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

[glpg80]

I'm working on a brand new effects loop design intended to be used exclusively for high gain amplifiers.

What features do you want in an effects loop? What do current offerings lack sonically to you? I have my own ideas of course but I’m interested in what others think as well!

 

[Smash]

I'm working on a brand new effects loop design intended to be used exclusively for high gain amplifiers.

What features do you want in an effects loop? What do current offerings lack sonically to you? I have my own ideas of course but I’m interested in what others think as well!

Series obviously. Anything else, i dont know enough to say.
I didnt like the loop on my wizard. I LOVE it on the MGL, but i know nothing of how it is designed.
Randall rg150h.had perfect loop also

 

[glpg80]

Series obviously. Anything else, i dont know enough to say.
I didnt like the loop on my wizard. I LOVE it on the MGL, but i know nothing of how it is designed.
Randall rg150h.had perfect loop also

I hate the metroloop and totally get where you’re coming from! Great feedback

Loops and high gain are not as easy as they seem at first glance.

 

[Smash]

Series obviously. Anything else, i dont know enough to say

I really know nothing about loops. The only thing i know is that parallel is probably cool as fuck for rock and below. But it is absolutely useless for gates. Absolutely hated the loop on the twin jet.

The wizard i got a ground loop on the loop forst time i tried it, and so just left it off.

But i would read anything you think about loops. Like what is benefit of tube buffered? What is the metro loop characteristics compared to others? I believe it is serial.

 

[7704A]

A neat thing I saw, which I'm not sure will translate to high-gain 'n gates, was allowing the switching of the loop input so that you do some crazy solo with time-based effects in the loop, switch off the input to the loop but still mix in the output, and now you have delay trails underneath the sick riff you pivoted to.

 

[glpg80]

A neat thing I saw, which I'm not sure will translate to high-gain 'n gates, was allowing the switching of the loop input so that you do some crazy solo with time-based effects in the loop, switch off the input to the loop but still mix in the output, and now you have delay trails underneath the sick riff you pivoted to.

Love the idea. To minimize pops and to get a better transition I may use FETs for this feature and of course it would have to be attached to a footswitch. Would you prefer effects loop on/off be only input mute/unmute and the output always connected? Would you also want true bypass on the footswitch or only on the amp or both?

Send level and return level both or either or?

 

[7704A]

Would you prefer effects loop on/off be only input mute/unmute and the output always connected? Would you also want true bypass on the footswitch or only on the amp or both?

Send level and return level both or either or?

Those would be questions for more experienced gigging musicians.

My limited-experience opinions: I don't know if I'd want the output always connected, though I'm having a difficult time thinking of non-pathological examples where I wouldn't. For true bypass I don't care as long as the sound isn't mucked with by whatever scheme, and ideally the footswitch would be a standard passive one for easy replaceability. Or the protocol documented in the manual if a new footswitch needs to be built after production ceases.

Edit: Also credit for the idea is Kevin O'Connor's, or at least that's where I heard of it first. Maybe he cribbed it from someone else.

 

[Epiplatys]

To be able to toggle it off, meaning to entirely defeat it/erase from the signal path with a flick of a switch. This can’t be overstated.

 

[SpiderWars]

I like them integrated such that the Return Level is a global master volume. I’ve even labeled them as such and put them on the front panel with Send level on the back next to the Send jack.

Just curious but what do you hate about the Metro loop? I thought it was generally well liked.

 

[glpg80]

I like them integrated such that the Return Level is a global master volume. I’ve even labeled them as such and put them on the front panel with Send level on the back next to the Send jack.

Interesting - I always hated that myself as my Bogner was that way. I only wanted the send and return levels to affect the effects loop but nothing else. Decoupled in a sense? Can you describe a reason why you’d want a global master? Maybe I just don’t use amps in the same manner or don’t understand why.

Just curious but what do you hate about the Metro loop? I thought it was generally well liked.

I sent you a PM

 

[SpiderWars]

Interesting - I always hated that myself as my Bogner was that way. I only wanted the send and return levels to affect the effects loop but nothing else. Decoupled in a sense? Can you describe a reason why you’d want a global master? Maybe I just don’t use amps in the same manner or don’t understand why.


I sent you a PM

Once I have the channels balanced I want to be able to control the overall volume of the amp. Some amps already have something like that, it depends on how the channel volume(s) are setup. But I prefer the final global volume control to be the Return Level. So I would dial in all the channel volumes and set the correct Send level, then the final Master of all master volumes is the Return.

 

[glpg80]

Update!

I’ve not yet landed on a topology component wise that I’m completely happy with. I’m leaning heavily towards all opamps as they are insanely efficient doing what we need them to do for effects loops. Low noise, excellent performance, transparency, etc.

I’ve been thinking heavily on the following features:

A switch that keeps tails on or off. So when the effects loop switch it toggled on the footswitch, the send is toggled, or the send and return are both toggled (effects loop true bypass)

An easy to find effects loop true bypass switch on the back of the amp which means you don’t need the footswitch to defeat the effects loop.

It will have a send level switch to choose from line level or instrument level that’s capable of driving super low impedances. If you pull a send level knob, it overrides the switch and you can vary the send level manually.

I will not be offering a return level knob that acts as an overall master. The reason is that typically you have the channel volumes after my effects return which are true channel master volumes and have nothing to do with effects levels themselves. As such the return level knobs are poorly implemented or redundant master volumes in my designs and to try to remove the redundancy does nothing beneficial tonally but negatively impact noise performance.

The effects loop will have the option to ground lift the send separate from the return. Meaning you can ground lift both effects send and return, only send, only return, or ground lift nothing. This is important for when your send and return aren’t the same piece of outboard gear and can help in removing ground loops caused by effects loops.

I plan to incorporate a clipping LED for when the effects return is being clipped.

I intend for there to be a series/parallel mix knob for mixing the return signal with the amp’s dry signal. This one’s actually the most challenging as it’s not quite as simple as it seems and also why some people hate them - they’re poorly implemented or just really hard to get right.

If there’s a feature I haven’t mentioned that you’d love to see, let me know

 

[glpg80]

So I’ve made some significant progress on this.

I reached out to a manufacturer and got a FET model direct from the company - I’m also in talks with the product manager to provide anything else I need.

I’ve been working on the send design and I plan to offer two levels of quality effects loops for various needs and features desired.

I now have a send/out using all FETs that is capable of sending balanced XLR out and still has send level controls as stated above. This version can also do single ended and the ground is completely isolated to prevent ground noise and ground loops from outboard gear.

I will have a much smaller footprint version that can send single ended only with send level controls and uses a simple ground lift switch.

Neither versions use LND150s which I personally don’t like the tone of.

Just wanted to say I’ve been working hard on this. Once I have the stages stable and the time domain simulations look good, I’ll move onto adding the above features.

 

[Smash]

I dont really understand the difference completely, so the first version..would it work perfectly with a noise gate then without needing an iso transformer? I am assuming serial

 

[glpg80]

I dont really understand the difference completely, so the first version..would it work perfectly with a noise gate then without needing an iso transformer? I am assuming serial

Yeah that’s totally my fault - I’ll type it better here. The first version uses an isolation transformer but it’s physically designed to be used with the amp’s signal. Think about a balanced XLR out for line level for use with rack gear, or flip a switch to change to single ended that still uses the isolation transformer for optimal ground isolation performance.

The lower end version doesn’t have the iso transformer or the balanced XLR out and the circuit is way less complicated - you get a ground lift switch instead.

Both still have the send level controls of line/instrument or pull the send knob to set a custom level.

This is just the send side right now. I’ll work on the return side next and that is where you typically design mixing stuff as well.

 

[Smash]

Yeah that’s totally my fault - I’ll type it better here. The first version uses an isolation transformer but it’s physically designed to be used with the amp’s signal. Think about a balanced XLR out for line level for use with rack gear, or flip a switch to change to single ended that still uses the isolation transformer for optimal ground isolation performance.

The lower end version doesn’t have the iso transformer or the balanced XLR out and the circuit is way less complicated - you get a ground lift switch instead.

Both still have the send level controls of line/instrument or pull the send knob to set a custom level.

This is just the send side right now. I’ll work on the return side next and that is where you typically design mixing stuff as well.

I think i am getting the gist. It sounds very complicated, but i may end up learning a ton about loops here. I thought of them in much simpler terms. But i suppose there is a reason i have seen so many different ones in older amps

 

[glpg80]

This is performance and progress so far!

The bottom right graph is Treble send to balanced XLR out at line level (or unbalanced send instrument level) and the top left graph is instrument level single ended return to master volume.

I still have to design the balanced line level return to master volume.

This is completed with all mosfets. No tubes however I do have a version that offers 12BH7A buffered balanced send XLR to add tube warmth.

A lot of care has been given to signal and feel transparency and utmost care to noise performance at line levels when studio rack gear is utilized.

Hoping to continue development and incorporate as many of the features/goals mentioned prior.

 

[Smash]

This is performance and progress so far!

The bottom right graph is Treble send to balanced XLR out at line level (or unbalanced send instrument level) and the top left graph is instrument level single ended return to master volume.

View attachment 399713

I still have to design the balanced line level return to master volume.

This is completed with all mosfets. No tubes however I do have a version that offers 12BH7A buffered balanced send XLR to add tube warmth.

A lot of care has been given to signal and feel transparency and utmost care to noise performance at line levels when studio rack gear is utilized.

Hoping to continue development and incorporate as many of the features/goals mentioned prior.

I really like the white scribblies

 

[glpg80]

I really like the white scribblies

White seemed most friendly. Red just seemed like angry coloring.

Jokes aside Insane amounts of effort and design to get those two graphs in only 2 months - the concepts nor circuits aren’t based on anything anyone’s seen before.

 

[Jack Luminous]

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.