Pork: the pre-Hog

Force High Strength 53%


[2005-02-11] I've played the electric guitar quite seriously for half a year, and so far haven't owned a traditional amplifier. Instead I've used available gear at the school where I practice. At home I can't play with proper volumes, but I occasionally hack around with computer effects.

I'm not interested in following a strict tradition of tube amps and the like — if you want traditions, why use electricity at all? Anyway, for some time I've been thinking of building a preamp for a number of reasons:

There's actually a possibility that I might appear on stage later this year, with a requirement of the sound going through the PA, which is why I now started to realize these ideas.


I'm using the schematics of this ESP amp, namely its preamplifier section, with slight modifications. It's built on a veroboard for flexibility and simplicity.

Power supply

I've adapted yet another ESP project to my needs. The only change is using the 8-volt 7808 and 7908, since I happened to have a 9 VAC power brick from a dead modem. 9-volt regulators would have worked too, but the local electronics store didn't have them at the moment :)


Construction went on surprisingly quickly. I bought the components and a breadboard yesterday, and now I have a fully soldered (on veroboard) piece ready.

Breadboard 1

Breadboard 2

Veroboard 1

Veroboard 2

Experiences and tweaks

The first breadboard prototype didn't give enough maximum distortion to my tastes :) So I left out half of the clipping diodes. You can still get a nice clean, round sound with a low gain setting. My guitar is a Charvel Jackson PS-2, FYI.

With my power amp, the amplifier line is almost entirely made of op-amps. There's only one discrete transistor as an emitter follower at the output of the preamp, so it's not doing much to the sound. Incidentally, op-amp systems are nothing like transistor amps when it comes to sound; they are closer to tubes in some ways.

After a little testing, the distortion sounds quite similar to the valve saturation effect from Steve's LADSPA plugin collection (which I use via Ecamegapedal). It reminds me of the old 'rautalanka' sound and the Beatles' guitars. Which is a nice thing to get from my heavy-metal axe :)

[2005-04-06] I've added a switch to disable one of the clipping diodes. The resulting asymmetric clip is warmer, but a distinct edge remains.


[2005-04-06] The neat mesh-like case used to house a cognac bottle. It's a little thin and weak for heavy stage use, but I was in a slight hurry to enclose it for some light stage work. On the other hand, I bet it looks cooler than a standard chip-amp case :)

Future ideas

Risto A. Paju