6L6 in a Champ?

11 Gauge · March 13th, 2004, 04:32 PM

just curious - is this do-able? in particular, can i keep the 5Y3 in there, and just up the cathode bias resistor to, say 600 ohms and the pairing cap to 50 microfarads?

anything else i might need to bolster up?

i'm not looking for extra volume or anything, just tend to favor 6L6s and have a bunch lying around, and no 6V6s (other than the one in the Champ now). 6V6s tend to sound a touch soft to me - 6L6s just right. so basically it's a 'texture' thing and has nothing to do with volume, for my needs.

i figured this amp is so simple that it would be a great candidate for reversible modification.

thanks for your thoughts!

JDO · March 13th, 2004, 07:36 PM

depends on the champ. if it's a tweedie, no. if it's a bf, that's fine. the pt in a br/sf champ is the same pt used in the princetons. most people don't really worry about trying to rebias them, although it might not be a bad idea. all the guys on the fender forum swear by rebiasing a champ witha 1k or a 1k5 resistor and putting a 50/50 bypass cap in - and that's with a 6v6. i would guess the same is true with a 6l6. but as far as safety, as long as it's a bf/sf champ and the tube isn't red plating, you're ok.

Dacious · March 14th, 2004, 12:42 AM

A cathode biased single ended amp with limited power like the Champ can have a 6L6 or 5881 dropped in with impunity. Just give the power transformer a quick feel after it's run for a while, to make sure you can still touch it - it's not getting too hot. As noted the Princeton runs two 6V6s and extra 12AX7s off it, so it should have no problems with the 6L6.

It will sound different, but maybe not better. You will likely get more power and mids but no more bass response.

The pinout of the tubes is the same. Rebiasing will probably not get much more power nor much of a different tone, because cathode biasing drops power compared to fixed, and the limiting factor is the power available from the transformer - reduce the cathode bias resistor to increase current draw, and you'll likely find plate voltage will drop to compensate.

A Tweed Champ may run into problems with current draw on the heater circuit, as a 6L6 draws much more.

alvis · March 16th, 2004, 09:35 PM

I got this one ,Silverface, in a pawnshop 2 years ago for 52 bucks.It had a torn 10" alnico speaker and badly enlarged baffle.Soooo,I removed the tone stack & the feedback .Changed bypass caps & put axial filter caps under the chassis.Put in a passive tone control like a guitar just to cut some highs.And stuck that RCA 6L6 right up in there.I corrected the baffle hole and threw that repaired Carvin 10" speaker in there until I score another alnico.I stuck a slightly larger 8ohm output tranny in there .I take it on the road ,using it for radio appearances and very small club gigs where I'll jack the champ output into the speakers of my Marshall combo

Yes ,I can hear it over the drummer

March 13th, 2004, 04:32 PM	#1 (permalink)
11 Gauge Friend of Leo's Join Date: Mar 2003 Location: The East Coast Posts: 3,085 10 Photos	6L6 in a Champ? just curious - is this do-able? in particular, can i keep the 5Y3 in there, and just up the cathode bias resistor to, say 600 ohms and the pairing cap to 50 microfarads? anything else i might need to bolster up? i'm not looking for extra volume or anything, just tend to favor 6L6s and have a bunch lying around, and no 6V6s (other than the one in the Champ now). 6V6s tend to sound a touch soft to me - 6L6s just right. so basically it's a 'texture' thing and has nothing to do with volume, for my needs. i figured this amp is so simple that it would be a great candidate for reversible modification. thanks for your thoughts! __________________

March 13th, 2004, 07:36 PM	#2 (permalink)
JDO Tele-Holic Join Date: Mar 2003 Location: Pittsboro, NC Posts: 603	depends on the champ. if it's a tweedie, no. if it's a bf, that's fine. the pt in a br/sf champ is the same pt used in the princetons. most people don't really worry about trying to rebias them, although it might not be a bad idea. all the guys on the fender forum swear by rebiasing a champ witha 1k or a 1k5 resistor and putting a 50/50 bypass cap in - and that's with a 6v6. i would guess the same is true with a 6l6. but as far as safety, as long as it's a bf/sf champ and the tube isn't red plating, you're ok. __________________ clean as a whistle

March 14th, 2004, 12:42 AM	#3 (permalink)
Dacious Friend of Leo's Join Date: Mar 2003 Location: Godzone Posts: 2,623 35 Photos	A cathode biased single ended amp with limited power like the Champ can have a 6L6 or 5881 dropped in with impunity. Just give the power transformer a quick feel after it's run for a while, to make sure you can still touch it - it's not getting too hot. As noted the Princeton runs two 6V6s and extra 12AX7s off it, so it should have no problems with the 6L6. It will sound different, but maybe not better. You will likely get more power and mids but no more bass response. The pinout of the tubes is the same. Rebiasing will probably not get much more power nor much of a different tone, because cathode biasing drops power compared to fixed, and the limiting factor is the power available from the transformer - reduce the cathode bias resistor to increase current draw, and you'll likely find plate voltage will drop to compensate. A Tweed Champ may run into problems with current draw on the heater circuit, as a 6L6 draws much more. __________________ My other Telecaster is a Thinline The Tele Bible, Ch 1, v 10 Love thy Telecaster, covet not thy neighbour's Strat!

March 16th, 2004, 09:35 PM	#4 (permalink)
alvis Tele-Meister Join Date: Mar 2003 Location: TN Posts: 326	Quasi Super Champ I got this one ,Silverface, in a pawnshop 2 years ago for 52 bucks.It had a torn 10" alnico speaker and badly enlarged baffle.Soooo,I removed the tone stack & the feedback .Changed bypass caps & put axial filter caps under the chassis.Put in a passive tone control like a guitar just to cut some highs.And stuck that RCA 6L6 right up in there.I corrected the baffle hole and threw that repaired Carvin 10" speaker in there until I score another alnico.I stuck a slightly larger 8ohm output tranny in there .I take it on the road ,using it for radio appearances and very small club gigs where I'll jack the champ output into the speakers of my Marshall combo Yes ,I can hear it over the drummer __________________ http://www.myspace.com/alvinyoungbloodhart