Yamaha M-70 Power Amp w/Level Controls - AVS Forum
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post #1 of 11 Old 02-05-2010, 04:27 PM - Thread Starter
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Hey guys, I have a 1980's era Yamaha M-70 200wpc/2ch power amp with level knobs for both L/R channels. I've been trying to find out what the appropriate setting/level should be when used in conjuction w/my AVR's master volume. Should the amp's levels be turned all the way up, necessitating only incremental adjustments on the AVR's volume knob? Or should the amp's levels be turned down, while cranking the AVR's volume higher?

I read somewhere that it's important to "match" the levels between the amp's gain and the AVR's/pre-pro's volume for optimal sound quality/minimal distortion. How do I perform this matching or can someone direct me to the appropriate forum or thread that addresses my question? Thanks.
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post #2 of 11 Old 02-05-2010, 06:53 PM
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Originally Posted by Edwoo View Post

Hey guys, I have a 1980's era Yamaha M-70 200wpc/2ch power amp with level knobs for both L/R channels. I've been trying to find out what the appropriate setting/level should be when used in conjuction w/my AVR's master volume. Should the amp's levels be turned all the way up, necessitating only incremental adjustments on the AVR's volume knob? Or should the amp's levels be turned down, while cranking the AVR's volume higher?

I read somewhere that it's important to "match" the levels between the amp's gain and the AVR's/pre-pro's volume for optimal sound quality/minimal distortion. How do I perform this matching or can someone direct me to the appropriate forum or thread that addresses my question? Thanks.

I will tell you what I know.

A lower gain is good in the sense that it will require more signal from the pre amp, which "may" reduce noise.

Too low of a gain, could result in pre amp clipping. In other words, if you had to turn your AVR way up to get sound from the external amp, or if the L/R channel trims would have to be set high that can be bad too, IMO.

Too high of a gain could make it harder to match with your internal amps. Unlikely, as most AVRs have pre outs on the low side, so the likely situation is that you will need to max the Yamaha amps' gain.

Therefore, starting with max gain seems like a good starting point. Try to balance your system that way, and if your channel trims seem reasonable (close to 0 as opposed to +12 dB or -12 dB) you are good.

If your channel trims are high, that means you don't have a good match. I think in this case, you would lower Yamaha amp's gain (if I am thinking about this right.)

"But this one goes up to 11"
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post #3 of 11 Old 02-05-2010, 06:58 PM
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I have had the M-70's big brother (M-80) for over ten years now and have used it with four different preamps. I keep the level controls all the way up.
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post #4 of 11 Old 02-05-2010, 07:21 PM - Thread Starter
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Thnx, Michael. When you say channel trim, are you referring to the channel level set by/on the AVR? If so, L=-1 & R=+1.
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post #5 of 11 Old 02-05-2010, 07:35 PM
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Quote:
Originally Posted by Edwoo View Post

Thnx, Michael. When you say channel trim, are you referring to the channel level set by/on the AVR? If so, L=-1 & R=+1.

He would be referring to the amp not the AVR.
Most trim levels should be cranked all the way up and let the AVR control volume...unless you have another amp in the setup that is louder - then you'd need to 'trim' that amp.

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post #6 of 11 Old 02-05-2010, 07:54 PM - Thread Starter
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Originally Posted by Knucklehead90 View Post

He would be referring to the amp not the AVR.
Most trim levels should be cranked all the way up and let the AVR control volume...unless you have another amp in the setup that is louder - then you'd need to 'trim' that amp.

I'm only using this single amp in my 2ch set up. So the L&R level/trim (interchangeable terms?) on the amp should be all the way up - just as BMaugans has his M-80 set. That's how I originally had it set, but then just turned them down to a more conservative midway level, because I wasn't really sure if I should be maxing it out, since the master volume is controlled by my AVR/pre anyway.
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post #7 of 11 Old 02-05-2010, 08:00 PM - Thread Starter
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Originally Posted by BMaugans View Post

I have had the M-70's big brother (M-80) for over ten years now and have used it with four different preamps. I keep the level controls all the way up.

This amp really sounds great, BMaugans. I took it from my dad's house 'cause it wasn't being used for the longest time. I was really surprised that after, what, 25 years this rock is still pumpin' some juice. What's your M-80 rated at? 250-300wpc? And what speakers do they power?
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post #8 of 11 Old 02-05-2010, 08:35 PM
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Quote:
Originally Posted by BMaugans View Post

I have had the M-70's big brother (M-80) for over ten years now and have used it with four different preamps. I keep the level controls all the way up.

I have two M-35 2ch/4ch amps: Keep your amp's volume control at MAX (0 dB) unless there is a specific reason to not do so.

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post #9 of 11 Old 02-06-2010, 08:29 AM
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Quote:
Originally Posted by Edwoo View Post

This amp really sounds great, BMaugans. I took it from my dad's house 'cause it wasn't being used for the longest time. I was really surprised that after, what, 25 years this rock is still pumpin' some juice. What's your M-80 rated at? 250-300wpc? And what speakers do they power?

Yeah, it's 250 wpc IIRC. I drive my trusty Meadowlark Kestrels with it.

And I have a correction - it's actually a model M-85.
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post #10 of 11 Old 02-06-2010, 08:49 AM
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I was referring to the AVRs channel trims. If they get set really high, then you risk clipping the signal from the pre amp. There's been discussion of this, and I think some people have tested it.

AVR pre amp levels are often only 1 Volt RMS. Some combinations of tone controls, room correction settings and channel trims can push the output level into clipping near as I can tell.

Unfortunately, your older amp's input sensitivity could be a bit high, like 1.3 Volts. So you may not be able to reach full output before running out of pre amp level. Which is likey why you will be tuning up the amp's level to max because that's the best you can do.

"But this one goes up to 11"
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post #11 of 11 Old 02-06-2010, 01:12 PM
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Edwoo,

I have the same amp as you. I use two sets of front speakers (Klipsch RF-7s). I have the M-70 powering one set, and an Aragon 2002 (2*200) powering the other. I keep the level controls on the M-70 all the way up and do not notice a difference in volume between the two sets of speakers, at any volume level.
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