Parallel effects loop for Marshall style amps

rockstah · Post by **rockstah** » Wed Dec 05, 2007 6:23 pm

novosibir wrote:In the version w/ true bypass switch are 2 2.2M resistors to avoid the switching pop.

Larry

which version is this?

Ivabiggun · Post by **Ivabiggun** » Wed Dec 05, 2007 6:33 pm

On the schematic Larry sent with the true bypass included it says
version 1.1.

Iva

rockstah · Post by **rockstah** » Wed Dec 05, 2007 6:36 pm

can u send me that schem - mark@markabrahamian.com - thanks

novosibir · Post by **novosibir** » Wed Dec 05, 2007 7:20 pm

Ivabiggun wrote:... but does 2M2 mean 2.2uf's? What voltage do you reccomend?

No, they are different animals!

2M2 is resistance, 2.2uF is capacitance.

Voltage rating for the 2M2 doesnt matter, all above 50v is ok.

Larry

rockstah · Post by **rockstah** » Wed Dec 05, 2007 7:40 pm

has the switch type been mentioned yet for the true bypass loop?

also wondering if these loops are using a 12at7 or a 12ax7?

rockstah · Post by **rockstah** » Thu Dec 06, 2007 12:54 pm

hey Larry,

as i have taken this on somethings come to mind. how does this loop work in a dimed plexi? it seems it wouldn't work that well and since its yours i figured you would know.

have you tweaked for this purpose?

Mark

novosibir · Post by **novosibir** » Thu Dec 06, 2007 1:13 pm

rockstah wrote:how does this loop work in a dimed plexi? it seems it wouldn't work that well and since its yours i figured you would know.

Have you tried it or do you just guess?

Tell me one reason, why it shouldn't work well in a dimed Plexi!

Larry

neikeel · Post by **neikeel** » Thu Dec 06, 2007 1:34 pm

All good questions!

I have a bare bones 100watt being slowly fleshed out on my bench in parallel with the 68 restoration.

I have put four preamp tube sockets in and cannot make my mind up whether to put the Bainzy mod as V0 or Larrys effects loop in as V4

I hate having my Electric mistress and DD3 in a front end loop

rockstah · Post by **rockstah** » Thu Dec 06, 2007 2:11 pm

novosibir wrote:
rockstah wrote:how does this loop work in a dimed plexi? it seems it wouldn't work that well and since its yours i figured you would know.
Have you tried it or do you just guess?

Tell me one reason, why it shouldn't work well in a dimed Plexi!

Larry

havnet tried it yet.. just wondering how it works in a dimed plexi. thats all.

jerrydyer · Post by **jerrydyer** » Sun Dec 16, 2007 4:17 pm

could i have noise problems if I am drawing my b+ from the wrong spot. I take it from the preamp 100k 100k juncture of the two first gain stages. thanx

novosibir · Post by **novosibir** » Sun Dec 16, 2007 5:14 pm

I've never tried it, because it's simply wrong, to take it from V1

Larry

J.DavisNJ · Post by **J.DavisNJ** » Mon Dec 17, 2007 5:26 pm

Question gentlemen,

Do you think this loop circuit board could fit beside the amp circuit board in a 100 watt chassis?? I'd like to do this eventually to a Superbass build.

Would there be any noise issues?

-Joe

Tuco · Post by **Tuco** » Mon Dec 17, 2007 10:21 pm

I have some noise in my loop in my JTM45, so I am re-routing some of the wiring. I am running the circuitry in a box on top, very similar to the box that Franc showed a couple of pages back. I have been running all the wiring into the amp chassis through two access holes. I will now expand that to four access holes: B+, heater wires, output to PI, and pot wires. My question is through which of these holes can I run all the loop's ground wires? Does it matter?

Also, can I do a star ground inside the loop box, and then run just a single ground wire into the amp chassis? If yes, can that star ground be attached to the loop box, or does this cause a bad ground loop?

TIA.

novosibir · Post by **novosibir** » Tue Dec 18, 2007 8:18 am

Tuco wrote:Also, can I do a star ground inside the loop box, and then run just a single ground wire into the amp chassis?

Yes.

Tuco wrote:If yes, can that star ground be attached to the loop box, or does this cause a bad ground loop?

Either the ground is on the box, but the box insulated from the chassis - or the box is grounded to the chassis and the circuit ground inside insulated from the box.

But the box MUST have a grounding, otherwise it doesn't shield anything and your loop section will be noisy.

Larry

Tuco · Post by **Tuco** » Tue Dec 18, 2007 9:42 am

Larry, thanks.

What about my other question. If I have a star ground inside the box, I will have six wires entering the chassis through four access holes: ground, B+, PI input, 2 heaters, and pot wires. B+, heater, PI, and pot wires all get their own hole. Can I pair the ground wire with any of these without noise problems? TIA!