Phono stage direct to amp?
Looks like your cartridge has a rated output of 3 millivolts (mv) under the usual test conditions (1kHz, 5cm/sec). Your phono stage has gain which is selectable to either 40db or 50db. 50db corresponds to a voltage gain of about 300, which would result in 900mv into the power amplifier. That's a bit light for many power amps, but is ok with some. Which one are you using? Regards, -- Al |
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 |
