Phono stage direct to amp?

Al,

The amp is the LR channels of a Proceed Amp 3. I too had thought about the volume control, and what seems to be an inconsistency with a truly passive pass-through. I suppose it could be acting only as an attenuator.

I got into vinyl again as a fluke, having given away my AR turntable and LPs years ago. But a couple of years ago, a close friend offered to give me his AR turntable with Shure V15 II cartridge, and I accepted. A local expert said it wasn't worth restoration for reasons I didn't ask about. I thought to buy an inexpensive new turntable and arm, but the dealer had been given a Thorens TD 160 BC II with a SME II arm and Ortofon SME 30H cartridge by a local who had switched his whole house to digital. They had checked out the turntable and offered it to me for $200 or $300. I bought a CIA phono stage and power supply from someone on Audiogon. I was amazed when I first played a recording; it actually sounded great, with nice wide and deep soundstage, good transparency and detail, very like an excellent SACD -- my bias. My cousin returned all my old LPs that I had given him. I felt like the pig who fell in it and came up smelling like a rose.

db

According to the manual, the Proceed Amp 2 and 3 require 2.4v to reach the full 250 watts/channel @ 4 ohms in balanced mode. I use the LR channels of an Amp 3 to drive KEF Reference 104/2 speakers that have an efficiency of 92 dB, and are high-passed at 80 Hz; a Velodyne HGS-15 controlled by an SMS-1 handles LF duty. The 104/2s are biwired. I assume that at even very high acoustic levels very little of the available 250 watts is drawn.

Al's determination is that the phono stage would provide only about a third of the voltage needed for full power, but would that matter for this application?

db

DB, I took a look at the Integra 9.9 manual, with inconclusive results. There is no indication that "direct mode," which I think is what you would be using, disables the volume control, which is good. All it says beyond that, though, is that there is "minimal processing" in that mode. My intuitive guess is that there would be one or more active gain stages still in the signal path, though, which would resolve any doubts about gains and levels, but at the expense of the possible sonic effects of those stages.

If it does provide just passive attenuation in that mode (or some other mode), though, I suspect that you'll be ok, given your 92db speakers and the high-pass filtering which precedes the amplifier.

Just as a point of information, 0.9 volts is about 8.5 db less than 2.4 volts, which would essentially convert your 250W amplifier into a 35W amplifier.

Regards,
-- Al

DB, just noticed that you had said that the 2.4 volt sensitivity is in balanced mode, which I confirmed in the Proceed manual. Am I mistaken in thinking that the high-pass outputs of the SMS-1 have to be taken from unbalanced rca connectors, in which case the amp sensitivity is 1.2 volts rather than 2.4 volts?

If you will be connecting the SMS-1 to the amp single-ended, everything is pretty much a non-issue except for the possible sonic effects of the Integra.

Regards,
-- Al

Al,

1. Another poster at Audiogon who seems much more serious about analog than me (my wife would say I) reports unsullied audio when taking his analog input through a 9.9 pass-through.

2. I use the balanced sub output from the PDSD to the balanced input of the SMS-1 and the balanced output of the SMS-1 to the balanced input of the HGS-15. From the PDF manual, I see the 9.9 has a balanced sub output as well. I suspect even 35 watts/channel will drive the high-passed 104/2s very well and still provide lots of headroom.

Thanks for all your help. A more pressing matter is that the audio/video sync is off by seconds whether the signal comes from the PS3-80 or the HD-DVR. It happened last night after I had monkeyed with the audio setup on the PS3-80, lost the audio by setting output to be digital optical and regained audio by setting the output back to HDMI. It was late so I didn't recheck how I have it hooked up, but I know the PDSD has no HDMI input. But the sync problem was with both the player and the satellite inputs. I couldn't find audio sync in the manual for the Sony VPL-50 projector last night. I'll look again this morning.

db