The Amp Garage

BonesMachine wrote: ↑Mon Jun 26, 2023 9:05 pm so the ot primary blue and brown are the same thing correct and doesnt matter which one goes to what tube socket?

It matters. BRN goes to V4 + V5. BLU goes to V6 + V7.

White is by the spec sheet said to be hot . If you already have black as hot and the jack is bolted to the chassis it can take a ton of heat to swap the wires there if you find that the amp is hollowing. In that case just swap the blue and the brown wires since to the rest of the amp circuit and th...

i have a very novice question. i am replacing an output transformer on a 70's fender bassman amp. i have a new hammond 1750w replacement. it has secondary black (com) and white wires. i am not sure which wire hooks up to the positive of the speaker output jack on the amp black or white? any help ap...

After your post I checked one of my amps, and there is no D.C. at the output, turn on or running. Possibly an issue with amps that still use a standby switch. The filter capacitor on the fixed bias voltage divider doesn't allow the grid voltage to suddenly shoot up when the Standby switch is closed...

If you short your send jack, you have no output, so you're signal qualities don't matter. It's just an example of finding the conditions at the extreme. This sort of exercise is often helpful in clarifying how things are changing. FX Loop KOC Best All-Tube Loop.gif The London Power loop has a 1k lo...

Also if you use a 12DW7, the AU side would be used here for a better FX send, making the loop able to drive any load impedance effortlessly. My Mesa loop can easily drive a very low impedance load with a 12AX7 and my driver is only using 1.1mA as compared to 10.6mA with the AU side on the previous ...

In this Mesa design the benefit of the cathode followers low output impedance is nullified by the 100k resistor in line. The output of the loop send CF should be taken before the 100k resistor, from the junction of Rk and Rg, above the 100k resistor. This would also be the place to install a send c...

Mark wrote: ↑Wed Jun 07, 2023 7:02 am For this reason I like the idea of using the master volume to determine drive, though the master volume would equally work well after the effects loop.

I would like to be able to switch it in and out of circuit.

One way to do the bypass switch:

A bypass switch is usually handy.

If you put in a Send Level control, then the Master Volume can resume its usual function.

Mark wrote: ↑Tue Jun 06, 2023 8:11 am The insertion point will be after the master volume.

Placing the effects after the Master Volume means that the effect device will end up controlling the output volume of the amp. This doesn't keep a lot of people from doing it and even production amps have done it.

Finally got a bit of time to switch my tremolo over to slucky's trem-o-nator. I decided to keep the fender style footswitch setup and did not use a 10k cathode resistor. Everything else is per the trem-o-nator schematic. I've updated the schematic in the first post of this thread to match the amp a...

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Xvive's came in. 0.1mA 143.2k Average 155k High 129k Low Sample size: 5 1.0mA 8.3k Average 9.8k High 7.3k Low Sample size: 5 1.5mA 5.7k Average 6.7k High 5.0k Low Sample size: 5 1.61 voltage drop across LED @0.5mA Not sensitive to outside light sources. Looks exactly like the old VTL5C1's.

I'm assuming the useful range for the oscillator tube is in the neighborhood of 0-2mA But there is not much variation (relative to 50k) after about 80uA. Since the LED also has to bias the oscillator tube, I don't see a way to feed it less current and get it working in the steeper part of it's curv...