New (tiny) amp day

Make it loud here.
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runrunrun
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Re: New (tiny) amp day

Post by runrunrun » Sun Jul 13, 2008 7:24 am

OK, this thread so makes me not wanna sell my Champ. :) Thanks guys.

What´s your favourite overdrive / booster to use in front of the little beast? I´m currently using a bad monkey which sounds pretty sweet, very usable as a booster aswell.

My Champ currently has the alnico Weber speaker aswell, though I seem to like the sound of the original speaker more for some reason.  ??? Feels like the sound is almost too refined with the Weber... maybe i like my amps a little farty  :P
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benecol
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Re: New (tiny) amp day

Post by benecol » Sun Jul 13, 2008 7:46 am

Image

Maggie, that's a beautiful amp - for me, the bullethole on the front makes it! If it was too pristine I'd be scared to use it.
runrunrun wrote: What´s your favourite overdrive / booster to use in front of the little beast? I´m currently using a bad monkey which sounds pretty sweet, very usable as a booster aswell.
I'd be interested to hear this too - I'd heard conflicting reports as to the pedal-friendliness of Champs, but so far mine loves my muff and Big Cheese, is pretty harsh sounding with my wah, and I really need to try my overdrives and booster in front of it. Still very much in love though - smuggling it into work tomorrow to take a look at its guts.

* crosses fingers that he doesn't find the innards of a Gorilla 10 watt inside *

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runrunrun
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Re: New (tiny) amp day

Post by runrunrun » Sun Jul 13, 2008 7:47 am

Here´s a picture of mine, taken after i bought it last year...
Image

what´s the deal with the different kind of on/off-switch in some champs... Mine is build in 1976, maybe they changed to these kind of switches in the seventies...
Last edited by runrunrun on Sun Jul 13, 2008 7:56 am, edited 1 time in total.
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benecol
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Re: New (tiny) amp day

Post by benecol » Sun Jul 13, 2008 7:52 am

Someone else with the same power switch as me! Thought it was some weird aftermarket bodge, but I've since seen Broncos with this switch. What year's yours?

Also, can any of you afficianados explain the difference between inputs one and two for me please?

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runrunrun
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Re: New (tiny) amp day

Post by runrunrun » Sun Jul 13, 2008 7:58 am

benecol wrote: Someone else with the same power switch as me! Thought it was some weird aftermarket bodge, but I've since seen Broncos with this switch. What year's yours?

Also, can any of you afficianados explain the difference between inputs one and two for me please?
Haha, sorry i just edited my post to add the comment about the switch... meanwhile you commented the same thing :) So, yeah, been hinking about it too
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chrisjedijane
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Re: New (tiny) amp day

Post by chrisjedijane » Sun Jul 13, 2008 2:05 pm

Mine's a '74, and has the same switch as runrunrun's
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Re: New (tiny) amp day

Post by øøøøøøø » Sun Jul 13, 2008 8:20 pm

benecol wrote: Someone else with the same power switch as me! Thought it was some weird aftermarket bodge, but I've since seen Broncos with this switch. What year's yours?

Also, can any of you afficianados explain the difference between inputs one and two for me please?
Fender, from Leo's era up through CBS production, was always known as using whatever they could get from their suppliers and/or whatever they could find around the shop.  They probably got a good deal on those switches, bought some, used them up, and then went back.  Or whatever.  You just never know with Fender.

As far as the inputs, that's a bit of an interesting thing that's not talked about too much.

Here's a snippet of the very beginning of the schematic:

Image

See that each input has a 68k resistor

Now it was assumed when the amps were designed that anytime something was plugged into input 2, there would be something else plugged into input 1.  It was never thought that someone would have any reason to plug into input 2 alone! 

So when there is something plugged into input 1 alone, the signal goes through both 68k resistors in parallel, for an actual 34k resistance to the grid of the first 12AX7. 

If instruments are plugged into both 1 and 2, the 68k resistors (in theory) isolate the instruments from one another (in practice not so much) and they are mixed together before the first stage. 

Now if an instrument is plugged into channel 2 only, it sees a 68k path to the grid but also a 68k path to ground.  This results in some of the signal being attenuated to ground, resulting in a darker sound that's slightly "padded down," or lower in volume.  So coincidentally, it just so happens to work well to pad down an instrument with a very hot input (i.e. a combo organ or keyboard of some sort) when you don't want it to clip the first tube.

So, short version: hole 1 is normal, hole 2 is padded down for lower input signal and a darker sound. 

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benecol
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Re: New (tiny) amp day

Post by benecol » Mon Jul 14, 2008 11:26 am

Very informative; thanks for that. Cracked open the Vibrochamp today:


Image

Looks pretty neat, eh? Now, I wanted your advice as I'm a little confused. Online, everyone is saying that the electrolytic capacitors inside these amps can go bad, and need changing every ten years or so (mine's from 1979,and looks all original inside). Weber will send them to me for about $80... Now, both Torres UK and Watford Valves here in the UK have said to me that if there's no hum or hiss on the amp, and no obvious discolouration or buckling of the cap cans, then I needn't change them; Torres went so far as to say that when they get silverface stuff in, unless there's anything wrong, they leave well alone.
I suppose what I'm worried about is primarily damage to the amp, and secondarily, impaired sound quality: however, the amp sounds lush (and will sound even better when my new speaker arrives), and I've been told (Watford and Torres again) that there's usually a fair bit of warning before a cap goes, and the worse that can happen is the fuse blows, or at worse, a valve.

So what do you think I should do? Spring for the cap kit, or stick with it as is?

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Re: New (tiny) amp day

Post by benecol » Mon Jul 14, 2008 3:26 pm

Thanks for that - it's been sat for at least three years pretty much unloved in a guitar shop, so I doubt it's been betting regular play; I've bought the caps, just to be safe.

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Re: New (tiny) amp day

Post by øøøøøøø » Mon Jul 14, 2008 3:40 pm

I don't think you'll regret that move.  :)

Just considering it like buying a vintage automobile and changing the oil as soon as you get it because you don't know when it was changed last. 

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benecol
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Re: New (tiny) amp day

Post by benecol » Mon Jul 14, 2008 3:48 pm

Good analogy - appreciate your help.

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