# Guitar amp effects loop with only one jack: How does this work?
**URL:** https://boards.straightdope.com/t/guitar-amp-effects-loop-with-only-one-jack-how-does-this-work/1026667
**Category:** Cafe Society
**Tags:** music
**Created:** [January 13, 2026, 11:37pm UTC](https://boards.straightdope.com/t/guitar-amp-effects-loop-with-only-one-jack-how-does-this-work/1026667 "2026-01-13T23:37:51Z")
**Posts on this page:** 6
**Page:** 2
### Author:  [@Mister\_Rik](https://boards.straightdope.com/u/Mister_Rik)
#### Post date: [January 17, 2026, 12:31am UTC](https://boards.straightdope.com/t/guitar-amp-effects-loop-with-only-one-jack-how-does-this-work/1026667/21 "2026-01-17T00:31:36Z")
> [@CaveMike](#):
>
> Consider it took us 119 more years to invent USB A connectors with the innovation that it requires an average of three attempts to plug in a connector that only has two options.
A meme I saw some years back showed a USB A plug with the caption, “50% chance to get it right. Get it wrong 80% of the time.”
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### Author:  [@Mister\_Rik](https://boards.straightdope.com/u/Mister_Rik)
#### Post date: [January 17, 2026, 12:52am UTC](https://boards.straightdope.com/t/guitar-amp-effects-loop-with-only-one-jack-how-does-this-work/1026667/22 "2026-01-17T00:52:23Z")
> [@Eonwe](#):
>
> Note that the signal coming in from that loop doesn’t pass through any amp that you have output control over (this is… not great design). There is no knob on the amp that increases or decreases the level of the signal coming in from the EFX return.
>
> All that is to say, other than amp design, there is no inherent reason why you would need to have signal running into the main input in order to hear something coming in on an FX in. It’s just another input. It all depends on where that input comes in in the signal chain. On this specific amp it looks like that input is post-amp, and so there is no way to adjust the ultimate output level of that signal. have no idea if the Boss Metal Zone output is hot enough to be heard.
From what I understand, the FX loop is (typically) between the preamp and the power amp. The reasoning being that some types of effects (mainly time-based effects, like delay, flangers, phasers, etc.) work better _after_ all of the other signal processing is done. A lot of guitarists eschew distortion pedals and just overdrive the (pre)amp instead (or if they use a distortion or overdrive pedal, it’s mainly to boost that signal). So if you run the delay or what-have-you directly into the preamp, all of those effects are going to end up distorted by the overdriven preamp, which most players don’t want. So instead, you insert those effects _after_ the distortion/overdrive/EQ, and then everything gets fed into the power amp to make it all louder.
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### Author:  [@wguy123](https://boards.straightdope.com/u/wguy123)
#### Post date: [January 17, 2026, 1:10am UTC](https://boards.straightdope.com/t/guitar-amp-effects-loop-with-only-one-jack-how-does-this-work/1026667/23 "2026-01-17T01:10:54Z")
I think you have that right. I also found that on my bass amp, when the input jack was broken, I could use an external “pre-amp” and run it into the return on the loop and bypass the pre-amp and just use the power amp. It worked pretty well and I’m looking into getting a more versatile “real” pre-amp to get more amp models out of my amp (I’ve since had my amp repaired so I can use the built-in preamp and EQ section.
Also, seems like you dropped off here for quite awhile, but maybe I didn’t notice you. If you did, welcome back!
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### Author:  [@DCnDC](https://boards.straightdope.com/u/DCnDC)
#### Post date: [January 17, 2026, 2:05am UTC](https://boards.straightdope.com/t/guitar-amp-effects-loop-with-only-one-jack-how-does-this-work/1026667/24 "2026-01-17T02:05:37Z")
> [@Eonwe](#):
>
> have no idea if the Boss Metal Zone output is hot enough to be heard.
That’s actually how it’s supposed to be used, and a big part of why so many people think it sounds crappy.
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### Author:  [@Pork\_Rind](https://boards.straightdope.com/u/Pork_Rind)
#### Post date: [January 17, 2026, 2:17am UTC](https://boards.straightdope.com/t/guitar-amp-effects-loop-with-only-one-jack-how-does-this-work/1026667/25 "2026-01-17T02:17:08Z")
> [@Mister\_Rik](#):
>
> A meme I saw some years back showed a USB A plug with the caption, “50% chance to get it right. Get it wrong 80% of the time.”
I particularly liked the orientation chart labeled, “No. No. Yes.”
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### Author:  [@Mister\_Rik](https://boards.straightdope.com/u/Mister_Rik)
#### Post date: [January 17, 2026, 10:19am UTC](https://boards.straightdope.com/t/guitar-amp-effects-loop-with-only-one-jack-how-does-this-work/1026667/26 "2026-01-17T10:19:00Z")
> [@wguy123](#):
>
> Also, seems like you dropped off here for quite awhile, but maybe I didn’t notice you. If you did, welcome back!
I’m mostly over on Quora the last few years. It has a different format than the SDMB–it’s a “question & answer” site rather than a “discussion forum”. It can be rather hit & miss as to whether anybody with the appropriate knowledge will even see a particular question (they’ve installed an AI “prompt generator”, and questions from real people can get lost in the flood of nonsensical questions the AI generates). The Q&A format itself isn’t really suited to long-form discussions, and there’s a limit on the length of the questions themselves, so you can’t really put all of the relevant details into your questions. So I still pop in here every now and then.
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