Parallel effects loop for Marshall style amps

joshwilson3 · Post by **joshwilson3** » Wed May 23, 2007 2:22 am

jngreene79 wrote:Yep, you can run an external preamp into the effects loop return. You can A/B them with a switcher. When using the return, the volume is a lower and (on a master vol) the Master has no effect on the return volume. I think Larry has addressed this and ways to remedy it. I'm trying to build a Dumble style clean channel into a small box and us that for cleans. Very cool loop, Larry

So, when you are running an external preamp into the return in a master amp, the master volume doesn't work?

Would the return volume act as the poweramp master volume?

jngreene79 · Post by **jngreene79** » Wed May 23, 2007 6:51 am

The return volume acts as a Master for the second preamp. It works perfectly and keeps the Marshall sound intact. The volume, even with the Return level dimed will be lower because you are only amplifying the signal with the recovery stage of the FX loop. Add a preamp and you can boost the volume to that of the Marshall. It's brilliant -2 amps in one.
My friend in the band Daylight Dies does this with a 5150. Though the effects loop is solid state, he uses a boss multi effects pedal in this same way for everything other than his distortion channel. It enables him to do everything live that was done in the studio (with a little bit of dancing on the pedal, of course). It's seamless.

joshwilson3 · Post by **joshwilson3** » Wed May 23, 2007 1:50 pm

jngreene79 wrote:The return volume acts as a Master for the second preamp. It works perfectly and keeps the Marshall sound intact. The volume, even with the Return level dimed will be lower because you are only amplifying the signal with the recovery stage of the FX loop. Add a preamp and you can boost the volume to that of the Marshall. It's brilliant -2 amps in one.
My friend in the band Daylight Dies does this with a 5150. Though the effects loop is solid state, he uses a boss multi effects pedal in this same way for everything other than his distortion channel. It enables him to do everything live that was done in the studio (with a little bit of dancing on the pedal, of course). It's seamless.

Sounds good. Do you get any noise by running an external preamp? I remember Larry mentioning about turning the preamp on the amp to zero when using an external preamp to keep the Marshall preamp from making noise.

jngreene79 · Post by **jngreene79** » Wed May 23, 2007 4:56 pm

I've got 4 gain stages in the amp I installed it in and it's fine, just ground the signal going to you 'host' preamp via A/B switch. I made one with a 3PDT push button switch. You could use a dtdt one. It won't be any noisier than normal.

Germanium_Boy · Post by **Germanium_Boy** » Wed May 23, 2007 10:20 pm

In first place, thanks to Larry and to Thinlizzy for his help!

I have a little doubt... I can't get capacitors with the correct values in voltage... Only biggers... For example, for the 470n of 100V I can only get a 470n of 450V

I don't know if it's very important this difference,... can you help me?

novosibir · Post by **novosibir** » Thu May 24, 2007 5:51 am

No problem to use a higher voltage rating!

The problem almost always is the space, because they are so big.

Larry

MRX2099 · Post by **MRX2099** » Fri May 25, 2007 10:48 am

Ok I have installed the "Larry/Rockstah" MV mod and love it, now can I install this FX loop with the master mod still intact, I don't want to drill any more holes could I use maybe 2 of the front inputs and route it that way?

Also Larry can I get the layout/diagram for this FX loop, I am goint to P.M. you so you''ll know to just sent it that way if you want, however is best for you..............

Thanks
Jeff

Germanium_Boy · Post by **Germanium_Boy** » Wed May 30, 2007 7:19 pm

I'm starting with the building of the FX Loop, and I have a little problem... By the way, thinlizzy is being very kind helping me, but I don't want to exceed his patience!

I explain my problem... because I haven't a lot of electronic skills (I'm a rookie, man

) I don't know where I have to connect exactly the B+ of the FX Loop... My amp is a JCM 800 50w 4010. Thinlizzy told me that I have to connect it to the point where R18(82k) and R21(100k) (look HERE)comes together, but I don't know if...

1) I have to solder the B+ wire BEFORE those resistors
2) I have to solder to the pin1 or 6 of the V3 (PI) where those resistors are soldered...

If someone can explain it, I'll be very grateful

And thanks to Rockstah for encouraging me to post here... Yes, my english isn't very perfect, I'm always a bit ashemed of writing here for this reason

novosibir · Post by **novosibir** » Wed May 30, 2007 7:40 pm

Germanium_Boy wrote:I don't know where I have to connect exactly the B+ of the FX Loop... My amp is a JCM 800 50w 4010. Thinlizzy told me that I have to connect it to the point where R18(82k) and R21(100k) (look HERE)comes together, but I don't know if...

You have to connect the B+ on top of the both resistors, there where they are connected together - or right after the 10K resistor of the power supply rail on top of the schematic (the side, where the arrow is facing to the 'x')

For all the others, who also aren't too much skilled in electronics:

Please don't flood my mailbox with your individual quests, awaiting an individual reply to each! Please post ALL your quests concerning the loop here in this topic - and here I'll reply to ALL of your quests!

Every quest might be of common interest! And there maybe still are 5 or 6 other members with the same or a similar quest, whom all is helped with one of my reply HERE at the same time

Thanks for your understanding!

Larry

Germanium_Boy · Post by **Germanium_Boy** » Wed May 30, 2007 8:01 pm

novosibir wrote:
Germanium_Boy wrote:I don't know where I have to connect exactly the B+ of the FX Loop... My amp is a JCM 800 50w 4010. Thinlizzy told me that I have to connect it to the point where R18(82k) and R21(100k) (look HERE)comes together, but I don't know if...
You have to connect the B+ on top of the both resistors, there where they are connected together - or right after the 10K resistor of the power supply rail on top of the schematic (the side, where the arrow is facing to the 'x')

For all the others, who also aren't too much skilled in electronics:

Please don't flood my mailbox with your individual quests, awaiting an individual reply to each! Please post ALL your quests concerning the loop here in this topic - and here I'll reply to ALL of your quests!

Every quest might be of common interest! And there maybe still are 5 or 6 other members with the same or a similar quest, whom all is helped with one of my reply HERE at the same time

Thanks for your understanding!

Larry

Thanks, man! You have explain it perfectly... Now It's time to get to work

thinlizzy · Post by **thinlizzy** » Thu May 31, 2007 4:57 am

Hi,

I'll try to open up the 2204 this weekend and make some photo's of the connection points in the amp. I'm just to buissy this week.
I'll mail you, Germanium_boy, sorry for the delay....

Marcel

jerrydyer · Post by **jerrydyer** » Thu May 31, 2007 12:47 pm

this amp has larrys loop go check it out give me your opinions. Let me know if its Amp Show worthy

http://mysite.verizon.net/ressquyj

Germanium_Boy · Post by **Germanium_Boy** » Thu May 31, 2007 5:03 pm

thinlizzy wrote:Hi,

I'll try to open up the 2204 this weekend and make some photo's of the connection points in the amp. I'm just to buissy this week.
I'll mail you, Germanium_boy, sorry for the delay....

Marcel

As I say, thanks again, man!

There's no hurry!

thinlizzy · Post by **thinlizzy** » Thu May 31, 2007 5:35 pm

Looks like a very hot amp, jerrydyer.

Exellent work!

Now how does it sound?

7string · Post by **7string** » Tue Jun 05, 2007 3:10 am

I'm making room on the board for this loop on my next build. A '75 100w metal panel. The layout i did looks cool. It has that longboard look like Larry gets on those crazy builds of his, as well as keeping the plexi look intact.

Has anyone ever put the send/return pots in the 2nd set of input jack holes? Or is that bad wire routing?

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.

Jerry's amp is purdy.