AC voltage affect on tone

[Tuna141]

I thought I'd share an interesting test I performed over the weekend:

I stumbled across a variac (variable transformer) that I had over the weekend. For kicks, I decided to see how varying the AC voltage to my Mark III and IIC affected their tone.

I varied the input voltage to each amp from 106VAC to 128VAC (roughly +/- 10% from nominal 117VAC). Here's what I found:

- The AC fan in each amp changed speeds, as would be suspected - you could hear its pitch change when I changed the voltage.

- clean channel = I could only detect a very subtle change in tone when I varied the voltage. The tone seemed to get slightly louder and brighter when the voltage was increased. The change was barely noticeable.

- distortion channel(s) = A significant tone change was evident when the voltage was changed. At lower voltages, the output was quieter. As the voltage was increased, the volume got louder and brighter with more distortion. This difference was most pronounced at each end of the voltage range. The tone transition seemed to change most somewhere around 115-120 volts. I thought the best tone seemed to be around 120VAC. The amp seemed lively around that voltage. Conversely, the tone seemed a little subdued below 115VAC.
- The III seemed more affected by the voltage changes than the IIC.

Conclusion: For me, this quick test has confirmed that the AC voltage that an amp sees does affect the tone of the amp, and that voltage affects some amps and amp settings more than others.

I'll also add that although there was a tone change, it was not enough to make me run out and buy a voltage regulator or use a variac when playing live. However, if I were recording, and seeking the absolute best tone possible, I would make sure that the voltage was at least 120VAC.

 

[nwoforlif]

Hey Tuna

I found out the same conclusions but by accident. In my area, the hydro company varies the voltage from about 115 to 127 volts AC. In the winter it is low (115V) and in the summer it creeps up to (127V). I found this out measuring the line voltage after my VCR burned a fuse. This was caused by them giving me a high voltage condition. My dual rec would get noisy at high gain when set to bold and using silicon rectifiers. This was when the line voltage was really high at 125V. For now I go to spongy setting which lowers the voltage to the tubes and it quiets the noise down to nothing on the amp.

I am in the middle of getting a furman power conditioner to even things out to 120V and keep it there where the dual rec sounds the best. I heard this is the only way to be 100% safe wherever you gig. The dual rec has the best sound on days where the line voltage is 120V. Eventually this jumping in voltage will take its toll on my amp if I don't act upon it.

NWOFORLIF

- distortion channel(s) = A significant tone change was evident when the voltage was changed. At lower voltages, the output was quieter. As the voltage was increased, the volume got louder and brighter with more distortion. This difference was most pronounced at each end of the voltage range. The tone transition seemed to change most somewhere around 115-120 volts. I thought the best tone seemed to be around 120VAC. The amp seemed lively around that voltage. Conversely, the tone seemed a little subdued below 115VAC.
- The III seemed more affected by the voltage changes than the IIC.

Conclusion: For me, this quick test has confirmed that the AC voltage that an amp sees does affect the tone of the amp, and that voltage affects some amps and amp settings more than others.

 

[Meson Boogie]

Has anyone done any similar tests comparing 120V vs 240V export models? I would have thought the different voltages and the 50/60Hz difference might lead to a difference in tone, but then again the transformer might negate any such thing.

 

[Tuna141]

From the test I conducted, I think the AC voltage fluctuation may also be partially responsible for that "great tone one day, but not so great the next, although we never changed our settings" phenomenon that we've all experienced at one time or another.

 

[Xqzdust]

Certainly voltage variations affect tone but, I played drums for many years and some nights my cymbals just sounded awful. The only thing I could pin that to was my ears. Maybe the sound pressure levels you are exposed during the course of a day affect your hearing on a short term basis, I don't know, but the same cymbals with the same sticks on the same stage could be very bright one night and sound dull the next. I've had the experience with guitar as well so I know what you are talking about. Just wanted to introduce a different perspective

 

[MesaDCLP]

Voltage definitely has an effect on the tone. That's why they came out with the half power switch. However, at full power, the power at the outlet definitely becomes a variable and affects the tone as noted.

Not totally off topic, but does the Variac have an effect on the tone of half power modes, or is the voltage regulated at the amp and the tone is not affected until the voltage drops significantly?

If the outlet voltage has little effect, then you could find settings at half power that work at any location. However, I don't think the amps regulate … they just resist in lower power modes. This obviously is opinion, so any actual tests will prove the case.

In the lower power modes I view it as a gate or resistor. Only let x in, or only let x% in.

 

[stomper]

I can never predict what the power will be like in a club. I hate when my amp sounds different due to power or line noise. This can be found for just over $100 if you look around online. It works very well!

http://www.tripplite.com/products/product.cfm?productID=208

 

[Tuna141]

Not totally off topic, but does the Variac have an effect on the tone of half power modes, or is the voltage regulated at the amp and the tone is not affected until the voltage drops significantly?

If I remember correctly, the Variac affected the tone in both power settings - Class A & Simul-class.

 

[tiktok]

Hey Tuna

I am in the middle of getting a furman power conditioner to even things out to 120V and keep it there where the dual rec sounds the best. I heard this is the only way to be 100% safe wherever you gig. The dual rec has the best sound on days where the line voltage is 120V. Eventually this jumping in voltage will take its toll on my amp if I don't act upon it.

I bought a Furman after a gig where I blew two fuses on AC that measured 127, according to my deluxe Furman power distributor. Four hundred bucks later, I put the Furman power conditioner in the rack, plug the power distributor into that. I still see voltage variations, i.e. it's not 100% 120V. I stopped carrying it after a while because it was so heavy, and I've never had fuse problems since then.

 

[MrMarkIII]

Hey Tuna

I am in the middle of getting a furman power conditioner to even things out to 120V and keep it there where the dual rec sounds the best. I heard this is the only way to be 100% safe wherever you gig. The dual rec has the best sound on days where the line voltage is 120V. Eventually this jumping in voltage will take its toll on my amp if I don't act upon it.

I bought a Furman after a gig where I blew two fuses on AC that measured 127, according to my deluxe Furman power distributor. Four hundred bucks later, I put the Furman power conditioner in the rack, plug the power distributor into that. I still see voltage variations, i.e. it's not 100% 120V. I stopped carrying it after a while because it was so heavy, and I've never had fuse problems since then.

Power "conditioners" do nothing to the voltage. You need a voltage REGULATOR like the Tripplite mentioned above.
Furman makes the rack-mount AR-1215 which works great and also "condtions" (removes those nasty snarls and tangles, and leaves your electricity silky smoov! LOL).