Onkyo M-504 at 4ohms

Smwilli

Well-Known Member
I've had one of these for quite some time and love it. I know it's rated at 165 per channel at 8ohms. I've always wondered what it's rated at for 4 ohms because there is no mention of a 4ohm rating in the manual. I've searched the internet and there are a lot of people asking the same question as well.

Well, in my searches, I found this picture listing a 4ohm rating (even though it's only for 1 KHZ, it's still something). Is it legit? Just wondering because I'm powering my Boston A400's with the Onkyo and the A400's are 4ohm.
 

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If you can find a service manual there are often more specs in them.

But, personally, I would have no reservation operating the amp at 4 ohms. You have been, right, without incident?

As for power, I'd speculate the 4 ohm wideband power is 30-40% more than the 8 ohm continuous rating.
 
I wouldn't have any hangups about running it on 4 ohms either. Likely got a bit warm for US standards so it's not listed. The amplifier is stout enough to deal with any normal speaker load. Keep it away from the old Kappa 9s or other impedance "evil" amps, but the normal stuff will run just fine.
 
I wasn't too worried about running it at 4 ohms, I was just surprised to find a 4 ohm rating when the owners and service manual has no 4 ohm mention.
 
Interesting. The M-508 SM mentions 4 ohms (what I found in a quick AK docs search). Yeah, different amps but I'd think they'd have some family consistency.
 
I run an M-504 through a pair of Magnapan SMGa speakers which are rated at a nominal 4 ohms. The amp works and sounds great. However, it runs very warm to borderline hot, while doing so. I use (and highly recommend) a cooling fan otherwise, I think the heat might very well impact the life, of this amp.
 
Greetings;

You might think of adding some ohms in sense of making them about 6 ohms instead of 4. The flip would be add ohms to match Euro common speaker ohms like 7.5- 10? then we also share the 16 ohm speaker category on some amps that can run that. Idea is find the 'sweet spot' for area of a room or arena with wattage needed for listening levels. and make sure you have replacement output transistors etc. on hand. :D
 
All the information you need to know about speaker impedance for the amp appears to be printed on the back of your, and most other amps, receivers and AVR's.

It looks like you can run 1 pair of 4 ohm speakers, or 2 pair of 8 ohm speakers. This means the amp is stable driving a 4 ohm nominal impedance. It can dip bellow safely. It does not mean it will put out 2x the power (+3 db's) it should on paper, Very few amps do. More likely an extra db or 2. As a rule of thumb, When driving a 4 ohm speaker I recommend keeping the amp at -3 db's (1/2 power) to insure it Never clips, runs out of current, or over heats when properly vented.
 
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nominal is avg - meaning it can dip below. If you are running this too hot, you can damage the unit. I would not run it with speakers that hit 4 ohm minimum.

There has to be something not right there with his amp. SMGa's, being a very simple load shouldn't be heating it up like that. Almost purely resistive in nature. I ran my 2.5Rs on an h/k 330c for a couple of years and it never got over average warmth.
 
There has to be something not right there with his amp. SMGa's, being a very simple load shouldn't be heating it up like that. Almost purely resistive in nature. I ran my 2.5Rs on an h/k 330c for a couple of years and it never got over average warmth.

I don't believe there's anything wrong with the amp. I can drive 8 ohm speakers (at high volume like I do the SMGa's) all day long and it gets, just warm.

You're comparing two different amps, paired with different speakers, and somehow coming up with "something not right there with his amp" conclusion.

How warm did your M-504 get when you drove a pair of SMGa's?
 
HK's are known for being a little stouter than the avg. amp. Based on the 504 specs, I would NOT use the amp for anything rated for 4 ohms. 465 watts is the input for this amp - 160 WPC is the output for 8 ohms, that means it is really working to drive a 4 ohm load. This amp is NOT a high current design, like the H-K. If you want a high current variant, you need the Integra version of it.

Even though many amps from this era were really well built, they were not designed for hard to drive speakers, plain and simple. Manual is here:

http://www.onkyousa.com/Products/model.php?m=M-504&class=Amplifier

Read the bottom comment here - http://forum.polkaudio.com/discussion/148226/onkyo-m-504-question

Thank you for the information and I couldn't agree more, with your assessment.

My response to the OP was to let him know that it can be done and that I have done it. However, based on the heat output, it appears to be hard on the amp.
 
I think you are correct on that. As for this lineup, they had the M504 integra, the M506 Integra the M508 Integra, and then the M510 GRAND Integra.

I think....

Pretty amp, if not high current. I have mine on some Vandersteen 2c's and that is the best sound I have owned. Others here tell me, and with some experience, that the best is yet to come when I move up to Krell or Threshold. Whoopie!!
 
There was also an M-505 Integra. I have one and it's built like a tank. It's no where near as pretty as the other M series because it doesn't have meters. The power output I believe is about 105 WPC into 8 ohms.
 
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HK's are known for being a little stouter than the avg. amp. Based on the 504 specs, I would NOT use the amp for anything rated for 4 ohms. 465 watts is the input for this amp - 160 WPC is the output for 8 ohms, that means it is really working to drive a 4 ohm load. This amp is NOT a high current design, like the H-K. If you want a high current variant, you need the Integra version of it.

Even though many amps from this era were really well built, they were not designed for hard to drive speakers, plain and simple. Manual is here:

http://www.onkyousa.com/Products/model.php?m=M-504&class=Amplifier

Read the bottom comment here - http://forum.polkaudio.com/discussion/148226/onkyo-m-504-question

An amp usually will double down in power from 8 to 4 ohms, if designed right, not always the case. I have 2 Denon POA-2200 amps, The specs are 200 WPC into 8 ohms, 450 WPC into 4 and 600 WPC into 2 ohm load. You see these amps did not double going from 4 to 2 ohm, so I would be leery about pushing them beyond that. The fact that Onkyo did not do that with the M-504, leads me to believe it really wasn't designed for that.

Doubling down is nothing but a red herring to this whole thing. Fact is, most amps don't double down, nor is it necessary, and many that claim to only do on paper because they sandbag the higher impedance ratings. My Levinson 23 is a perfect example. If you believe it's 200wpc @ 8 ohms like the spec sheet says I have news for ya, it's not. It's more like 290wpc @ 8. The output specs have been massaged to merely give the impression of doubling down. Don't get me wrong, it's a fine amp, but it doesn't really double down despite what the specs say.

As to the 504, the owner's manual clearly states the amp is compatible with 4 ohm speakers. This takes into account impedance swings.
 
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Thank you for the information and I couldn't agree more, with your assessment.

My response to the OP was to let him know that it can be done and that I have done it. However, based on the heat output, it appears to be hard on the amp.


Of course it will work harder at 4 ohm. But, as someone recently mentioned in another thread, that doesn't mean it's working too hard or abnormally hard. Working harder and working too hard should not be construed as the same.
 
I don't believe there's anything wrong with the amp. I can drive 8 ohm speakers (at high volume like I do the SMGa's) all day long and it gets, just warm.

You're comparing two different amps, paired with different speakers, and somehow coming up with "something not right there with his amp" conclusion.

How warm did your M-504 get when you drove a pair of SMGa's?

LOL, I'm comparing a light duty 20 watt solid state amplifier not rated to drive 4 ohms to a 160 watt, much beefier amplifier with far more output devices and cooling surface area, driving amplifiers that have very similar impedance signatures. Not the big divide you are trying to infer. My situation should have been far worse off than yours, not better in any way. My receiver should have been the first to show duress, and it did not in comparison. It would barely get warm, certainly not anything approaching uncomfortable.
 
HK's are known for being a little stouter than the avg. amp. Based on the 504 specs, I would NOT use the amp for anything rated for 4 ohms. 465 watts is the input for this amp - 160 WPC is the output for 8 ohms, that means it is really working to drive a 4 ohm load. This amp is NOT a high current design, like the H-K. If you want a high current variant, you need the Integra version of it.

Even though many amps from this era were really well built, they were not designed for hard to drive speakers, plain and simple. Manual is here:

http://www.onkyousa.com/Products/model.php?m=M-504&class=Amplifier

Read the bottom comment here - http://forum.polkaudio.com/discussion/148226/onkyo-m-504-question

An amp usually will double down in power from 8 to 4 ohms, if designed right, not always the case. I have 2 Denon POA-2200 amps, The specs are 200 WPC into 8 ohms, 450 WPC into 4 and 600 WPC into 2 ohm load. You see these amps did not double going from 4 to 2 ohm, so I would be leery about pushing them beyond that. The fact that Onkyo did not do that with the M-504, leads me to believe it really wasn't designed for that.

They were spec'ed for 4 ohms overseas, but apparently didn't pass in the US due to heat.

It takes a really stiff amp to double down, and in reality, none can due to power supply impedance, so those manufacturers fudge their power ratings down to hit the number they want at the lowest rated impedance. Most can't do this.

The 330c is nowhere near a "stout" amplifier. Later iterations were much stiffer. It's pretty garden variety but sounds really nice.

And we are still left with a load that isn't difficult for any modest amplifier to drive.
 
I think you are correct on that. As for this lineup, they had the M504 integra, the M506 Integra the M508 Integra, and then the M510 GRAND Integra.

I think....

Pretty amp, if not high current. I have mine on some Vandersteen 2c's and that is the best sound I have owned. Others here tell me, and with some experience, that the best is yet to come when I move up to Krell or Threshold. Whoopie!!

The Onkyo website does brag about their ability to drive low impedance loads. it's a fairly decent current amplifier, but not a Krell style "high current."
 
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