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Optimal gain structure of avr when used with proamp


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I have read some people turn up their pro amps to get the avr preamp signal high when using the pro amp with a subwoofer to prevent clipping. For examp, the subwoofer channel is -12 to +12. Normally somewhere near 0 works great but, with a pro amp should the sub be -7or-8? The pro amp uses balanced connectors for the sub and the avr uses a line level RCA. My understanding is that avrs use much lower output voltage and pro amps like a higher voltage.

See Sept 8th post for the technique to optimize gain structure of avr/pro amp: this will cut the post to the quick

Edited 9/8/2013

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I never really thought about it. On my AVR, I have something like -3 and on my Crown XLS-202 I have the gain knob at about 1/3. When listening via tube preamp, I set by turning the volume knob all the way up with the amp gain at -infinity, then slowly raise the amp gain while I adjust the gain control on the back of the preamp down until I have it where I can have both the volume on the preamp and the gain on the amp at thier highest settings without blowing the speaker up (with a careful eye on the clipping light). Then I lower the volume on the preamp and lower the gain on the amp to listening levels, about 1/3 and 1/3. It seems to give the best sound with lower output gain on the preamps.

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I have been safe so far but, I was read that the voltage in a balance connect is normally higher than an unbalanced one. This raised the question of the possiblity of clipping the pro amp due to a weak preamp signal althought the amp has plenty of power. I think I get what your ae doing mustang guy.[:)]

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Here is an excerpt from the AVS forum:

Mr. X

I currently have a Denon 4520 AVR with dual RCA sub-outs and am
running twin JTR S1's using their XLR input - (since thats the only
option). I noticed using this connection that the sub levels are very
poor and require higher trim setting to gain more output. I am
comparing this to my dual SVS SB13's that was connected prior. My
setting are much higher in the AVR, to get the same output.

Mr. X

guess my question is this, if I'm reading correctly, do I lose 6db
with using this type of connection(XLR-RCA)?
I just do not understand
why this would be the case? I was almost wondering if there was an
issue with my speakerpower amps, since the gain is maxed out to '0'
on the plate.

Mr. Y

Yes you are. Denon 4520 does not have balanced pre outs for
any channels and either you are using rca to xlr adaptor or rca to
xlr cable. In either case the subs are getting unbalanced signals.

This may more clearly state what I am trying to relay to the fourm members for dscussion. Several people concurrred on that forum of the 6 db loss and clipping issues.
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This is suggested as an optimal techique to match the avr and pro amp gain structure:

To begin, make sure all speakers are
disconnected from the amplifiers!
Also, make sure all
speaker-level settings in the AVR’s menu are set to max, including the subwoofer
output. Begin with the amplifiers’ gains all the way down (counter clockwise),
and make sure the AVR is set for “Direct,” “Stereo,” “Bypass” mode, etc. – i.e.
a straight two-channel signal.

Start the pink noise signal and turn the
AVR’s volume control to the setting you previously determined delivered the
highest clean (undistorted) signal. (See Part 7 if you’re unsure where that is).
Then, increase the amplifier’s gain control until the clipping indicator begins
to blink. Keep increasing the gain until the flickering indicator resolves to
being lit steady. What we accomplish by setting the amplifier’s gain to clipping
with a just-below clipping signal from the pre amp is that both will reach
clipping at the same time in actual use. This is the goal of a successful gain

Repeat the process for all outboard amplifiers in the system.
If you’re also using amplifiers for the rear channels, we can’t give them a
dedicated signal, but you can connect them to the AVR’s main channel outputs for
this gain-setting processes, then move their connections back where they belong
afterward. Center-channel amplifier gain-setting can be accomplished by
switching the AVR to Dolby Pro Logic.

Read more: http://www.hometheatershack.com/forums/home-theater-receivers-processors-amps/35677-gain-structure-home-theater-getting-most-pro-audio-equipment-your-system.html#ixzz2eKSISR22

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