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50 Watt voltages?
Posted: Tue Nov 21, 2006 4:59 pm
by franc
Probably already scattered all over the place, but what are correct voltages with and without tubes for a 50Watter? About the same as a 100W?
Might be nice to summarize here.
Posted: Tue Nov 21, 2006 9:03 pm
by Andy
Posted: Wed Nov 22, 2006 10:10 am
by franc
Thanks,
Any suggestions as to what those voltages should be like without tubes installed?
Posted: Wed Nov 22, 2006 3:51 pm
by novosibir
5% - 10% higher, with small PT's sometimes even 15%, depending on the PT's sponginess.
Larry
Posted: Thu Dec 14, 2006 3:36 pm
by 5150loveeddie
Is 385vdc on the B+ a little low for a 1987 head?? Seems to not have the punch it should, etc.....
Posted: Fri Dec 15, 2006 3:30 am
by novosibir
5150loveeddie wrote:Is 385vdc on the B+ a little low for a 1987 head?? Seems to not have the punch it should, etc.....
There are some out with that low B+, but that's rather seldom!
Very smooth and creamy sozunding, although not too much punchy, right!
I've found those even w/ only 82K bias feed resistors instead of the usual 220K's
Larry
Posted: Fri Dec 15, 2006 8:58 am
by 5150loveeddie
Go to know Larry, thanks so much!!
50 watt dc voltage no tubes too high
Posted: Sun Feb 11, 2007 12:42 am
by imo
I just installed the 50w plexi ptp bpard, replacing a PCB from a reissue. Pretty sure everything is in order and its right place. I fired it up and was getting pretty much the same voltage all through the B+, with no drops on the resitors. It was hovering around 460v DC all the way to the plates of V1. This was without the tubes in. I tried 2 different ground references to make sure i had a solid one both caps ground near the Ac inlet and fuse) and they both reported near the same. My bias circuit seems fine, @-30v with no adjustment. I also noticed that the DC drain was particularly slow as well. Inching down, whereas on my 100w it drains quite a bit faster. There were some different wiring diagrams on the cd that came with the kit, but i used the guide that had the Metropolous amp logo at the top(50 watt) as well as double checking with the schematic. It seems to be in line. I checked all reisitance values, as well as checking continuity between board components and their destination spots..
Any ideas on what to look to? Is it possible that the tubes would pull the voltage down to a correct level?
Ideas and suggestions would be very gladly fielded!
thanks
Ian
Posted: Sun Feb 11, 2007 12:53 am
by Flames1950
Yes, you need to at least put in the preamp tubes to get your voltages down in line with the charts!!!
With no tubes at all in the amp, you're not flowing any current at all, so the voltages never drop.........
Posted: Sun Feb 11, 2007 2:20 am
by imo
that would make sense then..I will try that and report back..thanks!
Ian