Silverface Pro Reverb: 40, 45, or 70 watts?

[jman72]

Just a curious question that I've had for a while that I'm sure somebody can easily answer.

I have a Pro Reverb that, according to the chassis date code, is a 1977 model. The rear faceplate clearly says "45 WATTS RMS", and it has a 5U4GB rectifier tube. Now, all I can find anywhere online is that Pros were typically 40 watt amps up until around '76 when they were changed to the ultralinear 70 watt versions. However, I've seen schematics for 74'-75' Super/Pro/Bandmaster that are 45 watt versions with the 5U4GB rectifier.

I know that Fender often had transitional amps that had characteristics of different models, but were they really THAT all over the map in the mid/late 70's so that in 1977 they had both 45 watt and 70 watt models on the market two years after they supposedly transitioned to the ultralinears?

Just curious...

 

[corliss1]

No, the models changed pretty consistently, but the back plates may not have. You'd have to check and see if you have an ultralinear OT to be sure.

 

[Wally]

If you have a 5U4 rectifier, you do NOT have an untralinear Pro Reverb.
the UL Pro Reverb…all UL amps in fact…have a solid state rectifier. That is necessary since they run large capacitance—-110mfds—-in the first stage…..far beyond the ability of a tube rectifier. My thought was that Ultra Linears were introduced in 1977.
IF your amp has a serial number with an A 6 followed by six digits, you have a 1976 or later amp. A6xxxxx is 1976, A7xxxxx is 1977. If there are only five digits following the A, you have a 1975 or earlier amp.

 

[jman72]

If you have a 5U4 rectifier, you do NOT have an untralinear Pro Reverb.
the UL Pro Reverb…all UL amps in fact…have a solid state rectifier. That is necessary since they run large capacitance—-110mfds—-in the first stage…..far beyond the ability of a tube rectifier. My thought was that Ultra Linears were introduced in 1977.
IF your amp has a serial number with an A 6 followed by six digits, you have a 1976 or later amp. A6xxxxx is 1976, A7xxxxx is 1977. If there are only five digits following the A, you have a 1975 or earlier amp.

The serial number is A7xxxxx, which makes it a 1977. I had read in different places that the ultralinear started in '77, but I'm not certain of that.

 

[68goldtop]

Hi!

The serial number is A7xxxxx, which makes it a 1977. I had read in different places that the ultralinear started in '77, but I'm not certain of that.

Yes, I'm also quite certain that they did start in ´77, but I'm not sure when they did...
Actually, your "old style" ´77 Pro seems quite a rare find!

Btw. - the "UL"-Pros/Supers/Bandmasters... are easily identified by the mid-control on the normal-channel (4 controls instead of 3...).

cheers - 68.

 

[Ten Over]

The Twin Reverbs were 100W in the first part of 1977, then changed to 135W UL in the later part of 1977. The last of the 100W models have components with date codes that are all over the place, sorta like they used up every 100W part they could find before moving on to the 135W models.

I have gut shots of two '77 Pro Reverbs that are 45W models, so I know for certain that they were still being made during part of 1977.

 

[Ten Over]

Here is a schematic for the last of the 45W models:



And a layout:

 

[gridlock]

I believe that my ‘71 Pro Reverb is still 40 watts.

My amp is basically stock except for the BF faceplate and recent servicing.

 

[Dacious]

Fender even in the CBS era built out complete lines. If they had tagboards and transformer sets for the 45 Watters they'd build them out. That's the most expensive part of an amp. You cant afford to toss them out.

Same as car manufacturers often delivered the previous years model ordered even after the new one was announced. It's why 5F1s continued into the BF era! with black tolex long after everything else went blonde and brown.

I had a drip edge blackline 68 VibroChanp with the BF schematic (20 uf first filter with unused stage). The date stamp on the chassis was last week of 68 despite having early SF details. The parts arrived in batches, that's how they built them. It had Aug 66 output, July 67 speaker and Aug 67 power trans. So it's face panel got the stickers ( early ones the workforce left the alignment stickers on by mistake - picked up in first few weeks but too late to change) and lacquer probably a year before the anp chassis was made.

Those large companies didn't do 'just in time' back then. They had pallets of parts that had to be used up. That's why there's lots of '78' Teles that were built up to 83 when the very different Toploader came out. They just kept using up S8 serial number stickers and bits because sales of single coil 'cowboy guitars' tanked in the late 70s.

 

[GeorgiaHonk]

It’s been too long for me to remember many details, but the Pro Reverb I used to own was also a 45-watt version from ‘77. Also tube-rectified. Mine had new Jensen C12Ns and sounded fantastic. But it was LOUD.

 

[jman72]

Here is a schematic for the last of the 45W models:

View attachment 1123971

And a layout:

View attachment 1123972

Thanks for these! I've seen other schematics, but not for the '77 in particular. Here's the back of mine- it's blurry, but you can clearly see the 45 WATT label and the rectifier tube in there. I bought it for $450 about 7 years ago and built a head cab and 2x12 cab for it. I haven't played it a lot in the past couple of years but I pulled it out today and absolutely love it!

 

[jman72]

It’s been too long for me to remember many details, but the Pro Reverb I used to own was also a 45-watt version from ‘77. Also tube-rectified. Mine had new Jensen C12Ns and sounded fantastic. But it was LOUD.

Yep, it is pretty darn loud! And the bass is massive. I wish it had a mid knob on it though- the scooped tone does have a tendency to get lost in my band mix even when the volume is high.

 

[Mexitele Blues]

Just curious...

We have the same amp. I've found that the circuit matches the 74-75 pull boost schematic.

Unfortunately the mid control as found on the Super reverb wouldn't do that much; the resistor in our Pros is equal to about 8 on the knob.

Does your pull-boost work?

 

[FMA]

It’s been too long for me to remember many details, but the Pro Reverb I used to own was also a 45-watt version from ‘77. Also tube-rectified. Mine had new Jensen C12Ns and sounded fantastic. But it was LOUD.

I friend has a early '70s Pro Reverb and it does sound great and although I can't vouch for its output, it can get loud as hell. But it does sound good, very Twin-like.

 

[MuddyWolf]

Here's how you know if your twin is ultra linear. Turn it on and turn it up. If the Windows blow out .....in your neighbors house your amp may be ultra linear.

 

[tele_savales]

may be ultra linear.

"May"

 

[tele_savales]

Here is a schematic for the last of the 45W models:

View attachment 1123971

And a layout:

View attachment 1123972

Nicely done yet again.