fender tweed champ pt

[JoshBernstein]

Hi....
Im about to start a tweed champ build and i was wondering if a pt i currently have would be suitable. It has the standard 6.3v and 5 volt windings, but im a bit concerned about the ht windng, which is 330-0-330. Are those voltages to high? If so, how should i go about reducing them?
Thanks in advance!
-Josh

[jjman]

365-0-365 allegedly yields 420V on the plate. 320-0-320 allegedly 350V.

[JoshBernstein]

Then i should probably be okay.... ill be using a jj 6v6 which can take a lot of voltage in the plate. Thanks for the help!

[stretch2011]

With a 325-0-325 I got 400v on the plates using new tubes. Might want to increase the dropping resistor size and or get a nos rectumfrier

[Stevem]

Mr Kendrick, what ever happened to the other amp you where having issues with?

[rp]

I used the Mojo tweed Champ PT and got like 380V with a 620R rolling 6V6s, sounds great but I don't like raising the Rk so much with 470R I recall close to 400V. That mojo PT GETS HOT but seems fine. I also used a Hammond HX372X and remember the Pv making me happy w/ Kr @ 470. For me these things sound best below 370V and the cathode R close to what it's supposed to be. Meaning you can stick 1K in there to bring the Pv down but that doesn't mean you should. The 25/25 cap on V1a isn't optional.

[JoshBernstein]

Thanks again for the replies... ill have to see what kind of voltages i get when its done.
To mr. Stevem: I killed the 120hz hum by moving the preamp ground point away from the pt, and then just reflowed all of my solder joints. Theres som 60hz hum left, but its at a relatively acceptable level.

[billyz]

Best way to reduce hum in a champ is to add another filter cap and resistor to the filter bank. I used a 20uf x500 from the rectifier , then a 620 ohm 5w , then the stock filter bank. I used those values because that's what I had. No need to mess with the filament circuit. If the can is good and has 4 sections use the unused section.

[Mark]

Josh, if you don't have the chassis or cab, why not build a Princeton as you have more real estate to play with and you have a tone control as well.

The output transformer is a big deal with these amps. As the girls say, "size matters", the classic tone output strikes me as a good option.

http://www.classictone.net/40-18031.pdf

The power transformer has some good options too.

http://www.classictone.net/40-18027.pdf

[rp]

The output transformer is a big deal with these amps. As the girls say, "size matters", the classic tone output strikes me as a good option.

I've used this one, posted about it in the past, sounds like mud to me:

http://triodeelectronics.com/tfchxfwi48oh.html

Mine was bought like 15 years ago maybe they improved it. But now Triode has other Champ options like the 15W. I still swear by the Allen OT, it keeps the Fender sound unlike some other beefy Champ options (Edcor).

I've build 3 tweed Champs, none hummed even into 12"s, not tooting my horn, just noting it can be done. Played real ones, no big hum problems there either. Uping the capacitance is cool, BF/SFs sound great too, but a ~10W amp will never punch, the original low tweed capacitance makes them loose but also helps them sound fatter and fuller to me.

[Mark]

but a ~ 10 watt amp will never punch

What do you mean by that?

The Classic tone transformer I refer to has a 5K primary to allow other tube tubes such as a 6L6 to by used or two 6V6's. I've found the increase in wattage doesn't mean the amp was significantly louder, but there was more girth.

Should anyone choose to go with two 6V6's, the stock power transformer won't cut it.

[rp]

but a ~ 10 watt amp will never punch

What do you mean by that?

It won't move a lot of air.

[JoshBernstein]

Finished the amp yesterday, and im getting 290 on the plate using a 330-0-330 pt.

[JoshBernstein]

Somehow.

[rp]

Very wrong resistor somewhere, e.g. 10K for 1K? Cathode resistor on output right?