Problem with preamp volume control

I suspect that statement is predicated on typical combinations of preamp gain, source output level, and speaker sensitivity, while also taking into account that providing the amp with unbalanced signals will result (everything else being equal) in less volume than if the amp is provided with balanced signals.

In this case, however, the gain of your preamp (line stage + phono stage) is **much** higher than is typical for use with a high output cartridge, and so I can’t envision any reason to pay attention to that statement.

Best regards,
-- Al

P.S. to my previous post: If you are using RCA-to-XLR cables, rather than adapters, and you ultimately find it necessary to purchase Rothwell attenuators, my suggestion would be to replace the cables with RCA-to-RCA cables and use them in conjunction with inexpensive RCA-to-XLR adapters, such as this one.  But hopefully (and I suspect probably) the amp's adjustable gain provisions will do the trick.

Also, regarding ...

He said that an attenuator is very feasible in the line stage but not in the phono stage.

To be sure it’s clear, the attenuators would not be used in either the line stage or the phono stage. They would be used at the inputs of the amp, as I described above.

Best regards,
-- Al

The line stage gain is 27 Db
The phono stage is listed as:
High gain 54 Db
Low gain 40 Db

Not sure what to make of that, RV. The description of the PV11 at the CJ website, the manual for the PV11 that I found online, and Stereophile’s measurements all indicate the gains that I cited in my initial post, or very close to them (47 db phono stage gain; 18 db line stage gain).

In any event, though, if your preamp is in fact providing 40 db of gain in its phono stage and 27 db in its line stage (27 db being **very** high for a line stage, but not atypical of many CJ designs), the total of those two numbers and the total of the numbers I cited constitute very similar overall gains. But if perchance your preamp is providing 54 db of gain in its phono stage, that is something that is probably in need of correction, IMO, given that a high output cartridge is being used.

But regarding your amp, as Antinn pointed out it provides three different gain settings, namely 9.2, 17, and 23 db. If you are not doing so already I would suggest trying the 9.2 db setting, even though the website description suggests using one of the other two settings when single-ended inputs are used.

Regarding attaching an attenuator, as you can infer from the photo provided at the Rothwell site you would purchase two of them and simply insert one into each of the RCA-to-XLR adapters you are presumably using at the amp inputs, instead of plugging the interconnect cables into the adapters. You would then plug the interconnect cables into the attenuators. Very simple.

Best regards,
-- Al

You can install the attenuators on the phono input or on the amp input depending on what else plugs into the preamp.

I would not install any such attenuator on the phono input in a case such as this, where a high output cartridge is being used. The resultant loading of the cartridge will be very non-optimal.

Also, I recall that some time ago a member here measured the impedances (i.e., the series and shunt resistances) of Harrison labs attenuators, and the numbers were vastly lower than those of the Rothwells, and are likely to be problematical in many home (non-pro) audio applications. Especially when driven by many and perhaps most tube preamps.

Regards,
-- Al

Hi RV,

The root cause of the issue is that like many Conrad Johnson preamps yours has higher gain than most. Although many other CJ models have considerably higher gain than even yours. The PV-11 specs being 47 db for the moving magnet/high output moving coil phono stage and 18 db for the line stage, those numbers closely corresponding to Stereophile’s measurements.

My suggestion is that you insert Rothwell attenuators into the input jacks of your power amp. They come in 10 db, 15 db, and 20 db versions. I suspect that the 10 db version would result in volume control settings roughly in the area of 11:30 on the dial, and the 15 db version would result in settings in the area of 1:00. I would choose one of those two, rather than the 20 db version which I suppose might increase the possibility of unwanted side-effects.

Over the years here some members have reported compromises to dynamics or other unwanted side-effects using Rothwell attenuators, while others have had very positive experiences with them (including me in a past incarnation of my system, using the 10 db version). I suspect that some of the reasons for that discrepancy involve impedance considerations specific to the particular system. I wouldn’t want to speculate as to whether or not that would be an issue in your particular case, but given the cost of these attenuators it seems to me to be a very reasonable gamble.

Finally, I would strongly recommend against any other brand of inline attenuator, as I know that some of the others have impedances that are too low to be suitable for use in many and perhaps most consumer-oriented/non-pro applications.

Best regards,
-- Al