Showing Off: 5C1 Champ Extra Fancy Grade

[rp]

My first all octal and it works just great. For the life of me l would never have found that 5V CT snafu if not for TAG community. I would have assumed I messed up the PT when I took the bells off and I would have pulled it all part. Long Live TAG.

I think it's the quietest tube amp I've ever come across, ss quiet and so much for my octal fears. Go PTP and Buss Bar if you want quiet. I was impatient to finish and just drilled out for the Edcor OT rather than wait and test it externally. I don't have money anyway to start rolling OTs even little Champ ones. And yes the Edcor is an achingly clean, clear, detailed, non-saturating OT. If it's not the best for this application I don't want to know anymore, but I'm liking what I hear, love the detail, and it looks pretty.

https://picasaweb.google.com/1041232856 ... directlink

My voltages are silly close to the schematic, they are posted at the bottom. That is a good sign.

It has much less gain than my 5F1 @370V. I used old coupling caps and they could be leaking DC but the sound and voltages indicate all's OK and no scratchy pot. As I have a 5F1 I'm good with the gain issue, but I have to hit the strings harder and work harder than I like. This is not an amp on the edge that wants to swell up and that you have to work to control it, the opposite - you have to work to drive it. It's a great bedroom amp, even the 5F1 will eventually make my ears ring and bring on the neighbors, the 5C1 doesn't but still rocks and is fun to play. I can get a gain boost with a 5V4 but the sound gets harsher. It rocks harder but sounds more generic, I need to test this more as I get to know the amp.

I notice there is very little going on on the VOL pot btw 0-2 o'clock, it's so low gain below 2 o'clock as to be useless even for cleans. Is it the PEC's taper? Did AES send me a linear instead of an audio? If people tell me the PEC has a noticeably smoother more linear-like taper than an Alpha I'll swap it right out.

The little table top hi-fi set-up is the best platform ever for tube rolling. Real easy and nothing gets too hot, tubes cool off in a few minutes. I've been trying tube permutations, all sound different, all fun to play, and it's hard to choose - that's a good sign of the amp's overall validity.

My original big bottle set up with the red 5693 seems the lowest gain, cleanest, chimiest, twangiest, sounds more Voxy, the 6SJ7 more '70s Marshally. Hard to choose btw the 5693 vs 6SJ7. The former provides a bit more clarity and headroom, it's more strident, the later dirtier and smoother with more grind.

The metal envelope 6V6 is for this brief test my fave, the most bite, the crunchiest with more clang - a bit closer to its tweed origin, though this amp still does not sound tweed but sounds 70s-80s British.

Overall the amp has a tighter detailed more modern sound than I expected. I hear the modernness in the bass where it's a bit buzzier less organic than vintage but I need to let the filter caps burn in longer to get rid of that congested sound when they're new, I'm already hearing a big improvement every few hours. On power chords it has more clang than a Fender - more like a tiny Hiwatt. I also hear the moderness in the single note clarity and detail, even played flat out it's notable. The clarity cuts right through the distortion, crystal clear with bite but no ice pick, so I can accept this. For single note work and picked out rock chords it's very appealing for a tiny amp. I'm pretty sure the clang and clarity are the big M6 OT's doing. This 5C1 takes my Boss DS-1 much better than a 5F1 where a pedal to me is redundant and useless. With the DS-1 (gain up, distortion down, like a boost) it sounds like a little high-gain amp - like a JCM800. I like more loose organic amps, but I got those so this is OK.

I also noted two things. I prefer it with an old Whirlwind Belden cable than with my Mogami and Canare - sounds more even and warm. I also changed out the ww 500 CR for a 2W cc 470 for no good reason and it seems a little warmer like with the cable. I don't see how the CR could make a difference, it could just be more break-in progress I'm hearing or wall voltage changes. I had a few complaints when I first plugged in but as it breaks in and I get to know it I'm really grooving it. Sounds nothing like I expected but sounds really good. Polite vicious rather than tweed raucous madness.

If anyone who is familiar with the 5C1 and/or octal pentodes, grid-leak bias, etc can report back if the design is inherently much less gainy than the 5F1 I'm very curious to know. If you have a real one I'd love to hear back how it compares to mine.

Any ideas how to get a little more swell (without drastic changes) or is this a limitation of the low 300V plate V?

BTW speakers were the old Canadian Jensen EMC 10" in my Harvard clone and the same type in a 15". The 15" with the 5C1 sounds really fine.

[Colossal]

Man, that is a fine looking amp. I love everything about it from the killer old school tubes to the lacewood (?) side caps on the chassis. Painted end bells to boot. Great job. Love the PTP layout, very clean. I know what you mean about the clang and I agree it's that monster OT. I'll bet it sounds big, articulate, with great clarity for such a small amp.

[Cliff Schecht]

Looks great! You are spot on in thinking that the unsaturated transformer sounds better than a saturated one for Champs. I think they sound wimpy with an underrated transformer and ballsy with a properly rated one.

[martin manning]

Very nice indeed!

[jon]

I love all octal single enders. Your is very beautiful.

[surfsup]

Very nice! Surprised you feel the busbar is quiet, I thought the opposite and also read many posts the bussbar is finicky. I'll take a closer look at your pics

[Big Jim]

Nice looking build! I will have to try my hand at a point to point one of these days. These little circuits seem like a logical place to start. Well done. Sound clips???
Jim

[FunkyE9th]

Nice! The table top setup is a great choice for showing of those tubes and xformers.

[Phil_S]

Very nice! Surprised you feel the busbar is quiet, I thought the opposite and also read many posts the bussbar is finicky. I'll take a closer look at your pics

Grounding is all about understanding low potential vs high potential parts of the circuit. When using a buss ground, you must get the order of placement and general placement on the buss correct. There is no one system of grounds that is inherently better than any other. None of them work right if you don't know what you're doing. All of them can be made to work right. Sometimes, people make compromises for assorted layout considerations that may or may not work well. Building an amp free of ground-related hum is not so hard to do, but you must understand what you are doing.

There is nothing more or less finicky about buss bar than any other system of grounds. It is up to the builder, not the buss! My personal experience is that I really like the buss bar for it's convenience. That doesn't mean you slap the ground wire onto the closest spot on the buss.

[rp]

Colossal, it's cherry, with some figuring but the top edges have this lovely busy silking that probably makes you think its lacewood.

Regarding the buss bar I use it first to tie things to and avoid an other terminal strip that would then have to go to ground anyway - less connections. Half the connections in an amp go to ground so this really cleans things up and it's hard enough working on a PTP amp. When I first laid out an amp this way I was playing around with terminal strips on a 1:1 scale drawing when I realized I didn't need half of them if I ran a buss.

I group things on the buss starting at V1 where I ground the bar to the chassis. Then V2, V3... etc down the buss, Power Section at the other end w/ everything in their own group on the buss. If something is far away like a pot or filter cap I'll run a black wire to its stage on the buss. I don't technically know what I'm doing but all my amps are super quiet so I guess it works. I do know with electronics you can't go wrong with clean, orderly and short.

I wasn't crazy about this amp at first but it's loosened up and I've been playing with it a lot - a good sign. It's not a Champ of any type, it's some sort of mini-me Hiwatt / JTM50. I can get real piano like tones backing down a touch on the volume - Beautiful late night sounds, it really grabbed a hold of me late last night. Sounds like MC5 or Townshend when hit hard or with power chords. Funny little amp. The Edcor is crystal clear and hifi as I predicted but it's cool. There is that touch off buzziness on the bass that in my experience comes from too fancy OTs but I can mitigate it w/ speaker and tubes. My 5F1 also has a burly Allen OT but it's not clear like this and still sounds like a Champ. I believed using all cc and old caps saved my ass. I think it would have been ice pick hell with mf and orange drops.

I dig the metal 6V6 best - brings out the hiwatt quality more, the ST tube is looser and more harsh. I usually get tired fast with tube rolling but this makes it fun and it's very revealing - again I think its that OT.

No neighbors have complained so I needed this amp!

[ToneMerc]

Very nice! Surprised you feel the busbar is quiet, I thought the opposite and also read many posts the bussbar is finicky. I'll take a closer look at your pics

Grounding is all about understanding low potential vs high potential parts of the circuit. When using a buss ground, you must get the order of placement and general placement on the buss correct. There is no one system of grounds that is inherently better than any other. None of them work right if you don't know what you're doing. All of them can be made to work right. Sometimes, people make compromises for assorted layout considerations that may or may not work well. Building an amp free of ground-related hum is not so hard to do, but you must understand what you are doing.

There is nothing more or less finicky about buss bar than any other system of grounds. It is up to the builder, not the buss! My personal experience is that I really like the buss bar for it's convenience. That doesn't mean you slap the ground wire onto the closest spot on the buss.

Amen!

[rp]

Thought I'd update for others interested in the 5C1.

I jumpered-in the Triode Champ OT. Ugh, blah, muddy one dimensional sound. Amp sounded like a generic little SS amp with the distortion up. The Edcor killed it. I'm glad I revolved that issue. I'm not 100% down on the Edcor, it makes the amp a little too crisp and modern sounding, but I did some research and I now think the 5C1 grid-leak circuit combined with the Edcor accounts for politeness and the modern overdrive sound.

Here's some info I found on the net and it jibes closely with what I'm hearing.

I've worked on guitar amps having an input stage that is grid leak biased pentode. The first time coming across it made me think WTF? They sound really clean lightly driven and produce a unique sounding distortion when driven hard.
http://www.diyaudio.com/forums/tubes-va ... des-2.html

THD Flexi head. In the article they interview maker Andy Marshall and he mentions that the first stage of the amp is set up with grid leak bias..."I chose grid-leak biasing both for its very high input impedance and the 'feel' it provides. The higher impedance makes for a much more sensitive input, which, in turn, allows you to more easily discern subtle differences between pickups, effects, and cables. The feel-factor of the grid-leak stage is due partly to the asymmetrical nature of its commpression. It's quite lovely, and it makes for very fat-sounding clean tones and rich, complex overdrive."
http://archive.ampage.org/threads/6/gag ... ues-1.html

Played it all weekend, I like it a lot. Power chords are restrained but the tone is like a Hiwatt or JTM50 and doesn't irk the neighbors. It's a really fine bedroom amp. Better than a 5F1 which is louder and looser. My friend was playing jazz chords through it and it was beautiful, not much gain clean but lovely 2AM sound. I tried it though a Celestion V10-60 and got a lot more volume, but I preferred the tone of the old Jensen. Now I need to find the proper speaker for it that'll give me the right tone and a bit more volume.

And my fave tubes now are the 5693 / 6V6G. Thanks for all the kind comments.

[rdjones]

Congrats on the amp, it would have been a shame for it to be sent back to the parts bin

Thanks for the report on the amp and for giving so much circuit observations and playing impressions.

You know ... I'm not a real big "Single Ended" type guy (or octal preamp either) but with so much SE being tossed around lately (like RJ's projects especially) I might have to take a look for myself.

rd

[rp]

Little update: I checked my coupling caps and the 2 seeing the B+ are good, no dc leaking. I couldn't test the red Pyramid grid leak cap but I swapped it out for a modern Kimber cap I had. This made a pretty serious difference, just a bit more of everything tone-wise, gave the amp a bit of a kick in the butt. Seeing how the guitar is going straight through this maybe putting a 50 year old pull here wasn't the best idea.

Tried it with a WGS Vet 10". What a sound! The 5C1 is great. I tried the speaker with the 5F1, great too. Fine speaker for a Champ. Not super loud but what a rich tone - crunchy, warm, but bright and alive.

[HTH]

nice build - I've got a 5C1 build here myself, well, sorta. its started out as a 5C1 with grid leak biased 6SJ7 and 6V6 (ss rectified). now it has a grid leak first stage and cathode biased second stage using a 6SL7 (which I like better).

my little amp also has a line out feature and a 25w wirewound to take the load with no speaker connected - used like this, you can run the amp as an overdrive unit into the front end of another amp. try it with your 5C1 into the 5F1, might find something you like.