Let's put together a modular pre

[ted01]

Hey Dan,

I hear ya' on the test gear thing. Exactly my philosophy. Ultimately, I'd like to build a couple of preamp modules where I replace just about every fixed value component with a variable version. I've got voltage and current test points just about everywhere you'd want them. Harbour Freight had a sale a month or so ago where I picked up about 15 DMM's for $2.99 each! Believe it or not, the are all pretty darn accurate, at least as compared to my Fluke. It'll look like the Bride of Frankenstein when I'm done, but I'll be able to monitor the effect on plate voltage/current and cathode current all the way through the amp as I change things like the value of the plate resistor and such. At the very least, it should LOOK cool, even if it doesn't make a sound! My first challenge is to just duplicate what I already have to validate the modular concept and work out issues like ground loops and such. Since I will have a single heavy gauge wire going from each chassis back to the PS, I think I would have to lift the ground on one end of the signal cable, otherwise that would provide another path to ground (chassis to chassis and then through each other's primary ground wire back to the PS). Do you think that for short runs between chassis (less than 12") I could do without shielded cable? That'd be a darn sight easier, just use more of those banana jacks/plugs. I've been reading the Morgan Jones book, and perhaps my judgement is being influenced. My gosh is he anal. I look at what I've already built and I can't believe it actually works! I know that what's good in the Hi-Fi world may be overkill in the guitar amp world, I'm just trying to figure out what matters and what doesn't.

Oops, there I go again, rambling...
Sorry,
Ted

[nickt]

Ok understood - I might try the "amp lego" approach but (given I said this two years ago on AX84 as well) don't hold your breath mate!

One of these days I'll have to winter over in Oz, our Winter is your Summer. I'd really like to know what kind of electronics surplus can be had down there, apparently a lot of the old military transmitters used KT66s. I like KT66s...

I wish I had a source of vintage military avionics for cheap.

Hey CaseyJones - think you might be sorely disappointed with respect to aussie surplus. Most manufacturing was shut down in the early 80's. There were a couple of "wierd old guys" who used to service TVs and such from shops full of vintage junk but I think they're all 6 feet under these days. Practically impossible to buy anything out here unless you want a container or pallett load.

Of course sun, surf and sand is pretty good - if you're into that sort of thing

[Doug H]

Good idea, AX84 discussed this once or twice - haven't been there for a while so don't know if it went anywhere.

That was the "Tonebrewery"- Paul Ruby's baby IIRC. Modular pre, power, and power supply. Cool idea- don't think it went anywhere though.

[CaseyJones]

Hey CaseyJones - think you might be sorely disappointed with respect to aussie surplus. Most manufacturing was shut down in the early 80's. There were a couple of "wierd old guys" who used to service TVs and such from shops full of vintage junk but I think they're all 6 feet under these days. Practically impossible to buy anything out here unless you want a container or pallett load.

A pallet load sounds good.

You'd be surprised, there's so much old communications gear out there and I get it from all sorts of unlikely sources. My favorite is passing the word around scrapyards. They'll get racks full of old junk and they're happy to have some lunatic come in and seperate the aluminum from the copper and steel. Even if it's solid state there's usually good switches, fuse holders and cool connectors "up the ying". Just the kind of junk you'd want for a bulletproof super duty amp project.

Of course sun, surf and sand is pretty good - if you're into that sort of thing

The beach is nice but I picture myself traversing Tasmania followed by a mile long cloud of dust...