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Super Champ 1983 - Optimizing

Discussion in 'Amp Tech Center' started by Bendyha, Mar 29, 2014.

  1. Bendyha

    Bendyha Friend of Leo's Silver Supporter

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    Finally got around to getting myself a Super Champ – 1983 Rivera era. I've wanted one for a long time
    Why do I love this little amp? It's the originality of this basic but multi-talented little amp that facinates me. It has features that are not to be seen anywhere else, certainly not in this combination. I believe it holds a special place for Paul Rivera. Mine is in original condition, with only some of the tubes replaced, will I leave it that way, and respect its humble crudity and forgive its inherent faults, love it for what it is, preserve its integratie, whilst still plauding its virtues?
    No !
    Here is a rough cut gem, waiting for polishing. The research and development designers at the Fender factory, having to keep the penny pinching accountants "upstairs" happy. Also, this amp had to take it's place in the family row. It has more features than the Champ II & Bassman 20, is sort of on par with the Princeton Reverb II, but less than the Deluxe Reverb II, Concert II and Twin Reverb II. In many ways the family would have seemed complete without its existance, but none the less, Rivera placed this little amp in the range.
    Here we have lots of latent potential that awaits realization. Such a simple circuit, point to point wireing, more than adequate power transformer, and the basic layout, parts and design concept don't need toching.
    But I'm dambed if i'm going to settle for – " Lousy, thin sounding speaker","Forget the footswitch, it doesn't work", "Lead is ice-picky and buzzy", "Obsolete 6C10 tube" and all the other complaning comments one hears about this amp.Identify a problem, find its cause, think of a solution, correct the situation, move on up to the next stage.
    First step, replace the speaker. All sorts of speakers are recommended for this amp. The original upgrade of this amp, the Super Champ Deluxe, with its oak cab, came with a EV10 of some sort, in many photos it is clear from the vaned plate on the back that it is a "Force 10", some seem to have the flat magnet that would be a "EV10M" Paul Rivera recommends ]https://www.youtube.com/watch?feature=player_detailpage&v=HC25NwrRNvo[/URL] the illusive "EV10L", which many seem to doubt the existance of. He uses in them in his special limited edition "Venus 3", which is sort of the next generation of Super Champ. I sure wish I had a schematic of a "Venus 3", I have the 5, but that's a different thing.
    Anyway, I found myself a speaker like the one Paul Rivera recomends and the fact is, IT DOES NOT FIT !
    I've read of people bending and moving the reverb tank, but you can't take it off the top, and sawing 1/2" of the bottom, and fining some new way of mounting it is crazy. Besides the amp itself no longer fits, even with the tube cover removed, there is no room, one would have to move the tube over to the side, and the reverb transformer would still be touching the speaker. Have a look at the photos.
    Another thing which is undesirable, look how much of the speaker is covered by the baffle frame and Fender logo. There is only one solution, I need to make a bigger cab.
    Okay, I'll get back to you when I've got that done, and then I'll set to work on the footswitch problem.
     

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  2. Blue Bill

    Blue Bill Poster Extraordinaire

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    Wow, nice find. I think it's worth it to find a way to stuff the EVM into a cabinet. If you don't, I would be interested in taking it off your hands, so I can cram it into my SCXD. (o:
     
  3. Blue Bill

    Blue Bill Poster Extraordinaire

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    Good luck!! (I posted a dumb reply; tried to edit/delete, never mind.)
     
  4. Johnny Cache

    Johnny Cache Former Member

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    I think I'll keep mine as stock as possible. These are a classic amp and I wouldn't want to detract from it's vintage appeal. Although, I am planning to replace the speaker with a Lil' Buddy in a few weeks to help warm up the amp a little. Although I'll save the original speaker for a retro fit later. I've had mine for several years using it for practice and some recording, not much else. Now I'm starting to use it for some light Jazz dinner gigs because it's easy to carry and they don't want me blowing away the customers, which this amp could do. And I'd rather not haul one of my larger amps to these small venues.
     
  5. andyfromdenver

    andyfromdenver Friend of Leo's

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    Welcome, and let's see what you can do :)
     
  6. Bendyha

    Bendyha Friend of Leo's Silver Supporter

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    Cab is finished.

    The new cab is finished, and now everything fits inside without touching, and without having to modify the reverb tank or move tubes and transformers around. The new cab is four inches taller than the original. I probably could have got away with just adding one and a half inches as the bare minimum, but adding four makes the box square, which looks good, and is also easier to make. I also made it about one inch deeper. The wood is a South American hardwood, i'm not sure what sort. Before it became an amp cab, it spent about twenty years serving as bed boards, so it's well seasoned. Lots of planing, sawing, joining, routing, glueing, sanding and oiling, but now it's finished, i'm quite happy with the results.
    I played the amp in its original cab for a while this morning, then moved the amp chassis and reverb over, and was playing the new cab and speaker about five minutes later. A clearer, fuller, louder tone, and with volume, bass and master all turned up full, and the powerful neck humbucker of my Schecter Pete Townsend Tele driving it, this speaker showed no sign of being stressed in anyway, keeping the bottom tight, and the upper mids transparent. I'm impressed ! The only down side, is the weight, so I won't be taking it for walks. Besides, it's usually the bass player who loads and unloads it a gigs, while i'm coiling and uncoiling microphone cables.
    So, now I can spend some time working on and around the footswitch, then i'll be back to let you know what i've worked out.
     

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  7. Wally

    Wally Telefied Ad Free Member

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    BEautiful cab, Bendyha. One might want to question the lack of 'breathing' space for air for those tubes, though??? Two separate panels is hte normal approach.
    Footswitch....I would be imtersted if you can find a cure for the design flaw. I had a young EE guy...Masters....look at that problem, and he could see no way of dealing with the inherent problems....at least, he could find no easy and simple way.
    Weight? A problem??? Forgive me if you have a physical situation that challenges you in that way....but that amp can't weigh more than 35 pounds, can it?
    And....of course, Paul Rivera would l suggest the EVM for that amp! HE may have the last NOS EVM 10's on the planet??? I read somewhere yesterday that someone got one from someone..new one...maybe ??Rivera??...maybe not...something between $500 and $600!!!
    Hey, unobtanium can get expensive, right?
    BEndyha, you might try a 12AU7 in the reverb driver/lead gain position. IT sweetens up the reverb and the overdrive. There is enough gain in that Lead operation so that giving up a little bit is no problem. My two SC's still will scream high harmonics at the gods! I haveowned these little SC sicne before they were on the radar for the gems that they are....over 20 years. Magnificent little amps...I could sell one a week if I had an unending supply of them. I run Eminence ALK1028's in mine..the Alnico softens up the distortion on the high end a bit...as Alnico is wont to do. Very articulate, good full range speakers. IF I ever run across an EVM 10, I will do what I can to get it. I have two grey D120F JBL's, two Altec Lansing 417-8C's, some
    12" EV's, a 15" EVL....I am open to trades if anyone has the EVM 10's.
    Maybe I'll just build two bigger cabs and run the 417-8C's????

    FWIW, in that Rivera line, the Super Champ, the PRII and the DRII are virtually the same amps..but for the 6C10 in theSC. The two larger amps--the Concert and Twin reverb II--- do things differently; and those two amps don't move me like the 3 smaller amps do. Maybe it is becasue I like to run the output section at full bore???? The little amps do that without doing harm to the human ear. I run all 3 gain/voume knobs at '10'. Everything is richer that way.
     
  8. Bendyha

    Bendyha Friend of Leo's Silver Supporter

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    Thanks for the input Wally,
    As I mentioned, the cab is about one inch deeper than normal, so although it may look like the tubes are closed in, there is actually quite a gap at the top, more than usual, so I don't think there should be a problem.
    I was lucky enough to get my EV 10 from a HiFi buff who had been using it it a driver in a low powered bass horn. I paid around $150 for it.
    The idea with the 12AU7 is certainly a good one, and one that is on my long list of things to tryout.
    " I run all 3 gain/voume knobs at '10'. Everything is richer that way. "
    How true, maybe i'll get myself some knobs that go up to 12 and see what happens !
    "...no easy and simple way. "
    Well........... we'll see...........easy and simple sort of describes me quite well, but not shy of trying anything twice.
     
  9. Blue Bill

    Blue Bill Poster Extraordinaire

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    Beautiful job on the cabinet! It looks great. I'll bet it sounds awesome. I've been looking for an EVM-10 for a while, you're lucky to find one. Good luck with the footswitch, and your new "bouitique" amp!

    Huh, not sure what dtordal is up to...
     
  10. Mike H.

    Mike H. Tele-Afflicted Silver Supporter

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    I found one of the EV Force 10 speakers that came in the Super Champ Deluxe and replaced the stock speaker in my amp. It's tight, but does fit in the original cabinet. I noticed an immediate improvement in headroom, volume, and tone.
    Very nice job on your custom cab!
     
  11. Wally

    Wally Telefied Ad Free Member

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    MikeH, if that OEM speaker you took out was an Eminence, then almost any speaker would have improved the amp, ime...it has no bottom, harsh high end---just a really inexpensive OEM speaker...the worst Eminence I have ever heard. IF you had the Pyle...manufacaturer's code 1098...then that speaker has low end and some sparkle...but it is lacking in articulation.
    I have one of the Derek Trucks' Pyle's that I need to try in a SC. The 'Derek Trucks' Pyle has a bigger voice coil than does the OEM Pyle that FEnder put in the Super Champs.
     
  12. refin

    refin Friend of Leo's

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    I put a Force 10 in my Super Champ (when I had it).....amp came alive.
     
  13. Bendyha

    Bendyha Friend of Leo's Silver Supporter

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    The Footswitch

    So, I built myself a footswitch; A couple of DPDT stomp switches in an aluminium box, two LED's and resistors, a length of cable, and two stereo jacks. I've included the wireing diagram.
    Lets see what the problem is when using it, the way these footswitches seem to suck away volume and tone from the clean channel when they are pluged in. While i'm at it, can I get reverb with my lead channel, and maybe tame the lead gain down to make it a more usable channel, and if possible achieve all this without removing or changing any of the original parts..... Well, yes, most of these aims can be easly done. The only parts that need changing, are the ceramic caps that I wanted to upgrade to better sounding MKS anyway. Working out how to do this took me a while, and involved many a trial wiring of switches and poti's, to dial in diferent parts that I could flick in and out to compare sounds and levels with different settings on the amp.
    The following numbers refer to the marked parts on the schematics outcuts below, showing before & after my mods.

    #1 Volume and tone loss in clean channel from plugging in footswitch.
    The problem is that without the footswitch, the clean signal passes straight along the top of this schematic through the 3M3 resistor and the 47pF cap and on into the next stage, but here is also where the reverb return and lead get injeted back into the signal. The clean signal also passes down through the two 470k resistors, where on one side the reverb poti goes to ground, and on the other side, the 470k resistor lets the signal through to a Vactrol, which has many MegaOhms of resistance to ground in its constantly off position, and an open switch, hence infinate resistance. No problem here, as practically no signal gets lost through this combinded resistance which has a minimum of 470K when the reverb is turned right down. BUT... when the footswitch is plugged in, the vactrol comes to life,it's resistance drops to about 300 Ohms as it is there to ground out the lead signal. But this also means that the clean channel now sees the two 470K in parallel, halving the resistance to 235K to earth, and this is low enough that some bass frequencies are being filtered out, resulting in a volume and tone loss.
    Solution; Unsolder, and lift up the one end of the two 470K resitor where they both come together, add on a 680K to the resistor going to the Vactrol, and a 270K to the other, then solder the two ends into where the 470K's where raised out of. Now we have 450K when these are measured parallel, and the sound is the same as when the footswitch isn't plugged in.
    Ah,... but as you notice, now we have 740K to ground when the footswitch is removed, does this make the clean channel sound different ? No, the 450K is big enough to block out the bleeding off effectively, and so the 740K does not have more to block out.
    Does the reverb become more quiet ? No, the Princeton has a 1M2 resistor in this place, and its reverb sounds fine. (Princeton owners only need to add to their even lower 220K problem resistor they have on the Vactrol side, a 560K resistor to raise the parallel resistance from the even lower 186K they have, up to somewhere in the 470k range.)
    Does the Lead channel change? A bit, but to the better; making it ever so slightly softer sounding.
    As to whether any tone is also being bled off in the cable due to capacitance effects, interferance being picked up, or some sort of cross-over intermodulation as the signal is going to the footswitch, which is sometimes postulated as being part of the footswitch problem ? I could not notice this with the relatively high quality cable that I used, but as to whether other cables show any of these effects I can not say. I hear no adverse effects from my pedal now.
    So, nothing removed, quick and easy to do, and a just as simply reversable mod.

    #5 & #6 Getting reverb on the lead channel, and tameing the lead gain.
    These two problems go hand in hand. There is such a ridiculous amount of gain on the lead channel, that it not only drowns out the reverb, but everything else as well. A simple solution to this problem is to change the relationship between the 100K and the 1M resistors coming from the reverb transformer and 1000pF cap, and leading to the lead switch. These are acting like a set gain poti turned up to just over 9.
    After trying out various alternatives, I found the simplest and most effective solution was to raise up one end of the 1M resistor (right next to, and in the same direction as the two 470K resistors before), and add a resistor to its end, which goes into where the 1M came out. The wire coming from the back of the volume poti, that is joined to the end of the 1M that wasn't raised, now needs joining to the other end of the resistor at its junction to the new resistor, at the same time adding a 47pF MKS cap parallel to the1M resistor. ( See photo below)
    As to which value the newly added reistor should have, I found that 390K gives me a nice warm crunchy drive that reacts to the volume setting on my Tele with quite powerful pickups. With the Lead volume set at 6, the volume was much the same as switching from the clean channel, and the reverb comes through at just an ever so slightly lower volume. So I would say that a 330K resistor with a 470K trimpoti on top would let me dial in most gain amounts I would want to match any of my different Tele's.

    #7 This cap was a .0027µ on my amp, it looks to be original so I left it. On the original schematic it is marked as .001µ – Anyone else have this value?

    #2 & #3 & #8 Are all ceramic disc caps that are renowned for sounding brittle and are generaly deemed for not beind desirable to have in the sound chain, so I swaped them all out for MKS caps. I left the value of #8 as it was, as besides setting the balance of the clean tone, there is also some canceling out of the lead tone from the opposite phase of the clean signal coming through it, and set as it is, it seems optimal.
    Raising the values of #2 & #3 as I did, seems to make the tone of the reverb sound a bit less like a concrete storm drain, by adding a touch of the hardwood forest in winter quality. The lead wins on mid authority.

    #4 Was changed from .001µ to .01µ. ( I forgot to change this on my drawing ) This warms up the sound of everything a bit, but less than I first expected, and was actually one of the first things I changed, before all the other changes, as it seems to suit my EVM 10 speaker. The icepick sharpness of the treble control was unusable above a setting of 2 before. Now with no loss of clarity or transparency, settings of up to 7 are posible before becoming painful at high volumes.

    So thats it for today. If anyone decides to also try out any of these ideas, let me know how your amp reacted, and let me know if I made any mistakes or have not clarified my ideas properly.

    I've got several other ideas for this amp in the planning and trial stage, and will report back again when I have a few more results.

    Bendyha.
     

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  14. chris m.

    chris m. Poster Extraordinaire

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    I have the original OEM EV speaker in mine, and it sounds great. It is a tight fit, but it fits. It came with the amp when I bought it way back in the first year that Super Champs were available. '82 or '83?

    I still have the original footswitch, too. When I use it I notice that I can get a stronger sound out of the clean channel if I hit the channel switcher. (This is with the volume knob pushed in so that it doesn't actually switch channels when I hit the knob.) However, I generally don't bother with the footswitch since I no longer have much use for the dirt channel. I prefer to crank the clean channel. At home sometimes I might use the dirt channel, but in that situation I don't need the footswitch. In other words, I go for one or the other, not switching back and forth. But I hate how the reverb cuts out when you switch to the dirt channel, so I typically stay on the clean channel, which gets plenty dirty if you crank it up.
     
  15. andyfromdenver

    andyfromdenver Friend of Leo's

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    Bendyha, you're pretty darn awesome (I would say kick___, but keeping it clean) :)
    Good work!
    Also, good food for thought Wally.
    Really nice thread!
     
  16. Wally

    Wally Telefied Ad Free Member

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    food for thought...yes. I would have to do an A/B comparison to know what I would think of these changes. I admire the work and analysis that you have done, Bendyha.
    I do have two of these Super Champs...so if I were so inclined I could make these changes..ad build my double footswitch that I have had the parts for for many years. However, there is at least one thing about the changes that I don't care for. I love the gain of this amp....as well as the cleans...as well as the tweed-like tones that I can get out of it. I am running a 12AU7 in the reverb driver position, so the reverb is sweeter than stock and the gain has been decreased just a small bit in the Lead function.....still screams high harmonics like very few amps I have ever heard, so the decresae with the 12AU7 is noth significant at all. Any significant chagne woudl not be what I would want. I run these amps with all gain controls at 10....and all sounds are available from clean to high gain with balanced output. Magnificent amps, imho.
    IF I were to buy a 3rd Super Champ, I might well do these mods to it out of curiousity. Until then, I don't want to change what I have...because they work for what I need.....since I don't use them in any situation where I would need a footswitch.
    Bendyha, I appreciate your work, and I will keep your mods in mind for the time when I find another Super Champ to mess with....I would prefer it to be in less than excellent cosmetic condition, though.

    Kudos on the work, Bendyha.
     
  17. andyfromdenver

    andyfromdenver Friend of Leo's

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    I want one of these so bad.
    I'd jump at $500
     
  18. Wally

    Wally Telefied Ad Free Member

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    LOL, Andy....that would be a steal, imho.....handwired switching reverb amp with big time 'street cred'. Figure out what FEnder would be charging IF they were to build this amp today, and consider that NOONE else has ever built anything like it. My guess that it would be well north of $2500. IT ain't gonna happen.
    When I bought mine circa '93 for $175 apiece, I knew they were worth far more than that in practical terms. I paid that price for both even thought the second one came empty....the guy didin't want to leave the little 10" Altec Lansing in the amp!! Darn!! (;^)
    My estimation of these amps is the same as what I think of Pro Sonics...if they were worth $1500 in the market, that would be fair. Look at what FEnder offers for that money...and compare. Hint: nothing compares when soicns along with build quality is compared.
    My buddy got lucky last fall while visiting with a young performer who was using a Super Champ---with the footswitch plugged in. My friend told him if he ever wanted to sell it to let him know. The fellow called him the next Monday....$400!! He probably needed the money to buy a ???Blues/Hot rod amp, right? LOL. With the footswitch plugged in, he had never heard the amp do what it should. Outside of that kind of 'foolishness', the best deal I have heard of is approaching $800. Mine would never be sold for that little, either....I would request that they go on the funeral pyre with me if I could not get what they are truly worth.
     
  19. BopT

    BopT Tele-Afflicted

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    Great looking cab! Good tip on the 12au too!
     

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  20. chris m.

    chris m. Poster Extraordinaire

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    Looks like they're going for around $900 to $950 on EBay, which is pretty high. Just for comparison, I was able to get a super cherry, just worked on, '72 Super Reverb, blackfaced, with 4 CTS Alnicos, for the same $$. JCM800 combos can also be had in this price range, too. Not saying it isn't worth it, but once you get up into this price range there are a lot of vintage amps to consider. I'm glad I have one, but I doubt I'd pay $900 to get one if I didn't.
     
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