I'm not a tech, but, I know his repair and redesign was necessary to make that thing sound good. I think he just threw away the original circuit board, and put in a proper one. I know the guy who fixed it. I think the short version of this thread is just understand, and accept this as a warning to not get involved with one of these if you want to sound like The Original Safaris. Besides, the older ones look cooler, too.

You, on the other hand, may have a different opinion.

~dave

I changed out just the pot to one of 250k, does it get more 'verb? Yes. Does it get too much and overdrive? Yes.
What do you suggest boomer? I do not want to do any major mods, just dial in a bit more verb. I was thinking of maybe trying a 50k instead of the 250k and leaving the rest. Or I could leave the 250k dwell pot, and remove the 100k resistor coming off the dwell before the .0022 cap.

UPDATE

I removed that resistor and connecting the now missing link with wire. It did help, but I can only run until about 4/5 on until I overdrive. Likely I will have to use a lower value pot. 250k is just too much, even with the 100k resistor that follows it removed.

dboomer wrote:

mikey3 wrote:

I have a 76 also, I am quite curious as to what may happen if I just replace the pots. According to the schematic on the '76 the dwell pot is 10k, where on the 6g15 it is 250k.

There is a resistor that needs to be changed along with the pot value. The SF circuit limits how much you can turn up the dwell so in effect when you are are 10 on a SF be much lower on the 6g15.

Last edited: Jul 03, 2015 14:00:57

dboomer wrote:

So let's get together sometime and have a couple of beers and listen (or even better play) some surf tunes together.

Lets do it. My Showmen are down at the Elks lodge next month, on the 15th. Come on down and join us.

If you have the time, log onto Youtube and pull up 'The Showmen Live at Rhythm Collision II" so you will have an idea what we will be playing.

You and I are definitely beating heads together on a subject that I know a lot about, but am having a hard time explaining. I readily admit, I know very little about electronics. I can only experiment, and when I do, I often screw it up.

That said, when I looked in the mirror and asked, do you know what the hell you are doing and the answer was "hell no," I sought out experienced help.

That help was able to provide the answer to my elusive question, why won't this %$#&#%! reverb sound like it should. The answer was, "it does sound like it should, but the sound is not for surf. It was not intended to be a 6G15, but targeted for a different musician who wanted to eliminate the drip sound and instead provide a dark reverb sound.

So, all the changes in pots n pans, resistors, tubes, caps will not turn a 75-78 into a 6G15 without major surgery.

That is a fact, Jack.

Have a happy 4th Boom.

Joey G

dboomer wrote:

SurfBeat wrote:

I wish I had the time to explain when the "brand," i.e., manufacturer of a cap in a specific circuit matters, and when it does not, but I do not have the time today.

Take all the time you need. I am an engineer by trade and I fully understand the differences. In this kind of an audio circuit the difference will be 100-1000 times less than the difference you will get by changing guitar cables. Still wanna spend your money?

I will explain my position below.

Don't waste your time changing out pots, pans, (pun intended) resistors, tubes, etc. None of that is gonna' work. I guarantee it.

Then what's left to change except the faceplate?

No, the faceplate can be retained, however, the entire circuit has to be changed.

The 75-78 RU works exactly as it was designed and when it comes to being applied to the surf genre, it sucks.

Agreed, but I thought the topic was how to make is sound good in a surf sense???

It can't be done unless a major part of the circuit is changed.

For the record, boomer, (and I respond only because you mentioned vocations), I was an excellent marksman when I was a cop, I am damn good with my law books and the art or persuasion when my client is facing a judge who wants to incarcerate him, but, when it comes to anything that requires using a multi meter or the field electronics, I am a 100% novice.

Boom, the only point I was trying to make about capacitor manufacturer, which was based upon what I have read, not from any formal training which I readily admit I have none, was that when it comes to caps in the power section, the manufacture does not matter.

Contrary to my statement regarding the caps for the power section, with respect to caps in the tone section, go with USA or German made caps. I make that statement from experience when I substituted USA made caps for Chinese. When I used Chinese made caps, tone was significantly effected. When I tossed the Chinese caps and replaced them with German made caps, I got my ideal tone back.

Moving along, and being redundant, the 1975-1978 Fender Reverb unit sounds the way it does because it was designed NOT to have the "drip" that was designed into the 6G15 or post 93 RI. The CBS engineers marketed the 75-78 for a different player, not one that wanted the "drip" sound.

Therefore, based upon facts, changing the pots n pans, tubes, caps, resistors or cables, (or all), as suggested by several musicians in this Thread will not make the 75-78 produce a "surf" sound.

I only referred to myself as being the "resident expert" on the 75-78 based upon what I have learned since I first got my hands on the POS unit in 1999, (I found the invoice yesterday, $375), having several techs work on it, talking to a handful of owners, and listening to a couple, and then finally, finding a tech who had a breadth of experience working on Fender amps.

So, based upon the foregoing, if someone were to come across this Thread, then, if that person was wise, I would be the best source to provide reliable information.

Now Boom, if you think I am wrong, that is the circuit must be completely modified to get the drip,, but instead some simple mods such a changing some pots n pans, tubes, cables, resistors, can transform the 75-78 from its designed dark sound to the surf sound that all surf players seek, get Mikey's up n running using your theory.

If I am wrong, dinner is on me.

Until I am proven wrong, which I know I won't, my advice to anyone contemplating purchasing a reverb unit to play the surf genre, don't purchase a 75-78, unless, you want a hand wired reverb and have the knowledge to change the circuit and ready to spend about $100 bucks in parts.

As I pointed out previously, according to the recent (2015) price guide published by Vintage Guitar, 75-78's sell for about %500-$600, so if a person has to add another $100 bucks to that cost, plus shipping costs, common sense would indicate the wiser choice would be to purchase a RI for about $375 or a 1966 for about $700. (66's are the lowest priced, but the same chassis as a 61)

Another consideration is resale value once the 75-78 is modified; it loses its "vintage" mode, being worth far less than the purchase price and parts to modify it.

Notwithstanding the foregoing, I will be keenly watching this Thread to see if anyone is able to make the 75-78 sound like a 6G15, or fit for the surf genre, by simply changing pots, pans, tubes, rectifiers, transistors, capacitors, or whatever. Based upon my experience, it ain't gonna happen.

So Boom, I am done rambling about the POS 75-78 Fender Reverb unit, so are you coming down to sit in with my band next month? I will even buy ya lunch and some brew if you drink. We can then laugh about this exchange of ideas.

Last edited: Jul 04, 2015 14:11:52

Mikey, I praise your zeal to get that POS 75-78 RU to give you the sound you desire. I shared the same opinion and enthusiasm as you now reflect, only to be disappointed after spending money that did not get the desired results, tossing the POS in the garage for a couple of years and finding it when the boss lady told me it is time to clean out the garage, again trying to get it to give me the sound I wanted, i.e., like my 6G15. It took the fourth tech to finally get the task accomplished,

Please keep this Thread posted on your results, whether you find or do not find the solution. If the former, I am gonna raise hell with my tech who charged me $298.33 to get it to function the way I wanted, like a 6G15. Unlike you, (no disrespect intended) he is supposed to be an expert, formally trained.

I hope you get it done before the fireworks go on display tonight.

So, played around with the unit a bit tonight. I had a 12AT7 lying around so i put it in V1, I did not have any pots of lower value that I was able to get tonight, so what I did was wire a 100k resistor on lugs 1 and 3 of the 250k pot I used to replace the dwell in order to lower its value in hopes of not overdriving the unit. This allowed me to get to about 8/9 on the dial before starting to overdrive, meaning my max resistance is still too high, but this will be easy with a lower value pot when I finally get one. Another side note, i noticed not the schematic there was one .0022 cap from mixer to tone pot. Mine had two of them wired in parallel, so I removed it and left only one in its place like the schematic said (even though I did not notice much difference if any once it was gone)
Now on to the 'verb. I was able to dial in much, much more usable reverb than I was able to before any of these minor modifications were done. However, is this gonna sound like a 6G15. I can't say for certain as I have never owned or played through one, only familiar with sounds off albums,and demo's I have seen on youtube. I do think I can get a decent surf sound with this unit as it stands right now? Yes I do think so, I can try and get some sound samples up or something to give a general idea of what this sounds like through my amp, but that may not happen for a few days or any recording will likely have the sound of kids screaming and running around in the background...lol. One thing that I have noticed from the videos I have seen on 6g15's that the mixer seems to be different on the 70's units. If I turn the mixer to 10, the sound is overkill, almost too distant if that makes any sense. Not sure whats going on there, but great sounds when its set anywhere from 3-7, although I prefer it close to 5 depending on where I set the dwell.
I will keep posted on my progress. And SurfBeat, no offence taken, to me this is a hobby and not my job. That being said I am sure your tech is great and for your unit to sound like your 61, and even better then it is money well spent. I honestly can't make that comparison and it be credible as I do not own or have first hand experience playing through one of those units. All I know for sure is that the minor changes that I did make to mine, although not finalized yet, have made a very big difference in the sounds that the unit is now able to produce.

mikey3 wrote:

SurfBeat, no offence taken, to me this is a hobby and not my job. That being said I am sure your tech is great and for your unit to sound like your 61, and even better then it is money well spent. I honestly can't make that comparison and it be credible as I do not own or have first hand experience playing through one of those units. All I know for sure is that the minor changes that I did make to mine, although not finalized yet, have made a very big difference in the sounds that the unit is now able to produce.

Mikey, no offense taken. Like you, I am a novice with a multi-meter.

Now that I found my invoice for my 76, I was able to recollect I bought it for $375 on ebay from a dealer in Texas who claimed it sounded bitchin.

Unfortunately for me, when it arrived on my door step I was very busy on a case, so, I forgot about it for over a month and when i finally plugged it in and heard that "dark sound," I figured the problem lied in the 6V6 or 7025. When I checked those tubes and saw they were fine, I replaced them with the ones from my 6G615. No change.

I then surmised the problem lied with the cables - nope, then the pan - nope. I interchanged them with my 6G15, no change. When I put those items in my 6G, my 6G worked fine.

It was too late to raise hell on ebay, so, I reluctantly sent it off to a local tech. He kept it for about 6 months, then said it was the tubes. I gave him $50-$75 bucks for his time and said, adios.

The damn POS went in the garage and I forgot about it until one day I was cleaning out the garage.

Because I was told the extra 7025 gave the 75-78 a better sound, I took it to another tech. he had it for a month and gave up.

Back in the garage for a couple years when a local music shop owner joined my band. He said he had a knowledgeable tech, so I gave it to him. Over a year on his bench and he recommended changing the power caps. Did that, no change.

Back into the garage for another couple of years.

I ran into a friend who I hadn't seen in many years and I remembered he was a electronic wizard.

Two weeks later he called, said the unit plays as designed, which was not for surf. Said it needed major surgery. I gave him the ok, but passed out when he gave me the $298 bill.

Bottom line, if anyone has a 75-78 and you want to use it for surf music, sell it and get a RI, or have the knowledge to do major surgery on it. Otherwise, it will never give you the "drip" which IMO, is essential for surf music.

Just listen to Mikey's sound track and you will see what I am talking about.

Mikey, I wish you the best of luck, really.

And please keep this Thread alive to advise of your progress. If you can get that POS to sound right, you deserve a major "thata boy."

SlacktoneDave wrote:

Isn't the 6v6 {6k6?} wired differently in that Pinto Reverb? Never heard anybody acknowledge that.

Yes, it the circuit is a bit different. It is fixed biased in the SF unit and cathode biased in the 6g15. There are lots of differences in the circuits but they are very minor and easily swapped. But you have to understand what the contributions to the sound quality are. The big differences are in the drive levels, the tone shaping and the differences in breakup quality between the 6k6 and 6v6 tubes.

If you don't drive the pan hard you won't get the drip. That was purposely designed out of the SF model.

The cathode basing and bypass capacitor create pre-emphasis eq which is not in the SF. This is a simple one resistor and one cap addition.

The 6k6 is a true pentode and behaves quite differently than the 6v6 once you cross the breakup threshold. The way the SF is designed you will unlikely ever push the 6v6 into breakup. Pretty easy to go backward and drop a 6k6 in place of the 6v6 ( you can't easily go the other way though).

But none of these changes constitutes major surgery compared to changing a Pinto into a Shelby in which you have to swap out about everything except the body ( which you just modify). With the reverbs you simply change the voicings with some simple, cheap component swaps ( plus a tube swap). You don't add any additional stages which would be my definition of major redesign.

I thought you said Dick Dale gave that 76 reverb unit to you?

"I think the reason I got the 76 was when Dick Dale was relocating from Riverside to Costa Mesa and he had the damn thing in his trailer. I recall he said it was a boat anchor and when I saw the extra tube I thought it would give more punch than the 60's tanks so he gave it to me."

SurfBeat wrote:

Now that I found my invoice for my 76, I was able to recollect I bought it for $375 on ebay from a dealer in Texas who claimed it sounded bitchin.

Did some more playing around, here is the latest sound on the Silverface Reverb Unit.

Setup is Classic 50's Strat into the Reverb Unit into a Tweed Pro Junior.

I am not a 6G15 expert, nor do I have any comparisons except for what I hear on albums and youtube, but here is my latest. Thoughts?

https://soundcloud.com/user755211411/reverb-test-2

Last edited: Jul 12, 2015 22:05:27