Voltage was a little high the other night.

When playing master volume high gain amps I start noticing a difference when the voltage drifts +/- 3 V. Any less and I don't notice. I'm thinking with a cranked plexi type of amp smaller voltage swings of 1 or 2 V would be more noticeable.
 
thegame said:
When playing master volume high gain amps I start noticing a difference when the voltage drifts +/- 3 V. Any less and I don't notice. I'm thinking with a cranked plexi type of amp smaller voltage swings of 1 or 2 V would be more noticeable.
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Same here. I strive to get 113 volts. It fluctuates at time to 112-114. Anything more and I notice it. Of course there are times I will bring the voltage up for some tighter sounds. There have been some low wall voltage times where I’m able to get it down to 100v.
 
I use a Furman voltage regulator/conditioner that's allegedly 120vac out but per my meter it is closer to 119vac. That works for most of my amps and I use a variac on my Superlead.

But my homebrew Superbass-now-JEL mod is ~440vdc B+ when plugged into the Furman and ~460vdc B+ when plugged into the wall. So that amp gets biased and played at ~124vac wall voltage. Just sounds better to me.

Some amps won't sound better at lowered voltages. Some might like the high wall voltage. So I guess the take-home is to monitor it and listen.
 
House current is nasty, noisy, dirty stuff. Variac to control the front, Rock Crusher to control the back. It is surprising it is so simple.
 
I need to break down and check out one of those brown boxes or a variac. I have a Furman Voltage regular, which has been helpful, but they’re flawed too. Depending on the incoming voltage and what tap the Furman utilizes, it can actually increase the voltage. Just yesterday it was reading 123, but the Furman was actually putting out 125.
 
glpg80 said:
If you’re using a Bogner XTC and have the class A/AB switch, if you’re anything over 115V into the amp you’ll redplate the EL34s in class A. The high B+ doesn’t give much wiggle room to variances of wall voltage into the amp.
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Redplating sounds good.
 
glpg80 said:
God this amp feels amazing. Wait why are my lights flickering 🤔😂
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I have a set of tubes for my high cathode bias amp that red plate just for taking passes when recording. The colder set is for gigs/rehearsals. Nothing blooms like tubes that are dying.
 
messenger said:
How does the brown box differ from a Variac (which seems much lower priced)
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Both can accomplish the same thing but a variac can turn voltage up or down, will offer finer control over the specific voltage, but will also be larger and heavier. You’ll also need a multimeter to set the voltage if it doesn’t have an (accurate) digital display.

The brown box will be using a smaller and lighter multi tap transformer that will place various taps out of phase with the line voltage (depending on the knob settings) which will subtract that voltage from the line voltage. Also no danger of someone walking up and turning the big knob up, giving your amp way more voltage than it wants.

Be careful of the cheap Chinese widow maker variacs on Amazon and eBay, I’ve seen quite a few reviews where they are wired wrong and dangerous to use right out of the box.
 
fearhk213 said:
I need to break down and check out one of those brown boxes or a variac. I have a Furman Voltage regular, which has been helpful, but they’re flawed too. Depending on the incoming voltage and what tap the Furman utilizes, it can actually increase the voltage. Just yesterday it was reading 123, but the Furman was actually putting out 125.
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That doesn't sound like it's working correctly. It isn't regulating the voltage. Mine always reads 119.2vdc but my wall voltage spans 122vac-126vac.
 
SpiderWars said:
That doesn't sound like it's working correctly. It isn't regulating the voltage. Mine always reads 119.2vdc but my wall voltage spans 122vac-126vac.
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That's how it functions. It's supposed to provide a constant 120v +/- 5v. It will shift to the tap that gets closest based on the incoming voltage. Oddly, that sometimes results in a slightly higher voltage. I've heard of others experiencing the same thing as well. I used to have the breakdown of what the incoming voltage ranges are for each tap and the voltage each tap would provide. All I could find in the online manual is an example that says incoming voltage of 92v would result in 110v, so beyond a certain range up or down it can't get within +/-5v of 120v either. That's totally understandable, though. Overall, it's probably not that much of an issue with modern amps. With older amps where 120v may already be borderline, it could be problematic.
 
fearhk213 said:
That's how it functions. It's supposed to provide a constant 120v +/- 5v. It will shift to the tap that gets closest based on the incoming voltage. Oddly, that sometimes results in a slightly higher voltage. I've heard of others experiencing the same thing as well. I used to have the breakdown of what the incoming voltage ranges are for each tap and the voltage each tap would provide. All I could find in the online manual is an example that says incoming voltage of 92v would result in 110v, so beyond a certain range up or down it can't get within +/-5v of 120v either. That's totally understandable, though. Overall, it's probably not that much of an issue with modern amps. With older amps where 120v may already be borderline, it could be problematic.
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OK, mine is a really constant 119.2vac (I'm constantly futzing with amps and always measure the AC in) so it seemed off. Still seems off frankly but if you say that's the way that model works I believe you.
 
This thread motivated me to finish building my diy bucking transformer. I used a 20 volt Center tapped transformer so I can do -10 volts or -20 volts. Follows same scheme that Rob Robinette has on his website.

EB8A4850-C10C-4D9E-86DC-E6B1A9D20EF7.jpeg

ACF0ED95-2E49-4CEF-82FD-58892BFB14E4.jpeg

The volt meters both read low by 4 volts, annoyingly. So in the picture my line voltage was 249 and the output was 226. Going into a 230v amp.

In retrospect a 16 volt ct transformer might have been a better choice to get closer to 230 and 240 on each setting, maybe I’ll change it since a new transformer is only about £15.
 
OMG! Thanks a lot! Now I’m going to be wondering how the voltage coming from my wall plug is messing with my tone. One more thing to obsess about! 😆
 
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