EVH 5153 preamp with LND150

[Katoda]

Just to see how it would have turned up, I attempted to recreate the preamp from the ultra-high-gain EVH 5153 (the Fender version) with the base of research being KMGs fantastic JCM800 preamp with LND150 mosfets, implementing the diode grid current limitation and therefore closely emulating the 12ax7 tubes. I ran out of space pretty quickly, because I was using two perfboards superglued together in a recycled enclosure from a 'true' tube Pittbull preamp project. It looks ugly as ****, but it cost me about 10€ (except the LND150, I had everything at home and/or at hands reach) and it sounds awesome. Having never played the original amp I cannot claim it sounds the same, but from what I heard on YT, its pretty close.

Pics:
http://i63.tinypic.com/e13jtt.jpg
http://i66.tinypic.com/ofop4p.jpg

Some sound samples - Lasse Lammerts DI tracks reamped  through the thingy, with some impulses (Peavey 4x12, i think - or recto):
https://soundcloud.com/user-119965807/evh-5153-preamp
https://soundcloud.com/user-119965807/evh-5150

[phatt]

Hi Katoda, Welcome to the forum
Hey thanks for sharing, Yes KMG has done some very impressive work.
Sounds big but I assume you only built the preamp?
Also I'm a bit lost as to impulses, How does that happen exactly?

I'd like to hear a recording of the circuit coming from a Real Guitar> Amp> speaker and miked up recording.
Phil.

[Katoda]

Hello, thank you 
Yes, I only built the preamp, which is going to be played through the FX loop of my Fryette Deliverance project. I don't currently have the amp at home, but as soon as I get it I will post some clips. I am also anxious to try it with a real tube power amp, so far I have only played it through a small tda2030 based thingy.
The impulses are basically recorded speaker frequency response and behaviour, so a sort of fancy eq. It doesnt sound quite as good as a miced up cab, but at the time it was (and sort of still is) the only option. I have to ask a friend to borrow his mic again.  .  But kind of the reason I didnt play any actual riffs myself is that I've heard these DI tracks in many gear demos and I thought it might be a good comparison with the real thing. But I will put up something for sure, this little preamp is my favourite new toy
Also, perhaps it is worth the mention that this thing has waaay more distortion than I need, so I have already changed the 1M gain pot for a 100k one. Way better, now I can get it in the zone where it cleans up nicely with the guitar volume pot.

[phatt]

Thanks for the explanation of recording process, sounds complicated
I'm actually more interested in how it sounds through your tda2030 thingy (or similar) as that won't colour the sonic result as much giving a more realistic impression.
Yes I also don't need total distortion so cleanup with guitar volume is much preferred.
Keep us posted,,
Phil.

[Katoda]

Hi,
I didn't have a proper mic so I just turned the volume waaay down until the phone mic wasn't clipping and recorded a sample of the cleanup with the guitar volume knob.
 https://soundcloud.com/user-119965807/evh-5150-preamp-phone-recording-of-guitar-volume-cleanup
Gain was on 11 o'clock, on the recording I gradually increase the guitar volume.

EDIT: Listening to it again, the gain was set kinda high, metal territory...

[phatt]

That is quite impressive,
Yes very dynamic and tone alters as the volume increases,, hum interesting indeed.

Which preamp section of the amp did you build?
What voltage does it run on.?
Better still any chance you have a schematic?

Please

Phil.

[Katoda]

Thank you
I followed the lead channel of 5153 schematic (fender), with a basic gain stage like the one KMG came up with, using Bav99 and Bat54s diodes, from this post:
http://www.ssguitar.com/index.php?topic=2039.0
R3 was 180ohm, except on the third stage, where there is an unbypassed 39kohm source resistor, there its 270ohm. In the original schematic, the cathode resistors are mostly 1.8k with 1uF bypass and 2.2k, here the source resistors are mostly 2k2 with 1uF bypass and 2k7. Plate resistors are the same. The resistor before the 1uF capacitor is 680ohm.
For the power supply i have a 15V AC input, from which one path leads to a rectifier and 7812 regulator to get -12V for biasing the mosfets, and the other goes to an ugly 230-12V Ac transformer on top of the enclosure, which gives out about 340V.Filter caps are 2 680uF/200V in series, each in parallel with a 270kohm resistor.
The gain pot in 100kohm with 4.7nF treble bleed cap, as opposed to a 1M with 1nF.
And instead of the cathode follower on the 5153 version, the tone stack is plate-driven, as in 5150.

Sorry, I don't have a schematic, but this is pretty much it

[phatt]

Thanks for the explanation.
Phil.