You've got impedance mismatch problems, when you are placing that resistive attennuator in the line. This is typical with passive preamps, and it is always a struggle to get them to be anywhere near acceptable. The way out of this, if you want to stay with a passive pre, is to use a transformer-based passive, that provides better impedance matching characteristics, because of the nature of it's design. Since a transformer has separate windings on input and output, the impedance can be better matched. All of these things that you are complaining about are typical of resistive-based passive preamps. Check out the Bent Audio website for further information on this subject. They sound cleaner, and work better. Much more beneficial all around. They can be gotten even as a kit, if you are working within a budget.
Gain and Rothwell attenuators
I have a Rega planet 2000, Cary slp-50a, and linn LK-85 amp. When I first got the cary I couldn't turn the volume up past the 8 o'clock position! That was about as loud as I could stand. I put in some Rothwell attenuators (-10db) and now I'm at about 10 o'clock with the same result. Problem is is that the Rothwell attenuators dramatically alter the sound. Right now they are between the cd player and pre-amp. I tried them between the pre and power amp and the music sounded strangled. When I take them off completely things open up but seem uneven and I start getting different L/R signal strength through the speakers at lower volumes, with some cds becoming unplayable because of this. I haven't seen much written about attenuation or any other way to solve this problem. Are there other, more neutral ways to achieve this or has anyone come across another posting on this issue? Thanks and happy holidays.
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Parts quailty of the resistor attenuator elements may be compromised. If you know the required values then you might experience better sonic performance by replacing them with Holco, Caddock, or Vishay's avalable from Michael Percy Audio. Use a quality silver bearing solder such as WBT. http://www.percyaudio.com |
their shunt volume attenuator involves less signal degradation than typical series attenuators due to reduced series resistance in the signal path. It is possibly a simple pi-ladder design with two low-level elements in series & the adjustable element in parallel to signal ground. I assume that this design also reduces stage-gain or they wouldn't have recommended it? Or if not then at least linearity is improved such that the aforementioned issues are resolved. |
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