From mgarvi–(at)– Tue Apr 23 12:03:35 CDT 1996
Article: 8823 of
From: mgarvi–(at)– (Mark Garvin)
Newsgroups: alt.guitar.amps,
Subject: Re: More help: Where to measure bias?
Date: 23 Apr 1996 01:51:11 -0400
Organization: PANIX Public Access Internet and Unix, NYC
Lines: 33
Message-ID: <4lhr4f$b1--(at)>
References: <3173B509.794--(at)> <4l0u20$19c--(at)> <31765AE7.167--(at)> <4l6oo0$u5--(at)>
Xref: alt.guitar.amps:13493

In cign–(at)–elios.phy.OhioU.Edu (Dave Cigna) writes:
>I prefer a one ohm resistor in the cathode circuit too, but you guys seem
>to be missing the fact that in any case, if you have screen grid resistors
>in place, then you can measure the voltage drop across them and calculate
>the screen current. A little arithmetic never hurt anyone.

I just read thru most of this thread and I was wondering when someone
was going to mention this. Your amp had better have screen resistors, so
measure the voltage across ’em and make note of it. Even if they change
a bit, the deviation will not form a large percentage of the overall cath.
current. So…the high voltage stuff can be checked once and done with.

At that point you can provide 1 ohm resistors with chassis-mounted jacks
so the amp’s owner can monitor the bias with a Radio Shack meter without
acquiring a Don King hairdo.

– – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – –

Regarding the ‘quality of the news group’:
What if you bought a book that was supposed to be about guitar amps,
but was in reality a lot of mindless bitching about Kurt Cobain?
I think those in this group have a right to expect posts being close
to topic. Otherwise, why would anyone with reasonable technical
skill want to pay be here?

– – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – –

And last…
My compliments, Mr. Cigna, on the cool tone control response program.
Good work.

Mark Garvin


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