Voltage and Tone

Keith Hilton · From: 248 Laurel Road Ozark, Missouri 65721

I think everyone knows that so called 120 volt AC house current can vary greatly. At my house I have measured readings from 108 to 134 volts AC. Today it read 127.8 volts. When you go to a strange location ,no telling what the voltage will be when a big air conditioner kicks on and off. This might be one of many reasons why we have better tone one day, and a less quality the next day. Equipment will usually operate over a wide range of voltage. A particular piece of equipment will operate it's very best at a exact voltage. I was experimenting today, and I noticed that very ,very slight alterations of voltage made big changes in music tone quality. In my experiment I had run 15 volt DC power from one point,in several directions. As I ran power in different directions, it created a "voltage divider" at the point power was distributed.
I had started with 15 volts, but at the point power was distributed, the power wires had created a voltage divider droping voltage to around 11 volts. Since my chips would run anywhere in a range between 5 and 24 volts, the 11 volts did not bother me. Then I increased the voltage on up to 15. I could hear the tone start getting better with as little as a 1/2 volt increase.
This made me wonder about the roll changes in 120 volt AC house current causes in tone. I realize that most 120 volt AC current is run through transformers and voltage regulators in equipment before it gets to chips. Still, I feel that higher or lower---120 volt AC power can alter, in very slight ways, the output of transformers and voltage regulators. It is my opinion that it doesn't take much to change tone, and that these slight alterations in voltage can alter tone greatly.
Then I got to thinking about something. How many places have you played where most of the band "had" to plug into one power strip? Power is going to all kinds of different things at the power strip. The point of the power strip then becomes a voltage divider, slightly lowering voltage. I feel that it lowers voltage enough to cause tone changes in many cases.
I know AC works different than DC. Actually I think they call it changing the "Q" of a circuit. I can hear tone changes even down to 1/2 a volt change in DC voltage in certain cases.

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[This message was edited by Keith Hilton on 02 July 2000 at 10:16 PM.]

[This message was edited by Keith Hilton on 02 July 2000 at 10:19 PM.]

jerry wallace · From: Artesia , NM (deceased)

Hello Keith,Are you saying it could be benifical to use a AC transformer or a SS device to stalibize the AC fed to our amps?You are right in most cases I have been in, that way to many Plugs are ran off of the same AC circuits even tho they may be on several wall plugs ,many times they are on the same AC breaker/circuit.There are several devices that can regulate the AC at least to some degree.In fact some are available for computer use.I am in the photography business and A small variation in the AC voltage fed to a photo enlarger Light bulb,can make large changes in the amount and color temperature of a light source so I can see where it could have simular effects on electronics/chips.

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Jerry Wallace-Zum: D-10,8+8,Zum

-10,8+5 ,Nashville 1000,Webb 6-14E,Tubefex,ProfexII, ARTESIA, NEW MEXICO

[This message was edited by jerry wallace on 02 July 2000 at 10:51 PM.]

Ricky Davis · From: Bertram, Texas USA

I use to hear those changes in tone from place to place, in all my solid state amps I've had in the past. I've never heard a tone change in 200 different places I've played this past year, through my Fender Twin. That's just my observation and Keith where do you get all this great knowledge pal? You are one amazin' person. Oh and one more thing; your Hilton pedal is sooooooo consistant from one place to the next too; and I'm loving it more every day.
Ricky

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Ricky Davis
http://hometown.aol.com/sshawaiian/RickyHomepage.html
http://users.interlinks.net/rebel/steel/steel.html
sshawaiian@aol.com

Jack Stoner · From: Kansas City, MO

Keith, you are correct to say that AC power voltage will affect tone (and power). Obviously the lower the AC line voltage the more affect it will have. Some equipment is more affected by that than others, tho. I find my Nashville 400 is sensitive to AC line voltage but my MosValve 500 power amp (and Transtube Fex) do not seem to be as sensitive. There is one place that I work that it is really apparent and it will depend on how many amps are plugged into the stage power. But it affects tube amps too, as the lead player, who uses a Fender amp, was complaining the last time we played that he couldn't get his usual sound.

One of the things that can affect sound is how well the power supply is regulated. If the power supply is designed, with potential low AC power voltage in mind, and the power transformer and the power supply has regulated DC voltages the AC power line voltage (and fluctuations) will not be much of a factor.

It comes down to the circuit design, in most cases - that and the target price of the device. You could make a unit "bullet proof" but by doing so you could price yourself out of the market or limit the market.

Blake Hawkins · From: Florida

As Jack and Keith have said, power supply design is the major factor in regulating the
voltage that the amps and effects boxes see.
All of the internal circuits run on D.C.
in solid state equipment. In tube equipment the tube heaters generally run on A.C. and since they are like lamps, a small change in voltage can make a big change in performance.
Until recently, all amp power supplies were linear and very little regulation was used.
The better linear power supplies will have regulators so that a 10% change in A.C. voltage will cause little or no change in the D.C. given to the circuits.
Switching power supplies are now appearing and the characteristics are quite different.
A switching regulator will mantin a constant output over a range of perhaps 20% and when
it's limits are reached, it will stop working at all.
Back when I was testing such things, we found that Sony's professional tape recorder supplies, would maintain their rated output
voltage down to 90 volts A.C., after which
they shut down.
Maybe Mike Brown can comment on the test limits of the switching supplies in the new Peavey amps.
Blake

Bill Crook · From: Goodlettsville, TN , Spending my kid's inheritance

While not wishing to speak for Mr.Mike Brown, I find that in looking at the prints for my outfit's Mixer board (Peavey, of course),I find that it employs voltage stabalizing circuits throughout the system. This (according to the service manual) is to keep down gain differential swings in the systen as voltage swings occur in the primary 120 volt A.C power source. As Air Condition equipment and heavey current sources go on and off, this can cause squeals and EQ problems as the gain swings due to B+ rail changes. The "Peavey" equipment has the best and fast acting regulator systems I have ever tested.

Yes, A.C. power voltages can and do play a major part in the "TONE" and "SOUND" you are use to hearing.

(I,in no way, am connected to the "PEAVEY" company or Mr. Mike Brown) I (as a electronics tech and the one who has to do the repair of our stuff, ) just have a interest in the equipment that my band purchases and uses.

Jack Stoner · From: Kansas City, MO

Bill, what you have to look at is the Input Voltage specs for that unit. What we we're concerned with primarily is "low AC voltage" where it goes below the lower spec limits. Many times AC voltage on a stage is low and can even get in the 100VAC or lower range. That is where many amps or AC power devices will start having gain and tone problems.

I looked at a couple of Peavey manuals that I have and they do not give an AC voltage range. Just state 120VAC.

Keith Hilton · From: 248 Laurel Road Ozark, Missouri 65721

I make a device called a Digital Sustain, which can be powered by either battries or 120 volt AC adapter. When the battries get low, I have noticed a definite tone difference as complaired to running the device with the 120 volt adapter.

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Bill Crook · From: Goodlettsville, TN , Spending my kid's inheritance

Jack..

I understand what you are saying, but for the life of me, don't understand how the incomeing A.C. power system can drop below 108 Volt A.C.

At 100 Volt, my whole house would shut down. My 32in T.V. (I put it on a A.C. veriact) picture went to about 19 in and lost syn. sound went to h$%^ too.

I live in the T.V.A. area, so power here isn't a real problem. I guess you can say I'm very lucky.

Jack Stoner · From: Kansas City, MO

AC Power voltage regulation can be eluding. Having dealt with all the SSA Offices in the midwest, supporting their Networking Telecommunications and Hardware, I can tell you we had sporadic severe AC voltage problems in many offices (brownouts were a major problem).

As far as what voltage the equipment will shut down at varies. I had a large (300KVA @480VAC)UPS system for my Network computer room. It was set to go off line if the backup battery voltage that powered the UPS system during AC power outages dropped below 95VDC and the UPS would switch on line if the incoming AC voltage dropped enough to produce the same 95VDC threshold voltage out of the AC/DC converter portion of the UPS.

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