FENDER VIBROSONIC BROWN FACE

[tag101]

I played one of these today for the first time, and it sounded fantastic! (see pic below) having said that, I think something may be wrong with the amp. In the first channel, there was almsot no sparkle or high end at all, and in the second channel, there was almost no low end. This was regardless of where the volume was set, although the tone controls still worked. To get the first channel to be bright, you had to dial up the VOLUME of the second channel. this added all kinds of top end to the first channel, and to get the second channel to have enough body and low end, you had to dial up the firsts channels volume. So the key to getting great sounds, was balancing the two volume controls from each channel. Once I did that, the tone was off the hook great, but it was not an easy thing to do. I have owned bassmans and lots of vintage fenders where one channels volume SLIGHTLY effects the others volume or tone, but nothing like this at all. Is this "normal" for the Vibrosonic, or is something wrong? I really appreciate any help, as I am considering purchasing the amp. Thanks in advance! (Its a 1/15" speaker whch I have never liked, but in this thing its amazing!


Amp pic:
http://www.larkstreetmusic.com/list/pict/vibrasonic.jpg

[martin manning]

That would be a 5G13 Vibrasonic. Looking at the schematic I don't know how the volume controls could be interactive, as the normal channel volume control is before the stage feeding the mixer, and the vib channel volume is ahead of the stage feeding the vibrato. Perhaps that example has been modified in some way? Of course putting a patch cable across the inputs would make both volumes active.

[tag101]

That would be a 5G13 Vibrasonic. Looking at the schematic I don't know how the volume controls could be interactive, as the normal channel volume control is before the stage feeding the mixer, and the vib channel volume is ahead of the stage feeding the vibrato. Perhaps that example has been modified in some way? Of course putting a patch cable across the inputs would make both volumes active.

Thanks for your help!

They are going to take it apart and see on Thursday. Maybe they are jumpered internally? I am looking forward to seeing what is up.

Any input from someone who has played one of these would be a big help as well.

[Firestorm]

By all means have a look inside (and check for original transformers). They are sort of rare. If it's buggered at all, see if you can Presbyterian Buzzy down from $2500. I wouldn't mind owning one of those.

[rdjones]

The two (2nd) preamps share a cathode resistor and bypass cap at point "D".
Both preamps share a supply filter cap at point "A".
Failure of either of these caps could cause some interaction between the 2 channels.

I agree that under normal conditions the two channels should not have any interaction as described, and that the channels may be jumpered in some way.
Did the channels interact through all 4 input jacks ?

I dig the Brownface Fenders !

rd

[tag101]

The two (2nd) preamps share a cathode resistor and bypass cap at point "D".
Both preamps share a supply filter cap at point "A".
Failure of either of these caps could cause some interaction between the 2 channels.

I agree that under normal conditions the two channels should not have any interaction as described, and that the channels may be jumpered in some way.
Did the channels interact through all 4 input jacks ?

I dig the Brownface Fenders !

rd

I have a feeling this is the problem, because both channels sounded like $hit on their own. Maybe both will totally rock once its fixed, and if so, I may own the amp! One of the best Fender cleans I have every heard. The feel was total rubber! It was so easy to play, even I sounded pretty good!

[martin manning]

That's a good point rd. With the age of this thing those caps could very well be gone.

[Firestorm]

Nothing beyond restoration if the transformers and speaker are intact. Tag101, if you don't want it, tell Buzzy it sounds like crap, beyond redemption, etc. and I'll call him. I'd pay $1500 sight-unseen. Probably too close to what he paid, though.

[Teleguy61]

The first Fender amp I ever played was a brown face Vibrosonic with the
15" JBL. Loaned to me by a friend, who was the kid brother of the owner's friend. I was 14, and just learning to play guitar. Put me on Fender amps with JBLs for life.
Great amp! Good luck!
PS:the owner was some ticked when he came to get his amp and his friend didn't know where it was. He was a mite testy by the time he got to my front door. All ok in the end, but it was years before I could afford my own Fender.

[Reeltarded]

Might it not also be the board conducting a symphony of electrons?

I loves me some brown deluxe. I ain't no 15 fan, but good luck anyhow!

[Firestorm]

What happened with this Brownface? Just asking.

[tag101]

What happened with this Brownface? Just asking.

Not sure. I went in yesterday and it was doing the same thing, but not as severe. Odd. The amp sounds perfectly clear and there are no odd noises or anything. It seemd perfectly fine. Its one of the most clear amps I have ever heard. With that being said, there was VERY old Cowtipper 45 sitting next to it, and I am trying to land a newor used Cowtipper pro 2. Hopefully I will know by tomorrow..... There is also a used fender SRRI that sounds AMAZING I have my eye on. I played two nice vintage ones, and a brand new RI, but this used RI seems to have all the best qualitys of the vintage (Warmth) plus the brand new one (Tightness and focus in the bottom end). I think its the speakers being worn in exactly right.

[rp]

see if you can Presbyterian Buzzy down from $2500.

Buzzy's a Presbyterian?!

[Firestorm]

see if you can Presbyterian Buzzy down from $2500.

Buzzy's a Presbyterian?!

Well, no. But the traditional ethnic slur is offensive so I won't use it. Presbyterians, on the other hand, are chiefly Scots, notorious for their frugality, so it's an appropriate alternative to the Judaic one. And being as I am Presbyterian (and part Scots) I'm entitled to say it until it becomes politically incorrect.