The higher setting is safer on tubes and bias. It’s better to undervoltage a primary than over voltage.Thank you! Another question.
I can choose from 220 v or 240 volts on the back of the amp. I have 230-235 in my outlets.
With the 220 settings the plate voltage is 500 and with the 240 setting it’s 500. Which would you choose?
It looks like they short tip to ring, and sleeve is footswitch ground. Its not your typical control type of footswitch - your guitar signal is passing through the switch and back into the amp. It’s a single button you need. It may have to be built. It’s not the way things are normally done FYI.When it's stereo jack, then would be a 2 button switch right?
I'm not seeing any 200k plate resistors? They're all Brown-Black-Yellow but not the stock 100k.It’s two mods in one. It’s a 200k plate resistor on the last 820 stage, and it looks like it’s also a footswitchable bypass of that stage that lets you bypass that stage directly to the tonestack.
The two smaller resistors on the top left are also not stock and also both 200k. Looks like every plate resistor is 200k in that amp.
Why they didn’t just put the cap on the Jack instead of fly leading it like that is beyond me. Total hack job but it works. The 200k plates across the amp would be preference for a pretty significant gain increase. I can see it went unstable, because with a gain increase like that they had to solder the grid stop resistor directly to the first stage.
Plate resistor increases are a different kind of gain increase though, as it shifts your bias point for the tube colder. I’m not a fan of going ham on increasing plate resistors IMO.
Didn't see this until after my edit above. I think that's what it is. It's either a mute or...I'm wondering if there was a pot in the footswitch if it would give you a footswitchable "boost". It actually wouldn't be 'boosting' per se just attenuating but the end result is the same...more volume vs less volume. But I'm not sure if that would work or be unstable.I tried a 2 button switch. But it removes all sound and nothing happens
And that's why you are the amp guru Randall......It looks like a TRS insert loop/preamp out to me.
The electrolytic capacitor is for DC blocking of the high-voltage on the cathode. It is a large value so there is no low-frequency rolloff when driving a low-impedance (10k-100k). The cathode follower output signal goes to the tip, the return comes from the ring and goes back to the tone stack.
If you use a mono 1/4" cable the return side will be muted so it acts as a preamp out, if you use a stereo TRS cable, it becomes a send/return for a series TRS insert FX loop, or for a volume pedal. When the cable is unplugged, the switching connections tie the tip to the ring for normal operation.
So the tip and ring tabs on the jack are not soldered together? It's hard to tell but it looks like they are.It looks like a TRS insert loop/preamp out to me.
The electrolytic capacitor is for DC blocking of the high-voltage on the cathode. It is a large value so there is no low-frequency rolloff when driving a low-impedance (10k-100k). The cathode follower output signal goes to the tip, the return comes from the ring and goes back to the tone stack.
If you use a mono 1/4" cable the return side will be muted so it acts as a preamp out, if you use a stereo TRS cable, it becomes a send/return for a series TRS insert FX loop, or for a volume pedal. When the cable is unplugged, the switching connections tie the tip to the ring for normal operation.
Thank you!A TRS effects loop allows use of a standard TRS insert cable that has a 1/4" stereo jack on one end and two 1/4" mono jacks on the other end. It saves one cable. I used single-jack TRS insert FX loops on my Sabre and Intruder amps because I hated having to run two cables for each loop.
https://www.sweetwater.com/store/de...able-1-4-inch-trs-to-dual-1-4-inch-ts-12-foot
A common 2 button switch will not work as I mentioned before - you’d have to wire the switch to short tip to ring and not tip to ground and ring to ground like most switches and correct designs.I tried a 2 button switch. But it removes all sound and nothing happens