$200 Champ

[Totally bored]

Just picked this cute little baby up for $200. These Forums give me amp gas and I think I'm a littlle out of control. At least I'm into cheap stuff ?
It works and sounds decent. Somebody stuck a 6L6 Power tube in there so I removed that and plopped in a RCA 6v6 greyplate that I had laying around. Amp also has a RCA rectifier in there. I'm assuming that it's a 5y3 ? There are no markings on it so ?





Chassis shot




Looks like someone had worked on the amp at one time by the 2 Power resistors and 1 cap that appear to have been changed. I'm trying to figure out if these values are what I want in there or should I put the stock values back in. Maybe someone did a worth while thing or maybe not ?



Also, theres a little cap on the the Power Tube, whats up with that ? Don't see that on the schematic.

[Totally bored]

So after a little bit of Google-ing I think this amp is a 1974.









Anybody have any thoughts on those Power resistors and the 1 changed cap and the one cap the Power tube ?

[Mesotech]

I'd say a good score! From the choke and power transformer codes and other cosmetics, I'd place the amp as a mid year 1974. The cap across the power tube, I'm not quite certain, but I've read somewhere (and can't find the reference now) that it was added by Fender to solve some noise issue, but in reality sucks tone. If I recall correctly, the advice in my misplaced reference said to clip it out of circuit. Don't try this without confirmation from others though.

Champs can be very fun amps, and are not the "toy" they appear to be. There is serious tone to be had from these little guys. Connected to a 4x12, they can bark like a big (ok - medium) dog.

Edit to add, the power resistor and cathode cap appear to be replaced (but you knew this). The resistor was replaced with a carbon comp resistor and the cap was replaced as part of the proverbial "cap job" that everyone talks about. The new cap is fine, the carbon comp resistor is fine also. The change in value of this filter circuit can alter the way the tube amplifies, either by making it cleaner than before (not a typical mod) or by making the tube distort asymetrically (an often desireable mod). Unless you drive the amp hard, you most likely won't notice the difference, as it can be subtle unless you knew how the amp sounded before.

[Cygnus X1]

Very nice!
You did well for the money-the cosmetics justify it alone.

[javlib]

The first picture shows an orange thread (from what I see) in the grill cloth and that would indicate 1976-1980

[juniorspecial]

Wow! I didn't know those came with a remote!

[phantomman]

The tranny code "606-4-13" pegs it as the 13th week of 1974, which is consistent with the orange-grille cosmetics.

Nice score!

[Totally bored]

I'd say a good score! From the choke and power transformer codes and other cosmetics, I'd place the amp as a mid year 1974. The cap across the power tube, I'm not quite certain, but I've read somewhere (and can't find the reference now) that it was added by Fender to solve some noise issue, but in reality sucks tone. If I recall correctly, the advice in my misplaced reference said to clip it out of circuit. Don't try this without confirmation from others though.

Champs can be very fun amps, and are not the "toy" they appear to be. There is serious tone to be had from these little guys. Connected to a 4x12, they can bark like a big (ok - medium) dog.

Edit to add, the power resistor and cathode cap appear to be replaced (but you knew this). The resistor was replaced with a carbon comp resistor and the cap was replaced as part of the proverbial "cap job" that everyone talks about. The new cap is fine, the carbon comp resistor is fine also. The change in value of this filter circuit can alter the way the tube amplifies, either by making it cleaner than before (not a typical mod) or by making the tube distort asymetrically (an often desireable mod). Unless you drive the amp hard, you most likely won't notice the difference, as it can be subtle unless you knew how the amp sounded before.

Thanks, thats the info I was looking for.

I quess I'll leave them Power resistors and cap alone then. Forgot to mention that the Cap can looks to have be replaced at sometime also. I think my 72 DR had the same cap across the Power Tube and I clipped that way back when so thats what I'm gonna do.


$200 bucks and no maintenance required. I'm jiggy with that.

[Totally bored]

The tranny code "606-4-13" pegs it as the 13th week of 1974, which is consistent with the orange-grille cosmetics.

Nice score!

Thanks

I did kinda notice a little orange in there, Wierd ! No rips on the the clothe and Tolex so I'm leaving her alone. The photo is not a got shot but even the Silver Panel is nice and clean.

[phantomman]

Nice and clean is an understatement, TB. It's a beauty!

I jus' picked up an '80 Princeton in about the same state. I'm gonna have a new pine enclosure built for it though -- it has the original MDF cab wif blue-stripe grille cloth but I'm gonna "back-date" it a bit by going with the metallic turquoise stripe. I'm also having the baffle cut for a 12-inch driver......I know that somewhere -- out there -- there's a JBL D-120F lookin' for a home.

[stratcat55]

That's a great deal. I paid $150.00 for my 74 about 12 years ago.
Congrats!

[Don]

Why do you think the cap can looks replaced? The solder looks original in the pics.
If it hasn't been replaced, replacements are available and it's an easy job (I put one in my Princeton Reverb last year).

[Totally bored]

Nice and clean is an understatement, TB. It's a beauty!

I jus' picked up an '80 Princeton in about the same state. I'm gonna have a new pine enclosure built for it though -- it has the original MDF cab wif blue-stripe grille cloth but I'm gonna "back-date" it a bit by going with the metallic turquoise stripe. I'm also having the baffle cut for a 12-inch driver......I know that somewhere -- out there -- there's a JBL D-120F lookin' for a home.

Love my PR. I made a baffle for mine cheap. Baltic Birch Plywood from Home Depot. Cut out 12" hole then painted in flat black and stuck some grill clothe over it. Still have the original with the 10" mounted on it for quick easy change outs.

Consider a Celestion G12H maybe if you can't find a JBL ? Big Full sound IMO.

Here's what the back of my 69 PR looks like. Got her for $150 about 15 years.

[cdw2000]

Great find! This amp has a lot of potential.

As far as the work around the power tube bias resistor: Someone may have changed it to re-bias for the 6L6 tube that you say it had. It looks like the cathode bias resistor is currently 1K ohm which would make for a very cold bias for the 6V6. You should change that back to the original 470 ohm. Also, I believe the 2K 5W resistor should be 1K based on the schematic. The 2K resistor drops the 6V6 plate voltage, reducing the amp's head room. If you want to restore the original voltage, you can conveniently re-use the 1K 5W resistor that you removed from the bias circuit.

You won't hurt anything by leaving at is, its just that the current configuration is not optimized for the 6V6

That extra capacitor is on the schematic. You should be using this schematic as a reference, based on the age people have put your amp at:

http://tdsl.duncanamps.com/link.php?...mode=schematic

Like others said that cap was added to help resolve some high frequency noise issues, probably due to poor wire routing on these later CBS produced units. Chances are you can remove it without a problem.

A lot of people like to "black face" these amps which basically means to convert them with some resistor and capacitor value changes to older black face version:

http://tdsl.duncanamps.com/link.php?...mode=schematic

Once again, a great find at a good price!

[NeoFauve]

Am I seeing a little burnt spot on the lowermost, horizontal white wire?

That's as technical a description as I can muster.

Nice little amps. Both the PR and the Champ.

[Totally bored]

Interesting stuff cdw2000


I'm wondering what my Bias should read if I hook up my Bias Rite.
I'm quessing from this http://www.webervst.com/tubes1/calcbias.htm

Class A amp around 400ish volts should be somewhere around 27-31 ?

[Totally bored]

Am I seeing a little burnt spot on the lowermost, horizontal white wire?

That's as technical a description as I can muster.

Nice little amps. Both the PR and the Champ.

Probably fried that little guy *sigh * and thats why they went to the 5 watt resistor maybe ?

[68Bassman]

Good find, wish I still had mine. They're great little amps.

Have some fun!!!

BW

[cdw2000]

Am I seeing a little burnt spot on the lowermost, horizontal white wire?

I think that might just be due to poor soldering skills. Hard to say.

[cdw2000]

Interesting stuff cdw2000


I'm wondering what my Bias should read if I hook up my Bias Rite.
I'm quessing from this http://www.webervst.com/tubes1/calcbias.htm

Class A amp around 400ish volts should be somewhere around 27-31 ?

That's correct. Being a single-ended Class A design it should be biased at about 90% of max. plate dissipation.

[Totally bored]

Thanks again.

I'm gonna investigate everything you said this weekend . I quess I will Hook up my Bias rite and see what it reads first and then go from there.

Peace

[phantomman]

Love my PR. I made a baffle for mine cheap. Baltic Birch Plywood from Home Depot. Cut out 12" hole then painted in flat black and stuck some grill clothe over it. Still have the original with the 10" mounted on it for quick easy change outs.

Consider a Celestion G12H maybe if you can't find a JBL ? Big Full sound IMO.

Here's what the back of my 69 PR looks like. Got her for $150 about 15 years.

Super lookin' PR, TB.

I wish a new baffle were that simple for mine. But it's an MDF cab wif a glue-in baffle (grille attached via velcro). A new spec-built pine enclosure will resonate better and be lighter to tote......my cab guy quoted me a hunnert an' sixty-five bucks, complete wif Tolex, grille clothe, hardware, the whole enchilada.

(just add salsa an' stir)

[Totally bored]

Super lookin' PR, TB.

I wish a new baffle were that simple for mine. But it's an MDF cab wif a glue-in baffle (grille attached via velcro). A new spec-built pine enclosure will resonate better and be lighter to tote......my cab guy quoted me a hunnert an' sixty-five bucks, complete wif Tolex, grille clothe, hardware, the whole enchilada.

(just add salsa an' stir)

FWIW my 72 DR has the MDF and the permanent baffle got warped. I was forced to either buy a new cabinet or fix the original. Fixing the original was worth a shot and cheaper so I ripped out the permanent baffle. Filled it all in with a wood puddy and then attached some wood that I screwed and glued to the sides to look like the originals and made a baffle like the I did for the PR. Came out very nice.


72 Deluxe Reverb ( Blackfaced electronically, cosmetically and cabinetally )
Paid $75 for her in 1992ish. The Internet wasn't big and nobody wanted them crappy old Fender amps. Blackface or Silverface.


And yea I'm a anal Libra. I made my baffles so that the speakers are mounted in a way that the writing on the speakers are horizontal. Can't deal with upsidedown or sideways mounted stuff.... WIERD !!!

[Cygnus X1]

Very cool, TB!
I paid 75 bux, but it was a drip edged 68.
Back in 1982 that is.

[phantomman]

I pushed my Princeton with some effects this afternoon an' that "paltry" twelve watts nearly shook my wife's Hummels outta their display case! Even wif that steenking Oxfart I can feel the mojo, seething to be released from within. A good twelve in a pine cab is gonna let this thang breathe.

As an aside, I've discoved that -- officially -- this amp does not exist. According the Fender Amp Field Guide, the non-'verb Princeton was discontinued in '79. Yet its serial number an' tranny codes indicate it was built in 1980. Prolly make for a good plot line in an upcoming episode of "One Step Beyond"......

[Totally bored]

Update if anyone is curious.

So I changed the 2k resistor to 1k and replaced the 1k resistor to 470 ohms or "back to stock" . I the measured the 6v6 tube with my Bias rite and got 388 plate and 52mv . The 52mv was way to high I thought so I swapped out the 470 ohm with a 1k . New measurements are 405 plate volts and 28mv. Much better I thought.

So I then decided to change the 470 ohm stock value on my 66 Vibro champ as that 6v6 tube was reading about 54mv and went down to 32mv with the 1 k resistor.

Heres a new pic of my 66 Vibro Champ and 74 Champ hanging out together.



So I have been A/B - ing both amps, cabs, and they sound very similar but I find Interesting how DRASTICALLY differant the speakers sound. The 66 Vibro Champ has a Weber sig 8 in her and 74 Champ has a Jensen P8R.

The Weber breaks up quicker and will compress more and is the perefect volume for a bedroom. Not very loud and you can play in front of it Dimed if you like.

The Jensen stays cleaner , is brighter and is ALOT louder than the Weber. Diming the Jensen will make your ears ring a bit. The Amp with the Jensen may even be loud enough to keep up with a Drummer and bass player ?


66 VC on the left with the Weber and 74 Champ on the right with the Jensen.




Peace.

[Cygnus X1]

I like the Weber sig's.
Good bang for the buck IMO.

Looks very nice, TB!

[68Bassman]

Very nice pair TB, the little Blackface Vibro Champ really has me wanting one of those, of course the champ is great too, but that BFVC..damn...

BW