Conrad Johnson Owners.com

Hi! I recently purchased a vintage PV8 preamp and a MF2200 power amp, but I have an issue: I can not put the volumne in the preamp over 25% because it seems to blow the amplifier, too loud... Is this right or there is a problem with the preamp?
The speakers I am using is a pair of Energy Veritas 2.8.

Hola Paco...ya le escribí a Efrain. Con un divisor PI, te lo puedo hacer. Necesito que me traigás el pre y el amp...con todo gusto te lo fabrico.
Saludos,
Roberto.

Hello Paco... I just wrote to Efrain. Nothing is wrong with your preamp or your amp. The problem is that your PV-8 puts a lot of output voltage and your amp sensitivity is very low. With a PI attenuator, it can be done. I need you to bring both units to me. With much pleasure I can do it easily.
With the best,
Roberto.

Roberto, very thankfull for your fast response and your fastest way to manage the modification on my PV8, the PI atenuator works very fine!
And thanks too for the change of the leaking capacitors an the advice on the rectificator diodes (I'll change them very soon).
The sond is great (as allways with CJ).
I'm very pleased to meet you, such a fine person.
Thank you very much!!!!!

Hola Paco,
Very nice meeting you too. Now your beloved PV-8 is back with the greatest sound of C-J. I´m glad that you are that cheerful and satisfied! Conrad Johnson sounds right!

Happy listening,
Roberto.

HI All,

Will using an in-line attenuator have the same results?

I have a PV8 connected to a Premiere 11 and I can barely turn the volume dial. My speakers are near 100db Sensitive.

Thanks!

I used to recommend inline attenuators for this purpose, but after more experience with them, I am negative about their effect. You can try them. I have a pair of RCA compatible from Rothwell (I think), but I consider them to darken the sound, and to veil detail. YMMV, of course.

Hola mstrshikadance,

Two things might increase the volume. The Cartridge that you are using should have less than 1mV of output. If your cartridge has more output, then there is nothing that could bring down the volume, unless you re-design the phono preamp. That is a very difficult task. 0.6mV would be ideal the cartridge output.

There are similar tubes with less sensitivity, you might use them with the same specs of the tubes with less volume. You might get some decrease of volume. Just do some tube rolling and let your ears decide.

The problem is really the 100 dB/W/m speaker efficiency.

Of course Roberto is right that going to a LOMC cartridge will reduce the output.

The PV8’s gain by itself is relatively low, no? I don’t have one in front of me to look, but I’m thinking it was in the 44 to 48 dB range since it was set up for 47 kOhm MM cartridges. I had a PV 8 and used cartridges in the range of 3 to 5 mV at 5 cps. But I always had speakers in the mid 80’s efficiency range.

System matching …

If you go to an LOMC, you’ll have the issue of cartridge loading since the PV8 is fixed at 47 kOhm. Most LOMCs would like to be looking at 100 to 1000 Ohms.

And, of course, the phono cartridge output has no impact on the line level sources.

The line stage gain of the PV8 is 31 dB. That is VERY HIGH, even for Conrad Johnson.

Are you running the Premier 11 in triode mode? That might help some.

But your speakers and preamp really aren’t a good match if your goal is to listen at modest levels.

AnotherJohnson wrote: ↑Mon Nov 28, 2022 6:35 pm
The PV8’s gain by itself is relatively low, no? I don’t have one in front of me to look, but I’m thinking it was in the 44 to 48 dB range since it was set up for 47 kOhm MM cartridges. I had a PV 8 and used cartridges in the range of 3 to 5 mV at 5 cps. But I always had speakers in the mid 80’s efficiency range.

I was referring to the phono gain.

The specs say 47 dB.

So … that’s plenty for MM cartridges, and on top of the 31 dB, way more than will be good for most people with 100 dB/W/m speakers.

Sigh ….

For my PV8, I'm using a MM cartridge with 3.6mV; my speakers have 83 db efficiency. It's a nice match-- for volume in my small room that is plenty loud, but not earsplitting, my volume control is between 10-11. My amp is Pass XA-25, nominally 25W/chan, but Stereophile measured 80 wpc at stated distortion.

Curious about advice from Roberto about changing out "rectificator diodes". What is the problem? Where are thet located and change to what?

83 dB/W/m should work quite nicely. Glad to hear that you like it.