Collection of all kind of Diezel modifications

  • Thread starter Thread starter Tu_pe
  • Start date Start date
headcrash said:
This mod (moving nfb signal from one OT out to another, in this case from 8 Ohm to 4 Ohm) should work on literally any class AB push pull tube power amp with nfb (negative feedback).
Downside is, that your nfb controls (Deep and Presence) will have a little less effect. Which may or may not be a good thing, depends on your taste.
I found the Diezels I have had, and/or played to be too smooth and muffled.
Moving the nfb from 8 Ohm to 4 Ohm tap could be a good and simple mod, to up treble and high mids a little.

To tighten up the low end from the preamp gain side, this mod will not help, IMO. I think, using lower output, PAF type pickups help a lot (or increasing pickup distance to strings, can make a huge difference !).
IF I were to mod a Diezel for a tighter distortion, I'd rather change some of the mud-killing high passes early in the signal path. But tbh, the rather fat and muffled (or warm) base sound is a rather Diezel-specific sound quality, and if you don't like this, maye another amp is better for you?
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Thanks for your response. I do like the amp but a bit more higher mids and clarity would be nice. An overdrive helps but would be nice if the amp also has a bit more clarity.
As it is an easy reversible mod I will give it a try and see if I like it or not.
 
Michiel Kemper said:
Thanks for your response. I do like the amp but a bit more higher mids and clarity would be nice. An overdrive helps but would be nice if the amp also has a bit more clarity.
As it is an easy reversible mod I will give it a try and see if I like it or not.
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...great! Would love to hear how it turns out for you
 
fusedbrain said:
I moved the NFB connection on my 2018 VH4 from the 8 ohm jack to the 4 ohm jack. Not a huge change, but it opens the amp up a little bit and I prefer the tone.
With that one little change, I now feel like the amp is "perfect" for me.

Edit: a few guys have PM'd me about this, so here's rundown.

The pic shows the output jacks and output transformer of my VH4.
The white wire on the output jacks is the negative feedback wire. The orange wires are the leads from the output transformer.
Originally, the white wire was connected to the 8 ohm (middle ) set of jacks along with the middle orange output transformer lead.
Simply un-solder the white wire from the 8 ohm jacks and solder it to the 4 ohm jacks as I have in the picture.
That's it!!
If you don't like it, put it back. It takes 30 seconds.
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So interestingly, I just went to try this on my 2001 VH4, and it is already connected to the 4 ohm jack.

1735214015098.jpeg


Right side white == 4ohm tap.
Right side green == 8ohm tap.
Right side brown == 16ohm tap.

Left side white == NFB wire.
 
VH4, channel 4, there's a mod to make it more articulate and track faster for fast leads. Peter has a picture on how to do this for customers.
 
I made a pot for NFB. This has made the VH4 one of my all time favorite amps!
 
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