Amplifier trouble shooting

[GavJ]

Hi, not sure if this is a case of a little knowledge is a dangerous thing or not..... I am interested in learning more about electronics, dabbled a bit years ago, ok with home & auto electrics but Hi Fi... not so good. I have a good multimeter but no oscilloscope if that gives an idea of my level, anyway, the problem.

My system is sounding off... just not having the depth that I remember it having. I was blaming my streamer (Systemline) as it's the recent change. SO I went old school and played some CD's... still no sparkle or ooomph...

Now I am suspecting my amps (2 x Linn LK140's) I noticed  bit of heat from them last night... i don't as a habit feel them for heat so not sure if this is normal for being on for about 5 hrs. Now on a possibly un-related incident, my previous power amp (Belles 150a) broke and took out one of the drivers in my speakers (Castle Knight 5's). I was bi amping with one Linn and the Belles. I then got another LK140 and have been using the two of them.

Now I am suspicious of the power amp again.... could there be something else causing damage to the amps?

Im sitting here waiting for my missus to finish watching some dross on catch up TV in the front room, then I'm going to have a look to see if I can find anything. Now other than putting my meter across each of the amps to see if they measure the same, resistance from ground to each speaker socket, same for phono inputs.... I dont know what else I can do?

Any suggestions?

ps, I'm not intending to do any of these measurements with the amp plugged in....

 

[SergeAuckland]

Hi, not sure if this is a case of a little knowledge is a dangerous thing or not..... I am interested in learning more about electronics, dabbled a bit years ago, ok with home & auto electrics but Hi Fi... not so good. I have a good multimeter but no oscilloscope if that gives an idea of my level, anyway, the problem.

My system is sounding off... just not having the depth that I remember it having. I was blaming my streamer (Systemline) as it's the recent change. SO I went old school and played some CD's... still no sparkle or ooomph...

Now I am suspecting my amps (2 x Linn LK140's) I noticed  bit of heat from them last night... i don't as a habit feel them for heat so not sure if this is normal for being on for about 5 hrs. Now on a possibly un-related incident, my previous power amp (Belles 150a) broke and took out one of the drivers in my speakers (Castle Knight 5's). I was bi amping with one Linn and the Belles. I then got another LK140 and have been using the two of them.

Now I am suspicious of the power amp again.... could there be something else causing damage to the amps?

Im sitting here waiting for my missus to finish watching some dross on catch up TV in the front room, then I'm going to have a look to see if I can find anything. Now other than putting my meter across each of the amps to see if they measure the same, resistance from ground to each speaker socket, same for phono inputs.... I dont know what else I can do?

Any suggestions?

ps, I'm not intending to do any of these measurements with the amp plugged in....

That will do nothing of any use to you in diagnosing what's possibly wrong. The chances of both amps having the same fault is pretty slim, so what I would do first is get rid of the (pointless) bi-amping and go back to one amp, try one amp then the other. Are they the same? If so, then I suggest it's most unlikely to be the power amps. 

So what's left:- Pre-amp or loudspeakers. I would try the CD player straight into one of the power amps using a simple volume control wired to a couple of cables to make the connection. That would eliminate the pre-amp, so that leaves the loudspeakers. Again, the chances of both loudspeakers going faulty in the same way is slim, but it might be an idea if you can to try another pair of 'speakers. I see you're in Glasgow, there should be other 'wammers around that might let you try your pre-amp and amps in their system to identify where the problems lie.

S.

 

[GavJ]

Thanks for response Serge...

Managed to get into the room ... at last

Played a couple of tracks, system sounds ok again? Was definitely sounding off last night....

Both my power amps were sitting together, so I seperated them to see if I could tell any difference in temperature. I then ran a test & burn CD, this showed that somehow I have my left & right mixed up!!!

Imaging tests went well, the low frequency test went Low (very low) and the high went very high.... and both power amps heated up a bit, not hot just warm but both the same.

Interesting statement about Bi Amping Serge? When I had only one amp I noticed a marked difference, hence the reason I sought out another LK140, which returned the previous perceived? quality? I wonder how much is in the mind.....

If I can I will leave the system playing today while I'm out and see if it degrades again...

 

[SergeAuckland]

Thanks for response Serge...

Managed to get into the room ... at last

Played a couple of tracks, system sounds ok again? Was definitely sounding off last night....

Both my power amps were sitting together, so I seperated them to see if I could tell any difference in temperature. I then ran a test & burn CD, this showed that somehow I have my left & right mixed up!!!

Imaging tests went well, the low frequency test went Low (very low) and the high went very high.... and both power amps heated up a bit, not hot just warm but both the same.

Interesting statement about Bi Amping Serge? When I had only one amp I noticed a marked difference, hence the reason I sought out another LK140, which returned the previous perceived? quality? I wonder how much is in the mind.....

If I can I will leave the system playing today while I'm out and see if it degrades again...

Indeed! 

S

 

[hifinutt]

you could also contact tony at coherent audio , he works with dave who makes belles on the design

http://www.coherent-systems.co.uk/

 

[GavJ]

Thanks HIfinutt, I sold the Belles as a "spares or repair" a few months ago....... I could have sent the Belles to London for repair but decided just to move on....