I wanted to start a thread to see people's solutions to dealing with tube amps designed to work on other than modern line voltages in your country. I've run into the issue with made in China amps with 110V wound primary transformers, and the issue this causes. I'm sure there is some vintage gear that shares this problem.
The only commercial product I've seen, that is reasonable priced, that can address this is the APC Line-R 1200 and it has options for 127-120-110. Has anyone seen another commercially available 120-110V converter/device? I'm personally using a bucking transformer, but this is more of a DIY solution as far as I know.
I uploaded a video today about this and would welcome input on other solutions I may have missed.
Monday Monologue: Made in China Tube Amps and 110V or 220V Bucking Transformers - YouTube
The only commercial product I've seen, that is reasonable priced, that can address this is the APC Line-R 1200 and it has options for 127-120-110. Has anyone seen another commercially available 120-110V converter/device? I'm personally using a bucking transformer, but this is more of a DIY solution as far as I know.
I uploaded a video today about this and would welcome input on other solutions I may have missed.
Monday Monologue: Made in China Tube Amps and 110V or 220V Bucking Transformers - YouTube
Seconded. A bucking transformer works great. I built a box with switched power for 3 outlets (2 bucked, 1 line), which lets me switch a bass amp and 1or 2 power amps with one switch.
I too vote for bucking transformers.
No switching noise, no nonsense, efficient because the secondary voltage of the buck/boost is small, just the difference from the power mains voltage versus the amplifier voltage spec.
And, the secondary voltage times the secondary current of a buck/boost, is much lower than a full transformer that has a required ratio, such as 110:120 for a 110V amp, and 120V power mains.
Lighter, cooler, smaller. What is not to like?
No switching noise, no nonsense, efficient because the secondary voltage of the buck/boost is small, just the difference from the power mains voltage versus the amplifier voltage spec.
And, the secondary voltage times the secondary current of a buck/boost, is much lower than a full transformer that has a required ratio, such as 110:120 for a 110V amp, and 120V power mains.
Lighter, cooler, smaller. What is not to like?
If you really want to go all out then use a variac. Invaluable as a troubleshooting tool as well.
Does anyone know of a commercially available 120-110 bucking transformer setup? I made my own, but people wanting to use these made in China amps with 110V primary transformers in the US don't all feel comfortable building a DIY solution.
The APC line-R 1200 is the only reasonably priced solution I've found at ~$60. One of those $5000 PS audio regenerators doesn't make sense for a $500 ChiFi amp 😛
The APC line-R 1200 is the only reasonably priced solution I've found at ~$60. One of those $5000 PS audio regenerators doesn't make sense for a $500 ChiFi amp 😛
I got lucky and found an isolation tx that has a switch to adjust for incoming voltage to 120 out. Two birds with one stone, isolation and compensation! It’s a vintage unnamed unit from the 60’s. You might get lucky and find one too on the bay.
There are a couple of Viz Isotap transformers up for bid right now. I’d rather have an actual tax than a poorly reshaped electronic sine wave converter.
Do you really want to be running tube gear on an isolation transformer ungrounded?
This may not apply to many, but my line voltage can vary substantially by time of day, day of week, or season of the year. I've seen as low as 119 and as high as 129, over sometimes short intervals (midday one day compared to midnight only a few days later). Don't assume yours varies that substantially... but don't assume that it doesn't. I've decided on a variac with digital readout for my most valued vacuum tube gear. Spin it to the right setting whenever and however needed.
Mine will vary 125V to 104V minute by minute. On Laundry Day. As the washer, well pump, water heater, and dryer do their dance. (Solid 125V at the street, but I'm 500 feet from the pole on #2 Al wire.)
Stephe's APC may be a wonderful find. I'm gonna re-post over at the old guitar amp room, for guys from the early 1950s.
However, I have owned such a thing and it *switched*. It was a many-tap autotransformer with a bunch of 7V taps. A bunch of triacs selected an optimum tap. At work they had a far bigger gizmo but with mechanical switching. When these things switch it can be quite a "pop" in the system (or not, depending on filtering and grounds).
Loud guitar with a drummer, 7V line jumps may not be noticed. Hi-Fi might. Ah, but it's only 60 bucks.
By the time you buy a transformer, build a box, meter, outlets, etc. you'll spend more money and waste more time than doing the right thing. And it's not adjustable.
https://www.amazon.com/2000VA-Varia...child=1&keywords=variac&qid=1625546483&sr=8-8
Quit trying to re-invent the square wheel 🙂
https://www.amazon.com/2000VA-Varia...child=1&keywords=variac&qid=1625546483&sr=8-8
Quit trying to re-invent the square wheel 🙂
PRR,
My house was built in 1978.
The mains power, day, night, noon, summer, winter, spring, fall, etc. varies from 117V to 123V.
120V, +/- 2.5%
And 4 houses are powered from the same mains transformer. All 4 houses use electric: heat, washer, dryer, water heater, stove, refrigerator, air conditioners . . .
and my un-regulated vacuum tube amplifiers.
Lucky me (no, blessed me).
Your power varies from 125V to 104V?
114.5V +/- 9% or 10% . . . Wow!
Either your house needs to be re-wired, Or your electric company needs to be fired.
Or get the house and rollers, and roll it out closer to the street (cheaper than 500 feet of #2 pure gold wire).
How about High Voltage to a pole next to the house, and a mains transformer on the pole?
Just my opinion
My house was built in 1978.
The mains power, day, night, noon, summer, winter, spring, fall, etc. varies from 117V to 123V.
120V, +/- 2.5%
And 4 houses are powered from the same mains transformer. All 4 houses use electric: heat, washer, dryer, water heater, stove, refrigerator, air conditioners . . .
and my un-regulated vacuum tube amplifiers.
Lucky me (no, blessed me).
Your power varies from 125V to 104V?
114.5V +/- 9% or 10% . . . Wow!
Either your house needs to be re-wired, Or your electric company needs to be fired.
Or get the house and rollers, and roll it out closer to the street (cheaper than 500 feet of #2 pure gold wire).
How about High Voltage to a pole next to the house, and a mains transformer on the pole?
Just my opinion
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Another interesting solution is a ferroresonant power supply (transformer). It has its own issues, but can be a good solution depending on your specific situation.
Those have both regulation and filtering. There is good pricing on used transformers:
Transformers - Constant Voltage
Transformers - Constant Voltage
This is a good question and I am certain that someone will correct me if I am wrong.
The isolation transformer is only connected to hot and neutral in the USA. So the ground connection would be direct; e.g. "around" the transformer.