Difference between a BF and SF Vibro Champ?

[cody420]

I think I'm gonna snag a vibro champ off of ebay for practice and recording. I've noticed the SF are going for a good bit less than the BF. I know there shouldn't be that much difference between them, but for someone who has heard both could you please try to give a comparison. I play jazz, blues, a little country with a tele with lollar cc, and a heritage H-550. Not looking for much breakup. Thanks.

 

[-CB-]

Not a hill of beans difference, with the exception of maybe the speaker, depending on the year. Internally, and the transformers...absolutely identical.

 

[bongo]

I did a 6 hour session recently using a 70's SF Vibro Champ and was blown away by the sound. If a BF sounds better who cares. This was a fabulous, cranked sound driven by my 335. go for the SF

 

[Mik]

Might be a different value of a resistor in the BF and SF VC amps, I've heard that's it and has no discernable effect on tone.

I was playing a nice clean SFVC last night accompanied by a nice clean SFC, great small amp clean with some break up when desired.

If you're looking for clean, you might consider a SF Princeton, not Princeton Reverb, but a SF Princeton. Too clean for me!

Mik

 

[TDPRI]

When Fender/CBS started to "improve" the amp line, they started with the bigger more expensive amps and generally worked their way down the line. Along the way, little inexpensive amps like the Champ and VibroChamp never got any changes because by the time they worked through the bigger amps the managers and engineers had learned that the changes were not all that well received. Plus, many of CBS' change mongers had already started to wash out or move on.

Also, the reason the bigger amps needed the SF "improvements" was because Fender had pushed throughout the 60's to make bigger and louder amps. In the process they brought in some problems in the engineering that made manufacture of amps without parasitic oscillations more troublesome. Since the little Champ, etc, never got a power boost it didn't need re-engineering.

This is just my interpretation from reading the various Fender history books. If it's not accurate, I'm sure others here will correct me.

Go Silverface and save.
Paul Green

 

[a42]

Not a hill of beans difference, with the exception of maybe the speaker, depending on the year. Internally, and the transformers...absolutely identical.

Aren't the BF and SF cabs made from different material?

 

[BrianF]

I believe that is true. I believe the SF cabinets are made from heavy and dense particle board, and the front baffles are glued in place. Also the lead dress (how sloppy/neat the hand-wiring is) and some electronic component brands probably were different. The basic circuit is the same though.

 

[Marky D.]

I've owned 4 champs..

BF Champ (Weber Sig Alnico 8), Vibrochamp (Stock Jensen), SF Champ (Stock), 59 Tweed (Weber Sig Ceramic). The tweed has the nicest spongy sound at medium volumes. Of the other 3, the SF(non vib) had the most gain and tonal flexibility. Used to blow harp through it - what a sound! Shouldn't have sold it - dang! The BF Vibrochamp was traded for an Alesis Microverb - what was I thinking? At least I still have the Tweed and BF Champ..

Condition of the caps, speakers used, etc. may have an effect on my analysis.. Suggestion: don't be afraid of the plain old SF Champ if you don't use the vibrato ..

Good luck!

 

[PhatTele]

There are differences between the BF and SF Champ/VibroChamp components. One of the key ones is actually the power transformer.

If you look at them closely, the SF Champs have slightly larger power transformers. They are the same ones that are used in Princetons and Princeton Reverbs. These PTs run a bit hotter than the BF versions. In the cathode biased Champ, this translates to a little more "oomph" (I don't know how else to describe it). Because of this, I actually prefer the sound of a SF Champ over a BF Champ. The SFs can be louder and have cleaner distortion when turned way up.

Other differences include the quality of components and construction (SF = messy). Here, the BF Champs are the clear winner...but not enough to justify the price difference, especially when the SFs can be tweaked to sound even better than the BF versions.

BTW - If you're not looking for much breakup, I'd go ahead and buy a SF non-reverb Princeton. You can get those for $300 - $350 without any trouble.

 

[-CB-]

There are differences between the BF and SF Champ/VibroChamp components. One of the key ones is actually the power transformer.

The transformers had slightly different sizes of bell ends, but the hole layout and electrical properties were always the same - its a 70ma transformer 330-0-330.
The BF Champ transformer was used on BF Princetons (both models), and the SF Champ transformer was used on SF Princetons (both models) and they are completly identical electrically.

The only cabinet that MIGHT have been fibre is the Bronco. The SF and BF champs always MDO baffles, and some sort of low grade pine cabinetry. The baffle was screwed in on BF amps and early SF amps. After about 68, all Fender baffles were inset into a groove in the cabinet itself and were non-interchangable (or only with great amounts of effort).

Internally, both always used carbon comb resistors, capacitor du jour. The OT's were identical. Speakers varied from brand to brand and some have better tone than others - the biggest differences are in speaker imho.

 

[jjmantele]

AA764 Vibro Champ:

20-20-20 Filter Cap(s)
1wt cathode resistor on 6v6
125P1B Power Tranny
Lower voltages written on scheme
2 prong power cord on scheme

AB764 Vibro Champ:

40-20-20 Filter Cap(s)
2wt cathode resistor on 6v6
125P1B "or" Dual Voltage 010020 Power Tranny
Higher voltages written on scheme
3 prong power cord on scheme

I suspect only the earliest BFs have the AA764 setup but the 3 prongers generally came out around 72 on Fenders I think, so there may have been some phase-ins?

The Dual Voltage tranny does not automatically mean there is a switch for dual voltage. Just that there are 4 primary wires. Series connected for 234volts and parallel for 117volts as in my '74 little monster.

 

[a42]

The only cabinet that MIGHT have been fibre is the Bronco. The SF and BF champs always MDO baffles, and some sort of low grade pine cabinetry.

Well, I'm not sure about that. I've got a '76 Champ and the Tolex is peeling in a couple of places. There's not that much exposed, but it doesn't look or feel like pine.

 

[-CB-]

It doesnt feel like pine! It feels like shipping pallet wood, made from old skids! Its pine tho.

As for the voltage - forget em. I have first hand info on that, and its literally take a first year engineering student and a drawing and a Simpson VTVM and let em have at it!

I doubt they put very many AA764's into production before the AB764 was adopted the same month! From that point forward to the end, all the same. The option of the dual or triple voltage xformer was always there, but you really seldom see em in the USA.

 

[peteb]

"The transformers had slightly different sizes of bell ends, but the hole layout and electrical properties were always the same - its a 70ma transformer 330-0-330."

dang, CB, you know a lot about these

I had never heard that

I seen they look different, and I have heard of higher voltages and higher head room but never any technical specifications


that isintersting

howd you find that out?

 

[JohnnyCrash]

-CB-'s right. Nearly every time. I live (and was born) 2 seconds from the old Fender factory here in Fullerton, something tells me you coulda worked here.

Something also tells me you're not human -CB-... call it a woman's intuition, wait whaT?! Damnit I've been drinking again.

Seriously though, the REAL differences between BF and SF are nil, yet the argument always goes on - "they're night and day" - yeah, right.

Let a few come across the bench and crack em open... "cap du jour" is occasionally right though... but that may be due to replacements over the years.

Trannies have always been the same. "A month" sounds about right, the different circuits were so close together the marketing phrase "mid-quarter slipstream" barely applies.

Get a BF or a SF, it's the same dang amp! Hell, put two SF's together and you'll hear a difference - such is the nature of amps with such a long shelf life... give or take 5% to 10% for each cap and/or resistor, plus everchanging speaker manufacturer changes, plus different aging conditions, plus repairs/mods over the years, ad nausea... and you've got no two amps sounding alike within the same year of manufacture!

Great amp either way (which is in fact, the same way)... get one and be happy

 

[JohnnyCrash]

Well, I'm not sure about that. I've got a '76 Champ and the Tolex is peeling in a couple of places. There's not that much exposed, but it doesn't look or feel like pine.

Pine is the cheapest (and one of the softest) woods for actual road use. Perhaps that's why the revolutionary "bolt on" Fender used it.

It's pine, but it aint the same grade you'd see in a Twin/Bassman. I've had to replace baffles on Champs and that was eye opening, to say the least.

 

[-CB-]

"The transformers had slightly different sizes of bell ends, but the hole layout and electrical properties were always the same - its a 70ma transformer 330-0-330."

dang, CB, you know a lot about these

I had never heard that

I seen they look different, and I have heard of higher voltages and higher head room but never any technical specifications


that isintersting

howd you find that out?

Well, I've bastardized enought Champs in my day

And the spec and model number of the transformers used in those amps are published.

I had a good customer (from my gunsmithing life) who was retired as a production manager at Fender, Fullerton. When I found that out we had lots of good chats (ie voltage issues on schemos). In fact that whole subject came up from my noticing the amazing rising voltage on one of the Bassman schematics. Has more voltage down the line than at the power supply.

 

[vic108]

Dang, and I thought it was those ghostly midnight visits from ol' Leo there CB?!

 

[endzone]

BTW - If you're not looking for much breakup, I'd go ahead and buy a SF non-reverb Princeton. You can get those for $300 - $350 without any trouble.

Please send me a source where I can get one at this price!!!

 

[PhatTele]

As far as sources go...I get mine off of eBay. Go out to "Completed"+"Princeton"+"Musical Instruments" You'll see some expensive ones out there, but you'll also see them going for $275-$395. Perhaps I've been lucky. I got three back last fall for under $350...all working perfectly fine. In fact, I just picked up a late 70s push/pull Princeton Reverb for $430. All it needed was a reverb tank. Meanwhile, people have been buying these and earlier SF models for well over $600. I also just picked up a '68 Bandmaster head for $275 (Buy It Now) that just needed a little cleaning...not a common experience but it was a good eBay experience.