Parallel effects loop for Marshall style amps

Ricky Lee · Post by **Ricky Lee** » Wed Mar 19, 2008 7:49 pm

jerrydyer wrote:thats killer how you intergrated th eloop onto that board. work of art there Ricky Lee.

Thanks. I had about 4 inches of space left between the main board and the far end of the chassis and that's exactly the dimension I needed to install the loop board and it's components. You really haft to look close to tell the loop board is separate from the main board. I just bought some phenolic board that's long enough to actually integrate the loop right on to the main board, which is what I'll do with my next build. Additionally I'll install the loop components right before the PI near v-2 and v-3. It takes about 14 inches of board to integrate the main and loop baord. George's BB board would probably be perfect for this.

DPSharky · Post by **DPSharky** » Sun Mar 30, 2008 2:49 am

Ricky Lee, I was looking at the pic you posted for the board you built, and I noticed that your Sozo Cap between the V3a cathode and the send jack is a .047K (473K) but Larry's schematic calls for a .47K (470n) minimum. I don't know if that may be contributing to the problem with it sounding bad, but it seems it could be something to consider.

Scott

DPSharky · Post by **DPSharky** » Sun Mar 30, 2008 2:55 am

oops... meant uF not K

Ricky Lee · Post by **Ricky Lee** » Sun Mar 30, 2008 9:37 am

Thanks, I should have known Sozo doesn't make a .47uf cap, his closest would be the .68uf. However, this one seems to be working but sounds terrible when connecting the master volume, fx loop and MV aren't getting along well together. I know once I get these two tuned in the system will sound great.

franc · Post by **franc** » Wed Apr 02, 2008 2:37 am

Another Q:

I want to be able to switch the loop on or off. Or I should actually say: disable the effects in the loop.

As I see it, I have two options:
1. Bypass all the effects by connecting the tips of Send and Return

2. Bypass the entire loop by switching the wiper of the Treble pot back to the 22n of the PI (and at the same time, disconnect that 22n from the buffer tube).

The second option would really bring the amp back to stock, but would it change the sound much? I want to be able to do this using a footswitch while playing, so I wouldn't want a big change in volume/sound or too much switching noise altogether.

Ideas?

novosibir · Post by **novosibir** » Wed Apr 02, 2008 7:16 am

Just switch the send signal after the .47 to ground. This doesn't pop and the effects device already won't be fed anymore - and the decay of the effects amount before switching won't be cut awful.

Larry

franc · Post by **franc** » Wed Apr 02, 2008 4:12 pm

Thanks alot Larry! I'll try that.

Guitar Adjuster · Post by **Guitar Adjuster** » Wed Apr 02, 2008 4:40 pm

Ok I am being lazy here as I don't want to go through all 351 post---can someone post a layout of this effects loop or e-mail it to me?

Guitar Adjuster · Post by **Guitar Adjuster** » Thu Apr 03, 2008 5:51 pm

Bump.....

novosibir · Post by **novosibir** » Thu Apr 03, 2008 8:44 pm

Guitar Adjuster wrote:Ok I am being lazy here as I don't want to go through all 351 post---can someone post a layout of this effects loop or e-mail it to me?

Guitar Adjuster wrote:Bump.....

GA, that's what I wrote in the first post of this topic:

novosibir wrote:Although I don't intend to post it openly at the Metroboard, so that not everyone of those thousands of 'not members' simply may download it...

... but I'll send it to each Metro member by request for personal use and also to professional amp modders or amp builders for commercial use, if they are registered members here at the Metro board.

Yes - it's for Metro board members only!

Simply drop me a PM with your email address and tell me, whether you like to get the loop schematic as a pdf file or as a bmp file - and already I'd kiss it good bye to you!

... and the reason, why nobody has posted it here or has sent it to you in an email yet.

But I'll send you the schem now as a pdf

Larry

Guitar Adjuster · Post by **Guitar Adjuster** » Thu Apr 03, 2008 11:01 pm

Got it, thanks Larry!!!

johniss0001 · Post by **johniss0001** » Mon Apr 07, 2008 4:48 pm

i know this might be late but i want to connect this effects loop to a sound city pa 50 head i know my PI is an ecc81 so that is easy to find and wire. my problem is i want to use a rack effects processor in the loop i am thinking bout a zoom 1201 or a zoom 1204. will this circuit have a high enough buffer for this unit i want to know before i go any further

novosibir · Post by **novosibir** » Mon Apr 07, 2008 7:43 pm

johniss0001 wrote:will this circuit have a high enough buffer for this unit...

It will!

Larry

johniss0001 · Post by **johniss0001** » Mon Apr 07, 2008 7:57 pm

can i get a copy of this effects loop if you don't mind i sent you a pm with my email addy earlier but here it is again

jaross AT HoTmAiL DoT CoM

Ricky Lee · Post by **Ricky Lee** » Mon Apr 07, 2008 8:21 pm

This FX loop does NOT affect or color the amps tone in anyway noticeable. I have listen to my amp both with and without the FX loop and there is no need to use a by-pass switch to take it out of the circuit. As far as I'm concerned installing an on off switch is just a waste of space and an unnecessary hole in the amp. This is one great loop. Thanks Larry!