How much wattage does an Express push with 6V6's?

[Bear]

Had my eye on this transformer http://store.triodestore.com/tf65wscta48o.html which might be a cheap route if it's enough. I've heard decent things about them elsewhere.

Bear

[Moose]

Blackface deluxe cooks the snot out of its tubes, so this tranny would be over the needed wattage requirements.

Heck, I run my 6V6 version at 350V and it only puts out slightly more wattage than a tweed deluxe, though it sure sounds a little louder.

[doctord02]

The original Express was advertised as 36 watts with EL34's and 22 watts with 6v6's.

[Funkalicousgroove]

Do you mean RMS or at stage volume? When you measure RMS you put a 1k sine wave into the front of the amp and measure the true rms voltage before distortion(Using an oscilloscope to look at the sine wave) then take the ac voltage square it and divide it by the resistance of your speaker load, so an amp rated at 20 watts when pushed to distortion can put out quite a bit more than 20 watts.

[Funkalicousgroove]

pushed it twice, sorry!

[Moose]

I don't think we "Mean" anything. It was just advertised at 22 watts. Advertising has to be taken at face value -- an estimate used to sell the product and for general info.

I haven't actually measured mine and I don't know anyone who has. However, that deluxe reverb power amp is a push pull pair of 6v6 running (depending on the amp) between 405V and 420V on the plates, fixed bias. Sound familiar? We run between 350V and 405V, depending on the tranny tap we choose, so it'll be close enough for government work.

Are you actually interested in RMS values? If so, I'd be glad to measure mine next time I get the scope out. I still have to build my high-wattage resistive load box, but when I do I'll be jonesing for a reason to use it.

[Funkalicousgroove]

I'd be interested to know, I find that most amps I work on actually put out far less clean wattage than they're rated at, like most 50 watt marshalls put out around 36 watts and most 100 watt put out around 68 watts(before distortion of course). I just thought I'd put that out there in case anyone who didn't know how to measure actual RMS output wanted to.

[loverocker]

> most 50 watt marshalls put out around 36 watts and
> most 100 watt put out around 68 watts(before distortion of course)

Really? The official test figures are 115W RMS at the onset of clipping for the 100Wer, with 170W at 10% THD (into 4 ohms).

[Funkalicousgroove]

I say test one yourself and see what you find, I can only go with what my scope multimeter and calculator say. Also, I would imagine that a 70's Marshall with 6550's and 515+ volts on the plates would put out more than 100W before clipping. I know if I were selling amps I wouldn't publish the stats on the "Runt of the litter"

[doctord02]

I know my '66 JTM 100 puts out 118 watts at the onset of clipping and an ear shattering 212 watts full up. It's quite the beast...

http://dnix.vigilante.net/amps.html

[Funkalicousgroove]

WOW!! GREAT AMP!!! Thanks for the pics!!

[dms]

Hmm.. What should the input voltage of the 1k sinewave be for making an RMS power output measurement - won't that influence the onset of clipping? What about an input voltage for general troubleshooting purposes (i.e. looking for parasitic oscillation, or just modeling the signal level from a generic guitar pickup)? Thanks, curious...

[ODwan]

I have once heard that an average guitar pu puts out about 0.1Vpp. That would be for a SC. Check DiMarzios site, they list voltage output for their PU's.

[glasman]

FWIW my Wrecker with JJ 6V6's puts out 18 watts clean into 8 ohms with a P/P load of 4K and a plate voltage of about 460 volts. 43 watts with EL34's.

Measurement technique.

8 ohm resistive load
1K sine wave

Measure Peak to peak output (before clipping)
Divide the P/P voltage by 2.8 to get into RMS
Square the RMS voltage and divide this by the load resistance.
The results is the RMS power.

Gary

[Funkalicousgroove]

Hey, thanks for the tip on the Fuchs Coax, Andy is sending me 30 FT, I'll get you a part # once I get it, He didn't remember it-