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Post subject: Champion 600 mods: where to start?
Posted: Sun Feb 05, 2012 5:50 pm
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I've had this little amp for a few weeks now and while I've really enjoyed it, it definitely has room for improvement, especially when it starts breaking up. The cleans are nice, but anything more than a slight crunch is just farty and harsh out of the stock speaker, and "woofy" out of my 1X12 Tweed Deluxe cab. lI've heard a lot of talk about replacing the speaker with a 6" Weber. I was also planning on getting some NOS tubes to replace the Chinese crap that came with it. Does anyone have recommendations for tubes that will pair up great with this amp without breaking the bank? And if you had to make a choice, which upgrade would you go with first - tubes, or the speaker?


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Post subject: Re: Champion 600 mods: where to start?
Posted: Sun Feb 05, 2012 6:56 pm
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How are you with a soldering iron and thin PCB (read: delicate) circuit boards? This amp has 400VDC rated coupling caps in it. I've put SBE 716P 600VDC into several. This really improves the tone response. And a silver mica in the tone-stack (C1, 250 pico-farad). Helps with that farting issue & cleans up the treble. Along with the Weber speaker (I use ceramic 6-inch) and re-doing the grille to a more tone-transparent one.

One trick that I do in replacing caps, is to clip the OEM caps right at the body. Then, wrap and solder the new caps onto the leads. That way you aren't pulling components off the board and overheating tracings. Use some heat shrink or teflon insulation to protect the wrapped leads.

Some ppl actually go to Mercury Magnetic trannies. You really got to want the amp to do this. As you'll never be able to sell the thing for the $$$ you put into it. Kinda like over-Hot-rodding an Acura RSX. Check YT link for demo. BTW... I own a 1948 Fender Champion 600 (5C1) and I have yet to find a RI that has it's Bluesy, great tone. And OD.

http://www.youtube.com/watch?v=zVGWICF5-i8


http://support.fender.com/schematics/gu ... ematic.pdf


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Post subject: Re: Champion 600 mods: where to start?
Posted: Sun Feb 05, 2012 9:57 pm
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Hmm... I'm decent with a soldering iron but I haven't yet had the nerve to really start messing around "under the hood" of tube amps yet. I am aware of the safety concerns of course and do have a buddy who's more experienced who could help me out. If something low-cost like replacing a couple caps is going to help, I'll definitely consider it. For now I may just stick with the less-invasive stuff. I just removed the speaker grille cloth and changed the preamp tube for a decent Groove Tubes one I had lying around. Unfortunately I did not have any 6V6s in my collection, but already this thing sounds WAYYY better. I'm going to order the Weber Ceramic Speaker, a NOS 6V6, and track down some lighter speaker grille material and see how I feel then. I totally agree with your car analogy. I don't expect the world out of this amp. It has to be one of if not the cheapest all-tube combos out there, and in a lot of ways it shows. I'm really going to resist the urge to spend a lot of money on something I will never gig with, but if I can do a couple things here and there to make the amp's full range useful and make it more satisfying to practice on, and keep the total budget under, like $225, that would be awesome. I thought it was a neat little amp when I tried it out in the store, but it's just inevitable that whatever I get my hands on, whether it's a guitar, amp, car, motorcycle, etc - I'm going to mess with it. Just can't help it.


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Post subject: Re: Champion 600 mods: where to start?
Posted: Sun Feb 05, 2012 11:17 pm
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ExiledonMainSt wrote:
I've had this little amp for a few weeks now and while I've really enjoyed it, it definitely has room for improvement, especially when it starts breaking up. The cleans are nice, but anything more than a slight crunch is just farty and harsh out of the stock speaker, and "woofy" out of my 1X12 Tweed Deluxe cab. lI've heard a lot of talk about replacing the speaker with a 6" Weber. I was also planning on getting some NOS tubes to replace the Chinese crap that came with it. Does anyone have recommendations for tubes that will pair up great with this amp without breaking the bank? And if you had to make a choice, which upgrade would you go with first - tubes, or the speaker?


A good place to start is my thread:

viewtopic.php?f=13&t=63259&hilit=Champ+600

:D

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Post subject: Re: Champion 600 mods: where to start?
Posted: Mon Feb 06, 2012 1:12 pm
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bluesky636 wrote:
ExiledonMainSt wrote:
I've had this little amp for a few weeks now and while I've really enjoyed it, it definitely has room for improvement, especially when it starts breaking up. The cleans are nice, but anything more than a slight crunch is just farty and harsh out of the stock speaker, and "woofy" out of my 1X12 Tweed Deluxe cab. lI've heard a lot of talk about replacing the speaker with a 6" Weber. I was also planning on getting some NOS tubes to replace the Chinese crap that came with it. Does anyone have recommendations for tubes that will pair up great with this amp without breaking the bank? And if you had to make a choice, which upgrade would you go with first - tubes, or the speaker?


A good place to start is my thread:

viewtopic.php?f=13&t=63259&hilit=Champ+600

:D


Great thread! Thanks, this should definitely come in handy. I think I'm going to pick up some Oxblood grille material, but for now I just used some black mesh from a bag I had around. It's not perfect, but I do think it looks a lot better than the faux-suede. When I flicked the original speaker cloth with my finger, I could hear it flap around, so I can definitely see how that would be part of the "fartiness" when cranked. Sounds much better now - a little bright with single-coils, but I'm hoping some better tubes and the Weber Ceramic speaker I have on order will fix that.

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Post subject: Re: Champion 600 mods: where to start?
Posted: Mon Feb 06, 2012 3:26 pm
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ExiledonMainSt wrote:
bluesky636 wrote:
ExiledonMainSt wrote:
I've had this little amp for a few weeks now and while I've really enjoyed it, it definitely has room for improvement, especially when it starts breaking up. The cleans are nice, but anything more than a slight crunch is just farty and harsh out of the stock speaker, and "woofy" out of my 1X12 Tweed Deluxe cab. lI've heard a lot of talk about replacing the speaker with a 6" Weber. I was also planning on getting some NOS tubes to replace the Chinese crap that came with it. Does anyone have recommendations for tubes that will pair up great with this amp without breaking the bank? And if you had to make a choice, which upgrade would you go with first - tubes, or the speaker?


A good place to start is my thread:

viewtopic.php?f=13&t=63259&hilit=Champ+600

:D


Great thread! Thanks, this should definitely come in handy. I think I'm going to pick up some Oxblood grille material, but for now I just used some black mesh from a bag I had around. It's not perfect, but I do think it looks a lot better than the faux-suede. When I flicked the original speaker cloth with my finger, I could hear it flap around, so I can definitely see how that would be part of the "fartiness" when cranked. Sounds much better now - a little bright with single-coils, but I'm hoping some better tubes and the Weber Ceramic speaker I have on order will fix that.

Image


The Champ 600 is super easy to mod. The schematic is simple and easy to read. The circuit board has all the parts labled. Heck, a caveman could modify it.

After completing my Champ 600 mod, I went on and built this:

viewtopic.php?f=13&t=65668

I had an advantage with that one, though - I have an electrical engineering degree. :lol:

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Post subject: Re: Champion 600 mods: where to start?
Posted: Mon Feb 06, 2012 3:32 pm
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Here's another step-by-step Net page. You buy the caps (silver mica & SBE OD's or Mallory-150), online for a LOT cheaper than buying the "kit."


http://www.specialtyguitars.com/champ-kit-install.html


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Post subject: Re: Champion 600 mods: where to start?
Posted: Mon Feb 06, 2012 3:42 pm
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BMW2002Ti wrote:
Here's another step-by-step Net page. You buy the caps (silver mica & SBE OD's or Mallory-150), online for a LOT cheaper than buying the "kit."


http://www.specialtyguitars.com/champ-kit-install.html


All that does is replace the tone and coupling caps. It keeps the tone stack in place. Removal of the tonestack completely results in the best sound IMHO.

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Post subject: Re: Champion 600 mods: where to start?
Posted: Tue Feb 07, 2012 6:02 pm
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bluesky636 wrote:
BMW2002Ti wrote:
Here's another step-by-step Net page. You buy the caps (silver mica & SBE OD's or Mallory-150), online for a LOT cheaper than buying the "kit."


http://www.specialtyguitars.com/champ-kit-install.html


All that does is replace the tone and coupling caps. It keeps the tone stack in place. Removal of the tonestack completely results in the best sound IMHO.


After watching a couple youtube vids, I definitely want to delete the tonestack. You mention it makes the amp more gainy. Is the clean volume still as loud as before, just lower on the volume knob?

I did find a store that sold single JJ 6V6s, so I have now replaced both tubes. Holy crap - huge difference! My Ibanez ES-335-esque guitar with 'buckers now sounds GREAT out of this amp. Surprisingly full, clean jazzy tones with the neck, nice Keith-ish rhythm tones with both, and nice classic rock overdrive with the bridge. I have this guitar wired with the "50's-style" Gibson wiring, and when I roll of the volume the amp responds perfectly - stays loud, just cleans up.

My Strats are another story, however. Still have the "icepick" syndrome. Ugh. Sounds like a toy. I can't wait for the Weber Ceramic speaker I have on order to get here, although I'm kinda thinking of pillaging the 8" speaker from a solid-state Vox combo that's currently in pieces in my basement, and creating a new baffle for it.


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Post subject: Re: Champion 600 mods: where to start?
Posted: Tue Feb 07, 2012 7:08 pm
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Removal of the tonestack completely...

Thanks! I'll have to try this mod on a RI Champion 600. This amp definitely needs something. As none I've tried even comes close to the original Champion 600. IME.

This mod will definitely improve the gain and OD. I've done this to SFVC (AA764). I actually revert the circuit to a 5F1 (lower global feedback voltage, 22k-ohm replacing 2700 ohms) and lower plate voltage onto the input tube (22k-ohm in PS rail replacing the 10k-ohm one). You get a much browner, slower onset of OD. More Bluesy. And the extra 12AX7 (for the vibrato section) adds a different flavor to the amp, than the single 12AX7 of a 5F1.


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Post subject: Re: Champion 600 mods: where to start?
Posted: Tue Feb 07, 2012 10:06 pm
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ExiledonMainSt wrote:
After watching a couple youtube vids, I definitely want to delete the tonestack. You mention it makes the amp more gainy. Is the clean volume still as loud as before, just lower on the volume knob?


Yes.

I just leave my 600 set to "12" and control teh volume with the guitar. Gies from nice and clean to thick overdrive. If I really want nasty, I just hit it with a Electro-Harmonix LPB-1. I'll try to make a sound clip in the next week or so.

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Post subject: Re: Champion 600 mods: where to start?
Posted: Tue Feb 07, 2012 10:10 pm
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BMW2002Ti wrote:
Removal of the tonestack completely...

Thanks! I'll have to try this mod on a RI Champion 600. This amp definitely needs something. As none I've tried even comes close to the original Champion 600. IME.

This mod will definitely improve the gain and OD. I've done this to SFVC (AA764). I actually revert the circuit to a 5F1 (lower global feedback voltage, 22k-ohm replacing 2700 ohms) and lower plate voltage onto the input tube (22k-ohm in PS rail replacing the 10k-ohm one). You get a much browner, slower onset of OD. More Bluesy. And the extra 12AX7 (for the vibrato section) adds a different flavor to the amp, than the single 12AX7 of a 5F1.


Yeah, I redid my Champ 600 to 5F1 configuration. I tried replacing the 10K resistor with a 22K resistor and did not like it. It lowered the gain too much for my tastes.

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Post subject: Re: Champion 600 mods: where to start?
Posted: Tue Feb 07, 2012 10:40 pm
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Blue, did you try changing the GNFB resistor from stock 2.2k-ohms (R7) to 22k-ohms? This resistor should go right to pin 8 of the 12AX7. And not the crazy voltage divide past the cathode tied network to ground. See the original 5F1 schemo.

This 10X difference really lets a good 12AX7/6V6GT shine. Should be done with plate voltage drops to the 12AX7. The lower feedback voltage allows for greater voltage swing in the 12AX7. And slower, earlier onset of OD in the 6V6GT.

YMMV, of course.

http://support.fender.com/schematics/gu ... ematic.pdf

http://www.webphix.com/schematic%20heav ... _schem.pdf


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Post subject: Re: Champion 600 mods: where to start?
Posted: Wed Feb 08, 2012 5:30 pm
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Yes, I changed the feedback circuit to the 5F1 configuration. With the exception of keeping the power supply stock and leaving the 6V6 grid stopper and screen resistors in place, my Champ 600 is built to the 5F1 circuit. I may experiment some more with the power supply once I get my5F6A tweaked to my liking. :D

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Post subject: Re: Champion 600 mods: where to start?
Posted: Thu Feb 09, 2012 7:33 am
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Here I am being bad again, same subject just not a fender product.

I just bought a VHT Special 6 Head just to take apart and make my own little tweed champ.

Any of my fine friends here dig into one of these yet ?

I wanted the head so i could have two 1X12 cabs one alnico and one ceramic

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