110v Power Strip?

[Mars Hall]

Having a few vintage amps, makes me ponder the 110v v/s 120v wall outlet difference. What are the differences in tone? Is it such a small difference to be insignificant?

Does anyone know of a power strip designed to deliver a consistant 110v supply? Something I can plug into a 120v wall outlet and step it down to 110v. I could use a variac but that would be cumbersome for a gig situation.

[mhuss]

I don't know anyone who makes one of these (they make 120v voltage regulators, but I have not seen any that were adjustable down to 115 or 110.)

You can roll your own, though:
http://www.geofex.com/Article_Folders/v ... ntvolt.htm

A Variac(r) is another, adjustable option.

--mark

[Mars Hall]

Thanks mhuss, I'll build one and let you know how it works out.

[Mars Hall]

I put it all together today. It works like a charm.

[Structo]

Did you build it like shown on that link?

[Mars Hall]

Yeah, just like the schematic. I went with the switch to change from Full, to -6 and -12.

The wall is 122 volts (first setting), the 2nd setting yielded 115 volt and lastly 108 volts.

I used it for about an hour last night. The unit never generated much heat, I thought it might run hot.

Worked real nice. It smoothed out the tone, less harsh on -6. The -12 was a little "lifeless" and "cold".

I plan on opening the amp and checking actual B+ changes. Will report when done.

Here's a picture of the amp I'm using.

[img768]http://i423.photobucket.com/albums/pp31 ... 0_0929.jpg[/img]

[Structo]

Cool, I'll be interested in what you find inside that amp compared to voltages on the schematic.

[grangeramp]

Me too! Good info here.

[Mars Hall]

For those interested. I checked voltages on my 61 Concert, for three different settings of my voltage corrector.

120 volt wall current
Filament = 6.3v
output tube pins 3 and 8 = 503
Center Tap = 517

113 volt wall current
Filament = 5.8v
3 and 8 = 475
ct = 487

106 volt
Fil = 5.5
3-8 = 446
ct = 460

It seems my filament voltage is right on at 120v. Should I run the amp on the lower voltage? 5.8v or 5.5v for the heaters seems too low. While the plate voltage seems closest on the 106v setting.

[Structo]

Hmm strange that it would have the proper heater voltage at 120.

How does the amp sound at the lower voltages?

[fishy]

I'm in for one of these.
I was going to buy a variac to try and bring my incoming down which is usually ~123v. With a hammond that puts close to 7v on the filaments. My goal is to get to the fialment voltage closer to spec.

I figure I just need to bring a Heyboer down a few volts and the Hammonds a few more.

Pete

[Structo]

Just looked at some Concert schematics.

What model circuit is the Concert I?

The AA763 has the plates on the 6L6's at 440v.

The AB763 also has them at 440v.

the 6G12 model has 456v.

http://www.schematicheaven.com/fender.htm

[Mars Hall]

Mine's the 6G12-A. After taking a closer look. The schematic states + or - 20% on voltages. At 450 volts, it gives me 90 volts either direction. 520 is not outside those parameters.

[chief mushroom cloud]

given this information, my gut feeling is that your PT is not original, and not correct for that amp OR...it is not correctly biased.

I've had three brown concerts in here over last 6mo....and all ran properly at 117VAC (from variac), and plates ran 450-460VDC w/ heaters at 6.3VAC

[Mars Hall]

given this information, my gut feeling is that your PT is not original, and not correct for that amp OR...it is not correctly biased.

I've had three brown concerts in here over last 6mo....and all ran properly at 117VAC (from variac), and plates ran 450-460VDC w/ heaters at 6.3VAC

I sure the PT is stock. I've seen other examples to compare. There is no evidence that anything was disturbed internally before I got the amp. It even had all the original filter, bias and bypass caps, which I replaced. When I get a chance I'll post some pics.

At 120volts the filament voltage did swing from 6.3 to 6.4. That much of a difference I considered insignificant for the post above. Compared to your 117 volts this seems about right.

Although 520 plate voltage does seem high, it is within the 20% tolerence stated on the schematic. If it was outside that then I would be more concerned.

Could any of the new caps cause the high plate voltage? I used as close to original values as possible. The only values that differ from original are the voltage rating on the filter caps. All new caps are TAD which are manufactured by F&T.

7 filter caps under the pan-
Old 20uf@525v
New 20uf@550v
Bypass caps
2 - 25x25uf@25v
1 - 25uf@25v
Bias caps
2 - 8uf@150v