50 Watt voltages?

franc · Post by **franc** » Tue Nov 21, 2006 4:59 pm

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.

Andy · Post by **Andy** » Tue Nov 21, 2006 9:03 pm

Check here:

http://members.shaw.ca/house-of-jim/Html/Marshall.html

-Andy

franc · Post by **franc** » Wed Nov 22, 2006 10:10 am

Thanks,

Any suggestions as to what those voltages should be like without tubes installed?

novosibir · Post by **novosibir** » Wed Nov 22, 2006 3:51 pm

5% - 10% higher, with small PT's sometimes even 15%, depending on the PT's sponginess.

Larry

5150loveeddie · Post by **5150loveeddie** » Thu Dec 14, 2006 3:36 pm

Is 385vdc on the B+ a little low for a 1987 head?? Seems to not have the punch it should, etc.....

novosibir · Post by **novosibir** » Fri Dec 15, 2006 3:30 am

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

5150loveeddie · Post by **5150loveeddie** » Fri Dec 15, 2006 8:58 am

Go to know Larry, thanks so much!!

imo · Post by **imo** » Sun Feb 11, 2007 12:42 am

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

Flames1950 · Post by **Flames1950** » Sun Feb 11, 2007 12:53 am

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.........

imo · Post by **imo** » Sun Feb 11, 2007 2:20 am

that would make sense then..I will try that and report back..thanks!
Ian

Metropoulos Forum

50 Watt voltages?

50 Watt voltages?

50 watt dc voltage no tubes too high