Diezel VH4S lost treble or highs...

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metalison

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A few months ago I played and fell in love with the Diezel VH4S (tested the amps on a Mesa Rectifier 212 combo, I think it has V30's). At that time I didn't have the money to take it with me but I found an occasion that is now stationed at our practicing area! :rock:

I tested the amplifier quick on location and the channels seem to work (could not really . Connected it with my own stuff, I felt there is something wrong. The sound is no where near what I played the first time. It sounds a bit muddier then I was expecting but where are the highs?? I have tried different guitars (esp, gibsons, fender, ibanez), stacks (V30's, G12K100, greenbacks), cables, positioning... Still no highs. (treble maxed, presence maxed, mid and bass 12 @ o'clock) :doh:

I think there is something wrong with my amp, but before sending is to a repair guy I was wondering if this could be a problem of worn or wrong tubes? Is it worth replacing the power tubes or it probably something else? I got electronics experience (not a lot with tubes) and with the well written guide from Diezel, replacing the tubes seem to be a piece of cake. :thumbsup:

Can anyone tell me what tubes should be present in this amp? (since its occasions, it might even contain the wrong tubes causing the issues) On the internet I find everything EL34, 6L6, KT88, 6550...

Cant wait to play this beast. :(
 
After reading a little further on the forums it seems that the VH4S leaves the factory with either EL34 of KT77 depending on the time they were build. Its probably a recommendation to replace the power tubes with JJ-KT77's when the time comes.
 
Current production leaves factory with KT77s, but earlier with EL34s and many years earlier with 6L6s. All do work so it is just a matter of personal taste + tube reliability.

If I understood correctly, you have obtained yourself an used amp. If that's the case, I would start by retubing (pre & power) the amp and if the highs are still lost I would contact Peter.

And congratulations for getting a wonderful amp!
 
Thanks i.ak!

I took my amp home for operation of the vocal cords. Will start with putting in new tubes for the aswell the pre as the power section.

Now just hope this will gets his highs back and he doesn't flatline :)
 
Got my new tubes yesterday and replaced the powertubes with KT77 tubes. Also changed pre amp tubes with fresh ones.

Only listened at low volume and the sound diffence is definitly noticable. Palmmutes sound a lot tighter and the deep controls seem to do what they should do again. Sounds so heavy it scares me! :scared:

Highs have changed but I feel them still lacking a lot. Will try and test this evening at higher volume, cant really do that at home. :D
 
didn't read the whole thread but- if you haven't had a chance, try it with another guitar and cab perhaps.. I've had an issue once with a volume pot going wrong loosing clarity/cut/trebles and it was an easy fix.. just to be 100% sure it's the head
 
Hi K-Mark,

thanks for your suggestion but I have already tried it with other cabs and the result was the same. Other cabinets make a day and night difference in sound but they all seem to lack highs on my amp. :confused:

I have come across an older topic that when I read it, I recon all things that were said. My amp is from 2005 (the amp mentioned is from 2004) and it also sounds a bit muddy, gain needs to be all the way up and presense it maxed out.
http://www.rig-talk.com/forum/viewtopic.php?f=14&t=93698

Anyone knows what the simple mod was to increase the presence? I dont see it anywhere in the other topic. :dunno:
 
Is the loss of treble/highs present on all channels or only with 3 & 4 and with high gain?
Do you have anything connected to loops or before the amp input (other than cable and guitar of course)?
Does the high and presence pots still have an impact to the tone if you turn them or are they "dead"?

In my opinion Diezels are a bit darker sounding amps (esp. older production) than some others, but definitely not too dark (at least with V30s) so I have a feeling there is still something wrong or our perception of muddines is different. No worries though, if there really is a problem with your amp Im sure Peter and rest of the team-Diezel will help you with that. You can find Peter's e-mail in the thread you linked above.
 
The loss in treble/highs is on channel 3 and 4 with high gain.
No loops or other input, guitar goes straight into the amp.
Seems the presence pots are working fine, presence is definitely added when turning em up.

Yesterday I tested the amp with 2 other guitarists and 1 of them being a VH4 owner. We all agreed that the amplifier was sounding like it is behind a very thick curtain. It sounds heavy, has enormous bass, but muddy, not defined and it definitely doesn't sound a bit aggressive due to missing highs. We changed to stack to a mesa rectifier 4x12cabinet, a orange 4x12 and a Marshall 4x12 cabinet. While sound differences noticeable it definitely lacks highs. It does sound heavy but definitely not metal...

I am going mad here, so taking this day off and do something totally different.
 
My amp is from 2006 and eventhough being darker than e.g. Mesa Mark V I had it definitely is not that dark as I understand from your description. Actually I think that my 2007 Herbert is darker than my 2006 VH4.

Might be good idea to send Peter an e-mail and possibly schedule an appointment to tech-surgery. I have a random thought that one or two capasitors and/or resistors inside your amp will need to be renewed. One source of this problem could be a failed powertube.
 
The company where I bought the amp suggested to send it back to them for surgery. Now all I can do is wait....
 
Got it back from tech surgery, 'something was wrong with the internal wireing'. We tested it last weekend and it still has the same sound. Too less highs, not aggrivese, muddy. I wonder if they tested the amp themselves. Even my Blackstar HT5 with a metalzone sounds a lot better... :(

Going to call mechanic tomorrow as I wonder what has changed. :gethim:

Starting to lose hope that I bought the right amp.... :cry:
 
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