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Overheating amplifier

ashleykr145

New member
Mar 25, 2013
6
0
0
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
 

ashleykr145

New member
Mar 25, 2013
6
0
0
Yeah it sounds fine. I power the amp from the wall socket too (had previous problems on extension cable with other units).
 

TrevC

Well-known member
Jun 12, 2013
301
128
19,070
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".
 

ashleykr145

New member
Mar 25, 2013
6
0
0
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".
Thanks TrevC this is obviously not the news I wanted to hear! Is there anything I can do to alleviate the problem? Or is it the case of saving in the meantime for a new amp and running it as I would?
 

expat_mike

Well-known member
Mar 30, 2013
160
3
18,595
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.
 

BigH

New member
Dec 29, 2012
97
0
0
Is it still under warranty? If it is I would take back to the dealer if he is local. Odd that it only happens on phono, what cartridge have you got?
 

ashleykr145

New member
Mar 25, 2013
6
0
0
BigH said:
Is it still under warranty? If it is I would take back to the dealer if he is local. Odd that it only happens on phono, what cartridge have you got?
Out of warrantee unfortunately. It's an Ortofon silver moving magnet. I might email Roksan none the less explaining my problem.
 

BigH

New member
Dec 29, 2012
97
0
0
ashleykr145 said:
BigH said:
Is it still under warranty? If it is I would take back to the dealer if he is local. Odd that it only happens on phono, what cartridge have you got?
Out of warrantee unfortunately. It's an Ortofon silver moving magnet. I might email Roksan none the less explaining my problem.
Yes best to contact them, maybe they will fix it for free?
 

TrevC

Well-known member
Jun 12, 2013
301
128
19,070
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.
 

expat_mike

Well-known member
Mar 30, 2013
160
3
18,595
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.
 

andyjm

New member
Jul 20, 2012
15
0
0
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.
Perhaps to reword Trevc's comments, the error was assuming that the lower the input voltage, the harder the amplifier had to work for the same output level. The gain stages in an amplifier are generally class A and operate at very low wattages - producing little or no heat no matter the amount of gain required. It is only the output power stages that produce heat, and for the same level output will produce the same amount of heat irrespective of the input level.

The interesting point made above is that it is likely to be the subsonic output of the cartridge causing the amp to overheat. The amp is wasting its time and effort amplifying large low frequency swings that you can't hear. Might be interesting to see if the speaker cones are moving in and out madly at low frequency which would confirm the diagnosis. Just another point in the long laundry list of problems with using vinyl.

The usual fix is to include a subsonic filter in the phono stage - sometimes these are switchable.
 

Al ears

Moderator
andyjm said:
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.
Perhaps to reword Trevc's comments, the error was assuming that the lower the input voltage, the harder the amplifier had to work for the same output level. The gain stages in an amplifier are generally class A and operate at very low wattages - producing little or no heat no matter the amount of gain required. It is only the output power stages that produce heat, and for the same level output will produce the same amount of heat irrespective of the input level.

The interesting point made above is that it is likely to be the subsonic output of the cartridge causing the amp to overheat. The amp is wasting its time and effort amplifying large low frequency swings that you can't hear. Might be interesting to see if the speaker cones are moving in and out madly at low frequency which would confirm the diagnosis. Just another point in the long laundry list of problems with using vinyl.

The usual fix is to include a subsonic filter in the phono stage - sometimes these are switchable.
Which particular Project turntable is being used?
 

Al ears

Moderator
andyjm said:
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.
Perhaps to reword Trevc's comments, the error was assuming that the lower the input voltage, the harder the amplifier had to work for the same output level. The gain stages in an amplifier are generally class A and operate at very low wattages - producing little or no heat no matter the amount of gain required. It is only the output power stages that produce heat, and for the same level output will produce the same amount of heat irrespective of the input level.

The interesting point made above is that it is likely to be the subsonic output of the cartridge causing the amp to overheat. The amp is wasting its time and effort amplifying large low frequency swings that you can't hear. Might be interesting to see if the speaker cones are moving in and out madly at low frequency which would confirm the diagnosis. Just another point in the long laundry list of problems with using vinyl.

The usual fix is to include a subsonic filter in the phono stage - sometimes these are switchable.
Which particular Project turntable is being used? Would suggest borrowing a phono preamp and connecting this and turntable to the Roksans Aux input to see if it does the same thing.
 

ashleykr145

New member
Mar 25, 2013
6
0
0
andyjm said:
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.
Perhaps to reword Trevc's comments, the error was assuming that the lower the input voltage, the harder the amplifier had to work for the same output level. The gain stages in an amplifier are generally class A and operate at very low wattages - producing little or no heat no matter the amount of gain required. It is only the output power stages that produce heat, and for the same level output will produce the same amount of heat irrespective of the input level.

The interesting point made above is that it is likely to be the subsonic output of the cartridge causing the amp to overheat. The amp is wasting its time and effort amplifying large low frequency swings that you can't hear. Might be interesting to see if the speaker cones are moving in and out madly at low frequency which would confirm the diagnosis. Just another point in the long laundry list of problems with using vinyl.

The usual fix is to include a subsonic filter in the phono stage - sometimes these are switchable.
Thanks a test (admittedly a YouTube video) the cones are vibrating at low frequencies (20 Hz) but wouldn't say this was madly, not sure how to test this on the turntable a low bassy song? So potentially a suitable external phono stage could alleviate the problem?
 

strms

New member
Feb 1, 2015
2
0
0
If it is on issue with subsonic frequencies then a 651p is worth a look. I use one for with my 1210 and Ortofon Bronze cart.

https://www.cambridgeaudio.com/products/hifi-and-home-cinema/azur-651p
 

BigH

New member
Dec 29, 2012
97
0
0
strms said:
If it is on issue with subsonic frequencies then a 651p is worth a look. I use one for with my 1210 and Ortofon Bronze cart.

https://www.cambridgeaudio.com/products/hifi-and-home-cinema/azur-651p
Or you buy the CAMBRIDGE AUDIO

AZUR 551P for half that price, believe its the same apart from switch and its for MM only.
 

strms

New member
Feb 1, 2015
2
0
0
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.
 

BigH

New member
Dec 29, 2012
97
0
0
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?
 

MajorFubar

New member
Mar 3, 2010
690
3
0
BigH said:
Seems to be a know issue on Projects: http://www.theapplechap.webspace.virginmedia.com/TheAppleChap/Blog/Entries/2011/5/24_Enhancing_the_sound_from_Pro-ject_turntables_by_removing_rumble.html

Seems Project have fixed the problems are the recent TTs and there maybe a kit available to upgrade existing TTs.
Didn't like to say but the Pro-ject Debut III I bought for my dad about 10 years ago rumbled like hell below about 40Hz. Always figured it was perhaps a one-off fault because no review I've ever read mentions it.
 

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