[95Dyna]

I just installed a new pair of 7BSSTsq about a week ago.  So far I'm very pleased with their performance especially after installing the BP26P a week later.  One thing does puzzle me, however.  The right channel operates and idles noticably warmer than the left.  At first I thought of swapping sides to see if inconsistent speaker loads or cable performance was the cause but this occurs while they are idling with the preamp turned off.  They are both plugged in to the same 15 amp circuit.  These amps do not break a sweat no matter how hard they are pushed so we are talking about the difference between warm and lukewarm here.  Any ideas out there as to why this is happening.  I'm hoping I don't need a bias adjustment.

Regards, Bill

[James Tanner]

Hi Bill,

Each amp is hand tuned and the 'bias' is adjusted independently on each amp to optimized the performance. So the temperature will vary from amp to amp depending on the specific bias settings.

james

[Mad Mr H]

temp can vary just by room position as well......

Near a door, a window, in sunlight, in shade, over a pipe in the floor, in airflow, close to wall, close to radiator!

Etc.

You could swop them round to see if the same is still hotter, But like James says if its running fin and sound great thats all that matters.

If it is WAY different - too hot to touch vs luke warm then I would be concerned.

Andy.

[werd]

Hey Dyna

Nice job on the 7B's. You say one is slightly warmer than the other...hmm. and James says its could be a bias issue. Try running a fan on the warmer one and see if it cools off. Fan cooled wont do much for coolin off a warmer unit due to biasing. If it does cool it would say to to me there are other issues, perhaps something that the mad hatter mightve mentioned above.

[95Dyna]

Thanks James and Andy,

The placement circumstances are identical.  The thermal range is from slightly warm on the left to warm on the right at idle.  Its interesting that in most of the applications deployed thus far that the heat dissipation levels don't increase that significantly and the difference seen at idle remains constant as load increases.  Even when pushed hard with bass oriented output they don't get anywhere near too hot to touch.  My speakers are Infinity 9 Kappas which have been known to be very amp unfriendly and for the 7's to handle them during a heavy load without getting hot to touch in either channel is quite impressive. 

Does this differential indicate the right channel amp is running in class A longer than the left channel (assuming bias settings are different in two amps)?  I'm still not sure I understand why the bias settings would be different in two identical mono blocks especially with consecutive serial #'s.

[Sasha]

I find this to be the case as well, and not only between amps but between heatsinks on single 7B.

[Mad Mr H]

Hi,

Rather than checking for heat with hand I would suggest temp probe.

Also - dont think me rude here (and I DONT know your room) but can to be 100% sure the air flow in the room is identical in each location?

As you can't see airflow?
Just curious?


It is worth checking that there are no hairs of speaker wire out of place at either end - I totally doubt in this case thats anything to do with the heat but always worth checking.

I would prefer to hear temps from a probe  in this kind of thread.

[95Dyna]

Hi,

Rather than checking for heat with hand I would suggest temp probe.

Also - dont think me rude here (and I DONT know your room) but can to be 100% sure the air flow in the room is identical in each location?

As you can't see airflow?
Just curious?


It is worth checking that there are no hairs of speaker wire out of place at either end - I totally doubt in this case thats anything to do with the heat but always worth checking.

I would prefer to hear temps from a probe  in this kind of thread.

I'll check the actual temps this evening.  The air flow should be the same from both amps as they are sitting in identical spaces inside a 24" x 24" cabinet with 8" clearance above, 3.5" on each side and 8" to the rear.  the front is open.  There are no heat generating units on the shelves above.  Speaker wires are properly terminated with bannana plugs at each end.  I would have no way to actually measure air flow so the thing to do would be to swap the amps locations/connections.  Thanks for your input.

[95Dyna]

The actual temperature differential is about 6C (12F).  I swapped the amp locations leaving the cables in place and the recorded temperatures remained in the same locations with the same differential so it's not the amps causing it.  The shelf spaces for the two amps are not a variable as they are identical so I'll focus on the cables starting with the SC's.

[srb]

Assuming the cables check out OK, it is more likely that it is variations and tolerances between speaker drivers and/or crossover components as the load they present to the amps.
 
Switching speakers on the amplifiers will reveal if that is the case.
 
Steve

[95Dyna]

Assuming the cables check out OK, it is more likely that is variations and tolerances between speaker drivers and/or crossover components as the load they present to the amps.
 
Switching speakers on the amplifiers will reveal if that is the case.
 
Steve

Thanks, Steve.  Maybe I should just cut this short and tell my wife if I don't get new speakers right away they will destroy my brand new amps.  When I begin to explain how resistance variables between speakers present different loads to the amps she'll beg me to get lost and go speaker shopping .

[predrag]

I have a pair of 7B SSTsq as well. As they are positioned one above the other in an open rack and there is a temperature difference of around 5 degrees C.
The upper one is always warmer as warm air flows upwards form the lower positioned one .
When I get dedicated amp stands to positon them adjacent to speakers the temperature will be equal.
With my pair of 7B SSTsq so far so gooood! 

[racerxnet]

My speakers are Infinity 9 Kappas which have been known to be very amp unfriendly and for the 7's to handle them during a heavy load without getting hot to touch in either channel is quite impressive.

 Are you running the Kappa 9's in the extended mode or normal. Is the toggle switch on the back side in  the same position for both speakers? Maybe this is the cause of the temp difference... One position normal and the other extended. I have run my Kappa 9's in the extended mode and can say the Brystons will take the beat'in I put on them. The switch is under the round black plastic cap next to the crossover pots.

MAK

[95Dyna]

My speakers are Infinity 9 Kappas which have been known to be very amp unfriendly and for the 7's to handle them during a heavy load without getting hot to touch in either channel is quite impressive.

 Are you running the Kappa 9's in the extended mode or normal. Is the toggle switch on the back side in  the same position for both speakers? Maybe this is the cause of the temp difference... One position normal and the other extended. I have run my Kappa 9's in the extended mode and can say the Brystons will take the beat'in I put on them. The switch is under the round black plastic cap next to the crossover pots.

MAK

Hi racer,

What a delight to hear from another 9 Kappa user.  I don't keep the caps on the bass attenuation switch for ease of access.  I almost always keep them in the extended position as it sounds much better overall.  As you pointed out, the 7B's have not broken a sweat despite the notorious low frequncy dip to .8 ohms these speakers present.  My test CD for this situation is by The Afro-Celt Sound System, a song called "Whirly Wheel".  If you can't fry an egg on the amp after playing this piece through a pair of 9 Kappas your doing good.  The 7's just get a little warm and the LED stays a solid green throughout.


Regards,

Bill

[racerxnet]

 
Bill,

My Kappa's are up for sale at Audiogon. (Nice plug Eh) Anyhow, I am using the 7BST's to power my RS1B's at this time. It's not to bad on the impedance compared to the 9's. The 9's still can hold their own against many higher priced offerings. Just because they are old does not mean newer is better. You can see pics in my gallery.

MAK

[95Dyna]

I have a pair of 7B SSTsq as well. As they are positioned one above the other in an open rack and there is a temperature difference of around 5 degrees C.
The upper one is always warmer as warm air flows upwards form the lower positioned one .
When I get dedicated amp stands to positon them adjacent to speakers the temperature will be equal.
With my pair of 7B SSTsq so far so gooood! 

Hi predrag,


Have you swapped the amp positions keeping the cables the same to see if the warmer amp is still the one on top?  In my situation there is nothing below the upper amp to allow warm air to ascend into its shelf space so I have ruled out shelf position as the cause.  Great to hear from you

Bill

[predrag]

Hi Bill,

Yes of course I tried swapping their position and the same thing happens: Upper one is slightly warmer. Normal situation that does not affect their function.
Do you have photos of your system? You can have a look to my photoalbum and see what I?m talking about.
Good luck!