Review: Classe Audio 70 Amplifier

Fascinating. Maybe I should've held onto mine and sold it for the big bux after everybody reads this thread... :-)

As I alluded to above, it had been a long time since I'd had a solid-state amp in here, and I was curious what might be done today in the way of a moderately-priced one, along the Seventy's general lines. Well, I solved that by going and buying a McCormack DNA-125 from a fellow 'Goner not too long ago. Compact, inexpensive, well-reviewed, power MOSFET's, cult-like following - but almost double the wattage.

This amp was a very pleasant surprise for me. In fact, it showed up some shortcomings with my VTL tube mono's that I ultimately traced to some failing tubes. It's good to have a SS amp around just as a point of reference for consistent performance. I would rate this McCormack much more highly than my Seventy. It's not perfect, but I find it easily more "musical" and "involving" - and just plain competent - than the older Classe. Some of you guys should try to hear one (well warmed-up).

However, after flirting for a few days, when I finally got my tube situation straightened out it became clear that the silicon-hearted amp was never going to tempt me away from my fire bottles. I find it interesting Scanton that you feel tubes always sound rolled-off up top - I've never heard a sub-mega-buck SS amp that sounded as open through the treble to me as an above-entry-level tube amp usually does. It's also interesting that the oft-expressed sentiments about 'musicality' and 'involvement' are being turned by you against tubes, because that's usually exactly what people who love tubes argue to those SS'ers who complain about specs and bass...

Anyway, to answer your question about how long it originally took me to "adjust" to tube sound in my system? - About 30 minutes..."honest"!

Well this week end was most interesting to say the least. Several people showed to audition the Acoustat Model 2 speakers.

Not wanting to dismantle my main system for this audition I used the Classe 70 Amp, Marsh P 2000 PreAmp and the Classe CDP .5 CD Player. Used the standard factory supplied power cords with each unit. The interconnects were the old Golden-ens(remember those?) for PreAmp to Power Amp. CD interconnects to Pre Amp were just standard Sony issue I had here,never used. Speaker wire was the Original Monster Cable from about 1982 or so. Basically just to show the Acoustats worked for the prospective buyer. Had the Acoustat Model 2 plugged in for about 3 days to help stabilize them. Usually takes 7 days for the transformers to really come on line.

What ensued was quite remarkable, even as jaded as I am, was taken aback. First I did not expect the Classe 70 to be really able to handle the Acoustat load. Acoustats have a widely varying ohm load and are quite reactive. Takes a very special amp to handle Acoustats. Before the first customer arrived fired up this system and was totally amazed at the ease the Classe 70 was driving the venerable Acoustats and at very loud levels at that. Oh well perhaps a little prejudice here, the real test is the customer response to this system.

First gentleman to arrive had brought his own amp and speaker cables to audition with the Acoustats. After hearing what I was playing, decided it was a moot point to bring in his amp. Which was far costlier and very high end to boot. I left him to his own devices as he had brought many CDs he wanted to evaluate on the Acoustats. He spent well over two hours here. He just couldn't get over the sonic signature he had been hearing. Kept saying seamless,liquid and detail he had not heard before. And was totally floored when he as informed no special cable or interconnects and 22 year old monster cable. He had admitted visting several high end stores locally and had heard nothing that came even close to this.

Next person came over with his amp and once again decided just to audition the CDs he brought along. His amp was an Audio Research D120 recenlty back from AR service. The result was very much the same as with the first person,totally amazed at what he had heard. I think his wife opposed the Acoustats due to their size and room decor. Who knows I think he will be back.

Third person over was a gentleman from a very well respected name in High End Audio, although I did not know this until he handed me his card at the end of the day. This was not the usual audition, he really knew his way around high end gear. Totally examined the entire system, ask what power cords, interconnects, speaker wire, any mods to the Classe or Marsh or Classe CD Player, told him all stock out of the box units. He made the comment that he would not have belived the Classe 70 could power the Acoustats let alone produce the signature that it produced.And noted that the Classe heat sinks were quite warm but one could leave there hand there without discomfort. He as well had brought a lot of CDs to audition so I left him to indulge. As a last request he wanted me to open remove the top of the Classe 70 amp so he could have a look inside. Oh well what the hell, complied with his wish. Remove the top, he examined so closely that i thought he was going to climb inside. You're right he said, factory stock, no mods. This is a most remarkable system here. I almost do not believe what I am hearing. Plus the stock cords,cables, and speaker wire! He informed me who he was and that this was one of the top five systems he had ever heard-period! This coming from who he was totally stunned me. Lets face it I literally threw this together just to audition the Acoustat Model 2 I wanted sell.

So here's the dilemma is the Classe 70 really that good or is it the combination of components? This is the first time I have put the Classe 70 to the Acoustat Model 2 and must say it does sound fabulous, much better than I had ever thought it would. I wasn't interested in selling the entire system, so that may have been the reason they haven't sold as of yet.

At this point may very well keep the system. To say the least a most interesting week end. The Classe 70 performed far above my expectations, and I already like the Classe 70 very much indeed, but this has been a total eye opener for me.

Guess I owned the wrong speakers (hell, the wrong system) to go with my Seventy...enjoy your 'new' system! ;^)

Seriously, I still find it impossible to beleive that the amp I knew could make sound to draw such raves - *unless* something was wrong with mine unbeknownst to me (it certainly didn't seem so ; the sound seemed about appropriate to what the amp was [better than the NAD it replaced], it looked beautiful inside, and it never gave me a lick of trouble otherwise), *and* we accept the notion that a properly-functioning Seventy *really is* capable of top-rank sound with no excuses (a proposition I would find dubious even if I had never owned one, being as there's no apparent reason for suspecting it to be true). System synergy can trump a lot of things in some areas, such as tonal balance or soundstaging, but IMO it's tough to give a lot of credence to the implication that system synergy could grant superior resolution, purity, imaging, or harmonic structure (as examples of other areas where I thought the Seventy wasn't strongest) to a group of components whose weaker links are known to fall short in those respects when heard in other contexts. And especially when the partnering speaker in question should be stressing the amp much more than the Thiel CS2.2's I used mine with (a pretty kind 4 ohm load of average sensitivity, and not a speaker reputed to wildly prefer the tubes which beat out my Seventy).

I'm curious: Was your independent opinion of the audition combo quite as high as your prospective buyers'? Does the Seventy beat out your own reference amp(s) in this application? If you leave the speakers and amp set up as is but swap out 'better' wires and sources, does the sound not improve? The only scenario I can think of here is that the amp/speaker cable/speaker combination, taken as a sub-system, represents a fortuitously copacetic mixture of electrical properties, that the front-end balance perfectly complements that of the back-end, and that you have the speakers perfectly set up in a room nearly ideal for them. Either that, or your customers can't hear. Or the Seventy, against all odds and reason, is one of the very greatest amps ever made...

I am reporting what the prospective buyers were saying of what they heard. My main amazement was that the Classe 70 could handle and drive the Acoustats-period-let alone drive them so very well indeed. I have yet to use one of my Forte or Threshold Class Amps,nor have I tried other power cords or interconnects. The room is not very ideal carpet on floor no drapes or such on the walls. I would not call it an ideal room at all.

Have two other appointments this week end to audition the Acoustats. So we will see what ensues. Although I have one call back now from one of the first three. Wanting the entire system.

I have spoken with a few people whose opinions I value and have been in high end as long as I have since 1957, actually before high end. It is their considered opinion, that the Marsh PreAmp, and Classe CDP .5 has a lot to do with the sonic signature, both are dual mono operating in class A output.

I haven't listen to the system since Sunday night and won't listen to it again till Saturday when the prospective buyers arrive to audition the Acoustats. We will see once the Acoustats have had more that 7 days to season in.

I just picked up my second Classe Seventy, and it has some differences between it and my first one.

The serial numbers of the two units are not close at all.

They are both stock, but one has blue power supply caps, and the other has red ones. One has Motorola output devices and the other has Toshiba. The values of the resistors in the output stage are also slightly different.

I will take a closer look later on and post more details on the variations between what appears to be an early and later model.