Help needed with FX loop tone suck!

[guitarman3001]

I've had my TC50 for a few weeks now and it's almost perfect. I haven't stopped playing it since I got it. But although it's almost perfect, it's not entirely perfect. I'm getting some very noticeable tone suck whenever I use the FX loop.

My regular setup is a Pedalsnake and two pedals in the loop. I thought it might be the Pedalsnake or one or more of the pedals so I used a process of elimination and tried everything on its own, and tried using regular cables instead of the Pedalsnake. The only time I didn't notice any tone suck was when I ran a short patch cable directly from the TC50's FX send to the FX return. A longer cable by itself from the FX send to the FX return caused some tone loss too. It wasn't as bad as with the full pedal setup but it was there.

I tried buffered pedals, true bypass pedals, placing the buffered pedal first, placing it last, using only one pedal in the loop (tried buffered and TB pedals alone), the Pedalsnake, regular 20' instrument cables of different brands (Hosa, Planet Waves, Rapco, etc...) and no matter what, even with just one pedal in the loop, either buffered or true bypass, there is significant tone suck. It's like someone threw a blanket over the speaker cab.

Also, in order to rule out my pedalboard setup, I tried the exact same setup with four other amps including another Mesa. A Rectoverb 25, a Roland Blues Cube Artist, a Friedman Runt, and a Peavey C20MH. With the exact same setup through those amps' FX loops there is zero noticeable tone loss.

I posted on another forum and a couple of other people said they were experiencing the same thing with their TC50s, but several others said they weren't noticing any tone loss through their FX loops. The difference seemed to be that those who didn't experience any tone suck were using high end line level processors like Fractal and Line 6 HD units.

A Mesa customer service rep posts on that forum and I emailed him but the reply I got, although incredibly fast, didn't provide me with much helpful info. He mentioned setting the channel masters for unity gain and that if that didn't fix it, the cause would be loading from the FX, cables, etc... I tried the channel masters and the master output at levels ranging from very low to very high (had to use an attenuator at the high levels) and nothing I tried eliminated the tone suck. If it was something else in my setup I'd expect to have the same problem with my other amps, especially the other Mesa. :?

The only solution I've found so far is to put an EQ pedal in the loop and adjust it to bump the high frequencies that are lost when using the loop. By doing that I can get the tones with the loop on or off to sound pretty close to the same but it's kind of a pain having to add another pedal in the loop just to offset the tone suck.

The TC50's loop is supposed to be buffered and I was under the impression that a buffered loop shouldn't suffer from this kind of tone suck, although I admit I don't really understand this all that much so I could be wrong about that.

The biggest mystery for me is why I'm only getting the tone suck with the TC50 and not with any of my other amps, which seem to work perfectly and have no tone suck when using the same setup with their FX loops.

Since the TC50's loop is tube driven, could it be a problem with the tube?

Any suggestions or ideas?

Here is a video where you can see and hear the difference when I have the loop on or off and the EQ pedal on and off.

Sorry, not sure how to embed videos on here so here's the direct link - https://www.youtube.com/watch?v=saKIM61nNwA

 

[jnoel64]

V5, which is the AT7, is supposed to be for the FX loop. I find it odd that the tube would fail so soon, but definitely give that a shot. If you have one, try a JAN-Phillips AT7. Those are military grade and should be an improvement over the stock Mesa. Although, I think using a non-Mesa tube could void your warranty. I use a G-Major 2 in my effects loop and have never had a tone issue. I also have a couple pedals I run in front of the amp and use an Emerson Concord buffer with those, just in case. Never had any tone loss with mine. Other than the tube, I would guess the only other suspects are the pedals themselves. Not all toys play well with each other.

What happens when you run your pedals in the front of the amp?

 

[Daxman73]

Yeah, pretty much what jnoel64 said. I don't have any tone loss with mine and I use 21' cables (Monster). My first thought as well would be the 12AT7. Let us know what you find out.

 

[bandit2013]

Perhaps you have something going on there but was uncertain your recording source was moving or not. In some instances I did notice a level drop once the FX loop was turned on but after it was active for a while I did not hear a change when it was turned off. After the third time watching your video I noticed a pattern that the signal level dropped when the loop was tured on and when it was turned off I heard the same level drop. I had to watch the video several times to get a better idea of what was going on. Almost sounds like loading on the FX line is causing a drop but it seems to rise gradually and when the loop is turned off it drops again. I would definitely check if any of your pedals have any batteries installed. Even if there is a DC supply in use, degraded batteries may cause issues if they are still in the pedals. Are you getting the same effect on CH1 and CH2? It is obviously evident there is a change in character in the signal level with CH3. I have not personally experienced this but sorry to hear you are having this issue.

I would suspect that the 12AT7 would be at fault here. This tube is always in the signal chain at all times. The TC-50 does not have a hard bypass that would bypass the signal from the 12AT7, the only circuit path that changes is the internal connection between send and return (also uses jack switches too).
I did recently have an issue with the Send circuit, lost all channels and no sound. However I was able to get a very clean sound if I plugged my guitar into the return jack (turned on FX loop too). I had a resistor open up on the Send circuit that prevented all channels from reaching the power tubes. I had tried a few other 12AT7 first before opening up the chassis to find what was the issue and found an open circuit across a 39.2K resistor. Replaced it and all is good. If you had the same issue your post would be quite different.....

Since I had repaired my TC-50 after it went dead (not totally dead as there was a very weak signal) I had to try the FX loop just for kicks. To rule out any so called high dollar effects or high quality effects (I generally use Strymon pedals) I opted to use the Line6 DL4 (this one is not as good as other pedals in my collection and does not work at all with the Mark V loop that is a line level signal) also used the longest effects cable I have (pro-co 12 FT double cable ) and was not very expensive. With the pedal active or in hard bypass I could not tell the difference with the loop turn on or off on all three channels. I did not discover any issues like you are having with your TC-50. No level drop on activation or deactivation of the loop, no notable difference in tone between active or inactive loop with the pedal on hard bypass. Even with the delay operating no tonal loss or level shift on any of the three channels.

 

[Liquid]

I have the same thing with the fx loop. It sounds like the volume drops a tiny bit or the sharpness. But its nothing raising the presence a smidge wont fix. I wasnt bothered by the minor difference with the loop on. I just figured it was normal because the signal has to travel through that much more of a circuit. I have a boss rc3 and an mxr cc delay in the loop and have tried the loop without anything and one pedal at a time with similar results. If you find the reason for your tonal loss post it here im curious. Thanks

 

[bandit2013]

I had mine working last night just fine... now the amp is dead so not much I can add at the moment. Talk about tone suck..... wow....

 

[Joshwah333]

I am also experiencing a tone suck when the Reverb is on and also when the FX Loop is on (even with nothing hooked up through the loop). It's slight, but noticeable.

Also, anyone experience that 50 watts isn't much headroom? I have a loud drummer. I am getting a much better volume response from my Mark V 35. I wonder if I just need to crank the master volumes on all channels and just use the Output for volume? The Mark V35 does not have an output knob, so I'm thinking this might be the way to go.

 

[bandit2013]

Which cab are you using? You could always opt for the 412 to move more air. I actually had to down size to a 212 cab as the 412 was too loud.

I play drums too... and I hit them hard.... I have practiced the drums with the amp running a recorded loop on a TC Ditto and found I have to drop the volume on my amps in order to hear what I am playing on the drums. Vertical 212 with reduced output if I am using the JP-2C set to 60W or the horizontal 212 with the Roadster running at 50W. I have not tried this with the TC-50 yet but will when the amp comes back from Mesa.

Speaker position is key if you want to hear yourself playing. Stand in front of the cab if needed. Don't stand in front of the bass drum.... You may need to reposition where your amp is located so you both can hear the guitar and drums. Please note a drummers perspective is far different than you think, I cannot hear the bass drum all that much, the toms are apparent as is the snare and cymbals but if there is a guitar amp facing you, that is all you hear which will cause the drummer to hit harder as they want to hear what they are playing as well as to be in sync with the other instruments. It is a battle who drowns out who. Try swapping places with the drummer. Sit on the throne and just use the kick drum pedal and have your drummer play the guitar at the level you have it at and see what happens. Also keep in mind what other instruments (guitar, bass, keyboard) is going to resonate in the drum set (unless it is electronic). I am sure somewhere in another forum there is a drummer making the statement I cannot hear myself playing, the guitarist has his amp cranked to the max and that is all I hear, my drums are not loud enough. Then the bass player may be doing the same in another forum.

 

[Joshwah333]

Which cab are you using? You could always opt for the 412 to move more air. I actually had to down size to a 212 cab as the 412 was too loud.

I play drums too... and I hit them hard.... I have practiced the drums with the amp running a recorded loop on a TC Ditto and found I have to drop the volume on my amps in order to hear what I am playing on the drums. Vertical 212 with reduced output if I am using the JP-2C set to 60W or the horizontal 212 with the Roadster running at 50W. I have not tried this with the TC-50 yet but will when the amp comes back from Mesa.

Speaker position is key if you want to hear yourself playing. Stand in front of the cab if needed. Don't stand in front of the bass drum.... You may need to reposition where your amp is located so you both can hear the guitar and drums. Please note a drummers perspective is far different than you think, I cannot hear the bass drum all that much, the toms are apparent as is the snare and cymbals but if there is a guitar amp facing you, that is all you hear which will cause the drummer to hit harder as they want to hear what they are playing as well as to be in sync with the other instruments. It is a battle who drowns out who. Try swapping places with the drummer. Sit on the throne and just use the kick drum pedal and have your drummer play the guitar at the level you have it at and see what happens. Also keep in mind what other instruments (guitar, bass, keyboard) is going to resonate in the drum set (unless it is electronic). I am sure somewhere in another forum there is a drummer making the statement I cannot hear myself playing, the guitarist has his amp cranked to the max and that is all I hear, my drums are not loud enough. Then the bass player may be doing the same in another forum.

I'm running it through a 4x12 slanted Mesa cab. I think you pinpointed one issue - I'm standing about about 7ft from the cab, it's behind me to the right. I'll move it next jam session and see if it helps.

I think I discovered another element while pondering this. The Mark V35 has NO output knob and only Masters for the 2 channels, while the TC-50 has Masters for each channel and a global Output knob. I would guess that I would need to max the Masters for the channels and use the output knob for more volume than the Mark V35. And I may not be able to even hear the difference until I'm around 3-4 o'clock on the Output knob.

My drummer is loud as hell, so he can be a challenge to play with sometimes. So I have a new rule that I crank it until everyone tells me to turn down. Amazingly, they still tell me to turn up sometimes. :lol:

 

[bandit2013]

Here is one solution to a loud drummer, get a JP-2C, Triple Rectifier or Road King II. All three should be able to drown out a loud drummer as well as the bass player and everything else in the room. I would not be fooled by the JP-2C 100W rating, it peaks close to 150W. I ran both JP and Roadster together and the JP drowns out the Roadster easily. I still have not found a way to get the drums louder than the guitar amp..... Must be something I am doing wrong, or that I have already damaged my hearing or both.

I am sure your band will be able to work things out.....

 

[Joshwah333]

I've decided to either get a JPIIC+ or wait until the next mark series comes out. Either way, it's a year out before I get another amp. I have plenty to keep me busy until then.

The TC-50 has a place in my collection - it's going to make a great classic rock/rockabilly/surf guitar amp when I eventually stop playing metal full time. But it's still a good amp for metal. Finally found a sweet spot with the MXR EQ, HI gain channel and Tight mode!

 

[golfnguitarz]

I've decided to either get a JPIIC+ or wait until the next mark series comes out. Either way, it's a year out before I get another amp. I have plenty to keep me busy until then.

The TC-50 has a place in my collection - it's going to make a great classic rock/rockabilly/surf guitar amp when I eventually stop playing metal full time. But it's still a good amp for metal. Finally found a sweet spot with the MXR EQ, HI gain channel and Tight mode!

I noticed you have a JVM as well. I would appreciate any insights between the two.

 

[Joshwah333]

The Marshall JVM is one of my favorite amps in my collection. I got a slamming deal from a rich guy who was a drummer on Craigslist. It came as a half stack with the matching 1960 slant cab. Got the whole package for $1500!! He was a drummer that wanted to learn guitar and decided that a Marshall JVM half stack was a good first amp choice. Lmfao!

I play my Mesa's at home, and the JVM remains at our band’s rehearsal space as don’t gig with it. Trying to keep my gig rig light. The tones that come out of this, especially when paired with my Stratocaster or Les Paul, are glorious. I would go as far to say, that because of the EL34 tone from the JVM, it inspired me to buy the TC-50. Ironic that I prefer the TC-50 with 6L6’s! I’ll have to give the EL34’s another run soon…...

The JVM can hit the tone realms (clean, crunch, OD) of the TC-50 and more. I would say that the overdriven tones on the TC-50 are a little more smooth and the JVM is more raw. As far as metal tones, the JVM sounds super brutal with a scooped MXR 10-band EQ through the loop and played through a Mesa Straight 4x12. Channels 3 and 4 are voiced with a different midrange frequencies, with channel 3 being voiced with a higher frequency and channel a lower frequency giving you a broad range of overdriven tones.

The JVM has 4 channels and 3 modes each – that’s 12 tones total. I cannot change tube types, as with the TC-50, nor does it have cab clone or headphone out, but it does have midi which I have yet to explore. The JVM also has Series and Parallel effects loops, so you’ve definitely got some effects routing options. One of the coolest features of the JVM is that you can program the 6 button footswitch to select almost any feature on the amp. And the footswitch stores the selections, so if you play another JVM, no need to reprogram! It is a home run for Marshall - no wonder they haven't improved upon it yet.

 

[Deadpool_25]

I am also experiencing a tone suck when the Reverb is on and also when the FX Loop is on (even with nothing hooked up through the loop). It's slight, but noticeable.

Also, anyone experience that 50 watts isn't much headroom? I have a loud drummer. I am getting a much better volume response from my Mark V 35. I wonder if I just need to crank the master volumes on all channels and just use the Output for volume? The Mark V35 does not have an output knob, so I'm thinking this might be the way to go.

I’m planning on doing some testing on the fx loop thing soon. My Invective does the same thing. Slight volume drop with fx loop on. Doesn’t really bother me but does make me curious.

On the volume thing, I’m not sure how the solo boost works. I guess it could be actually boosting the signal somehow but if it works by holding some of the amp’s normal potential max volume in reserve, then a perceived lack of headroom or volume might be solved by running with that boost on all the time. Of course, then you wouldn’t have it available to actually boost your solos but that could be solved with an external EQ pedal (which is probably a better way to solo boost anyway since you can emphasize frequencies that cut better if you want). The Invective has a master boost which is basically the same thing. People were saying it doesn’t get as loud as it should being 120W. But people were testing it with the master boost off. Turn that on and up and the amp gets very loud, very fast.

 

[bandit2013]

Hmm, :roll: I doubt my TC-50 is an exception but even after repair of the amp it still sounds as good as it did out of box. I have no tone or volume issues using the loop. It could be the gear used vs the amp. Sure that may be different with other amps and that I would expect since each amp may be different in its design and how it manages the loop signals. I have plans this coming weekend to compare signal levels of the Mark V to the other amps since I will be borrowing the oscilloscope I picked out for use as I was given the opportunity to spend $20K for engineering expenses this past year. It does not belong to me but I can borrow it if I need too. I am curious to see what the level changes are with some effects, but for tone and frequency response may be a bit more difficult or time consuming. I will also have to borrow the signal generator so I can keep a constant frequency and signal level for the evaluation use on the input of each amp. This may be interesting or may be utterly boring but at least it gives me something to do while on the Thanksgiving 4 day weekend.

 

[Deadpool_25]

Well I made the “mistake” of pretty much finishing my stereo rig. TC-50 + Invective + a handful of pedals. Good lord it’s glorious. Now I don’t know if I’m getting any tone suck at all anymore but if so it’s going down from ungodly to just godly lol. When I get the MIDI functionality up and running I’ll be able to test it out easier but I’ll do so out of curiosity. The rig sounds absolutely immense.

 

[bandit2013]

I have a theory on why some are having issues. for one it could be number of pedals, length of cable runs, type of cable, crappy batteries (some pedals use batteries and even if they are installed and using external power supply, if the battery is weak it may affect the performance of the pedal). As is the case with amps, not all effect pedals are created equal. Sure I am as picky as the rest of you when it comes to the signal chain and want no loss of signal (tone or volume) when using the FX loop. When it becomes amp related, it compounds the issue. However, my theory is simple. How would you know if the pedal in use is not phasing the dry signal from the effect? The obvious would be drop in volume and tone when the effect is active vs set in hard bypass. I would not make any difference to the amp if there was a phase shift on the signal if the amp is using a series loop. Most important is the loading on the send and return lines, so the impedance of the send should be appropriate for the signal being delivered. Send impedance should be low and the return impedance should be high. If you have an impedance miss match the issues will be apparent, the obvious would be trying to drive an instrument level device with line level signal as is the case with the Mark V. I have not had any issues with the following amps using instrument level effects in the loop: JP-2C, TC-50, RA100, Roadster, Mark III, Mark IV. The only black sheep of the heard so far was the Mark V. The effects loop on that amp is not very good and is difficult to manage even with the line level shifter. I have been able to use the line level shifter with the TC-50 without any signal loss which was a surprise as I expected the reduction in signal level would be of concern to the instrument level pedal (test unit was the Line6 DL4, not one of my favorite pedals).

I will attempt another test today if at all possible as I have borrowed some gear from work that will help reveal the truth of the FX loop. Not sure if this will prove anything. Test plan, use a function generator at 1Hz sine wave signal at instrument level, driving the input of the amp. Monitor the FX loop Send signal level as well as the Output to the speaker with a differential probe and a current meter. If there is a change in the output it will be revealed in the current level or voltage amplitude. I was going to do this first with the Mark V as that is the one amp that is more problematic due to its signal levels.

 

[mace]

“The only black sheep of the heard”

Not sure if this was an intended pun or not, but it was a good one.

It will be interesting to see what you find out with the scope on the Mark V and TC50 EFX loops.

 

[bandit2013]

Yes, it was intended to be a pun.

There is some interesting stuff I have measured this weekend. It is obvious that the Mark V send levels are line level. Oh boy are they.... However, the TC-50 has a stout drive on the send level too. The clean channels of the amps I looked at revealed the truth of the signal level ranges. Since the higher gain channels will compress the signal considerably due to distortion my findings on the TC-50 and the JP-2C will remain below 0dBu no matter how hard you drive the gain or channel volume (TC only, JP-2C uses the channel volume as the master and is not linked to the send level anyway). The highest signal level recorded was with the TC-50 clean channel with the channel volume and gain maxed out. Almost nearly enough to clip a strymon pedal in the FX loop at +8.17dBu. Strymon DiG, Brigadier, Big Sky max at or will clip at levels above +8dBu. I doubt I will ever run the clean channel that way but may have to see how it sounds just for kicks. The gain setting maxed out is a definite but not the channel volume.

There is a device called the line level shifter made by Ebtech. I got it for the Mark V but it does not work so well with that amp due to the send level drive impedance. I was able to use the Line6 DL4 with the Mark V and not overdrive or clip the input buffer but the end result was not much effect in the signal. Also the Ebtech LLS-2 reduced or loaded the send output by 23%. Definitely noticeable when turning on or off the FX loop. At least for the case with the TC-50 there was no signal reduction or loading on the send level. I was able to use the Ebtech LLS-2 with the TC-50 with no ill effects on send level or notable change in volume between FX on or off. That was surprising as I expected the level to be closer to instrument than it actually is. However if using a strymon product in the FX loop or even a Boss DD-500, Terra Echo TE-2, you will not be able to overdrive the input buffer. Not sure on signal integrity with the Boss gear (except for the Terra Echo as I have that). The initial focus was on the Mark V but I did include the TC-50 and the JP-2C following the third post or somewhere thereafter.

http://forum.grailtone.com/viewtopic.php?f=33&t=74195

 

[screamingdaisy]

I have the same thing with the fx loop. It sounds like the volume drops a tiny bit or the sharpness. But its nothing raising the presence a smidge wont fix.

This is what I had. Kind of sounded like a volume drop but attempts to adjust the volume back to unity were elusive. Best I can figure out it was a shift in the mids, and volume adjustments won't fix that.

TC-50 -> Strymon El Capistan using two 20 foot cables.

I wound up fixing the problem by putting the delay on top of the head and using a couple of short 18" patch cords.

I posted on another forum and a couple of other people said they were experiencing the same thing with their TC50s, but several others said they weren't noticing any tone loss through their FX loops. The difference seemed to be that those who didn't experience any tone suck were using high end line level processors like Fractal and Line 6 HD units.

The shift in tone is only going to affect those who are using the footswitch to bypass the loop since it's inserting/removing a whole bunch of circuitry/cabling/buffers/etc into the audio path. If you switch the effect on/off at the processor there will be no shift in tone since there's no changes being made to the audio path.

A lot of the guys using multi-effects processors are likely leaving the loop on all the time. Switching the loop on/off will kill their delay/reverb trails and effects spillover when changing presets.

In a way Mesa gets punished for trying to provide a purist option. If they just left the loop on all the time no one would notice the difference. But, because they provide us with bypass options and a way to easily A/B the two sounds people will pick up on the details every time.

The biggest mystery for me is why I'm only getting the tone suck with the TC50 and not with any of my other amps, which seem to work perfectly and have no tone suck when using the same setup with their FX loops.

Every Mesa I've ever owned has had a loop that sucked tone, the difference has largely been how perceptible the changes were and how easy it is to A/B the loop against the bypass sound.

My theory is that with the TC-50 being brighter and having more upper midrange than your typical Mesa the small shifts in sound in that part of the frequency spectrum become much more noticeable.

I also suspect it's also a different effects loop design since the master volume/solo are always on and can't be hard bypassed like in previous amps. I don't know what changes that's prompted to their switching and/or design logic.