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Speaker Trim Problem

post #1 of 8
Thread Starter 
Hey guys, so heres my dilema, I have a PITA room that had always read my center channel around 7 db's louder than my fronts, this has been the case through different receivers, amps and speakers. Pretty annoying as I always have to max out trim to -10 to get it close to 75 lbs. However, I know have some older Parasound amps powering my front three speakers. HCA-1200 MK II (Fronts) and HCA-1000 (In bridged mode for Center channel). They have a volume knobs. I have always kept it maxed out. Am I losing anything by using the volume knob on the Amp for the center channel and turning it down and then re-adjusting the the trim in the receiver to compensate? Is this ok??

Thx for the help. System below

Yamaha RX-Z7 Receiver
Parasound HCA-1200 MK II
Parasound HCA-1000
Monitor Audio GS60 Fronts
Monitor Audio GSLCR Center
Paradigm Monitor V.2 Surrounds
PB-13 Ultra
post #2 of 8
You should be just fine using the volume knobs. I actually installed volume knobs on my ultra-sensitive Klipsch speakers just for this reason (out of Audyssey's range to EQ). You'll probably want to re-run YPAO after you make your adjustments.
post #3 of 8
Thread Starter 
Thanks for the reply Alan, am I right in assuming that these volume knobs reduce the gain of the amplifier causing the Pre-amp to work harder to reach the same volume? I see on some newer amps that they have gain switches (29db and 23db). Are these knobs more or less the same thing? Just trying to learn and get proper clarification.
post #4 of 8
Now you're getting too technical for me. redface.gif

Hopefully someone with more education than me can chime in here.
post #5 of 8
Gain control works differently in different amplifiers. Sometimes it actually changes the gain, but other times it is simply an attenuator. Volume controls usually reduce (attenuate) the signal into the amplifier, effectively reducing its gain. As for making the preamp "work harder", most preamps have more than enough output to drive most home amplifiers. More output from the preamp is not going to matter in most situations. If you need to turn down the volume, then the preamp won't be working much harder anyway.

Anytime you change the gain structure of your signal chain you need to re-run whatever room-correction system is in your AVR as it needs to reset all the trim levels. If the trims are in the middle of their range, say within half of the total either side (for example within +/-6 if the range is +/-12) you should be fine. Adjust the volume control/gain of your amp to accomplish that and go listen to music or watch movies.

Running the preamp too low will increase noise; too high will increase distortion. In practice there is a huge range over which you will hear no difference because there is plenty of dynamic range available.

HTH - Don
post #6 of 8
Ideally, you should always set your volume as close to the speakers as possible so your signal level and thus SNR can stay as high as possible for as long as possible. But the difference in your case will be so minor that my advice is, "it doesn't matter as long as you don't drive anything into distortion." There's an argument for doing it your way, too - the digital controls in the receiver are more precise unless you are using a meter to measure the exact effect of the gain knob on the amp.
post #7 of 8
Thread Starter 
Awesome replys guys, the reason I am turning down the volume on the amp is because I am using the test tones on my Auydssey EQ-1 to level match my sub, my problem was that with my receiver at 0 dB (Reference), even with my center channel trim at -10 (maxed out), it was still around 79 dB and without turning down the volume on the amp. I couldn't properly calibrate without moving my reference point from 0 dB.

From your descriptions, it sounds like I won't have that much of an issue either way. So thank you very much for all your replys!
post #8 of 8
You could check Monoprice, Parts Express, or other places and pick up some in-line attenuators to insert in the interconnect cables to your amplifier. That would attenuate the signal so you could successfully calibrate and get the levels matched.
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