bad sounding twin reverb-amp wizards help!

Erich Meisberger · Post by **Erich Meisberger** » 14 Mar 2013 7:12 am

Hello all,
I have a 1979 twin reverb that was hand wired to blackface specs about two years ago. The problem I am having with the amp is the high harmonic overtones it emphasizes. These overtones are, I believe, inherent to the guitar as I can hear them when playing through my blues deluxe and ever so faintly through the Vox headphone amp. They are probably even a desirable feature of the tone. The issue is that through the twin they scream at you and literally overpower the fundamental note.
I don't think it is a filter cap/ghost note issue as they were all replaced in the re-wiring and I can perceive the overtones through other amps.
A different speaker cab was tried but the overtones were still present. The speakers in the amp have the serial number 12388 67-8540.
The amp is going to the tech next week. He has some ideas such as changing the values of some caps, or possibly some sort of reverse presence control.
Any info or suggestions I could pass on to my tech would be greatly appreciated.
I know that deep down, underneath the highs, this is a great sounding amp. Currently it is not too easy on the ears.
Thanks for reading,
Erich

Lane Gray · Post by **Lane Gray** » 14 Mar 2013 7:45 am

Why not experiment with a tone knob on the guitar or a little box on the leg, bleeding some highs away before the amp sees it? You said it's too bright in anything you run through.

Tim Marcus · Post by **Tim Marcus** » 14 Mar 2013 7:49 am

are you taking it to Bill Caruth? Because you should

George Seymour · Post by **George Seymour** » 14 Mar 2013 9:14 am

Or Dan Lurie @ FYD Amps
He's in South Burlington

Erich Meisberger · Post by **Erich Meisberger** » 14 Mar 2013 9:35 am

Hey guys,
Thanks for your replies.
Bill Caruth did the rewire and its going to him. He has been a super guy to work with and has already gone above and beyond.
I once had a friend run it through an eq and he said he was unable to get the highs out of it. That being said, I'm going to jump on the next little izzy that comes up or possibly the Sarno unit.
Specifically, the sound is most pronounced at the tenth fret strings 1,2 or 3,4 no pedals and fret five strings 4,5 with pedals. There is also a distinct sleigh bells-like overtone at fret three strings 10,8,6 with pedals.
Overall it just sounds like sleigh bells are ringing with every chord I play. I even think it causes excessive ringing in the ears which I am experiencing at this very moment.
Thanks again,
Erich

Tim Marcus · Post by **Tim Marcus** » 14 Mar 2013 10:06 am

Erich Meisberger wrote: There is also a distinct sleigh bells-like overtone at fret three strings 10,8,6 with pedals.
Overall it just sounds like sleigh bells are ringing with every chord I play. I even think it causes excessive ringing in the ears which I am experiencing at this very moment.

output tubes rattling - guaranteed

its the worst part of new production tubes - I have to go through quite a few before I find octal output tubes that do not have this problem.

might also be a preamp tube but my money would be on one of your 6L6s. This is why I use Ruby tubes - with their 6 month warranty, I can keep sending them back until I get a quad that does not do the sleigh bell rattle.

Unfortunately no vibration dampener will stop it.

Try to get the noise to happen using a tone generator and then grab tubes on the back of the amp - my guess is that you will find at least one that is rattling.

Erich Meisberger · Post by **Erich Meisberger** » 14 Mar 2013 10:35 am

Thanks Tim,
It's good to know someone else knows what I mean about the sleigh bells.
I'll pass this on to Bill and we'll try what you suggest.
Thanks,
Erich

Tim Marcus · Post by **Tim Marcus** » 14 Mar 2013 10:47 am

no problem! Hopefully I am right and replacing a tube solves the problem

I was thinking a bit more, and I have heard a preamp tube do this before as well. Sometimes there is a node on the chassis that vibrates more than other places. Make sure you check them all

Richard Sinkler · Post by **Richard Sinkler** » 14 Mar 2013 12:24 pm

Just a curiosity question here. You say it could be the output tubes, or maybe a preamp tube. That would explain the problem on that one amp, but he said he tried other amps, which granted, could have the same issues, but he said he could hear it through his Vox headphone amp, which if it what I am thinking it is, has no tubes at all in it. Wouldn't this tend to make you think it was something before the amp?

I am no amp expert, but I would think if the same symptoms showed up in multiple amps, it was something that was constant in every setup.

Tim Marcus · Post by **Tim Marcus** » 14 Mar 2013 12:27 pm

when I hear someone say "sliegh bells" my mind automatically goes to tube rattle

They are probably even a desirable feature of the tone. The issue is that through the twin they scream at you and literally overpower the fundamental note.

sounds like the other amps were not really giving him a headache like the Twin was

Richard Sinkler · Post by **Richard Sinkler** » 14 Mar 2013 12:31 pm

These overtones are, I believe, inherent to the guitar as I can hear them when playing through my blues deluxe and ever so faintly through the Vox headphone amp.

I was just wondering based on his initial statements. Sounds like an issue with more than one amp.

Has he tried a different guitar through the same setup?

Stephen Cowell · Post by **Stephen Cowell** » 14 Mar 2013 12:41 pm

My guess is that you've got parasitic oscillations being triggered by your high-frequency input. 'Blackfacing' a Twin is not necessarily a good thing... the factory modifications were done for a reason. Your amp is not an 85watt Twin, it's at least a 100w Twin... and those extra watts take a toll on layout, etc. The amp was wired with plastic multi-stranded wire instead of the old solid-core cloth wire... the solid wire stays where you put it, and in an amp like the TR the way the wires lay can mean the difference between success or failure.

You have to look at the output via an oscilloscope... if the trace has creamy, filled-in parts during the harshness then you have parasitics. And if your tech can't make it work right you might just need a new tech.

Erich Meisberger · Post by **Erich Meisberger** » 14 Mar 2013 1:21 pm

Thanks for your thoughts guys. This is all good insight.
Just to answer Richard's question, I can hear what I think are the same harmonics through the different amps but they are only offensive through the twin. They are almost imperceptible through the Vox and subtle through the blues deluxe. It is possible that the twin has two problems; sleighbell rattle and emphasizes the highs too much. Or is it that the sleighbell rattle syndrome makes the natural overtones that the guitar produces sound bad instead of musical?
I'm off to band practice with my blues deluxe.
Thanks again,
Erich

Richard Sinkler · Post by **Richard Sinkler** » 14 Mar 2013 2:03 pm

Thanks for the clarification Erich.

Ivan Funk · Post by **Ivan Funk** » 14 Mar 2013 3:51 pm

I would plug a strat into it, crank it up, and see if those bells are pleasant or unpleasant.
If it sounds sweet then that's the blackface sound (that's not so good for steel)

Donny Hinson · Post by **Donny Hinson** » 20 Mar 2013 2:40 pm

Tell your tech to check the negative feedback resistor value. As I recall, it's 820 ohms in a B/F. If the value is correct, you could try changing it to 680 ohms, or 560 ohms. (This will greatly reduce the higher harmonics the amp produces.)

I also sorta agree on the suitability of a B/F for pedal steel. They do break up pretty fast, which is helpful for straight guitar players, but detrimental for most pedal steel work.

Bob Hoffnar · Post by **Bob Hoffnar** » 20 Mar 2013 9:14 pm

I wold try tuning off the reverb. Most every time if had a whistling tube issue in my old twin it was in the reverb section.

Erich Meisberger · Post by **Erich Meisberger** » 21 Mar 2013 7:10 am

Hello all,
Well, a snowstorm put off the tech visit for a week. That's why no updates yet.
Donny, thanks for the suggestion. We will try that.
Bob, Believe it or not, the noise is easier to hear with the reverb off.

I really think this amp has two issues. The first and worse being the sleighbell sound (which I have only heard with the twin) and the second being the painful highs.

The more I play through the blues deluxe the more I realize that it also produces highs which are inappropriate for steel. I think I need to find a rig which sounds like the Vox (bass version) headphone amp.

I'll let you know how it goes.
Thanks,
Erich

George Seymour · Post by **George Seymour** » 21 Mar 2013 9:49 am

Hey Eric
I live in Waterbury
You should stop down
I've got some good amp configurations including a newly aquired Fender Playing in Morrisville Friday and Derby Saturday night if you want to hear my set up live for some ideas

Erich Meisberger · Post by **Erich Meisberger** » 21 Mar 2013 10:12 am

Hi George,
I'll give you a call.
Erich

George Seymour · Post by **George Seymour** » 21 Mar 2013 10:30 am

I've known Billy for many years!

George Seymour · Post by **George Seymour** » 22 Mar 2013 2:19 am

Erich,
Had a nice talk with Bill on the way to practice.
I'm bringing my amp to his shop and have him look it over next Saturday, also see about the mod that was done to it. It may be just the ticket for your amp.
Talk later,
George