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Quote from: rowdy_riemer on January 24, 2010, 12:02:35 PMmmm....
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.
... j201s are high gain jfet, i don't think that if you'll use MPF102 ,gain will not increase...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.
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??
Quote from: rowdy_riemer on December 22, 2009, 11:16:35 PMok, thaks, i'll try to use a few fetzer valve stages from ROG.... maybe i'll make a mix between opamp and jfet, i'd like to an inverting adder oamps with 3 bands control (bass,mids,highs) for tone control...
One thing I did for a nice clean preamp was to setup a few fetzer valve stages(see fetzer valve article at runoffgroove.com). I used an 18v supply. The first two stages use mpf102's and I added a third stage using a j201 for some overdrive. 2n5457's might be better than the mpf102's, but I didn't have any at the time. Two or three 2n5457 stages should give you plenty of gain without preamp overdrive. However, using the mpf102's and the j201 gave me plenty of clean noiseless gain. Then, you can just put whatever tone control you like afterwards. mpf102 or 2n5457 source follower stages might be good for buffering a tone control circuit. Then again, I'm sure you can get suitable results with op-amps. If you want to go with jfets, you should definately check out the fetzer valve article and use jfets with a relatively high cutoff voltage.
Or just do what J M Fahey suggested. He seems to be pretty squared away and knows his stuff.
Another thing, regardless of weather you use jfets, bjts, or op-amps, have a good clean regulated power supply. I went the easy route, and used two 9v batteries, but I'll probably eventually build a decent supply.
Quote from: armstrom on October 08, 2009, 01:40:34 PMso, only 1 V or less input signal for LM3886.... what is the value (volt) of the signal that's coming out of my preamp make by tubes?
The first thing to keep in mind is that you will have to greatly attenuate the tube preamp. Depending on how many gain stages you use and what kind of other losses are introduced (tone stacks, for example) you will end up with very high signal voltages coming out of your preamp stage. Most SS power amps are set up to handle 1V RMS or less input signal and will clip horribly at any signal above this level. As for the suitability of the LM3886 I think you're on the right track. These chips are known for being very linear and transparent. They're very low noise when built with a good circuit layout.
-Matt