Amp overheating
Discussion
I have a Denon AV amp running a pair of Cambridge SX30 speakers and sub. Nothing remarkable about the setup, 2 x 100W capable shelf mounts and an active sub. The amp is rated at;
Power Output (6 ohm, 1 kHz, 0.7% 2ch Drive)
90 W
Power Output (6 ohm, 1 kHz, 1% 1ch Drive)
130 W
Power Output (8 ohm, 20 Hz - 20 kHz, 0.08% 2ch Drive)
70 W
However.... when cranking the volume up the amp is getting hot and cutting out. There is no active cooling (fan) instead the amp just has a heatsink to dissapate the heat. Am I just pushing the amp too hard, or is there some mismatch between speakers and amp?
At this rate may need to invest in something able to work harder, for longer.
Power Output (6 ohm, 1 kHz, 0.7% 2ch Drive)
90 W
Power Output (6 ohm, 1 kHz, 1% 1ch Drive)
130 W
Power Output (8 ohm, 20 Hz - 20 kHz, 0.08% 2ch Drive)
70 W
However.... when cranking the volume up the amp is getting hot and cutting out. There is no active cooling (fan) instead the amp just has a heatsink to dissapate the heat. Am I just pushing the amp too hard, or is there some mismatch between speakers and amp?
At this rate may need to invest in something able to work harder, for longer.
Condi said:
I have a Denon AV amp running a pair of Cambridge SX30 speakers and sub. Nothing remarkable about the setup, 2 x 100W capable shelf mounts and an active sub. The amp is rated at;
Power Output (6 ohm, 1 kHz, 0.7% 2ch Drive)
90 W
Power Output (6 ohm, 1 kHz, 1% 1ch Drive)
130 W
Power Output (8 ohm, 20 Hz - 20 kHz, 0.08% 2ch Drive)
70 W
However.... when cranking the volume up the amp is getting hot and cutting out. There is no active cooling (fan) instead the amp just has a heatsink to dissapate the heat. Am I just pushing the amp too hard, or is there some mismatch between speakers and amp?
At this rate may need to invest in something able to work harder, for longer.
What amp do you have? Does it all have all features you need for now and the future (to a degree - it is changing all the time of course). Power Output (6 ohm, 1 kHz, 0.7% 2ch Drive)
90 W
Power Output (6 ohm, 1 kHz, 1% 1ch Drive)
130 W
Power Output (8 ohm, 20 Hz - 20 kHz, 0.08% 2ch Drive)
70 W
However.... when cranking the volume up the amp is getting hot and cutting out. There is no active cooling (fan) instead the amp just has a heatsink to dissapate the heat. Am I just pushing the amp too hard, or is there some mismatch between speakers and amp?
At this rate may need to invest in something able to work harder, for longer.
If it has pre-outs, it might be worth investing in a good quality power amp. Likely to be an improvement in sound quality and power.
Thanks for the reply's, I'm not really very good with what ohms mean so maybe some learning to do there.
The speakers are 4 ohm, does this increase the power required to drive them? They were admittedly a cheaper set of speakers, although as a student money was somewhat tight years ago. Good set of specs in the link below.
https://www.cnet.com/products/cambridge-audio-s30-...
The amp is not racked, but is in a TV stand. Air can flow round and into the unit, but admittedly this could be a lot better, as there are only a few cm gap above the amp.
The speakers are 4 ohm, does this increase the power required to drive them? They were admittedly a cheaper set of speakers, although as a student money was somewhat tight years ago. Good set of specs in the link below.
https://www.cnet.com/products/cambridge-audio-s30-...
The amp is not racked, but is in a TV stand. Air can flow round and into the unit, but admittedly this could be a lot better, as there are only a few cm gap above the amp.
Condi said:
The speakers are 4 ohm
That was my guess and was already mentioned by 1962 above. Put bluntly, if you want to listen loud you need a new system, or at least a receiver (or amp) that can deliver more grunt. 8 ohm speakers would give your existing amp an easier time but you can achieve that anyway simply by turning down the volume - which isn't what you want.
Sticking a fan in or near the amp to cool it would obviously help with the cutting-out but still leaves you with an amp that's permanently trying to run full throttle so may just burn-out anyway. i.e. Cooling may suppress the symptoms but doesn't address the cause.
heisthegaffer said:
As Mentioned you could get a power amp even just for the fronts. Was looking at a forum that said a good quality PA amp could be a very cost effective solution in terms of £/watts.
This is what I did - check if your AV amp has a pre-out connectors and if it does, go on eBay and get yourself a nice power amp. Dead simple to set up and very effective.Condi said:
The speakers are 4 ohm, does this increase the power required to drive them? They were admittedly a cheaper set of speakers, although as a student money was somewhat tight years ago. Good set of specs in the link below.
4 ohm speakers draw more current, and that’s the killer for your amp. Also, 4 ohm speakers tend to be less sensitive than 6 and 8 ohm speakers. This is measured in dB at 1 metre away for one Watt input. Yours might be 96dB, whereas another speaker might be 91dB. An increase of 3 dB is perceived by us as twice as loud. So, your speakers are giving your amp no chance at all. At least the thermal cut out works!If you like the speakers, keep them and upgrade the amplification. If you’re even thinking a little about changing them, start investigating.
Tony1963 said:
Condi said:
The speakers are 4 ohm, does this increase the power required to drive them? They were admittedly a cheaper set of speakers, although as a student money was somewhat tight years ago. Good set of specs in the link below.
4 ohm speakers draw more current, and that’s the killer for your amp. Also, 4 ohm speakers tend to be less sensitive than 6 and 8 ohm speakers. This is measured in dB at 1 metre away for one Watt input. Yours might be 96dB, whereas another speaker might be 91dB. An increase of 3 dB is perceived by us as twice as loud. So, your speakers are giving your amp no chance at all. At least the thermal cut out works!If you like the speakers, keep them and upgrade the amplification. If you’re even thinking a little about changing them, start investigating.
Agreed, that the 4 ohm Cambridge speakers are almost certain to be the issue; the output stages home cinema amps are not often designed for 4 ohms loads. 8-16 Ohms is typical.
Just to clarify things regarding a point you made, a 4 Ohm impedance speaker will have the same sensitivity as an 8 Ohm unit when fed with 1 watt of power. All other things being equal.
The lower impedance load draws more current for a given amplifier output voltage, consequently a 4 ohm speaker 'demands' twice the number of watts from that amp's power supply relative to an 8 ohm speaker.
Many driver suppliers make the same units available in both 4 ohm and 8 ohm configurations........the 4 ohm unit's sensitivity is invariably shown to be 3db higher than the 8 ohm equivalent. That is because most suppliers measure at 2.83v at 1m; in the case below the 4 ohm driver 'appears' to be more sensitive because it is being fed two watts.
4 ohm version 90.5dB https://www.falconacoustics.co.uk/downloads/SBA/6i...
8 ohm version 87.5dB https://www.falconacoustics.co.uk/downloads/SBA/6i...
Edited by Crackie on Sunday 4th April 10:51
As a quick fix you could add some small fans to the vents, so it is not just passively cooled.
https://www.ebay.co.uk/itm/2pcs-Portable-Mini-Cool...
https://www.ebay.co.uk/itm/2pcs-Portable-Mini-Cool...
I'm not a great electronics guru but Resistance shouldn't be compared directly with Impedance.
Resistance is a DC measure and essentially simple to understand.
But a loudspeaker is an AC device - the speaker cone is both pushed out and pulled back. If you connect a battery to a speaker you'll see the cone jumps forwards (or backwards) and just stays there. You'll get one "pop" and then silence, which isn't very handy for music.
Impedance is sort of an AC equivalent of resistance but it's not the same. Halving the impedance won't necessarily double the current although current is likely to increase significantly. Impedance varies with frequency (i.e. music) so is really a curve, not a fixed value.
Due to the vagaries of Impedance and of loudspeaker design some speakers are simply "easier" or "harder" for an amplifier to drive than others. The nominal Impedance figure doesn't answer this question on its own.
Whatever speaker is attached to it the amplifier can never deliver more voltage to the speaker than the voltage at which the output transistors are running. However, current will try to rise to whatever the speakers want to draw and this is what roasts amplifiers. In very broad terms the more current you want an amplifier to deliver the more expensive it will be to build.
At the end of the day if you want more volume your choices are,
(1) Try listening to your existing speakers driven by a better amplifier. If they sound better, change your amplifier. If they sound the same, change your speakers.
(2) Try listening to your amplifier playing through some really good speakers. If it sounds better, change your speakers. If it sounds the same, change your amplifier.
Run both of these comparisons and you should find out where you are.
Do all speakers sound the same? No
Do all GOOD speakers sound the same? No. Like musical instruments they have an individual tone/timbre/response.
Do all amplifiers sound the same? No
Do all GOOD amplifiers sound the same? In very broad terms I'd suggest the answer is yes.
Your loudspeaker is a motor (coil) doing work - moving the cone backwards and forwards. The lower the frequency the further the cone must be moved to deliver a given sound level. The further you want the cone to move the more work the motor (coil) must do. The more work the motor (coil) is asked to do the more current it must draw at any given voltage. So if you want decent bass you need an amplifier that can deliver a reasonably hefty amount of current without melting itself (or triggering its safety cut-out).
Resistance is a DC measure and essentially simple to understand.
But a loudspeaker is an AC device - the speaker cone is both pushed out and pulled back. If you connect a battery to a speaker you'll see the cone jumps forwards (or backwards) and just stays there. You'll get one "pop" and then silence, which isn't very handy for music.
Impedance is sort of an AC equivalent of resistance but it's not the same. Halving the impedance won't necessarily double the current although current is likely to increase significantly. Impedance varies with frequency (i.e. music) so is really a curve, not a fixed value.
Due to the vagaries of Impedance and of loudspeaker design some speakers are simply "easier" or "harder" for an amplifier to drive than others. The nominal Impedance figure doesn't answer this question on its own.
Whatever speaker is attached to it the amplifier can never deliver more voltage to the speaker than the voltage at which the output transistors are running. However, current will try to rise to whatever the speakers want to draw and this is what roasts amplifiers. In very broad terms the more current you want an amplifier to deliver the more expensive it will be to build.
At the end of the day if you want more volume your choices are,
- Speakers that are easier to drive (i.e. don't give the amplifier such a hard time.)
- Speakers that are more sensitive (i.e. the motor/coil can move the cone further for a given signal.)
- An amplifier with more grunt - principally in the form of ability to deliver more current.
(1) Try listening to your existing speakers driven by a better amplifier. If they sound better, change your amplifier. If they sound the same, change your speakers.
(2) Try listening to your amplifier playing through some really good speakers. If it sounds better, change your speakers. If it sounds the same, change your amplifier.
Run both of these comparisons and you should find out where you are.
Do all speakers sound the same? No
Do all GOOD speakers sound the same? No. Like musical instruments they have an individual tone/timbre/response.
Do all amplifiers sound the same? No
Do all GOOD amplifiers sound the same? In very broad terms I'd suggest the answer is yes.
Your loudspeaker is a motor (coil) doing work - moving the cone backwards and forwards. The lower the frequency the further the cone must be moved to deliver a given sound level. The further you want the cone to move the more work the motor (coil) must do. The more work the motor (coil) is asked to do the more current it must draw at any given voltage. So if you want decent bass you need an amplifier that can deliver a reasonably hefty amount of current without melting itself (or triggering its safety cut-out).
rockin said:
I'm not a great electronics guru but Resistance shouldn't be compared directly with Impedance.
Resistance is a DC measure and essentially simple to understand.
But a loudspeaker is an AC device - the speaker cone is both pushed out and pulled back. If you connect a battery to a speaker you'll see the cone jumps forwards (or backwards) and just stays there. You'll get one "pop" and then silence, which isn't very handy for music.
Impedance is sort of an AC equivalent of resistance but it's not the same. Halving the impedance won't necessarily double the current although current is likely to increase significantly. Impedance varies with frequency (i.e. music) so is really a curve, not a fixed value.
Due to the vagaries of Impedance and of loudspeaker design some speakers are simply "easier" or "harder" for an amplifier to drive than others. The nominal Impedance figure doesn't answer this question on its own.
Whatever speaker is attached to it the amplifier can never deliver more voltage to the speaker than the voltage at which the output transistors are running. However, current will try to rise to whatever the speakers want to draw and this is what roasts amplifiers. In very broad terms the more current you want an amplifier to deliver the more expensive it will be to build.
At the end of the day if you want more volume your choices are,
(1) Try listening to your existing speakers driven by a better amplifier. If they sound better, change your amplifier. If they sound the same, change your speakers.
(2) Try listening to your amplifier playing through some really good speakers. If it sounds better, change your speakers. If it sounds the same, change your amplifier.
Run both of these comparisons and you should find out where you are.
Do all speakers sound the same? No
Do all GOOD speakers sound the same? No. Like musical instruments they have an individual tone/timbre/response.
Do all amplifiers sound the same? No
Do all GOOD amplifiers sound the same? In very broad terms I'd suggest the answer is yes.
Your loudspeaker is a motor (coil) doing work - moving the cone backwards and forwards. The lower the frequency the further the cone must be moved to deliver a given sound level. The further you want the cone to move the more work the motor (coil) must do. The more work the motor (coil) is asked to do the more current it must draw at any given voltage. So if you want decent bass you need an amplifier that can deliver a reasonably hefty amount of current without melting itself (or triggering its safety cut-out).
Good summary.Resistance is a DC measure and essentially simple to understand.
But a loudspeaker is an AC device - the speaker cone is both pushed out and pulled back. If you connect a battery to a speaker you'll see the cone jumps forwards (or backwards) and just stays there. You'll get one "pop" and then silence, which isn't very handy for music.
Impedance is sort of an AC equivalent of resistance but it's not the same. Halving the impedance won't necessarily double the current although current is likely to increase significantly. Impedance varies with frequency (i.e. music) so is really a curve, not a fixed value.
Due to the vagaries of Impedance and of loudspeaker design some speakers are simply "easier" or "harder" for an amplifier to drive than others. The nominal Impedance figure doesn't answer this question on its own.
Whatever speaker is attached to it the amplifier can never deliver more voltage to the speaker than the voltage at which the output transistors are running. However, current will try to rise to whatever the speakers want to draw and this is what roasts amplifiers. In very broad terms the more current you want an amplifier to deliver the more expensive it will be to build.
At the end of the day if you want more volume your choices are,
- Speakers that are easier to drive (i.e. don't give the amplifier such a hard time.)
- Speakers that are more sensitive (i.e. the motor/coil can move the cone further for a given signal.)
- An amplifier with more grunt - principally in the form of ability to deliver more current.
(1) Try listening to your existing speakers driven by a better amplifier. If they sound better, change your amplifier. If they sound the same, change your speakers.
(2) Try listening to your amplifier playing through some really good speakers. If it sounds better, change your speakers. If it sounds the same, change your amplifier.
Run both of these comparisons and you should find out where you are.
Do all speakers sound the same? No
Do all GOOD speakers sound the same? No. Like musical instruments they have an individual tone/timbre/response.
Do all amplifiers sound the same? No
Do all GOOD amplifiers sound the same? In very broad terms I'd suggest the answer is yes.
Your loudspeaker is a motor (coil) doing work - moving the cone backwards and forwards. The lower the frequency the further the cone must be moved to deliver a given sound level. The further you want the cone to move the more work the motor (coil) must do. The more work the motor (coil) is asked to do the more current it must draw at any given voltage. So if you want decent bass you need an amplifier that can deliver a reasonably hefty amount of current without melting itself (or triggering its safety cut-out).
As you say, speakers are not pure resistances they are frequency dependent devices. Their 'load' is determined by many factors including the drivers used, the bass loading method, the crossover topology etc etc.
Most surround amps' output stages and low impedances don't get on. The ones that can cope with low and/or reactive loads are usually the higher end flagship products. Speaker impedances have a reactive component i.e the voltage and current are not in phase with each other. Speakers with low impedances and large phase angles, particularly in the bass region will upset most surround amps ( when they are asked to play at higher volume levels ). To paraphrase. Surround amps are fine with higher 8 ohm type loads, even the reactive ones but they often struggle if presented with a 4 Ohm load, particularly if there is a reactive element to the lower impedance loads. Condi's Denon amp spec doesn't even quote an output power into 4 Ohm loads.
Here is the impedance curve of a pair of Duntech Marquis speakers; they are a very big 4 Ohm design and deliver 92db for 1w at 1m..They have 5 drivers The load is pretty easy though, despite being 4 Ohm designs there are no nasty phase angles i.e they are not particularly reactive and my relatively entry level Yamaha surround amp can cope with them just fine ( at any volume level )
The grey curve at the top of the graph is the phase angle, scale on the right.
Here is the impedance measurement of a small B&W WP1 speaker. It is a more difficult speaker to drive, from the amplifier's perspective. It is also a nominally 4 Ohm device but the phase angles are higher particularly in the upper bass region.
Keith Howard has done some excellent research regarding the dynamic nature of speaker loads and why some speakers are real amp killers. https://www.stereophile.com/reference/707heavy/ind...
Condi said:
Thank you for all the responses. I will have a browse on Richer Sounds and see what they have which is either higher Ohm, or maybe look at a PA.
And then maybe try to understand the nice and detailed response above, thanks you.
Good post from Rockin above And then maybe try to understand the nice and detailed response above, thanks you.
These might fit the bill........... they are a 6Ohm load, which your Denon's spec suggests it is OK with and they claim 92dB for 1w. https://www.richersounds.com/hi-fi/floorstanding-s...
The Denon spec says it can put out 90W into a 6Ohm load when driving 2 channels. This, in conjunction with the 92dB rating of the Q3050 should give a max output of
111dB from a single speaker measured 1m away
114dB from a pair measured 1m away.
108dB from a pair measure 2m away.
102dB from a pair measure 4m away.
paralla said:
I don’t think it is. He said there is 2cm above the amp and it’s inside a cabinet. That’s not enough.
Relocating the amp is an easy fix that doesn’t require spending anything at all.
It might not be an easy fix, and it’ll probably still overheat because too much is being asked of it. If I drive my matched amp and speakers hard for hours on end, the amp case is only just warm. Even in a cabinet it wouldn’t be much warmer. Relocating the amp is an easy fix that doesn’t require spending anything at all.
"Why is your Denon amp overheating despite the spec"
The spec only tells part of the story.
The spec you have suggests your Denon is along the same lines as the AVRX550. It might not be that exact model, but it's similar to this £300 rrp receiver. Denon has been on a bit of a charge to grab market share over the last few years. It is aping what Onkyo started to do almost 15 years ago; it tries to offer the best-in-class paper specification to outgun the competition. That sounds like a good idea in theory, but it didn't work out so well for Onkyo, and I fear that Denon is heading for the same kind of fall.
Onkyo's reputation was torn to shreds when its hot-running receivers started to cook their HDMI and digital audio processing chips. They cut too many corners and pushed the designs harder than they should have. The brand used to be the darling of the trade, but look now. It's a very different story.
There's a lot of smoke an mirrors when it comes to amplifier power ratings. It doesn't help when manufacturers weasel about by not giving full specs. For example, is the 70W/ch figure based on continuous power or instantaneous? It's an important question. It's like the sprinter versus the supercar race. How the information is presented changes the perspective. The sprinter gets of the line quicker, so they won, right?
There's also the stuff that isn't discussed such as the maximum power rating of the output transistors, and whether they're dedicated per channel or shared. It stands to reason that if an output transistor is doing double-duty then it's going to get hotter faster. This is why all those all-in-one DVD/Blu-ray-player-based home cinema kits have fans. Look at decent stereo amps - Denon included - do they have fans?
There's a whole subset of tweakers discussing which are the best USB-powered fans to use to help run the lower to mid-range AVRX series Denon receivers. That should start ringing alarm bells. It does for me.
There's only limited options too to reduce the speaker load on the amp. To get pre-outs in order to run an external power amp means stepping up to the £1000+ AVR-X3700, by which time of course the amp doesn't have as much of an issue with difficult loads. The remining options then are either using the bass management to filter away more mid-bass for the sub to handle, which means avoiding Pure Stereo mode from that point on unless it's at more subdued levels, or changing the speakers for something more benign as a load. That may not be so practical though if the front stereo pair are part of a matched 5.1 system.
Someone mentioned speaker sensitivities. I think that's an important factor when it comes to the power demands made on amps. A difference of 3dB can double or halve the sound pressure level generated by a speaker. That feeds directly ion to the power requirement. Take 1W in to a speaker at 92dB/W/m, and you'll get a measurement of as near as damn it 92dB at 1m from the speaker in an anechoic chamber. Swap the speaker for one rated at 89dB, and all other things being equal, the amp will end up supplying 2 Watts instead of 1 to generate the same 92dB.
What's not true though is that we perceive a difference of a doubling of loudness when the speaker sensitivity increase by 3dB. We don't. 3dB registers with us as marginally louder, but not noticeably so. In order to make a perceived doubling of the loudness it requires 10x the power increase; so 1W to 10W - twice as loud. 10W to 100W - twice as loud again, but only 4 times louder than 1W.
The spec only tells part of the story.
The spec you have suggests your Denon is along the same lines as the AVRX550. It might not be that exact model, but it's similar to this £300 rrp receiver. Denon has been on a bit of a charge to grab market share over the last few years. It is aping what Onkyo started to do almost 15 years ago; it tries to offer the best-in-class paper specification to outgun the competition. That sounds like a good idea in theory, but it didn't work out so well for Onkyo, and I fear that Denon is heading for the same kind of fall.
Onkyo's reputation was torn to shreds when its hot-running receivers started to cook their HDMI and digital audio processing chips. They cut too many corners and pushed the designs harder than they should have. The brand used to be the darling of the trade, but look now. It's a very different story.
There's a lot of smoke an mirrors when it comes to amplifier power ratings. It doesn't help when manufacturers weasel about by not giving full specs. For example, is the 70W/ch figure based on continuous power or instantaneous? It's an important question. It's like the sprinter versus the supercar race. How the information is presented changes the perspective. The sprinter gets of the line quicker, so they won, right?
There's also the stuff that isn't discussed such as the maximum power rating of the output transistors, and whether they're dedicated per channel or shared. It stands to reason that if an output transistor is doing double-duty then it's going to get hotter faster. This is why all those all-in-one DVD/Blu-ray-player-based home cinema kits have fans. Look at decent stereo amps - Denon included - do they have fans?
There's a whole subset of tweakers discussing which are the best USB-powered fans to use to help run the lower to mid-range AVRX series Denon receivers. That should start ringing alarm bells. It does for me.
There's only limited options too to reduce the speaker load on the amp. To get pre-outs in order to run an external power amp means stepping up to the £1000+ AVR-X3700, by which time of course the amp doesn't have as much of an issue with difficult loads. The remining options then are either using the bass management to filter away more mid-bass for the sub to handle, which means avoiding Pure Stereo mode from that point on unless it's at more subdued levels, or changing the speakers for something more benign as a load. That may not be so practical though if the front stereo pair are part of a matched 5.1 system.
Someone mentioned speaker sensitivities. I think that's an important factor when it comes to the power demands made on amps. A difference of 3dB can double or halve the sound pressure level generated by a speaker. That feeds directly ion to the power requirement. Take 1W in to a speaker at 92dB/W/m, and you'll get a measurement of as near as damn it 92dB at 1m from the speaker in an anechoic chamber. Swap the speaker for one rated at 89dB, and all other things being equal, the amp will end up supplying 2 Watts instead of 1 to generate the same 92dB.
What's not true though is that we perceive a difference of a doubling of loudness when the speaker sensitivity increase by 3dB. We don't. 3dB registers with us as marginally louder, but not noticeably so. In order to make a perceived doubling of the loudness it requires 10x the power increase; so 1W to 10W - twice as loud. 10W to 100W - twice as loud again, but only 4 times louder than 1W.
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