Series/parallel fx loop: really simple or what?

[alfi27]

Hey boys,

Sorry for starting a dozen new threads, maybe I should just have one thread with all of my questions? If that would be better I can turn this thread into that

Anyway, I'm currently working on a new amp design and the fx loop needs to be great. The starting point will be something like a Metro Zero Loss design, or maybe the Friedman loop. They might be very similar or identical, I haven't studied them that much.

The loop will be footswitchable and have a return level knob so it can be used as a lead/volume boost as well, and there is space for one switch on the chassis. The contenders are active/bypass, line/instrument level and series/parallel.

Which brings me to the billion dollar question, is a parallel loop simply a series loop where the signal is being split where the bypass switch usually is? As in, 50% of the signal goes to the send jack and 50% past the loop? Or will most of the signal naturally take the path of least resistance; which I asumme would be the bypass path? I'm thinking some extra stuff might be needed in the signal path to make it work like that?

This is an amp that I hope to sell a few copies of, so this is more about what the average guitarist wants and needs than what I personally want and need.. Any input at all would be greatly appreciated, thanks!

[tubeswell]

Which brings me to the billion dollar question, is a parallel loop simply a series loop where the signal is being split where the bypass switch usually is? As in, 50% of the signal goes to the send jack and 50% past the loop?

Parallel loop keeps a permanent ‘dry’ signal pathway, which the FX loop is in parallel with.
Series loop breaks the dry signal and inserts the FX loop between the break.

Good luck with selling your stuff. Make sure you’ve got some personal liability insurance.

[alfi27]

Thanks man. What you said is basically what I tried to say, but less successfully... So it is that easy? Series = all the signal is going to loop send. Parallel = "half" of the signal is going to loop send, and half is omitting the loop? Obviously I could, and probably should just try it when I get to the point of wiring up the fx loop, and then decide what the switch will be doing. If parallel is that simple and it turns out to be a useful option, I could also put in a 3 way bypass/parallel/series switch.

Interesting what you're saying there, I looked into CE approval and that stuff is really expensive... I do have a fairly unrealistic hope that when I post a demo video of it (that obviously has to be really good) on Youtube and market it, it will "blow up", but if I don't have stuff like liability insure in order that could really backfire. If the amp turns out as great as it is in my head, I think it has potential to become successful. Shortly summed up, it is a 2 channel 50w amp with some cool features in a lunchbox-ish enclosure, that is small and light enough to bring as carry on; on the plane.

[tubeswell]

Liability Insurance is there to protect* you against being sued for negligence by a victim's lawyer if they die of electrocution using your amp. It doesn't deal with professional registration, which you need in order to even get liability insurance.

* Up to a certain price point - whatever the insurance policy states that they will cover you for in legal expense claims. (These policies typically require you to be a professionally registered certified electrical engineer as a prerequisite).

[xtian]

Devil here. "Series" and "parallel" are very basic concepts in electronics. Do you have any electronics expertise?

[jjman]

The way BF/SF reverb works in Fenders can be looked at as a parallel loop. However, they have reduced bass and a transformer in the "loop" path. And the spring tank itself which is the "effect" in the "loop."

[alfi27]

Devil here. "Series" and "parallel" are very basic concepts in electronics. Do you have any electronics expertise?

I am very familiar with those concepts indeed, and that is not the issue. Having worked exclusively on vintage Marshalls, I'm not terribly familiar with fx loops. As it seems to be near impossible to explain and I don't have the time to make a drawing, I'll ask: how would you turn a buffered series fx loop into parallel? Would you add any components, or just do a simple rewiring?

[10thTx]

Did you try "search" ?

https://ampgarage.com/forum/viewtopic.php?f=5&t=21205

https://ampgarage.com/forum/viewtopic.php?f=5&t=10477

https://ampgarage.com/forum/viewtopic.php?f=5&t=21003