Fender Vibrochamp

[mrdazobee]

I have seen one of these for sale locally and I have dated it to 1980 via the serial no.Is there any difference between this and the 70's model people rave about?This one has a voltage selector on the back I don't think the 70's one did?

[???????]

the champ and vibro-champ never changed, in terms of the circuit, since the blackface-to-tweed revision.

The component parts may be from different sources/suppliers, but the working design of the amp will be no different.

[mrdazobee]

Just read a review on the harmony central site.Some guy on there has 2 vibrochamps.One from 72 the other from 1980.He says they both sound different from one another. "The 1972 is thinner, clearer, with more bite and the 1980 is thicker, lower tone, with more umph! The 1980 is much louder than the 1972 also. The 1980 was made for Europe with a voltage switch and special plug and is much heavier"....mind you he did say his amp tech changed some wiring on the 80's to set it up like a blackface of the 60's?

[???????]

that sounds weird to me.

It is possible that your champ and his champ (could they be one and the same?) were both made for export. They would have had a different power transformer, but nothing else would be different.

UNLESS the amp in question was a "Champ II" or a "Super Champ," those are early 80s amps that are altogether different.

Here is a good site with info:

http://www.ampwares.com/ffg/champ_vibro_sf.html

[Mudcloth]

Some guy on there has 2 vibrochamps.One from 72 the other from 1980.He says they both sound different from one another.

It's possible the difference is in the speakers. It's also possible that the 12AX7's are very different sounding. I have a '66 Champ and and a '67 Vibrochamp and they don't sound alike at all, sans the vibrato. Even the cabinets make a difference in how they sound. The VC's cabinet is beat to shit and it has such a great vibe/sound. It just moves them molecules in an unusual way.

[mrdazobee]

He says the speakers are the same in both but in the 80's version he put a new 12ax7, and in the 72 version a new 6v6 tube.Would this have an impact on the sound and volume between the two?

[???????]

that might, or one might be broken.

Or any number of things.

Explain in detail the differences between the sound of the two and I can give you some possible places to look.

The Vibro Champ is a VERY simple amp. There are only a few dozen parts in one of those. Shouldn't be too hard to track down what is responsible for the difference.

[Mudcloth]

My Vibrochamp came back alive in a big way when I stuck a new [old] 6v6 in it. Huge difference. It's funny how it works. You get a great sounding tube amp and over the years it slowly, yet unnoticably loses it's oomph until one day you're like "Hey, this thing sounds like doo doo." New tubes, bias, and cap-job later it's back to it's old glory and you're like "What took me so long to notice?". Not that a Champ needs biasing which is another beauty about this amp.

[0xeneye]

The circuit is so simple, and there is very little difference between silver and blackface. More important is the bias, the input signal, the tubes, the speaker, and then the circuit differences, possibly in that order.

[Kindly Killer]

AFAIK there is only one VC circuit. I poked around for info when I built a clone, and I only found a couple versions of the same schematic and layout.

The biggest consideration I can think of is to evaluate old amps on an individual basis. Decide whether you like it how it is, with components that have drifted; plus what are you going to do when those 30 year old caps finally demand replacement. When an amp gets that old it really is one-of-a-kind.

A brand new VC is a good amp. Very Fender, takes any pedals, volume is manageable for recording, especially with the stock speaker. On mine I replaced the midrange resistor with a pot and built it as a head instead of a combo.

[mrdazobee]

So the difference between the two is down to the individuality of each amp not because of the year?Two amps made the same year could sound quite different from one another?

[Mudcloth]

So the difference between the two is down to the individuality of each amp not because of the year?Two amps made the same year could sound quite different from one another?

The may come out of the factory sounding vitrually the same, but given some time and other factors things begin to change. Tube amps are really dynamic that way. One amp may be played 10 hours a week on 10 and the other might be played 10 hours a month on 5. The speakers and tubes in both those amps would age accordingly. Caps and resistors have an ever changing life of their own as well.
We're also talking about taking a tiny little guitar signal, amplifying it a whole lot in the preamp stage, and then amplifying that signal a whole lot more and sending out to a speaker. Any tiny changes in resistor value or caps leakage get "amplified" along with it. Two amps made in the same year can sound totally different 20 years later, especially after changing out tubes, which have an incredibly dynamic life of their own.

[???????]

the parts in those amps are 20% tolerance.

That means a 100k resistor could be anywhere between 80k and 120k

Furthermore, it will be between 80k-89k or 111k-120k because anything closer than that would've been selected out by the supplier as a more premium 10% tolerance part.

So they've been 'individuals' from the beginning.

Not to mention that Fender changed suppliers often, and was known to use whatever was laying around. They would often substitute something if they were out of something, I've seen all sorts of weird things in Fender amps that are totally stock. They also used different brands of stuff. The caps might be Astron paper-in-oil, Mallory polypropylene, or the generic reddish-brown ones, or the later shiny dark blue ones, or anything else. If they ran out of something, they would often just send someone down to the local electronics shack to buy whatever they had until the next shipment came in.

Transformers during and after the blackface era were generally Schumacher but sometimes they bought them from Better Coil and Transformer. Speakers could be Jensen, Oxford, Utah, Rola, CTS, or JBL. Since the speaker and transformer and tubes (which could be anything by now) are the heart of the sound of the amp, well you know...

Add to that the fact that parts drift and change with age, repairs may have been done, one might not be 100% up to spec, etc and it's anybody's guess what a vintage Fender amp will sound like.

I tend to think of it like a basic 'recipe' made by your grandma. If she's making a batch of cookies, she doesn't measure everything out exactly. She throws in a little of this and a little of that, if she's out of something she will substitute something else, it's largely an approximate science. Each batch of cookies will come out a little different, but they will almost always be good and recognizable as "grandma's cookies," even if it's somewhat of a variation on a theme.