Amp layouts, courtesy of BillyBatz

Billy Batz · Post by **Billy Batz** » Tue Jan 17, 2006 5:14 pm

You get around I see.

Billy Batz · Post by **Billy Batz** » Thu Jan 19, 2006 11:28 pm

The first 69' 19959 layout I did was time consuming. Since then its just been modifying that one graphic and many times I did it fast. I dont think theres many actual electonic mistakes but there are deviations from the way marrshall layed out things. If you havent noticed already the first reply on this thread on page 1 is a log of mistakes fixed, mistakes left to fix and when the last update was. You may want to check that out.

Billy Batz · Post by **Billy Batz** » Sat Jan 21, 2006 3:59 pm

Updated the files again today. Thats all the mistakes left that I know about.

If anyone has the 67-68 file saved can you please send it to me?

MacGaden · Post by **MacGaden** » Sat Jan 21, 2006 4:38 pm

Did you get the old version of the 67-68 layout yet ? I have it.

Billy Batz · Post by **Billy Batz** » Sat Jan 21, 2006 5:02 pm

Yes I got it. Thanks mac.

Billy Batz · Post by **Billy Batz** » Sun Jan 22, 2006 10:19 am

Added a layout for a 2550 upon request

Guest · Post by **Guest** » Sun Jan 22, 2006 9:06 pm

Hi everyone. I've been lurking for a bit. Great forum!

Question about the 2203 layout. Does yours refelect the MV which used the 6550 Power Tubes or the EL34?

Billy Batz · Post by **Billy Batz** » Sun Jan 22, 2006 9:26 pm

Theyre the same amp as far as I know. There may be a change in the value of the bias pot resistor. I dont think you would change anything else though. 1K screen-grids I think with 6550's as well. Maybe the OTs int hose amps were made for 6550s? Different impedance? Even if that is the case people use 6550's with these amps even though the OTs are for EL34s.

wdelaney72 · Post by **wdelaney72** » Sun Jan 22, 2006 10:17 pm

According to Dave at Legendary Tones, Marshall used the 6550 for US MV because they were more durable, and EL34 for the rest of the world. I would guess it would have only been cost effective to do so if the rest of the components were the same. I'm sure the bias would have to be adjusted, though.

Thanks for your help.

Flames1950 · Post by **Flames1950** » Mon Jan 23, 2006 6:17 am

Billy Batz wrote:Theyre the same amp as far as I know. There may be a change in the value of the bias pot resistor. I dont think you would change anything else though. 1K screen-grids I think with 6550's as well. Maybe the OTs int hose amps were made for 6550s? Different impedance? Even if that is the case people use 6550's with these amps even though the OTs are for EL34s.

The 6550 amps got not only a bias resistor change at the distributor, but also got 150K splitters instead of 220K's. (Actually I think the official way at the distributors had two resistors that changed -- the one before the bias diode changed as well.....)

Billy Batz · Post by **Billy Batz** » Mon Jan 23, 2006 10:17 am

Yeah thats right. I forgot about the bias feed resistors. Know what the bias range resistors were changed to?

wdelaney72 · Post by **wdelaney72** » Mon Jan 23, 2006 10:39 am

Found this on Clay Finley's site...

"Also the 70's Marshalls saw different bias splitter values. 82K, 100K, 150K and the common 220K. The smaller values will load down the preamp and roll off the top end. The 82K/100K was usually used when 6550's came stock in the amp. A lot of people had the 6550's switched over to EL34's and most techs didn't change the bias splitters which resulted in a little more preamp crunch and a "browner" sound to the top end. The 220K's are the classic value for use with EL34's."

rockstah · Post by **rockstah** » Mon Jan 23, 2006 11:43 am

where does the 150k come in?

Billy Batz · Post by **Billy Batz** » Mon Jan 23, 2006 11:44 am

In place of the 2 220k's

rockstah · Post by **rockstah** » Mon Jan 23, 2006 11:46 am

interesting

Metropoulos Forum

Amp layouts, courtesy of BillyBatz

Early 2203