18Watt.com

Hi all at 18watt,
Maybe you made the same experience:
You play and enjoy your tone. Your tone couldn't be better. On the other day you start to play, but what happened? Although you changed nothing, now the sound is much different than the day before. The tone is kind of harsh, sterile or unmusical. This happened so many times to me and sometimes I believe, it's me and not the amp. But it's not my ears or mood, it should be the change in voltages. In my place it changes between 220 and 240 V. But I never measured the voltages when my sound was great, only enjoyed playing
I got a manual voltage regulator and I try to get my heating voltages to exactly 6.3 V. But it seems to me that gives not the sweet spot in sound.
What's your experience?
I don't have the money, to afford me a power conditioner like the pros. Is there a simpler way?

Thanks a lot
musicheals

The sweet spot is typically based on B+ voltage, not the heater voltage.

you can get a variac with a voltage meter on it, then you will be able to manually keep your source voltage consistent.

Thanks,
Josh

I used Rob Robinettes site to build a Bucking transformer. it supplies 117VAC and 112VAC or thereabouts
https://robrobinette.com/5e3_Modificati ... ransformer

Thanks a lot! Very interesting!

lavrgs wrote: ↑

Tue 06/01/21 11:51 pm

I used Rob Robinettes site to build a Bucking transformer. it supplies 117VAC and 112VAC or thereabouts
https://robrobinette.com/5e3_Modificati ... ransformer

Thanks for posting that link. I've been intending to build one myself, probably using a 10VCT transformer. Incidentally, this issue isn't only about tone. Wall voltages at my location often exceed 125V during the day. That pushes B+ to nearly +500V in some larger hi-fi amps. Sooner or later, the smoke's gonna get out of those caps.

Here's another site with good info on bucking transformers.

https://sound-au.com/articles/buck-xfmr.htm

Jack

Some people were concerned that my heater voltage would be too low but this brought them to be right on target

Higher heater voltages will shorten tube live. But what about lower voltage? Opinions differ at this point it seems. Will it be dangerous for my tubes if I find out, my amp is best sounding with only 5V?

The valves will first be intermittent then as you go lower just stop working at some voltage lower than the designed heater voltage. What point that happens depends on the type and manufacturer or even the individual valve.
It will never be any benefit to your tone because the heaters only provide the circumstances for the valve to operate (or not).

Dd