# Voltage regulator : Tone Preserver



## GuyB

I have a voltage problem at a place where I jam : the voltage is unstable and often too high (was tested once at 128v, witch is too high for my Traynor YCV 50 and my Mesa Mini Rec).

I've heard, and have read a good review, about the Tone Preserver from Vintage Sound Workbench. It reduces by -6 or -12v the incoming voltage, and it is small and not too pricey. Does somebody knows something about it ? Mainly, I would like to know if it reduces the voltage below 120v if the voltage coming in is already at 120 and the Tone Preserver is set at -6v or -12v.


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## jb welder

It is more of a voltage reducer than regulator. It will take the set reduction amount off the incoming voltage. So if it is set for 6, it will take away 6 volts no matter what the incoming voltage is. 118V will be reduced to 112, 130V will be reduced to 124. It uses a "bucking coil" to knock down the voltage. It's output is limited to 4amps current.
I thought it a bit expensive, but I guess thats just me!
For DIY plans or further info on how they work, see this: Vintage Voltage Adapter


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## GuyB

Thanks. I was afraid it was that ! This means that if the voltage is at 120v and the reducer is at -6v, the amp will run at 114 which is less a worry than an over voltage but is not quite good for tube amps either. I saw something made by Furman with seems to be a real regulator but THIS is really pricey (around a thousand bucks and more !!!). Do you know of something else to regulate (stabilize) the voltage at 120 ?


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## greco

*Deleted...not good advice


*


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## loudtubeamps

Sounds like you need a line filter which filters and regulates the mains voltage.
You might want to save your money and get the owner of the jam space to hire an electrician to find out what's going on with the power fluctuations or call Hydro Quebec.


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## Jim DaddyO

greco said:


> You could look into getting a Variac.
> 
> *3PN1010B Variac Variable Transformer, 120V Input, 0-140VAC Output 10 Amps, Portable Model with Case, Cord, Receptacle, Fuse and Switch*
> 
> 
> View Larger Image​*Price:* $361.00
> 
> *Item Number:* *ST3PN1010B*
> Quantity:
> Email this page to a friend*
> In Stock For Same Day Shipment
> We will advise immediately if your order will be delayed​
> Manually Operated P/NInputVoltsPhaseHertz *OutputVoltsConstant
> Current
> Rating3PN1010B1201 PH50/600-14010A
>  
> 
> However, as the article says, don't let anyone else touch it !!
> 
> Cheers
> 
> Dave* 



I believe a variac lifts the ground so it may not be a good idea use one so casually.


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## loudtubeamps

Power Conditioners at zZounds


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## loudtubeamps

Jim DaddyO said:


> I believe a variac lifts the ground so it may not be a good idea use one so casually.


http://instrumentation-central.com/staco/EngineeringDrawings/3PN501B.pdf


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## greco

Jim DaddyO said:


> I believe a variac lifts the ground so it may not be a good idea use one so casually.


Thanks for the advice. I wasn't aware of that.

Cheers

Dave


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## nonreverb

Variacs are not isolated. Input and output have common ground.
I'd go with the power conditioner myself. It will keep the voltage constant regardless of the source.


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## GuyB

Thanks for all the good infos. I'll check into that.


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## Jim DaddyO

nonreverb said:


> Variacs are not isolated. Input and output have common ground.
> I'd go with the power conditioner myself. It will keep the voltage constant regardless of the source.


Thanks for clearing that up. I was not 100% sure.


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## loudtubeamps

Originally Posted by *Jim DaddyO* 
I believe a variac lifts the ground so it may not be a good idea use one so casually.



http://instrumentation-central.com/s...gs/3PN501B.pdf​






guess I should have put a description here re:basic schematic for VariAC
cheers, d


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## GuyB

I just looked at the Furman as told by loudtubeamps : looks like the AR1215 model might do the trick (but it's around 500 $ !). Might ask for a birthday gift !

About the variac, could you please explain what "input and output have common ground" (nonreverb) and "a variac lifts the ground" (Jim Daddy) means ? Will it make noise problems and/or could it be dangerous ?


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## jb welder

Just to nitpick a little about the terminology, you are talking about a regulator, not a conditioner. Conditioners protect from spikes and line noise but can't alter the line voltage. They are not very expensive. 
Power regulators are very expensive and maintain a constant voltage output, no matter what the line voltage does (within the limits of the specs).
The variac will not maintain a constant output voltage. It will boost or cut whatever you set the dial for. The output voltage will go up and down if the line voltage goes up or down. In that way it is similar to the tone preserver.
The variac does not lift the ground. The 3rd prong safety ground is independant of the adjustable part. Lifting ground is no longer legal in Canada or the US. As far as I know, you can't even buy the "cheater" plugs anymore (3 prong to 2 prong adapter).
Lifting grounds is just too dangerous, so it is outlawed.


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## greco

jb welder said:


> *The variac will not maintain a constant output voltage*. It will boost or cut whatever you set the dial for. The output voltage will go up and down if the line voltage goes up or down. In that way it is similar to the tone preserver.


Thanks for this information. I wondered if that was the case.

Cheers

Dave


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## ampaholic

GuyB said:


> I've heard, and have read a good review, about the Tone Preserver from Vintage Sound Workbench.


It's actually called an Amp Preserver and I've owned one now for a couple of years. Some might consider them pricey but they are reliable and built like a tank.
I'm a vintage amp addict and struggled with a couple of my vintage Fender's (especially a Deluxe Reverb) to get internal voltages under control, power tube plate voltage in particular. Trying different rectifier tubes can help this but I like the thought of running my amps as they were intended to run in the 50's and 60's. Problem is the line voltage around here is 123 VAC and that little bit of extra juice at the plug is magnified considerably once converted to DC. I'm sure some would argue that running a valuable tweed amp designed to operate at 110 VAC won't be hurt a bit at 123 volts but I sure feel better running my blackface amps at 117 Volts (-6 setting) and tweed at 111 volts (-12 setting).
Now I get voltages that are nearly identical to what you see on those old schematics plus wear and tear on the amp has to be lessened. And maybe I'm just trying to convince myself but I think the amps all sound better!
I own a variac too but I don't like the potential of accidentally cranking up the voltage.
The only downside is that once you've biased the amp using the Amp Preserver you have to use it all the time afterward (at least with fixed bias amps).


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## GuyB

Thanks a lot to all of you.


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## nonreverb

Indeed, a regulator it is! Typing before I think...oh well ;P
Actually, when you look at what a Variac or one of it's offshoots cost, a regulator or at least a conditioner is a reasonable investment and is an excellent piece of equipment for a gigging musician. I have repaired more than one amp subjected to venue(bar) AC supply over the years and it ain't pretty. Particularly solid state stuff.
I use regulators in my Hammond organ rental units as generators are notoriously bad a regulating both voltage and frequency and frequency is integral to a Hammond's pitch.



jb welder said:


> Just to nitpick a little about the terminology, you are talking about a regulator, not a conditioner. Conditioners protect from spikes and line noise but can't alter the line voltage. They are not very expensive.
> Power regulators are very expensive and maintain a constant voltage output, no matter what the line voltage does (within the limits of the specs).
> The variac will not maintain a constant output voltage. It will boost or cut whatever you set the dial for. The output voltage will go up and down if the line voltage goes up or down. In that way it is similar to the tone preserver.
> The variac does not lift the ground. The 3rd prong safety ground is independant of the adjustable part. Lifting ground is no longer legal in Canada or the US. As far as I know, you can't even buy the "cheater" plugs anymore (3 prong to 2 prong adapter).
> Lifting grounds is just too dangerous, so it is outlawed.


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## Wild Bill

For a cheap and dirty solution, I'd head out to the nearest computer store! NOT a big box store like Future Shop, where they sell computers like selling a toaster, but one of those much smaller chains that sells all the plug in boards and stuff. Ask them for a UPS, or Uninterruptable Power Supply.

These are basically a battery charger keeping a battery charged up, which then feeds an inverter to give 120 volts to the computer. The idea is dual purpose. You have complete isolation from the mains, so no noise or spikes get through the battery and inverter into the load, which doesn't have to be a computer. If the power fails, you have 5 or 10 minutes or more of backup power from the battery, depending on its size. For a computer, that means time to shut it down so you don't lose anything.

You don't care about the power loss protection. You just want to have a regulated 120 volt source to your amp. Make sure the UPS you buy is beefy enough to supply your amp without getting overloaded. Easy rule of thumb is to multiply 120 volts by the current rating of your amp's fuse, then round up to the nearest rating of the UPS. So if your amp has a 2 amp fuse you figure 2 x 120 = 240 watts. You would buy a 300 watt unit. Don't go plugging extra stuff into it to overload it. The inverter will just overheat and shut down.

Since these are a mass-produced, volume device for the computer world they should be the best bang for your buck.

Wild Bill/Busen Amps


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## GuyB

Many thanks Wild Bill, very interesting, I will look into that seriously. The rating of my Mesa Mini Rectifier is 1 (1 x 120 = 120) and the one of my Traynor YCS 50 is 1.6 (1.6 x 120 =192) so what do suggest for both of them ?

And just to be sure that I understand : if the voltage is almost stable at, let's say, 130v, the UPS will give my amp a constant 120v. And what happens if the voltage varies, let's say that it goes around between 116 and 130, what will the UPS do ?


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## epis

Unfortunately, this idea with UPS isn't gonna work. Anyway, running from backup battery it will provide stable 120V/60Hz, but there is no voltage stabilization at regular operation, running from the mains.


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## loudtubeamps

*epis* 
"Unfortunately, this idea with UPS isn't gonna work. Anyway, running from backup battery it will provide stable 120V/60Hz, but there is no voltage stabilization at regular operation, running from the main"


APC Back-UPS ES 550VA w/ 8 Outlet at Memory Express
This model claims : *Power conditioning *
Protects connected loads from surges, spikes, lightning, and other power disturbances.

The battery backup isn't really the issue here , it's the surge protection and filtering, is it not?


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## epis

This is first GuyB's sentence : "I have a voltage problem at a place where I jam : the voltage is unstable and often too high (was tested once at 128v, witch is too high for my Traynor YCV 50 and my Mesa Mini Rec)."
So it's NOT about surge protection, and what does it have with my feedback score ? Cheers, Damir


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## bluzfish

With UPS, the equipment is always running off the battery which is always isolated from the mains so the voltage remains constant no matter what happens on the mains side of the transformer. The only question is how much mains variation can the system tolerate and for how long. Some UPS systems for larger scale computer systems can be as large as a refrigerator (or larger in some military installations I've seen) to accomodate a larger battery/transformer/charging system that can tolerate potentially wild mains spikes and voltage variations. Or they can be as small as a lunchbox for occasional moderate spikes and voltage variations required for an individual workstation and peripherals. The only question is, what will be the draw on the battery and how extreme are the power variations in the mains.


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## nonreverb

I think the quick and easy answer would be know exactly what your requirements are and check the specs before you buy. I suspect a good UPS will be able to handle the problem GuyB describes....or there's always voltage regulator$


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## epis

Excuse my ignorance .


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## bluzfish

epis said:


> Excuse my ignorance, my answer was based on practical experiance with some older models witch had relays in output, like this one :
> 
> http://atmega32-avr.com/UPS_Schematic_Circuit_Diagram.gif


I can see from the schematic that the circuit does indeed run off the mains with the voltage regulated until the circuit detects a major variation or spike at which time the relays switch the power draw to the battery. I can't tell with a cursory examination if the power switches back to the mains when the anomoly has passed but I imagine that would be a logical function. However, in more sophisticated systems, the power is constantly drawn from the battery to eliminate the possibility of the relay not being able to react quickly enough. This circuit would be quite adequate for mechanical devices and such, but for sensitive electronics, may not be enough protection.


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## GuyB

Wow ! I really appreciate the interest you guys put in this question and I thank you all for your contribution. But... I am an absolute ignorant on these electrical things and I don't know now what to do ! Is the UPS still an answer for me ? (I checked the retail price of a Furman voltage regulator and it is at 700 $... another "wow" !)


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## loudtubeamps

epis said:


> This is first GuyB's sentence : "I have a voltage problem at a place where I jam : the voltage is unstable and often too high (was tested once at 128v, witch is too high for my Traynor YCV 50 and my Mesa Mini Rec)."
> So it's NOT about surge protection, and what does it have with my feedback score ? Cheers, Damir


Sorry epis. I did a "reply with quote" and somehow "feedback score" got in there.
I will edit that out. cheers, d.


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## loudtubeamps

bluzfish said:


> With UPS, the equipment is always running off the battery which is always isolated from the mains so the voltage remains constant no matter what happens on the mains side of the transformer. The only question is how much mains variation can the system tolerate and for how long. Some UPS systems for larger scale computer systems can be as large as a refrigerator (or larger in some military installations I've seen) to accomodate a larger battery/transformer/charging system that can tolerate potentially wild mains spikes and voltage variations. Or they can be as small as a lunchbox for occasional moderate spikes and voltage variations required for an individual workstation and peripherals. The only question is, what will be the draw on the battery and how extreme are the power variations in the mains.



That's new information for me.
I thought the backup battery was always in a charge/ready mode while the mains were on.
During a power interruption, I assumed , wrongly it seems,that a relay switched the battery into the inverter supply chain for temporary use and the powering down safely of pooters and such.
cheers, d


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## bluzfish

There are different types of UPS that serve different purposes. As I mentioned earlier, there are systems that use the method you are referring to. As far as I know, those types of switching UPS are used for less sensitive equipment that can take some of the potential voltage variation and spike hits before the relay has a chance to react. Relays and other protection circuitry are relatively slow compared to the instant of attack in a voltage spike for example. In sensitive computer systems of the type used in banks, governments, finanacial institutions and military, the damage can occur before any other circuitry has a chance to sense the spike or fluctuation and jump into action. Hence the UPS that never allows the protected equipment to ever see direct mains power. These are the UPS systems I am most familiar with. But I am most certainly not the alpha and omega of information about different types of UPS and how they are used. My input is based on what I know from my education and experience in large scale computer systems. There is much that I don't know.


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## nonreverb

There's plenty of info there for anyone to make an informed decision 



bluzfish said:


> There are different types of UPS that serve different purposes. As I mentioned earlier, there are systems that use the method you are referring to. As far as I know, those types of switching UPS are used for less sensitive equipment that can take some of the potential voltage variation and spike hits before the relay has a chance to react. Relays and other protection circuitry are relatively slow compared to the instant of attack in a voltage spike for example. In sensitive computer systems of the type used in banks, governments, finanacial institutions and military, the damage can occur before any other circuitry has a chance to sense the spike or fluctuation and jump into action. Hence the UPS that never allows the protected equipment to ever see direct mains power. These are the UPS systems I am most familiar with. But I am most certainly not the alpha and omega of information about different types of UPS and how they are used. My input is based on what I know from my education and experience in large scale computer systems. There is much that I don't know.


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## loudtubeamps

bluzfish..........thanks for the added info on the UPS units.
cheers, d.


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## bluzfish

I'm glad I had a chance to correct my original statement that with UPS, equipment is* always *running off the battery. That is obviously not true. That is just the type of UPS I was thinking of at that moment. I would imagine a switching type UPS might indeed be useful with tube equipment that already does some power conditioning itself. With the additional voltage taming in a UPS like the one in the schematic that epis posted might be sufficient and much more cost effective. Of course the unit in the actual schematic would be an enormous overkill in his situation. I think a rating determined by something more like Wild Bill's calculation would be a good formula to use as a guideline.


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## GuyB

Again, thanks all of you. But as I said I am a complete ignorant (and English is not my primary language) in these matters even if I can understand that there is enough information in this thread to make a choice. I understand that there are UPS that will always give a constant 120v to my amp and others that don't. I see also that I have to use the rating (in watts) as suggested by Wild Bill. I don't want either something that would be to heavy to carry around. Now, would somebody be kind enough to tell me what kind of UPS I would ask in a store, or the name of a model. Again, many thanks in advance.


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## jb welder

Regulation is again the key word for your purposes. One of the UPS's I came across had an output voltage spec. of 120V +/- 5%. I don't think this would work for you as it would allow up to 126V. I believe our line voltage spec. is 5%, so it is the same as what comes out of the wall outlet. 
So you want to be checking the output voltage spec., looking for something with a regulated output, probably within 1 or 2 % of 120V. 
Unfortunately, I'm not sure such a unit will suit your weight or budget restrictions.


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## loudtubeamps

I just keep wondering what is causing a steady state of the high voltage that you are reading?
What's the average in your area, say in your own home?
Does anone else "on the grid" experience 128 V.A.C.?


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## GuyB

loudtubeamps said:


> I just keep wondering what is causing a steady state of the high voltage that you are reading?
> What's the average in your area, say in your own home?
> Does anone else "on the grid" experience 128 V.A.C.?


It's in an old barn that has been "restored" and I think that the owner made the electricity by himself (and he's not an electrician !). I'm the only one with a tube amp and the only with problems. I think that it's a problem with this place; at home everything is perfect.

I am know gathering infos from different stores about the UPS (I didn't have a price yet). If it does not fill my needs I will look back at the Furman, there is a possibility that I can have one at a much better price.

Thanks again all of you for all the good infos that put me on the right track for my research.


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## GuyB

Well, I just returned back from an Apple store where I met a tech guy (an electrician) who knows about the UPS.


The one they sell at 260 $ does not meet my needs. It does regulate the voltage but in a range that exceeds the need of my amps. The upper limit of voltage after witch it starts to "regulate" is 136v when the need for my amps should not be more than 126v (5% tolerance from 120v by Mesa's indications). They do have a model that would suit my needs but it's at 900$ !


So I would be better with the Furman, if I can find a good deal and after making some verifications at the place (recheck the voltage, the ground - the Furman doesn't work if the ground is not o.k. - etc.).


Thanks a lot to you guys, you have been a big part helping me understand all this thing and putting me on the good track.


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## amp boy

Why not get a Variac ?

$50 - 100 bucks.


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## pipestone62

Been searching for an alternative to Variac or Brown Box and thanks to this site found the Amp Maniac on Vintage Sound Workbench. It’s my Xmas present to myself, been wanting to get a voltage regulator for a long time to run my old amps at 110 volt. Talked to the guy on the phone who builds them, looking forward to getting it soon.


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## Latole

Power conditionner won't reduce voltage. 
Variac is the tool you need.

Why do you think 128 volts is too high for your amp ? 
Where information come from ? 

How many people with electronics gear are used in this area with 128 volts ?


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## player99

Will this one work?








YaeCCC 5 Amp Variable Auto Transformer, AC Variable Automatic Voltage Regulator Converter(500W) : Amazon.ca: Tools & Home Improvement


YaeCCC 5 Amp Variable Auto Transformer, AC Variable Automatic Voltage Regulator Converter(500W) : Amazon.ca: Tools & Home Improvement



www.amazon.ca





The EVH Variac story:


The TRUE Story of Eddie VanHalen Using A Variac With A Tube Guitar Amp | Warehouse Guitar Speakers



Does running a 30 watt tube amp at say 90v stress any components?


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## Latole

Running tube amps at low voltage mean all tubes 's heater don't properly heat tubes. 
And IMO it is not very good.
if you can keep tubes's heater at 6. 3 volts, you can drive the amp at any low voltage to the amp. 


That is what Kevin O'Connor 's London Power scaling do 









Power Scaling for Tube Amplifiers Q&A - London Power Tube Amps & Kits


Power Scaling for tube guitar amplifiers - a technology by London Power. Get your amplifier's ultimate tone, as quietly as you like!




londonpower.com


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## player99

Latole said:


> Running tube amps at low voltage mean all tubes 's heater don't properly heat tubes.
> And IMO it is not very good.
> if you can keep tubes's heater at 6. 3 volts, you can drive the amp at any low voltage to the amp.
> 
> 
> That is what Kevin O'Connor 's London Power scaling do
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Power Scaling for Tube Amplifiers Q&A - London Power Tube Amps & Kits
> 
> 
> Power Scaling for tube guitar amplifiers - a technology by London Power. Get your amplifier's ultimate tone, as quietly as you like!
> 
> 
> 
> 
> londonpower.com


Is it just hard on the tubes?


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## Latole

player99 said:


> Is it just hard on the tubes?



Yes,
All other components ( resistors and capacitors ) like low voltage


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## nonreverb

Here's something....this is a regulator which is a better option than a conditioner. There are a myriad of different models...this is an example.








Norstar Power Converter with Voltage Stabilizer (5000 Watts) - Step Up & Step Down Voltage Transformer - Automatic Voltage Regulator with Stabilizer (5000 Watts) : Amazon.ca: Electronics


Norstar Power Converter with Voltage Stabilizer (5000 Watts) - Step Up & Step Down Voltage Transformer - Automatic Voltage Regulator with Stabilizer (5000 Watts) : Amazon.ca: Electronics



www.amazon.ca


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## jb welder

Running heaters higher than 6.3V is much harder on the tubes than running them at lower than 6.3V.
Also, modern line voltage can stress the filter caps if they were running near their voltage rating at old line voltages.
Lots of guys put bucking transformers in their vintage amps or radios to drop the line voltage down by 6 or 12V before it hits the power transformer.
I have a feeling that's what this product may be, but I'm not sure. It looks like a good product to me, just a bit on the pricey side for my tastes. I'd like to see something like this without the display, more in the $50 to $75 range. I think they would sell a lot more units.



Latole said:


> Power conditionner won't reduce voltage.
> Variac is the tool you need.


The item mentioned in post #42 (and post #1) is not a power conditioner. It reduces the line voltage to levels a vintage amp was designed for.


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## player99

Will this Variac work?









YaeCCC 5 Amp Variable Auto Transformer, AC Variable Automatic Voltage Regulator Converter(500W) : Amazon.ca: Tools & Home Improvement


YaeCCC 5 Amp Variable Auto Transformer, AC Variable Automatic Voltage Regulator Converter(500W) : Amazon.ca: Tools & Home Improvement



www.amazon.ca


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## pipestone62

I looked for a Variac for a long time and yes when you search you can find a lot of cheap/ low priced made in China Variacs like the one pictured above on Amazon, etc. I was not comfortable buying a made in China Variac that I’m sure is not CSA certified, and could possibly malfunction and damage my amp. I just can’t see how the cheap Variacs can be any good when the made in USA ones or CSA approved are $ 400.00 - $ 700.00, something doesn’t seem right.

I met a guy recently who has some nice vintage fender amps and he said the Brown Box made a huge difference in the tone and feel with his vintage amps. I just found the brown box really expensive and was happy to come across The Vintage Sound Workbench products. 
FYI: I have used a Furman power conditioner for a long time, it has a digital readout which I have checked with a good quality power meter and I generally have 120-122 volts power supply in my guitar room powering my amps.


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## pipestone62




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## bluehugh2

Knocking down the voltage does not regulate the voltage... so you need a Power Conditioner and a Variac...
Brown Box is one that I have to knock the voltage down for my vintage amps that were designed to see 110v.








AmpRX BrownBox Tube Amplifier Input Voltage Attenuator


5A Input AC Voltage Attenuator for Full-sized Tube Amplifiers, with LCD Voltmeter, 4 Selectable Input Voltages, 4 Selectable Output Voltages, Bypass, and Braced All-metal Chassis




www.sweetwater.com


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## traynor_garnet

player99 said:


> Will this Variac work?
> 
> 
> 
> 
> 
> 
> 
> 
> 
> YaeCCC 5 Amp Variable Auto Transformer, AC Variable Automatic Voltage Regulator Converter(500W) : Amazon.ca: Tools & Home Improvement
> 
> 
> YaeCCC 5 Amp Variable Auto Transformer, AC Variable Automatic Voltage Regulator Converter(500W) : Amazon.ca: Tools & Home Improvement
> 
> 
> 
> www.amazon.ca


Bought one of these in Canada so must be safe. I’ve been using it for years as my amps were built in 1965 and want 110 volts. I think my amps sound better at 110; less strident, softer transient (loud tube rectified Traynor Bass Masters). I’ve ‘browned them out’ just to see what it sounds like, but my favourite is around 105-110.

I had read that the meter readings on cheaper ones may be inaccurate so I scooped it out with my digital multi meter and marked different key voltages on the dial. The built in meter is pretty close.

Don’t expect miracles, but they work well with old amps.

TG


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## Paul Running

traynor_garnet said:


> but my favourite is around 105-110.


Yes, better to keep it on the low side of the spec.


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## player99

traynor_garnet said:


> Bought one of these in Canada so must be safe. I’ve been using it for years as my amps were built in 1965 and want 110 volts. I think my amps sound better at 110; less strident, softer transient (loud tube rectified Traynor Bass Masters). I’ve ‘browned them out’ just to see what it sounds like, but my favourite is around 105-110.
> 
> I had read that the meter readings on cheaper ones may be inaccurate so I scooped it out with my digital multi meter and marked different key voltages on the dial. The built in meter is pretty close.
> 
> Don’t expect miracles, but they work well with old amps.
> 
> TG


It says 110v on it. Does that make everything off spec?


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## Paul Running

The voltage ratio is linear, all the transformers secondary's voltages will follow the primary With a SMPS as in the Crate V series, there is better rejection to line regulation...mains variations will have virtually no effect to the DC output voltages which helps keep the stages tight. Check a SMPS wall-wart, the line regulation is typically spec'd at 100-120VAC.


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## Paul Running

player99 said:


> Will this Variac work?
> 
> 
> 
> 
> 
> 
> 
> 
> 
> YaeCCC 5 Amp Variable Auto Transformer, AC Variable Automatic Voltage Regulator Converter(500W) : Amazon.ca: Tools & Home Improvement
> 
> 
> YaeCCC 5 Amp Variable Auto Transformer, AC Variable Automatic Voltage Regulator Converter(500W) : Amazon.ca: Tools & Home Improvement
> 
> 
> 
> www.amazon.ca


This lad has a take on variac tolerance, some other interesting videos too.


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## Jimmy_D

You could read this by RG Keen - vintage voltage adapter, grab a Hammond 166N12B transformer and make one for way under $100, there's not much to it as you can see.

(I can't find it right now but I know Robinette amps has a layout somewhere over there that may be easier for some to follow, also based on the Keen schematic)

I'm going to order a transformer and enclosure right now and make one of these.

Edit - check this thread for Rob's layout and a "discount" build thread...


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## Jimmy_D

Well I did it and I'm surprised that it has quite an affect, in a good way. I just finished it and ran my '71 super reverb through it and the reverb on 105 volts is the best it's ever been, first impressions between 105v and 119v, there's slightly less boom and maybe it's even slightly compressed, bass somehow seems a little tighter - thanks for the idea gents I'll have to play with this some more but no doubt it's going straight into use in my music room.

Here it is and BTW it did come in under $100, by about 20 cents, mainly because I just couldn't build it in a plastic enclosure... I built it so it can stand up on the floor behind my amps but obviously you build it in any configuration, I think I should have added an inrush protection circuit to calm the beam-me-up-scotty sound I get hear when I flip on some amps, but maybe later.

I might post a quick build thread in the amp section but essentially the top outlet is wall voltage and the bottom is toggleable between -6% and -12% Those panel meters are pretty accurate to within a few tenths of my DMM.


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## IQC

_Why do you think 128 volts is too high for your amp ?
Where information come from ?_

From what I have researched on the internet and chats with amp techs over the years, Voltage has increased since the 60's. Some vintage amps were built for 110 volts (for example a 60's Fender Deluxe Reverb). People with old amps like this sometimes use products like AmpRx Brown Box to lower the voltage going into the amp. They say it improves tone and helps protect the precious vintage components. Seems to make sense to me. I have a few older amps made in the late 70's. I researched and found that the transformers in these amps were built to handle 120 volts. I still use a power regulator/surge protector but no need for a device to reduce voltage. I use a regulator as I regularly play in some very dodgy old venues and like to have consistent power going through these old amps. It's supposed to help give a consistent tone but these amps sound good with or without going through a regulator. Good to have surge protection though.


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