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FDP Forum / Fender Amps: Vintage (before 1985) / '79 Champ

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darrengoleafs
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WNY

I played Black Sabbath at 78 speed
Dec 13th, 2017 09:46 PM   Edit   Profile  

Just picked up a '79 SF Champ. All original, quite minty just dusty. I really like it so far but wonder what a Weber sig8s would sound like?

Also, I think the original tubes are in it. Did Fender put wire around the tubes and under the socket mounting screws to hold the tube in place?

Peegoo
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but no guitar
Dec 13th, 2017 10:56 PM   Edit   Profile  

Unless the speaker is coming apart or buzzing, a speaker replacement isn't necessary. However, depending on what you have in there now (should be an Oxford, stamped with code 465XXXX), a replacement will probably be louder because the Webers are super efficient.

I think in 1979 Fender was not installing tube retainers on the rectifier (5Y3) and power tube (6V6). They may have 'bear traps' on them that hold the tube by the base because this was a cheap and simple mod many players did.

Wire? Sounds like kitchen-table amp tech-ery!

The pre tube (12AX7) should have a twist-lock aluminum can on it with a little spring in the end.

darrengoleafs
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WNY

I played Black Sabbath at 78 speed
Dec 14th, 2017 03:59 AM   Edit   Profile  

Honestly I like the sound of the stock speaker (which is what it is).

I will post a pic of the the ‘tube holders’ when I get a chance.

Thanks peegoo!

Peegoo
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Dec 14th, 2017 05:09 AM   Edit   Profile  

I have a '66 black and a '72 silver version of these. They are wonderful amps when cranked up.

I installed a bypass switch on the negative feedback loop on the '72 to make it sound more 'raw' for a raunchier tone--especially when used with a Green Bullet mic for harmonica.

The simple circuit of these Champs is what makes them such wonderful tone machines. Notes and chords should bloom and sound nice and glassy on decay.

If the amp sounds tired, suspect the tubes first; try swapping the pre and/or power tube. The rectifier tube generally either works or it doesn't. Next, check the filter caps; many deteriorate with age.

Remember that even these little amps can zap you if you go poking around in the chassis. Take all usual precautions as you would with a larger tube amp.

Bear trap tube retainers

(This message was last edited by Peegoo at 07:35 AM, Dec 14th, 2017)

darrengoleafs
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WNY

I played Black Sabbath at 78 speed
Dec 14th, 2017 05:59 AM   Edit   Profile  

"I installed a bypass switch on the negative feedback loop on the '72 to make it sound more 'raw' for a raunchier tone"

I did this on my Champion 600. Also put a Weber in it.

I will try the tube swap first on this SF Champ.
And maybe grab a couple bear traps as well.
added more pics in profile...

kitchen-table amp tech-ery!

(This message was last edited by darrengoleafs at 08:14 AM, Dec 14th, 2017)

Peegoo
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Dec 14th, 2017 01:10 PM   Edit   Profile  

Definitely not factory work!

darrengoleafs
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WNY

I played Black Sabbath at 78 speed
Dec 18th, 2017 07:27 AM   Edit   Profile  

Switched out the power tube for an EH I had around and it is a big difference! Also threw in a 5751 preamp tube. Still wondering about this speaker and if a Weber will be better.
What kind of 6V6 tube was in there (see pic above)? The base is shorter and I cannot tell from the markings. From wiki it is a 'coin' based 6V6 from the 70's. It sounded tired.

Bopper
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Motor City, USA

Better get hit in yo' soul
Dec 18th, 2017 08:28 AM   Edit   Profile  

"wonder what a Weber sig8s would sound like?"

I have an 8" Weber alnico Sig in a '65 Vibro Champ. I think it sounds really good.

Peegoo
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Curled up

in the fecal position
Dec 18th, 2017 09:03 AM   Edit   Profile  

darrengoleafs, that 6V6 looks like an RCA or GE 6V6GTA.

Like these, which are Fender re-brands.

darrengoleafs
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WNY

I played Black Sabbath at 78 speed
Dec 18th, 2017 09:15 AM   Edit   Profile  

Peegoo, yup. No Fender brand but the same grey 6V6GTA is there. Guess a bear trap wouldnt trap that.

Bopper, gonna give this tube swap a chance. It is louder with a good 6V6 and the Oxford is in good shape. The whole amp is.

carsten

on the rhine

Dec 18th, 2017 03:21 PM   Edit   Profile  

Hi darrengoleafs!

I´ve tried quite a lot of different speakers in various Champs - including original Oxfords, now and old Jensens - and Weber signatures, too!
I like the older speakers for their lively sound and, generally speaking, lower volume.
If you would like more volume and punch from your (Ch)amp a Weber signature-model is worth a try!
I personally preferred the smooth-cone over the ribbed-cone variant.

cheers - C.



Leftee
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VA

Life makes a man tired.
Dec 19th, 2017 05:42 AM   Edit   Profile  

I'll echo carsten's comments - right down to the smooth cone. I'll also add that you have to sonically beat on the Weber signature a few hours to get it righteous. IMO, etc.

(This message was last edited by Leftee at 08:50 AM, Dec 19th, 2017)

darrengoleafs
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WNY

I played Black Sabbath at 78 speed
Dec 19th, 2017 07:41 AM   Edit   Profile  

Thanks guys. Why smooth cone?
My thinking is ribbed. I put a smooth cone Weber in my Champion 600 when I modded that and have wondered about the ribbed ever since.

carsten

on the rhine

Dec 20th, 2017 04:18 PM   Edit   Profile  

Hi darrengoleafs!

I can´t really say "why"...
I just happen to own both (smooth and ribbed) - and the smooth-coned one sounds a tad fuller/sweeter to me.
It´s not a huge difference, though, and I might not even know (or care) if I didn´t have both ;-)

cheers - C.

darrengoleafs
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WNY

I played Black Sabbath at 78 speed
Dec 20th, 2017 06:50 PM   Edit   Profile  

Thanks carsten, "fuller/sweeter" makes sense. And FWIW, Weber is currently out of the smooth 8" sig. I think I will wait for now and get to know this amp with the Oxford speaker and some tube swaps.

darrengoleafs
Contributing Member
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WNY

I played Black Sabbath at 78 speed
Apr 6th, 2018 10:04 AM   Edit   Profile  

I am having an issue.

No sound. All 3 tubes light up but power tube is excessively hot!

Any ideas?

Hammond101
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So. Cal. USA

Apr 6th, 2018 11:46 AM   Edit   Profile  

Did the RCA speaker plug fall out of the chassis jack? I don't like that set up. Gravity tends to make it fail. Your amp may have it.

If plugged in you might want to test with another speaker. It may have failed. Measure the static resistance of the stock speaker voice coil to test.

You may have an issue with bias. That amp is cathode biased so this could mean the bias resistor or cap could have failed.

You may have a failing rectifier tube.

You may have a failed power tube.

If the '79 amp was not serviced and filter caps replaced the failure could be more serious.

Other than the speaker however, the other failures usually result in some noise(s)

It really is difficult to say unless the amp is on the bench.

darrengoleafs
Contributing Member
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WNY

I played Black Sabbath at 78 speed
Apr 7th, 2018 02:30 AM   Edit   Profile  

Thanks Hammond101! The rca speaker plug is a snug fit.
I replaced the pre-amp tube and viola! Could not tell by looking at it.
I had a 5751 Sovtek in there, now a 12ax7 EH...and more gain. Kinda prefer the 5751.

However, as stated earlier in the post, I must get either some retainers or new sockets. It is not moving at the moment but I do think the power and rectifier tubes would fall right out with not much effort.

Hammond101
Contributing Member
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So. Cal. USA

Apr 7th, 2018 03:46 PM   Edit   Profile  

See the tube socket clean and re-tension thread on the amp repair page. That will help. I'd add bear trap type retainers for the power and rectifier tubes.

If this thing has not been serviced I'd get those electrolytics replaced.

carsten

on the rhine

Apr 7th, 2018 04:05 PM   Edit   Profile  

Hi darren!

I also had tubes fall out of some of my Champs ;-)

But - you don't even have to get new tube-sockets! A good tech can clean and re-tension the old ones at a fraction of the cost.

Hope you'll get it up + running again!

cheers - C.

Next 20 Messages  

FDP Forum / Fender Amps: Vintage (before 1985) / '79 Champ




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