Parallel effects loop for Marshall style amps

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novosibir
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Re: Parallel effects loop for Marshall style amps

Post by novosibir » Mon May 23, 2011 7:27 am

Seems that a massive inductive/capacitive coupling based oscillation within your loop circuit is killing/cancelling the signal.
Any huge bug in the lead dress? Keep in mind, that inside tube amp circuits due to its high sensitivity and stray fields everywhere you can't build as compact as possible, like i.e. inside cell phones.

Larry
The fault almost always is sitting in front of the amp :wink:

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Re: Parallel effects loop for Marshall style amps

Post by nasoftz » Mon May 23, 2011 10:36 am

novosibir wrote:Seems that a massive inductive/capacitive coupling based oscillation within your loop circuit is killing/cancelling the signal.
Any huge bug in the lead dress? Keep in mind, that inside tube amp circuits due to its high sensitivity and stray fields everywhere you can't build as compact as possible, like i.e. inside cell phones.

Larry
Maybe you 're right .. ... ...?? XD last time I installed it in my 2203 I did get no problems thanks to the big clear spaces avaible in stock marshall XD...
So I'm going to recheck as soon as possible.
I remember only that the grid and cathode from input part of the tube run really close together... maybe this is a huge lead dress problem?
Maybe better to use shielded wires to go in and out from the Master to the loop pcb?
I 'm able to find only RG58 (50ohm) coaxial antenna cable , will it make the job?
Thanks for the help Larry ^^

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Re: Parallel effects loop for Marshall style amps

Post by nasoftz » Thu May 26, 2011 3:10 am

update: checked lead dress, the shielded cable just improved the "send" signal a bit, Loop is fully working, but I still get kicks on my ass everytime lowering the send pot to "2"or "0"... Im going to remove the big electrolitic cap and wiring it alone from the loop pcb ... My suspect is that cap on B+ is too much close to the grid input signal...

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Re: Parallel effects loop for Marshall style amps

Post by nasoftz » Mon Jun 06, 2011 10:13 am

ok!! only to report that finally I got another working Larry parallel loop installed on my Peavey Classic 20! the goal was to replace all signal wires with shielded ones and find the right place to install the additional pcb! ^^
Amazing! ;)
Again,many thanks Larry!

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novosibir
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Re: Parallel effects loop for Marshall style amps

Post by novosibir » Mon Jun 06, 2011 11:07 am

Glad to hear, that you got it fixed :D

Btw.
nasoftz wrote:To Larry:
2 days ago surfing on the internet I found a copy of your schematic uploaded by "someone".. like I know, when I got it from you long time ago, you never gave the permission to make it public... Please contact me is you need to know that adress...
Thanks for the hint! This is very appreciated!

To all & everybody, who got a FX loop schem from me in the past:

The mentioned schem was hosted from a guy in Poland here:

http://s231.photobucket.com/albums/ee22 ... chematics/" onclick="window.open(this.href);return false;

... and it has cost me a lot of efforts and proof, until Photobucket has pulled my schem off of this page.
I've never sent a schem to this guy, so he got it from anyone else - despite I told everybody to not forward this schem to anyone else :twisted:

If anyone of you is stumbling over my FX loop schem anywhere in the web, so please let me know about immediately!

Larry
The fault almost always is sitting in front of the amp :wink:

Larry's Website now with included Pix's Gallery

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Re: Parallel effects loop for Marshall style amps

Post by paulster » Mon Jun 06, 2011 1:41 pm

novosibir wrote:To all & everybody, who got a FX loop schem from me in the past:

The mentioned schem was hosted from a guy in Poland here:
<snip>
... and it has cost me a lot of efforts and proof, until Photobucket has pulled my schem off of this page.
I've never sent a schem to this guy, so he got it from anyone else - despite I told everybody to not forward this schem to anyone else :twisted:
Larry has taken his time to design and draw up a tube effects loop and given it to members of the forum to use in their own amps.

This was a goodwill gesture to the Metroamp members, and still people can't respect the simplest part of the deal - keep it to yourself.

If someone you know wants the schem then it's hardly difficult to go through the proper procedure to get it. But just sending it onto them so they don't have to request it personally isn't part of that deal. So show some respect.

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Re: Parallel effects loop for Marshall style amps

Post by Roe » Mon Jun 06, 2011 4:24 pm

novosibir wrote:..

If anyone of you is stumbling over my FX loop schem anywhere in the web, so please let me know about immediately!

Larry

will do Larry
Last edited by Roe on Mon Jun 13, 2011 10:48 am, edited 1 time in total.
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Re: Parallel effects loop for Marshall style amps

Post by nasoftz » Mon Jun 13, 2011 10:18 am

Still Here!!! ^^ ... with a little present 4 You, Larry! ^^
...and
to everyone who wanna listen Larry's loop in action on 50.000 watt stage take a look below ^^
flanger, delay and whammy throught the loop (JCM800 2203 Loop installed after MV)
http://youtu.be/xr7kFRZEnvw
Again&again&again----------> Thank you so much!!

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Re: Parallel effects loop for Marshall style amps

Post by valvetones » Wed Sep 07, 2011 7:08 am

Looks as though Larry is the man!

I'm really interested in this idea, as I am a fan of Eddie Van Halen; however I dont want to copy his tone- I want one all of my own.

I used to plug my FX (crybaby, guvnor, tubescreamer, DD3, pitchshifter, modded ME6) into the low input of my JCM800 head. I then run this through 1 2x12 JCM800 cab and 1 4x12 1960A cab. I read an article that said 'whats the point of a great valve amp if youre not gonna use great valve distortion?' This struck a chord with me. (ha ha)

So now I use the high input of the JCM800 head, and get sweet tone. The thing is, all the FX are really OTT. I have adjusted things as much as possible, reverb and delays sound ok, tubescreamer used as a solo boost (done away with the guvnor) but the crybaby is way loud, plus the FX hiss a bit. I have a bypass that takes all FX out the signal chain, and it sounds great- but I want to add a few FX!

I dont really want to screw my 800 head up too much, and this loop sound like the thing, but I dont have 10 posts. I have a DI line level out, effectively if I use this to ive the FX, could I use a 2nd amp? I think the loop may be the way forward. Larry sounds like a genius!

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Re: Parallel effects loop for Marshall style amps

Post by veptele » Fri Sep 16, 2011 6:26 pm

I have a couple of questions regarding the install, please forgive me if it’s been answered in the 41 pages of this thread.

I have a 1970 Superbass that I brought back from the dead. I completely rebuilt it from the ground up and recently added the Lar/Mar master volume. The amp sounds great and I couldn't be happier. Now I'd like to take it to the next level and install this loop. The issue I'm having is that it's not clear on where to tap the signal. I can't interpret schematics so that really doesn't help me too much. I'm relying solely on the instructions that came with the kit. Has anyone installed this loop with the Lar/Mar master volume? Could someone possibly walk me through how to tap the signal. I'm good with the remainder of the mod.

One other general question, upon completion is it safe to run with two power tubes pulled?

Any insight would be greatly appreciated.
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Re: Parallel effects loop for Marshall style amps

Post by jerrydyer » Thu Apr 12, 2012 3:03 pm

you tap in at the PI (phase invertor node) there is an 82k res and a 100k res that join together that is your node. you can tap there or follow it back to the cap and tap there.
vids.
http://www.youtube.com/user/jerrydyer?feature=mhw4" onclick="window.open(this.href);return false;
http://www.dui-specialist.com" onclick="window.open(this.href);return false;

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Re: Parallel effects loop for Marshall style amps

Post by sfb » Sun Feb 10, 2013 5:25 am

Where can I get the schematic for this?

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Re: Parallel effects loop for Marshall style amps

Post by malig » Fri Feb 22, 2013 7:08 am

Can I get this schematics I asked Larry 2 times (very politely but he does not respond, even if the PM are read)

So please can someone give it to me ?

Thank you

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Re: Parallel effects loop for Marshall style amps

Post by negroj9 » Thu Feb 28, 2013 11:52 am

Ok, I really would like to try this loop in my modded jcm800 but I haven't posted enough, yet.
Does it use opamps or what? Gonna make an order soon, just want to know before :thumbsup:

Cheers

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Re: Parallel effects loop for Marshall style amps

Post by Froumy » Sat Mar 23, 2013 9:51 pm

Larry sent me this years ago, but I didn't have the need 'til recently. Put it in today. This loop deserves a BUMP, and another thank you! Thanks again, Larry!


As a side note. If you're limited for space, and trying to build this quickly on a small drop in board.... Resist the urge to try and squeeze in your filter cap too close to the V3A cathode components....Unless hum and occasional squeal is the FX your going for. Not that I'd do such a silly thing... Doh!

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