Series vs Parallel efx loop?

[Woody Sound]

I just bought a fairly high end 2-channel tube preamp/overdrive. It has a built-in efx loop, with a toggle for series or parallel loop. I have never heard of such a thing. How do they differ? How do I know which one to use? The manual doesn't really say much except that you have the ability to switch it.

[mikeSF]

Series means the entire signal comes out(of the preamp section), goes into your effects, and then returns to the amps power stage. A series loop is perfect for overdive and compression since you typically dont keep any of the dry signal.

A parallel efx loop sends a split signal out that can be effected and then mixed back with the original. Better for reverbs and delays. It's the gentlemen's effects loop.

[Woody Sound]

Thanks Mike. So the obvious next question is, which kind of loop do most amps have? For example, Quilter?

[Rodney Gene]

Thanks Mike. So the obvious next question is, which kind of loop do most amps have? For example, Quilter?

In general, most amp effects loops are series or serial loop (including Quilter). Good for anything you want use to bypass the pre-amp section (time based effects).
The majority of 'working mans' amps made are not equipped with parallel loops options.

[Cavalier]

You can of course make a series loop parallel in a number of ways. Y cords to add a dry line, use a mixer etc .. you can also do different effects each leg if you wanted etc.... some of the programmable multi efx can do this and save and switch settings.

[mikeSF]

Thanks Mike. So the obvious next question is, which kind of loop do most amps have? For example, Quilter?

hopefully you were able to look up your specific Quilter model and find out. My google search said Quilter offer parallel loops with a blend control but YMMV.

Of the amps i'm looking at in my music room, there's a Acoustic Image Clarus which has a parallel loop with mix knob.
I also have an 80's Carvin Quad-X with more than one of each. That is, each of 4 channels has it's own series effects loop, and then the reverb and master loops which are global to all channels are parallel, each with a blend control. That pre amp is slick!
Lastly, I have Kemper profiler which will do anything you ask of it, and I'm pretty sure both types are represented; I personally do not use any outboard effects with mine, so have never tried it.

[Rodney Gene]

My google search said Quilter offer parallel loops with a blend control but YMMV.

AI search is an unfortunate reality all of us have to deal with during this current development phase of Googles search results. Quilter amps do not have parallel loops (no blend or mix knobs is the biggest giveaway). But a couple of the current new digital pedals (the Neunaber / Quilter) can be setup for stereo or used within a parallel loop environment with the built in kill switch... and the new Quilter/Nuenaber Elevate pedal can basically mimic a parallel loop in function using the built in effects/settings.

[mikeSF]

That's too bad about quilter. I actually do have one of those pedals whose purpose is to create a loop. I'm trying to sell it on reverb right now since I don't need it anymore