Halo A21 bias adjustement

[Zoran]

Hi all,

I can see that the left channel of my Halo A21 goes slightly warmer than the right one - difference not too prominent, but still detectable even by a naked hand. I measured approx. 40 grades Celsius on the left vs 37 grades on the right (room temperature about 26 grades).

Is that a problem? Does this indicate some bias disbalance between two channels?

If so, how to manage it? No service manual available to see the factory values, etc... I am not skillful enough to operate anything inside without service manual.

Does someone own the Halo A21 service manual?

[Zoran]

Kudos To Parasound Service Team!

Tom At Parasound Customer Care Service Kindly Sent Me All Required Info Including Segments Of Shematics... Wonderful!!!

Parasound Customer Care Remains The Top One!

[Vince Helm]

Kudos To Parasound Service Team!

Tom At Parasound Customer Care Service Kindly Sent Me All Required Info Including Segments Of Shematics... Wonderful!!!

Parasound Customer Care Remains The Top One!

Hey Zoran,

Great news and great job parasound!!!!! Please let us know what the problem was and the fix.

Kind regards
Vince

[Jesse111]

I don't even want to know if my amps run at the same temp or not. If I was to find out there was a few degrees difference It'd bother me everytime I sat down to listen. I'd start hearing (or not hearing) things from which ever amp I thougt was in some way. Psychoacoustics is where that would lead for me.

Does Parasound offer specs on heat? Is there a range of degrees that the amps can be and still be within specs?

But I'm with Vince. Let us know what you find out.

[Peter Nielsen]

Does Parasound offer specs on heat? Is there a range of degrees that the amps can be and still be within specs?

Heat = idle bias current.

A good approximation is to just check the 120V AC current draw at the power cord. Yes, JC-1s vary slightly.

Peter

[Peter Nielsen]

Hi all,

I can see that the left channel of my Halo A21 goes slightly warmer than the right one - difference not too prominent, but still detectable even by a naked hand. I measured approx. 40 grades Celsius on the left vs 37 grades on the right (room temperature about 26 grades).

Is that a problem? Does this indicate some bias disbalance between two channels?

This does not necessarily indicate a problem. This could simply be a result of how the amplifier is placed in the room.

Is there any assymmetry? Is there any equipment close to the amp on either side, any difference? How is the air conditioning in the room? Is there a chance that one of the sides has more movement of air?

Measuring the actual bias current inside the amp is the only way to be sure. The temperature difference could simply be caused by the enviromnent. Maybe one side is better cooled by circumstance...

Peter

[Chris D]

Yes, very interested in what Parasound tech support had to say!

[Zoran]

This does not necessarily indicate a problem. This could simply be a result of how the amplifier is placed in the room.

Is there any assymmetry? Is there any equipment close to the amp on either side, any difference? How is the air conditioning in the room? Is there a chance that one of the sides has more movement of air?

Measuring the actual bias current inside the amp is the only way to be sure. The temperature difference could simply be caused by the enviromnent. Maybe one side is better cooled by circumstance...

Peter

No any assimmetry Peter. The A21 well clear from everything arround (walls, furniture...etc). No clima or anything else which may contribute the heat dissbalance between two sides.

It is (minor) inherent problem, some subtle difference between two moduls (Tom at Parasound said so).

Of course, I'll let all of you know the result of bias readjustement...