2. amps-preamps
  3. 1140360469

Preamp Connections - Balanced vs. RCA

I didn't know quite where to put this, so I figured this would be a good spot.

I just replaced my old preamp with a Pass X1, which has the choice of either balanced or single ended connections from the source components. My old preamp was RCA only. So right now I'm using my existing RCA ICs to get to the X1.

I'd like to consider trying some balanced interconnects (rumour has it that the X1 runs optimally with balanced connections), but I'm worried about the voltage delivered to the preamp. My sources (like my D/A) have the standard nominal 2 volts out from RCA and - what is it? - 4 volts for balanced. The thing is that X1, even with the gain set to 4 dB, seems to amplify the signal a lot faster than my old preamp. I'm only using a small portion of the volume control to get the needed volume. If I go to a balanced in on the X1 will that range now be even less since there's 4 volts at the input instead of 2?
tonyptony
mikesinger
572 posts
 
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.
tonyptony OP
617 posts
 
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.
tonyptony OP
617 posts
 
"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.
mikesinger
572 posts
 
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)...
rgodin
85 posts
 
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
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