Parallel effects loop for Marshall style amps

jerrydyer · Post by **jerrydyer** » Wed Feb 21, 2007 12:06 pm

he kept referring to me when answering questions about a boost. I dont care really about the boost. I thought that was you. sorry.

joshwilson3 · Post by **joshwilson3** » Wed Feb 21, 2007 2:50 pm

jerrydyer · Post by **jerrydyer** » Wed Feb 21, 2007 3:02 pm

Larrys would be perfect for that. You could use the return as the recovery buffer just like a master I beleive.

novosibir · Post by **novosibir** » Wed Feb 21, 2007 3:22 pm

joshwilson3 wrote:If I wanted to, could I run a seperate preamp into the return of this loop, and the master volume would work just like if I plugged up to the front of the amp?

You can place the loop right after the treble pot in your amp and place the master after the loop in front of the PI, then (as a post loop master) it would work fine.

joshwilson3 wrote:Would the Marshall preamp be bypassed?

The preamp in the Marshall furthermore would work - running parallel to your external preamp signal and mixed together in front of the loop's recovery stage.

joshwilson3 wrote:I know this is a parallel loop, so I don't know what difference that would make compared to a series loop.

The difference i.e. is, that with a serial loop and a preamp plugged into the Return, the preamp of the Marshall can't be used.

joshwilson3 wrote:What I'm wanting to be able to do is to run the preamp of say a mesa boogie into the poweramp of my Marshall, and still be able to use the master volume of my marshall. Also, when I do this, I would need the preamp in the Marshall bypassed. Think of it like switching in a different preamp.

That requires a parallel effects loop.

joshwilson3 wrote:I would also like to have an effects loop for when I'm playing through the front of the amp.

As long as no external preamp additional is plugged in, it's an effects loop.

joshwilson3 wrote:For this application, what do you think would work better, a parallel loop or series loop?

By all means a parallel loop!

Larry

thinlizzy · Post by **thinlizzy** » Wed Feb 21, 2007 3:26 pm

jerrydyer wrote:he kept referring to me when answering questions about a boost. I dont care really about the boost. I thought that was you. sorry.

No problem at all!!! and I do care about the Boost

jerrydyer · Post by **jerrydyer** » Wed Feb 21, 2007 4:20 pm

novosibir · Post by **novosibir** » Wed Feb 21, 2007 6:12 pm

jerrydyer wrote:Larrys would be perfect for that. You could use the return as the recovery buffer just like a master I beleive.

Right!

You also can leave the Master at the tone stack and after the Master into the loop section. Then you have the Master only for the Marshall's preamp section - and the Return Level only as a Master for the external preamp.

Larry

joshwilson3 · Post by **joshwilson3** » Fri Feb 23, 2007 3:19 am

novosibir · Post by **novosibir** » Fri Feb 23, 2007 3:25 am

joshwilson3 wrote:If I was running the preamp of a Mesa Boogie MKIV into the return of the loop, I wouldn't want the Marshall preamp mixed in with that. I would want the Mesa preamp ran to the poweramp bypassing the Marshall preamp.

So, is my assumption correct? If so, is there something that could be adjusted to meet what I need and keep a really cool effects loop? Or would I need to go serial?

Take a simple SPST switch and switch the conjunction between the 820K and the 180K to ground - and already you have made it to a serial loop and your internal Marshall preamp section is dead quite

Larry

joshwilson3 · Post by **joshwilson3** » Fri Feb 23, 2007 4:01 am

novosibir · Post by **novosibir** » Fri Feb 23, 2007 4:36 am

joshwilson3 wrote:If I did that, it wouldn't make it sound like crap, would it? I remember you talking earlier about turning this into a serial loop and the preamp being ran through semiconducters, etc.

Nothing is running through semiconductors, when you only plug a (tube-) preamp into the Return - w/o an effects device between preamp and Return jack.

joshwilson3 wrote:And would the SPST switch you are talking about work better for me than using a DPDT switch and bypass the resistor after the Return Level's wiper with an additional 220p with one half of the switch, while the other half is breaking the line of the 820K?

You can switch the 820K/180K conjunction to ground as well as break the line of the 820K - but an additional 220p you don't need to recover lost highs, because there's no large resistance in front of the Return Level.

joshwilson3 wrote:So far, it looks like I would need a switch for series/parallel, switch for on/off, send volume, send jack, return volume, and return jack.

Yep! Then you'd have the hyper-astro-multi-tutti-loop

Larry

joshwilson3 · Post by **joshwilson3** » Sat Feb 24, 2007 4:30 am

novosibir · Post by **novosibir** » Sat Feb 24, 2007 8:00 am

joshwilson3 wrote:Ok, I got it. Though, I forgot to ask. When I would be running a preamp straight into the return of the loop, would the master volume on the front of the amp work like normal, or would the master be the volume on the return level?

Keep the amp's Master on the tone stack, then it further works as the Master for the Marshall preamp and the Return Level is the Master for your external preamp!

joshwilson3 wrote:I was thinking, would I even need a switch on the 820K/180K conjunction? If I plug a preamp straight into the return, there wouldn't be anything plugged to the front of the amp. So, would the Marshall preamp even be in the signal?

Simply set the Gain (Preamp Volume) to zero, to avoid the hiss of the Marshall's preamp in the mix.

Larry

joshwilson3 · Post by **joshwilson3** » Sat Feb 24, 2007 6:52 pm

Shaker · Post by **Shaker** » Sun Feb 25, 2007 2:56 pm

Larry,

A big thank you for this loop. I built it on a 2203 amp and it works really, really well !
Oh, and the master volume is a ppimv on it.