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Old 9th January 2008, 04:59 AM   #1
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Default Got Onkyo M-504 amp out of repair yay! 2 Q's

Hello, I don't know if you guys will remember but I found an Onkyo Integra M-504 dual mobo power amp at goodwill for 20 dollars in like new condition and couldn't get any output. I took it to Innersound in Portland and they desoldered and reflowed the the entire board. That's all it needed, 140 dollars. They then checked every thing else and said all looks mint. It sounds incredible, best amp I have owend.

First question: I don't have a preamp so is it save to plug my ipod into it until I get one?

Question 2: The amp is rated at 165 watts rms at 8 ohms, would someone be able to tell me what it might be rated at 4 ohms. If any additional info is needed let me know because I would really like to know.

Thank you all for any info
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Old 9th January 2008, 11:54 PM   #2
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bump, any help?

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Old 10th January 2008, 08:13 PM   #3
mlloyd1 is offline mlloyd1  United States
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i haven't looked at these amps in quite a while, so don't trust my memory.
often, specs like power into 4ohm loads are included in the users manual.
here is a link to free users manuals if you need it:

as i recall, they are nice amps! $20 is a steal

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Old 11th January 2008, 04:21 AM   #4
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Dan you lucky b......

This was a very famous amp way back (and good looking).

As I recall, the only major problem with this amp is that the max Working Voltage of big power supply caps is almost the same as the rail voltages which have coused several caps to blow up

Many have replaced these to ones with higher WV and higher capacity with good result
Free Schematic and Service Manual downloads, Spare time company (just for fun):
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Old 11th January 2008, 05:28 AM   #5
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mlloyd1, thank you for the link, good info in there.
I love the way this amp looks. I think I read somewhere about the power supply caps being changed often. I may have to look into that.

Thank you both for chiming in.

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Old 28th May 2012, 01:46 PM   #6
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this is kinda of an old thread...does anyone know what the 4 Ohm power of this amp is...
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Old 28th May 2012, 03:02 PM   #7
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If there is no 4ohm spec in the manual, it means this amp is not intended to be used below 8 ohms, and may blow up if tried.
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Old 28th May 2012, 07:19 PM   #8
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strange...says use 4-16 ohm speakers on the back of the amp!
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Old 29th May 2012, 07:40 AM   #9
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Default 4R power rating

You can use most solid state amplifiers down to very low impedances - but not at higher power. (like say, twice the 8R power.)
You are limited by expensive parts like the power transformer, number of output devices and heatsinks, so it was not unusual
to go for just 8R power and sacrifice maximum 4R power at a time when it was not so commonly needed in domestic use.
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Old 5th September 2014, 09:05 PM   #10
mcsue22 is offline mcsue22  United States
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I know this is an old thread, but I think they never published 4ohm specs because they weren't that impressive. Like how most people expect a serious power amp to double down as impedance halves.
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