Diezel Herbert humming and vibrating....??

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bananaladonpcp

bananaladonpcp

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I just got my first Diezel in the mail today! I'm really excited to have it and love the way it sounds!!! But there are two oddities going on and I'm wondering if someone can shed some light on them for me.

1. When I power on the amp and turn the standby off, the amp makes a humming sound and I can feel a vibration when I touch any of the eq knobs for channel 3 (I have tried turning every knob on the amp to zero and its still there and its the same on every channel) It doesnt matter if I have a guitar plugged in or if I have the volume on my guitar up or down. It sounds like a 60hz hum but what is the vibration from? It's not very loud but I am concerned about the vibration coming from the head.

2. The LED light for the V2 only sometimes works... And it never turns all the way on. Could it be related to the humming problem I'm having or did it just burn out and needs to be replaced?

If someone could shed some light and let me know if I should be worried or what I can do to fix this I would really appreciate it!!

Thank you :D
 
would you describe the vibrating as ''pleasant''? ;)


Sorry, cant help with the problem but i bet the others will show you the light
 
I would not describe it as pleasant lol. It feels like I'm feeling the electricity flowing through the amp. The herbert model I have has been worked on by Peter once before I think. I'm pretty sure that's his signature on the back along with Stephen's. It has 3 fuses one the back for the power tubes but you have to take the amp out to adjust the bias and the only way to adjust the bias is to remove the board thats connected to the effects loop and foot switch inputs. I thought that was alittle... odd.... And it also has a hum trimmer on it. I thought they only put them on the VH4's?
 
The herberts all do have a humtrimmer if im right but i didnt have any problem with mine, just wait for olaf, peter and the others, youlle get more help than you or the amp can handle
 
1. The humming needs to be adjusted via the hum trimmer inside. It's best to use ch3 to adjust humming as this channel hums the most. The amp needs to be taken out of it's shell, turned upside down, a cab attached and a guitar plugged in (guitar volume set to ZERO). Then turn the hum trimmer until humming is the lowest.

2. The LED is for the power tubes, not V2 (Vs are preamp tubes). If the light is ON it means the fuse has blown and you most likely need a tube change. Fuses blow for a reason. Since your amp was purchased used the tubes might be old and it is for sure a good idea to do a full tube change. I get lots of messages from folks who buy used Diezel amps and the tubes are faulty and old. Why not swap them and start fresh with optimal tone?

I would strongly recommend you taking the amp to a professional technician as there is high voltage lurking inside the amp (460V) !!!

You do NOT need to take out the circuit boards to bias a Herbert ! There are 3 different types of Heberts with 3 different ways of biasing. This should be done by a professional.

Kind regards,

Jens Kruse
 
Thank you for the answer Jens!!! And as is normal with any use amp I buy, I already ordered a full tube replacement for it. I was just worried about why it was vibrating and humming. I don't wanna hurt my new baby :D I'll let you know if I get the humming to go away!

As for the LED that isn't working. I should have been more specific. It's on the front of the amp and only comes on when I switch the master volume to channel 2. all my fuses are in good working order. But the LED doesn't fully come on. It only half way comes on. Just a bad LED? Here's a pic of the LED I'm talking about. I don't have any LED's on the back panel of the amp.

As for biasing the herbert... Sorry for being a noob lol. I will have to take a closer look at it when I adjust the hum trimmer.

Thank you again!!
 

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Hello Mr. Banana Lad (on PCP),

the LED should be replaced. They sometimes break. I've got replacements in stock. Please e-mail me if you need to get one.

Your Herbert has either external bias points (on back chassis, just behind power tubes), or internal bias terminals (newer Herberts), or the very old Herberts need to be biased at the power tube fuse holders which are mounted on the circuit board (right upper corner when amp is jacked up and control knobs facing you). I assume that the latter is what you have going on.

Jens

PS: Before you do anything with your amp, let the effect of PCP wear down first !
 
After I come down from the PCP I'll take a pic of where the Bias points are inside the amp. They are mounted on the Board. I happen to have a few Blue LED's laying around. I'll check the voltage on the ones in the herbert. If I dont have any that match up I'll shoot you an Email!! I also have one more question about some Pre-Amp tubes. I know Peter recommends the use of the Ruby 12AX7AC5 HG+ But how does he feel about the use of the new Rubys. The 12AX7AC7 HG+ ? The 12ax7ac7s are alot easier to find here in the USA as well...

Thank you for your time Jens!!! It is VERY much appreciated!
 
You mentioned that you have NO LEDs on the amp's back panel. If there are NO power tube LEDs in the back then you have an old Herbert that has NO bias terminals inside the amp and you need to use the fuse holders to bias.

You should buy the Diezel hand selected 12AX7AC5 HG+678 for V1, the high grade 12AX7AC5 HG+ for V2 and regular 12AX7AC5 HG for the other positions.

Jens
 
Heres some pics of the inside of the amp... One the first one... Those 3 pots underneath the effects loop board are the bias pots right? Btw the amp is from 2005.

Is that peters signature on the back along with Sefens?

Thanks guys! :D
 

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Yes the trimmers underneath the back board are the bias trimmer. However then can be accessed via the external bias points (3 black points) via your chassis (your last, bottom photo). This is the easiest to bias of all Herberts. Please don't remove the back board ;-)
You don't need to remove the amp from the shell at all to bias, just remove the back panel.

Jens
 
wow. I'm a total NOOB! :doh: :doh: :doh: Thank you Jens!!! The black rubber is meant to stay in place to protect me from touching the chassis while im biasing right? I'm sorry for being such a noob dude. The guy I bought it from told me it didn't have external biasing on it and I guess i just didn't think that it could be that lol. Thank you for your help!!!

Why would peter have signed this bad boy? Did it get sent back to diezel for something perhaps?
 
Hey,

just read this post and think I will also have to adjust my humtrimmer because there is some hum even on the clean channel, tubes are all ok.

Can someone make a picture of the humtrimmer-pot? would be great :thumbsup:
 
Hey DvE,

My hum trimmer pot is located about 3 to 4 inches behind the guitar input jack. Its white, looks like a standard bias adjustment pot, and it's labeled on the board as "Hum Trimmer" or something to that effect... I just put the amp back in the chassis or I would take a picture for you. But it's really easy to find.
 
In a few days I'm gonna have to take it back out to change a burnt out LED. If you haven't found it by then or want to wait till i take it out I can put up a picture for you.
 
Update on the Vibration that was happening inside the amp!!

Because I was told, by the person I bought my amp from, that it didn't have external biasing and, me being a total noob about Diezel products, believing him, I did not check the bias on my amp before I posted about the Vibration. I check the bias last night and it was..... waaaaaaay off. When I checked the level on tubes 1 and 6 my multi reader read 11.3mA. I knew that was wrong and thought there was something wrong with my meter, but decided to check tubes 2 and 5. Hooked it up and it read 32mA. Which would be correct if it was supposed to be biased for a single tube... The pot was turned all the way down. I adjusted it to the proper place 65mA and went back to check tubes 1 and 6, and it was reading a much better number this time. 60mA. After checking all 3 pairs 3 times and adjusting they were all dialed in correctly. I put the head back on my cabs and turned it on to see what it sounded like now (couldnt turn it up too much seeing how it was 3am) and the vibration inside the head was gone! I most definitely need a power conditioner but man does it sound fucking great! I can't wait to put the new tubes in there when they come and see what it really sounds like!!!!!!!
 
Alex, hope you took out the respective tube fuses when biasing each tube pair !

Cheers,

Jens
 
Yes I did Jens :D Thanks for your help! Hope to see the package you sent me in a few days! All the tubes should be here monday or tuesday :D Can't wait to get the new tubes in there!!!!!
 
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