Happy Effects Loop Surprise!

[The Ballzz]

Well Fine Folks,
I've been bustin' everybody's chops and beggin' for awhile for help and advice with effects loops in amps not designed for them. Well I just installed a passive loop (just two jacks, one of them a switching jack) into my bone stock 5E3 Tweed Deluxe and it works very well, for my purposes! Delay/reverb before the input of the amp sounds (IMHO) like doo-doo!

It's inserted it at the blue arrow:

Deluxe-5E3-schematic loop copy.jpg

FWIW, I'm an echo/delay junkie and like it best when gently "softened" with a little bit of reverb. On the plus side, I don't use stomp/pedal/foot/thingies for this purpose, but instead semi professional, sound system style, rack mount units, currently a Lexicon MX300, which can provide up to a five second "tap tempo" synchronized delay and reverb at the same time. It also provides the more professional options of being able to choose either +4db or -10db operation for the output and at least a level control on the input. I am amazed and so pleased at being able to have nicely operating reverb and delay added to my Tweed Deluxe!

While I would love to have a nicely buffered loop such as the ones offered by Metropoulos and Granger, but don't want to suck down the limited B+ in the 5E3 and there is simply not enough real estate to install one in the chassis. I figured if the passive loop didn't work well, at least it could provide the access point to utilize some sort of external loop that I could find/design/build. This no longer seems necessary. It has however inspired me to decide to put at least a passive loop into everything I build and at least drill the holes with the spacing to accommodate the Granger Loop that I have used and liked on other amps. Kurt Granger designed in a cool feature that has level control pots on both input and output and they get accessed with a small screwdriver, through the jacks. very well thought out and surprisingly transparent!

https://grangeramp.com/ufxloop.php

I would however appreciate any advice and/or comments concerning any long term pitfalls in my current configuration/usage!

Thanks Fine Folks,
Gene

[frankdrebin]

well,different people,different tastes.
generally speaking an effects loop is needed whenever the preamp distorts so much that ruins the effected signal,such as reverb or delay.
In amps like this or the 18w Marshall i would just derive the fx send from input 2 of the channel feeded by the guitar,and fx return to input 1 of the other channel.

[The Ballzz]

@frankdrebin
The method mentioned can work quite well, when/if most distortion, coloration, overdrive etc. is accomplished with devices between the guitar and the amp's input. On the other hand, when all that coloration and/or distortion is achieved through the amp, the feed to the input of the delay needs to be derived a bit later in the signal path! This makes it so that the recorded "repeat" that gets played back sounds most like the un-delayed note coming out of the speaker. An example of some of the kind of stuff I'm shooting for was mastered by late guitarist Jim Wilsey and well demonstrated on Chris Isaak's Wicked Game:

https://www.youtube.com/watch?v=dlJew-Dw87I

Mr Wilsey went on to make most of his playing career center around that sound/technique and I'm simply endeavoring to refine the tone and operation a little bit! Obviously, the best way to achieve what I want would be to have a great sound guy on retainer, who knows all my echo cues and could pump it back through the monitors for me to work with, but that ain't happenin' at the corner Gin Mill! I used to do a two amp, wet/dry rig that sounded amazing, but was simply too much of a P.I.T.A. to deal with, on a daily basis!

Thank For Your Thoughts,
Gene

[pdf64]

If a simple, non ideal solution works fine in a particular scenario, then that's great, there's no point using a more complex arrangement.
But it should be noted that a proper fx loop should have a fairly low impedance output; the send impedance of the arrangements mentioned so far are very high, >100k, which will make their upper bandwidtth very dependant on the parasitic capacitance of the cable they're feeding.
Also its max signal level should limited to that appropriate for the fx used, ie somewhere between instrument and pro line level.

...when all that coloration and/or distortion is achieved through the amp, the feed to the input of the delay needs to be derived a bit later in the signal path...

Other than the tone control, on the face of it, from the arrangement described, there seems little opportunity for any amp coloration/distortion? As the input stage would normally operate within its linear range.

...This makes it so that the recorded "repeat" that gets played back sounds most like the un-delayed note coming out of the speaker...

But following that rationale, it seems to be best to process the 'repeat' exactly the same as the dry signal, ie feed it into the amp's regular input?
Rather the usual benefit of a proper fx loop is that the signal that the fx unit's output doesn't then get (excessively) coloured/distorted up by the amp, ie so that the reverb and echoes have the best chance of sounding like a natural ambient response.

For scenarios where power amp overdrive is significant, rather than trying to hammer a square peg into a round hole with an internal fx loop, my preference is just to mic the amp's speaker, feed that into the fx, and send a 'wet only' signal the PA / monitors, or into a very small keyboard type combo.

[DimenBrun]

If that passive loop works for you then great. I don't think you would be distorting that first gain stage much at all so I don't see much benefit, but I haven't tried it. All the loops I've done have been on MV amps, between pre and power amp.