TA-30 treble trouble

[b mckee]

I was searching for a versatile amp that brings strong Vox tones and a secondary Marshall vibe, and picked up a TA-30 2x12 a couple months ago. Love the options but really struggling with the amount of treble in this beast. Even had a fellow gear nerd tell me to lower the treble during soundcheck a couple weeks ago. I'm playing standard guitars through it...a LP and a Tele and playing classic rock tones. Two questions:

1. I'm running the treble all the way down near 7:00 (on both channels), with the cut almost all the way up (4:00) on the Vox channel. Anything more than 7:00 is ear-piercing. Anything lower on the treble brings too many mids. Similarly on the drive channel, I've got the trele down near 7:00 (barely on). How do I fix this? Is a mod necessary?? Do I need to throw an EQ pedal in the fx loop??
2. Why would Mesa even make the tone range so narrowly useable in an otherwise incredible amp like this?

Was excited to get my first Mesa but now leaning towards buyer's remorse. I've thought about swapping in alnico speakers but I don't want to sink another $600 into a $1400 investment that should already sound amazing.

Please help!

 

[bgh]

Which side of the amp do you find to be the issue? Using the Vox side in cut mode can ease the treble saturation. On the other side, I have not had a treble issue per se. On both sides, I set the treble about half-way.

And, dumb question, but, when you say 7:00, are you facing the amp, or standing behind the amp?

I have not had an issue with mids disappearing. On the Marshall side, the middle and bottom positions of the 3-way switch are "Marshally." Of the two, the bottom is a bit darker than the middle position. Other than that, they are not a lot different. Does playing on the bottom position mitigate the loss of mids any?

 

[bandit2013]

Since it is a used amp, before you go chasing the speaker rabbit hole, I would first start with preamp and power tube replacements. They do not last forever, and some people often forget that fact. Refresh that amp with new tubes and then decide what to do next.

I am not all that familiar with the TA series so I cannot comment on the characteristics of the EL84 tubes getting close to their end of life. The preamp tubes also matter when it comes to tone. They generally run much longer than the EL84 in terms of usable life but the wear out too. Power tubes wear out quicker due to the amount of current on the plates and thermal changes to the materials may out-gas some impurities in the metal. The getter flash is there to absorb those gases to maintain tube vacuum. Mostly it is the getter flash absorption abilities as well as the cathode electron emissions. Either of them will lose their effectiveness over time. Tone changes in the power tubes such as loss of bass is a clear sign the tubes need to be replaced. Similar could be said about the preamp tubes but will take much longer for them to show signs of wear.

Based on a quick review of the tube task chart in the online manual of the TA-30, I assume that V3 is a dc-coupled cathode follower circuit as it is called out as the tone stack driver. If this assumption is correct, V3 would be the first preamp tube I would change as that will get the most abuse from the circuit (typically the root cause for tone loss with the Dual Rectifier amps). It id not appear that there were any other cathode follower circuits based on the tube task chart. Since there are no tube triodes identified as the FX send driver, I would assume that is done by the same method used by the Electra Dyne. TL072 op-amps seemed to be the designer's choice for that purpose. I was looking at the specifications of that device, very interesting. It uses all FETS and has an interesting Class A/B control used on the FET driven push-pull output circuit. These op-amps were widely used in the Electra Dyne, there are a few of them in the RA-100 for the clean channel and reverb circuit but that is also fully tube driven. They are also used in the TC-100 and TC50.

If the TA is spectrum of sound is anything like the RA, I do dial out the treble as the midrange control covers most of the top end frequency. Depends on the desired effect, sometimes I dial it all the way out or may set it too noon on the gain channels. The clean channel is different, more of a Fender circuit than a Brit so it is abundant in the low end, I have to dial that down and boost the treble to compensate.

Just note that the TA series is quite different than the RA series. I should get a TA-30, it sounds like an interesting amp to add to my collection. First time I heard one was at GC, someone came in to sell a 112 combo and the person who checked it out pushed it to the max, it sounded great.
Come to think of it, also need the ED too. I am surprised I do not have one yet.

 

[bandit2013]

Ah, I see the dilemma. I was unaware the TA does not have a midrange control. Really? I would assume that the video would be the norm for the TA-30 sound.

 

[b mckee]

Which side of the amp do you find to be the issue? Using the Vox side in cut mode can ease the treble saturation. On the other side, I have not had a treble issue per se. On both sides, I set the treble about half-way.

And, dumb question, but, when you say 7:00, are you facing the amp, or standing behind the amp?

I have not had an issue with mids disappearing. On the Marshall side, the middle and bottom positions of the 3-way switch are "Marshally." Of the two, the bottom is a bit darker than the middle position. Other than that, they are not a lot different. Does playing on the bottom position mitigate the loss of mids any?

Thanks for the reply! Both channels are overly bright. When I say 7:00, I mean the treble is almost completely off. The mids aren't going away, they become overly prominent when the treble is too low, since it's a fixed-mid eq circuit.

 

[b mckee]

Since it is a used amp, before you go chasing the speaker rabbit hole, I would first start with preamp and power tube replacements. They do not last forever, and some people often forget that fact. Refresh that amp with new tubes and then decide what to do next.

I am not all that familiar with the TA series so I cannot comment on the characteristics of the EL84 tubes getting close to their end of life. The preamp tubes also matter when it comes to tone. They generally run much longer than the EL84 in terms of usable life but the wear out too. Power tubes wear out quicker due to the amount of current on the plates and thermal changes to the materials may out-gas some impurities in the metal. The getter flash is there to absorb those gases to maintain tube vacuum. Mostly it is the getter flash absorption abilities as well as the cathode electron emissions. Either of them will lose their effectiveness over time. Tone changes in the power tubes such as loss of bass is a clear sign the tubes need to be replaced. Similar could be said about the preamp tubes but will take much longer for them to show signs of wear.

Based on a quick review of the tube task chart in the online manual of the TA-30, I assume that V3 is a dc-coupled cathode follower circuit as it is called out as the tone stack driver. If this assumption is correct, V3 would be the first preamp tube I would change as that will get the most abuse from the circuit (typically the root cause for tone loss with the Dual Rectifier amps). It id not appear that there were any other cathode follower circuits based on the tube task chart. Since there are no tube triodes identified as the FX send driver, I would assume that is done by the same method used by the Electra Dyne. TL072 op-amps seemed to be the designer's choice for that purpose. I was looking at the specifications of that device, very interesting. It uses all FETS and has an interesting Class A/B control used on the FET driven push-pull output circuit. These op-amps were widely used in the Electra Dyne, there are a few of them in the RA-100 for the clean channel and reverb circuit but that is also fully tube driven. They are also used in the TC-100 and TC50.

If the TA is spectrum of sound is anything like the RA, I do dial out the treble as the midrange control covers most of the top end frequency. Depends on the desired effect, sometimes I dial it all the way out or may set it too noon on the gain channels. The clean channel is different, more of a Fender circuit than a Brit so it is abundant in the low end, I have to dial that down and boost the treble to compensate.

Just note that the TA series is quite different than the RA series. I should get a TA-30, it sounds like an interesting amp to add to my collection. First time I heard one was at GC, someone came in to sell a 112 combo and the person who checked it out pushed it to the max, it sounded great.
Come to think of it, also need the ED too. I am surprised I do not have one yet.

Thanks for the detailed reply! Hadn't considered the tubes to be an issue. Maybe I'll take this in to a tech and have them run through it. I suspect the overall eq range for this amp is what it is, which is disappointing considering that Mesas are known for their eq tweakability.

 

[bandit2013]

It helps if you have familiarity with the amp when it is new and has fresh tubes. I posted the video as I assume that is the norm of how it should sound.

Not familiar with the TA amps. I have tried to find a schematic of this amp thinking it was similar to the Royal Atlantic but had no idea it was that different. No luck with the schematic either. Schematics are essential when the amp becomes discontinued. I am sure Mesa keeps an archive of their work as to the certified techs.

I hope you get some resolve on it. If it is that bright, there is the option of using an EQ pedal in the loop if fresh tubes do not correct the issue. Sorry I am of no help on this. Hopefully some TA users will chime in with some assistance. The RA users in the forum are limited. Once was but no more a popular topic. It is either Dual rectifier of the vintage offering or Mark V.

 

[bgh]

Thanks for the reply! Both channels are overly bright. When I say 7:00, I mean the treble is almost completely off. The mids aren't going away, they become overly prominent when the treble is too low, since it's a fixed-mid eq circuit.

I don't know enough about amp internals to tell you much. I know on mine, the treble is not nearly that aggressive.

When I have had questions about my Mesas, I called them directly. Most of the time, they have been able to answer my questions. It may be an option for you.

 

[b mckee]

Ah, I see the dilemma. I was unaware the TA does not have a midrange control. Really? I would assume that the video would be the norm for the TA-30 sound.

Yeah, it's a fixed mid eq section, like a Vox.

 

[b mckee]

I don't know enough about amp internals to tell you much. I know on mine, the treble is not nearly that aggressive.

When I have had questions about my Mesas, I called them directly. Most of the time, they have been able to answer my questions. It may be an option for you.

Thanks bgh, maybe I'll call them directly & see what they have to say. It is definitely a noticeably bright piercing (and limited value) eq.

 

[bandit2013]

Calling in to customer service will route you to Gibson in Nashville. I would recommend the email route first.

 

[Doug Doppler]

I have the little brother - TA-15 which I bought because of the Vox-like qualities. Mine is bright and chimey, but not overly so. Like the Vox amps I own, it can get too bright at more extreme treble settings. It is POSSIBLE that if you bought it used at say Guitar Center, a classic move is to swap the stock speakers for whatever. Could be the speakers are out of phase and that is why you have no low end. LOVE my amp, BTW