#1
So, I was playing on my 6505+ 1x12 combo, and I realized it sounded very fizzy with wayyy too much presence and high end. Thing is, the presence was set to 0. Once I took out the FX loop, it sounded sooo much better. I actually put a pedal connector from send to return with nothing else there and it still made it sound very fizzy. Any ideas on what's causing this? And what could I do to fix it?

I mean, I play heavy metal, so an FX loop isn't NEEDED, but I've got a rack FX and I hate to see it go to waste.
#3
just put the rack before the preamp (into the input) instead of after (into the fx loop)
#5
I've noticed this with mine as well. It is indeed the effects loop causing it. I just compensate by turning down the highs and presence a bit and boost the lows (not too much) and I can get it pretty close to where it is without the effects loop.

I'd put everything in front of the amp, but I only use a reverb pedal and a Tubescreamer; the reverb sounds much, much better if it's in the loop.
Atmospheric dark metal w/ black and death metal influences:
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Pestilential Flood
#6
just to note. if u put your effects in the front of the amp, something like a chorus would actually modulate your guitar signal and change the pitch (cause thats what chorus emulates, is the pitch going slightly up and down very fast), but in the FX loop it wouldn't alter the guitar signal.

at least this is what happened to me when i put my chorus pedal in front then in the fx loop
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#7
Quote by EspTro
just to note. if u put your effects in the front of the amp, something like a chorus would actually modulate your guitar signal and change the pitch (cause thats what chorus emulates, is the pitch going slightly up and down very fast), but in the FX loop it wouldn't alter the guitar signal.

at least this is what happened to me when i put my chorus pedal in front then in the fx loop


This depends if its Series or Parallel, if its series it takes your signals and runs it through the wet mix and sending it wet, which will alter your signal, messing with your tone. If its Parallel it runs with wet signal and dry signal together without altering your signal, even though sometimes it can, depending if it has a wet/dry mix knob.

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Last edited by d.c.guitar at Nov 25, 2011,
#9
Quote by denied
Yep, effects loops will change the way your amp sounds.

They are dumb.


But, are all amps built that way? I would think that higher-end amps would have a loop you could use without any tone-suck.

And, they're not dumb. There are certain effects that you don't want running before the preamp, especially with overdriven tones. For example, my reverb sounds really harsh and muddy when run before the preamp, but in the loop, it retains my overdriven sound - but sounds like, well, reverb.

In any case, I've gotten around the issue on my 6505+ combo just by Eq'ing a little differently...
Atmospheric dark metal w/ black and death metal influences:
(My Soundcloud page):

Pestilential Flood
#10
Quote by KailM
But, are all amps built that way? I would think that higher-end amps would have a loop you could use without any tone-suck.

And, they're not dumb. There are certain effects that you don't want running before the preamp, especially with overdriven tones. For example, my reverb sounds really harsh and muddy when run before the preamp, but in the loop, it retains my overdriven sound - but sounds like, well, reverb.

In any case, I've gotten around the issue on my 6505+ combo just by Eq'ing a little differently...


no not all amps are built that way.

some amps have very good effects loops.
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#11
Quote by KailM
But, are all amps built that way? I would think that higher-end amps would have a loop you could use without any tone-suck.


Anytime your using an effects loop, your changing the way the amp sounds. Doesn't necessarily need to be tone suck, but it will sound different.

I'm by no means a tech - this is personal experience across many many amps.


And, they're not dumb. There are certain effects that you don't want running before the preamp, especially with overdriven tones. For example, my reverb sounds really harsh and muddy when run before the preamp, but in the loop, it retains my overdriven sound - but sounds like, well, reverb.


NSS

#17
The effects loop is driven by V3. Try a new tube in there. The driver is a cathode follower which taxes the tube quite a lot. Buy a good valve that is capable of running in that configuration (ie not a Sovtek, go for something decent like a JJ, SED or NOS)
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#18
^^Thank you Cathbard! So, a JJ 12AX7 in that position would improve the problem? Sorry, I'm a complete noob when it comes to tubes and electronics...
Atmospheric dark metal w/ black and death metal influences:
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Pestilential Flood
#19
Quote by KailM
^^Thank you Cathbard! So, a JJ 12AX7 in that position would improve the problem? Sorry, I'm a complete noob when it comes to tubes and electronics...


very good quality tube, if anything along the lines of that method will fix it, it will be that tube
Quote by kangaxxter
The only real answer to the SG vs Les Paul debate is to get a Flying V and laugh at all the suckers who don't have one.


Quote by Blompcube

if you embrace inaccurate intonation it can be quite arousing.


I <3 TWEED
#20
Quote by KailM
^^Thank you Cathbard! So, a JJ 12AX7 in that position would improve the problem? Sorry, I'm a complete noob when it comes to tubes and electronics...

Yes, a fine tube. When you unplug the FX loop V3 is bypassed. Try just a patch cable between send and return. That will tell you what V3's circuit sounds like. If it sounds dodgey you can be pretty sure that the tube is shot.
It's worth having a spare preamp tube anyway, even if just for fault finding so even if V3 hasn't gone you've lost nothing. I'd buy the tube anyway, it's not like they are expensive.
Gilchrist custom
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Marshall 1960A
Boss GT-100


Cathbard Amplification
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#21
Quote by Cathbard
Yes, a fine tube. When you unplug the FX loop V3 is bypassed. Try just a patch cable between send and return. That will tell you what V3's circuit sounds like. If it sounds dodgey you can be pretty sure that the tube is shot.
It's worth having a spare preamp tube anyway, even if just for fault finding so even if V3 hasn't gone you've lost nothing. I'd buy the tube anyway, it's not like they are expensive.


Thank you, once again. I might do this soon. I have tried just connecting the send and return of my FX loop with a short guitar cable and indeed, the tone alteration is still there. (I actually sold a chorus pedal a few months back because I thought it was causing the issue.) It doesn't sound like anything is wrong with the amp, it's just that without the FX loop engaged, the amp sounds a little "meatier" and richer, whereas with the FX loop in use, it's like it boosts the highs or cuts the lows/low mids a bit.

Again, it's not such a drastic difference that you can't tune some of it away with the EQ, but if a $10 tube change will fix it, I'm stupid not to.

Now, for a little more info - are the tube positions labeled inside the amp? I've never taken off the back plate to get a good look. My manual doesn't say much about the tubes or circuitry. Ultimately, I'll probably replace them all with JJ's, but I'm extremely limited on funds at the moment.

To OP, sorry if I hijacked this thread, but it sounds like you're experiencing the same issue. Thanks to all who responded in this thread!
Atmospheric dark metal w/ black and death metal influences:
(My Soundcloud page):

Pestilential Flood
#22
Not sure about the labelling but normally V1 is closest to the input jack and they count from there.
Gilchrist custom
Yamaha SBG500
Telecasters
Randall RM100 & RM20
Marshall JTM45 clone
Marshall JCM900 4102 (modded)
Marshall 18W clone
Fender 5F1 Champ clone
Atomic Amplifire
Marshall 1960A
Boss GT-100


Cathbard Amplification
My band
#24
Pretty sure it's the third one from the input jack.
Gilchrist custom
Yamaha SBG500
Telecasters
Randall RM100 & RM20
Marshall JTM45 clone
Marshall JCM900 4102 (modded)
Marshall 18W clone
Fender 5F1 Champ clone
Atomic Amplifire
Marshall 1960A
Boss GT-100


Cathbard Amplification
My band