Brian wrote:

Well they did put an extra tube in it.

Surfbeat, you post this question every couple of years. A silver face reverb unit is a pretty rare thing and I'm guessing not too many people have experience with them. Still, it's a fairly simple device and a good amp tech should be able to tell you what's wrong with it. Good luck!

Yep, been posting the same question for ten years, maybe longer, but noooo more thanks to thee geek techie I found.

eddiekatcher wrote:

According to Sprung and Teagle, the main differences between the original (and reissued) reverb units and the 76-78 silver faced ones are:

No choke in the power supply, relying on bigger filter caps to smooth out the DC.
Hum balance circuit for the tube heaters

S&T did not do their homework before they wrote their opinion.

The 76 reverb was targeted to a different player than the pre CBS, just like most of the CBS amps.

Vocals became primary, guitar leads took second place.

We play the surf genre, so, the tone we look for is different than those who playing the English invasion stuff.

Single diode in the power supply replaced the three in series from before

A 6V6 driver tube rather than the original 6K6

An additional 12AX7 at the output stage of the unit to act as a buffer.

The input jack and output jacks have a connecting wire to short the output when no guitar was plugged into the input.

Seems like Spanky Twangler had one of the SF units at one point. I did too in the 80's and it worked fine. Better than any pedal by a long shot.

ed

OzReverb wrote:

I nearly bidded on a '76 tank on FleaBay two days ago but decided against it after reading this thread and other posts on the lack of drip and the reason for this. Saved me $$$$

That was a wise move.

Stay away from the 75-78 SF reverb unit unless you have a good comprehension of electronics. If you do, and you can find a 75-78 for no more than $300, then, and only then but it.

By doing so, you can get the 75-78 to sound mo better than the 61, but pay a fraction of the cost.

If you don't know electronics, then get as re-issue for about $400. IMO, (and I have been playing since 61, so I know what surf music is suppsoed to sound like) they are about 98% right on to a 61.

98% of us won't know the difference.

eddiekatcher wrote:

According to Sprung and Teagle, the main differences between the original (and reissued) reverb units and the 76-78 silver faced ones are:

No choke in the power supply, relying on bigger filter caps to smooth out the DC.
Hum balance circuit for the tube heaters

Single diode in the power supply replaced the three in series from before

Very little difference here. Probably doesn't change tone at all but lowers the hum level.

A 6V6 driver tube rather than the original 6K6

Reasonably big change and the substitution of the 6V6 (much more common tube) is under biased in this circuit. So the breakup characteristics of the driver tube are different.

An additional 12AX7 at the output stage of the unit to act as a buffer.

This is probably a good thing in most cases. It corrects a deficiency in the original design. 6G15's are very touchy to the combination of mix level and the characteristics of the cable you use to plug the output into an amp. The 4th tube fixes that but really only changes tone if it would have otherwise been screwed up.

The input jack and output jacks have a connecting wire to short the output when no guitar was plugged into the input.

**No effect. Besides, who cares what happens if it's not plugged in.

** Now I do see a bunch of other subtile tonal changes in the cap values. Those will make big changes ... maybe good, maybe bad. But all in all I still believe that "drip" is a function of the spring tank. Here's where older 2 spring designs will out perform the modern 3 spring, smoothed over units. I think that's why the Surfy Bear unit is getting such a great reception.

I can't believe this is a $400 mod though. Looks like about $15 in parts plus a new driver tube to me.**

Last edited: Jul 03, 2015 10:05:42

SlacktoneDave wrote:

Screen door springs are ok for keeping the flies out.... but, get a real pan for happy life.
~d

Quite possibly the best sage-like advice on the entire internet!

Thanks Dave!

Actually that was my post, not Eddie's. You skipped over the part where I said the biggest changes would happen when you changed all the eq turnover points from the cap values.

SlacktoneDave wrote:

Warning ... Scotch Tape and thumb tacks will not help those later reverb units.... major revamp would be the only hope... and, yes, the spring unit is from where the magic emanates after the electronics are redone. Screen door springs are ok for keeping the flies out.... but, get a real pan for happy life.
~d

Very good advice Dave. If you come to Tony's welcome home party, you bring your Super and 64 RU, I will bring my 76 RU and Showman and you will see your advice was right on.

On a side note, I received a call from a promoter who is trying to put together a surf show at the Armory and wants First-Third Wave bands to perform.

Since my Majestics were First Wavers it looks like we are in. I passed on your PN to him, so if you receive a call, that is how he got your number.

I was up in Moreno Valley a few days ago and Sam was telling me you are keeping him as buy a I have been. We did some shows at the River and my Showman began acting up from the 120 degree heat. But it was fun.

But the silverface reverb unit is not a 6G15 so its not ever going to sound like one. It's a completely different circuit.

By the time the Silverface units came out, surf was a distant memory and the drip was an outdated sound. I imagine it was more of a pain than a pleasure - musicians must have been begging Fender to get rid of it. Which they did, by the sound of it. For CBS to make a circuit more expensive to make, they must have been pretty determined.

If I were you, I would sell this unit to someone who will enjoy it for what it is, because it's bringing no joy to your life at all. Sell it and buy a 6G15 which you will enjoy using. It seems a no brainer to me.

http://thewaterboarders.bandcamp.com/

Last edited: Jul 02, 2015 02:10:18

No, there's more than just a faceplate change. Look at the circuit, there is an extra buffer stage linking the tone and output stages.
http://acruhl.freeshell.org/mga/schematics/amps/70srev.jpg

Plus the reverb tank is driven a different way.

http://thewaterboarders.bandcamp.com/

Last edited: Jul 02, 2015 09:03:48

Holy moly: Based upon the comments on this Thread I sure opened a 55 gallon barrel of worms on this subject.

My intent was simply to find someone to give me practical advice that I could use to get my 76 RU to sound like my 61 6G15.

After spending about $500 over ten-twelve years to get the 76 RU to do what I wanted, sound like my 61, the task was finally accomplished.

In fact, the 76 now sounds way better than my 61.

As for caps effect on tone, caps do have a significant impact on tone; not the value, but the manufacturer. That said, like replacing the pan or tubes, neither of the three mentioned, or combining all three will change the tone to the point that the 75-78 will make anyone playing the surf genre appreciate it. As designed, CBS did not market the 75-78 for the surf genre.

The only reason I did not get rid of mine was based on the presumption that the extra tube, as well as change of the design, would give me a better sound. That thought was based upon pure hope which never materialized until modifications were made.

The bottom line is, if anyone reading this Thread is contemplating with the idea of buying a 75-78 Silver face reverb unit to use in a surf genre environment, then unless you can get it for $200 or less, and you have the skill to do some surgery on the unit, go purchase a re-issue for no more than $350. If you don't follow this advise, I guarantee you that you will be sorry. (Just read other Threads here on this subject and you will find, everyone stating that their 75-78 RU do no sound like a 6G15 or RI.

According to Guitar Players 2015 Price Guide, hand-wired 75-78's sell in the range of $500-$600 in excellent condition.

If you pay that much, then you will need about another $100 plus about 6-7 hours of work to make it work in the surf genre.

At that rate, you would be better off buying at 66 for about $750, maybe a tad less, or more.

I have talked to 6-7 musicians who own/owned the 75-78, listened to at least two units and the consensus was that everyone was dissatisfied with the tone.

If anyone out there has a 75-78 silver face reverb unit, and does not want to throw away the investment, but wants to make it work in the surf genre, then contact me.

I think I am now the resident expert on this unit.