Out with the old, in with the new

My first amplifier I bought in 1979, a Technics SUV-6. I'd saved up for a set of B&W DM7s eventually decided to get a second hand pair of DM6s. So then I needed an amp. Mr Robinson, the Bowers & Wilkins salesman (the retail shop was I think already a separate business from the speaker division by then) suggested the SUV-6 and so that's how I ended up with it - along with a Technics SL150 turntable and an SME 3009 Series II tonearm. The only other change in my setup until this week was a Linn (ex demo from Grahams HiFi in Camden) with an Ittok which replaced the SL150+SME in 1987.  

That is until last week, when my trusty SUV-6 finally gave up the ghost. It's fixable I think but the input switch has been getting more and more temperamental for several years and last week it decided to stop working altogether.

Knowing I wasn't going to have time to fix it for a while, I decided to take the plunge and buy a new amp.  I did some estimates and figured for the GBP 200 I paid in 1979, with inflation and the exchange rate, I should be spending between $1,200 and $1,600.

So instead I looked for the cheapest reasonably well reviewed integrated solid state amp I could find.  And so plumped for this (bottom of the pile in the pic), the Yamaha A-S500, a B-stock factory reconditioned unit for $319. And I was in for a bit of a surprise.

I had always rather poo-poohed the notion that amps could really do much to alter the sound. After all it's simple a case of taking a signal and making it louder. The scope for 'error' was far lower than in the engineering of a turntable or a cartridge. And speakers, clearly have a huge impact.

And was I wrong!  The A-S500 is rated as 85W into 4 ohms, compared to SUV-6's 70W, but it's much wimpier. But that's only the beginning. It's completely lacking in bass compared to the SUV-6. On my Phase IV's there's almost nothing there below about 150Hz. The 31Hz open B notes in Becker's "11 Track of Whack"? The bass player appears to have taken the day off.

But suddenly the DM6s sound a bit more like a modern speaker - brighter and without the smiley face response curve. I haven't done any tests yet, but I suspect the new amp has flattened out the DM6 curve.

And that's is a bit of a problem since it suggest that the SUV-6 was as much a part of the smiley face as the speakers - and I used it do calibrate the Phase IVs and build the crossovers. Ugh!

On the plus side, I can always go back to individual driver testing and redesign the  crossovers; which I will undoubtedly have to do if I want to continue to use them with the A-S500. But if I repair the SUV-6 then I'll need the current crossovers. Not to mention that I am still thinking of getting a cheap tube amp at some point, and it's not clear how that will change the picture. And of course I've got the Phase Vs on the drawing board which I'll start building when...

I may have to build external crossovers that are matched to a speaker amplifier pairing.

Damn! Lots of work, lots of variables, not enough time (or money).