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

[Smash]

The perfect loop already exists, it is this device :

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.

Unless you want to gate...

 

[Jack Luminous]

I prefer to add an iso transformer going to the key of the gate rather than messing with the tone of the loop.

 

[Smash]

I prefer to add an iso transformer going to the key of the gate rather than messing with the tone of the loop.

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

 

[Jack Luminous]

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.

 

[glpg80]

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.

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

 

[glpg80]

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.

 

[glpg80]

Next steps will be a double sided PCB

 

[glpg80]

I have figured out a solution to offer parallel mixing with a kill dry switch!

I plan to offer 3 integrated effects loop stages to choose from:

Stage 1:

- Single ended to single ended independent line and instrument level control switches for send and return.

- A send level knob that you pull to override the instrument or line level send switch.

Stage 2:

The second stage includes stage 1 options in addition to a clipping LED and supporting circuitry for the single ended effects return.

Stage 3:

The third and final version includes stage 1 and 2 options in addition to:

- The ability to accept return balanced line level with a stereo return jack or an optional XLR jack.

-Parallel mixing knob with a switch for kill dry that completely removes the parallel mixing circuit so that it operates 100% wet just like a series effects loop.

- Never offered before, when you enable the parallel mixing, you also have a switch to change the phase of the dry signal 180 degrees for best audio quality. This means you can also use a loop back cable to match the phase of your amp with another amp that has more or less gain stages.

Fresh new designs take time. I appreciate everyone’s patience as progress is made!