Hey rockstah - filtering...

ABR-1 · Post by **ABR-1** » Sat Mar 11, 2006 1:27 am

In my opinion the low screenfiltering(16uF) is a BIG key to the sound of these amps.I used double 32´s but i only used one section on each can for a total of 16uF.You could of course use double 16´s wired as stock in parallell/serie but the outside diam. of these cans wont fit the clamps on the chassie,(at least not the ones i´ve seen)

ABR-1 · Post by **ABR-1** » Sat Mar 11, 2006 3:41 am

After second thoughts,i think the German made F&T 16+16uF will fit into a standard clamp.

Shredder · Post by **Shredder** » Sat Mar 11, 2006 10:44 am

Yes they will, because I've got one installed in the pre-amp section already.

rockstah · Post by **rockstah** » Sat Mar 11, 2006 12:20 pm

i have 16+16 F&T can thats the same size as my dual 50+50 f&t cans.

Crunchboy · Post by **Crunchboy** » Wed Mar 22, 2006 9:55 am

ABR-1, I would greatly appreciate it if you could list the changes you made to MK's RI to make it like his '68 in a way that a decent tech (like yourself) could read. I'd like to do this to a reissue just like you guys did but I don't really "get" most of this tech talk. Excluding the OPT and tubes, please list the other changes like NFB circuit, filtering, etc. Thanks.

ABR-1 · Post by **ABR-1** » Sat Mar 25, 2006 1:55 am

well,these 1959 SLP reissue amps are very similar to the original 67-68 SL that MK owns ,split cathod with 820/.68 on V1b ,.68 bypass cap on V2a ,same kind of power section with only one 1,5 kohm gridstopper res. on each side.
http://www.drtube.com/schematics/marshall/1959spwm.gif
http://www.drtube.com/schematics/marshall/1959sprm.gif
we changed the filter section as stated previous in this thread,OT is a 2" ****** audio,all signal caps changed to Sozo original Mustards.
Second dropping resistor(R20) lowered to 8.2k for a little higher voltage on the pre amp section.
The only other changes is that we snipped the cap bleeding off high freq. after the tone stack(cap C21)and we added an other 47pF across the PI fizzy cap(C11) for a total of 94pF.We also changed the feedback wire to the 4 ohm tap.
Some really good ol NOS tubes as a last spice.
That´s about it!