Articles/Electronics/Other/Unmasking Fender Silverface Amps

by Frank Stroupe

***WARNING-There are voltages inside of a tube guitar amp that can KILL you. There are components in the amp that hold live current long after the amplifier is unplugged. If you are not familiar with working on vacuum tube equipment, you should consult an experienced technician before opening any equipment containing vacuum tubes. This article is for informational purposes only. The Free Information Society will not be responsible for any injury or damage caused to you or your equipment.***

Early Silverface Logo on Standard Silverface Grillcloth

So, you've heard all of your guitar playing life, whether it be for 2 years or 25, that you don't want a Silverface Fender amp.

I can't say today that they are the "best kept secret", because over the past few years, the prices on them are steadily obviously, the secret has gotten out. That MusicMaster Bass amp or Silverface Champ that you could have bought all day for 50 bucks as recently as 2 years ago can run as high as 350-400 on ebay now. Though, hopefully no one will bid on those that are that high. Other silverface amps have similarly appreciated. But, they are still available at killer prices, if for no other reason, there are many of them still available...many a silverfaced amp was passed over in the 80's and 90's by someone that HAD to have a tweed or blackfaced one. I recently purchased a 1972 Silverface Champ for 40 bucks.

I am not an expert on amps, Fender amps, or Silverface Fender amps. Nor am I a tech. I am merely someone that loves old gear, appreciates Silverface amps, loves to write, and loves history. So, here I am, writing about the history of some old gear, the Silverface Fender. I also have a small amount of knowledge of and experience in working on tube amps.

This is intended to be an informative article for the uninformed, and is purposely not terribly specific. I'm also not going to get too deeply into technical details of circuitry. I apologize in advance if I got a date wrong, a model wrong, etc. Its pretty hard to get extremely accurate information on the history of Fender amps...for several reasons...and someone will always criticize the specifics.

I also apologize for not having a lot of photos of mint Silverface equipment. Presently, I personally own only two well worn Silverface road warriors, a 1971 Champ, and a 1972 Bassman 50 (AA371). Both had seen many miles by the time I got them, and I've added a few more to the Bassman in the nearly 20 years that I've owned it. Actually, when I bought my head, it was in a Blackface box...which confused me for a long time until I realized what had happened. I have a few other jpegs of other silverface equipment I know the owners of. I suppose I could have ripped off some photos from other websites, but that's not my style. If you need to see them, Google the Fender Field Guide.

My 1972 Champ

What the heck is a Silverface?

Quite simply, a Silverface Fender Amp is an amplifier made by the Fender Musical Instruments Company from late 1967 to 1983. They are called "silverface" due to the brushed aluminum look of the faceplate. Much more on this later.

So, why don't I want one?

I suppose that if you compare Silverface equipment to its earlier tweed and blackface brethren, the silverface amps are in many cases not that great, and that is the justification that has been used for a couple of decades by Silverface critics. Do a quick look on ebay, eliminate the ridiculously high opening bids that no one else has bid on, (which in case of the search I just did is well over half of them) and you'll find that in most cases you can expect to pay about twice as much for a Blackface than a Silverface, and at least three or four times as much for a tweed. (5 or 6 times as much in the case of a tweed Champ vs a silverface one) Face it, tweeds are actually museum artifacts, and if you find any genuine tweed Fender for under a grand, buy it and consider yourself extremely lucky, and I'm not going to compare Silverface equipment to tweed.

Personally, I would rather compare Silverface equipment to what is available today. Take the Silverface Champ. It is a great sounding little amp, and you can usually pick them up for under $200. Where else are you going to find a tube rectified, single ended, hand wired, 6 watt (and a very strong 6 watt) amp for $500, much less $200? Yes, silverface amps are hand wired. I have an Epiphone Galaxie 10 that I was given for Christmas. It is a 10 watt (maybe) single ended tube amp, with solid state rectifier, printed circuit board (PCB), and cost $ isn't as bad as some PCB amps, because the tube sockets are attached to the steel chassis and not the board itself. It is a pretty cool little amp, and I really liked it. Until I A/B'd it against my Champ. I don't think it has been plugged in since...the Champ was louder, and sounded MUCH better. (I'm not knocking the Galaxie...I still think it is a great little amp, especially for the price...I think that Gibson made a mistake discontinuing just needed a little improvement)

I mentioned that the Champ is hand wired. Actually, it is pretty incredible, if you really think about it, that Fender was still hand wiring all of their tube amps in 1982. For that matter, you can often pick up Bassman or Bandmaster heads for under $300...where are you going to find a hand wired 50 watt head for that? Where are you gonna find one for $1000?

And, silverface amps are built like tanks. The cases are heavy pine plank and/or marine plywood, with dovetailed corners, the transformers are huge, everything is overkill.

1971 Twin Reverb

Some background information

Leo Fender, who was in poor health due to overwork, along with his partner, Don Randall, sold his beloved "Fender Electric Instrument Company" to the Columbia Broadcasting System (CBS) in late 1964, with CBS taking over in early 1965, and changing the name of the company to "Fender Musical Instruments". Pretty much for the first 5 years, CBS didn't make that many changes to the amp circuits in production when they took over, and kept the current cosmetic scheme, a black faceplate with white lettering, black tolex (which Fender had changed to in 1964) and a bone colored grillcloth with black and silver threads in it. But, there were a few changes here and there, some models were discontinued during that time...such as the Concert and Pro in 1965 and the Deluxe in 1966.

In late 1967, Fender changed the cosmetics of the faceplate to a brushed aluminum look with blue and black lettering, and the grillcloth was given a blue "sparkle". There were a very few cosmetic changes made between 1968 and 1980. For the next few years, many models received mods to the current circuits, and in some cases totally new circuits. Probably the biggest change made by CBS was going from a true "bias pot" to a "balance pot" on the class A/B amps. A little more on that later.

(Unlike many others) I don't profess to know what CBS was doing, why they went the direction they did with the circuits. Most changes generally made a louder, cleaner sounding amp, with more headroom. Of course, during this time, rock musicians were seeking more and more distortion. Don Randall obviously didn't agree with what was going on, as he resigned his general manager position in mid-1969.

Around 1970, there was a music store that I would stand in front of often, slobbering at this silverface Dual Showman Reverb with two cabs that they had in the window. It just looked so massive. A few years later, when I actually started playing the guitar, that amp was dream was of a Marshall full stack. By that time, no one was using Fender amps, except for Ted Nugent, and he was in a class by himself anyway. From probably 1976 to the early '80's, I really don't even remember seeing a Fender amp in a music store, much less on stage.

Between 1968 and 1972, reverb and vibrato was added to several models, and master volume was added to a few. By mid-1976, most Fender amps 50 watts and over had a master volume. I guess it was a too little too late attempt to draw some rock musicians over. That December, the movie "Saturday Night Fever" was released, the "disco" era began, and most musical instrument manufacturers suffered to some extent. Many closed their doors in the late 1970's. Though, I will say, during that time, I saw a fair number of DJ's using Fender column PA systems, so they were selling at least some amps.

In 1980, Fender went back to blackface cosmetics. The silverface models that continued through this period are still considered silverface amps, the new models introduced through this period are generally called "Rivera" Fender amps, and begin a new era of Fender amps. By the end of 1983, all silverface amps were discontinued.

Later Silverface Logo

Blackface vs. Silverface

So what's different between the amps of the blackface era, and the silverface era. As I have already mentioned, probably the most important change was going from a bias adjustment pot on the blackface amps, to a pot that allowed one to balance the bias between the two tubes...or pairs of tubes on the larger amps. This was done to help eliminate hum, mostly from poor circuit design and sloppy manufacturing processes. Probably the biggest reason was to allow for using pairs of unmatched tubes. By the late 1960s, the quality of tubes from American manufacturers had dropped greatly, mostly due to poor quality control. The balance pot compensated for that, thus eliminating the need for going thru countless tubes to get matched ones. The problem with the balance pot is that attempting to reset the bias after replacing tubes became a major undertaking.

Another change for the silverface amps was that voltages increased pretty much throughout the circuits. Not a terrible thing in itself, but keeping in mind that Fender was obviously looking to keep the amps clean, other changes had to be made in the circuits to compensate...usually in weird feedback and negative feedback loops...which took more of the beauty from the tube tone.

And the above caused other problems...a major one being oscillation. To compensate for that, many circuits had "snubber capacitors", small value capacitors run across the power tubes to filter out some high frequencies. Many people feel that these kill the "sparkle" that was common to the blackface amps.

And, there were other changes. Fender got away from using Mallory capacitors to using "chocolate drop" capacitors, which many feel just don't sound as good. By the late '70's, they had changed to using ultralinear output transformers, which increased output wattage, but also increased voltages in other places in the amp. They started putting master volume pots on some models in 1972, any by the end of the decade, pretty much all larger models had a master volume, some with push-pull pots, "pull for gain". Also, Fender changed brands of speakers that they used over the years, even Leo did. By the '70s, excepting the few models that had JBL speakers, CBS Fender used some pretty crappy speakers. It is extremely common to find silverface equipment with speakers that were replaced with non-standard ones 25 years ago.

1976 Dual Showman Reverb

So how do they sound?

I can't sit here and truthfully say that silverface amps sound as good as blackface, though the 6 and 12 watters pretty much do. The bigger amps don't sound bad, many of them just don't sound great, especially when compared to their blackface ancestors, which I've already said cost twice as much. I have heard for many years, "don't get the ones with master volume", "don't get the ones with ultralinear", "don't get this", "don't get that"....mostly "don't get silverface". Most of these people with the warnings, when asked, actually had never personally owned a silverface Fender. "I know better."

But, talk to someone that has owned one...especially someone that had heard all of the warnings often as not, they will tell you how surprised they were to discover how good a silverface really sounds. I have personally been told by more than one person, that after swapping the speakers, their large silverface sounded great, and they couldn't believe that they bought all of the bad info they had been given over the years.

The small amps have that tube tone, regardless of what you've heard. They all (if working correctly) pretty much are clean up to "5" or "6"...and everything after that is compression and distortion. The larger amps have a lot of clean headroom...which is obviously what Fender was shooting for. If there is nothing in your sound chain between guitar and amp but a cord, and you like pure tube won't go wrong with any of these amps.

Later Model MusicMaster Bass Amp

The small amps

I guess that the best tone found in silverfaced amps are in the small ones...but isn't that true for most amps? The Champ, VibroChamp, Bronco, (6 watts) Princeton and Princeton Reverb (12 watts) retained tube rectification throughout the '70's. There were a few small changes made in them, but both retain basically the blackface circuit throughout the silverface era. The MusicMaster Bass amp (12 watts) was introduced in 1970 as a 12 watt bass practice amp. IMO, it is totally worthless as a bass amp, but is a little guitar tone monster. All three have a similar tone, IMO, with the Champ sporting the most distortion. Though both the Princeton and the MMB are class A/B 6V6 amps, they share very few other similarities in their circuitry. The VibroChamp is the most desired of the bunch, and usually fetches the most cash, but to be totally honest, I have never played through one, and I really don't remember hearing anyone else doing so...I'm personally not a big fan of vibrato/tremolo in amps.

A little further up the chain, there is the Deluxe Reverb (22 watts). The Deluxe, which probably is my most favorite Fender amp, was discontinued in 1966, and the Deluxe Reverb replaced it. Other than sporting a pair of very "hot" 6v6's, there are few similarities in the two, the DR just doesn't sound quite as good as the original Deluxe, but close. But, I promise you, it blows away the '65 Deluxe Reissue, or a Hot Rod Deluxe.

The bigger amps

Next we get to the 35-70 watt amps, which included the Pro Reverb, Super Reverb, Vibrolux Reverb, which were all combo amps, and the Bandmaster and Bandmaster Reverb heads. All of these amps sported twin 6L6GC power tubes, and were rated between 35 and 50 watts. (70 watts by 1976 after the circuits were changed to ultralinear) All of these amps had one thing in common...they were LOUD...and generally clean. They all had a master volume added by the late '70's.

The main problem with all of these amps is clean headroom. By the time the 6L6GC's start giving some decent compression and distortion, you are pretty much at window shaking levels. Though, any of them would be excellent if you are using stomp boxes or effects processor.

1972 Twin Reverb

The big boys

Armed with a quad of 6L6GCs, the Twin Reverb and Super Six combos, and the Showman 15, the Dual Showman, and the Dual Showman Reverb heads, were and are capable of earth shaking, ear bleeding clean volume levels. They were rated at 85-100 watts, and the ultralinear ones were at 135 watts. If you are looking for distortion from these babies, unless you are playing a huge outdoor venue, your audience will definitely experience some hearing loss...and if you don't use ear protection, you will too. The later versions do have a master volume, and is capable of some distortion, but if you use pedals, there's no need for it, turn it to "10" and control the volume with the regular volume pots. A Dual Showman Reverb, coupled with a pair of cabinets, is an impressive display indeed. Some people pull a pair of tubes to get a more manageable volume from them, but they are still very loud.

The ridiculous and the sublime

For whatever reason, Fender built some models with a complement of six 6L6GCs, the Super Twin Reverb and Super Twin Reverb combos, both rated at 185 watts. Why someone would want a 185 watt combo, I have no idea, except for maybe heating a small home in the winter, and maybe doing a show on the flightline of an airport. I have never personally heard either, but I imagine that there is zero distortion gained from these amps.

My 1972 Bassman AA371 with blackface grillcloth on head and non-standard grillcloth on 2x12 cab

The Bassman

The Fender Bassman amp was first introduced in 1952 as amplification for Fender's newly invented Precision Bass. It went through several changes through the '50's, with various circuits and speaker configurations. By the end of the decade, it sported 4-10" speakers, solid state rectification, and around 50 watts, and open-backed cabinets. To later standards, all of these amps made fairly poor bass amplifiers, but keep in mind that the electric bass was replacing the upright bass...which was very percussive, and did not have the "booming" bass sound that came later. Sometime in the early 60's guitar players decided that the Bassman made an excellent guitar amp. The final version of the "tweed Bassman", the 5F6-A, became very desirable, and people began copying the circuit with some slight modifications, and marketing these as guitar amps, most notably Jim Marshall of Marshall Amplification.

In the early '60's, Fender went to a head/cab configuration, first with tube rectification and 1x12" speaker, then solid state rectification and 2x12". The Blackface Bassman amps had three circuits, the AA864, which many consider the best post-tweed circuit for use as a guitar amp, the AA165, the last Bassman with an actual bias pot, then the AB165.

The AB165 circuit continued throughout the Silverface era, receiving a master volume and ultralinear output transformer in the later models. Other circuits are AA568, AC568, AA270, AA371, and probably others. Fender changed to a 2x15" cab in 1968, and the speaker brands varied as mentioned above. JBL's were offered as an option for most of the '70's...a very much desired cabinet.

In 1968, Fender introduced the Super Bassman, a 100 watt Bassman, later called the Bassman 100. In 1972, the Bassman 10 was introduced, a 50 watt 4x10" combo with master volume...the circuit of the Bassman 10 was totally different from any other of the 50 watt Bassman models, and finally, in 1982, the last new Bassman in the Silverface era was added, though with Blackface cosmetics, the Bassman 18 watt 1x15 combo, sporting 2 6V6 power tubes. Personally, I have never seen one of these, but would love to try one.

I decided to put the Bassman in a section by itself, because the different circuits are so confusing. In 1972, if you walked into a store and bought a Bassman 50, you could have gotten any one of at least 5 totally different circuits, most of them sounding somewhat different, yet all were called "Bassman 50". Most of the changes in the circuits were different feedback and inverse feedback loops, and changes in the phase inverter circuit, obviously to limit distortion for a cleaner sound. Not a bad thing for a bass amp, but not so great for guitar.

So, how do you know which circuit an amp is? The Fender factory was notorious for just slapping the first available tube chart in a head...and supposedly it is extremely common for the tube chart to be the wrong one. The only real way to tell is to actually look at the circuit and compare it to various Bassman schematics. ***See the warning above***

The Bassman heads were mostly overlooked by guitarists throughout the 1970's, it just wasn't as versatile as most of the other amps out there. Even after a master volume was added, the Bassman didn't have the crunchy distortion desired by rockers. Then comes along Stevie Ray Vaughn. SRV was always in search for the perfect tone. When he mentioned in a few interviews that he used a Blackface Bassman head in his setup, suddenly the Bassman head became popular with guitarists. Of course, being much cleaner than the Blackface, the Silverface Bassman was much less desirable.

So, how do Silverface Bassman amps sound? With the exception of the early AB165, they have tons of clean headroom. My AA371 finally starts getting some distortion at window vibrating levels, but it is a nice distortion. Of all of the Bassman 50 amps, it is supposed to be the most clean. If you use pedals or processors, the inherent cleanness is fine...letting your effects do the work, just adding some tube warmth to the process. The AB165 distorts much earlier than the other models, and is by far the most desired of all of the circuits. Also, it is "blackfaced" easier than the other Silverface models.

Blackfacing Silverface Fenders

If you have shopped or researched Silverface amps at all, you probably have come across the term "blackfacing". Simply, blackfacing is modifying to some extent the circuits in a Silverface amp to the specs of those in a Blackface. It may involve simply changing the values of capacitors and/or resistors, or actual changing of the circuit itself. The only true "blackfacing" involves scrapping the entire circuit and rewiring the amp to the AA 864 or AA165 circuits, in the case of Bassman amps. Generally, there is very little blackfacing that can be done to the later Silverface amps, those with ultralinear output transformers, the voltages are just too high. Short of replacing the OTs, anyway.

Be aware, that there are people out there selling amps claimed to have been blackfaced, that very little changes have been made to. Generally, to blackface a Silverface amp, the bias circuit is rewired to a bias pot instead of a balance pot, the phase inverter circuit is rewired, feedback circuits are eliminated, and inverse feedback circuits are changed to resemble those of the Blackface amps. Usually, there are extensive changes made to the circuit to accomplish true blackfacing, in many cases, even changing from solid state rectification to tube rectification.

If you are truly interested in blackfacing a Silverface amp, a Google search will find you numerous sites with information and instructions on blackfacing.

In conclusion....

Having said all of the above, Silverface Fender Amps are actually all pieces of junk, and should be sent to me for proper disposal, to prevent harm to the environment. Please notify me in care of The Free Information Society, and I will tell you where to send your expense, of course.