My VH4 - not sure it is healthy - thoughts???

[EOengineer]

*cough* sell the VH4 buy a Mark VII *cough*

 

[Eagle]

*cough* sell the VH4 buy a Mark VII *cough*

Massive downgrade .

 

[EOengineer]

Massive downgrade .

 

[Orvillain]

So my tech has the amp. At first glance, there doesn't seem to be anything circuitry-wise that is wrong. There's some interesting stuff about this amp.

- The service manual implies that some of the power filter caps are mounted to the PCB. Not so on my amp. They're mounted to the chasis, and then connected to the various points required.
- He reckons the filter caps are okay. The tops of a few of them are bulging, but there's no fluid leaking from them. He's going to test them.
- There's a power supply resistor that the service manual says if it is a 2.2k rated one, replace it for a 4.7k rated one. Mine is rated for 3.3k, so ... that's odd. He's gonna replace it for the 4.7k one.
- The service manual says that the NFB should be connected to the 8ohm tap, but mine is connected to the 4ohm one. He's gonna switch that over.
- All of the screen grid resistors check out okay.
- There's no uneven discolouration on the KT77 valves, but he's going to test them. Also I'm going to purchase a matched quad of 6L6's or EL34's to try in the amp.
- He's gonna test the preamp valves too.

There's really nothing awry with the amp at first glance.

 

[deadpool_25]

Despite giving zero shits about Tool, Adam Jones or the guitar tones he uses.

 

[deadpool_25]

as a Tool and Adam Jones fanboi since I was 16 years old

 

[laxu]

So my tech has the amp. At first glance, there doesn't seem to be anything circuitry-wise that is wrong. There's some interesting stuff about this amp.

- The service manual implies that some of the power filter caps are mounted to the PCB. Not so on my amp. They're mounted to the chasis, and then connected to the various points required.
- He reckons the filter caps are okay. The tops of a few of them are bulging, but there's no fluid leaking from them. He's going to test them.
- There's a power supply resistor that the service manual says if it is a 2.2k rated one, replace it for a 4.7k rated one. Mine is rated for 3.3k, so ... that's odd. He's gonna replace it for the 4.7k one.
- The service manual says that the NFB should be connected to the 8ohm tap, but mine is connected to the 4ohm one. He's gonna switch that over.
- All of the screen grid resistors check out okay.
- There's no uneven discolouration on the KT77 valves, but he's going to test them. Also I'm going to purchase a matched quad of 6L6's or EL34's to try in the amp.
- He's gonna test the preamp valves too.

There's really nothing awry with the amp at first glance.

Sounds like a lot of stuff that might have been tweaked a bit on the circuit over time?

 

[MirrorProfiles]

If they’re bulging they’re probably dried out and should be replaced. I’d just do it anyway given the age of the amp, cheaper than a repair if one goes.

My tech replaced some in an old Marshall a while back - no bulging but dried out and gunky inside.

Curious if he finds anything, and whether you like the amp with more NFB.

 

[Deadpan]

- The service manual says that the NFB should be connected to the 8ohm tap, but mine is connected to the 4ohm one. He's gonna switch that over.

This is going to make a difference!

 

[Eagle]

It doesn’t sound in the clips like a typical VH4. One problem you get these days is when a component is “in tolerance “ most amp techs go “ fixed “ even if it sounds like shit compared to originally. Quite a lot a companies cherry pick certain parts to tighter specifications than the companies that make them to be within. Even Marshall do this.

 

[Orvillain]

It doesn’t sound in the clips like a typical VH4.

This amp isn't a typical VH4, is the issue here. The schematic which Peter sent me (no I can't send it to anyone!) clearly says that there is a lot of component differences between 1992-2005. Anything after that date range is much more standardized. Before that.... definite differences.

Mine is closer to your 95/96 blueface model, from what I can gather. It just happens to have a silver face plate.

So while I am not expecting it to match a modern model exactly, I would certainly like it closer.

 

[Orvillain]

My tech has replaced the 3.3k resistor with the recommended 4.7k, and he has replaced the KT77's - which all checked out fine, but were more like two matched pairs, rather than a matched quad. Suspect when I bought them they were never a quad, and I put them in without checking. Oopsie number one. Then he said the bias was very high! I followed the service guide exactly, so I'm guessing it drifted at some point. But possibly oopsie number two on my part as well.

I had him put JJ 6L6GC's in there, and I'm loving how it sounds. Proper roaring "Marsha"-esque tones, but obviously with the Diezel flavour. It no longer sounds fuzzy and flubby, like a Big Muff!!!

He also moved the NFB to the 8ohm sockets. It was 4ohms from the factory from what we could tell.

Amp roars like a demon now!

 

[EOengineer]

My tech has replaced the 3.3k resistor with the recommended 4.7k, and he has replaced the KT77's - which all checked out fine, but were more like two matched pairs, rather than a matched quad. Suspect when I bought them they were never a quad, and I put them in without checking. Oopsie number one. Then he said the bias was very high! I followed the service guide exactly, so I'm guessing it drifted at some point. But possibly oopsie number two on my part as well.

I had him put JJ 6L6GC's in there, and I'm loving how it sounds. Proper roaring "Marsha"-esque tones, but obviously with the Diezel flavour. It no longer sounds fuzzy and flubby, like a Big Muff!!!

He also moved the NFB to the 8ohm sockets. It was 4ohms from the factory from what we could tell.

Amp roars like a demon now!

Yeah but does it tool?

 

[Eagle]

My tech has replaced the 3.3k resistor with the recommended 4.7k, and he has replaced the KT77's - which all checked out fine, but were more like two matched pairs, rather than a matched quad. Suspect when I bought them they were never a quad, and I put them in without checking. Oopsie number one. Then he said the bias was very high! I followed the service guide exactly, so I'm guessing it drifted at some point. But possibly oopsie number two on my part as well.

I had him put JJ 6L6GC's in there, and I'm loving how it sounds. Proper roaring "Marsha"-esque tones, but obviously with the Diezel flavour. It no longer sounds fuzzy and flubby, like a Big Muff!!!

He also moved the NFB to the 8ohm sockets. It was 4ohms from the factory from what we could tell.

Amp roars like a demon now!

Excellent

 

[Orvillain]

Yeah but does it tool?

Hells yeah!

 

[Eagle]

Yes , mine sounds amazing . I thought yours must have a problem. Glad you found it.

 

[TSJMajesty]

replaced the 3.3k resistor with the recommended 4.7k,

put JJ 6L6GC's in

moved the NFB to the 8ohm sockets

Amp roars like a demon now!

I'm curious which change you think is responsible, or most responsible, for making it sound right?

 

[Orvillain]

I'm curious which change you think is responsible, or most responsible, for making it sound right?

Oh man, I'm just an edgelord dildo who can't even bias an amp correctly it seems. I have no idea!!!

I will say, that even though I now have 3 6L6 based amps - the Mark V, Recto MW, and now the VH4.... they all sound REALLY different from one another. So I don't think the power tubes are making a huge difference to the tone.

 

[GuitarJon]

These amps are just weird (in the best way possible imho):

 

[ejecta]

@Orvillain

I've played a few VH4's and every one of them sounds exactly like you're describing in the OP, and it's specifically the reason I've always been pretty vocal about disliking them.

I have never, ever heard a tight, defined sounding VH4. Every one of them sounds muddy and wooly to me. They all sound like not only is there too much low end being allowed through the preamp, but there's also something going on where they sound like way too many highs are cut out way too early in the preamp as well, like everything above 1k is shunted straight to ground right after the input or something, so you can't even use boosts or EQ's into the front end to gain back that definition even if you wanted it like you can with other muddy amps, because unlike other muddy amps all those highs are lopped away internally either way.

From there, the distortion will add back harmonic content into the upper frequencies and give you plenty of sizzle if you want, but it feels like fake high end to me, like there is zero fundamental signal in the treble frequencies of the guitar itself getting through, just sizzly upper harmonics generated from the low mids and lows being distorted in the preamp.

You probably don't want to hear this, but I don't think there's anything wrong with your amp. Your description matches every other properly functioning VH4 I've played. Your amp sounds exactly like it was designed to sound. Judging by the specific nature of your complaints in the OP, I think you'll be happier in the long run to sell the amp to somebody who really likes VH4's and start looking for something else.

Last thing I'll add is that there is a reason literally every popular guitarist you know about who uses VH4's pairs them with other amps, which I think kind of speaks for itself.

I wouldn’t say all the Diezels I’ve owned and played were overly fuzzy. I agree they have way too much bass and low mids in them which isn’t always a problem because Bogners are very modern in that way as well but he has a way of keeping amp feeling tight and dynamic with keeping that great growl. Diezels are much too dry feeling or overly filtered. I’ve never kept the ones I’ve owned very long. They aren’t my thing.