VH-4 Channel 4 EXTREMELY noisy... preamp tube help?

Mizati20

Mizati20

New member
Hey fellas, I'll keep this short and sweet...recently picked up a VH-4...2012 model that is amazing...

Channel 4 is uncontrollably noisy... even with a Pro Rack G running in front of the amp and in the loop is can barely control the squealing and feedback, not to mention just the high gain "hiss" overall is exceptionally loud... for reference this is with the channel volume around 2 o'clock, and the master at maybe 9 o'clock... channel 3 also has a fair more hiss than other versions I have owned...

Please keep in mind I know this is a very high gain channel, and some hiss is to be expected, but I have owned 5 of these things, and have enough experience with these heads to know this is absolutely abnormal compared to the others I have owned...

I did a search on the forums on stock preamp tubes and found mixed results, I pulled the chassis and checked all the tubes and wrote down all the lettering on them, they are as follows..

(Assuming V1 is closest to the guitar input)
V1 : Ruby 7025SS/ 12AX7A

V2 - V7 are all the same : Ruby 12AX7AC5

Are these the stock preamp tubes?

Power tubes are JJ KT77's but I doubt those are the issue...

Any input and advice would be absolutely fantastic, thanks fellas!!! :thumbsup: :thumbsup:
 
I think those are all stock tubes.

Have you tried running the signal completely dry, ie with nothing in the loops & the FX send off?

These are almost always tube faults. A full re-tube is pretty costly, but it's a good idea to keep spares.

Can you pull some tubes out of your other amps to test?
 
JimmyBlind":zqzsvxi1 said:
I think those are all stock tubes.

Have you tried running the signal completely dry, ie with nothing in the loops & the FX send off?

These are almost always tube faults. A full re-tube is pretty costly, but it's a good idea to keep spares.

Can you pull some tubes out of your other amps to test?
Click to expand...

Ya brother I've plugged just straight into the amp, should have mentioned that... I'm pretty good with gear, but I have purposefully made myself stay away from tube swapping/speakers swapping... that sort of thing, because it's a whole can of worms I just don't want to get into because it will be a never-ending chase... as long as something is working I usually just don't mess with it ya know? But the result of that is I don't know much when it comes to preamp tubes and such, power tubes are a bit a of a different story...

Thanks for the help regardless, looks like i'll be ordering some preamp tubes probably...
 
For a quick check try swapping v2 out with v1. If that doesn't work put the original v1 back in and put the original v2 tube in v3 (putting orig v3 in v2) and check.. Another layman check is to take something like a butter knife and GENTLY tap each preamp tube's glass while the amp is running (make sure the input is plugged in too) to see if the tube is reacting like a microphone would.

Retube is the best bet, but that might get you running until you get tubes in.
 
Mizati20":3tt0r9xn said:
Hey fellas, I'll keep this short and sweet...recently picked up a VH-4...2012 model that is amazing...

Channel 4 is uncontrollably noisy... even with a Pro Rack G running in front of the amp and in the loop is can barely control the squealing and feedback, not to mention just the high gain "hiss" overall is exceptionally loud... for reference this is with the channel volume around 2 o'clock, and the master at maybe 9 o'clock... channel 3 also has a fair more hiss than other versions I have owned...

Please keep in mind I know this is a very high gain channel, and some hiss is to be expected, but I have owned 5 of these things, and have enough experience with these heads to know this is absolutely abnormal compared to the others I have owned...

I did a search on the forums on stock preamp tubes and found mixed results, I pulled the chassis and checked all the tubes and wrote down all the lettering on them, they are as follows..

(Assuming V1 is closest to the guitar input)
V1 : Ruby 7025SS/ 12AX7A

V2 - V7 are all the same : Ruby 12AX7AC5

Are these the stock preamp tubes?

Power tubes are JJ KT77's but I doubt those are the issue...

Any input and advice would be absolutely fantastic, thanks fellas!!! :thumbsup: :thumbsup:
Click to expand...

Hello, my friend :)

I had this issue a few months back and I am more than certain it is a microphonic preamp tube. In my case it was V2 and V3 (if I remember correctly) maybe one other. If it is just channel 4 then it is probably V2.

And yes, V1 is closest to guitar input. The stock tubes are as follows:

V1- Ruby 12AX7 HG+ 678 (Diezel selected)
V2- Ruby 12AX7 HG+
V3-V7 - Ruby 12AX7 HG

However, there are alternatives that Peter also says are good. I will try to find the PDF file for you :)

Edit: here is the latest PDF that I could find. Also, if you get your tubes through Laura at Valvequeen, she will know exactly what to get for your VH4 ;) (she has a D-Moll) That is where I get my tubes.
 

Attachments

  • Diezel Stock Tubes-4.pdf
    1.3 MB · Views: 337
Wow thanks for all the help fellas... the tubes aren't microphonic or anything like that, tapping on any of them other than V1 results in zero noise... V1 you can hear the tapping a bit, but I have found that to be the case on every tube amp I have owned... I guess I have some preamp tubes to order... thanks guys!
 
Ever solve that problem? Mine is exactly the same - channel 4 super noisy - did all the things you did and no help - short of replace all of the preamp tubes. Did a retube help a bit?
 
I had a blue face VH4 that was noisy no matter what tubes I put in it. I contacted Diezel for help and was sent to their "repair center" 30 miles from my house in a BAD section of town at an electronics place that fixed DVD players and TVs...they had the amp 3 weeks and couldn't find it. Took it to a different tech who had it for a week and couldn't find it, took it to my own tech (who wasn't factory authorized, but who is EXTREMELY knowledgeable) and he couldn't find it, so I finally got fed up and told them I wanted a Herbert instead and they agreed to a swap. That solved it.
 
Which was the name of the repair center we recommend ?
I´m every time here to help the techs. To find out or repair
a noisy preamp section should be not a big deal. Just send
me an email.
 
I talked via phone to a Peter at Diezel, the amp in question was bought at the Axe Palace in Walpole Ma before I knew of this forum. You guys sent me to some electronic repair place in Lawrence Ma (or Lowell, I can't remember), but it was a BAD section of town for sure, they mostly fixed televisions and DVD players, etc...They couldn't fix it...this was AFTER I re-tubed the preamp section at home with tubes known good right out of another amp. 3 techs looked at that blue face and couldn't fix it...it sounded like fluorescent light noise or a burglar alarm noise (it wasn't, neither were running in the area the amp was used in, at least at my house). I'm happy with the outcome anyway, not trying to throw anyone under the bus here...
 
Picking up all new preamp tubes today to see what happens.

Peter - is there a tech in the Phoenix area you feel does good work on Diezel's? I suggested one a while back (Hunt Amplification), and will go to him in the future, if there's no one else you might know about.
 
All preamp tubes replaced with brand new ones. Channel four still substantially louder than three. Unplug guitar, absolutely dead quiet - that's probably how it should work. Switched guitars, cords, with/without fx. Even with gain turned down to 8 o'clock, still much louder hum than channel three at any setting, including gain at 3 o'clock ish. All amp high gain channels are somewhat loud, but this is almost to the point of distraction - kind of a pisser because the sound of the channel - ooh baby, ignoring the hum. Other users, herr Peter - fixable or not - or maybe I'm just asking for something not possible in super high gain amps? Suggestions? Channel three can run up in the area of four with the gain cranked, but it seems a waste to have an entire channel just sitting there...might as well have a three channel amp. Pretty sure it's a 2005 model. Seems a reach, but could power tubes make a diff?
 
MikeDV":boz0yqkq said:
All preamp tubes replaced with brand new ones. Channel four still substantially louder than three. Unplug guitar, absolutely dead quiet - that's probably how it should work. Switched guitars, cords, with/without fx. Even with gain turned down to 8 o'clock, still much louder hum than channel three at any setting, including gain at 3 o'clock ish. All amp high gain channels are somewhat loud, but this is almost to the point of distraction - kind of a pisser because the sound of the channel - ooh baby, ignoring the hum. Other users, herr Peter - fixable or not - or maybe I'm just asking for something not possible in super high gain amps? Suggestions? Channel three can run up in the area of four with the gain cranked, but it seems a waste to have an entire channel just sitting there...might as well have a three channel amp. Pretty sure it's a 2005 model. Seems a reach, but could power tubes make a diff?
Click to expand...

Again, please send me an email:

peterdiezel (at) diezelamplification (dot) com
 
After exchanging a couple of emails directly with Peter, I took the amp to my tech here in Phoenix. Peter had mentioned a possible "hum trimmer" as a potential problem. The tech opened it up, looked at that thing (like a little volume pot on the circuit board), turned it with a tiny screwdriver and now it's the quietest high-gainer I've ever had.

Too bad those of you who got rid of them because of this problem weren't lucky enough to find the problem so quickly/easily/cheaply. Now with new preamp tubes, and no hum/buzz, it's positively a fire-breathing dragon ready to wipe out any comers. Bring it on, Joeffrey! (game of thrones reference, for you non-nerds out there).
 
The hum trimmer adjustment was tried in my amp to no avail, so I'm not sorry I ditched it for a Herbert.
 
I'll also mention that this was a brand new amp with a warranty and there was a LOT of stuff going on...I gave you guys the watered down version of it...one of the ideas I was approached with was to send the amp to a tech in LA (I'm east coast) that ended up being sued by Diezel or something like that, so I was glad I didn't go down that road...there were also disputes with the dealer that sold it to me and all kinds of other stuff that went down, which I thought were out of place on a product that you pay 4000 dollars for.
 
Hello Papa!

I was curious as to why the hum trimmer was switched out with a couple of resistors after I had my amp sent to Jens when he was working with Diezel?

Thanks ;)
-Cam
 
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