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Dr Tony Balls wrote: Mon Dec 04, 2023 11:25 am
If you want a specific sound, it's a pretty common practice when duplicating tube preamps to just make them with FETs instead. Ive done this plenty and the results are solid. I dont know what this Seymour Duncan think is but if one wanted a SLO, for example, you could knock that circuit out with FETs and it'll sound quite decent.

The AMT amp tube 2 fet pedals are quite nice and the schems are widely available. High gain stuff seems to sound a bit more authentic than the lower gain stuff.

When I was 17 I saw an ad in Guitar Player for a rack preamp called the Matrix, and I don't know why but I became slightly obsessed with finding one. When I bought my IVP, it was because I never found a Matrix, and I wanted an amp that I could use for either bass or guitar. I still have never heard a Matrix, though I did see one through the window of a secondhand music shop once, while on tour and when the shop was closed. So I've seen but never touched one.

All the guitar on the Failure album I recorded was through a Hafler preamp called the Triple Giant. Sounded decent for that kind of thing, saturated tube overdrive in degrees of gain. Styled after Fender and did sound a lot like a Bassman in overdrive.

In the late 80s the A/DA preamps were in every shredder's rack. Sounded consistently like shit. Thin and fizzy distortion. I know there was a tube in there but I'd be surprised if it had a normal B+ voltage. They sounded quite a bit like those little foot-pedal tube jobs that starved the plate of a 12AX7 with like 24 volts.

That Mesa preamp "as used by Kurt Cobain" was at the studio when we recorded In Utero but it sounded fucking awful. The broken Quad Reverb and the Randall both kicked its fizzy, thin little ass.

The thing that makes the IVP unique is the "tube" distortion circuit, which uses a saturated transformer as the clipping element. The other parts of the circuit, the bass/treble controls and the 5-band EQ, are conventional. The EQ comes before the distortion, so it has a profound effect on the nature of the saturation. The clean channel should be pretty simple to copy but I've found little use for the clean channel. I mean no use. Never liked it on anything.

The "tube" channel is unlike any other distortion, and the pedals I've tried that purported to emulate it have not really gotten that close. I'm sure the particular part choice for the "clipping" transformer has a lot to do with the sound, given that it's being used in a failure mode and everything fails differently, but it would be cool if somebody revived the concept, did the hard work of listening to a bunch of transformers being roasted and made a pedal with that sound in it. It's an ugly sound but hey I made a living.

steve wrote: Mon Dec 18, 2023 3:38 pm When I was 17 I saw an ad in Guitar Player for a rack preamp called the Matrix

It wasn't Audio Matrix, was it?

From memory the Matrix guitar preamp had a couple of sliders on it, like a small graphic eq, and I think it was all solid state.

fm Dr Tony Balls makes an AWESOME guitar preamp called the Pentode.
I bought a mono unit, and I take it with me whenever I do out of town sessions. It is fucking awesome.
We later called him up and he made us two more stereo units.
I use at least one on every session.