God Help Me-BF/SF Help Pleeze!!!!

I just found an early vintage Silver face Vibrolux with it's tube chart inside the cab reading "GZ34" for it's rectifier versus the normal 5U4 that SF's went to.

The amp sounded amazing - to make along story short, I bought it.
Just great condition, great reverb and tremolo or vibrato as it sez on the footswitch. Better cab material in this vintage than what I bought, I just had to have it. Either I got a very early SF amp to blackface specs, or this amp was blackfaced. Because I thought Fender changed to 5U4 in the SF years - no? Regardless, I now own 2 great amps.

I just figured it all out.....you guys won't believe this and I don't know yet if it's a good or bad thing but what I just bought is a Vibrolux Reverb "for Export Only" Amp which is actually an AA864 circuit that is wired for both European at 220 and American 120. That explain why it's got an extra powercord tucked away that I found underneath the reverb tank.

In America this is blackface amp. But this amp is clearly an AA864 Vibrolux Reverb "For Export Only" and has been retrofitted with a 120V cord, while still maintaining it's 220 cord (2 prong). WOW - I don't really care what it is it sounds so friggin awesome I can't wait to get some sample for you all.

This amp is an oddity and very cool. Now I just have to date it. I should have that done in about 1/2 an hour I hope. Just found the date code it was made in 1969 SCORE!!!!!!!!!!!!!!!! This is a blackface circuit in a SF amp and very rare all serial numbers match etc.

Weird, but cool! :cool: I'd keep using the GZ34 unless the plate voltages are unreasonable.

- Scott

Scott - they aren't because I have a blackface amp. Wow

Here's the Pix:

http://i5.photobucket.com/albums/y183/jogman/NewSFVR014.jpg
http://i5.photobucket.com/albums/y183/jogman/NewSFVR018.jpg

I should say - I have a SF amp for export only that is charted as AA864 with a GZ34 Rect tube and an AB763 blackface circuit. I'm almost having a heart attack.

The black mark line is where someone took a magic marker and blacked out "for Export Only" but you can read it right through the magic marker ink.

Here's the best I can do for now to show chart:

http://i5.photobucket.com/albums/y183/jogman/GZ34AA864013-1.jpg

Chabby, not trying to piss on your BBQ here, but just because it says 'AB763' or has a GZ34, doesn't mean it is a BF circuit. CBS continued Leo's pennypinching ways, and a great many amps kept getting that label weren't the prized circuit.

You have to get the circuit checked to see if it has the varied components. I had a 70 watt Pro Reverb that had a 100 watt Twin Reverb tube chart. The few SF that were AB763, were probably drip-edge grille '68s - which yours isn't. If you have any plastic wiring in the chassis it almost certainly isn't.

Like their guitars, the only consistent thing about FEI/FMI prior to FMIC in 1982 is their inconsistency.

You need to date the amp by EIA codes on the chassis and transformers, and speakers if original. The latest date is around when it can be considered to have been made. I'd be surprised if it comes in at ealier than around '72-73.

I doubt yours was made before 1970 because Export transformers with multivolt selectors for most models only arrived after teh BF era - some may have been earlier. We got them here in Oz (240 volt mains), and the earliest I have ever seen is a '72 Twin. Prior to that Fender Australia bolted a stepdown transformer in the base like the late 60's Concert I saw.

As we noted, not having the BF circuit might be a slight lefdown, but big deal. The amp is still solid, and if it's a pine cab more desirable than the later MDF units, lighter and probably tougher. That amp looks cherry, and the practical difference in value or souond of an early Silverface VR with AB763 and without is 4/5ths of F-all.

I dig those vibroluxes.

Just thought of another check of how early it is: Silverfaces before 1970 got 4 black line bars painted between the two sets of channel controls, overprinting the blue surround around the normal channel and the rev/vib channel. Yours doesn't look to have that. Pretty sure that means 1970's.

This amp so far falls outside some of the generalities of dating but I have dated the amp by it's serial number and am checking Transformers and chassis next. Used this to date by serial number:Which verified the very earli 69 date. I will get back with the rest of the story as it unfolds. Note that the black vertical lines were gone by 1968, this is a 69. Then they throw this at me - sheesh!:"Some, but not all, export models don't fit exactly into the sequence given and are usually from a year or two later than the serial number would otherwise indicate".
http://www.superchamp.dk/papers/dating_fender_tube_amps.htm

Well - I've been up all night researching this amp and it's definitley an odd duck. I filled out the survey with serial numbers transformer numbers, speaker numbers cosmetics and the works. It's a missing link of somekind.

Can't wait to lift the tranny and clean it up. Yes, I will bleed off the caps and take pictures. I will be keeping this jewel for number uno. Guess I have a 1979 VR thats going to be for sale soon that hasn't even been delivered to me yet - oh well. Can't afford to right now or it would be the start of a cool collection. Too bad, because I have a feeling the 79 even though its MDF will be cleaner cosmetically since it's 7-10 years newer. Can't wait to get clips of this thing on here for you all to hear. Punchy and clean and what a reverb and trem!

Chabby - congratulations on the new sweetheart my friend!!!

I have a DR from the same year, and it also notes the GZ34 recto tube on the chart. Yes, Fender would continue to use it's older tube charts on amps, even though some of them had switched to the 5U4 recto! INSANE! My DR has the GZ34, but certainly do NOT overlook the special tone qualities that a 5U4 has to offer. It's all a matter of personal tastes, but I think that we arrived at the conclusion that the 5U4 has a little extra compression (squishy), which is something you may, or may not like. I sure do like it in my 73 Pro Reverb.

Have 'er re-capped, and never let 'er go!

P.S. my DR is also missing the black lines on the control plate. It was sold to me as a 68, and Tim Swartz seems quite certain that it's a 69. In the end, it doesn't matter. The only thing that does matter is IT'S MINE! :twisted:

That amp still has the removable baffle on the cabinet which I think puts it at no later than right around 1970, but that may vary a bit depending on the model of amp.

Ditto on Fender re-using the tube charts. Actually, I don't think there ever was an AA864 circuit. I think that maybe Fender was rushing to get the tube charts out for this amp and jumped the gun a bit. The only printed version of a schematic I have ever found is the AA964. I have an October 1964 VR and it has the AA864 tube chart but from what I remember it matches the AA964 schematic.

You'll have to look at the bias circuit on your amp...it's probably the AB568 version. Also, see if it has the blue tubular caps or the blob type. Either way, congrats on the amp. FWIW, I have Reverend speakers in mine and most new ceramics have sounded better to me than the original Oxfords once the amp gets past 3 or so.

I played a VR at a Guitar Center and it had a nice tremelo sound. Cost about $1500.00 tho' so it was outta my range.

If I found one cheap then I'd get one but it's really too big for my needs anyway.

Dacious is right. You can NEVER date an old Fender by it's tube charts. If Leo was a penny pincher, CBS was much worse.

Serial number searches are not helping, perhaps due to the export PT...

Have you cracked the chassis and looked inside? Sometimes a builder's name is written inside an SF chassis, sometimes a date too (though my memory on if dates are is fuzzy).

I think you've got most of it down - it's a '69 at earliest, since it's export it may be a year or two later ('70 or '71).

It is very cool to have a strange amp - even better that is sounds good! Congrats on the cool amp!!!

Yep, Dacious in on the ball. I have a '77 SFDR using a 5AR4/GZ34 rectifier tube but has a wood cabinet not MDF. Definitely not stock, maybe a new cab, a mutt for sure but it sounds great and that's what matters most.

No doubt that is what matters most. And these VR's, I'm just discovering are every bit (and more IMO) as great as DR's. What really grabbed me with them is the punchyness of the 2x10s and the quality of the reverb. This thing could surf for days. But so sensitive to pick attack and pluck it makes you want to chickin pick just to hear that compressed, punchy tone with or wothout the reverb. Personally I like just a touch of reverb if it's quality I have found 3 on the dial to be about the most I'd usually need. The trem is just plain killer and fun to play with. It's an inspiring amp to say the least and dang if I won't have another in a week or two.

This one ain't goin nowhere though - ever. Well, I shouldnt say "ever" life can have it's ups and downs I'm finding out with the double whammy of a divorce last fall and unemployment last april. Thank God I had some savings and lot's of music equipment to sell or I'd be screwed. Any of you that don't have 6 months of salary saved up, get on it fast. Also, if it wasn't for my guitar, amps and music I'd be toast.

My SFVR is a 69 also, it has the blacked out for export tube chart and uses a GZ34 rectifier. It was internally not a BF. I had it blackfaced. And I agree with you that I prefer it's sound to DR's. My serial # is A1329X which maybe around September 1969. It had a lot of the so called brown turd caps.

Chabby, quick way to check if it's BF or SF schemo (or if someone converted it) if you have the chassis out: On the back of the power tube sockets should be 1500ohm resistors running across from pin 1-5 straight across the middle (pin 5 is oriented to the front of the chassis) - don't confuse these with the larger 470ohm resistors from pin 4-6. Running from pin 5-ground on the SF are the grid snubbers, small value ceramic disc cap. They are soldered to pin 5 at one end and to the chassis pointing towards the board on the other end.

If you have these, it's the later schematic.

Thanks Dacious I will and let you know. Non Vintage: Sounds like we may have similar beasts. My serial number is even earlier though at A1292X.
This amp was advertised as 70's amp. But the newest transformer on it is 236968 which is the output transformer which was made on the 68th week of 1969.

Thanks Dacious I will and let you know. Non Vintage: Sounds like we may have similar beasts. My serial number is even earlier though at A1292X.
This amp was advertised as 70's amp. But the newest transformer on it is 236968 which is the output transformer which was made on the 68th week of 1969.

The 68th week of the year?

I think I need to go to bed.:mrgreen:

Probably the only Fender amp ever made in the 68th week of any year. :razz:

Don't wish to hijack your thread but your amp has me wondering. I just rebuilt a Fender Princeton Reverb, I found a AA1164 layout online and started with that, but I couldn't read some of it and found another AA1164 layout, the only difference I can see besides being clearer to read being one AA1164 K-FD layout uses a GZ34 and the other uses the 5U4GB. I don't see any voltage differences, is it possible ones a European layout? I didn't know there was a difference so went with the 5U4GB, seems to work.

I'm laughing at myself guys...hey it was late at night and I was mentally drained. 236968 would be: the first 3 are just the part designation I just misinterpreted the decade and year stuff.

Darcy -No the 5U4 and GZ34 configs have different capacitors and wiring and the 5U4 has more sag, however you may be right. Maybe there was a European layout that used 5U4 scheme with aGZ34. One thing for sure, I'm finding anything is possible with older Fender amps as they seem to find new info all the time. With the Princeton I have no idea, but maybe with that circuit there is no difference and the recto's were considered interchangeable.

Another weird thing about this VR is that it's got a standard modern 3 prong power cord, then a white female terminal extention cord with a 3 outlet head.
Not sure what this is yet. It was either originally wired that way, or it was an attempt to keep it's original 220V cord intact, while adapting it to American Voltage.

Dacious - as I now have the chassis out I have confirmed that it has resistors running from pin 1-5. Plus, there is a red felt tipped date on the inside of the chassis reading "41/69". It also has the small value capacitors from pin 5 to the chassis. Also has the larger resistors from pin 4-6.
Also not sure if the 1 of that number 41/69 is a one or just where they might have had a false start at making the slash before the year. But if I had to bet it is a one, not a slash. Anything else to look for? It doesn't have the blue colored caps anywhere, but it does have quite few Mallory's and orange drops. And yessiree it's also got a few chocoalte drops as well. The caps appeared to be in surprisingly great shape for a 40 year old amp. Ir appears that someone with pretty good knowledge may have blackfaced the amp. I will post some pix ASAP of the very strange power wiring for you to look at. I han't quite yet determined it's purpose. But it was either rather ingenius, or really lame. Not sure which yet. But as I said, It's got the normal 3 prong updated power cord, then it was also fitted with another power cord which is a 3 outlet extension cord (2 prong inlets) hard wired to the power grid. It split upon entry into the chassis with one 1/2 going to powertube #1 and the other half going to powertube #2. I'm also trying to figure out if the GZ34 recto tube is just stuck into a 5U4 schemed slot, or if it was altered to be only for a GZ34. I studied the schematics but couldnt figure out the differences to look for. The wire inside the chassis is primarily plastic coated with the speaker plug and powergrid the only components that are cloth wired. The speaker plug from chassis to chassis is heavy duty and cloth covered, but from speaker to speaker it's the scrawniest plastic coated (brittle now) wite I've ever seen. That will be replaced as soon as I get some new Jensens in it (next week). I don't want to blow the original speakers.

Here's a good picture of how the white 2 prong stuff is forked out to the two 6L6's. This isn't factory either I don't think because I can see that a hiole has been drilled in the bottom of the chassis for this wire to come through. Then the normal 3 prong cord coming into the back of the chassis is cut before entry so the ground could be routed to the outlet on the back of the amp. Then they fused the cord back together with standard sleeved clamp style electrical connectors - kind of sloppy if you aske me. I will understand many differences when my 79 SFVR arrives on Friday for comparisons.

http://i5.photobucket.com/albums/y183/jogman/SFVR004.jpg
this picture is where the date is written in red felt tip, hopefully you can also see that the bias pot is wired blackface style:
http://i5.photobucket.com/albums/y183/jogman/SFVR002.jpg

Dacious - if you look hard at picture #1 you can see that the smaller resistor on powertubes are indeed connected from pin 1-5 back to front. Its a bit hard to see because the larger resistor running perpendicular to those is on top and kind of hides it.

So now that we know this amp has some blackface charachteristics, how do I determine if they are mods or factory alterations? Also whats the clearest cut way to figure out if the GZ34 is just plugged into what is supposed to be a 5U4 tube station, or is actually the proper one for my amp.

I don't have a pic in front of me, but i can assure you that the power cable wiring is not standard for the export model, leading me to suspect this is an amp re-imported to America from O/S and rewired by cutting off the cord.

On mine all the cabling is quite neat through the original inlet.

You also have a bias balance adjust, not a bias level. That and the presence of the suppressor caps indicates it is not a Blackface circuit. The silver Mallory bias cap which I think is too late also indicate that. Are those brown caps Spragues? Looks like infamous 'brown' caps but I've seen shots of BF amps with them too. Apart from the power cable, nothing looks like it's been touched. The general wiring BTW is neater than mine.

5U4 and GZ34 socket pinouts are the same: only way apart from part number to pick a difference is with a voltmeter to determine which power transformer you have. If your B+ is reading a bit over spec, like 450-470 volts I would presume it's the later transformer intended for the 5U4 (part # 12526A) and is reading higher than the schematic due to the more efficient GZ34. If it's 440-450 it's the correct one meant for GZ34s. Note this can vary due to how much current the tubes pull and other factors.

End of the day, it isn't worth obsessing over the poly caps or if it's BF or SF IMO - the proof of the pudding is the eating and if it sounds good, it is good.

Thanks for the post chabby.
Its a great read, and those pictures mark the first time I have ever seen the inside of Vibrolux!

Dacious - I'm not saying this amp is an original BF circuit, or AB763. I'm just saying it's got BF charachteristics such as the way the bias pot's been modified (wired). If you can see from the pix its definitely wired to BF specs.
SF specs from the pot would have a wire running off the back of the Balance pot to that large Mallory capacitor on the far left of the chassis (pictured in photo #1). Also SF would have a wire running from the balance pot tab nearest you up toward the first capacitor on the main board. Whereas mine goes back toward the Mallory I described. Also nitcie I have a wire coming off the balance pot's middle tab toward the two resistors coming off the first cap on the main board (whereas SF specs run off the tab nearest you to the first cap with a resisitor in between (also take note of the two added resistors just infron of the balance pot in my photo. I could cite even more improvments to this amp as well, but it would take a few pages. Suffice it to say that it's been either modded at some point as I've spotted at least 5 new mallory's, or they are in awful good shape and it came this way from the factory. My guess is someone fairly knowledgeble at least partially blackfaced this amp. I really need to determine whether it's setup for the GZ34 properly though as that could have negative implications if it is not set up to run the GZ34.

FWIW, my 69 has a GZ34. If your amp has a GZ34, sounds good and has a BF bias adj. it's probably the right rectifier. I think mine runs at 430V on the plates. I have a dual bias probe and PV probe. But it's been awhile since I last checked.

Actually there is something I just noticed too - those big 10 wattish sandbath resistors down near the tube sockets. I don't remember mine having anything like that. It's awhile since I looked in it. Not sure what that's about.

I think you're right, on second glance the bias pot doesn't look standard wiring. I've wired mine with an extra pot so it has balance and bias, and the wiring of the caps around the silicon diode is different to yours, too. There is at least one cap on your main board has been changed.

It might just pay to get someone to check it out. If your tubes aren't redplating and it sounds ok and everything works it probably is OK, but the power cabling is definitely a bit quaint.

As for if it is some BF/SF hybrid? Who knows. There isn't much really much diff to start with. Definitely an oddball for one reason or another, but then that would be true for a significant number of Fender amps in that era. Mine puts 445v on the plates with a 5U4.

Yeah - I bought both Weber's book and the tube amp book. They are both incredible resources with schematics of both BF and SF stuff, how to mod and just about anything and everything you'd ever want to know. Best 100 bucks I ever spent.

It has already paid for itself as the tech I used to go to charged me 80 bucks an hour. Not saying he wasn't worth it at all, just that I can't afford that, plus I love dabbling in electronics and have since I was a child. I'm learning so much so fast it's hard to digest it all, but I love it. I can't really read the schematics as well as I'd like but I'm getting there. For example, I have the drawings that should allow me to discern the differences between the GZ34 and 5U4 set ups, but can't see them for my ineptitude in reading the schemo's. Plus, they are never exactly like the drawing either. I wish. Sure would be some dressed out boards if they were. I can tell you that mine looks definitley like some kind of hybrid. Like some mad scientist genius went to work on it and knew so much he could do stuff like add two small resisitors to equal one larger one and vice versa. If you're really good you can do all sorts of stuff - even make em sound like marshalls. They even have a way to turn your normal channel into a marshall channel in these books - cool. Ways to make em sparkle and growl and all points in between. The cool thing is all this crap is reversible too. The tinkering one can do is endless.

There is so little difference between BF and SF, I wouldn't worry about it. If it sounds great, just play the hell out of it. I think Fender didn't start using MDF cabinets until the early 70's.

DO NOT go straitening out the wires, there ugly because lead dress isn't about appearance, it about rules. IF the amp sound great DON'T FIX IT.

I understand your enthusiam, but just play the hell out of the great sounding amp.

You received the amp with a GZ34, play it with a GZ34, if you have any doubts, check the power tube bias, that will tell more than whether or not what circuit it has.

It looks like it is ready for a cap job (electrolytics only!) and power cord
upgrade (check the electrolytics under the doghouse too). Plus, it looks as if someone might have converted it to cathode bias.


Like I say, "if it sounds good,, don't fix it", just do the maintenance (electrolytics and power cord)

....Also whats the clearest cut way to figure out if the GZ34 is just plugged into what is supposed to be a 5U4 tube station, or is actually the proper one for my amp.


Check the bias.

I will say this for a fact, it certainly doesn't run too hot in any way. Seems to be very well adjusted from first inspection, but I need to get some actual readings and let y'all know later. I'm not intending to anything but make sure everything is working topnotch on this amp. I will change the speakers so as to preserve them and make sure caps are all in working order - but that's about it other than general maintenance. Probably fix the powercord at some point. But the amp sounds great as it is. I will look at the filter caps tonight too.

There's another possibility to explain your amp Chabby. I hesitate to suggest it because it's unprovable, even more so than the purple Shoemaker Telecaster of Ol' Fuzzy.

When Silverfaces came out in 1968 at first they were BF amps with a new faceplate. Then FMI (CBS) seriously screwed with them. Twin Reverbs at least came out with a mixed cathode-bias/grid bias system. Slack, a regular post who hasn't been around in a while turned up a '68 drip-edge Twin Reverb which still had this a while back. He had other Twins and thought this sounded interestingly different.

Early feedback wasn't positive, and unsold ones after a month or so were allegedly returned to the factory and rewired. This was apparently all over by 1969. It's known that it happened to some Bassman 50 watt amps - I'd never heard about it happening to the two-tube reverb 6L6 amps.

Given yours has this texta 1/69 plus it's an export voltage unit, I am wondering whether maybe your amp was a demonstration amp or tradeshow special for maybe European Fender importers, and it scored an early SF proto chassis that happened to have the export trannies installed, plus the cathode resistors, and this was overlooked or maybe overlapped the early changes to the CBS circuit?

Vibrolux Reverbs were never the most numerous amp, for the same reasons they're so popular now - they are smaller and not as loud as the bigger 4 x 10 and 2 x 12 format combos and stacks so there might have been a gap between intro of other SF versions and this.

There would have been a delay between release of new amps and guitars in the US and Europe - in Europe due to recovery and post WWII import barriers Fender stuff was very expensive and slow-moving.

If this were a tradeshow amp it might explain the power cable being seriously non-standard, as all those european countries not only have different voltage, but different plugs, too. They might have rigged this arrangement so they could change it quickly.

You'd need to get it looked at by someone who knows to see if that stuff is all original.

Great stuff Dacious - I intend to do that too. It's just that the amp guy here is kind of a jerk. I won't name names but he has a real pet peeve over discussing anything, or doing anything off the pay clock if ya get my drift.
If he even knows, I doubt he would tell me in lieu of just telling me that I need to leave him my amp and he will let me know what needs to be done.

I called him the other day when I had the chassis out and he was an A-hole on the phone almost scorning me for having the chassis out - like I sinned or something. Screw him, I need to find someone else, somewhere else as I've never been spoken to like that by a person that might want my business.
That's one of the reasons I bought the books, so I don't have to deal with people like that. Let me know if you have any ideas of folks I could maybe talk to about the amp. I'm sure there are ways I could determine those things myself, if I just could be told what to look for, or asked the proper questions etc. Hopefully, when my 1979 SFVR arrives tomorrow, I will be able to do a little cross comparing that could tell me alot. I know the 79 has had a recent cap job, so I will be able to see something right there. I will report.

Well, the 79 SFVR arrived this AM and I've already been playing on it - it sounds fantastic and I think better than the 69. Very sparkley and that wonderful Fender thang happening. Getting addicted to that vibrato.

Once you have this configuration I can see why it's hard to go back. I will never forget the first deluxe I ever plugged into, it was like I'd met Mr. Tone and I never did fully recover from it. I did stray from it for a while, but there just ain't anything else like that Fender Sparkle. It's not that other amps don't have great clean tones available also, it's just that Fender's is so organic sounding -so analog, warm, finger sensitive and substantive.

Well, it's gonna be fun this weekend comparing chassis to chassis 79-69.
I'm sure this 79 sounds so good because of the cap job. I was a bit alarmed when I first plugged it in it didn't make any sounds. I turned it off and realized the Rectifier tube had jiggled loos in shipment. One other thing that could be a problem with the amp is that the tube sockets are a little loose. Not to the amp, but to the tubes. Not a real positive tightness when you push them in. Probably going to have to check that they are in tight everytime I crank her up. SO that might be the first thing I should fix.

Bought the 79 off ebay for what I think was a real fair deal. And now seeing the condition of the amp and hearing it's tone, I'm very pleased.

Just for a nice thing to look at here is a dream rig for me and any other time in my life I would keep both these and AB forever. The verdict is out, the 69 is better sounding but I have to say, it's very close. The BF differences are there however and put the 69 just a tad infront of the 79.

It's kind of hard to explain the differences but its most easily heard in the bass. Though not as extreme, it's like the difference between a DRRI and a Tweed deluxe. A bit tighter bass and slightly more touch sensitive. But the 79 is fantastic too and no slouch. Alas, it's gonna have to go on the block though. 79's cab is in better shape and better shape over-all, I'd say it's in betweeen good and excellent for a 79. The Cab on my 69's a bit rougher, but oh well. I have to play tonight so I won't get at the chassis today, but I will tomorrow. Talking about ecstasy - see below! A/B Switching dream

http://i5.photobucket.com/albums/y183/jogman/dreamrig009.jpg

This is for those of you who have enjoyed and/or benefited by this thread - check out the guts of a basic, but well service 1979 SFVR. Great to compare with my 69 guts/chassis I posted pix of. You can now see some differences between my blackface SFVR and a normal SFVR with 5U4 set-up here it tis:
http://i5.photobucket.com/albums/y183/jogman/SFVRGUTS2.jpg
http://i5.photobucket.com/albums/y183/jogman/SFVRGUTS1.jpg
Obviously, this one has been re-dressed with heavier wire and is neatly dressed compared to your standard issue. Also has had a cap job, but sounds completelyt different from my 69. It sounds very good and very Fendery, but way different. Can't decide if it's better or not, but the bass is way more defined as is everything really, bigger, bolder maybe louder. But I like the blackface tone better. There's that sag thang with the regular SFVR that is quite different.