Martin Angus

New Member
First Post...(in this forum)

I recently acquired a couple of Vintage McIntosh units at a steal price (since the seller could not confirm functionality). I gambled and looks like it was a good call. I bought an MC2105 power amp and the matching C28 pre-amp. After some cleaning (20 years of dust collection in storage), I powered up both with a Dim Bulb Tester that I built. The C28 was fine, the 2105 failed...blew fuses (needs output transistors). So the Amp is now being repaired leaving me impatiently fiddling with the C28.

I have another vintage unit that I bought new in 1982...Realistic (by Fostex) STA-2300 receiver, 120wpc 15-25k freq resp at .05% thd. I have always been impressed with the performance of this beauty...so I decided to isolate the built in STA pre-amp and compare it to the C28 both out-putting to the STA power amp section. I found it difficult to get a good impression of the differences due to the 5 min lag between re-hooking up cables, so I dug out my trusty old DJ mixer with cross fade capability. I split the source music to go to both pre-amp inputs, connected the mixer output to the STA power amp, and sent the two pre-amp outs to each side of the cross fade.

With all else being equal, (flat EQ, same volume, same vintage/available technology) output to amp then into Paradigm SE7-Mk3 speakers, the difference between the sound quality was very hard to discern. So I tried the headphone out from the mixer. All I can say is that the difference is very VERY subtle. The C28 seems to be slightly fuller sounding, bottom end richer though a tad less punchy.

Conclusion: I am as impressed as ever with the STA-2300 (selling for about $250-400 on the bay). It is a keeper for sure and severely overlooked by vintage buyers. I have to admit, I expected the C28 to blow its doors off, so maybe I need to recap? Perhaps the magic of the 2105/C28 combo with shed some light. Anyway, thought I'd share my A/B comparison with you good folks who are interested in vintage SS gear. Comments, insights welcome.
 
A few things come to mind......

Your mixer most likely has active circuits letting it act as a fader so you are really listening to it, good and bad.

The C28 dates to the late 60s early 70s and it's primary job was to be a preamp, that is amplify and equalize turntable or tape head signals up to line level, and add the tone circuit options. Not using the phono stage bypasses it's major strentgh.

Of coarse it is due for a recap.....it is over 30 years old assuming it was the last one built.......20 years for electrolytic caps is usually considered EOL.

Last relax and don't worry about quickly switching between units. Hook up a turntable and listen deeply for a few hours, then switch and listen some more.

Instant gratification is most often a dead end in high end audio......
 
I bought a STA-2300 new 37 years ago, it's in my office but for grins I hooked it up to my Klipshorns in place of my Rogue monoblocks, and, I was impressed, not better than the Rogues, but better than any other SS amp I've heard.
 
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