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-   -   Beard P35 and Tubes Replacement (http://www.diyaudio.com/forums/tubes-valves/104785-beard-p35-tubes-replacement.html)

greytear 6th July 2007 09:09 PM

Beard P35 and Tubes Replacement
 
Dear all:

As a newbye to this forum, why would like to post a very simple question/ask for recommentation:

Recently i became a happy owner of a Bear P35 Power Amp, which uses 6 EL84 as power tubes (per channel) and two ECC81's as drivers.

Although the "original" tubes (a mixture of RSD and tronal) were in a good condition, i bought 2 matched sextets of brand new tronal tubes. As the moment i'm writing this post, they keep going on its burn-in stage. Well, the sound is not so good as previously, but i believe the typical 100 hours burn-in period for the tubes to sound their best. Could I possibly be right?

Another thing that keeps me curious deals with bias adjustment. Does anyone knows if this amp has a self-adjusting bias circuit? Should I be worried about checking bias regulation? Would it be too much if i ask for some guidelines? ((begginer here, I'm sorry...)

Is it "normal" that although the tubes are all alike, some of them glow much than others (however the "glow" is simmetrically distributed among both channels)?

Thank you all for your patience
Best regards

liberty 7th July 2007 03:58 PM

Here is a link to an italian 3D.
Since you come from Portugal you can translate it easly(I guess):

http://edonismo.webpal.info/phpBB2/viewtopic.php?t=62

Tube_Dude 8th July 2007 03:51 AM

Re: Beard P35 and Tubes Replacement
 
Quote:

Originally posted by greytear


Another thing that keeps me curious deals with bias adjustment. Does anyone knows if this amp has a self-adjusting bias circuit? Should I be worried about checking bias regulation?



Olá Vizinho! :)

Don't worry about the Bias of the Beard P 35 .

The bias is automatic and is provided by a 3 pins integrated voltage regulator 7805 ,connected as a CCS (constant current source).

Quote:

Is it "normal" that although the tubes are all alike, some of them glow much than others
Yes, it depend of tolerance in construction of the tubes , some have the heaters more exposed than others.

Don't worry about that and enjoy the sound .

Abraço

greytear 11th July 2007 10:45 PM

Well....thing are getting quite sad, here...

I just opened the machine and saw that something's not as good as I expected. Some 7805's had soldered joints (the previous owner, probably, had the machine repaired, and the pins got broken...i guess), but the most intriguing thing was that some capacitors were replaced (three or four of them).

Can anybody suggest a good 1000 uF replacement capacitor for the machine? I read a lot about black gate capacitors, but....i wonder if it worths the money. Checking the bias schematics, i would like to ask you: is it a good idea to replace the caps by 50 V capacitors, or should i stick to 35 V ones?

Thank you
Luis

iconserv 30th September 2010 09:40 PM

Hi

Here is a question directed at Tube_dude who seems to have some knowledge of the Beard amps - I have just bought two M70 MKIIs. They drive my Quad ESL57s very well.

I have an idea of rebuilding a second set of ESL57s and having stacked QUADS - as the M70 is basically a P35 with what looks like a simple wire bridge at the input and output sockets - I assume that by simply removing the bridge at the two pairs of speaker terminals I can effectively turn them into stereo amps with a shared input. I just want to confirm with you that this is the case and that it shouldn't cause problems.


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