Let's see your amplifiers...

[Michael Smith]

Your Bassman *may* be an AB165 -- the key is the build date which should be ink-stamped inside the chassis, adjacent to the P/T. Those amps built after May of '68 will likely be the AC568 circuit revision.

My Bassman has (2) 150ohm 7 watt resistors attached to the power tubes, which is consistent with AC568. Of course, it could be a hybrid or transitional build that doesn't conform exactly to any schematic. The date codes on the transformers are from 1967 and 1968, and the original cathode bypass caps and the filter caps have a date code of 1968. I can't read the date codes on the pots. The serial number seems to indicate 1969, but possibly 1968.


From Wiki:"The first Silverface amps, manufactured between 1967 and 1969, had an aluminum frame (trim, known as a "drip edge") around the grillcloth, mid-1960s "tailed" amp logo and the AB763 blackface circuit. An even rarer feature were the vertical, narrow black lines, which separated knob groups in the control panel. This cosmetic detail (later referred to as "blackline") was quickly abandoned."


The rubber stamped code on the inside of the chassis near the power transformer is 1224268, so that might suggest the 42nd week of 1968. I never noticed that before, thanks for the tip.

[Michael Smith]

Btw- I made my own circle jig for my router out of a piece of plywood. It's not very precise in the diameter of the holes it produces, but it does make a perfect circle & they are at least in the ballpark. Any rough edges are then taken care of with sand paper &/or a rasp

I have also seen people make "trammels" out of a piece of hardboard attached to the router base. Different pivot holes can be drilled to permit various speaker hole diameters. You would just drill a hole in the center of where the speaker is to go, and insert a short dowel in the corresponding pivot hole. It's best to do the routing with a sacrificial piece of plywood under the work piece to minimize tear out.

[phantomman]

The silverface Bassman head has a lot of untapped potential that a competent tech can easily exploit. The best conversion (IMO) is back-dating the circuit to the earlier brownface 6G6A guise. This mod utilizes all four stages of the bass instrument channel's pre-amp tubes for some phenomenal saturated overdrive and compression, reintroduces the enigmatic presence control, and yields a skosh more output power if the P/T is replaced with P/N 125P7A due to its higher plate voltage (470 VDC vs 425 VDC of the AB165 revision). It's a real sweet package.

[Michael Smith]

The silverface Bassman head has a lot of untapped potential that a competent tech can easily exploit. The best conversion (IMO) is back-dating the circuit to the earlier brownface 6G6A guise. This mod utilizes all four stages of the bass instrument channel's pre-amp tubes for some phenomenal saturated overdrive and compression, reintroduces the enigmatic presence control, and yields a skosh more output power if the P/T is replaced with P/N 125P7A due to its higher plate voltage (470 VDC vs 425 VDC of the AB165 revision). It's a real sweet package.

I did notice looking at the AC568 schematic that they only use 1/2 of V2 (or maybe it's V3), so I assumed someone came up with a mod to add some gain. I actually mainly use this amp head for bass guitar, so clean headroom is what I need. It had been sitting idle in my studio for about 6 years until about this time last year when I fired it up and quickly "blew" a filter cap. Luckily no other damage was done. That's when I decided to replace all of the electrolytic caps and certain resistors. I should have used F&T caps, but wasn't that knowledgeable at the time. On my more valuable amps I did use F&T's for all of the filter caps. I used metal oxide 2 watt resistors in the doghouse and bias section.

I have a couple other vintage Fenders I have been working on, but will probably take better photos with a real camera and a tripod after noticing how sorry some of the photos I have posted look.

[Cogs]

I had to use google to learn what a "trammel" is, & I've basically produced a crude version that I attach to the router base. Kind of a compass with a screw for the stationary center & the outside edge of the router bit for the radius.

[Michael Smith]

I had to use google to learn what a "trammel" is, & I've basically produced a crude version that I attach to the router base. Kind of a compass with a screw for the stationary center & the outside edge of the router bit for the radius.

Ya, you could use a screw for the pivot point or drill a hole in the trammel and the work piece and insert a short piece of dowel. You would just have to take some careful measurements before drilling the hole in the trammel. The one's I have seen on the internet are kind of narrow triangular shaped, with the wide end attached to the router base, and the smaller end is the pivot point.

[DanTheBluesMan]

I like the idea of a Princeton non reverb head. I have the Radio Shack version of that orange frame speaker, I think. Was that a JBL or a Utah?

[phantomman]

I actually mainly use this amp head for bass guitar, so clean headroom is what I need.

I understand.

In that case the best way to maximize any Bassman's stage-performance potential is to examine the various speaker-system options. A great upgrade would be a 2 x 15 folded-horn enclosure containing a pair of JBL D140F's such as Sunn's 200S or 190B cab. They also work extremely well as bass rigs with Fender's Dual Showman head.

[Michael Smith]

I bought this Peavey 2 x 15 bass cab used in the early 1990's. It's way too heavy to get up and down 17 stairs from my studio, so it hasn't moved from there in over 25 years. For gigging I built a 1 x 15 cab with a horn. Still heavy, but more manageable. I had another pawn shop special, a Bassman 135 Master Volume Amp, which I sold a few years ago to a buddy, (for far too little by today's standards). It paired well with the 2 x 15 Peavey.

[Michael Smith]

Do the forum rules allow us to say what we paid for which amps in past years? If so, I have some detailed info.

[OldStrummer]

Do the forum rules allow us to say what we paid for which amps in past years? If so, I have some detailed info.

I am not aware of any restrictions on talking about price.

[Don]

Do the forum rules allow us to say what we paid for which amps in past years? If so, I have some detailed info.

No rules against that.

[Michael Smith]

I am not aware of any restrictions on talking about price.

Good to know, just thought I'd ask first. With the popularity of online auction sites, or just online information in general, the price of used amplifiers seems to have gone crazy in the past few years. I've been in the process of scanning into my computer, all of the receipts I can find for the musical gear I have bought over the years. I also ran across a website that has links to old Fender catalogs and price lists, although there are quite a few gaps before the late 1960's. Here's what I came up with for the amps I purchased and have already shown photos of earlier in this thread. The list prices are from the online price lists I found corresponding to the year I believe my amps to have been built.

Bassman 50 Watt head, Listed for $270 in Oct, 1968, I paid $100 in January, 1988. (Pawn Shop in Houston, TX).
Bassman 135 Watt head, Listed for $390 in Sept, 1978, I paid $180 in April, 1993. (Pawn Shop in Houston, TX). I sold it for around $250 about 10 years ago.
Super Twin Reverb, Listed for $745 in April, 1977, I paid $400 in April, 1993. (Pawn Shop in Houston, TX).
Vibro Champ, Listed for $155 in Sept, 1979. I paid $150 for it brand new (Tulsa, Oklahoma) in August, 1979.

When I post photos of my more recent purchases, I will include this same information, in case anyone is interested. I'm not looking to buy or sell any amps, just thought this information is interesting.

[phantomman]

I remember when a blackface Princeton Reverb retailed for $179.50 (the non-verb model was $159.50).

I wish I'd bought a dozen.

Who knew?

[Michael Smith]

I remember when a blackface Princeton Reverb retailed for $179.50 (the non-verb model was $159.50). <br>
<br>
I wish I'd bought a dozen.<br>

Who knew?

<br>Or a few 1957 Strats. Here is a page from Fender's Feb, 1957 Price list. It's kind of hard to read and I couldn't convert the pdf into an image file so I took a picture of it on my computer monitor in order to upload the photo to an image sharing site.

By the way I found the Fender price lists on a site called "guitar-compare.com"

[phantomman]

Twelve years ago I bought a blackface Princeton Reverb Amp from a local gentleman who was the second owner. Cosmetically it was a 9.5/10.0 but needed the usual servicing (cap can, power rail resistors, etc), modern safety upgrades, and a speaker. LBJ was the president when this amp was built and I paid $640 for it plus a couple of hundred in restoration costs. A small but significant victory.

[Michael Smith]

Twelve years ago I bought a blackface Princeton Reverb Amp from a local gentleman who was the second owner. Cosmetically it was a 9.5/10.0 but needed the usual servicing (cap can, power rail resistors, etc), modern safety upgrades, and a speaker. LBJ was the president when this amp was built and I paid $640 for it plus a couple of hundred in restoration costs. A small but significant victory.

You got a very good price, compared to today. I looked at Reverb's price guide for 1965 Princeton Reverbs and most are selling in the $3,000 to $3,500 range, with some in the $4,000 plus range.

[phantomman]

Indeed. My profit should pay for a month's worth of care in a nursing home.

[Michael Smith]

Here's something I just noticed from looking at the old Fender price lists. The choice of speakers made a BIG difference in the price of the amp. For example, from the 1973 price list for the Twin Reverb Amp. The price for the amp with the standard Fender speakers, $575, JBL speakers, $720, Fender PS speakers, $758.

For the Super Reverb, the standard speakers $500, JBL's $748.

Super Six Reverb, Standard $650, JBL's $1,135.

Are the JBL's or PS speakers really worth the premium?

[phantomman]

I think so at least in the case of the JBL's. But it really depends on the amp. For Super Reverbs (or any amp with 10-inch speakers) I prefer the CTS alnico's OR the Fender-marked Jensen C10NS drivers. Bandmasters and Pro Reverbs sound their best with vintage C12Q's or C12NA's. Fender's PS series speakers (actually made by Cetec/Gauss) are a bit of a mystery to me, never having played or owned any. Apparently they're similar in design and performance to the EV-SRO speakers. For solid Fender punch the D-series alnico JBL's really deliver, at least for my purposes.

[Michael Smith]

I had never heard of the Fender PS speakers until now. I looked them up on Reverb, and they are quite pricey. Looks like I have a lot to learn, and this forum should be a good source. Tomorrow I plan to post photos of a Fender Amp I own that no one will get excited about, but it serves it's purpose.

[phantomman]

I've had a relationship with Fender gear for fifty-five years and I'm still learning things.

[jrgtr42]

I haven't paid more than $1000 for any of my amps - and most have been significantly less.
|Probably best apprciation is my '66 Vibro Champ. I got it for $400, I think, about 15 years ago. There's a couple on Reverb now for $1600 or so. I don't know how much, if anything, changing the cord to a 3-prong, and re-capping affects the value, but it would still be significant profit. If I was considering selling it, that is.
I have a 1975 Marshall JMP that I paid |I think $700 or so for. Kinda staggered seeing prices on those. Mine has a master/gain mod, though, so again I don;t know how that affects the value.
I can't believe that JCM 900s are over $2000 new these days. Mine probably wouldn't get that much, even though it is in great shape.
Not gonna talk about my others, since they tend to be off kilter things.

[Cogs]

We used to have a policy prohibiting the posting of prices, but that was specifically to protect forum sponsors. You can imagine what could happen if a dealer gave someone a "bro price" & then that price was posted in a public forum.

[Michael Smith]

These photos are of a 1988 Princeton Chorus solid state amplifier. It is equipped with (2) 10" Eminence speakers dated the 46th week of 1988. It is a true stereo amp, delivering 25.5 Watts RMS per channel. Each channel can be fed into a mixer using the stereo send on the effects loop. According to the manual, it weighs 38 pounds. The clean channel sounds very good and is loud!. The overdrive channel does not sound very good (in my opinion). It has a spring reverb and a footswitch to select the overdrive channel or the chorus effect. These can also be selected using switches on the front panel.

I use this amp from time to time when I want to practice at a low level, on the clean channel. It sounds best with a Strat or Tele. I imagine it would work well with a pedal steel guitar. I sold my pedal steel before I bought this amp, so never tried it. I do have a cheap lap steel that I may try it with.

The October, 1988 price guide lists this amp at $440. I paid around $225 for it in the late 1990's or early 2000's in a private sale from a guy who had it listed on our company's employee marketplace website. I haven't looked up the current value of the amp, but I don't imagine it is worth much. I could probably part it out, as the cabinet, speakers, reverb tank and red knobs may have some value.

[phantomman]

The worst aspect of those amps was the hideous cosmetics (WTF was Fender thinking?).

That said, those dwindling few amps left are now long in the tooth and no longer logistically-supportable. Specifically, there are several proprietary (and critical) IC's made by Panasonic used in the effects-switching and output circuits which are no longer manufactured and (to my knowledge) no equivalent substitutes exist.

[Michael Smith]

The worst aspect of those amps was the hideous cosmetics (WTF was Fender thinking?).

That said, those dwindling few amps left are now long in the tooth and no longer logistically-supportable. Specifically, there are several proprietary (and critical) IC's made by Panasonic used in the effects-switching and output circuits which are no longer manufactured and (to my knowledge) no equivalent substitutes exist.

If and when it dies, I would probably just rewire the speakers and use it as a 2 x 10 cabinet. Or maybe install a kit built tube amp chassis in it. It looks like everything is made of particle board, and is in very good condition now. The speaker baffle looks like its glued in, so if I ever wanted to install a different baffle, I would have to cut this one out and install some cleats for a new baffle. As little as I use it, perhaps it will outlast me, lol.

[phantomman]

You have a solid grasp of the situation. They were reliable and adequate for their time but that era has long since passed. Enjoy it at home as a garage-jam amp but don't rely on it for a live, paying gig. If it goes tits up there, so do you.

[Michael Smith]

I remember a friend of mine using one of these for a gig when his tube amp was in the shop. With the pedals he was using, he got a good sounding blues distorted sound. I have never had much luck getting a good sound out of my Princeton Chorus with pedals, but I'm no expert. I've been organizing my amp photos, and hopefully tomorrow will post some of a "real" amp, lol.

[phantomman]

Got any "tweed"?

[Michael Smith]

Teaser (but probably not what you were hoping for).

[Michael Smith]

I wasn't going to post these photos until I covered all of my Fender amps, but since I teased it... Amp was purchased new from Carvin in Sept, 2010 for $369. It has two EL 84's and three 12ax7's. One nice feature is there are test points inside the chassis where you can measure and set the bias. You just have to move a spade connecter from one terminal to another. It came with a Carvin GT12 100 Watt speaker, and I didn't like the sound of it. Also tried a Celestion Vintage 30 and didn't like that either. Then I put in about a 10 year old Jensen C12Q that was in one of my other Fender Amps and it sounds a lot better, breaking up at lower volume. I think that is a 35 watt speaker. There is a switch on the rear of the channel that switches between Pentode 16 watt mode and Triode 5 Watt mode. I haven't found that to be very useful, and don't hear much difference. The cabinet is solidly built and the tweed is nice. It probably wouldn't pay to have it repaired when something on the pcb dies, but the chassis might make a good place to build a point to point low wattage amp. Someone has published a list of modifications that supposedly really improve the amp, but I haven't done any of them. It also has a spring reverb, although I understand later versions may have used a digital reverb.

[phantomman]

You've got some good glass there......Sovtek's are some very fine bottles.

[Don]

I wasn't going to post these photos until I covered all of my Fender amps, but since I teased it... Amp was purchased new from Carvin in Sept, 2010 for $369. It has two EL 84's and three 12ax7's. One nice feature is there are test points inside the chassis where you can measure and set the bias. You just have to move a spade connecter from one terminal to another. It came with a Carvin GT12 100 Watt speaker, and I didn't like the sound of it. Also tried a Celestion Vintage 30 and didn't like that either. Then I put in about a 10 year old Jensen C12Q that was in one of my other Fender Amps and it sounds a lot better, breaking up at lower volume. I think that is a 35 watt speaker. There is a switch on the rear of the channel that switches between Pentode 16 watt mode and Triode 5 Watt mode. I haven't found that to be very useful, and don't hear much difference. The cabinet is solidly built and the tweed is nice. It probably wouldn't pay to have it repaired when something on the pcb dies, but the chassis might make a good place to build a point to point low wattage amp. Someone has published a list of modifications that supposedly really improve the amp, but I haven't done any of them. It also has a spring reverb, although I understand later versions may have used a digital reverb.

I've always wanted one of these, but my portable 12-20 watt 1x12" combo needs are well covered. I've had a Carvin Vintage 33 1x12" combo and an early Vintage 50 head and matching 4x10" cab. They were both pretty good sounding amps. The early VT50 had traces running too close to each other on the power tube PCB that often lead to disaster. I had to do a pretty major repair in mine.

Btw, you are correct, Carvin eventually used digital reverb in these amps.

[Michael Smith]

I have had good luck with Sovtek tubes. My Super Twin Reverb has a matched quad of Svetlana 6L6's. I think they are made in the same factory, but not 100% sure of that. Phantomman, if you like Sovtek stuff, stay tuned for a future post I will make.

[Michael Smith]

1969 Fender Super Reverb. List price in Oct, 1969 $475. I paid $1,400 in March, 2021 from a private seller. I believe it is circuit AB568. All electrolytic caps were original. I changed them out and installed metal oxide resistors in the doghouse. It had a 5AR4 rectifier tube, but I installed a 5U4GB to conform to the AB568 circuit. The amp is cosmetically in very good to excellent condition. One of the CTS speakers was reconed just prior to me purchasing it. I doesn't look like it was heavily gigged, if at all, but it must have been kept in a smoky environment. The second picture is halfway thru cleaning the grill cloth. I used a product called "Oxygen Power" with a soft toothbrush, then rolled up a damp towel and rolled it over the surface of the grill cloth. The first couple of times the water wrung out of the towel was yellow/brown. Also, there was residue from a sticker on the lower back panel that I used WD-40 and a toothbrush to remove.

[phantomman]

Got any pics of the innards?

A shot of the bias circuit will provide definitive identification of the specific circuit revision.

[Michael Smith]

Got any pics of the innards?

A shot of the bias circuit will provide definitive identification of the specific circuit revision.

I don't have any great "before" shots of the bias circuit, but I have the old cap and resistor, and didn't change the diode. What information would be helpful?
Edit: The more I look at my circuit and compare it to the schematics, I'm pretty sure its NOT AB568. On AB568 pins 8 of the power tubes have 150 Ohm 7 watt resistors and are joined to ground via a 5 Microfarad/25 volt non-polarized cap. On my amp, pin's 8 are soldered directly to ground. Also on my amp there are no 2000 Picofarad caps connecting pins 5 of the power tubes to ground, as is shown on the schematics for AB568, AA1069 and AA270, but NOT on AB763. There is evidence (blobs of solder on the chassis near pins 5 of the power tubes) on my amp that suggests there may have been the 2000 Picofarad caps there at one time, and perhaps someone removed them to make the amp like AB763.

The negative bias cap that I removed from the amp was 50 Microfarad/70 volts (dated the 31st week of 1969), and the bias resistor was 1K, consistent with AB568. AB763 used a 470 Ohm and AA1069 used 1.8K. I replaced the cap with a 100/100 and the resistor with a 1.8K.

So much more study of the schematics and perhaps a detailed drawing of my amp may be necessary. One thing I did notice on this amp is the wiring used is thinner than my other Fenders from around this time, and the lead dress is quite sloppy.

[Cogs]

Killer amp to be sure. Looks clean as a whistle. A '71 Super Reverb was my main amp from 1981 to 1999. I only retired it to work on the cabinet, & that's about the time I bought my Bandmaster, so I didn't get back to it.
The Super was in such bad shape that I had to cradle it in my arms during load-in/load-out. Once after a gig I went to pick it up & the only thing that moved was the handle, the top panel, & the chassis. The power cord, & reverb & speaker wires were just dangling down into the remainder of the cab. I knew it was time to renovate, lol

[phantomman]

It appears that the bias-supply circuit has been back-dated to AB763 specs (a good thing).

The wiring looks thinner but that's only because the insulating jacket is vinyl rather than the earlier cloth push-back type. It's still the same AWG18 conductor.

What speakers are installed?