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Overheating amplifier

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andyjm

New member
Jul 20, 2012
15
0
0
TrevC said:
BigH said:
strms said:
I don't think that the 551p has a sonic filter as the 651p has a filter 'on/off' switch where the 551p doesn't.
I thought the on/off switch was for power?

Sonic filter for what?
Subsonic filter, sometimes called a rumble filter.
At the risk of being pedantic, while a rumble filter will also work as a subsonic filter, it has a higher cuttoff frequency as it is aimed at audible rumble, not inaudible subsonic noise (the clue is in the name).

For those too young to remember, turntables have a rash of problems all their own, and terminology to match.

Flutter - fast, cyclical change in speed of the platter, resulting in steady notes sounding as if they have a vibrato effect. Due to poor motor speed control, 'cogging' on a direct drive turntable or (in the days of idler wheels) an out of round idler.

Wow - slower, cyclical change in speed of platter, resulting in steady notes sounding as if they have a Hammond organ 'leslie effect' sound or police siren wow-wow-wow sound. Due to poor motor speed control or (for belt drive turntables) the belt running up and down the motor pulley in an unstable manner.

Rumble - grumbling noise, low frequency but still audible. Due to main bearing noise, badly isolated motor feeding vibrations into the platter or a damaged surface of the idler wheel.

Subsonic noise - inaudible, but very damaging. Usually due to warps in the record.

Low frequency noise is particularly problematic as the RIAA equalisation process reduces low frequencies when the disc is cut, requiring a low frequency boost at playback. This has the effect of boosting both the wanted low frequency signal along with any low frequency noise as well.

These days with DC coupled amps (and amp designers who have forgotten about warped records), I have seen warped records produce startling cone excursions with the bass drivers moving wildly in and out. Along with cooking the amp, this doesn't do the speakers a lot of good, particularly if the voice coil moves out of the magnet air-gap at large excursions. Although self limiting, it can cause the voice coils to overheat and fail.
 
K

keeper of the quays

Guest
Lots of suggestions! Mr big h was the most sensible! Get a external phono stage and see what happens! If same problem occurs? Borrow a turntable? Try that through your amp? I can't see it being heatsinks as Roksan been making amps for ever..i believe Methuselah as a young man owned a Roksan amp! I can't believe they would make such fundamental design error...chances are something in inbuilt phono stage is playing up!
 
K

keeper of the quays

Guest
expat_mike said:
TrevC said:
expat_mike said:
My first thought was that you were not using the phono preamp, and were using one of the other inputs. You would then have been trying to amplify a very small input signal, so to get normal volume from the speakers, you would have needed the amp running at maximum power.

However if you are using the phono inputs, then my initial thoughts were wrong.

I am sure that a Roksan owner will soon be able to explain how to sort things out.
Sadly your first thought was nonsense, but never mind.
Yes, but I do say above that my initial thoughts were wrong- it is unfortunate that you consider me an idiot.
Mr Trev considers everyone who doesn't agree with him a idiot! Lol..In olden days the wise masters were treated badly..then they shuffled off this coil of mortalness...And then! Shazzam...they were right after all..those old sages knew their onions...too late for the old wise men? But us left behind? Were left sadder but wiser! Mr Trev is like this..wise but unappreciated! One day..He will be revered as the great one! ;)
 

Al ears

Moderator
keeper of the quays said:
Lots of suggestions! Mr big h was the most sensible! Get a external phono stage and see what happens! If same problem occurs? Borrow a turntable? Try that through your amp? I can't see it being heatsinks as Roksan been making amps for ever..i believe Methuselah as a young man owned a Roksan amp! I can't believe they would make such fundamental design error...chances are something in inbuilt phono stage is playing up!
The phono preamp route was my suggestion I believe. ;-)
 

shadders

Well-known member
Nov 19, 2009
151
87
18,670
TrevC said:
ashleykr145 said:
Hi,

I am looking for some advice regarding my amplifier. It is a Roksan Kandy 2 and seems to be overheating when I run my Pro-jet turntable through it. It cuts out at mid volumes when using this source and is abnormally hot (it doesn't get anywhere near as hot on other sources - PS4 or Aux with iPad/laptop). I run the TT through the inbuilt phono stage but am not sure whether this is potentially causing the overheating? Should I send the amplifier to get serviced or potentially purchase a separate phono stage?

thanks for any help offered

Ashley
It appears to be a design fault. Heatsinks are too small, and there's probably the subsonic energy from vinyl that's causing the problem.

From Stereophile

"Before I test an amplifier, I run it for 60 minutes at one-third its specified power into 8 ohms. Thermally, this worst case for an amplifier with a class-B or -AB output stage taxes its heatsinks' ability to dissipate waste heat. The Kandy K2's top panel got too hot to touch after just 20 minutes; as I could smell hot insulation after 30 minutes, I stopped the preconditioning at that point. The Roksan doesn't have quite enough heatsink area for an amplifier of this power rating".
Hi,

Thread seems to have gotten off track. I assume that your amplifier cuts out once it has heated up, and restores once it has cooled down?

If this happens only on the phono stage input, and at mid way on the volume - from memory, most power is dissipated by the amplifier at approx 1/3 volume levels - then it is possible that the phono stage has a fault. Some faults may require energy to bias the phono stage into a fault condition, which may cause high frequency oscillation (which cannot be heard).

Either way, there seems to be a fault, design, or otherwise, which needs to be examined. You may be able to test yourself if you have an oscilloscope, with the requisite attenuation when connecting to the power output, unless there are preamp outputs.

Regards,

Shadders.
 

BigH

New member
Dec 29, 2012
97
0
0
Well its seems to be a turntable problem, so I would buy the upgrade kit and see if that fixes it. A phono preamp with a rumble filter may fix it but thats a bit more expensive.
 

Al ears

Moderator
BigH said:
Well its seems to be a turntable problem, so I would buy the upgrade kit and see if that fixes it. A phono preamp with a rumble filter may fix it but thats a bit more expensive.
I was only suggesting he try to borrow a phono preamp to prove the fault was in the Roksans inbuilt phono section, not to be an answer to the whole problem.

I remain unconvinced it is a turntable problem.
 

shadders

Well-known member
Nov 19, 2009
151
87
18,670
Hi,

I don't see how the sub sonic rumble of a turntable would be the problem. You could watch the bass driver to see if it's excursion is unnatural compared to normal?

Alternatively if the amplifier has tone controls, reduce the bass accordingly.

Either way, if the amplifier is over heating and cuts out, it is a serious problem, and could cause a catastrophic fire.

I am unaware of the amplifier protection circuit, but the cut out could be due to thermal runaway, and it is the over current sensor that is causing the cut out. It would seem that the amplifier is operating close to the thermal limits and exceeding it regularly. I would expect some form of component degredation due to this.

Regards,

Shadders.
 

TrevC

Well-known member
Jun 12, 2013
305
128
19,070
shadders said:
TrevC said:
ashleykr145 said:
Hi,

I am looking for some advice regarding my amplifier. It is a Roksan Kandy 2 and seems to be overheating when I run my Pro-jet turntable through it. It cuts out at mid volumes when using this source and is abnormally hot (it doesn't get anywhere near as hot on other sources - PS4 or Aux with iPad/laptop). I run the TT through the inbuilt phono stage but am not sure whether this is potentially causing the overheating? Should I send the amplifier to get serviced or potentially purchase a separate phono stage?

thanks for any help offered

Ashley
It appears to be a design fault. Heatsinks are too small, and there's probably the subsonic energy from vinyl that's causing the problem.

From Stereophile

"Before I test an amplifier, I run it for 60 minutes at one-third its specified power into 8 ohms. Thermally, this worst case for an amplifier with a class-B or -AB output stage taxes its heatsinks' ability to dissipate waste heat. The Kandy K2's top panel got too hot to touch after just 20 minutes; as I could smell hot insulation after 30 minutes, I stopped the preconditioning at that point. The Roksan doesn't have quite enough heatsink area for an amplifier of this power rating".
Hi,

Thread seems to have gotten off track. I assume that your amplifier cuts out once it has heated up, and restores once it has cooled down?

If this happens only on the phono stage input, and at mid way on the volume - from memory, most power is dissipated by the amplifier at approx 1/3 volume levels - then it is possible that the phono stage has a fault. Some faults may require energy to bias the phono stage into a fault condition, which may cause high frequency oscillation (which cannot be heard).

Either way, there seems to be a fault, design, or otherwise, which needs to be examined. You may be able to test yourself if you have an oscilloscope, with the requisite attenuation when connecting to the power output, unless there are preamp outputs.

Regards,

Shadders.
If that was the case the amplifier would still overheat with no record playing, so it would be easy to prove without an oscilloscope.
 

TrevC

Well-known member
Jun 12, 2013
305
128
19,070
Al ears said:
BigH said:
Well its seems to be a turntable problem, so I would buy the upgrade kit and see if that fixes it. A phono preamp with a rumble filter may fix it but thats a bit more expensive.
I was only suggesting he try to borrow a phono preamp to prove the fault was in the Roksans inbuilt phono section, not to be an answer to the whole problem.

I remain unconvinced it is a turntable problem.
Correct. It's an amplifier problem. The best advice would be to ditch it and get a decent one.
 

shadders

Well-known member
Nov 19, 2009
151
87
18,670
TrevC said:
shadders said:
TrevC said:
ashleykr145 said:
Hi,

I am looking for some advice regarding my amplifier. It is a Roksan Kandy 2 and seems to be overheating when I run my Pro-jet turntable through it. It cuts out at mid volumes when using this source and is abnormally hot (it doesn't get anywhere near as hot on other sources - PS4 or Aux with iPad/laptop). I run the TT through the inbuilt phono stage but am not sure whether this is potentially causing the overheating? Should I send the amplifier to get serviced or potentially purchase a separate phono stage?

thanks for any help offered

Ashley
It appears to be a design fault. Heatsinks are too small, and there's probably the subsonic energy from vinyl that's causing the problem.

From Stereophile

"Before I test an amplifier, I run it for 60 minutes at one-third its specified power into 8 ohms. Thermally, this worst case for an amplifier with a class-B or -AB output stage taxes its heatsinks' ability to dissipate waste heat. The Kandy K2's top panel got too hot to touch after just 20 minutes; as I could smell hot insulation after 30 minutes, I stopped the preconditioning at that point. The Roksan doesn't have quite enough heatsink area for an amplifier of this power rating".
Hi,

Thread seems to have gotten off track. I assume that your amplifier cuts out once it has heated up, and restores once it has cooled down?

If this happens only on the phono stage input, and at mid way on the volume - from memory, most power is dissipated by the amplifier at approx 1/3 volume levels - then it is possible that the phono stage has a fault. Some faults may require energy to bias the phono stage into a fault condition, which may cause high frequency oscillation (which cannot be heard).

Either way, there seems to be a fault, design, or otherwise, which needs to be examined. You may be able to test yourself if you have an oscilloscope, with the requisite attenuation when connecting to the power output, unless there are preamp outputs.

Regards,

Shadders.
If that was the case the amplifier would still overheat with no record playing, so it would be easy to prove without an oscilloscope.
Hi,

I disagree, some circuits require a specific amount of energy to cause oscillation, which may drive the circuit into the unstable region.

Regards,

Shadders.
 

TrevC

Well-known member
Jun 12, 2013
305
128
19,070
shadders said:
TrevC said:
shadders said:
TrevC said:
ashleykr145 said:
Hi,

I am looking for some advice regarding my amplifier. It is a Roksan Kandy 2 and seems to be overheating when I run my Pro-jet turntable through it. It cuts out at mid volumes when using this source and is abnormally hot (it doesn't get anywhere near as hot on other sources - PS4 or Aux with iPad/laptop). I run the TT through the inbuilt phono stage but am not sure whether this is potentially causing the overheating? Should I send the amplifier to get serviced or potentially purchase a separate phono stage?

thanks for any help offered

Ashley
It appears to be a design fault. Heatsinks are too small, and there's probably the subsonic energy from vinyl that's causing the problem.

From Stereophile

"Before I test an amplifier, I run it for 60 minutes at one-third its specified power into 8 ohms. Thermally, this worst case for an amplifier with a class-B or -AB output stage taxes its heatsinks' ability to dissipate waste heat. The Kandy K2's top panel got too hot to touch after just 20 minutes; as I could smell hot insulation after 30 minutes, I stopped the preconditioning at that point. The Roksan doesn't have quite enough heatsink area for an amplifier of this power rating".
Hi,

Thread seems to have gotten off track. I assume that your amplifier cuts out once it has heated up, and restores once it has cooled down?

If this happens only on the phono stage input, and at mid way on the volume - from memory, most power is dissipated by the amplifier at approx 1/3 volume levels - then it is possible that the phono stage has a fault. Some faults may require energy to bias the phono stage into a fault condition, which may cause high frequency oscillation (which cannot be heard).

Either way, there seems to be a fault, design, or otherwise, which needs to be examined. You may be able to test yourself if you have an oscilloscope, with the requisite attenuation when connecting to the power output, unless there are preamp outputs.

Regards,

Shadders.
If that was the case the amplifier would still overheat with no record playing, so it would be easy to prove without an oscilloscope.
Hi,

I disagree, some circuits require a specific amount of energy to cause oscillation, which may drive the circuit into the unstable region.

Regards,

Shadders.
What circuit are you talking about? The phono preamp? Sounds unlikely to say the least.

I see that this Roksan does have a small heatsink, but it also has a 5 year warranty.
 

Al ears

Moderator
TrevC said:
shadders said:
TrevC said:
shadders said:
TrevC said:
ashleykr145 said:
Hi,

I am looking for some advice regarding my amplifier. It is a Roksan Kandy 2 and seems to be overheating when I run my Pro-jet turntable through it. It cuts out at mid volumes when using this source and is abnormally hot (it doesn't get anywhere near as hot on other sources - PS4 or Aux with iPad/laptop). I run the TT through the inbuilt phono stage but am not sure whether this is potentially causing the overheating? Should I send the amplifier to get serviced or potentially purchase a separate phono stage?

thanks for any help offered

Ashley
It appears to be a design fault. Heatsinks are too small, and there's probably the subsonic energy from vinyl that's causing the problem.

From Stereophile

"Before I test an amplifier, I run it for 60 minutes at one-third its specified power into 8 ohms. Thermally, this worst case for an amplifier with a class-B or -AB output stage taxes its heatsinks' ability to dissipate waste heat. The Kandy K2's top panel got too hot to touch after just 20 minutes; as I could smell hot insulation after 30 minutes, I stopped the preconditioning at that point. The Roksan doesn't have quite enough heatsink area for an amplifier of this power rating".
Hi,

Thread seems to have gotten off track. I assume that your amplifier cuts out once it has heated up, and restores once it has cooled down?

If this happens only on the phono stage input, and at mid way on the volume - from memory, most power is dissipated by the amplifier at approx 1/3 volume levels - then it is possible that the phono stage has a fault. Some faults may require energy to bias the phono stage into a fault condition, which may cause high frequency oscillation (which cannot be heard).

Either way, there seems to be a fault, design, or otherwise, which needs to be examined. You may be able to test yourself if you have an oscilloscope, with the requisite attenuation when connecting to the power output, unless there are preamp outputs.

Regards,

Shadders.
If that was the case the amplifier would still overheat with no record playing, so it would be easy to prove without an oscilloscope.
Hi,

I disagree, some circuits require a specific amount of energy to cause oscillation, which may drive the circuit into the unstable region.

Regards,

Shadders.
What circuit are you talking about? The phono preamp? Sounds unlikely to say the least.

I see that this Roksan does have a small heatsink, but it also has a 5 year warranty.
I'm guessing it is out of warranty.
 

shadders

Well-known member
Nov 19, 2009
151
87
18,670
TrevC said:
shadders said:
TrevC said:
shadders said:
TrevC said:
ashleykr145 said:
Hi,

I am looking for some advice regarding my amplifier. It is a Roksan Kandy 2 and seems to be overheating when I run my Pro-jet turntable through it. It cuts out at mid volumes when using this source and is abnormally hot (it doesn't get anywhere near as hot on other sources - PS4 or Aux with iPad/laptop). I run the TT through the inbuilt phono stage but am not sure whether this is potentially causing the overheating? Should I send the amplifier to get serviced or potentially purchase a separate phono stage?

thanks for any help offered

Ashley
It appears to be a design fault. Heatsinks are too small, and there's probably the subsonic energy from vinyl that's causing the problem.

From Stereophile

"Before I test an amplifier, I run it for 60 minutes at one-third its specified power into 8 ohms. Thermally, this worst case for an amplifier with a class-B or -AB output stage taxes its heatsinks' ability to dissipate waste heat. The Kandy K2's top panel got too hot to touch after just 20 minutes; as I could smell hot insulation after 30 minutes, I stopped the preconditioning at that point. The Roksan doesn't have quite enough heatsink area for an amplifier of this power rating".
Hi,

Thread seems to have gotten off track. I assume that your amplifier cuts out once it has heated up, and restores once it has cooled down?

If this happens only on the phono stage input, and at mid way on the volume - from memory, most power is dissipated by the amplifier at approx 1/3 volume levels - then it is possible that the phono stage has a fault. Some faults may require energy to bias the phono stage into a fault condition, which may cause high frequency oscillation (which cannot be heard).

Either way, there seems to be a fault, design, or otherwise, which needs to be examined. You may be able to test yourself if you have an oscilloscope, with the requisite attenuation when connecting to the power output, unless there are preamp outputs.

Regards,

Shadders.
If that was the case the amplifier would still overheat with no record playing, so it would be easy to prove without an oscilloscope.
Hi,

I disagree, some circuits require a specific amount of energy to cause oscillation, which may drive the circuit into the unstable region.

Regards,

Shadders.
What circuit are you talking about? The phono preamp? Sounds unlikely to say the least.

I see that this Roksan does have a small heatsink, but it also has a 5 year warranty.
Hi,

The original poster states ONLY when using the phono stage input does this occur, and that other inputs are ok. Hence, the logic that it is the phono stage.

Regards,

Shadders.
 

davedotco

New member
Apr 24, 2013
20
0
0
I have noticed in recent times a fair number of vinyl based systems that seem to suffer from subsonic noise, you can't hear it but it is most noticeable on ported speakers as the cone movement is clearly excessive.

So we could have a combination effect occuring here, records themselves are 'noisey' at subsonic frequencies, warp noise and recorded rumble in the first instance. Then the player itself adds more noise, rumble most obviously but unsprung players will often 'sound off' from low frequencies transmitted through the structure of the building.

Few phono stages seem to have much in the way of 'subsonic' or 'rumble' filters so the subsonic signals, further amplified by the RIAA curve are amplified to very high levels. If, as looks likely in this case, the amplifier has insufficient heatsink, then it will run very hot.

You can fix this at virtually every stage, a better lower noise player, a better support, a phono stage with a decent subsonic filter, an amplifier with a controlled bandwidth or more substantial heatsink. All will, in all likelyhood, make an improvement.

Take your pick.
 

shadders

Well-known member
Nov 19, 2009
151
87
18,670
Hi,

Just checked, the K2 has a preamp output, so you could check with an oscilloscope when running the turntable, or capture to a soundcard input (PC), and use Audacity to perform an FFT, to see where the energy resides.

Regards,

Shadders.
 

TrevC

Well-known member
Jun 12, 2013
305
128
19,070
shadders said:
TrevC said:
shadders said:
TrevC said:
shadders said:
TrevC said:
ashleykr145 said:
Hi,

I am looking for some advice regarding my amplifier. It is a Roksan Kandy 2 and seems to be overheating when I run my Pro-jet turntable through it. It cuts out at mid volumes when using this source and is abnormally hot (it doesn't get anywhere near as hot on other sources - PS4 or Aux with iPad/laptop). I run the TT through the inbuilt phono stage but am not sure whether this is potentially causing the overheating? Should I send the amplifier to get serviced or potentially purchase a separate phono stage?

thanks for any help offered

Ashley
It appears to be a design fault. Heatsinks are too small, and there's probably the subsonic energy from vinyl that's causing the problem.

From Stereophile

"Before I test an amplifier, I run it for 60 minutes at one-third its specified power into 8 ohms. Thermally, this worst case for an amplifier with a class-B or -AB output stage taxes its heatsinks' ability to dissipate waste heat. The Kandy K2's top panel got too hot to touch after just 20 minutes; as I could smell hot insulation after 30 minutes, I stopped the preconditioning at that point. The Roksan doesn't have quite enough heatsink area for an amplifier of this power rating".
Hi,

Thread seems to have gotten off track. I assume that your amplifier cuts out once it has heated up, and restores once it has cooled down?

If this happens only on the phono stage input, and at mid way on the volume - from memory, most power is dissipated by the amplifier at approx 1/3 volume levels - then it is possible that the phono stage has a fault. Some faults may require energy to bias the phono stage into a fault condition, which may cause high frequency oscillation (which cannot be heard).

Either way, there seems to be a fault, design, or otherwise, which needs to be examined. You may be able to test yourself if you have an oscilloscope, with the requisite attenuation when connecting to the power output, unless there are preamp outputs.

Regards,

Shadders.
If that was the case the amplifier would still overheat with no record playing, so it would be easy to prove without an oscilloscope.
Hi,

I disagree, some circuits require a specific amount of energy to cause oscillation, which may drive the circuit into the unstable region.

Regards,

Shadders.
What circuit are you talking about? The phono preamp? Sounds unlikely to say the least.

I see that this Roksan does have a small heatsink, but it also has a 5 year warranty.
Hi,

The original poster states ONLY when using the phono stage input does this occur, and that other inputs are ok. Hence, the logic that it is the phono stage.

Regards,

Shadders.
So, to recap, it appears to be a design fault. Heatsinks are too small, and there's probably the subsonic energy from vinyl that's causing the problem.

As I said above.
 

shadders

Well-known member
Nov 19, 2009
151
87
18,670
TrevC said:
shadders said:
TrevC said:
shadders said:
TrevC said:
shadders said:
TrevC said:
ashleykr145 said:
Hi,

I am looking for some advice regarding my amplifier. It is a Roksan Kandy 2 and seems to be overheating when I run my Pro-jet turntable through it. It cuts out at mid volumes when using this source and is abnormally hot (it doesn't get anywhere near as hot on other sources - PS4 or Aux with iPad/laptop). I run the TT through the inbuilt phono stage but am not sure whether this is potentially causing the overheating? Should I send the amplifier to get serviced or potentially purchase a separate phono stage?

thanks for any help offered

Ashley
It appears to be a design fault. Heatsinks are too small, and there's probably the subsonic energy from vinyl that's causing the problem.

From Stereophile

"Before I test an amplifier, I run it for 60 minutes at one-third its specified power into 8 ohms. Thermally, this worst case for an amplifier with a class-B or -AB output stage taxes its heatsinks' ability to dissipate waste heat. The Kandy K2's top panel got too hot to touch after just 20 minutes; as I could smell hot insulation after 30 minutes, I stopped the preconditioning at that point. The Roksan doesn't have quite enough heatsink area for an amplifier of this power rating".
Hi,

Thread seems to have gotten off track. I assume that your amplifier cuts out once it has heated up, and restores once it has cooled down?

If this happens only on the phono stage input, and at mid way on the volume - from memory, most power is dissipated by the amplifier at approx 1/3 volume levels - then it is possible that the phono stage has a fault. Some faults may require energy to bias the phono stage into a fault condition, which may cause high frequency oscillation (which cannot be heard).

Either way, there seems to be a fault, design, or otherwise, which needs to be examined. You may be able to test yourself if you have an oscilloscope, with the requisite attenuation when connecting to the power output, unless there are preamp outputs.

Regards,

Shadders.
If that was the case the amplifier would still overheat with no record playing, so it would be easy to prove without an oscilloscope.
Hi,

I disagree, some circuits require a specific amount of energy to cause oscillation, which may drive the circuit into the unstable region.

Regards,

Shadders.
What circuit are you talking about? The phono preamp? Sounds unlikely to say the least.

I see that this Roksan does have a small heatsink, but it also has a 5 year warranty.
Hi,

The original poster states ONLY when using the phono stage input does this occur, and that other inputs are ok. Hence, the logic that it is the phono stage.

Regards,

Shadders.
So, to recap, it appears to be a design fault. Heatsinks are too small, and there's probably the subsonic energy from vinyl that's causing the problem.

As I said above.
Hi,

No, the energy causing the overheating could be high frequency due to a fault in the phono preamp. Until the original poster conducts tests, we can only guess.

Regards,

Shadders.
 

Al ears

Moderator
shadders said:
TrevC said:
shadders said:
TrevC said:
shadders said:
TrevC said:
shadders said:
TrevC said:
ashleykr145 said:
Hi,

I am looking for some advice regarding my amplifier. It is a Roksan Kandy 2 and seems to be overheating when I run my Pro-jet turntable through it. It cuts out at mid volumes when using this source and is abnormally hot (it doesn't get anywhere near as hot on other sources - PS4 or Aux with iPad/laptop). I run the TT through the inbuilt phono stage but am not sure whether this is potentially causing the overheating? Should I send the amplifier to get serviced or potentially purchase a separate phono stage?

thanks for any help offered

Ashley
It appears to be a design fault. Heatsinks are too small, and there's probably the subsonic energy from vinyl that's causing the problem.

From Stereophile

"Before I test an amplifier, I run it for 60 minutes at one-third its specified power into 8 ohms. Thermally, this worst case for an amplifier with a class-B or -AB output stage taxes its heatsinks' ability to dissipate waste heat. The Kandy K2's top panel got too hot to touch after just 20 minutes; as I could smell hot insulation after 30 minutes, I stopped the preconditioning at that point. The Roksan doesn't have quite enough heatsink area for an amplifier of this power rating".
Hi,

Thread seems to have gotten off track. I assume that your amplifier cuts out once it has heated up, and restores once it has cooled down?

If this happens only on the phono stage input, and at mid way on the volume - from memory, most power is dissipated by the amplifier at approx 1/3 volume levels - then it is possible that the phono stage has a fault. Some faults may require energy to bias the phono stage into a fault condition, which may cause high frequency oscillation (which cannot be heard).

Either way, there seems to be a fault, design, or otherwise, which needs to be examined. You may be able to test yourself if you have an oscilloscope, with the requisite attenuation when connecting to the power output, unless there are preamp outputs.

Regards,

Shadders.
If that was the case the amplifier would still overheat with no record playing, so it would be easy to prove without an oscilloscope.
Hi,

I disagree, some circuits require a specific amount of energy to cause oscillation, which may drive the circuit into the unstable region.

Regards,

Shadders.
What circuit are you talking about? The phono preamp? Sounds unlikely to say the least.

I see that this Roksan does have a small heatsink, but it also has a 5 year warranty.
Hi,

The original poster states ONLY when using the phono stage input does this occur, and that other inputs are ok. Hence, the logic that it is the phono stage.

Regards,

Shadders.
So, to recap, it appears to be a design fault. Heatsinks are too small, and there's probably the subsonic energy from vinyl that's causing the problem.

As I said above.
Hi,

No, the energy causing the overheating could be high frequency due to a fault in the phono preamp. Until the original poster conducts tests, we can only guess.

Regards,

Shadders.
Unfortunately the OP seems to have been scared off. There are still many unanswered questions that could test either / or. A check up of the amp by someone qualified might be a start or dealer if it is still in warranty, which I doubt.
 

TrevC

Well-known member
Jun 12, 2013
305
128
19,070
shadders said:
TrevC said:
shadders said:
TrevC said:
shadders said:
TrevC said:
shadders said:
TrevC said:
ashleykr145 said:
Hi,

I am looking for some advice regarding my amplifier. It is a Roksan Kandy 2 and seems to be overheating when I run my Pro-jet turntable through it. It cuts out at mid volumes when using this source and is abnormally hot (it doesn't get anywhere near as hot on other sources - PS4 or Aux with iPad/laptop). I run the TT through the inbuilt phono stage but am not sure whether this is potentially causing the overheating? Should I send the amplifier to get serviced or potentially purchase a separate phono stage?

thanks for any help offered

Ashley
It appears to be a design fault. Heatsinks are too small, and there's probably the subsonic energy from vinyl that's causing the problem.

From Stereophile

"Before I test an amplifier, I run it for 60 minutes at one-third its specified power into 8 ohms. Thermally, this worst case for an amplifier with a class-B or -AB output stage taxes its heatsinks' ability to dissipate waste heat. The Kandy K2's top panel got too hot to touch after just 20 minutes; as I could smell hot insulation after 30 minutes, I stopped the preconditioning at that point. The Roksan doesn't have quite enough heatsink area for an amplifier of this power rating".
Hi,

Thread seems to have gotten off track. I assume that your amplifier cuts out once it has heated up, and restores once it has cooled down?

If this happens only on the phono stage input, and at mid way on the volume - from memory, most power is dissipated by the amplifier at approx 1/3 volume levels - then it is possible that the phono stage has a fault. Some faults may require energy to bias the phono stage into a fault condition, which may cause high frequency oscillation (which cannot be heard).

Either way, there seems to be a fault, design, or otherwise, which needs to be examined. You may be able to test yourself if you have an oscilloscope, with the requisite attenuation when connecting to the power output, unless there are preamp outputs.

Regards,

Shadders.
If that was the case the amplifier would still overheat with no record playing, so it would be easy to prove without an oscilloscope.
Hi,

I disagree, some circuits require a specific amount of energy to cause oscillation, which may drive the circuit into the unstable region.

Regards,

Shadders.
What circuit are you talking about? The phono preamp? Sounds unlikely to say the least.

I see that this Roksan does have a small heatsink, but it also has a 5 year warranty.
Hi,

The original poster states ONLY when using the phono stage input does this occur, and that other inputs are ok. Hence, the logic that it is the phono stage.

Regards,

Shadders.
So, to recap, it appears to be a design fault. Heatsinks are too small, and there's probably the subsonic energy from vinyl that's causing the problem.

As I said above.
Hi,

No, the energy causing the overheating could be high frequency due to a fault in the phono preamp. Until the original poster conducts tests, we can only guess.

Regards,

Shadders.
Then it will still overheat without the record playing.
 

shadders

Well-known member
Nov 19, 2009
151
87
18,670
TrevC said:
shadders said:
TrevC said:
shadders said:
TrevC said:
shadders said:
TrevC said:
shadders said:
TrevC said:
ashleykr145 said:
Hi,

I am looking for some advice regarding my amplifier. It is a Roksan Kandy 2 and seems to be overheating when I run my Pro-jet turntable through it. It cuts out at mid volumes when using this source and is abnormally hot (it doesn't get anywhere near as hot on other sources - PS4 or Aux with iPad/laptop). I run the TT through the inbuilt phono stage but am not sure whether this is potentially causing the overheating? Should I send the amplifier to get serviced or potentially purchase a separate phono stage?

thanks for any help offered

Ashley
It appears to be a design fault. Heatsinks are too small, and there's probably the subsonic energy from vinyl that's causing the problem.

From Stereophile

"Before I test an amplifier, I run it for 60 minutes at one-third its specified power into 8 ohms. Thermally, this worst case for an amplifier with a class-B or -AB output stage taxes its heatsinks' ability to dissipate waste heat. The Kandy K2's top panel got too hot to touch after just 20 minutes; as I could smell hot insulation after 30 minutes, I stopped the preconditioning at that point. The Roksan doesn't have quite enough heatsink area for an amplifier of this power rating".
Hi,

Thread seems to have gotten off track. I assume that your amplifier cuts out once it has heated up, and restores once it has cooled down?

If this happens only on the phono stage input, and at mid way on the volume - from memory, most power is dissipated by the amplifier at approx 1/3 volume levels - then it is possible that the phono stage has a fault. Some faults may require energy to bias the phono stage into a fault condition, which may cause high frequency oscillation (which cannot be heard).

Either way, there seems to be a fault, design, or otherwise, which needs to be examined. You may be able to test yourself if you have an oscilloscope, with the requisite attenuation when connecting to the power output, unless there are preamp outputs.

Regards,

Shadders.
If that was the case the amplifier would still overheat with no record playing, so it would be easy to prove without an oscilloscope.
Hi,

I disagree, some circuits require a specific amount of energy to cause oscillation, which may drive the circuit into the unstable region.

Regards,

Shadders.
What circuit are you talking about? The phono preamp? Sounds unlikely to say the least.

I see that this Roksan does have a small heatsink, but it also has a 5 year warranty.
Hi,

The original poster states ONLY when using the phono stage input does this occur, and that other inputs are ok. Hence, the logic that it is the phono stage.

Regards,

Shadders.
So, to recap, it appears to be a design fault. Heatsinks are too small, and there's probably the subsonic energy from vinyl that's causing the problem.

As I said above.
Hi,

No, the energy causing the overheating could be high frequency due to a fault in the phono preamp. Until the original poster conducts tests, we can only guess.

Regards,

Shadders.
Then it will still overheat without the record playing.
Hi,

No, not if the fault requires some energy to put the phono stage into oscillation. If the original poster can capture the preamp stage output using a soundcard, then they can use Audacity to analyse the spectrum to see where the energy appears.

Electronics are not either 100% stable, or 100% unstable, there is always some grey area in between where some conditions can cause instability, such as capacitive loads on the amplifier output.

Regards,

Shadders.
 
K

keeper of the quays

Guest
I can send the op my spare phono stage..they can then try it to see? If it makes no difference? Amp is faulty! If it makes a difference then phono stage is faulty! Tape it off..never use it again..life is as simple as you want to make it?
 

TrevC

Well-known member
Jun 12, 2013
305
128
19,070
shadders said:
TrevC said:
shadders said:
TrevC said:
shadders said:
TrevC said:
shadders said:
TrevC said:
shadders said:
TrevC said:
ashleykr145 said:
Hi,

I am looking for some advice regarding my amplifier. It is a Roksan Kandy 2 and seems to be overheating when I run my Pro-jet turntable through it. It cuts out at mid volumes when using this source and is abnormally hot (it doesn't get anywhere near as hot on other sources - PS4 or Aux with iPad/laptop). I run the TT through the inbuilt phono stage but am not sure whether this is potentially causing the overheating? Should I send the amplifier to get serviced or potentially purchase a separate phono stage?

thanks for any help offered

Ashley
It appears to be a design fault. Heatsinks are too small, and there's probably the subsonic energy from vinyl that's causing the problem.

From Stereophile

"Before I test an amplifier, I run it for 60 minutes at one-third its specified power into 8 ohms. Thermally, this worst case for an amplifier with a class-B or -AB output stage taxes its heatsinks' ability to dissipate waste heat. The Kandy K2's top panel got too hot to touch after just 20 minutes; as I could smell hot insulation after 30 minutes, I stopped the preconditioning at that point. The Roksan doesn't have quite enough heatsink area for an amplifier of this power rating".
Hi,

Thread seems to have gotten off track. I assume that your amplifier cuts out once it has heated up, and restores once it has cooled down?

If this happens only on the phono stage input, and at mid way on the volume - from memory, most power is dissipated by the amplifier at approx 1/3 volume levels - then it is possible that the phono stage has a fault. Some faults may require energy to bias the phono stage into a fault condition, which may cause high frequency oscillation (which cannot be heard).

Either way, there seems to be a fault, design, or otherwise, which needs to be examined. You may be able to test yourself if you have an oscilloscope, with the requisite attenuation when connecting to the power output, unless there are preamp outputs.

Regards,

Shadders.
If that was the case the amplifier would still overheat with no record playing, so it would be easy to prove without an oscilloscope.
Hi,

I disagree, some circuits require a specific amount of energy to cause oscillation, which may drive the circuit into the unstable region.

Regards,

Shadders.
What circuit are you talking about? The phono preamp? Sounds unlikely to say the least.

I see that this Roksan does have a small heatsink, but it also has a 5 year warranty.
Hi,

The original poster states ONLY when using the phono stage input does this occur, and that other inputs are ok. Hence, the logic that it is the phono stage.

Regards,

Shadders.
So, to recap, it appears to be a design fault. Heatsinks are too small, and there's probably the subsonic energy from vinyl that's causing the problem.

As I said above.
Hi,

No, the energy causing the overheating could be high frequency due to a fault in the phono preamp. Until the original poster conducts tests, we can only guess.

Regards,

Shadders.
Then it will still overheat without the record playing.
Hi,

No, not if the fault requires some energy to put the phono stage into oscillation. If the original poster can capture the preamp stage output using a soundcard, then they can use Audacity to analyse the spectrum to see where the energy appears.

Electronics are not either 100% stable, or 100% unstable, there is always some grey area in between where some conditions can cause instability, such as capacitive loads on the amplifier output.

Regards,

Shadders.
The energy will appear once the needle hits the record. That won't be oscillation in the preamp, it will be the roar and subsonic noise from the vinyl or turntable. Capacitance can make what unstable?
 

TrevC

Well-known member
Jun 12, 2013
305
128
19,070
keeper of the quays said:
I can send the op my spare phono stage..they can then try it to see? If it makes no difference? Amp is faulty! If it makes a difference then phono stage is faulty! Tape it off..never use it again..life is as simple as you want to make it?
Agreed. Whatever the problem is it's in the amplifier.
 

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