Preamp Connections - Balanced vs. RCA

http://www.tweakaudio.com/Ultimate%20Attenuators.html

You can sometimes find them here used for $250 to $300. That is how I found mine.

"i was looking at the x-1 and was advised i would have to reduce the voltage of my dac if i went with it"

Mike, I just got off the phone with Pass. The indicate the inputs of the X1 (RCA and XLR) are indeed buffered and should not require any change in volume depending on which input is used.

"I used a pair of ultimate attenuators between my source and the X2.5 to drop the source gain, for an addition $300"

Rick, do you have a link to these attenuators? I too feel I'm getting too much overall gain between the X1 and my amp, but the only investigation I've done so far had been for the Rothwells, and reports on AA suggest they effect the sound. I didn't realize the X2.5 has such large steps between settings. The X1 is about 1 dB per step, but it and my amp (FetValve 550EXR) still add up to an overall gain so that I can only get through about 1/3 of the total travel before I hit a point that I would not "normally" exceed.

I had an X2.5, which uses a similar design to the X1. Even at the lowest gain settings I was getting too much volume. I used a pair of ultimate attenuators between my source and the X2.5 to drop the source gain, for an addition $300.

Also, I found that the 3 dB steps on the volume control were spaced too far apart. I was always stuck between too loud and too soft.

I thought the sound of the X2.5 was very good, but the lack of a volume control with small incremental steps just got to me. I replaced it with a Placette Active that had a dual range volume control, each with 127 steps. I like the Placette much better and I can always get the volume exactly where I want it.

Rick

you are correct..i put a "if" in my statment.....i was looking at the x-1 and was advised i would have to reduce the voltage of my dac if i went with it..

depending on the system and where you like to have your volume (7 o'clock, 10 o'clock, 1'clock).... if the input sensitivity of the pre is too high is to high and the gain selection wont go low enough....you can reduce the output of your dac and it isnt that hard to do (generaly a couple resistors etc...)

are you sure the output voltage of your dac is 4 volts ???? most sources will have double the voltage of the rca, but not always (electrocompinet dac for instance is 3.3v)...

"i have heard of this with pass pre-amps...if the volume is too high and you cant adjust the "

It's a Boelen modified DSP-7000 Mk.III. I have no desire to change it. You're comment confuses me relative to Nsgarch's. Do you have info that indicates Pass preamps do NOT normalize the inputs? If so that makes using balanced a non-starter for me. I'm thinking I'll call Pass tomorrow and find out for sure.

Thanks Nsgarch. That makes a lot of sense. I suspect you're right about the inputs being "normalized" RCA Vs. XLR. The X1 does have a gain selection - either 4 or 14 dB. But in the case of 4 dB (which is where I keep it) the midpoint delivers enough of a signal to the amp so that it's plenty loud. I may pick up a couple of used balanced ICs here on the 'gon and try them out.

i have heard of this with pass pre-amps...if the volume is too high and you cant adjust the overall gain, then you might be able to reduce the voltage output from your dac ( make it 1.4 volts instead of 4.....) what kind of dac do you have ?

btw, running balanced makes a really big difference.

The gain should be "output-adjusted" within the preamp so you can mix se and bal inputs without having to countinually adjust the volume. Using balanced ICs is especially beneficial sonically with DACs for some reason, so if your DAC has XLR outputs, you should try using them and see what you think.

I don't know much about Pass equipment, but based on its reputation, I wouldn't be surprised if there's an internal (or external) global gain adjustment so that you can normall use the center sector of the volume control.