DIEFET: Jfet simulation of the Diezel VH4

Post by **audioguy** » 16 Sep 2008, 19:56

9 knobs is insane!!! I MUST BUILD IT! hahaha

seniorLoco · Post by **seniorLoco** » 17 Sep 2008, 06:58

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

and call it 'openhouse' with a $400 price tag

...these Jfet's with "crappy" trimmers (aka variable resistors) kills some "known" high gain amps...imo
build it ...set it ...rock em!

ech0es · Post by **ech0es** » 17 Sep 2008, 11:24

Here is the sticker to put on your pedal if you want an "original VH4 design"

ech0es · Post by **ech0es** » 25 Sep 2008, 20:31

modifications of the schematic, it kicks ass !

http://pagesperso-orange.fr/sxsyl20/die ... estyyy.mp3

and here is a sticker:

Post by **audioguy** » 25 Sep 2008, 21:17

sounds good... do you have an updated layout?

ech0es · Post by **ech0es** » 25 Sep 2008, 21:28

not yet but it's just value modifications

1- Change the capacitor of the deep control from 470p to 220p
2- Decrease the 51k to 20k with bias to 4.5 or 10v, the jfet will react better
3- Change the capacitor of 15n with a 3n3 and the 330k resistor with a 100k

Post by **audioguy** » 25 Sep 2008, 22:00

This one is on my 'to-build' list, but Im waiting for a smaller layout. I just keep running out of daylight and never get around to redrawing it.

ech0es · Post by **ech0es** » 26 Sep 2008, 15:17

http://www.techniguitare.com/projets/Di ... -V1-21.mp3

Post by **audioguy** » 26 Sep 2008, 15:44

Nice dude!

sadrew · Post by **sadrew** » 26 Sep 2008, 20:03

Awesome!

How do you compare it to a dr. boogey, if you have built one?

I don't like the eq section of the doctor: not really versatile and the controls don't make so noticeable difference. I'm not happy with it at all so maybe i will replace it with the diefet.

Is the diefet eq more useful in your opinion? Or is always focused on a mid-scooped and bassy sound?

ech0es · Post by **ech0es** » 26 Sep 2008, 20:38

the diefet tonestack is the exact replica of the diezel VH4 tonestack because we found the schematic of this section

and you have two more controls: deep and presence to be sure to find your dream sound

BUT you have to keep in mind that the original amp, the diezel VH4 is a very bassy amp, and i guess that the tonestack has a "marshall structure", like the dr boogey. (to be verified)

Test the diefet to be sure and give us your opinion

chromaticdeth87 · Post by **chromaticdeth87** » 29 Sep 2008, 23:13

The tonestack plays a very small part to an overall sound. It does determine how much bandwidth is passed and what is boosted or limited after the gainstages, but it really means nothing when you think about the Phase inverter, power amp interaction, and whether or not the fx loop is always on or always off, serial or parallel, the voltages that are running through the amp. even a tube preamp can sound like shit if not mated with the right PI and poweramp. The uberschall preamp sound thin and buzzy on it's own I was told on another forum, it's the power amp and inductance controls that gives it a narrow bandpass and it's unique sound. Most diezel designs are very complex, but hot rodded marshall circuits are what dominate the gain stages, look at soldano and other hi gainers and you'll see alot of jcm 800 architecture with lee jackson and soldano mods, along with some of deizels own designs obviously. I would go back to a thor or Brown sound in a box and try to boost the gain and bass controls and see what you arrive at.

ech0es · Post by **ech0es** » 30 Sep 2008, 17:45

chromaticdeth87 wrote: Most diezel designs are very complex, but hot rodded marshall circuits are what dominate the gain stages, look at soldano and other hi gainers and you'll see alot of jcm 800 architecture with lee jackson and soldano mods, along with some of deizels own designs obviously.

the diefet is bases on the soldano X88 for the base, but heavily modded

ech0es · Post by **ech0es** » 30 Sep 2008, 21:01

through voxengo boogex and amplitube for the speaker sim:

http://www.soundclick.com/bands/page_so ... ID=6934858

Post by **audioguy** » 01 Oct 2008, 16:21

impressive!

seniorLoco · Post by **seniorLoco** » 02 Oct 2008, 02:24

yup .... gonna build me one

kantul · Post by **kantul** » 02 Oct 2008, 16:12

I build last week, nice project

Much better low end than dr.boogey..

pict:

My diefet sample:
SAMPLE
SAMPLE

Transistor:
Q1: MPF102 > trim 10k
Q2: j201 >100k
Q3: MPF
Q4: j201
Q5: MPF
330k trim change 330k resistor,

Post by **audioguy** » 02 Oct 2008, 16:23

What enclosure are you using there? Is that the layout originally posted?

kantul · Post by **kantul** » 02 Oct 2008, 16:43

Yes, original layout from technicguitare.
enclosure 12 cm x 9 cm box.

ech0es · Post by **ech0es** » 03 Oct 2008, 18:38

Nice!!

Is it the v1.11 or the 1.21 ?

The 25 october we will make an a/b test between the diefet and the original amp, so be careful to last value modifications