Super Champ 1983 - Optimizing

Bendyha

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I also have a spare EV10L/Force 10 which I'm afraid to sell in case I ever find another Super Champ I can use it in. . .
That was my thought, then I went and got a second SC that already has a EV in it...leaving me with two unused EVI (Force 10) and two EVM. Maybe I should clear-out some stuff as well.
 

Wally

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I also have a spare EV10L/Force 10 which I'm afraid to sell in case I ever find another Super Champ I can use it in. I just know I would regret selling it and would probably never find another one.


The EVL10 and the EVI/Force 10 are very different speakers. The speaker schmee shows use is an EVI in OEM trim...no label, no EV on the dust cover. The EV Force is the same speaker as the EVI but with aftermarket trappings...label and EV on the dust cover. The EVI/Force is a 150 watt speaker.
the EVL is a higher power handling speaker with a larger magnet.....here is one.
https://reverb.com/item/342487-electro-voice-ev10l-black
 

Wally

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Then the ones I have are both EVI's with the finned rear, no label but one of them does have EV on the cone, could have been done at a later date.

Scott, fyi, the Larger handling capacity EVs can have finned heat dissipators on them, too.....but again they are bigger than the EVI/Force. The finned radiators on any EV can be removed. You can see the screw holes in the magnet in the link I provided, and we can see the screws in the EVI/Force that schmee shows us.
 

hepular

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neg bias.jpg


yum. the smell of baking electrolytics!
 

Supa Necta

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Not sure if this is the right place, but stopped by a pawnshop yesterday on a lark and found an 82-83 super champ marked $269. Plugged in and it sounded great and they accepted my $250 offer! I think they must have thought is was the XD. My first piece of vintage(ish) gear!
 

Jowes_84

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Hi Bendyha

this is to let you know that I tried a similar approach as you did in post #35 - modified power amp - with my PRII.

- 150k grid leaks
- 15k grid stoppers
- .01 coupling caps

I like the result. Unsure whether there is an audible effect but for sure it did not make the sound worse. I assume it helped my PRII deal with all the signal and bass hitting the output stage during my modifications.

Thanks for the great thread again!
#35 is from quite a while ago and was very helpful for me, as well as most other posts in here.
 

Jowes_84

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Sorry for Zombie-posting around.
As I sold my Super Champ recently, and got a PRII instead, I am just going over a lot of details and your thread again.

On the compactron tube..., you did an excellent summary and the crazy dual-12ax7 adapter. Unmatched genius! I considered doing that but was too lazy. Actually, you could use that spare triode for a bias-wiggle trem ... ?

Now, I used to play my Super Champ with an RCA-branded 6u10. The middle triode is almost equal to an 12ax7, and used for the recovery stage after the 3.3M/47p attenuator. So no negative effects there.

The other two triodes in the 6u10 are equal to 12au7 triodes ... which actually works equally well, or maybe even better for the cathodyne phase inverter position.

The reverb recovery will be weaker - but I did not find that critical. I got a bunch of used 6u10s for 20 dollars + shipping to Germany. The RCA was the best one of the batch and sounds awesome. Prior to spending 100 bucks for a nice 6c10 I highly recommend trying a few 6u10s.

Longing for another Super Champ now :)
 
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Bendyha

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Sorry for Zombie-posting around.
......Prior to spending 100 bucks for a nice 6c10 I highly recommend trying a few 6u10s.
Longing for another Super Champ now

Hopefully not a Zombie, I'd rather think of it as a sleeping giant:twisted:

The prices asked for a 6C10 can be outrageous, but if one keeps the eyes open, occasionally a reasonably priced one is found on offer. They are usually so well made, that they will give you decades of reliable service, so just grabbing the one spare in case the installed one does "go" should not be to much of a financial outlay.

I utilized the spare triode in my twin 12ax7 adapter as a parallel V3B (mixer) stage. This is the stage that gets blasted by the lead drive to create the lead tone, and having the two sharing the task seems like a good idea - I have made the cathode resistor bypass cap switchable in/out (with a foot-switch and Vactrol) this boost/cut circuit is probably the best (or at least most readily useful addition) mod I did to the amp.
The four options of the two channels each with or without the boost are all distinct sounding, with clear steps between clean/fat clean/crunch/overdrive, and with the addition of the separate lead drive pot I added, the amp offers a wide rage of sonic settings.
I have not written this up with the fullness that I have many of the other things I did, (maybe I'll get around to it sometime...keep meaning to) most of the mod has been mentioned in bits.

Although I do like the idea of a tremolo, I think I would rather have one in a separate unit that I could use with different amps. maybe even have a stereo unit to place in the middle of my two SC's. All the parts are lying around to make one...maybe I will find the time sometime.
 

Wally

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As for ‘zombie thread’, imho any thread about amps which Bendyha starts should never be classified as such. The insights therein are timeless.
 

hepular

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Sorry for Zombie-posting around.
As I sold my Super Champ recently, and got a PRII instead, I am just going over a lot of details and your thread again.

On the compactron tube..., you did an excellent summary and the crazy dual-12ax7 adapter. Unmatched genius! I considered doing that but was too lazy. Actually, you could use that spare triode for a bias-wiggle trem ... ?

Now, I used to play my Super Champ with an RCA-branded 6u10. The middle triode is almost equal to an 12ax7, and used for the recovery stage after the 3.3M/47p attenuator. So no negative effects there.

The other two triodes in the 6u10 are equal to 12au7 triodes ... which actually works equally well, or maybe even better for the cathodyne phase inverter position.

The reverb recovery will be weaker - but I did not find that critical. I got a bunch of used 6u10s for 20 dollars + shipping to Germany. The RCA was the best one of the batch and sounds awesome. Prior to spending 100 bucks for a nice 6c10 I highly recommend trying a few 6u10s.

Longing for another Super Champ now :)


found a ge 6u10 for $3.50. sounds great in the super champ.
 

Wally

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Great price on that one, hepular. You may be aware of what that tube changes from the 6C10, which has three hi-mu triodes. The 6u10 has two medium mu triodes and one high mu triode. The hi-mu triode of the 6U10 sits on the reverb recovery. The other two triodes have lowered the gain in the third gain stage of the preamp and also in the cathodyne phase inverter.
 
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hepular

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Great price on that one, hepular. You may be aware of what that tube changes from the 6C10, which has three hi-mu triodes. The 6u0 has two medium mu triodes and one high mu triode. The hi-mu triode of the 6U10 sits on the reverb recovery. The other two triodes have lowered the gain in the third gain stage of the preamp and also in the cathodyne phase inverter.


yup. it does sound different. maybe a little crisper different on the highs. haven't kicked the lead channel in yet to see what happens. (& the 12au7's still in v2).

but: for folks who freak out about the price of 6c10s . . . there are options. I don't think I've tried a 6ac10--although there's one that i bought right after i got the amp that i need to double-check because it REALLY sounded different.
 

Wally

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Fwiw, there are differences other than amplification factors. To remain true to the design of the amp regarding the designed purpose of the tube, the 6C10 is the only option....it has three 12AX7 triodes, which were built with voltage amplification as a major design purposes. The 6U10’s high mu triode is much the same design. However, the lower mu triodes are built with other design purposes in mind....just as a 12AT7 was designed as a driver tube rather than as an amplification tube. The 6AC10 was designed as a color difference amplifier tube in color TVs.
and...yes....these various Compactron 12-pin tubes will function in place of each other; but just like using a 12AT7/12AU7 Driver in place of a 12AX7/5751/12AY7 type of tube, there has to be some difference other than gain. Whether or not one hears that difference or cares is another subject. Hey, there are differences in the sound of various 12AX7s....some hear them, some don’t. I have various different 12-pin triple triodes. I started gathering them years ago. I have a 6D10...triple triodes with an amplification factor of 57...between the 5751 and a 12AY7...closer to the 5751. It has other aspects that are different from either the AX type or the AT type. It will function in place of a 6C10, but it will operate differently...just as these other 12-pins do.
 

Bendyha

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There is another compactron that one could use, and that is the 7689...if you where lucky enough to find one. The 7689 12BA base pin-out is a bit different than the 6C10 12BQ base, but the tube itself is a triple triode 12AX7 with all the best features.
I should think that if you rewired the base, and put one in, you should never have to change it, even the standard 6C10 seems to last for a very long time.

upload_2020-6-21_23-29-13.png
upload_2020-6-21_23-30-5.png
upload_2020-6-21_23-31-11.png
 

Jowes_84

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Hi guys,
Big apology needed.
Just realized this today while toying with my new-all stock Super Champ. Sorry hepular, I hope the 3,50 were stretching your budget too much:)

Did some tube rolling and the stock 6C10 (I still have another spare) as well as two different 6u10s got tested. There is an audible difference in the clean as well as lead channel. Although, I like the result of the 6u10 sonically, it is not what the amp calls for.

My old SC, which I rewired to original circuit, put an EV force 10 in it, and tried with an RCA 6u10 sounded great with it anyways - I even preferred the sound to the stock and Sylvania 6C10s I tried.

With the more original SC amp I own now, the 6C10 sounds tighter, 6u10 smoother (which makes sense, lot less gain).

Great price on that one, hepular. You may be aware of what that tube changes from the 6C10, which has three hi-mu triodes. The 6u10 has two medium mu triodes and one high mu triode. The hi-mu triode of the 6U10 sits on the reverb recovery. The other two triodes have lowered the gain in the third gain stage of the preamp and also in the cathodyne phase inverter.
I assumed because it was named v3b in the schematic the stronger triode equal to a 12AX7 would be the middle triode in the main signal circuit ... but, Wally is right, its in the reverb recovery. So... I am mistaken.

The only way the 6u10 would make sense was to rewire the triodes, so that the strong, high-mu triode would be used for v3b, the lower mu-triodes left for cathodyne PI as well as reverb recovery. But I dont think this makes much sense. I am not going to attempt it.
 
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