[rjb5191]

Hi I'm interested in either of these amps and was interested in hearing your opinions on them.  I particularly interested in the lineage of the amps and how they changed through the years.  Through hearsay I've heard that that the SM-70's were pure class A but are now high bias class AB.  Does anyone have any light to shed?

thanks.

[Ericus Rex]

The first iteration of the SM70 was pure class A and sounded marvelous for such an inexpensive amp.  I understand that people complained about how hot the amp ran (necessary evil for pure class A) and the designer rebiased the circuit and all that wonderful magic was lost.  The early ones have a distinct look to them.  Some would say gaudy, but those are the ones you want to look for.  Ask the seller if it runs hot...too hot to keep your hand on the top cover for more than a few seconds.

I have no experience with the 100s.

[CactusBob]

I have one of the older SM70's apparently that I bought used and love it. It's driving my Altec 19's and it sounds better then any of the other amps I've used. Nothing high-end just receivers and mid-fi power amps etc. I also like the sound better than my tube mono-blocks. The little Class A amp has more punch and dynamics. I removed the top panel to keep it cooler, but it runs cooler than my tube amps and in AZ that's a big plus. I thought about buying a new one to bridge them perhaps but didn't hear about the AB thing. That's diappointing. Here's mine.

[Ericus Rex]

I have one of the older SM70's apparently that I bought used and love it. It's driving my Altec 19's and it sounds better then any of the other amps I've used. Nothing high-end just receivers and mid-fi power amps etc. I also like the sound better than my tube mono-blocks. The little Class A amp has more punch and dynamics. I removed the top panel to keep it cooler, but it runs cooler than my tube amps and in AZ that's a big plus. I thought about buying a new one to bridge them perhaps but didn't hear about the AB thing. That's diappointing. Here's mine.

That's it but I seem to recall them having a very fancy gold pair of handles on the front which yours doesn't have.  I also remember the newer AB ones looking just like the Class A ones at first so I wouldn't just go by the "Pure Class A" on the faceplate when looking for one.  Be sure it runs real hot...if you want one of the true Class A ones, of course.

[Goosepond]

I bought these here on AC a few months ago:

http://www.audiocircle.com/index.php?topic=114889.msg1199743#msg1199743

I was looking to try some SS monos. They are nice little amps and although they do run hot, I would say they are  not objectionably so.

Gene

[rjb5191]

Thanks so far guys; this has been very informative.  Sounds like it will be tough to get one's hands on one of the older "Pure class A" models.