I've read posts on TAG where people are discouraged to use an EFX loop in an Express build based on possible sonic results. OK, but has anyone actually tried it?
Since the one from George at Metroamps was created for a typical Marshall Plexi circuit - and the reviews are good - I am pretty convinced it will work well in a Rocket. However the Express is my real question.
In one example that I have seen, made by Granger, there are adjustable inputs and outputs via trim pots plus a TB switch, all good stuff. Are we all sheep here or has someone tried this in an Express?
Most people stall out when fixing a mistake that they've made. Why?
rooster wrote:I've read posts on TAG where people are discouraged to use an EFX loop in an Express build based on possible sonic results. OK, but has anyone actually tried it?
Since the one from George at Metroamps was created for a typical Marshall Plexi circuit - and the reviews are good - I am pretty convinced it will work well in a Rocket. However the Express is my real question.
In one example that I have seen, made by Granger, there are adjustable inputs and outputs via trim pots plus a TB switch, all good stuff. Are we all sheep here or has someone tried this in an Express?
I've been wondering this for a long time too! In thinking of trying the metro loop in my "RJ PCB Express"...
The 3rd stage clips at higher settings so you need the “send” after it. The signal is very strong there so you must bring it way down before the send. Then you need to bring it back up after the return and before the PI to preserve what the PI is expecting at least somewhat. I used a parallel approach via a voltage divider/splitter to create the tapped attenuated send signal while also sending the dry path around the loop for blending back with the return boosting stage. I have to flip the phase with a small transformer since the 2 would be out of phase from the return boost stage. My voltages are lower than Express so the divider values would vary. 18k on the send is where I ended up. A send control could be used there instead.
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Jjman, read this, from the notes on the Granger unit:
"the FX loop will reduce your Send signal 10db after the buffer stage of the circuit. On return, the signal is input into a gain stage that adds 16bd of gain. Therefore, the FX loop will deliver a net signal that is 6 db higher. This can be trimmed by using the Send and Return internal trim pots..."
If you read this like I do, it seems this Granger FX Loop is capable of inserting itself into an Express quite nicely, and with the added efx. How do you read this? I do like the idea of parallel efx, too, but it also seems a much easier proposition inserting this Granger unit into the Express in a parallel loop than doing what you did. I do admire your effort there, however!
Most people stall out when fixing a mistake that they've made. Why?
I owned an Express clone with an FX Loop -- it was a Two Rock Ruby.
It had a switch where you could cut the FX Loop and Master Volume out of the circuit.
I don't remember the details, but I tried both of them (the FX Loop and the MV). The amp sounded SOOO much better with them out of the circuit. The difference was so dramatic, I never used them again.
I realize there are different FX loops. But that amp made me a believer that you don't want mess too much with the original Express design.
If you want to have a usable FX Loop with an Express (and a post-everything MV, and a line out), you might want to check out the BadCat Unleash... It sits after the amp and before your cab, and does what you need it to do.
Mark thanks for the schematic. Man, I can understand why you might want to avoid the EFX loop in the TR. That looks very home brew, with too many fine tuning stabs to it. Hm.
Thank you all for the input. At this point I've decided to install the Granger unit. I ordered it a week ago and it arrived four days later. Seems built well and was $77. Since I have two Express right now, one with the LarMar MV, I'm up for the experiment. I'll put it in the MV version. I'll post some results. I will also consider the parallel loop idea, something that seems a better conclusion to the Express circuit actually but we'll see.
The reason any of this came up is because a friend brought a bogner shiva to the house and he plugged a TC HOF verb into it and it sounded really great. Better, than it does when placed in front of my Express. Eh, I need to try it.
Most people stall out when fixing a mistake that they've made. Why?
I will offer one to consider. I have NOT tried this in a Wreck, so this is a DRAFT idea for a Wreck.
However, I do use this in my Dumblish inspired amps. I use a paralleled FX with a 12AY7. It works great for me & the active FX makes a fantastic master volume for my purposes.
I use it with digital delay, analog delay and digital reverb with good results.
I strongly dislike delay or reverb pedals between the guitar and amp input. Waaayyy too noisey for me.
From what I've read about the Trainwrecks, I can see that a series FX might not be a good choice. However, I would this paralleled FX with a low gain tube like a 12AY7 or 12AV7 could be a reasonable consideration.
Note there is a DPDT mini-toggle to switch it in or out.
with respect, 10thtx
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10thTx, hey, thank for the schematic. One thing I have to point out? Since the cathode follower does not change the phase of the signal, the loop you show will reverse it as it leaves the 2nd half of the 12AY7. This would be a problem in my world.
Also, looking at the DPDT switch and it's connection points, I don't see where the original signal is joining the efx loop in parallel.
Most people stall out when fixing a mistake that they've made. Why?
Also, looking at the DPDT switch and it's connection points, I don't see where the original signal is joining the efx loop in parallel. Question
That is because the "original" signal is not completely paralleled. However, the "wet" and the "dry" mix are paralleled. It certainly sounds different then the series FX and more of the "original" signal is retained using this method.
Since the cathode follower does not change the phase of the signal, the loop you show will reverse it as it leaves the 2nd half of the 12AY7. This would be a problem in my world.
Can you please explain this some more? And if this wouldn't work on a Wreck, could you show a schematic of an effects loop that would resolve this problem?
It may be something specific to the amps I've tried it in but it has always worked for me regarding of the number of amp gain stages when I have installed it between a preamp and LTPI. I've used it with 2, 3 and 4 gain stages in a preamp .......... then into the FX ......... then into the LTPI.
rooster wrote:Jjman, read this, from the notes on the Granger unit:
"the FX loop will reduce your Send signal 10db after the buffer stage of the circuit. On return, the signal is input into a gain stage that adds 16bd of gain. Therefore, the FX loop will deliver a net signal that is 6 db higher. This can be trimmed by using the Send and Return internal trim pots..."
If you read this like I do, it seems this Granger FX Loop is capable of inserting itself into an Express quite nicely, and with the added efx. How do you read this? I do like the idea of parallel efx, too, but it also seems a much easier proposition inserting this Granger unit into the Express in a parallel loop than doing what you did. I do admire your effort there, however!
I don't know how much a 10db reduction would be but I suspect it may not be enough to bring it down enough to avoid overdriving floor-type pedals. The internal trimmer would probably help there. I calibrated the send strength on mine to be just a hair below the point that triggers the clipping light on a reverb unit I have. I used my guitar with the volume control maxed for a real world calibration. It's a 99% reduction in voltage based on the math of 2.2megs/2.218megs on my voltage-dividing send tap. A shot I took of my scope shows the 3rd stage clipping at 70Vp-p with a likely 500MVp-p on the input at max volume control. So I guess my send can send about 700MVp-p which sounds in the ballpark. Overdriving effects can be ok but is often going to create distortion you don't want. Many “professional” effects have trimmers on their inputs and can take stronger levels but I wanted the option to be able to also use floor pedals with no fear of overdriving them.
10thTx, those two schematics are fine, proper phase. Your first drawing shows an out of phase signal arriving at the PI.
A cathode follower path does not reverse the phase of the signal exiting the stage.
All this said, since you do not really show a parallel efx loop it will sound fine. However, if you did have the original signal combined with the reverse polarity efx signal there would be phase cancelation - a noted lack of bass in the finished signal. Shitzbah.
Most people stall out when fixing a mistake that they've made. Why?
Mark, just looked at your schematic. That looks like a plausible parallel solution to the problem. I can install the Granger loop here and it would be phase correct, as well. It also might be interesting to hear the delay not as distorted as it would be when it leaves the 3rd stage, too. Hm, thanks for posting this. Oh, I do notice the bypass option here will be a negative and I will have to disengage the jack controlled automatic bypass when nothing is plugged into the loop but this is do-able.
Have you actually used this idea or heard it in play?
Most people stall out when fixing a mistake that they've made. Why?
