Does dual bias really work to 'Match' tubes?

[Willabe]

Timbo now that I can open your file drawings, no I don't think that will work.

I think that will mess with the bias. I think the PPIMV should be tied in before the -bias grid leak and power tube grid stopper.

I'll be right back with a drawing.


            Brad    

Edit; I'm wrong on this as explained latter, sorry Timbo, guys .

[Willabe]

Thanks Ed, and yes guys I have a PC.


            Brad     

[Willabe]

Like this.

(Yes I left out the R's across the MV pots but you get the idea.)


                  Brad    

[Willabe]

Sorry, Sluckey types too fast

Yes he does.


         Brad     

[TIMBO]

And brad this is why you are good at building valve amps and when there is a computer problem you call the "guy"  well that is what I do and after he slugs you a pile of bucks, one can only hope that one day he comes knocking on YOUR door for and amp repair  COMPUTERS 

[Willabe]

Yes.


         Brad     

[TIMBO]

Hey Brad, I have used the PPIMV with a fixed and haven't had any problems, so this is why I drew it like this as I can't see that it would change anything when adding the dual bias

[Willabe]

I might be wrong Timbo.

But the way you have it drawn it will have the -bias dc on the MV pot, so it will be scratchy sounding.


           Brad    

Edit; I am wrong on both statements as explained latter, sorry Timbo and guys.

[TIMBO]

I will certainly give your circuit a try. Thanks

[sluckey]

But the way you have it drawn it will have the -bias dc on the MV pot, so it will be scratchy sounding.

There's no bias current flowing thru the MV pot so it will not sound scratchy. That circuit works fine. Remember, the bias supply looks like AC ground because of the filter caps.

[PRR]

> Download Timbo's "DUAL FIXED BIAS with PPIMV.sch" file to your desktop. Right click on the file and select 'Open with...'.

I'd rather have another icon on the desktop than clutter the file-association hack.

I keep JSchem.exe on the desktop. Download SCH file to desktop, drag it on top of JSchem, it opens.

Diff'rent strokes. Just sayin'.

[Willabe]

There's no bias current flowing thru the MV pot so it will not sound scratchy.

Ok, I was wondering about that, I remember you talking about that before. So Timbos good to go then.    

That circuit works fine. Remember, the bias supply looks like AC ground because of the filter caps.

Ah, Ok just like the B+ rail see ac ground through the filter caps. And it saves a pair of coupling caps.


           Brad    

[Willabe]

I'd rather have another icon on the desktop than clutter the file-association hack.

I keep JSchem.exe on the desktop. Download SCH file to desktop, drag it on top of JSchem, it opens.

I'll try that too as I keep SCH on the desktop already, thanks.


                  Brad     

[sluckey]

I'd rather have another icon on the desktop than clutter the file-association hack.

I consider file association a feature, not a hack. I especially like it for files on the net such as .sch that I want a quick look without the clutter of actually downloading to a folder and having to delete after I took a quick look.

When I click on a sch or pdf file or etc., I have a choice to download or open. If I want to save it, I download. If I just want a quick peek, I choose to open it and the file downloads to my temp internet files folder and opens in ExpressSCH, Acrobat, or whatever. And I don't have to clean up the crumbs afterward. Seems more convenient to the way I use a computer.

[TIMBO]

 

[Ed_Chambley]

All of the mentioned ways of opening files have validity.  I use all of then for different reasons.  I never considered file association a hack either.  I am sure PRR has a valid reason for using the word hack.

I like to do the peek and see thing, but most times I need something to compare the question.  The longer I am at this (old timey electronics) the less I compare too.  After a while all the amps begin to look strangely similar.

I laugh every time HBP states all amps sound very similar at low volumes.

My "For Review" folder has been very beneficial.  With dual monitors I can compare schematics quickly without the need for printing them. 

[Willabe]

With dual monitors I can compare schematics quickly without the need for printing them.

Hey, no fair.


           Brad