VARIAC use with trainwreck style amp......

[redshark]

Everytime I read my house power on the wall is always 123-126 VAC.

I wish I had 120 all the time but the only way to achieve that is using a VARIAC.....

I see a lot of those devices on ebay....what are the specs I need to pay attention to if I decide to buy one so my amps always have steady 120VAC?

Just curious!!!!

[katopan]

I wish I had 120 all the time but the only way to achieve that is using a VARIAC.....

Not the only way....
http://www.geofex.com/article_folders/v ... ntvolt.htm

You can make it switchable with different taps, build in a cheap $10 multimeter to display output volts, etc. Cheaper and lighter to carry around than a variac.

[redshark]

Thanks!! I will look it up!!!

[RJ Guitars]

Not all 120 volt AC supplies are created equal... http://www.merrenaudio.com/power_quality
As Chris Merrin points out, it gets messy and you might not get the same B+ DC voltage with 120 AC at your house as I would at mine.

I've come to recognize that my best sounding amps tend to still be my best sounding amps with the local voltage swings and I've never been able to tell by the sound of the amp whether the voltage is high or low.

I think it is pretty universally accepted that the average AC voltage is higher now than it was 30 or 40 years ago so it does make me wonder if those original Wreck amps sound exactly the same now as they did then? Is "Reality Check" gonna sound the same in Louisiana as it did in Ken Fischer's basement?

If you buy one of those power stabilizer units I'll be curious what your ears tell you... it might be an interesting study.

[redshark]

I think there will be some impact with tone. If I get plate voltage in my express of around 410vdc with the average 125vac from the wall if I can have 120 I expect it to drop aprox 15 volts dc on the plates getting a plate voltage of around 395vdc. Subtle difference but it can be heard for sure. My rocket will benefit too.

[redshark]

I just saw a device called "brown box" which I didn't know about, that decreases wall voltage. Kinda pricey but is variable adjustment. Like a light variac. It sells for 325!!

looks very interesting!!!

[geetarpicker]

I have a variac but I recently picked up a "Brown Box". It is pricey for what it is but it is very well built and works well. As far as I can tell it's a bucking transformer, but it also has several input taps and reduces the voltage to more than the typical -6 or -12v that most bucking/filament transformers net and has a bunch of output taps by rotary switches. It gives a range of voltage from about unity (around here about 125v) down to about 105v. It also has a lit digital meter with voltage and current. It basically has 4 input voltage settings (120,122,124,126) then 4 output settings of -3%,-4%, -6%, -10%. Somewhat convoluted but you can net quite a range of voltages using the two rotary selectors. I do like the fact that it cannot boost the voltage above unity, one of the reasons I get nervous with a variac on a gig if someone bumps it. Also the Brown Box is less bulky and considerably lighter than most variacs for sure, and I like having the digital read out built in. It also has a circuit breaker and power switch. I haven't tried it yet with any of my guitar amps though, but it's been powering my tube McIntosh stereo nicely which is happier down at about 110-115v.

[lpd]

I have a variac but I recently picked up a "Brown Box". It is pricey for what it is but it is very well built and works well. As far as I can tell it's a bucking transformer, but it also has several input taps and reduces the voltage to more than the typical -6 or -12v that most bucking/filament transformers net and has a bunch of output taps by rotary switches. It gives a range of voltage from about unity (around here about 125v) down to about 105v. It also has a lit digital meter with voltage and current. It basically has 4 input voltage settings (120,122,124,126) then 4 output settings of -3%,-4%, -6%, -10%. Somewhat convoluted but you can net quite a range of voltages using the two rotary selectors. I do like the fact that it cannot boost the voltage above unity, one of the reasons I get nervous with a variac on a gig if someone bumps it. Also the Brown Box is less bulky and considerably lighter than most variacs for sure, and I like having the digital read out built in. It also has a circuit breaker and power switch. I haven't tried it yet with any of my guitar amps though, but it's been powering my tube McIntosh stereo nicely which is happier down at about 110-115v.

I've tried variacs, iso taps, iso transfos, ect on hifi and have always found the output to suffer. Unless the power source has current headroom the music to my ears appears compressed. I haven't noticed as much of a difference on guitar amps, but they also operate on less current than hifi gear does.

[geetarpicker]

Well my McIntosh MC225 is only 25-30 watts per channel so it simply doesn't draw that much current. That said, my MX110 tuner preamp (like most of them) runs pretty hot as they really undersized the PTs on those. I think running it a little lower voltage wise is cheap insurance.

[lpd]

Well my McIntosh MC225 is only 25-30 watts per channel so it simply doesn't draw that much current. That said, my MX110 tuner preamp (like most of them) runs pretty hot as they really undersized the PTs on those. I think running it a little lower voltage wise is cheap insurance.

I've noticed the tube stuff sounds ok with variacs ect. but I tried a super expensive voltage stabilizer on a solid state FM Acoustics amp and had horrible results. Maybe tubes are more forgiving