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NAD...'64 Champ. Too clean!

capnjim

Senior Member
Messages
1,228
So I just picked up a really nice, all original little champ. It has a Jensen P8R 4ohm in it. The thing is, I was expecting a bit more volume and crunch. I tried swapping the power tube but there was no difference. Its not really very loud either.
Aren't these guys supposed to get a bit crunchy? Its sounds great, very clean, but I wanted that tubey crunch. Anything else I can check? Any simple mods to make it break up a bit earlier? Right now its clean unless its dimed, then its distorted, but not in a pleasant way. It came with the original speaker in a box, would it be worth trying it out?
Thanks
 

SamBooka

Member
Messages
2,222
I think I know the problem jim. The BFs are collectible but really you need a 77 SF with a Weber Sig 4 Alnico to get tone nirvana. Because you are a nice guy I would be willing to do a straight trade.. but dont tell anyone. I can be at your place in 30 min lol.

Ok.. seriously. Avoid the original speaker (keep it safe in the box).
BFs dont roar like the tweed ones but you should get a nice Stonesy crunch out of it (a little dirtier than Brown Sugar unless your are using a humbucker or something hot)
I know you know fenders well but it almost sounds like you are plugged into the low in.
Check the input jacks are shorting out properly. Other than that it is the usual suspects : Dirty contacts. Bad tubes. Bad caps.

Enjoy.

Drew
 

'58Bassman

Member
Messages
4,928
So I just picked up a really nice, all original little champ. It has a Jensen P8R 4ohm in it. The thing is, I was expecting a bit more volume and crunch. I tried swapping the power tube but there was no difference. Its not really very loud either.
Aren't these guys supposed to get a bit crunchy? Its sounds great, very clean, but I wanted that tubey crunch. Anything else I can check? Any simple mods to make it break up a bit earlier? Right now its clean unless its dimed, then its distorted, but not in a pleasant way. It came with the original speaker in a box, would it be worth trying it out?
Thanks
What rectifier is in it? If it's a Sovtek, get a real one. The Sovtek don't drop the voltage the way old rectifier tubes do, so you'll get no crunch with a Sovtek. It will be loud, clean and annoying. I had a '66 that bever broke up the way I wanted until the night before I shipped it to the buyer- I listed it as having an old 5Y3G ("Coke bottle" tube) and that's not what had been in it the whole time I wasn't getting the sounds I wanted. Sure enough, I fired it up with the old 5Y3G and it never sounded better. The buyer was blown away by it, too.

Are you using single coils, or humbuckers? It will break up a lot sooner with humbuckers.

Also, don't just haul off and change the bias just because a bunch of people tell you to. I made that mistake and hated it. I measured the voltage and did the calculations to find a value that worked much better.
 

capnjim

Senior Member
Messages
1,228
I didn't try changing the rectifier. Its an old RCA 5y3 and the power tube is the matching 6V6. I changed the power tube for a new JJ 6V6 and there was no difference. It will break up very slightly with humbucker on 6 or so, but with my strat its clean all the way. I probably have another 5Y3 somewhere and I'll swap it out just to see, but I doubt it will make any difference.
I'll take it out and look at the input jacks, but the low is lower than the high and they seem to be working. I can live with it the way it sounds now, I tried it with my modded Blues driver and it sounds awesome.
Thanks guys.
 

bschultzjames

Member
Messages
1,231
I've noticed that putting a 10" speaker in these works really well. A friend of mine has a SF Vibrochamp that he put at 10 in and it instantly turned into a giant sounding small amp. You'll need to change the baffle though or *gasp* cut into the baffle to fit a 10 correctly.

It sounds like you may need to give the amp a cap-endectomy too, change out the old caps as was mentioned earlier.

I'm in the process of building a new baffle out of pine and aged black sparkle grill cloth to install an old Jensen p10r for my '69 vibrochamp. I'm sure I'll post a new thread with photos of the before / process / after stages of the modifications.
 

redeyedjim

Gold Supporting Member
Messages
2,347
I have a 66 BFVC for what it's worth, and yes, these little Champs can get exactly the crunch you want with fresh caps, a good 6V6, and the right speaker. Sometimes, though, they'll also need a new OT, and occasionally a PT. Mine needed both, and was much better after the new parts tuneup.

I did the 10" speaker upgrade on my BFVC (still auditioning speakers, but currently like the Weber 10A150) and thought it improved the amp significantly over what it was before. Some folks feel this is heresy, others feel it is the right thing to do. You have to decide for yourself what you want this little amp to do, but I'll tell ya, with a 10" speaker it will do a lot more.

As a headsup/public service: There is a TGPer selling a 4 ohm Weber 10A100 (20w, undoped) and 10" Champ baffle (bare, no grill cloth) in the Emporium now. He wants a low price for these. I am not the seller, nor am I related to the seller in any way. But this is a good upgrade path, in my experience, and will give you a very pleasant sounding Champ.

Final thought: after doing a bunch of tube rolling on mine, I really fell in love with the sound of the vintage HyTron 6V6GTY tubes. These were sold under various brands -- CBS seems to be a popular one -- and they bring a very nice power tube crunch to the whole affair. And they are fairly cheap on eBay -- less thasn $30, in most cases. They also take over voltage very well, which is good because a lot of Champs are biased very hot.

HTH in some way.
 

capnjim

Senior Member
Messages
1,228
Thanks, I'll do a cap job and play around with tubes, but I like the speaker and want to leave it stock. Its actually got that great blackface clean sound and take pedals really well. Maybe fresh caps will help a bit. Just for the heck of it, I'll also throw in the original speaker and see how it sounds. The Jensen in new so maybe it also needs a bit of breaking in too.
 

mrface2112

Member
Messages
2,047
Blackface (and Silverface) Champs are not exactly distortion generators. They get a little crunchy when dimed, but that's about it. I've got a '66 Champ, had a '76, and still have a '69 and '74 Vibro Champs. None of them get very overdriven.

The Champs that tend to be distortion generators are the Tweed Champs, which are completely different animals from their black and silverface counterparts.

If this '64 Champ sounds great (albeit not as overdriven as you'd like), don't mess with it! Certainly don't go changing the PT and OT and whatnot. Leave it alone.

My advice would be to get a nice stompbox to provide your dirt, or look into a Tweed Champ (5F1) or Tweed Deluxe (5E3).


cheers,
wade
 

capnjim

Senior Member
Messages
1,228
Thanks Wade, I'm going to change the filter caps and thats it. I have my EH nano reverb and modded Blues driver hooked up and it couldn't sound any better. I'm actually selling my '68 Princeton Reverb as they sound almost identical. Its a great little mini-blackface amp!!

I might even stick back the original speaker. It has a much bigger magnet than the new Jensen and it might give me back that little touch of low end its missing. Its not missing enough that I'm going to go through the bother of making a new baffle and installing a 10" speaker. I'm just curious as to how the original speaker will sound.
I love it!!
 

capnjim

Senior Member
Messages
1,228
Its a '64 blackface. One of the first ones I guess. Bass and treble controls, says Fender Electric instruments co. on the panel. Not Fender Musical Instruments. Also, the trannys have '64 date codes.
 

teleman1

Silver Supporting Member
Messages
15,478
Capnjim, I think you have nailed your situation on the head. It's like a PR,especially the clean. The only thing you might be able to do is remove the negative loop????something like that. My friend had it done to a clean Gibson amp; great clean and one flick of the switch and Tweedville arrived. Maybe that would work for you, you wouldn't be giving up anything and its alterable. If you want to give yourself a treat, put an 8 inch preferably the one you have in a 1x8 cab,(hit me up if you want the dimensions), but that cab makes the speaker blossom like it can't in a Champ combo. The special design 8 inch alnico Jensen has a great soloing sound. A little farty on chords or I need a tube..
 

capnjim

Senior Member
Messages
1,228
Thanks tele, how do I remove the negative loop? I don't mind soldering a little here and there.
 

Prattacaster

Member
Messages
1,369
There will be a yellow wire connected to your speaker jack that isnt your OT. This wire will sneak under your board and go to a 2700ohm resistor that is mounted on the board. Disconnect the wire at the speaker jack. Grab a DMM and check for continuity between the unsoldered end and the 2700ohm resistor, just to be sure you've disconnected the right wire. Put a little heat shrink on the unsoldered end. Play.

If after you recap, you find your B+ voltages are a little high one mod you can do is add a dropping resistor between the rectifer and your first filter. This is actually much easier in practice that it sounds. You uninstall the red wire coming off of Pin 8 on the recto socket. The other end goes to the very first eyelet on the board; at the 1k resistor right in front of the power tube. The first filter also connects here.

Once you have the wire uninstalled your ready to put in a 10w resistor. What value?? Well that depends on the B+ at the recto socket, you did take note of that right? I usually shoot for around 350-360vdc at the 1K resistor. It will most often be a 200ohm-300ohm 10w resistor. Adding this resistor always soften up those bright and clean BF and SF champs. The resistor will be installed point to point since its long enough. Thats is recto Pin 8 to 1k resistor. In short you are replaceing this wire with a resistor.

Another thing that would lose you some gain are your cathode bypass caps of course. These dry up and then your gain stages are no longer bypassed or partially so.

Like someone mentioned a weak preamp tube could be the culprit, could be all the above.
 

teleman1

Silver Supporting Member
Messages
15,478
Thank Prattacaster to fill in the void of my lack of electrical experience, but that's what I was speaking about.
 

teleman1

Silver Supporting Member
Messages
15,478
Prattacaster I heard the difference in a Gibson RV-19???Had a bunch of 6eu7's in it. Anyway, it was of those oldies that was clean up to 10. Beautiful, but no breakup.Added the neg loop mod and wahla! a little tweed monster was inside there.
 




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