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Emlyn wrote: »

Although I haven't asked Benchmark it appears the AHB2 is a fully balanced differential amp design, meaning not going to run Polk L800 speakers. The design is what makes it have such a good S/N ratio.

Yes it is a fully balanced differential amp. Too bad it's not a good match for the L800's. That would have been awesome!
As far as the design goes I believe it was an 8yr project with THX & Benchmark engineers. All I can say is that they nailed it!!

I think Jesse made some recommendations in my thread about my tube stereo console as to how to clean those. I’d go check it out.

From https://forum.polkaudio.com/discussion/177816/today-i-stole-me-a-piece-of-gear/p1

Emlyn wrote: »

I understand the number of gain detents (clicks) to be about the same with the T/5X and the S/812. Around 40 if I remember right but mine are usually somewhere between one quarter and one third only. I remember I had to drop the gain on mine quite a bit during the break in period which was a bit annoying when the system would sound slightly off every week for the first three months.

It is a nice feature to have on the AHB2 to provide for different gain and a professional recording studio focused feature. Parasound tends to have a continuous gain knob on their two channel amps with the best setting at full on. That's kind of a relic from their original custom installer focus.

You are correct about the Parasound, the A21+ has gain settings for both channels. I found that the highest setting was what I preferred. The AHB2 has 3 settings (low, med, hi). Benchmark recommends the low setting for RCA, med for XLR & hi for upstream pro gear. Talking with Rory at Benchmark he recommended the med setting for the best match with my pre & AVR. He also said to experiment with all 3 to see what worked best. The recommended med setting was spot on.
I know 3 clicks of volume decrease on a REL might seem like a lot but that decrease really dialed it in perfectly. I don't run it hot at all, just enough to fill in the bottom end without drawing attention to it's self.

I have inherrited my grandparent's old Philco 37-650 from 1937. It has sat for many years unused. My aunt passed away in August, the house is being emptied to sell and I couldn't see this radio going to waste. It was dirty as he-double-toothpick and I was amazed how it cleaned up with vacuuming and some very dilute mild dishsoap. The cabinet need a little work and I'm hoping I can bend Jesse's ear for some advice.

I am not sure if it works yet and am refraining from trying to power it up without a dim-bulb tester. I have also read that the caps should be replaced before even trying.




I am also inherriting my dad's old Philco 37-60, also from 1937. He has had this since he was a young man in Fells Point, dabbling in electronics. He restored it a number of years ago. Before he passed away in November (tough year), he told me that it still works.



Unfortunately, my dad gave away his Hickok tube tester and caddy of tubes .