Can you explain this?

Just2comment

New member
Here's the dilemma:
Rig: Diezel Herbert Head bought new 2010,
MK1, through a Diezel 4x4 Rear loaded cabinet.

2 months ago, develops background distortion in the clean channel. Sounds like a valve dying.
Emails Diezel direct and as usual gets no reply. Rings my guitar tech and he's says take it to this guy. My tech says trust him he's really good, knows he's stuff and re-valves all the amps in this part of the country. Takes it in, he strips it and finds one of the output stage valves dying. Replaces it, like for like and checks the other valves for signs of failure. Finds the preamp valves [Ruby tubes] noisy and feeding though into the output stage. [You could hear the hum / noise in the background with the guitar silenced]. After replacing them, he rings and says, do you want to replace the rest of the output stage valves, like for like? Given the extra cost, I agreed to go ahead.
Result: Herbert is absolutely silent, no background noise etc, perfect. Clean channel, perfect; Gain channels 2 and 3. Man what ever this guy did, it cooks sizzles and rocks, but it no longer sounds like a Diezel, its almost overcooked, if you know what I mean?
Some are going to be really happy with that, but the reason I bought Diezel inn the first place was the smoothness of the gain structure, articulate enough to hear every picked note, with no loss of clarity and even at dynamic speed. I loathe the sound of Marshall amps, and this now sounds like a Marshall on steroids. Can any diagnose the problem and tell me what the hell happened?
Thanks guys
 
So out sounds absolutely silent, no background noise, perfect, cooks, sizzles, rocks but doesn't sound like a Diezel?
I think these things can be dialed in close to a Marshall no? Never played one.
Are the settings and everything else back to the way it was before it left your crib?
So if the only thing that was changed was the tubes, then I'd experiment with different tubes. Different tubes can make a huge difference in a high gain, high quality amp like yours. What tubes are in there now exactly? Maybe the guitar tech guy will swap some out (like for like).
My .311 cents.
 
So out sounds absolutely silent, no background noise, perfect, cooks, sizzles, rocks but doesn't sound like a Diezel?
I think these things can be dialed in close to a Marshall no? Never played one.
Are the settings and everything else back to the way it was before it left your crib?
So if the only thing that was changed was the tubes, then I'd experiment with different tubes. Different tubes can make a huge difference in a high gain, high quality amp like yours. What tubes are in there now exactly? Maybe the guitar tech guy will swap some out (like for like).
My .311 cents.
Hi Dude, The Herbert is 180w RMS, more to give the clean channel more headroom. Mk2 has even more: story is band Korn use them extensively, so the Herbert was designed and built more or less for these guys. Two things I notice, is the pre re-valve settings, are now a good 2or 3 notches back, but the beast it has become really rasps in both the crunch and High gain channels and its really sounds sh*t
 
I think you’re used to a bias that is warmer (and harder) on the tubes. It will mellow it out and warm things up a bit.

HOWEVER, you’re better off rolling preamp tubes in V1 to tune the gain structure now. The amp always sounded like it is now, you’re just not used to it working as it should.

TLDR fuck with the V1 tube of gains 2 and 3 until you get the sound you like. If you want mellow maybe even try JJECC803 or EECC803S in V1. Stay away from sovtek. Be glad your guy could replace the failing powers tubes at all. Tubes that sound good are REALLY fucking hard to come by these days.
 
Any legitimate tech should have rebiased the amp with new tubes, but biased to what dissipation? Maximum 70% or colder to extend tube life? This usually will also affect sound.
 
And considering how many power tubes the Herbert has, it will change the sound more drastically than say a 50W.
Interesting I didn’t know that would be a factor.

When I rebiased my jet city 50 watt head it went from brittle and ice-picky at its very very cold stock bias (can’t remember what, like 10%, dissipation or something) to real woofy and mushy at 70%. I think I ended up somewhere in the middle.

My fryette 2/50/2 power amp I didn’t notice as drastic a difference by biasing hotter or colder (within reason). So I don’t know what other factors are at play.
 
I think you’re used to a bias that is warmer (and harder) on the tubes. It will mellow it out and warm things up a bit.

HOWEVER, you’re better off rolling preamp tubes in V1 to tune the gain structure now. The amp always sounded like it is now, you’re just not used to it working as it should.

TLDR fuck with the V1 tube of gains 2 and 3 until you get the sound you like. If you want mellow maybe even try JJECC803 or EECC803S in V1. Stay away from sovtek. Be glad your guy could replace the failing powers tubes at all. Tubes that sound good are REALLY fucking hard to come by these days.
Hey, some great advice here, I'm already learning a lot - keep it up my friend & thanks
 
6 x Ruby Tubes [12AX7AC] and 6 X KT77-JJ
Is this what is in there now?

I'm not a fan of those Ruby tubes. Like @glpg80 said, I would swap around some of 12AX7s in V1 and V2 (first position and second) to see how it changes your tone. Without getting into NOS (New Old Stock) tubes, I personally like JJ preamp tubes although there is plenty of hate on these too. But get a JJ, a Tung Sol and maybe a NOS preamp tube and swap it around and take notes as you go. Trust me, it is easy to forget what was what so document as you go so your time is valuable. Also try something different in the last, Phase Inverter (PI), stage which I am assuming is V6. I don't have a Diezel BTW. I have heard tons of good things about the Sovtek LPS 12ax7 for this slot but not tried it myself. I do have a JAN Phillips 5751 (compatible with 12ax7) in the PI of one of my amps and it is awesome there.

Good luck.
 
Sounds like something simple like tubes or bias. As my amp tech told me, sometimes amps sound their best right before the amp self destructs. Maybe those tubes were falling, and you liked the sound of the tubes?:dunno:
 
I Sent My Mesa To The Factory Once?
They Called Me And Asked Me If I Wanted To Sell It.
But Did Clean Up The Amp, New Tubes And Recaped
A Few Things. It Was Just A Bit "Cleaner" Sounding
After I Got It Back, It Needed Some Work And That
Need Shaped The Sound A Bit Is What I Am Saying.

The Way To Document The Amp Before Being Serviced
Is Pretty Hard To Do Really. Because The Amp I Had
Was 20 Something Years Old? it Needed Work.

I Didn't Know How To Document The Internals Of The
Amp And Ask Them To Keep The Values of Anything
Replaced At The Same Measurements.
Had I Known? I Would Not Have Needed It Serviced.
Sounds Like A Few Things Needed To Be Replaced
On Your Amp, And These Components Had Worn
Shaping The Sound?

The Odds Are ................

And I Just Looked This Over?
This Is Not Fun Looking To Do.
I Just Started To Understand
How Serving Sometimes Can
Change The Sound Of The Amp.

https://www.diezelamplification.com/manuals/service/service-manual_V1-1.pdf
Thanks, Yeh, its hard to document what it sounds like. One thing though? Do you know if the valves or tubes need a couple of hours running in before things settle down? The reason why I say this is, because all week I've been going to ring the Tech and ask him to back off the gain in the amp with a softer bias [ Yes got the service manual too], but thing is, its beginning to sound ever so slightly softer, still power like on steroids, but just sweeter somehow? Am I talking crap here or what?
 
6 x Ruby Tubes [12AX7AC] and 6 X KT77-JJ
Funny, I gave a guy on another forum, some Ruby 6L6 power tubes and some Rudy 12ax7 tubes.
Poor guy, he was going thru some bad ordeals in life .

Those Ruby tubes, didn't suit my gear too well, but he found them to be perfect for his needs.
 
Funny, I gave a guy on another forum, some Ruby 6L6 power tubes and some Rudy 12ax7 tubes.
Poor guy, he was going thru some bad ordeals in life .

Those Ruby tubes, didn't suit my gear too well, but he found them to be perfect for his needs.
Is it possible you can describe how the ruby tubes sounded? Was there a sort of fizz in the gain? Thanks
 
Is it possible you can describe how the ruby tubes sounded? Was there a sort of fizz in the gain? Thanks
For me, it didn't blend to well with the caps of my amp and the rest of my gear. It was too grainy.
The guy I gave the tubes to, was happy as can be , those tubes were everything he was looking for.
 
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