Any good DIY standalone guitar preamps out there?

[jrc4558]

I went through a bunch of fender schematics, but everything is very typical with Baxandall tone controls and generally tubescreamer into a HiFi tone controls...
Can any of you good men recommend a DIY preamp to throw in front of an LM3886 or some other solid state poweramp?

Thanks in advance!

[MartyMart]

How about using something like a ROG English channel or a Dr Boogey ?
I put several things in front of my recent TDA2050 amp build and most sounded fantastic !
MM.

[mars_bringer_of_war]

+1 on the ROG stuff. I was using a few different "amp sims" in front of a Mosvalve power amp for a while, sounded quite nice, surprisingly good.

[petemoore]

Can any of you good men recommend a DIY preamp to throw in front of an LM3886 or some other solid state poweramp?
  I started with an 18v power supply for headroom and 'kick', used a Mosfet gain stage right before the amp.
  Has a nice clean 'bounce', tends to make it louder and cleaner than what I was getting @9v.
  Then I just put 'something/anything' on it. Verb/echo, something with 'internal gain-distortion', many many to choose from...

[MartyMart]

I dont see why this is in the Lounge !! ??
It's a question about a DIY ampsim/preamp ! 

[jrc4558]

Oh nice petemoore! I was thinking to use a fetzer valve before the chip, but thought it would be too low of a gain. Somehow I didn't think of a MosFET booster. Which one do you use?

[jrc4558]

I dont see why this is in the Lounge !! ??
It's a question about a DIY ampsim/preamp ! 

YEah, I know... I have no explanation to this.

[petemoore]

  The IRF510 may not be the best choice, I like it, just about any N channel mosfet...BS170 or 2n7000
  GEO explains how gain is structured, how mosfet is biased with gate [I use simple whatever pot...I forget...10k+] with a big 'ol resistor to set gate bias, pot as adjustabe V divider through 4m7 or so to gate makes mosfet easy to get a bias on.
  Then just set the S/D resistor ratio using current formula...or whatever...take a look at 1/2 of Gus's Mosfet Overdrive.
  Power bypass cap.
  I type faster than I remember details.
  Now, I had the boost

 in the amp chassis and had noise issues, I'd take special care about noise because the amp is multiplying large.
  So...I'm still using Mosfets as 'pre-amps' to get other amps I have around here fired up hotter [a dual mono mosfet amp, tube amp etc.], which is hot enough for me, I didn't A/B against mixing board, but I like the sound of mos, find them easy to work with [I socket and try not to touch the leads...static hazard IIUC on some mos devices], and get them to do what I'm wanting these days...having pre and amp power speaker and sound good.
  There is a small noise floor I'm tolerating, I believe the 'whatever' WW power supply is introducing almost all of this noise....cheep EZ power has it's advantages and disadvantages.
  Next thing I'd do [not that bipolars or OA's won't work differently as good] would be move to tube, but that is also different and less convenient.

[jrc4558]

Ok, petemoore! Thanks for the advice!
I will cook something up and see how it works.

[Pushtone]

How about using something like a ROG English channel or a Dr Boogey ?
I put several things in front of my recent TDA2050 amp build and most sounded fantastic !
MM.

+1 Marty

I've been plugging the EC straight into the power amp input (efx return).
Sounds better than going through the amps preamp.

[jrc4558]

How about using something like a ROG English channel or a Dr Boogey ?
I put several things in front of my recent TDA2050 amp build and most sounded fantastic !
MM.

I have one concern with such arrangement. Will it not make the whole amp sound like the emulation of a particular amplifier ROG was aiming at?
How much of a character does a stompbox adaptation impose on the whole amplifier?

[petemoore]

  Basically you won't like the amps distortion, it is simply used to 'cleanly' amplify whatever clean or distorted sound it is sourcing. The speaker can influence tone and distortion though..
  Getting enough output from a high output fuzzbox, OD, Boost, or distortion is certainly possible [probable even], and can sound better driving the amp with no further 'pre-amp' boosting...no 'pre-amp'...the output from the effect drives the amp to 'tonier' sound than through say a mixing board or a mosfet 'pre' like I sometimes use.
a DIY preamp to throw in front of an LM3886 or some other solid state poweramp?
 
  I would suggest throwing combinations or single effects of what youv'e got and will build in front of the amp alone...see what's working the tone for you.
  I do well with the pedalboard in front of it, first and last on the board are boosters, between are Fuzz/Dist/Comp. Phase Octave [oh reverb is last before amp].
  Just boost gets a nice 'dirt-clean' by 'leaning' on the speaker [powering it hard enough to influence the tone], but I prefer some slight dirt in boost too..what would mostly be called a 'clean channel' [has 'some' dirt].
  So I don't really have a 'pre-amp' installed [I did but removed it], I like having the flexibility on that...often the amp sounds better with a boosted distortion driving it...but it does sound great w/ distortion>booster>amp too, generally a bit of a louder-clean-er-ish-dist.
  It seems less complicated to just try out this/that out... then that/this/the other, than to describe the comparisons.

[MartyMart]

I have one concern with such arrangement. Will it not make the whole amp sound like the emulation of a particular amplifier ROG was aiming at?
How much of a character does a stompbox adaptation impose on the whole amplifier?

Yes of course it will - that's the point, just plug in the front end that YOU like, leave an input to the amp
and use whatever ampsim/boost fuzz or whtatever "floats your boat"
If you want to add it to the unit "forever" than experiment to find the sound that our after.
\mm

[oldrocker]

I know I won't get many to agree with me but my Professor Tweed works great for me in front of my SS amp.  I use it all the time and most of my other distortion effects that I plug into it seem to be enhanced nicely.
Although I haven't tried the other ROG circuits like the now Omega which I do plan on building.  There are so many ROG projects I want to try but haven't got around to yet.

[MartyMart]

I know I won't get many to agree with me but my Professor Tweed works great for me in front of my SS amp.  I use it all the time and most of my other distortion effects that I plug into it seem to be enhanced nicely.
Although I haven't tried the other ROG circuits like the now Omega which I do plan on building.  There are so many ROG projects I want to try but haven't got around to yet.

Here' s few that I would recommend without hesitation :
English Channel - for the AC30 "type" voice
Thor - for a "Marshall" voice
Matchbox - obvious !!
The original Thunderchief also, even though you can have "bias" issues, mine is a cracker, but does
have more gain than a stock Marshall ... more like a "Trainwreck" ..... sort of !
MM.

[petemoore]

  k...
  You'll probably want something which brings higher output level on it most of the time.
  Simple boost to Prof Tweed to...fet...whatever as Marty puts it.
  Leaving that 'in'...or not...and then adding whatever is deemed necessary for a more distorted sound...
  I think 'clean' sounds better as would be clinically described as 'dirt-clean'...ie a bit of distortion say @ 9v via Fet or whatever...or...@18v as 'actual' clean [there is no actual 'clean' but...] ie very little distortion...pristine. depends on what you want for 'clean'...I find a hint of distortion adds to the depth of playing style.
  If you go for 18v 'pristine' you might find your 9v booster sounds better for processing distortions than your 'pristine' booster...consider having the 9v booster 'inside' the distorter bypass Sw wiring...ie choose your circuits and bypass routings...I like to do a fair amount of A/B-ing, 'A/B/C-ing' and 'A/B/D-ing' with circuits in boxes w/bypass switches [outside the amp] before dedicating anything to an amp.

[Dave Z]

Here' s few that I would recommend without hesitation :
English Channel - for the AC30 "type" voice
Thor - for a "Marshall" voice
Matchbox - obvious !!
...

+1 on the Matchbox. Nice amp sim, loads of gain if you want it & sounds far better than any of hte distortion or OD pedals I have around (that would be a TS808 clone witrh various mods, SD1, RealTube, and a tricked-out AMZ Minibooster).

The Mbox keeps the lows tight (not mushy like my '808), the harmonics are fabulous and it has a very articulate midrange. I think mine has a dodgy final stage (not enough gain) so the cleans are not so loud, but crank it up (or even run a booster or TS9 into it) & wow the thing screams.

[oldrocker]

Thanks people I will definitely be looking at trying those suggestions.  I've wanting to try all of those anyway.

[gideon]

Hello,

Sorry to wake up an old thread, but its damn informative .

I am planing to build an lm3886 practice amp to use with my bass guitar.
I listened to some of the ROG sound clips on the ROG website , the lead guitar sound on the supreaux clip made me nearly fall of my chair.
Would have been just the sound i am after for a guitar, but i am not sure how it will work with my bass.

My bass guitar i a strange custom built guitar i picked up for almost no money (around 50$ or so). i found it lying in the back of some  old shop in prague and i had to put in 2 tuning keys and new strings that were missing when i got back home.
It has an acoustic body and some old unidentified pickups. and the sound is of an old electric bass guitar with some contrabass acoustic tones.

So basically i want a preamp good for bass (best for my bass), clean and simple to build like the ROG ones.
Maybe mod the amp to work with either the bass preamp or the supreax for a guitar.

i would be very greatfull to hear your advice on this.

[Gus]

Fender did this sometime ago jfets in a preamp.  Look at the schematics in the groove tube "The Tube Amp Book" .

  There is a older Fender Harvard amp that uses Jfets in the pre and a nice simple solid state amp section.  4th edition has the schemactic on page 412.  I can't find a date but the schematic has Fender Rogers and Rhodes and CBS on it 70s maybe?  Anyone ever see one? I have looked at guitar shows and stores  over the years and have not seen this model amp.

This Havard circuit might be fun to build.

  The nice thing about the preamp is how the fets operating points are set.  The use of the + and - power supply is a clue