ss_preamp from the web (ss preamp) - nice!

[Renegadrian]

I got a helload of schematics in my pc, most of them never saw or will see the life...
I had this schematic always in my head, I said, yeah 5088 and james (which I like so much) - I have to try it sooner or later!!! Sooooo after a very loooooooooong time, I managed to put that schem on vero...This the original schem (graphically akward, but intellegible after a while) but I made a new one in a standard fashion.


Only mod I've done is a 56k res instead of the 15k between bass and treble (the "shift" resistor) to get a more balanced tone sweep, but yeah your mileage may vary (I saw someone putting a 470k "shift" pot) - also used regular NP 1µ cap instead of tantalums.

It's a very nice and useful preamp, tried with guitar it sound very good! gotta try it with bass...
Anyone built it before me!?

[swever]

Is it clean or does it distort? How does it sound? What transistor does it use? 

[Renegadrian]

it goes to clean to slightly distorted, it sounds great! Nice and easy circuit using 2n5088 or other generic npn.

[swever]

Interesting! Gotta give it a try. Where's my breadboard? 

[vigilante397]

Also going to have to try this out. Can we trouble you for a brief demo?

[Renegadrian]

Also going to have to try this out. Can we trouble you for a brief demo?

wish I could, but not able to do anything ATM

[vigilante397]

Also going to have to try this out. Can we trouble you for a brief demo?

wish I could, but not able to do anything ATM

Fair enough, maybe I'll have enough time this evening to throw it on the breadboard and see if I can record a quick demo

[Groovenut]

Looks to me with that biasing on the first transistor and the load, it'll clip the top of the waveform with anything over ~300mV RMS input with the gain control at minimum (more so with it turned up). So single coils will probably stay fairly clean but humbuckers and anything active will distort.

[Renegadrian]

My Strat is HSS, mini humb. in single size a la dimarzio fs and dual mini humb. (so it's 4 coils) made by musicyo kramer like 15 years ago. they have quite hot output but it stays fairly clean...

[zintolo]

Nice small preamp.
jfets with something like 30V (through a SMPS step up) will guarantee way more headroom, but in any case the real thing in preamps is the way they go into distortion, not the headroom itself.

[Renegadrian]

Nice small preamp.
jfets with something like 30V (through a SMPS step up) will guarantee way more headroom, but in any case the real thing in preamps is the way they go into distortion, not the headroom itself.

why?! A clean preamp could be so helpful in many ways...I want to try it on bass too, on guitar its quite good!

[zintolo]

I mean that the way people perceive cleanness depends on the way the stages goes into overdrive. How the transition between clean and distortion is, and the harmonic content of the distortion of the amp.

[Renegadrian]

Tried it now with bass, at low volume...it definitely rocks, it goes to clean nice preamp to some light grit added, like a small growl...bass tone control is useful indeed, while treble is less...maybe some value changes and the treble part will be at par with bass.

[Mark Hammer]

There was a very similar 2-transistor (2N5089) preamp project in Guitar Player magazine, back in the late 70's.  It was presented as an onboard preamp for installation into the guitar; something that was big at the time (check out some of those Ibanez Artist guitars with the onboard preamps).  The project was indicated as being the same design as Rex Bogue had installed in John McLaughlin's iconic doubleneck.

I built one and installed it into a guitar I had built i the early 70's, with, of all things, a maple Tele body that I was given.  I used it with a Fender wide-range humbucker and a Telecaster neck pickup.  Sounded decent, as I recall.  Long battery life.  It did not have any or much dialable distortion itself, but the output level was easily enough to push an amp or any pedals along the way into clipping.  Not mentioned yet here, I think, is the fact that the tone controls are Baxandall type, so they have boost and cut, as opposed to merely selective cut as in Fender tonestacks.

Given the low current draw, one might consider using it with one of those little 12V batteries you can often find at the dollar store.  The whole thing, including board and battery, would be smaller than the size of a 9V,

I have the photocopied article.  I'll have to dig it up and see what, if any, differences there are.

[swever]

I've finally breadboarded this thing yesterday. Tried using it as an actual preamp - in front of a power amp (an AMT TC-3). It seems to work very well for this application. Sounds great indeed, I love the light break-up it gives at higher gain settings. And it does stay fairly clean, even with active pickup (although the thick seventh string tuned to A does sound muddy and distorts when played loudly, even with gain at zero).

Takes all my fuzzes/ODs/dists well. Also, I can put the Sea Urchin Delay either in front of it or after and it works fine and does not clip either way (and seems to sound slightly different).

The tonestack is indeed a bit meh. As Adriano mentioned, the lows work well, but I ended up keeping the highs at maximum setting all the time. I put a 100k trimpot instead of 56k(15k) res and this does make a really nice control and has some useful range (somewhere between 10k and 50k). The higher you set it, the more highs you get, but for a price of obtrusive midrange presence/harshness. With lower settings, I get very deep, clear, slightly scooped sound, but then there is not enough highs even at the maximum treble setting. I wonder if there is a way to fix that or if I can just replace the whole tonestack with something else?

Adriano, there is a unlabeled capacitor in your schematic, next to 9V power. Must be some sort of power filtering - I am absolutely hopeless when it comes to understanding how these things work. What value would you suggest?

[antonis]

Looks to me with that biasing on the first transistor and the load, it'll clip the top of the waveform with anything over ~300mV RMS input with the gain control at minimum (more so with it turned up).

It seems to be designed for a 15 V (or greater) power supply..

[swever]

It seems to be designed for a 15 V (or greater) power supply..

Tried feeding it with two 9v batteries and did not really hear any difference at all except that it choked with gain set above ~90%

[Renegadrian]

I've finally breadboarded this thing yesterday. Tried using it as an actual preamp - in front of a power amp (an AMT TC-3). It seems to work very well for this application. Sounds great indeed, I love the light break-up it gives at higher gain settings. And it does stay fairly clean, even with active pickup (although the thick seventh string tuned to A does sound muddy and distorts when played loudly, even with gain at zero).

Takes all my fuzzes/ODs/dists well. Also, I can put the Sea Urchin Delay either in front of it or after and it works fine and does not clip either way (and seems to sound slightly different).

The tonestack is indeed a bit meh. As Adriano mentioned, the lows work well, but I ended up keeping the highs at maximum setting all the time. I put a 100k trimpot instead of 56k(15k) res and this does make a really nice control and has some useful range (somewhere between 10k and 50k). The higher you set it, the more highs you get, but for a price of obtrusive midrange presence/harshness. With lower settings, I get very deep, clear, slightly scooped sound, but then there is not enough highs even at the maximum treble setting. I wonder if there is a way to fix that or if I can just replace the whole tonestack with something else?

Adriano, there is a unlabeled capacitor in your schematic, next to 9V power. Must be some sort of power filtering - I am absolutely hopeless when it comes to understanding how these things work. What value would you suggest?

Thank you very much for the report!!!
about the james tone stack - yeah a trimmer or a pot in place of the "shift" resistor (between treble and bass pot) gives you different nuances and possibilities, but altough the tone stack is not bad, it seems you can't eat your cake and have it too...you can take it to a "compromise point" where it works best for your ears...Also, every component value of the tone stack can be altered for different results. Aaaaaand, for what I know and the little I tried in the past, james (passive bax) works better when driven by a cathode (emitter) follower. Didn't try it on this particular circuit, but again, the "cake" motto...You would end up with a different TS behaviour but you lose the first gain stage for a buffer.
If you want you can consider a whole TS replacement, I'd say take the Fender amps 2 knobs or the fender/alembic 3 knobs
about the unlabeled cap - any cap above 10µ is good at that position, it filters voltage...100µ is the typical value used, but a 220 or a 330 won't harm...

[swever]

Thank you for the schemo and info! Perfect timing - I was just looking for a clean preamp to use with my PA and pedals.

Played a bit more with it and I think I'm going to build this on a perfboard with this tonestack - it's definitely usable. I put a 100k log pot for "shift" and it works great. Good range and curve.

[Gus]

something from 2012
http://www.diystompboxes.com/smfforum/index.php?topic=96621.msg839900#msg839900