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FDP Forum / Fender Amps: Vintage (before 1985) / a few questions regarding the Vibroverb

Next 20 Messages  
Roy Earl
Contributing Member

west coast USA

Feb 26th, 2008 09:29 PM   Edit   Profile   Print Topic   Search Topic

I am looking to correct the issues on my second 63 brown vibroverb (2x10). One thing I noticed tonight was that one of the reasons I didn't think it sounded as good as my first when I got it is that apparently there is a reverb failure of some kind. reverb knob all the way around does not effect sound at all. no reverb it seems. the RCAs are in on the back panel.
my question on this aspect, which is my most serious concern given I have near 8 large in this amp... is this a problem that has many potential causes? also can the average amp tech fix this kind of problem CORRECTLY or is it something that requires me sending the amp to a specialist? I know not how the reverb tank works on one of these so I apologize if the question is silly.

Ok, that aside, it seems these 63 brownies had both electrolytic caps on the left and of course some good ol blue moldeds on the right side of the board. This amp has had the 3 Astron electrolytic caps 25/25/40, 25/50/75, and 250mf 6WVDC removed. theres some nasty orange globs there now. Now as its near impossible to find undamaged NOS Astron minimites laying about, whats the closest thing Im gonna find to replicate them in design. i assume the repos you see on ebay are just minimite covers over a contemporary cap. is there a vintage STABLE cap I can use? I am just too naive when it comes to these things.. I mean isn't a cap a cap? Since they were clearly moving over to Ajax Blue Moldeds, why not use them across the board? Was it a matter of leftover Minimites? or blue moldeds were not what wanted to use for some reason? any speculation??

Also, I have the original speakers but don't wish to use them in fear of damaging them. The ones the amp came with just suck.
Now I can't help but thinking back to that latest Vibroverb that was on ebay. The amp had a 50 output transformer rather than a 35 125A6A. it also had these 60-61 Oxfords you'd likely find in a Concert amp. Huge Alnicos in them. Now was that amp given the big magnet Concert speakers for a reason? Originality aside, theory being that those earlier Concert speakers with the big ole Alnicos in them were some fine speakers that could handle some punch. As far as vintage speakers go and the intention being utility use rather than originality (already have that angle covered) would it be a horrid choice to use a pair of those big Alnico Oxfords in one of these? I intend on buying a vintage pair and a pair of Webers and seeing which I prefer.

Anyway, theres a few things to chew on and offer an opinion if you would be so kind. many thanks!!

vmr
Contributing Member

USA

I think, therefore I jam
Feb 27th, 2008 05:57 AM   Edit   Profile   Print Topic   Search Topic

Roy,

I would replace all the electrolytics with Spragues and just be patient looking for old ones - if you really feel you need them. The reverb tank likely has a broken wire, so take it apart and inspect it. There are very tiny wires connecting to the 2 RCA sockets and it is fairly common for those to break from metal fatigue. If that is the problem, they can be carefully soldered and reattached. I'd try to save the old pan this way. As for the speakers, those brown magnet cover Oxfords would be a great idea in the Vibroverb. The original speakers were known to be way underpowered for the amp. I wouldt just get a set of Weber 10A125's, the equivalent of Jensen P10Q's? You will be very happy with the sound of those.

Also, a pic of the circuit board with the replaced caps to see would be helpful.

VMR

Negotiator
Contributing Member
********

USA

Feb 27th, 2008 08:53 AM   Edit   Profile   Print Topic   Search Topic

Post a picture of the front of that bad boy too.

We love pictures of old brown vibroverbs.

She sounds like a keeper, that's for sure.

SoK66
Contributing Member

USA

We had the hit but Van got the money
Feb 27th, 2008 09:23 AM   Edit   Profile   Print Topic   Search Topic

Ditto on the reverb, based upon your comments broken wire inside the tank the most likely issue. A bit of a microsurgery job to fix, but worth it to save the old tank.

Not quite sure if you're refering to Astron Minimite electrolytics or the yellow Astron caps on the board. I wouldn't trust a vintage electrolytic. The guy on eBay selling Minimite repros apparently just uses a new Atom or TAD cap and puts a repro cover & end caps on them to mimic the old vibe. Pretty expensive, but in the case of a classic like you have might be worth it. As for the Astron yellow caps on the board I've seen a few '63 amps that had them mixed in with blue moldeds, guess Leo must have been clearng out parts stock. My '63 Bandmaster has blues in the Normal channel & PI, Astrons for Vibrato channel tone & coupling caps.

IIRC the '63 VV had the brown plastic magnet covered silver frame Oxfords like the '61 & '62 2x10 brown Super. Speaking from experience the original Jensen P10s in pre-'61 Supers had a life expectancy measured in minutes at gig volumes. Not everyone's cup of tea, but the Oxfords were a lot more durable speakers. There's a set on eBay right now that the guy's been trying to sell for several months. Overpriced, of course. Pretty sure you'd like the Webers VMR suggested, too.

vmr
Contributing Member

USA

I think, therefore I jam
Feb 27th, 2008 10:01 AM   Edit   Profile   Print Topic   Search Topic

Follow up:

"This amp has had the 3 Astron electrolytic caps 25/25/40, 25/50/75, and 250mf 6WVDC removed"

The above is confusing. The only electrolytics on the main board should all be 25mf/25VDC. The originals were dual capacitors with 25mf/25mf/25VDC (possibly 50VDC, makes no difference). I don't see a 250mf on the schematic anywhere. Under the Dog House, all electrolytics should be 16mf. A picture would help us help you sort it out.

VMR

Roy Earl
Contributing Member

west coast USA

Feb 27th, 2008 10:45 AM   Edit   Profile   Print Topic   Search Topic

The 250 was the bigger cap next to the pilot light. sorry about the confusion. the others that were removed and sent with the amp were the orange electrolytic minimites. but they may not have sent a third as there are three spots on the board where replacements were put in. plus it looks like something funky was added to the power tube socket area. Photos to follow.

there are no yellow Astrons on this, nor were any sent. I have a couple yellow 022/400 I had laying about I was considering using on a 63 princeton, but thats another story altogether. took the verb tank out and all looks kosher. no missing or severed wires. when you turn up the reverb on the amp you only get a slight buzz if your right in front of the speakers. the switch when actuated will cause the buzz to go on and off so I will assume the switch is good.

I will load pics. thanks

Roy Earl
Contributing Member

west coast USA

Feb 27th, 2008 11:08 AM   Edit   Profile   Print Topic   Search Topic

here the site where the pics are loaded. the tank pics are a bit blurred but no apparent wire disconnection issues.

there are three spots on the board that appear to have 6 caps replaced. I wish to replace them with vintage stock, but am hesitant to replace with the minimite electrolytics. Now can I use some stock of blue moldeds I have in those places? problem being is Im not sure I have what would be usable values. I suppose I should just take the unit to my tech with the bag of blue moldeds and see if he can replace any of those new ones with them. Now I am assuming in these spots of the board that the original electrolytics were not used for some special tonal reasons?? again the question begs, why were those spots which now hold those new caps have orange minimites in them before when it seemed they were swinging into the blue molded era? simply had those leftover but didn't want to grace the amp completely with 50s minimite caps when they were fishing for a different sound?

Obviously blue moldeds would likely improve over whats there now. Also does the bigger cap over by the pilot light have any influence at all on the sound produced? I would assume not, but I am often wrong when I assume...

the reverb tank looks on the surface to be a rather simple concept, but for the life of me can't say why it doesn't work. guess the tech will have to test the connections.

63 vibroverb

vmr
Contributing Member

USA

I think, therefore I jam
Feb 27th, 2008 12:05 PM   Edit   Profile   Print Topic   Search Topic

Roy,

All the electrolytics on the main board look fine to me. I see no place where any tone caps (e.g. blue molded) are missing. What you see is a basic replacement of all the 6 electrolytics (originally 3 dual caps). Not sure what is going on around the power tubes, looks like some diodes were added by a tech along the way for "safety". I doubt if they are needed. I would have them removed, but they are probably not changing the fundamental amp performance. Given the value of your amp, I suggest you replace all the electrolytics with fresh Sprague Atoms throughout. Six 25/25mf on the main board, and all the caps in the dog house, and the cap in the bias supply section next to the pilot light (100 mf/100v seems to be the popular size here). I also don't care for those big white ceramic resistors on the power tubes. i would use 2 or 3 watt 470 ohm metal oxides.

As for the reverb tank. Do you have another one in a different amp you could try, just to competely rule out the tank? Does it crash when you shake it (with the amp on)? if not, it's the recovery amp stage. try a new tube in the position 4, counting tubes from the right going left, looking at the back of the amp. If it doesn't crash, try a new "driver" tube in position 3, counting from the right. If none of that helps, it could be the reverb transformer. You will need a tech unless you want to try and replace it yourself. But even all that may not solve it if there is a bad resistor or cap in the circuit somehere. This is all basic stuff for a tech. Just don't let him throw away any replaced parts.

VMR

(This message was last edited by vmr at 02:52 PM, Feb 27th, 2008)

SoK66
Contributing Member

USA

We had the hit but Van got the money
Feb 27th, 2008 02:50 PM   Edit   Profile   Print Topic   Search Topic

Nice amp!!!! Ditto on VMR's comments.

(This message was last edited by SoK66 at 02:51 PM, Feb 27th, 2008)

John Peden

U S A

John Peden
Feb 27th, 2008 02:54 PM   Edit   Profile   Print Topic   Search Topic

Roy, I to play a 63 Vibroverb and I think it is the BEST club amp there has ever been. I'm kind of a fanatic for keeping amps original but the amp that goes out has to work and be reliable. I live in N Y C and the work on mine was performed by Blackie Pagano of Tubesville who is now in L A. He knows these amps and does great work if you need it. I changed the gold Oxfords in mine to preserve them and they were getting tired. I may be the only person who will recommend the Jensen Neos but in the Vibroverb they sound so full and rich IMHO. A tip on speaker replacement , courtesy Todd Sharp in Nashville Put 2 16 ohm speakers in the Vibroverb. The OT wants to see 8 ohms and 2 16s wired parallel is the way to go. John Peden

vmr
Contributing Member

USA

I think, therefore I jam
Feb 27th, 2008 02:58 PM   Edit   Profile   Print Topic   Search Topic

I forgot to add,

Anybody - especially a tech - who would put silicone blobs to hold down wiring on an amp of this caliber should be taken out and hung by their thumbs and made to listen to modeling amps all day ; )

Also, what is going on with those blue resistors on one of the power tubes? It looks like they may be two 100 ohm (typically) resistors to ground off the heater wires. That is normally done over at the pilot light to reduce hum. Your tranny has a center tap, so you shouldn't even need those. Ditch 'em, along with those diodes in the clear shrink tubing. ; )

VMR

(This message was last edited by vmr at 03:08 PM, Feb 27th, 2008)

Naked Clarke
Contributing Member
******

NJ, USA

Southbound
Feb 27th, 2008 03:05 PM   Edit   Profile   Print Topic   Search Topic

(This message was last edited by Naked Clarke at 04:42 PM, Feb 27th, 2008)

vmr
Contributing Member

USA

I think, therefore I jam
Feb 27th, 2008 03:30 PM   Edit   Profile   Print Topic   Search Topic

Hi John,

Welcome to the FDP! I think I met you at a Long Island Guitar Show at Nacho's Blackguard Book booth.

If you are the same person, you simply MUST share your story about that extraordinary one-off tweed-twin-in-a-Super-tweed-cabinet amp story. Wasn't that amp custom made for Jimmy Bryant? And, uh, since you happen to be an extraordinary still photographer, how about some pictures of it?! Please start a new thread about that amp.

Again, welcome.

John Peden

U S A

John Peden
Feb 27th, 2008 03:48 PM   Edit   Profile   Print Topic   Search Topic

That's me. Check out the new Tom Wheeler book "The Soul of Tone" 60 years of Fender amps. 2X10s RULE!!!!!!

DoctorAmpVonCamp
Contributing Member
***

USA

Feb 27th, 2008 04:28 PM   Edit   Profile   Print Topic   Search Topic

Roy,
You amp just needs a little love.

And John, lets see some great pics of that killer amp.

The new 10" Celestion Gold/40 watt ALNiCo watt speakers will ship out in late may early june. They have the same 1 3/4" voice coil as the 12" Golds.

The 10" Golds will be incredible in the Vibrolux Reverb/Super, Bassman tweed, Princeton reverb, and all the others.

Can't wait.

SoK66
Contributing Member

USA

We had the hit but Van got the money
Feb 27th, 2008 05:38 PM   Edit   Profile   Print Topic   Search Topic

Ditto x2 on VMRs comments above, that amp didn't need any mods.

John, thought I recognized the name. Welcome aboard! Absolutely love your recent work in the Wheeler amp book. I'm consuming a bit every day. Anyone who hasn't gotten it yet, it's a real treat.

Doc, I just ordered a Marsh 5F4 kit w/o speakers in anticipation of the Celestion Golds being available soon.

Roy Earl
Contributing Member

west coast USA

Feb 27th, 2008 06:09 PM   Edit   Profile   Print Topic   Search Topic

So spague atoms are your choice for where the three dual electrolytic caps were yanked? I know there were no other factory installed blue moldeds on it. Do any of these three spots greatly effect the sound? Something is sure effecting the sound on this thing and it's not just the nasty speakers the guy stuck in there. I know ebay sellers have to talk positive, but those of you who saw the auction probably also thought the guy was a little over the top (ebay item # 130194032340).

I intend on having my tech rip out whatever is attached to those power tube sockets.

So anyway, spargue atoms on the board? anyone else care to input their choice of caps that if they had the amp and even if they had to pay $50 a cap to replace what was in there, what would it be?

Also, any thoughts to what to put in the filter slots? Consensus seems to be that even if I have a bunch of NOS Mallorys (not pulls) and even if they test good, I still shouldn't use them?

I want to keep it as original as possible of course, and since I have another 63 Vibroverb with a replaced OT I don't see this one getting heavy use as my other one is more cosmetically broken in and sounds better than this one (at least for now). The one I bought some months ago simply sounds haunted. never heard anything like it before. Given the tonal nature of that one I am disinclined to yank out the replaced OT which appears to be late 60s vintage. Some combination. not sure what, but I don't want to mess it up.

I am a realist..to a point. I want it playable and safe, but do Not wish to deviate far from the components that the factory put there, and at the very least wish to replicate them tonally as best as possible, over cosmetically (i.e. overpriced ebay minimite repros).

SoK66
Contributing Member

USA

We had the hit but Van got the money
Feb 27th, 2008 06:38 PM   Edit   Profile   Print Topic   Search Topic

I think we may be confusing you. The caps that were replaced were the old brown 25/25uf 25v electrolytics, the blue moldeds don't go in those spots. I wouldn't use any old stock electrolytic, particularly in a sweet amp like that one. Not worth the risk. As VMR suggested, replace all those electrolytics with Sprague Atoms or F&Ts, including the filter caps in the doghouse. Stick with stock values, can't go wrong.

Oh, one other thought wrt your reverb issue. Have you tried switching the two cables around? Sometimes they get plugged in backwards.

(This message was last edited by SoK66 at 09:11 PM, Feb 27th, 2008)

John Peden

U S A

John Peden
Feb 27th, 2008 06:48 PM   Edit   Profile   Print Topic   Search Topic

Roy, I work on my on amps up to a point then I call in the techs. Something must be truly wrong with your amp. I've owned 3 of them and they were all pretty much the same....GREAT!!! Why don't you start a process of elimination . If you have 2 put them back to back and try plugging in the reverb pan from #2, then if that doesn't cure it try the speaker jack from #2 then the tubes one at a time. If it still sounds bad then you have to assume it's in the circuit. I know this is obvious but I've had real good luck with the replacement transformers from Mercury so except for the expense I don't think you have to worry about replacing an output transformer. For what it's worth my ranking of "Where did the tone go?" problems #1 the values in the circuit must be on,#2 the speaker, #3 the output tubes,then the rest of the tubes (in my amps the rectifier and phase inverter tubes have a noticeable effect.) Of course, as everything else gets cleaned up that remaining problem becomes MORE BOTHERSOME. Don't give up. They're great amps. Richard Smith calls it Leo's best. J.P.

Roy Earl
Contributing Member

west coast USA

Feb 27th, 2008 08:40 PM   Edit   Profile   Print Topic   Search Topic

I presume that the Sprague atoms being electrolytic is why you recommend them? the originals being electrolytic and these are the best you can get in electrolytic type? I assume you do not want to use caps that are not electrolytic in nature in order to preserve the nature of the beast? Obviously you can get some really nice $20 caps, but they aren't electrolytic. So is the theory that the $20 a pop caps would not be appropriate in this specific application?

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FDP Forum / Fender Amps: Vintage (before 1985) / a few questions regarding the Vibroverb




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