Superphon amp

[SirPaulGerman]

I got lucky and was able to get this Superphon DM 200 for $125, there not much information out there about the amp
Designer was Stan Warren former PS audio
The amp sounds amazing, and is working fine, it came out in 1988

Transistors are 2SD424 NPN/ 2SB554 Toshiba
40000MD for storage, wow
rated to 2 ohms
125 watts
signal to noise ratio 98DB
THD < 0.01 %
IMD < 0.05 %

The amp runs very hot, hotter than a Hafler XL-280

Can someone comment on the design and specs ?

Some other info from another user

"It’s probably just shy of 35 years ago that I asked the same question of Stan Warren (cofounder of PS Audio) as the Consumer Electronics Show in Las Vegas. Stan has a reputation for being a purist and minimalist who selects the components he uses through double-blind listening tests. I was a newly degreed EE at the time -- and was trying to learn from one of the gurus. We had met previously as PS Audio used to be in my college town of San Luis Obispo CA.

Stan and I were discussing the design aspects of his new Superphon DM-200 power amplifier (which I ended up purchasing from him at the show). The DM-200 was one of his products which used tantalum capacitors throughout the signal path. It and his "Revelation" preamps were very highly regarded "budget" preamps at the time (and may well still be).

Stan explained at the time that from his experimentation, solid dielectric capacitors (tantalum, silver mica) consistently provided better sonic performance when used in the signal path. I recall his comment that the capacitors in his designs remain powered up at all times and are biased in the middle of their operating voltage range. He found that keeping the capacitors charged provided both the best sound and greatest longevity. (I'm not sure if the front end of the power amplifier remains at idle -- probably not.)

Not sure what the current thinking is in this regard but those tantalum capacitors may have been very carefully considered by the designer. If you're changing out the capacitors you might want to carefully evaluate the before and after sonics."

 

[DanielT]

Cool amp. Congratulations, if it works as it should, that is.

The more intricate technical details can be answered by someone with more knowledge, but I have a few questions myself.
Do you have a infrared thermometer so you can measure how hot it is?

A 35-year-old amplifier, which may have been used a lot, which also gets really hot then it must have worn hard on the electronics over the decades?
Whether and how parts should be replaced is for someone else to answer. But okay, it works well, then if it ain't broke, don't fix it fits as the saying goes. Or?

 

[SirPaulGerman]

Here are the schematics

 

[JeffS7444]

No surprise, it looks exactly like vintage PS Audio. I see no tantalum capacitors, just aluminum electrolytic, and polystyrene types. Did it always run hot? I don't recall his earlier designs doing so.