DIEFET: Jfet simulation of the Diezel VH4

Stompboxes circuits published in magazines, books or on DIY electronics websites.

DIEFET: Jfet simulation of the Diezel VH4

Postby ech0es » 12 Sep 2008, 11:43

Image

Created on the French DIY community http://www.techniguitare.com

http://www.techniguitare.com/projets/Di ... -V1-11.pdf

Sample 1

Sample 2

Sample 3

Schematic with components

PCB

BOM

It was not created with the ROG techniques because the schematic of the VH4 is not known, so we created a preamp with a spectral analysis of an original VH4 to see which frequencies are typical of the VH4 sound (channel 3 & 4 ).
We worked 6 months on it to do the last schematic.

For this message the author ech0es has received thanks:
rocklander (21 Oct 2011, 10:13)
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Re: DIEFET: Jfet simulation of the Diezel VH4

Postby pz » 12 Sep 2008, 11:53

And i see you have taken and used the redrawn Varicab schematic from my site...
But that's ok with me.
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Re: DIEFET: Jfet simulation of the Diezel VH4

Postby ech0es » 12 Sep 2008, 11:55

I didn't know that it was from your site, i found it on our DIY forum.

Thanks a lot !this schematic permit to do the VH4S version
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Re: DIEFET: Jfet simulation of the Diezel VH4

Postby analogguru » 12 Sep 2008, 12:12

I don´t know what is a Diezel VH4 - does it sound like a V8-Diesel-motor ?

:hmmm: .... and the design still uses drain-trimmers - even at the source bypassed stages - which will cause every unit to sound different due to the different drain-currents....

If only the frequency response would be important, someone could use op-amps instead of the FET´s too...

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Re: DIEFET: Jfet simulation of the Diezel VH4

Postby ech0es » 12 Sep 2008, 12:15

I don´t know what is a Diezel VH4 - does it sound like a V8-Diesel-motor ?


Used by metallica, tool, smashing pumpkins, muse etc...

Matthew Bellamy / Muse
Adam Jones / Tool
Billy Corgan / Smashing Pumpkins
James Hetfiled / Metallica
Kirk Hammeth / Metallica
Mark Tremonti / Creed / Alter Bridge
Wes Borland / Limp Bizikit / Black Light Burns / Marilyn Manson
Mike Mushock/ Staind

:hmmm: .... and the design still uses drain-trimmers - even at the source bypassed stages - which will cause every unit to sound different due to the different drain-currents....

If only the frequency response would be important, someone could use op-amps instead of the FET´s too...


It's the conception of the Jfet simulation: use drain trimmers and adapt them to 6v. (4.5v for 9v sim).
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Re: DIEFET: Jfet simulation of the Diezel VH4

Postby analogguru » 12 Sep 2008, 12:48

It's the conception of the Jfet simulation: use drain trimmers and adapt them to 6v. (4.5v for 9v sim).

It is simply a junk-conception, even "stm" from ROG found this out in the meantime:
http://www.diystompboxes.com/smfforum/i ... c=70065.80

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Re: DIEFET: Jfet simulation of the Diezel VH4

Postby ech0es » 12 Sep 2008, 13:24

Feel free to upgrade but your method is to respect the frequencies of simulated stages BUT , we did'nt start from the schematic of the Diezel. (post 1 of this topic).

You can read the conception here:
http://www.techniguitare.com/forum/viewtopic.php?t=6606
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Re: DIEFET: Jfet simulation of the Diezel VH4

Postby DSV » 12 Sep 2008, 13:41

I followed the project on techniguitare. It is not a traditional simulation with the ROG method. In fact it does not stem from the schematic of the Diezel, but from the Dual Rectifier. Then a frequency analysis of a VH4 has been performed, in order to design a post-equalizer capable of mimicking the frequency response of this amp, and has been added to the Rectifet (the techniguitare version of the Dual Recto simulation).

Of course, it could be done with other devices, but that's how the project originated. Maybe in a future version ...

EDIT: echOes, you beat me to it ...
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Re: DIEFET: Jfet simulation of the Diezel VH4

Postby ech0es » 12 Sep 2008, 15:07

DSV wrote:I followed the project on techniguitare. It is not a traditional simulation with the ROG method. In fact it does not stem from the schematic of the Diezel, but from the Dual Rectifier. Then a frequency analysis of a VH4 has been performed, in order to design a post-equalizer capable of mimicking the frequency response of this amp, and has been added to the Rectifet (the techniguitare version of the Dual Recto simulation).


It was at the beginning, now it's a totally new preamp ! the post eq idea was abandonned for example
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Re: DIEFET: Jfet simulation of the Diezel VH4

Postby rackham » 12 Sep 2008, 19:11

Regardless of the trimmers issue, it sounds pretty good to me.
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Re: DIEFET: Jfet simulation of the Diezel VH4

Postby ech0es » 12 Sep 2008, 19:30

it's not an issue, it's the same thing for all the ROG sim, and for this sim it's not a problem because we didn't do it from the original schematic.

You just have to adjust them at 6.5v
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Re: DIEFET: Jfet simulation of the Diezel VH4

Postby audioguy » 12 Sep 2008, 20:33

The PDF file prints the PCB really poorly, and its nearly impossible to follow the layout. Do you happen to have the Eagle file used?
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Re: DIEFET: Jfet simulation of the Diezel VH4

Postby ech0es » 13 Sep 2008, 10:37

see my first post:

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Re: DIEFET: Jfet simulation of the Diezel VH4

Postby audioguy » 13 Sep 2008, 14:32

Yeah when I load that PCB file into photoshop it gives me an error. Standard photoviewers open it fine, but photoshop says something about missing data.
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Re: DIEFET: Jfet simulation of the Diezel VH4

Postby John Lyons » 14 Sep 2008, 03:01

Just use the PCB and "Schematic" (which is actually the Layout map).
The PDF is pretty bad! Hard to read and fuzzy.
You could probably just print the schematic and compare it to the BOM and layout.
But why not just make a decent PDF huh?

Sounds ok but the sound clips are overly bassy...

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Re: DIEFET: Jfet simulation of the Diezel VH4

Postby ech0es » 14 Sep 2008, 11:11

John Lyons wrote:Sounds ok but the sound clips are overly bassy...



You have 3 controls to adjust the bass level: BASS DEEP and the extra control (330k or pot 500k)
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Re: DIEFET: Jfet simulation of the Diezel VH4

Postby audioguy » 16 Sep 2008, 17:06

3 bass controls?? yikes
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Re: DIEFET: Jfet simulation of the Diezel VH4

Postby ech0es » 16 Sep 2008, 20:19

The bass control is the same as the original on the VH4 (as the teble and middle)because we found the schematic of the tonestack, the deep control is also on the vh4 (see the user manual) it boost around 100Hz, and the extra control will decrease the bass level before the tonestack and the deep control.

;)
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Re: DIEFET: Jfet simulation of the Diezel VH4

Postby audioguy » 16 Sep 2008, 20:49

sounds like it could be a very cool box... I might re-work the layout a bit to get it to fit into a standard sized box
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Re: DIEFET: Jfet simulation of the Diezel VH4

Postby ech0es » 16 Sep 2008, 20:52

we work on a 1.2 version to add a "dynamic" control 8)

So if you make the extra control as an outside control, it could be a 9-knobs distortion :twisted: (on test!)

Vol
Gain
Bass
Mid
Treb
Deep
Presence
Dynamic
Cut (the extra control to cut the bass before the tonestack)
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