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Need a nice sounding pre-amp for metal

Started by weatherlght, January 15, 2010, 07:00:41 AM

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weatherlght

Greetings

I'm an electronics student and I have built 2 tube-amps in the past. I like building guitar amps from scratch with its cabinets and everything. I also tried to make an SS amp but the tone wasn't good at all. However I used a few ss pedals and amps which sounded pretty well like behringer od100, marshall mg series. In my ss amp design I used the schematics of a ts-9 combined with a flat response power amp that only produced a nice sound with a GT8 :p .

I know that there is a good preamp circuit out there that can produce can give a nice overdrive/distortion sound (marshall mgs are fine imo, they use leds for clipping), but the problem is I cant find any schematics for such an amp. I tried the TS-9 circuit and it sounded bad (uses diodes for clipping), I traced the circuit of my friends bc-rich bcl12 amp which also sounds terrible. I couldnt get a hold on to a simple marshall (mg10, mg15) Least i could find was 50dfx which is hard to trace with all the effects and such.

I will really appriciate if you can provide me the schematic of a mg10 or 15 cd or any other analog circuit (behringer od100 has digital effects I believe :/ ) that can provide me with a nice fat overdrive/distortion sound for heavy metal, similar to Iron Maiden tones.

Thank you

J M Fahey

Hi weatherlght
Build the Marshall Lead12 preamp (I think the model is 5005); it's very good and simple.


weatherlght

thank you for the info :) however i need to add a few things to this.

-a diode clipping distortion pre-amp (i'm not sure whether the preamp will give distortion without the diodes or the leds),
-a switch to bypass the clipping stage for clean tones
-a headphones output (i believe i can add this to the end of the preamp as an *pre-out jack, then include an *po-in jack and make a simple effects loop. but some amps add that at the end of power amp using some attenuation circuit to lower down the headphones signal voltage :s, i need a simple schematic for it)
-a simple mixer to the power amp input (or preamp clean stage input) just like in marshall mgs, so i can hear the song as i play

rowdy_riemer

I would suggest looking for a separate circuit for the headphone out. Also, if you don't do some sort of speaker cab simulation for the headphone out, the sound of a high gain preamp will sound like complete crap. You might check out the condor project on runoffgroove.com. Also, while many of the circuits on ROG might not be suitable for metal, you might like the Thor. You should probably also build a separate good clean preamp for clean tones and switch between the two rather than one that tries to do both. I designed a simple expandable mixer circuit, though I hesitate to post it as I've only tested the design in simulation, and I'm sure there are some good proven designs. btw, it's cool to see another Electronics student on the site. I'm slowly working on an EE degree myself, and taking electronic classes is what got me interested in amp building, which got me back into playing guitar.

weatherlght

I forgot how to play the guitar actually due to dealing with all these amps and tubes as well as the school  :( I checked the link you gave me and found some nice schematics, 5010, 5203 and 5213a. 5203 and 5213 have the leds i need for the fat od/ds sound i believe. I just need to figure out a way to simply those circuits as much as I can. Perhaps throw out the fet switches and all those low output impedence emitter follower transistors. Just put a 2 way switch to bypass the ds preamp and directly connect the input to clean preamp. Add a simple 2nd input before the power amp for cd input, and use that circuit of 5010 for the headphone output. I will use simple a tda2051 circuit running at 25-30w instead of the transistor power amp stage of 5010 though. If i can get my hands on a marshall mg10-15, i'll try to implement the fdd as well.

I'll also add a simple pre-out - pwr-in effects loop stuff. Do i really need a emitter follower before the pre-out jack ?

rowdy_riemer

I haven't checked out all those, but I would definately leave in the emitter follower buffer stages. Removing those might have a bad effect on your tone. You could certainly build your circuit of choice on a solderless breadboard and experiment.

weatherlght

update, still need an mg10-15 schematic please :)

baene123

#8
so, do you know dr boogie?? it's a mesa boogie jfet emultator, and it's excelent if you're searching a metal suond like high gain distortion... http://gaussmarkov.net/layouts/drboo/drboo-schem.png ...  ;D

rowdy_riemer

#9
I recently built a Dr. Boogey using the info from Gauss Markov's site. It pretty much rocks. However, I think the bass response is a little lacking. I really like Mensur's adaptation of this circuit. See http://www.ssguitar.com/index.php?topic=991.0 . His sound clips are F#*$ing awesome. He's using an 18V supply and lower gain FET's. He also adds a source follower buffer after the tone stack, which allows for low impedance output. The Gauss Markov version has a scaled down version of the tone stack for low output impedance. While I do not have a build of Mensur's version to compare it to, I imaging the Source Follower buffer is a much better solution.


--EDIT--

Oops, he's using a 24V supply.

baene123

Quote from: rowdy_riemer on January 22, 2010, 03:25:41 PM
I recently built a Dr. Boogey using the info from Gauss Markov's site. It pretty much rocks. However, I think the bass response is a little lacking. I really like Mensur's adaptation of this circuit. See http://www.ssguitar.com/index.php?topic=991.0 . His sound clips are F#*$ing awesome. He's using an 18V supply and lower gain FET's. He also adds a source follower buffer after the tone stack, which allows for low impedance output. The Gauss Markov version has a scaled down version of the tone stack for low output impedance. While I do not have a build of Mensur's version to compare it to, I imaging the Source Follower buffer is a much better solution.


--EDIT--

Oops, he's using a 24V supply.

what's???? dr.boogie is rock?? no no, i don't think... listen it http://www.youtube.com/watch?v=FU8G_6XMISc&feature=related     what jfets did you use??

rowdy_riemer

By saying the Dr. Boogey rocks, I was saying it sounds really good.  ;) I used j201's. If I did it over again, I might use an MPF102 for Q5.

baene123

Quote from: rowdy_riemer on January 24, 2010, 12:02:35 PM
By saying the Dr. Boogey rocks, I was saying it sounds really good.  ;) I used j201's. If I did it over again, I might use an MPF102 for Q5.
mmm....  ???... j201s are high gain jfet, i don't think that if you'll use MPF102 ,gain will not increase...
have you ever tryed to built "krank distortus maximus? it's high gain distortion with 3 bands equalizer
,try to check out and listen sample on youtube.... I recently built and i really like that!

rowdy_riemer

I'll check out the ""krank distortus maximus". Keep in mind that Q5 is setup as a source follower. There will be a voltage gain of a little less than 1 regardless of the FET used. However, I think you will have more current gain(lower output impedance) with the MPF102. Also, Vth(cutoff voltage) is lower for the J201. Some may disagree, but I think FET's in a source follower configuration should have as high a Vth as practical and as high a Idss as practical. Look on page 208 of Teemuk's book to see what he says about J201s in a source follower configuration.

weatherlght

Thank you for the schematic :) This is something that i will definately built. Still i'll also want to build a classic mg10-15 preamp and combine these 2 along with a tda2050 30w poweramp in a 2 channel nice sounding combo amp :)