FX loop

[jdh]

A true differential amp needs a current source. As a mixer 1 input is inverted, so the output = A-(-B) = A+B. The circuit gets complex when you consider all of the extra components, and this is probably why we don't see a lot of them. The attached is a first stab at a battery powered version. It was a bit compressed/mushy, yet it did work and there were no solid state components in the signal path. The ac powered version requires 4 extra xfmr windings (EZ81 negative rectifier) plus a biased heater voltage for the pentode. It almost doubles the parts count for a basic D-Style amp.

[Structo]

I don't know where bluesfendermanblues gets his information.
From what I have read, a serial loop is good for time based effects.
My reverb and delay sound great through mine.

[greiswig]

I don't know where bluesfendermanblues gets his information.
From what I have read, a serial loop is good for time based effects.
My reverb and delay sound great through mine.

He's not the only one who thinks parallel is better. You must be mixing wet/dry at your effects unit, Tom, otherwise you'd be hearing ONLY the delay, or ONLY the reverb in a serial setup. And as I said before, if you are mixing in your effects unit , you're "processing" even the dry signal to some extent.

[bluesfendermanblues]

yep, as simple as that

If you use top qual gear with very high converter and processer bitrates, you will be less senstive to a serial loop.............but spend a lot of cash, time and effort on a fine Dumble like amplifier, only to ruin its sound with a poor processor in a serial loop, kind of silly, huh? Only my opinion some might even prefer an ol' 8-bit roland, but not me

[dogears]

Or get a rack like mine and get both the tone and no digital in your dry path... Sounds much better than a parallel loop. Not even close. The Switchblade can change from series to parallel based on patch. Best of both worlds! They are a grand though
http://soundsculpture.com/products/switchblade.htm

yep, as simple as that

If you use top qual gear with very high converter and processer bitrates, you will be less senstive to a serial loop.............but spend a lot of cash, time and effort on a fine Dumble like amplifier, only to ruin its sound with a poor processor in a serial loop, kind of silly, huh? Only my opinion some might even prefer an ol' 8-bit roland, but not me

[greiswig]

I'd never even heard of that Switchblade, Scott. That's pretty cool. I'm not sure it has enough in/outs, though.

[Tonegeek]

Parallel loops always facinated me but I have yet to try one that works for me. I have no complaints at all about my built in serial Dumbleator. I agree with the folks that say it enhances the sound just being in the circuit so I did not even put a bypass switch on the last amp I built. I use digital effects and suffer no noticeable degredation of the signal on the dry side. I did "tune" my loop slightly to compensate for high end losses in my setup though, mostly caused by the cables.

[Guitarman18]

dogears wrote:

the TC2290 that Robben bases his tones on is an all analog signal path that internally mixes the signal in parallel.

Having just completed my D'lator clone, it has made me realise that the quality of my rack units are desperately in need of upgrading. Does anyone know if units such as the TC G-force have adopted this 'analog signal path' topology? Alternatively, apart from the switching capability of the Switchblade, could any high quality line mixer be used to mix in effects, whilst keeping an anolog signal path also?

[dogears]

I believe just the 2290 and the older Intellifex units maintain the dry signal in the analog world.

You could use the Switchblade to mix a G Major in 100%. Your dry tone would stay analog.

dogears wrote:

the TC2290 that Robben bases his tones on is an all analog signal path that internally mixes the signal in parallel.

Having just completed my D'lator clone, it has made me realise that the quality of my rack units are desperately in need of upgrading. Does anyone know if units such as the TC G-force have adopted this 'analog signal path' topology? Alternatively, apart from the switching capability of the Switchblade, could any high quality line mixer be used to mix in effects, whilst keeping an anolog signal path also?

[Fischerman]

At least part of the D'lator's mojo seems to come from cable capacitance tapering off highs...which should be simulatable with capacitors. Other than that, I don't know what the D'lator does to signal: does it goose the return signal considerably so it hits the PI harder? Is there distortion or harmonic addition taking place inside the D'lator tube?

I'm not sure it's purely cable capacitance. Any loop will have that although with a parallel loop it wouldn't affect the dry tone. The D'lator itself affects the tone a little bit. The D'Lator doesn't 'goose the signal to the PI' per se...because the signal going into the PI is adjustable via the Return Level control. IMO (and this is truly a guess/opinion) is that the Send stage in the D'Lator affects the tone a little and...depending on who you ask...in a good way. You could crank the Masters and slam the Send stage but then dial the Send Level way back so the effects didn't get slammed and dial the Return Level down so PI didn't get slammed...or any number of combinations. The stock D'Lator Send stage doesn't seem to have an abundance of headroom.

Bottom line is we are building a tone from the ground up. Thinking in terms of 'ruining this fine Dumble tone with a serial effects loop' is totally missing the point. We're not trying to get the acoustic tone of our electric guitar out of the speakers...we are shaping and manipulating the tone all along the way. Who says it can't sound better? Whether it's Jimi with a Fuzz Face, Robin with a Uni-Vibe, Clapton or Iommi with a Rangemaster, SRV with a Tubescreamer, Blackmore with a reel-to-reel preamp, Johnson with a Tube Driver (mostly solid state) or whatever...they all put solid state devices before their fine all-tube amps and set the standards for great tone. Solid state!?!? oh the humanity!

EDIT: When Eric Johnson had the SSS in his rig he usually had a Tubescreamer in a rack somewhere that was ALWAYS ON. And of course he had a delay for that amp too...anytime you hear an infinite delay (like the ACL DVD intro to Cliffs of Dover or the end of Are You Experienced is the delay going to the SSS...watch him tweak the SSS volume down at the end of AYE).

I built the D'Lator into my amp and the difference is subtle but I prefer it with the loop in the path at all times...whether I'm using it or not. It just seems to sweeten/fatten/soften the tone a tiny bit. And it's not my only amp where that is the case.

[glasman]

I believe just the 2290 and the older Intellifex units maintain the dry signal in the analog world.

The Rocktron Xpression also has the analog bypass (when not using the HUSH circuit) but based on reviews it is something to stay away from ......

[Guitarman18]

Sorry to revisit an old topic but I'm looking to get a new FX unit and am wondering if anyone has any experience using the TC Electronic G-Major in their D'lator setup, if so, what was the verdict? At present I have an Alesis Midiverb 4 that sounds way less than spectacular (Craptastic. )
I see that dogears lists it on his web site in the gear page, but I wonder if that is current gear, in light of the pictures posted on the previous page.

[drz400]

Hi Greiswig,

as you know, Dumble (as far as I know) never offered a "parallel" Dumblelator. Do you think, he did so, because the "parallel just sounds better" effect only appears, when you use clones of Dumble amps together with clones of Dumblelators and not when you use his original devices, or do you think, Alexander Dumble just did not know how to do a parallel Dumblelator?

Best regards

Max

Max, nope...if anyone was capable of designing a parallel loop, it was HAD. He had his reasons, I'm sure. But there are a lot of FX types that I wouldn't want to run serial.

This is a great discussion! Scott and others who have tried the real-deal Dumbleators prefer them. I haven't ever tried one (anybody in PDX wanna let me hear one?), so I don't know what it does to the signal. O'Connor's goal with his FX loop was transparency, as far as I know. At least part of the D'lator's mojo seems to come from cable capacitance tapering off highs...which should be simulatable with capacitors. Other than that, I don't know what the D'lator does to signal: does it goose the return signal considerably so it hits the PI harder? Is there distortion or harmonic addition taking place inside the D'lator tube?

One other thing I like about O'Connor's loop: you can build it into the amp, as it does not require additional transformers, a rack, etc. I've heard here that people who tried to do that with a D'lator were not as happy with it, but once again I have no idea why.

But for the OP, I think it's fair to say that a serial loop will require you to figure out how to do mixing externally from the amp, and you may not dig what the coloration does to the whole signal unless it's a really top-notch FX unit.

Tubes even when used as a plate follower ala Tut do not make as good of a mixer as an opamp mixer. You also loose too much gain when using a tube as a plate follower. The coloration of a simple opamp based mix circuit is nada especially when you compare it to going through converters or analog in the effects. My vote is tube series loop, if you need a mix then buy or make one with opamps. It is really pretty simple

[Guitarman18]

Guitarman18 wrote:

Sorry to revisit an old topic but I'm looking to get a new FX unit and am wondering if anyone has any experience using the TC Electronic G-Major in their D'lator setup, if so, what was the verdict? At present I have an Alesis Midiverb 4 that sounds way less than spectacular (Craptastic. )
I see that dogears lists it on his web site in the gear page, but I wonder if that is current gear, in light of the pictures posted on the previous page.

I've got an option to buy one, so would greatly appreciate any comments ASAP.

Many thanks,

Paul.