View Single Post
  #1 (permalink)  
Old October 30th 04, 09:38 PM posted to uk.rec.audio
Keith G
external usenet poster
 
Posts: 7,388
Default Bias adjustment II - 'The Reckoning'

Apologies for the delay for this 'joint reply' - interrupted by a little
post-prandial 'digestif' by way of a spot of Delius and VW (Larka Sending
and Symphony No. 6 - still playing! :-)

*Massive thanks* to *all* who responded and were, between you, just about
right on the money, from what I can see of it!! (Fekkin' valvies - too damn
sad/skint to be out on the ****/tiles/razzle on a Saturday Night!! :-)

(I dunno!!)

OK. First up, the valves read as follows (Test voltage, amp on / Resistance,
amp off - the DVM wuz under me bed!!)

V1 = 0.317 V / 10.2 ohms (10R2 ??)

V2 = 0.303 V / 10.0

V3 = 0.322 V / 10.2

V4 = 0.318 V / 10.5

(I'll check tomorrow, but I thought the voltage readings were all "+" ???)

Next, the valve labels are all as follows:

http://www.apah69.dsl.pipex.com/keit.../valvebase.jpg

Now, call me a bluff old cove, but this looks to me a bit like we want
is -37 VDC on the grid (am I right?) - ie. the 'test' voltage?? If so the
valves are all(consistently) 'underbiased?

What do each of these figures mean? (I understand about the valves being
'matched' but I thought was mA / V or summat??)

Many thanks, once again.