6C10 to twin 12AX7's conversion

[TimC]

I own a Super Champ and the triple triode 6C10 is getting very expensive and hard to find. I was able to find a 12 pin plug and two 9 pin tube sockets at Antique Electronic Supply. I'm having a hard time figuring out what to use as a small box to mount the plug and sockets. I would like to have the two 12AX7's facing down or inward. It has to be kept fairly light weight or else I'll have to devise some kind of retainer that doesn't involve drilling the chassis. Does anyone have a suggestion as to what to use for the box? I realize the heater current will be a bit more, but I don't think it will be enough to harm anything. I asked this at another forum and had someone post a good idea to use the 6C10 socket screws (with longer screws) to hang the box.
Has anyone tried a conversion like this?

[Bob M.]

Sometimes, I will mount a triode (or dual triode) on a terminal strip and find a place inside the chassis for it. I know this is not ideal but it works. You could remove the 6C10 socket and put a 9 pin socket in its place then mount a single or dual triode somewhere else inside the chassis and wire it up. If you have a cool running amp, this shouldn't raise the internal temp too much. I've done this a few times in smaller amps that don't generate too much heat and it works just fine. I'm not sure I'd try this in a Class A amp though. Use common sense here. It's an inelegant solution but in a pinch...

Bob M.

[TimC]

Thanks for the tip Bob. The Super Champ is AB with two 6V6's. It's a Paul Rivera design and it is pretty crowded inside. It's not much bigger than the old class A Champ. I think he went with the triple triode to save room. I'll pull the chassis and see if this is possible.

[Gtr_tech]

Since the 6C10 has 3 triode sections, using 2 12AX7s would waste a triode. I would use a 12AX and a 6AV6. The 6AV6 is a single triode....essentially half a 12AX7 with a couple diodes thrown in...ignore those. They're cheap and plentiful.

[Gtr_tech]

Here's the datasheet....
http://tubedata.itchurch.org/sheets/093/6/6AV6.pdf

[TimC]

Since the 6C10 has 3 triode sections, using 2 12AX7s would waste a triode. I would use a 12AX and a 6AV6. The 6AV6 is a single triode....essentially half a 12AX7 with a couple diodes thrown in...ignore those. They're cheap and plentiful.

That's a good suggestion Gtr_tech. I thought I had some 6AV6's in a large box of tubes my brother gave me, but no luck. I just checked at Antique Electronic Supply and the socket and tubes are available, and cheap like you said.

[Pedro Vecino]

6C10 costs US$35 in Tubedepot. Replaced by two tubes with its mechanization, wiring, etc. is more expensive...

[TimC]

Pedro, I was thinking ahead to when the last of the 6C10's are gone. I don't think any will ever be made again. I expect my kid and grandkid will be using this amp for many years to come.

[Pedro Vecino]

DŽont worry about it. 6c10 are all american with very good quality and I've seen it work without problems for 25 years or more in Supertwins, Studio Bass and others. Buy three or four and you are covered for generations :-)
In the 80s it was said that some tubes of the old Ampeg SVT (6146 and 12DW7) were impossible to find and today are many in the market. Internet has changed this.
Regards

[IL Leone]

My first post, so if i "noob out" be gentle with me

I too worried about the availability of 6C10's too, but kept finding them here and there, many NOS, and am pretty ok now on not running outta them.

I just started using my super champ after yr's of it sitting idle. I blew the spkr and after careful research picked a ragin cajun 10" for it and it's a whole new amp! big bottom (for a tiny amp) and it became very sensitive to picking dynamics that I have been leaving it in the OD channel and just using the guitar vol knob to got clean to mean. I am now stoked to do some mods I wanted to do, add a footswitch for the mid boost, spkr jack and a few other reliability things from the SC fan site.

I currently have brimars in it and have NOS GE's (which it shipped with according to P. Rivera back in the day), I can try too. Anyone have a prefered 6V6 they like? Greg

[TimC]

New member here too Greg. I pretty much had the same experience with my Super Champ. I bought it used from a local kid back about 1990. I was never too impressed with the tone, so it sat unused. Last fall I re-capped it and installed a Celestion 10" Gold (alnico). What a difference that made. I don't know what brand speaker Fender put in it when it was made (Eminence?), but that was the tone killer. I guess Fender figured most buyers would be playing it using heavy overdrive where the subtle harmonics are lost; at least I can't hear them.
The original 6C10 is still good, and tests stronger than the NOS G.E. that I recently ordered on line. Yes, a speaker jack would be a good idea, along with an adjustable bias. I'd like to do this without drilling any holes or otherwise modifying the chassis.
This is a great little amp and I wished I lived where I could crank it up and let it wail. I had an unknown and drunk neighbor call and tell me he was coming with his shotgun if I didn't turn down the volume on a 100 watter one time. I pretty much follow his advice now.
Edited to answer 6V6 question: I started hoarding tubes back in the `80's. I have a fairly large pile of 6V6's to choose from. I have tested them all on a home made Champ using a Compu-bias and marked each with wattage. I have always biased amps to the max allowable wattage, but recently tried a couple ancient RCA's in the Super Champ at 8.8 watts each. It sounds great, and maybe these old tubes will last a bit longer running cooler.

[Pedro Vecino]

DŽont worry about it. 6c10 are all american with very good quality

I correct the above: there is a newly manufactured 6C10, which big distribution companies are using today. This is a compactron manufactured by Ei factory in Serbia. It is strange because nothing has been publicized.



I've compared with a 6C10 G.E. in a Supertwin Reverb and the quality difference is very noticeable. Does not have the dimension and round tone of the American. Sounds in the style of Ei ECC83 nickel plates (more thin and bright).
Regards

[Pedro Vecino]

More news about this strange tube:
This afternoon I measured several 6C10 (GE, Sylvania, RCA...) I have as a replacement for Supertwins and as expected, triode measures correspond to 12AX7 triodes. My Hickok 800 tester does not have compactron socket but I built an adapter for it on a noval base. 1100/1200 micromhos aprox. Same as a standard 12AX7.
But the surprise happened when I measured the "new" compactron: More than 3000 micromhos.., (almost twisting the needle) which indicates that is not a 6C10.
I found it strange that a European company currently manufactures a compactron with typically American construction (!) and the answer is here: Is another compatron model (most likely 6AC10) labeled as 6C10.
6AC10 (built originally for colour TV) costs approximately in USA $6. The same (I guess is a 6AC10: same base as 6C10 with big glass) costs in Europe 45€ (US$62).
Here is a picture of an original 6C10:

Good deal relabel tubes!