Need advice for my poor VH4

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opiateofthemasses

Member
I bought my 2003-ish VH4 used YEARS ago. Sometime around 2007-2008 I think. I had owned a Herbert before then, and it was awesome, but for my needs a VH4 was what I wanted. I distinctly remember getting it and being a bit let down initially by what I heard. It sounded good, but not in the way I thought it would. It seemed to lack gain, punch, and was darker than I expected. regardless I loved it, and gigged the hell out of it...but I had no other VH4 to compare it too in person. Well recently I got a capture box, and made a direct capture through a load box. I then compared it too a fellow owner who did the exact same thing with the exact same settings. My tubes are not new, but not burnt out either.

This was the result. I know this isn't a direct a/b comparison because there's a few years difference between the amps, but I don't think it should be THIS drastic of a difference.

The first clip is my capture, the second is his. Gain is at 50% on both. Channel 3, mids full, bass- 3 o'clock, treble - 3:30. Presence and deep same as bass and treble.



If this is ringing any alarm bells so to speak for anyone who knows better I would very much appreciate some advice on steps to take next. I live in central IL, so not exactly close to any known Diezel repair shops lol. If I DO need to send it somewhere I will of course, it just makes me nervous because even if its broken, this amp is irreplaceable. Thanks!
 
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Do you know what year the fellow owner's VH4 is and how the tubes compare to your's? If I'm not mistaken, Diezel revised the amp's circuitry at some point (2012...?) to make it brighter. I will have to defer to the experts for the exact timeline.
 
skelt101 said:
Do you know what year the fellow owner's VH4 is and how the tubes compare to your's? If I'm not mistaken, Diezel revised the amp's circuitry at some point (2012...?) to make it brighter. I will have to defer to the experts for the exact timeline.
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Mines around a 2003, and his is a 98. As far as tubes I'm not completely sure, but this has been a known issue for me personally since I got mine, and I've got through a few different tube replacements and changes through the years just trying to figure out what the deal was.
 
skelt101 said:
Do you know if the bias has been adjusted on the Power Tubes?
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I'd have to check. All I know is what you heard is accurate to what mine has always sounded like, and just curious to know if that's what a 50% gain channel 3 VH4 is supposed to sound like, or if it's closer to his.
 
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opiateofthemasses said:
Mines around a 2003, and his is a 98. As far as tubes I'm not completely sure, but this has been a known issue for me personally since I got mine, and I've got through a few different tube replacements and changes through the years just trying to figure out what the deal was.
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I have owned the older version (which you have) and currently own a 2022 VH4. The updates and differences have been described as minimal, but not to my ears. The VH4 I own now is brighter, less compressed and seems to have a more gain. Overall, I would describe it's character as more aggressive. Additionally. channel 4 on the previous version was unusable as a rhythm tone. I love channel 4 on the current version for metal riffing. None of this may be relevant as you are comparing yours to a 98, which may also have been a different spec.
 
I wouldn't worry about it to be honest. Yours sounds good to my ears and just because the pots are in the same position, it doesn't mean the amps are actually set the same. Pots have stupid high tolerances. +/- 10% is nothing. Sometimes the values are quoted at +/- 20% or higher. I don't know what pots Diezel buy but the two VH4s in the clips could have some pots that are at opposite ends of the tolerance spectrum. I'm confident you could match the tones with a bit of knob twisting.
 
After listeNing to that clip, I would check to see if all your preamp tubes are exactly the same between the two amps….. I have two VH4’s….one has a 4004 Mullard in V1 and the other has an Engl VF in V1. Very different sounding…..
 
I hear the big difference in the two clips also. Don't quite know what the answer is to fix it, whether it's possibly functioning but tired Power tubes tubes, poorly functioning preamp tube or two, voicing of the amp compared to the current models, pot sweep ranges, bias setting..

I found a NFB change helped opened up the amp for my tastes, as it always felt a bit too chubby and spongy and that I couldn't dial out without cranking the treble and presence. This is at low reasonable volumes mind you, cranking it right up it has tones of top end available to dial back.
A nice V1 tube and 6L6's also helped a bunch for me. The EL34 sound wasn't doing it for me anymore.

I'm keen to see what the issue and fix is for you.
 
Most VH4’s I’ve heard sound more like the 2nd amp. So does my VH4S Stereo.
I’d get new tubes in there, preamp and poweramp.
Bias it correctly.
Check the filter caps.
I also did the Bright/more Presence mod on mine.
Love my VH4S.
 
jdel77 said:
Most VH4’s I’ve heard sound more like the 2nd amp. So does my VH4S Stereo.
I’d get new tubes in there, preamp and poweramp.
Bias it correctly.
Check the filter caps.
I also did the Bright/more Presence mod on mine.
Love my VH4S.
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I'm interested in the bright / presence mod...Was it complex? Thanks.
 
Yeah, it's easy as hell. I was sold when I saw how easily reversible it is. No messing around with the boards or anything fiddly.
 
Yep. I found it opened it up a bit and removed some of the 'congestion', to borrow a phrase, that I was hearing.

I just re-read your earlier posts, yours is a 2022? Mine is a 2010, so by the description of yours currently it could be already brighter and more open than mine was originally. I'm not sure now if the NFB mod would make as big a difference for yours as it did to mine. That said, its easy enough to try if you really want to see.

Cheers - Phil
 
Philhouse said:
Yep. I found it opened it up a bit and removed some of the 'congestion', to borrow a phrase, that I was hearing.

I just re-read your earlier posts, yours is a 2022? Mine is a 2010, so by the description of yours currently it could be already brighter and more open than mine was originally. I'm not sure now if the NFB mod would make as big a difference for yours as it did to mine. That said, its easy enough to try if you really want to see.

Cheers - Phil
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Appreciated, thank you. May give it a try.
 
angelspade said:
Appreciated, thank you. May give it a try.
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Totally worth it - easy mod to do and adds more available high end if you want it. Also makes the amp slightly less squishy feeling, giving a tighter and quicker attack.
I've grown up playing high headroom amps like 70's Oranges and Hiwatts, JMI AC30's, and have been using Boogie Marks and my Soldano SLO for years. I'm used to tight and quick amps with lots of control and precision, so this made the VH4 a better amp for me.
Having said that, if you want the squish and compression back, just up the gain a little bit.
The difference between not having the mod and having the mod isn't night and day, but it's there though. You could probably get pretty close using high wattage/power speakers, same kinda feel.
 
opiateofthemasses said:
I bought my 2003-ish VH4 used YEARS ago. Sometime around 2007-2008 I think. I had owned a Herbert before then, and it was awesome, but for my needs a VH4 was what I wanted. I distinctly remember getting it and being a bit let down initially by what I heard. It sounded good, but not in the way I thought it would. It seemed to lack gain, punch, and was darker than I expected. regardless I loved it, and gigged the hell out of it...but I had no other VH4 to compare it too in person. Well recently I got a capture box, and made a direct capture through a load box. I then compared it too a fellow owner who did the exact same thing with the exact same settings. My tubes are not new, but not burnt out either.

This was the result. I know this isn't a direct a/b comparison because there's a few years difference between the amps, but I don't think it should be THIS drastic of a difference.

The first clip is my capture, the second is his. Gain is at 50% on both. Channel 3, mids full, bass- 3 o'clock, treble - 3:30. Presence and deep same as bass and treble.



If this is ringing any alarm bells so to speak for anyone who knows better I would very much appreciate some advice on steps to take next. I live in central IL, so not exactly close to any known Diezel repair shops lol. If I DO need to send it somewhere I will of course, it just makes me nervous because even if its broken, this amp is irreplaceable. Thanks!
Click to expand...

Sounds like some old tubes to me. And the powertubes sound like they're biased too cold.

Get some new preamps in there - C9 across the board - that's right - good ol' Chinese/Shug 9th gen preamps, stick an LPS in the PI slot, and make sure your powertubes are biased correctly depending on what bottles you got in there.

Major stupid question - but DO YOU HAVE THE POWERTUBE TOGGLE SWITCH ON THE CHASSIS in the right position???? Ya, it's happened before...so, just axin'

Peace n Powerchords,
Mojo 🤘
 
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