Parallel effects loop for Marshall style amps

joshwilson3 · Post by **joshwilson3** » Wed Jun 06, 2007 1:58 pm

I don't remember if this has been mentioned before. But Larry, is there any particular 12AX7/ECC83 tube you like to use for the FX tube? RFT, Tesla...?

novosibir · Post by **novosibir** » Wed Jun 06, 2007 3:09 pm

7string wrote:A long shot but, what about the 12au7. Any chance of them working in this circuit? I need to find a place for a few.

Only because you have them laying around, you shouldn't try to stick them anywhere

Buy a VOX or a Seymour Duncan Convertible, there you may stick one in each - but in this loop it doesn't work.

Larry

novosibir · Post by **novosibir** » Wed Jun 06, 2007 3:14 pm

joshwilson3 wrote:... is there any particular 12AX7/ECC83 tube you like to use for the FX tube? RFT, Tesla...?

No, there's no particular type! You may choose, what you like soundwise, because that's of course an additional place, where you may obtain slightly different tone shapes with different tube brands!

Larry

5150loveeddie · Post by **5150loveeddie** » Thu Jun 07, 2007 9:19 pm

Hi Larry, when it says "to PI input Cap (.022u)... run the wire from the socket to that .022uf cap? you connect that wire on the "Pots" side? Not the the "tube side" of that cap right?

The voltages connections between the 4k7. it says B+3, that one goes to the PI filter cap's plus lug or where it meets on the board?

And the other side can we connect it to the plate resistor turret where the voltage comes from (via the 10k/filter cap under the board)?

My loop is located on the left side completly.....

Danke LArry

novosibir · Post by **novosibir** » Fri Jun 08, 2007 6:11 am

1) Shure pots side, otherwise there's no decoupling!

2) B+3 = PI's voltage supply, no matter where you connect it to!

3) Question don't understand!

Larry

5150loveeddie · Post by **5150loveeddie** » Fri Jun 08, 2007 9:38 am

novosibir wrote:
3) Question don't understand!

Larry

The other voltage supply, where it comes from? Can I just connect a wire to the junction of the 10k 2watt with the filter cap under the board?

BTW I swap by mistake the 22uf with a .22uf instead, made the amp with no sustain and a funny but hugly tremolo induce type effect!!

Thanks LArry

novosibir · Post by **novosibir** » Fri Jun 08, 2007 3:10 pm

5150loveeddie wrote:The other voltage supply, where it comes from? Can I just connect a wire to the junction of the 10k 2watt with the filter cap under the board?

Which other voltage supply and which 10K/2W? There are a few voltage supplies and a few 10K/2W in the amp!

Sorry, but I can't find into your thoughts!

Larry

5150loveeddie · Post by **5150loveeddie** » Fri Jun 08, 2007 3:24 pm

novosibir wrote:
5150loveeddie wrote:The other voltage supply, where it comes from? Can I just connect a wire to the junction of the 10k 2watt with the filter cap under the board?
Which other voltage supply and which 10K/2W? There are a few voltage supplies and a few 10K/2W in the amp!

Sorry, but I can't find into your thoughts!

Larry

Sorry, have a poor English vocabulary............ What I mean is..., where it says (on the ptp diagram) "20u filter" (from one side of the 4k7 resistor), how exactly is that connection made?

novosibir · Post by **novosibir** » Fri Jun 08, 2007 3:58 pm

The side of the 4.7K, where the 20

5150loveeddie · Post by **5150loveeddie** » Fri Jun 08, 2007 6:18 pm

[quote="novosibir"]The side of the 4.7K, where the 20

jngreene79 · Post by **jngreene79** » Fri Jun 08, 2007 6:31 pm

Use any spare cap you have if it's in the amp already. This loop is in my amp and I've got a 10uf and different dropping resistor. It sounds great. I wouldn't worry too much about the small stuff not in the signal path. But, that's just me and my experience (that is dwarfed by Larry's) -James

novosibir · Post by **novosibir** » Fri Jun 08, 2007 6:47 pm

5150loveeddie wrote:That 20u is located on the board in the jtm45 right? I could use one of the plus side of my 33+33uf cap mounted under the board, on top of the chassis?

If you do have a yet unused spare cap in the amp???

Larry

5150loveeddie · Post by **5150loveeddie** » Sat Jun 09, 2007 12:54 pm

Ah I see, we must add that 20uf right????

novosibir · Post by **novosibir** » Sat Jun 09, 2007 1:23 pm

5150loveeddie wrote:Ah I see, we must add that 20uf right????

Bingo!

5150loveeddie · Post by **5150loveeddie** » Sat Jun 09, 2007 1:35 pm

Danke!