1979 Fender Vibrolux Reverb with tremolo issues. Should I charge more for silver panel amps???

 Here was a mess.......

Fender 2x10" Vibrolux Reverb circa 1979. When it came across my bench it had your typical noise issues and one nasty "bumpity bump" from the tremolo circuit. 

Once I opened it up the first thing I noticed was someone had done a rather half assed job at a black panel conversion (AA964 circuit.) So I figured I may as well complete the job. I changed all the elecrolytic caps first which helped but there was still that tremolo issue. Curiously enough it  was far worse when you turn the reverb up! So I started by eliminating that boost circuit, which takes away a length of wire that is about 8" long traveling from the reverb transformer output to a switch on the back of the volume pot. That made a little bit of difference, less wire generally equals less issues. But that didn't knock out the problem. 

Sometimes this problem is as simple as changing the tremolo tube or the "bug" network (the photo cell neon bulb thing) or just putting a .1 cap across the bug from the 10M resistor to ground. This was already standard factory goodness by then and the amp had that, though they used a .01. I upped it to a .1.....

Next I noticed the 2.7k cathode resistor and the 820 ohm resistor were opposite of where they were on a black panel amp. The 2k7 resistor should be on the left closer to the tremolo tube and the 820 ohm resistor should be on the right closer to the reverb recovery / mixer tube. That made a sizable difference. And it came that way from the factory. I next changed the cathode cap on the 100k resistor on the tremolo tube to a 4.7uf. That helped too.....

But, I like things to be close to perfect. When you turn up the reverb it still did the bump like my parents did in 1978 at the disco in Germany. Cool for the dance floor though they were told to "get a room" by an English fellow.

So what to do next? 

The silver panel amps can be cantankerous. They're just not that well made. The foundation is there: great transformers, hand wired, this one retained the 5u4 tube rectifier, but they just used things like cheaper wire. I've had noisy silver amps that I literally needed to change the wire to get the noise level down.

In this case it became clear to me they just used too much wire! Lead dress is important. 

I mean, look at this jive:

An experienced tech can see the problem. The wires on the tremolo tube are way too long and crossing the wires on the reverb recovery tube! This is factory wiring folks from the CBS days. So I proceeded to shorten the wires and move them away from one another....

That knocked out the problem. I wound up shortening the leads throughout the amp. Overall, it lost about a foot + of wire!

I cannot imagine this isn't a problem that developed with time. The wiring was all factory and the amp has been played hard for the last 40 years. I'm stunned to see that no one attempted to correct this issue before, or maybe the previous owners never used the tremolo circuit. That's plausible. Tremolo isn't for everybody.

So now this amp is ready for proper use. It's got a great sound and I feel good about it going to a new home. When I had my own shop I'd roll my eyes whenever a 70's Fender came in. Most were okay, straightforward, but many were challengers. 

So hopefully this post will help another tech out. Do look at the lead dress. There was a good amount of haste in those days at Fender. I mean look at a 1979 Stratocaster. My first guitar was one and it was terrible. Seriously a sad, heavy, careless piece of corporate lack. This amp is better than that guitar, they were just five dollars away from making both well but chose to cut corners. Fortunately this amp is now terrific cause amps are easier to transform! My poor old guitar will never be good. I didn't feel bad giving that one away years ago!

JB

My personal 1969 Deluxe Reverb

This is my personal Deluxe Reverb. I just bought it from Division Street Guitars in Peekskill NY. Great shop, give them lots of business!

I added the blue jewel on the light bulb. Blue on silver is just right for me.

This post is just about general routine stuff. Amp had the rectifier tube removed and replace with a couple of 1N4007 diodes. Gross...... Well, at least not for me. 

Fortunately the power transformer is intact, easy fix. Clip thise sad diodes out and put the yellow wires back to pins 2 and 8:

Next was just the filter caps. Sad, old and leaking. I didn't keep the sleeves this time cause, well, who cares? It's a silver panel amp! You can see they are leaking badly. Please don't leave stuff like this intact for the sake of "collectibility." Remove and replace.

I like to put two 80uf@450v caps in series with two 220k 2 watt bleeder resistors in the first filtering stage. Keeps me from getting zapped! And if you have an amp that has 500+ volts sitting there before you hit standby, this is safer. 80+80 in series is 40uf....... Perfect for a tube rectifier where you do not want to go over 50uf.

Next is the 470 ohm grid resistors. One was replaced but I just did both. You can also see those .001 capacitors from pin 5 to ground. Gone. Never needed them! The AB763 circuit is just better.

So I'm not the biggest fan of those "Brick drop" capacitors. A bit harsh. I replaced them with a mix of Sozo blue capacitors (lovely!!!) and some old Ajax caps and Sprague Black Beauty caps. 

In the phase inverter I went with a .002 cap feeding it from the preamp. The silver panel amps use .01 which I don't like much and the black panel amps use .001. I like it somewhere in between. You can freely experiment with values there and see what you like. 

This is my first amp with reverb since 1992! New sounds for me. Absolutely beautiful voice. I used all American and European NOS glass. So hopefully the public will get to hear this some day when Covid has passed. And it shall pass like everything else. Let's keep it real and get through these times together. God I miss live music!

Of course, these old Fender amps have a way of getting away from me. So as long as I don't sell it.....

I should add, the late 60's Fender amps with the removable baffles like this one are some of my favorites. They're consistently great sounding. I'm not a fan of the tweaks they did but those are minor and it's a piece of cake to put them back to the black panel glory. The transformers are pretty much the same, this uses a 5AR4 rectifier rather than the 5U4. That's important. The amps made soon after this are very good still, right up until the 1980's. They're all hand wired. But these late 60's amps, you have more fun options. If I wanted to I'd replace the baffle with Baltic Birch. Mojotone makes those ready to install. I've done this for clients and for a couple amps I owned that had cracked baffles. The later ones the baffle is glued in. Bah! Why???!!! 

So do consider one of these if you have fancy champagne taste on, well, a good wine budget. No they ain't beer sadly, but still priced more reasonably than the vaunted black panel amps.....