Another TC-100 vs Badlander topic + a novel trick

[danielpasco]

I'm still lugging around my old 100 pound beast Electra Dyne 1x12 combo. It just sounds so good. I'm in a classic rock cover band and even the drummer said "how good my guitar sounded" lol.
It's always funny when someone goes to help me load in or load out and grab the amp! Holy sh!t this thing is heavy!

I still regret selling mine.

 

[Eevil]

I'm still lugging around my old 100 pound beast Electra Dyne 1x12 combo. It just sounds so good. I'm in a classic rock cover band and even the drummer said "how good my guitar sounded" lol.
It's always funny when someone goes to help me load in or load out and grab the amp! Holy sh!t this thing is heavy!

Had one of those narrow combos.. did not gel with the combo cab tone but the amp itself works and is glorious

 

[bandit2013]

Quite interesting set of responses on the TC100. My issue with the amp was that it kept losing output volume. It got to the point where the TC50 had more power than the TC100 at 100W. It was all due to the instability of the Chinese 12AT7. The JAN/Phillips 12AT7 made a huge difference and I restored that volume I had when the amp was new. Odd that I prefer the Chinese 12AT7 in the RA100 as it has a similar design. Tried the JAN/Phillips in the TC50 and that did not change anything.

If I have not stated before, the 12AT7 tube V5 is always in the signal path. The send circuit is a cathode follower with low output impedance and the recovery stage is the other triode of that tube. The FX on/off circuit is just a relay that shorts the send to return when something is plugged into the FX loop jacks. If you do not plug anything in, the return jack has a shorting switch to connect to the send so it is bridged internally. Turning on the FX loop or turning it off should not have any change in character. Just insert a jumper cable from send to return and see if that does make a difference when you turn on the loop or turn it off.

My cables are 10ft as well. I have several sets of this cable. I have yet to have issues in tone suck with any amp unless the gear is not compatible with line level signals.

https://www.sweetwater.com/store/de...trument-patch-cable-10-foot-straight-straight

I mostly use Strymon stuff as that was the only brand that worked with the Mark V90 FX loop without getting overloaded or suffer major tone suck or compression. I still have some of the units I experimented with that did not work well with the Mark V90: TC flashback triple delay, and Line-6 DL4. The TC unit was just a shift in tone, the Line-6 was more of a buffer overload issue as it compressed the signal so bad it had no detail in the effect. I did try something other than Strymon, a Source Audio Ventris. Its specs stated it would work with line level signals +8dBu. However, when I used it, the output level seemed to drop, it would go back to normal level if I turned it off. This issue was not just with the TC100 or TC50, I had the same issue with the JP2C and that signal level is not line level either. Perhaps I need to update the firmware or do something with the NEURO interface to correct the output. It is a decent unit, just did not maintain unity between input and output.

Some of the FX units may have some sort of configuration programming through a downloadable resource. If the input and output are not self adjusting to maintain unity in signal levels, you may have to adjust some parameters of the unit using the proprietary program to configure it. I need to see if I can get the Ventris to work better. If I could fix that drop in volume issue it would be a cool fx pedal to use.

 

[bandit2013]

@marcelomazzuco made a great video comparing cable lengths and use of some buffers. At first, I was not sure what I was looking at but I did see what he was doing here. I will buy that. He made some good points. Sure, long cable runs will affect the tone more so with the upper frequencies.

https://boogieforum.com/threads/mesa-triple-crown-tone-suck-test-new-video.88094/#post-542055

I should have asked if the Dual rec below the TC100 has any similar issues on cable runs.

 

[MarkIVWump]

I ordered a Jan/Phillips 12AT7 based on this recommendation and put it in the V5 of my TC50 and the volume of my FX loop started fluctuating and dying. I tried another 12AT7 I had lying around and the same thing happened. I put the Chinese Mesa 12AT7 back in and the FX loop works as fine as can be expected again. Any ideas what is happening?

Edit: Also one of the pins was bent on my original 12AT7 which I noticed someone else mentioning. Did they bend a pin on purpose for some reason?

 

[bandit2013]

Pins are not supposed to be bent. It may have been caused by its removal or how it was inserted. Best to verify by feel that the pins are aligned before pressing the tube into place. If they are not straight, it becomes more difficult to get the tube installed. Never force a tube into the socket.

Sorry you had issue with the JAN/Phillips 12AT7WC tube. Where did you get it from?

Considering the fire Shuguang had a few years back, 2018? whatever stock of the Chinese tubes were left, I am sure that inventory has been long gone. Mesa replaced the Chinese 12AT7 with the TungSol 12AT7. Not just for keeping up inventory but more so due to performance issues. I had inquired why the change with the Mesa TT800 as it came stuffed with the Tung Sol 12AT7. Someone from Mesa in one of the facebook clubs for Mesa bass amps, claimed the Chinese 12AT7 was not very reliable. The Tung Sol 12AT7 had more stability. Sure, fine in the BASS amp but they were super bright in the TC amps. I actually favor the Chinese 12AT7 in the RA100. TC is a bit different. It was the TC100 that I had issues with and much to what you described. The JAN/Phillps 12AT7 worked well and has been in there since I first mentioned it.

 

[MarkIVWump]

I got my JAN/Phillips 12AT7 from Ruby Tubes on Reverb. I tested it in another amp and it works so it's not the tube. And my other spare (unknown origin) 12AT7 works in other amps. My TC50 is from 2017 and it looked to me like no one had ever pulled the tube before, so it seems likely it's the Chinese 12AT7. Also, no matter what tube I had in V5, the amp functioned completely normal as long as I didn't turn the FX loop on.

I did just give the manual a thorough read through and found out that the TC50's FX loop level controls are the channel master volumes. I had been running all of them at noon and the manual says to keep the master volumes lower than noon for the FX loop to work properly.

By putting a more efficient tube in V5, could I have been running too hot a signal through the FX loop that caused some damage or a failsafe to trigger? My Mark IV also has this shared channel volume/FX loop level design and I've actually experienced something similar there when running a hot signal pedal through the FX loop with the channel volumes too high. The difference is there was noticeable distortion and crackling on the Mark IV but it did have a significant volume loss in the same way.

I will attempt trying the tube again today to see if it works running the channel volumes at different levels, but I'm curious, what channel volume levels is everyone running when they experience FX loop tone suck or inefficient volume? Is everyone aware that the manual states to keep the channel volumes between 9:00 – 12:00?

 

[jnoel64]

This is all very fascinating to me. I, too, found my factory Mesa 12AT7 in my TC50 had bent pins when I pulled the tube out of curiosity. I replaced that tube with a JAN Phillips 12AT7 and have had zero issues. Ever since the (in)famous AT7 "mod" for the Mark V90, I have stocked up a decent supply of those JANs. My V is long gone, but I still find lots of uses for that particular lower gain tube.

 

[bandit2013]

I got my JAN/Phillips 12AT7 from Ruby Tubes on Reverb. I tested it in another amp and it works so it's not the tube. And my other spare (unknown origin) 12AT7 works in other amps. My TC50 is from 2017 and it looked to me like no one had ever pulled the tube before, so it seems likely it's the Chinese 12AT7. Also, no matter what tube I had in V5, the amp functioned completely normal as long as I didn't turn the FX loop on.

I did just give the manual a thorough read through and found out that the TC50's FX loop level controls are the channel master volumes. I had been running all of them at noon and the manual says to keep the master volumes lower than noon for the FX loop to work properly.

By putting a more efficient tube in V5, could I have been running too hot a signal through the FX loop that caused some damage or a failsafe to trigger? My Mark IV also has this shared channel volume/FX loop level design and I've actually experienced something similar there when running a hot signal pedal through the FX loop with the channel volumes too high. The difference is there was noticeable distortion and crackling on the Mark IV but it did have a significant volume loss in the same way.

I will attempt trying the tube again today to see if it works running the channel volumes at different levels, but I'm curious, what channel volume levels is everyone running when they experience FX loop tone suck or inefficient volume? Is everyone aware that the manual states to keep the channel volumes between 9:00 – 12:00?

I believe what Mesa was trying to indicate when running the channel master above a specific setting, it will not do anything to the FX loop circuit. The FX loop level is on the high side to start with. Depending on channel used, the clean channel can easily push out +8dBu but you need to set the volume all the way up to get there.

There is nothing in the amp that I am aware of that will prevent the loop from working except for what you have in the loop. The send and return stages are always active and will be present in the signal path at all times. Turning on the FX loop only disconnects the internal short that couples the output of the send stage to the return input. The only amps I am aware of that have a hard bypass to the tube circuit for the FX loop would fall into the Rectifier line or the Mark V90. If it has a hard bypass mode, it will bypass the return gain stage completely. If the amp is working without using the FX feature, there is nothing wrong with the tube. If it was dropping out for some reason without having anything plugged into the FX loop jacks, then I would assume the tube is at fault.

I normally keep the gain and channel masters in parallel (meaning the lines on the knobs are parallel to each other as close as they can be). 1pm is typical where I set both. I have tried using different settings with the gain different than the channel volume and felt it was lacking in the desired sound I liked. Both channel volume and gain affect the output volume of the channel.

 

[MarkIVWump]

So I tried this again and I don't know if the bent pin had anything to do with it or if I wasn't seating the tubes properly but it worked fine. I'm fairly certain I seated the tubes properly on the first try though because I put 2 different alternate tubes in and they both caused the issue. I'm going to have my amp tech look at it in case there's some kind of loose solder joint on the tube socket or something.

Now that it's working, I think I detect a subtle improvement in both volume and tone particularly when the FX loop is on.

Is there anything that can be done with the reverb with a tube swap? I find it somewhat disappointing compared to a Roadster's reverb.

 

[bandit2013]

The Reverb circuit has a few op-amp buffered before it is sent to the tube driver circuit. The recovery stage which is also a tube circuit will then inject the output signal into the FX return gain stage. It actually runs in parallel to the FX loop. The tank is also a short 3 spring so it will not have the character of that used in the Roadster or even any of the Mark amps as they are the same tank (this may exclude the mini marks though). I found the reverb a bit lacking myself so I barely ever use it. I sort of got used to amps that have no reverb and required something in the FX loop to provide that effect.

That reverb circuit was intended for the 12AX7 tube so I would not venture far from that. I am not sure much can change with the reverb as it will still sound like a short and small tank regardless of what tube you try out.

 

[MarkIVWump]

The Reverb circuit has a few op-amp buffered before it is sent to the tube driver circuit. The recovery stage which is also a tube circuit will then inject the output signal into the FX return gain stage. It actually runs in parallel to the FX loop. The tank is also a short 3 spring so it will not have the character of that used in the Roadster or even any of the Mark amps as they are the same tank (this may exclude the mini marks though). I found the reverb a bit lacking myself so I barely ever use it. I sort of got used to amps that have no reverb and required something in the FX loop to provide that effect.

That reverb circuit was intended for the 12AX7 tube so I would not venture far from that. I am not sure much can change with the reverb as it will still sound like a short and small tank regardless of what tube you try out.

Based on this I was curious if I could swap in a long tank, but apparently the TC50 combo already has the same long tank that the Roadster has according to the Mesa parts shop. Only the TC heads have the short tank. So I guess my criticism of it is purely the way it's implemented in the circuit vs. other Mesa amps? It certainly has a different tone and timing to it compared to my Mark IV and Roadster which share the same tank. Would putting a 12AT7 in the Reverb stage potentially cause damage?

 

[bandit2013]

Interesting, did not know the combo has the long 2 spring tank. The RA100 head has that tank as well. Compared to the TC100 or TC50 I can hear a slight difference but not by much.

As for the 12AT7, you will not get the same level of effect. More or less due to the recovery stage than the driver stage. You could inquire with Mesa on the damage concern about using the 12AT7 in the reverb circuit. I do not have that answer.

You could try using a long plate JJ ECC803s tube in place of the Mesa 12AX7 (JJ ECC83s). It has a bit less gain than the standard tube but a different frequency response. Still, I doubt change of preamp tube will make much of a difference. Never tried a 12AT7 in the reverb of the TC series. I felt it was weak enough as is. Not sure it was meant to be that dramatic to start with. Unlike the California Tweed, most of the preamp tubes in that amp are used for the reverb circuit and it only has one tube used for a gain stage.