Designing a Brand New Effects Loop! Let me Know your Wishlist!

  • Thread starter Thread starter glpg80
  • Start date Start date
Jack Luminous said:
The perfect loop already exists, it is this device :

P1010005.png

%E5%90%8D%E7%A7%B0%E6%9C%AA%E8%A8%AD%E5%AE%9A.png


It is a parallel loop with kill dry, bypass function and send/return levels. It can handle pedal levels as well as rack gear. Put this in an amp and it will be perfect.
Click to expand...
Unless you want to gate...
 
I prefer to add an iso transformer going to the key of the gate rather than messing with the tone of the loop.
 
Jack Luminous said:
I prefer to add an iso transformer going to the key of the gate rather than messing with the tone of the loop.
Click to expand...
I am sure that loop is great for effects, but i literally only put a gate in the loop, and it is useless in a parallel
 
OK I get it ! Just an additional inline insert for the gate is needed in the loop before the parallel part. That's exactly what I do ! I have an AMT noise gate in line just before the loop interface.
 
Jack Luminous said:
The perfect loop already exists, it is this device :

P1010005.png

%E5%90%8D%E7%A7%B0%E6%9C%AA%E8%A8%AD%E5%AE%9A.png


It is a parallel loop with kill dry, bypass function and send/return levels. It can handle pedal levels as well as rack gear. Put this in an amp and it will be perfect.
Click to expand...

Yeah this is exactly why I have no plans of now going down the path of parallel functionality within the loop. There’s external options that exist already for those that want it and I have to prioritize the tone, feel, and transparency of the loop from the amp’s/players perspective, not the effects.

I can go down the path of parallel mixing and I even have a circuit in mind to do parallel mixing, but with high gain amps, it’s best I leave that as a separate problem. I may decide to offer a tube based outboard parallel mixer that accepts balanced XLR or phono single ended and offer that as an option.

The hard part has always been getting really low voltage out of really high voltage tone and it still sound and feel the same with the loop unbypassed. That is my priority. I also will be offering balanced out options for those that want it.
 
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Clipping circuit is designed and simulated for the return stage for single ended as intended. I design for a boatload of headroom on my effects loop return stage so if it’s clipping it’s way too hot of a signal. An LED will show clipping if you’ve set the threshold correctly for line or instrument and you’re sending a Vpp voltage that is twice the rated amplitude standard for instrument level or line level respectfully. That’s when the return begins to asymmetrically clip which will sound really bad given I’m using FETs.

Here’s an example showing the asymmetrical clipping at 3.5Vp input when line level is specified at half that value at around 1.75Vp. The vertical line is the immediate current draw through an LED.

IMG_6259.jpeg


This clipping circuit is intended for single ended return of line or instrument level.

On my todo list is to design a balanced return circuit and the associated line level clipping circuit. I don’t think I’m going to bother with an instrument level clipping circuit for balanced XLR return since most gear that’s balanced XLR isn’t instrument level to begin with? At least it doesn’t make sense to me to provide it unless you believe it’s necessary
 
The final part of the effects loop hardware design is completed! The whole effects loop is now designed from send to return on paper and simulated for correct design functionality.

Features include:

Send -10dBV/4dBu, return -10dBV/4dBu so you can send and return different levels separately

Clipping LED for both -10dBV and 4dBu.

Changing from -10dBV/4dBu on return adjusts the whole design so the amps volume stays the same if you’re sending the correct signals. You don’t lose insane headroom just because you’re using instrument level. They’re identical.

Pull send level knob to override -10dBV/4dBu fixed values to create your own custom value.

XLR balanced send and return options available either using XLR female plugs or stereo phono jacks.

Trails switch for toggling only send and maintaining return or turn off trailing to turn off send and return at the same time.

True bypass switch to defeat the loop completely.

Below is XLR balanced line level return to master volume input at 4KHz.

Notice no phase issues and no jitter, noise, or other problems. Crystal clean and stupid fast.

I’m excited to start PCB design and layout to now make it as compact as possible.

This will be the ultimate, largest sounding yet most transparent effects loop anyone has ever heard.

IMG_6268.jpeg
 
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