amps will also. The JC1s sound more like a tube amp than a solid state amp. I am a huge John Curl fan. |
