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have chosen my pre-amp

Started by troublerat, July 28, 2009, 10:22:30 PM

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http://sound.westhost.com/project27.htm  This has been mentioned before but now that my power amp is finished, I have been reviewing pre-amps. I have several boxes that I have been toying with but for some reason have put this one off until the last. I have had it built [circuit unboxed] and playing through this makeshift power amp [low watt ] thing I had laying around. The schematic calls for 15+15- but all I had available at the time was  9+ 9-. I am thinking about rebuilding it and trying it with the 18+ 18- I have available. To get to the sound, when elliot says it has ample gain available hes not kidding. The tone is sparkling, and it really kicks this lm3886 way up a notch. Compared to some of my typical stompbox circuits they cant really hold a candle to it. At max vol. it has a small amount of breakup [I mean small]. Very loud and clean and you can tell it was designed for a guitar amp. Loud and clean is usually where I practise at anyway. If you build it I would advice against the clipping diodes at the end as they seem almost an after thought in the design process. But everything else is full steam ahead. I may add an od circuit on an dpdt if I cant fig. out a good way to add some overdrive to this one....or I may leave well enough alone......................One more point at total maxed out vol. guitar pre-amp and power amp [well above bedroom level unless your deaf] noise really isnt a problem. It seem I filtered my power amp well and fairly pleased with it]


Good to know you've had some luck with that circuit.  I had seen it online before and wondered how good it would be, it reminded me of the preamp in my Dean Markley amp, so I figured it must be at least halfway decent.

Turns out it is very similar, even based of the same TL072 chip!  What that means is that it should be easy making it do a good overdrive circuit like my dean has.

Life is what you make it.
Still rockin' the Dean Markley K-20X


I have a couple of these PCBs at home that I haven't built yet. My latest goal is to build something super clean and loud (think Roland JC-120). I'm probably going to pick up a second LM3886 kit and build a stereo 2x12 combo amp using this preamp.

So, my question is, do you have any sound clips of this preamp running through an LM3886? From your description it seems to produce a great clean tone.


J M Fahey

Hi Armstrom/Matt. Just build it, the sound is similar to the JC or a Yamaha G100, that´s to say, an "SS Twin" of sorts, depending *heavily* on very good speakers. That preamp + 2 x LM3886 and 2 x Eminence Legends (or better) or Jensen Mod 1270 or better, will be an awesome beast in any stage. You´ll have to bring your own distortion.


I"m sure glad you dont have to be an electronics genius to have good ears, I knew I had something and I think I"ll stay with it. This thing in stereo with a tasty small amount of od in front[ maybe spike it with some compression and you truly would have a rug scorcher.I used opa 134 for the op-amps. http://www.alldatasheet.com/datasheet-pdf/pdf/231870/BURR-BROWN/OPA134.html.......I dont have a way to post any sound samples yet and one more word on this build just about the only other thing I am going to do with this amp is put an effects loop in[the one mentioned in teemuks book]