[Katonoma]

Hi James,

I 've just noticed my 2 * 28B's are really(I mean really!) hot, the left one much more than the right one, you can't leave your hands on.

This is a bit disturbing since I hadn't experienced this before, I just changed full set of interconnect and speakers cables ;  the amps were MUCH cooler with the previous setup.

Could possibly this have some influence? Do you have any idea where this is coming from?

Christian

[dirk]

Go back to the original cables and change step by step.

[James Tanner]

Hi James,

I 've just noticed my 2 * 28B's are really(I mean really!) hot, the left one much more than the right one, you can't leave your hands on.

This is a bit disturbing since I hadn't experienced this before, I just changed full set of interconnect and speakers cables ;  the amps were MUCH cooler with the previous setup.

Could possibly this have some influence? Do you have any idea where this is coming from?

Christian

Hi Christian,

It sounds like the amps protection circuits or the bias is being affected by the cables.
Please remove them and see if the amps behave normally.  The problem with some of these 'exotic' cables is they do have wierd electrical characteristics sometimes.

What cables are they?

james

[Katonoma]

Wow that was quick response

I have now TARALABS REf GENERATION 2+ Speaker and Interconnect.
I had Kimber Select KS1130 & KS3038 all silver before.

The speaker cables are half shorter (4 feet and now 8 feet).

The problem is that I left my Kimber cables at my local store and won't be able to switch today.

I am in the procees of changing my cable setup , the TARA LABS were just a try.

[James Tanner]

Wow that was quick response

I have now TARALABS REf GENERATION 2+ Speaker and Interconnect.
I had Kimber Select KS1130 & KS3038 all silver before.

The speaker cables are half shorter (4 feet and now 8 feet).

The problem is that I left my Kimber cables at my local store and won't be able to switch today.

I am in the procees of changing my cable setup , the TARA LABS were just a try.

Christian

What happens if you just turn the amps on with NO cables attached?

james

[Katonoma]

OK, I give it a try and get back to you in a couple of hours so that temp adjusts.

Thanks James

[drummermitchell]

Just a thought,besides recabling,did you put the 28s in a different location, how much clearance do the 28s have on top.

[Katonoma]

OK, I give it a try and get back to you in a couple of hours so that temp adjusts.

Thanks James

James,

I did a few Infrared Camera shots of both amps running now for a couple hours speaker cables disconnected.

The temperature displayed is the one at the central point of the picture. Because of the measurement tehnology, it's not a precise value and can be different from the real by 2 or 3 degrees.

I haven't changed the place of the amps since original purchase and a lot of open space around.

Here's the Left amp, it's temperature at idle is a bit higher than the right one specially on both front sides.

Right Side AMp pictures to come separately.

[Katonoma]

Here are the Right side Images.

[James Tanner]

Hi Christian,

Ok - so the amps are running heat-wise as they normally would with the cable disconnected?

james

[Katonoma]

Hi Christian,

Ok - so the amps are running heat-wise as they normally would with the cable disconnected?

james

Sorry James, what do you mean by heat-wise?

[James Tanner]

Hi Christian,

Ok - so the amps are running heat-wise as they normally would with the cable disconnected?

james

Sorry James, what do you mean by heat-wise?

Sorry - is the temperature of the amps at idle similar to what they were when you were using your old cables?

james

[Katonoma]

Hi Christian,

Ok - so the amps are running heat-wise as they normally would with the cable disconnected?

james

Sorry James, what do you mean by heat-wise?

Sorry - is the temperature of the amps at idle similar to what they were when you were using your old cables?

james

James,

Well this I can't say for now since I haven't made measurements with the old cables because I don't have them with me  today.

I noticed the unusual heat dissipation this morning

What I can say right now is that both amps run about 3-4 degres hotter now that I've connected them with the TARALABS speaker cables (Volume level is quite low (Knob about 8 o'clock) Room temp is 21?C .  )

[James Tanner]

Hi Christian,

Ok - so the amps are running heat-wise as they normally would with the cable disconnected?

james

Sorry James, what do you mean by heat-wise?

Sorry - is the temperature of the amps at idle similar to what they were when you were using your old cables?

james

James,

Well this I can't say for now since I haven't made measurements with the old cables because I don't have them with me  today.

I noticed the unusual heat dissipation this morning

What I can say right now is that both amps run about 3-4 degres hotter now that I've connected them with the TARALABS speaker cables (Volume level is quite low (Knob about 8 o'clock) Room temp is 21?C .  )

Hi Christian,

Ok lets see what happens when you install your old cables.  Around 50C is reasonable for the 28B's but we can reset the bias a little lower if you wish.

james

[Katonoma]

Right AMp temp now:



Left Amp, remains still 7 degrees hotter.



What will happen this summer  & at louder volume levels??? 

[James Tanner]

I think we should have the bias reset for you.

james

[James Tanner]

I think we should have the bias reset for you.

james

Hi,

I contacted JBK (our distributor in France for you) and sent him all the correspondance to bring him up to speed.

james

[Katonoma]

Hi James,

Can you explain bias adjustment precisely.

Will this affect the sound of the amps?

[James Tanner]

Hi James,

Can you explain bias adjustment precisely.

Will this affect the sound of the amps?

I will get you a detailed explaination from Engineering.

james

[James Tanner]

Bias in this case is a standing or idling current that runs in the output transistors of a power amplifier.  It keeps the transistors in a slightly 'on' condition to prevent dead zones in the transfer function as the power transistors hand off from positive to negative polarity, or the opposite. Dead zones like that are the cause of what is termed 'crossover distortion', and it causes IMD and THD with higher-order harmonics. This can cause an amp to sound 'zippy' or grainy.

Bryston amplifiers are biased at a moderate current to give the smoothest possible transfer function, and reduce crossover distortion to essentially zero.  That is why Bryston amplifiers run somewhat warm to the touch even at no signal.

CWR