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Cable conundrum: Parasound A21 with RCA AND XLR

Ok, hope someone can give me a lesson. I recently aquired a Sonic Frontiers Line 2 preamp with both unbalanced and balanced outputs. First I hooked up my Audio Metallurgy GA-0 XLR's to my A21 amp, and I was not pleased with the sound. No depth, soundstage was choked. (gain was adjusted) I then connected my Synergistic Res RCA's to the outputs after disconnecting the XLR's. still not that pleased with what I thought was an upgrade.

In an accidental discovery, I reconnected the XLR's to the preamp WITHOUT ever disconnecting the RCA's. BLAMMO!! What sound I got! almost 5.1-like wide soundstage, reach-in depth, and the detail...let's just say i heard things from my CD's I never heard before.

So...how can this be? Both outputs from the preamp go to both inputs at the amp (balanced and unbalanced). Parasound tells me this is not a detriment to the amp. But I thought you could only use one or the other. Not both at the same time.
Any explanation?
evergrey
ja2austintx
64 posts
 
There is typically a 6 dB gain difference between balanced and unbalanced connections. In a balanced connection, the signal is differential -- e.g., when the positive leg increases by 1 volt, the negative leg decreases by 1 volt, and there is a net 2 volt differential signal. In an unbalanced connection, we only see one leg, or 1 volt of signal.

Twice the signal = 6 dB of added gain.
xti16
1,525 posts
 
That last point above is what I don't understand. I had to go down 2 notches on the volume control. Why did this happen? My CDP remains the same. Only the connection from preamp to amp changed. If someone could care to explain, it will be very helpful. Thanks in advance.
Pretty simple answer - Balanced output is in general twice the output in voltage (typically 4V vs 2V but that also depends on the manufacturer). Balanced was designed for professional setups where 50+ feet are needed. Also balanced has better noise rejection.

That being said I did a shootout about a year ago with Nordost Frey's and found the soundstage to be wider which I really liked but found the gain to be too much which I really hated. I went with the Rca's. My cd is a meridian G08 and my integrated is an Octave V70SE which both have a true balanced output and input. Just upgraded to the Tyr2 w/rca's.
milpai's avatar
milpai
2,489 posts
 
Ja2austintx/Xti16,
Thank You for explaining. Please note that my current CDP only has RCA and that is how it is connected to the TVC.
I was under the impression that for TVC, there is no real gain, as it does not have electricity input. I think a TVC only attenuates. I was aware that if I changed my CDP and the new one had 4.0V out instead of the current one's 2.2V, then I would stand to have a "gain" in my system.
Xti16 - for me the increased gain is a welcome change.
milpai's avatar
milpai
2,489 posts
 
Finally got a simplistic answer I was looking for, on the gain that I gained in my system using XLR connection:

The A21 gain is 6dB higher when the balanced connection is used. The output of your Promentheus is also 2x, or 6dB higher than unbalanced. Each "leg" or "phase" of the XLR is the same voltage as the RCA and two legs is 2x more which = 6dB. The same thing occurs at the XLR inputs of the A 21.
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