Tube Amp Archive

amplifiednation wrote:Was that bite from the amp bug?

It probably was. Glad it wasn't a bandsaw bug!

Structo wrote:Bad!

What was your other hand touching?

You don't wanna know.... =)

I think I was holding my chopstick.

I don't really remember, but I do remember thinking "I'm glad I wasn't holding onto the chassis."

This is what an amp bite looks like. I think it was from the 16uf 475v cap supplying the phase inverter tube (high 300's for voltage). I was 'in the zone' and attempting to adjust the plate voltage of a particular tube by removing another tube from a different channel of a Fender Deluxe Reverb. I di...

The OD channel is functional! It took some chin-scratching and resistance measuring to figure out what the problem was. In fact, there were a few mistakes: One of the cathode resistors was 150k not 1.5k; the .005uf coupling cap was hooked up to the bias supply instead of the output (haha here) and o...

Than you very much for the advice. You've accurately guessed my level of experience. Two months ago, I didn't know how a resistor functioned in a circuit or what a capacitor might be doing. I also hadn't owned a guitar amp until a couple months ago. No offense taken at any assumption made about expe...

And after jumping the power supply that feeds the preamp tubes over to the OD circuit, I've achieved 285v. For some reason, the 100k resistors I installed make no difference to the voltage. Measured on either side of the resistors, the voltage is only 2 or 3 volts difference (but at least it's lower...

The circuit is fully installed and the amp doesn't catch fire when turned on. Unfortunately, the B+ voltage is quite high. With 100k plate resistors, the voltage is 412v. With 1m resistors, it still measures ~350v. Should I be taking the B+ from a different part of the amp? I'm sure I don't understa...

All of the parts arrived, mostly from www.newoldsounds.com (they've got good prices, good selection, but have trouble shipping things quickly for the last couple weeks). I started by replacing the stock 16uf filter caps with fresh ones @475v. They all tested like 20uf caps, but I'm not upset. Maybe ...

I've been proceeding with the advice to unplug the amp in on/play and strum the guitar until until the amp doesn't make any more sound. I can't find any reading above 5v anywhere after doing that and have replaced resistors, capacitors, redone wiring, added, and removed--all without the slightest no...

There was a Deluxe Reverb ODS on Youtube before, probably still there but it sounded great. So I definitely think it is possible to get great Dumble tone out of that amp. Dumble was known to use surplus parts in a lot of his builds back in the day when those places were around. I think the internet...

That mod looks fantastic. I think I've given up on the cascade mod for the moment. I'm going to attempt to replace the vibrato circuit (just the vibrato circuit, not the whole channel) with a Dumble ODS overdrive circuit (copying the #124 OD circuit). I'll have the normal channel on a switch to roug...

I've had a wonderful opportunity to spend time inside a Deluxe Reverb with the AB763 circuit. I've tried a few different things to turn it into an amp with some rich singing overdrive and I've had limited, though worthwhile, success. The amp came to me already heavily modified. A bunch of caps had t...

In non-cascade mode, does the NORMAL channel sound normal? And you're diming that (volume and tones at or near 10) to hit the VIBRATO channel hard? You may need to play with some known-good tubes. In non-cascade mode, the normal channel is mute. The switch, at the moment, only enables the signal to...

The mod is functional and as you've suggested (no signal travels to PI wen signal travels to PI from normal channel). The amount of saturation, compared to a Mk 1 or Mk2 Boogie circuit, is quite weak. These Mk circuits use the same 12ax7 and a tone stack with similar options (no mid knob here, thoug...

Are you going to use the vibrato? . Very likely not. I doubt I'll use the reverb either, though I don't want to extract that entire circuit in case I decide it's useful. Here's a picture of the amp with the barn mods. I've since removed and restored a few. The leftmost switch previously from either...