Fender Silverface Champ questions

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Nick Sevilla
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Post by Nick Sevilla » Mon Jan 03, 2011 6:05 pm

mattcastore wrote:
unchartedthickets wrote:little tube amp sound with a little raunch at 10.
yeah i guess part of this is just me complaining about the never-ending quest for the "right" kind of raunch.

for clean stuff this amp suits me just fine, but that comprises about 1% of all the guitar playing i do, so i'm easy to please in that department.
So,

Are there any examples already recorded, of your kind of raunch? That might open the post to some arguing and discussion about how that raunch came to be, and perhaps even find out what could have been used.

Cheers
Howling at the neighbors. Hoping they have more mic cables.

???????
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Post by ??????? » Mon Jan 03, 2011 6:21 pm

True that.

Matt C.
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Post by Matt C. » Mon Jan 03, 2011 7:34 pm

??????? wrote:Does it have the original speaker? Does it have nice, original-ish old-stock tubes, or new "former communist bloc" type of tubes
the guy i bought it from said the speaker was original, but the markings on it aren't clear enough for me to know for sure. not sure about the tubes either, the rectifier and preamp tubes do say Fender on them, the markings on the power tube are barely legible but looks like Sovtek.

i'll try to find a recording with a guitar tone that's similar to what i'm thinking of.

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Post by ??????? » Mon Jan 03, 2011 9:10 pm

single NOS 6V6s aren't cost-prohibitive in the least. I wonder how you'd feel about it if you took that Sovtek out and put an actual nice tube in there.

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Post by Matt C. » Tue Jan 04, 2011 4:42 am

maybe a new power tube is worth a shot. should i be looking specifically to get a NOS Fender tube? or what other NOS brands might do well?

and in terms of recordings with the kind of guitar sound i'm looking for - if anyone is familiar with the Marked Men albums "Fix My Brain" and "Ghosts", that's kind of what i have in mind.

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Post by winky dinglehoffer » Tue Jan 04, 2011 7:49 am

This is worth noting again:
??????? wrote: The notable exception is the stock speaker, which can REALLY misbehave. Punishing this speaker doesn't always sound too good.
I have a silverface vibrochamp that I've had forever. Never was that happy with the speaker. I got a replacement a while back that I do like better, but another option is to use an external speaker cabinet. This can change your sound quite a bit.

It's certainly worth checking it out with an external speaker so you can determine if it's the speaker or the amp itself (or possibly both) that you don't really like.

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Post by ??????? » Tue Jan 04, 2011 7:56 am

mattcastore wrote:maybe a new power tube is worth a shot. should i be looking specifically to get a NOS Fender tube? or what other NOS brands might do well?

and in terms of recordings with the kind of guitar sound i'm looking for - if anyone is familiar with the Marked Men albums "Fix My Brain" and "Ghosts", that's kind of what i have in mind.
There's no such thing as a "Fender" tube. Fender never made tubes. Over the years, they did apply their label to tubes of other manufacturers, right up until the present day. They do own Groove Tubes now, but Groove Tubes never made tubes, either. They re-label imported tubes.

I would look for a 6V6 tube by RCA first. RCA tubes were some of what Fender used in the 1950s and 1960s. They're very good tubes. Ones with the black plate structure are more sought after. Gray plates are from the 70s and are also fine.

Other good 6V6 are by Marconi, Bendix, Mazda, Westinghouse, Tung Sol.

Totally acceptable and less expensive are by Sylvania, Philips, GE.

If you wanted to go new production, the JJ 6V6 is less shitty than the other modern 6V6s, and less shitty than all other JJ tubes which, in my opinion, are pretty shitty-- message board hype notwithstanding.

If you really want to try and make your Champ work, try a different 6V6 and a different speaker. I like Weber "Vintage Series" speakers a lot, though they're not super-cheap and you have to make sure one will fit in a Champ. The "signature series" are OK but not great in the 8" sizes.

Too much more tweaking than that, and you start to make it into a different amp. Of course it goes without saying that you should start any experiments with an amp that's definitely in good repair.

???????
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Post by ??????? » Tue Jan 04, 2011 8:25 am

Just remembered another very important potential cause of distortion in a tube amp, which might be very important in this case--

"blocking distortion."

This is what happens when the grid voltage of the output tube nears 0, or actaully goes positive in rare cases. Tube starts acting like a diode, and I could go on and on, but... the takeaway is that blocking distortion is a very "farty" kind of distortion that nobody except Neil Young seems to like.

It can happen in Champs. Changing the bias point by changing the bias resistor and bypass cap can help, and changing the grid stopper resistor to something 3.9k (up from 1.5k) can help.

Just a thought, anyway, for completeness' sake.

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Post by Matt C. » Tue Jan 04, 2011 8:58 am

so the output tube on this amp is supposed to be a 6V6GT. is it important to get a "GT" tube for it, or is that inconsequential?

i'll see if i can try hooking up an external speaker. my amp doesn't have a jack for an external speaker, which i thought champs were supposed to have, but i can figure something out...

again, thanks for all the information

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Post by Matt C. » Tue Jan 04, 2011 9:07 am

??????? wrote:"blocking distortion."
how hard is it to test whether this is actually what's going on?

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Post by ??????? » Tue Jan 04, 2011 9:10 am

Tube suffixes are confusing now, because modern manufacturers/rebranders do not always follow the old conventions/rules about it.

When your amp was made, "6V6" with no suffix was a metal-bodied tube, instead of a glass one. It's electronically identical to the glass 6V6 types, except it has an extra connection which is designed to ground the metal case. I think this is "pin 1." If your amp uses pin 1 on the socket for a 'tie point' for other components, avoid the metal 6V6.

6V6G stands for "glass." This is usually the big coke-bottle shape. They look cool. Provided they will fit in your amp (usually not a problem) they're exactly the same as the 6V6GT.

6V6GT is a glass 6V6 with the 'tubular' shape. This is what we normally think of. No difference internally from the 6V6G.

6V6GTA is a 'selected' or 'premium' 6V6GT

6V6GTY is a brown-base tube (base made of micanol, which is supposed to be superior for some reason). GTY tubes are military-issue tubes, and were made to be extra rugged mechanically.

Modern tube rebranders often add suffixes like "C" "R" and "STR" to the tube name to indicate, among other things, country of manufacturer. This makes the whole thing confusing. I don't know why the hell they thought they should do that. Thanks, Aspen Pittman.

To sum up-- with old tubes, look for 6V6G, 6V6GT, 6V6GTA, or 6V6GTY. All should perform identically in your amp.

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Post by ??????? » Tue Jan 04, 2011 9:12 am

mattcastore wrote:
??????? wrote:"blocking distortion."
how hard is it to test whether this is actually what's going on?
You kinda have to go on 'feel,' based on what you're doing when it happens and what it sounds like. I wish there was a better answer I could give you, but there's not. It's an 'experience' thing that you get when you've tweaked/tuned tons of guitar amps for best sound.

If you're experiencing a farty, jagged distortion sound, then I'd say it's worth at least considering blocking distortion as the cause. That and a flappy speaker.

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Post by Jim Williams » Tue Jan 04, 2011 9:46 am

When I bought my 1972 Vibro Champ, it also sounded like crap. The distortion was tizzy, the top end screechy and it hummed.

It came with the revered replacement "Jensen" speaker. That I hated, too tinny. I still have it if anyone wants it.

So I made it into something I like. First, out with the vibrato. I did a 2 stage preamp with treble, mid and bass controls. I added a master volume.
The speaker is an Eminence and sounds real smooth. I replaced the 1k 2 watt resistor in the power stage with a choke. That removed the hum.

Next, add some butt. I use a 6CA7 power tube, it's running at around 10~12 watts. I also removed the crappy can filter caps and replaced them with a pair of dual 100 uf 500 volters.

This amp screams. It drives a 4x12 loud enough for live gigs. Best harp amp ever too. Never pearcing, always fat and smooth. Does clean better too with the extra wattage.
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Post by unchartedthickets » Tue Jan 04, 2011 4:29 pm

Jim Williams wrote: So I made it into something I like. First, out with the vibrato. I did a 2 stage preamp with treble, mid and bass controls. I added a master volume.
The speaker is an Eminence and sounds real smooth. I replaced the 1k 2 watt resistor in the power stage with a choke. That removed the hum.

Next, add some butt. I use a 6CA7 power tube, it's running at around 10~12 watts. I also removed the crappy can filter caps and replaced them with a pair of dual 100 uf 500 volters.

This amp screams. It drives a 4x12 loud enough for live gigs. Best harp amp ever too. Never pearcing, always fat and smooth. Does clean better too with the extra wattage.
Kick ass!
:lol:

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Post by j_howell » Tue Jan 04, 2011 8:44 pm

You might also- and this may seem rather obvious- make sure the speaker is the correct impedance. I've seen the issue come up with Champs more than once, where the speaker was replaced with something that might have been decent enough, but wasn't the right impedance, reducing the whole shebang to a reeking pile of dook...
I like pie.

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