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Recently, a (supposed) 1967 Pro Reverb Blackface came on sale locally.

I'm told that the speakers are "the original Utahs".

Can this be right? How long do speakers in guitar amps last?

Similarly, the circuit board photo shows a bunch of electronic components, point to point wired. How long do these last?

Broadly, is an old guitar amp a "good thing", or actually a liability, from a playing perspective (ignoring collectability etc)?

  • To my knowledge: Old Fender amplifiers have old components and overtime they tend to run electrically hot as time goes on. This leads to electrical components over heating and just causes are real mess. In fact I know blackface owners who needed to re-valve twice a year because they didn't spend the hundreds it takes to fine tune them. It's rare that you come across an original Blackface/Silverface that doesn't need calibration. user37496 made a great point in his answer "It's not necessarily that older is better." Technology progresses, there's killer stuff available now days, make use of it. – jazzboy Oct 31 '17 at 10:56
  • I'm not sure what a "Utah" is, but the Pro Reverb is most likely to have come with Jensen or Oxford speakers. See: fenderguru.com/amps/pro-reverb Looks like the wiring is point to point, which is a good thing: goo.gl/images/DBy5zC – Todd Wilcox Oct 31 '17 at 11:47
  • If you look around the webs, you can find an awful lot of digital processors that have settings to recreate the tonality (basically amplitude vs. frequency of overtones and resonances) of almost any analog amp. – Carl Witthoft Oct 31 '17 at 15:18
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    @CarlWitthoft If you play any of those digital processors, you'll quickly realize the difference between marketing claims and actual reality. I've yet to use any digital device (amp, effect, synth, etc.) that sounds and feels like its analog counterpart, and I've tried a lot of them. Even when you're not playing an actual digital item it's different. Mixing and recording digital modeling amps is a unique challenge. For some reason they just don't sit right - or at least they are so different that I haven't figured out how to mix them. – Todd Wilcox Oct 31 '17 at 20:08
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    @CarlWitthoft If you're content to play modeling amps and digital soft synths, then play them. I continue to be amazed by the sensitivity of human hearing, even as my hearing declines with age. And I'm in good company. We could all be fooling ourselves, but it seems unlikely that we all are. I don't claim to have golden ears at all. – Todd Wilcox Nov 1 '17 at 12:39
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Though it may not be want you want to hear the answer is "until you break them".

On vintage Fenders like that it's hit or miss whether they have original speakers. More often than not, a well used amp that old usually ends up getting speaker(s) replaced at some point. But there's no reason why it couldn't have the original speakers if it was well taken care of.

Broadly, is an old guitar amp a "good thing", or actually a liability, from a playing perspective (ignoring collectability etc)?

For the sound that all depends on your taste. If you want a vintage Fender sound then yes it's definitely worth considering a vintage Fender amp. Modern Fenders or boutiques might get you close but if you know you want a certain sound it's always easiest to go straight to the source.

It's not necessarily that older is better. It's that many people are chasing the tone(s) of that era so it makes sense to use the amps that were used then.

But, yes, they are definitely a maintenance liability relative to modern amps. You'd probably want a reputable tech to take a look and do some maintenance especially if you have to rely on it for gigs or something.

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Concerns for an amp such as the one you describe:

  • Capacitors, as Tetsujin mentions. Unless the amp has been powered off for most of its life, I'd be surprised if it has all original caps. If it does, then it's more likely to have a catastrophic cap failure where a cap literally blows its top and sprays oil over the insides of the chassis. For what to look for in capacitors, see: http://paulrepair.com/blog/blog/2009/03/12/blown-capacitors-it-is-a-plague/
  • Speaker surrounds. Depending on the construction (if made from foam rubber), the surrounds may have dry rotted. A visual check of the speaker (or a picture) will tell you if the surround is intact. Look around the rim of the speaker for gaps in the surround. Note: after a few web searches it looks like guitar amp speakers may not use foam rubber surrounds, so this may not be a problem with guitar amps at all. It is a problem with hi-fi speakers from the 70s and later.
  • Power cable type. Old amps like these were often built with a two-prong power cable and perhaps a switch that selects how it is grounded. While the amp has likely not killed anyone yet, when buying such an amp I strongly suggest allocating a bit of extra money to have the power cable modified so that it is a three-prong cable with the safety ground wired to chassis.

Is an old guitar amp a good thing? In some ways:

  • Sounds like the amp in question may be point-to-point wired with discrete components, rather than having components soldered to a PCB. Not only does this construction type often sound very slightly better (after playing the Moog reissue Model D and comparing to the Voyager, I myself believe in PtP discrete sounding better), but it also lasts longer. Surface-mounted components on a PCB are more prone to damage and are harder to fix.
  • Other components, particularly the output transformer, may have been over-engineered and may sound better and last longer. These days, the musical instrument market is very tight with much smaller margins, so the bare minimum acceptable component is often used, except in boutique designs. There is a company in Los Angeles that makes their money by taking reissues by companies like Fender and Marshall and replacing things like caps and output transformers with components that have the original spec, so it's more true to the original amp.
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As a separate point; at that age the valves will probably have been replaced many times, but I bet no-one ever thought to replace the capacitors.

A friend of mine had a Vibralux of similar age. Replacing the valves didn't improve the sound to the standard we expected, so he spoke the the "engineers at work". Fortunately, "work" was the BBC, where they have a lot of people still who know their stuff.
His first comment was 'When were the capacitors last changed?'
After a short conversation it was discovered that the BBC, at least back in the old analog days, would schedule a complete change of all capacitors on all equipment every 5 years.

We were really uncertain how it would go to replace the big old 'brown toffee' capacitors with new shiny blue ones... but we went ahead & changed the power section first just to see.

It was like having a new amp.

Lesson learned: Never doubt an old brown-coat boffin who's worked at the BBC for 40 years ;)

  • The BBC engineers certainly know their stuff, but in the Beeb used to go way over the top in over-specifying and over-maintaining their electronics. Actually, the average life of electrolytic capacitors (the cylindrical can shaped ones) has probably decreased over time, not increased. Getting 5 years life out of a new one is pretty good. Failing caps are the most common reason why modern computer monitors etc "die". But the old "brown" paper-and-wax small capacitors stopped being "standard parts" 50 years ago - modern replacements are much better and should last for ever. – user19146 Oct 31 '17 at 10:10
  • The Beeb used to be run like a civil service department - nothing was over the top, not even their +6 nominal levels, when the rest of the world was quite happy with +4 ;) I agree 5 years is a bit aggressive, but the amp was over 40 years old at the time. – Tetsujin Oct 31 '17 at 10:14
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    If you do replace the caps, don't waste your money on "hi fi audio grade" parts that cost 50 dollars each - just stick to standard parts that cost 50 cents. Hi fi grade components are just to give people bragging rights about having the most expensive amp ever built - they won't make any noticeable difference to the sound! – user19146 Oct 31 '17 at 10:17
  • True - never even thought about that, wouldn't dream of it myself ;) – Tetsujin Oct 31 '17 at 10:33
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It's going to be very dependent on several things. How much use the amp has had, either being played through, or thrown in and out of Transit vans. Where it's been stored: damp basements or attics are its worst enemies.

Components will degrade with age, and speakers will suffer if the atmosphere is damp - as will any other electronic parts. The valves can easily be changed - and should be - but valve seats deteriorate, become brittle, and cause microphony. I remember changing them on 15 yr old amps from the '50s/'60s.

Soldered joints are infamous for 'drying out', but with a bit of fettling with a soldering iron will be good for many more years. PCBs crack, especially when an amp is dropped, and that, while not insurmountable, could be the cause of death to an old amp. Capacitors start to leak, so don't hold charge any more. Point to point is far better.

So, the answer is more no than yes, but most components can be replaced, with very similar sounds being available, or maybe even better ones! Judging by the amount of old Fenders around, others seem to agree!

So,

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    Note, it sounds like this amp does not have a PCB at all. – Todd Wilcox Oct 31 '17 at 11:30

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