I don't agree with leaving 40+ year old electrolytic caps alone. Sure, they might be in spec today, but when their neighbors have failed/gone out of spec, it's just another visit for the customer in the near future. You talk a lot about looks and quality of work, which you do do fine work. Very thoughtful and considerate of the amp/owner every time I've watched. However, It looks lazy(although you thoroughly inspected the parts)when you open the chassis and see partial replacements. I know you thought that when you opened the doghouse in this Pro Reverb.
I’m a little unclear when you refer to “electrolytic caps”. Are you referring to the filter caps or the cathode bypass caps? As you saw in regards to the main filter caps, some were leaking and some still measured OK, but with shameful workmanship. With the IC caps, you know that they will all soon follow. So I replaced them all and did the job right. Amps leave my workshop with my sticker. I would have paid for the IC caps to be replaced if the customer couldn’t see the value in it. Different story with the cathode bypass caps. Unlike a filter cap, I’m sure you know the consequence of a failed bypass cap. Here I was selective, and yes I stand by my policy of only replacing failed or high-ESR bypass caps. Same with the carbon comp resistors. I only needed to change ONE! If they have lasted for 50 years, will they fail next week? Should we change them now because one day they may start to crackle and pop? Where do you stop? Should we replace all the coupling capacitors, too because one day they may leak? I have had vintage amps on my bench where almost every component was replaced. Very sad. I am not secretive about my conservator approach. There are other Techs who will happily bill and swap away. Of course, I am not referring to a touring guitar player who needs his ’64 Super Reverb to perform 100% every night where reliability takes priority over authenticity. Thank you. I’m happy to hear an opposing intelligent thought.
@@theguitaramptech I'm referring to the bypass caps. I do appreciate your approach to conserving vintage amps. I agree with almost everything you do here, almost everything. Like I said, you do excellent work. Thank you for the videos!
@@matthewf1979 As, you know, if a bypass cap fails, it's no biggie. We lose a little gain and the tone will shift. I'm happy to sit with my approach, and respect your well-argued opposing view. 'm happy with even a small agreement. !
I got a Pro Reverb. Picked it up dirt cheap 25+ years ago when they were unfashionable and everyone wanted a Peavey Bandit. Its earlier than yours, as it's only got treble/bass eq on both channels. It sounds awsome. Always did.
I agree. The Pro series is rarely spoken of, but fortunately people like you and I love them. I have a Brownface Pro in the Waiting Room. I'll be sure to video that one for you.
@@theguitaramptech I have been pretty busy and there never seems there's enough time to do personal projects. I hope to finish wiring my recording studio early this year so I can start writing and recording again. Thanks!
Great video as always Chris! I remember a discussion once about what "F&T" stood for. But I'm not sure if there was ever an answer. My guess was Frank & Tom 😂 Merry Christmas from Ohio, US of A.
Hi Bruce! F&T was started by Heinz Fischer and Alfred Tausche in post-WW2 Germany. Thankfully for the music world, their capacitors are still made in Germany. Christmas greetings back at you from 39C (100F) Sydney :)
I get what you're saying, Chris. If I were paying hard cash for a vintage amp, I would be devastated if I opened it up to modern components everywhere. If I wanted modern components, I would buy a Fender reissue rather than an original vintage. I'm am looking forward to part 2 and the sound demo. I haven't heard an ultralinear and I'm very interested to hear if they are HiFi or just cleaner.
That's it, Les!! Most of my clients are not touring pros. They are just as passionate about their gear as many Pros...sometimes more. Pros often view their gear as "tools of the trade". For them it's reliability above all. For the weekend warriors like me, its all about the nuances of tone, and collectability. I think you're going to love the sound sample...not my playing, but the sound of this amp.
It's not about a choice between buying a vintage amp with vintage components vs a modern amp built with modern components; it's a choice between buying an amplifier that was designed to be easily repairable and tweakable, vs a "modern" amp that was pretty much designed to be a throwaway product, difficult and time-consuming to repair because of the low-quality printed-circuit boards, overly complicated "Swiss Army Knife" functions, cost-cutting on critical components (like Fender using the cheapest Illinois caps they can get) and difficulty of accessing the solder-side of the board. People forget that Leo Fender was a radio repair technician first and foremost, and he designed his equipment so that other techs around the country could easily fix it, perhaps even without a schematic to work from, if the amp needed service while a working musician was out on the road. Of course, in this particular case, an amp from January 1979 wasn't built by Leo Fender and he had no involvement in the design process, and it would be a major understatement to say that Fender-CBS went about a lot of things the wrong way. Anyway, as old Fenders go, this is a somewhat less desirable model and era anyway; and so I wouldn't have any problem with changing out old, tired, worn parts as needed to restore the amp to sounding as good, or perhaps even better, than it originally did. People make these kinds of value judgments all the time when restoring vintage cars. It's great to have, say, a 1957 Chevy that was sufficiently well built to be able to drive from coast to coast with power and style, but not unless you change the tires and all the rubber parts and replace all the lubricants and leaky seals and gaskets and so on, not to mention corroded shocks/springs, rotted wiring, crumbling upholstery etc. The vintage car, if not properly rebuilt and refurbished, could blow up catastrophically a half hours drive from your house just as easily as it could on a cross-country trip; and then you'll regret not having done a more thorough job on the restoration. Same thing applies to an amp used at home by a non-professional, it could still blow up in the middle of practice or a rousing jam session, and when one of those components that should have been replaced shorts out and blows up a transformer, then you're left with an expensive, heavy doorstop that has probably lost at least a third if not half of its market value. Better to change the most critical capacitors and any iffy resistors as needed, and give the old parts back to the customer with the amp, than to have the amp blow up simply because somebody wanted to maintain originality for the sake of originality. You can always reinstall the old parts again ---- how many people actually do that, really? ---- but a blown transformer is unlikely to be rewound or replaced with an exact original unless the owner has deep pockets..... and if the owner has deep pockets then he or she certainly could have afforded to get the amp serviced into a reliable long-term condition the first time around.
That’s very well put, good ‘un. I like your car analogy. I view power valves (tubes) and filter caps the same way as tyres and engine oil and I have no problem changing them. When it comes to vintage amps, I always consider a couple of factors: (i) The consequence of a part failure (ii) The intended use of the owner. When it comes to 50yo carbon comp resistors that can drift and can be noisy, should I change them if they are still within 10% and quiet? I won’t. Many will. If they crackle, they're gone. What about coupling caps? If they leak, they’re heading for the bin. Leaking coupling caps may be just noisy, or they can cook power tubes. But, your sound passes through them and different caps DO sound different. I test them and keep the originals wherever possible. How many techs test them or even know HOW to test coupling caps for leakage? If a Cathode bypass cap fails at a gig, most players wouldn’t even notice the slight drop in gain. Once again, I test and replace only those that have failed or failure is imminent (ie high ESR measured at 400Hz). If they have lasted 50 years, they should last till at least the next service I have two 70’s amps on the bench now, both with original filter caps. The MusicMan belongs to a gigging musician. The JMP50 (2204) is tougher decision. He doesn’t gig the amp, and they measure good for ESR and capacitance, even at 45 yo!! I ended up changing both sets of filter caps but for different reasons. The JMP50 is being videoed. I don’t apologise for being a vintage amp conservator, but I always use my judgement and listen to the owner. If he takes the amp on tour and reliability is the name of the game, then that’s what I will give him or her. Let me know what you think after seeing the JMP video in a few weeks time, good ‘un. I enjoy our chats!
I am surprised you didn't change the bypass caps, but I understand your reasoning. I've always taken the view that old electrolytics are probably on the way out so...and I still think that. But I confess I hadn't considered the different (and relatively minor) consequence of a cathode bypass cap failing compared to a power filter. You're right, the consequence is much less serious, so the risk rating is different in a nice old amp that's still mostly original. Cool vid.
You have it in a nutshell, Bladder. Another way to look at it is this. If you were in the market for a 60s or 70s Fender, would you buy the model with all the blue molded caps replaced with Orange Drops? I am confident you wouldn’t. What about if all the carbon comp resistors were all replaced with metal film? Even if I can’t hear the difference, I’d ask myself why some boutique makers still spec carbon comp in certain functions. What about cathode bypass capacitors? If they have lasted 50 years and still measure good capacitance with healthy ESR, are they likely to fail in the next 6 months? (I Can't recall how many I changed in this repair). Even if they ALL failed a week after a service, what would be the consequence at a gig? The sad truth is many Techs are uneducated in electronics. We have no governing body. Sadly, Harley, my German Shepherd, could legally hang an “Amp Tech” sign on his kennel. For example, many Techs can’t explain what is ESR, how to measure it, at what frequency to measure it and even at what frequency their cheap ESR meter operates (assuming they even own one). The cheapies often measure at 100KHz, an irrelevant frequency for our audio gear. I am pretty confident you would opt for the most original amp, Bladder. And this is the service I offer my clients. If you are a Pro player and about to start a nation-wide tour, my priorities shift from originality to reliability, and the owner chooses where on that spectrum I land. I have such clients, and I easily make such changes to my approach. On the other side of the coin, if ALL the filter capacitors are changed with good quality capacitors and having pride in their workmanship, would you value that? I sure would. I love hearing from you. Don't let that change just because we differ on a point of view.
@@theguitaramptech , its why we own dogs ---- they don't judge us for such things as red toenails. But if you don't give them a good daily walk and feed them enough dog treats, and maybe share a scrap of your dinner, you get The Stare, or the Sad Downturned Eyes......
I agree 100% Good 'Un. I firmly believe there are only two forms of "unconditional love". (i) The love a parent has for its child. (ii) The love a dog has for its pack leader (us).
Are you sure the 100k balance resistors are not mounted in the chassis , right up at the side ? I’m currently working on a 1978 135w, that’s where they are mounted on it . Trev
That was the common misplaced criticism of UltraLinear. A lot depends on where the screen taps were taken on the primary side of the OT compared to the Plates. Obviously, if the taps are taken at the same place as the plates, we have a non-linear triode connection. As the tap is moved further away, the non-linearity is straightened out as we approach the B+ connection. From memory, the most linear, or UltraLinear is at a 40% tap. The Fender Ultra Linear's were nowhere near these levels. It was an invalid criticism of these amps. Yes, they are cleaner, but certainly not, HiFi clean. Wait for Part Two Ian...its gorgeous.
I don't agree with leaving 40+ year old electrolytic caps alone. Sure, they might be in spec today, but when their neighbors have failed/gone out of spec, it's just another visit for the customer in the near future.
You talk a lot about looks and quality of work, which you do do fine work. Very thoughtful and considerate of the amp/owner every time I've watched. However, It looks lazy(although you thoroughly inspected the parts)when you open the chassis and see partial replacements. I know you thought that when you opened the doghouse in this Pro Reverb.
I’m a little unclear when you refer to “electrolytic caps”. Are you referring to the filter caps or the cathode bypass caps? As you saw in regards to the main filter caps, some were leaking and some still measured OK, but with shameful workmanship. With the IC caps, you know that they will all soon follow. So I replaced them all and did the job right. Amps leave my workshop with my sticker. I would have paid for the IC caps to be replaced if the customer couldn’t see the value in it.
Different story with the cathode bypass caps. Unlike a filter cap, I’m sure you know the consequence of a failed bypass cap. Here I was selective, and yes I stand by my policy of only replacing failed or high-ESR bypass caps. Same with the carbon comp resistors. I only needed to change ONE! If they have lasted for 50 years, will they fail next week? Should we change them now because one day they may start to crackle and pop? Where do you stop? Should we replace all the coupling capacitors, too because one day they may leak? I have had vintage amps on my bench where almost every component was replaced. Very sad.
I am not secretive about my conservator approach. There are other Techs who will happily bill and swap away.
Of course, I am not referring to a touring guitar player who needs his ’64 Super Reverb to perform 100% every night where reliability takes priority over authenticity.
Thank you. I’m happy to hear an opposing intelligent thought.
@@theguitaramptech I'm referring to the bypass caps. I do appreciate your approach to conserving vintage amps. I agree with almost everything you do here, almost everything.
Like I said, you do excellent work.
Thank you for the videos!
@@matthewf1979 As, you know, if a bypass cap fails, it's no biggie. We lose a little gain and the tone will shift. I'm happy to sit with my approach, and respect your well-argued opposing view. 'm happy with even a small agreement. !
I got a Pro Reverb. Picked it up dirt cheap 25+ years ago when they were unfashionable and everyone wanted a Peavey Bandit. Its earlier than yours, as it's only got treble/bass eq on both channels. It sounds awsome. Always did.
I agree. The Pro series is rarely spoken of, but fortunately people like you and I love them. I have a Brownface Pro in the Waiting Room. I'll be sure to video that one for you.
I once owned a pro reverb back in the early 80, It was a 70's model not sure what year that had Jenson speakers, this was in the UK
Very nice, Sparky.
Always interesting to watch your videos Chris. I hope all is well down under. All is good up over, near NYC...
Phil
And its always great to hear from you, Phil. This year looks like its going to be a good one. You?
@@theguitaramptech I have been pretty busy and there never seems there's enough time to do personal projects. I hope to finish wiring my recording studio early this year so I can start writing and recording again. Thanks!
Great video as always Chris! I remember a discussion once about what "F&T" stood for. But I'm not sure if there was ever an answer. My guess was Frank & Tom 😂 Merry Christmas from Ohio, US of A.
Hi Bruce! F&T was started by Heinz Fischer and Alfred Tausche in post-WW2 Germany. Thankfully for the music world, their capacitors are still made in Germany.
Christmas greetings back at you from 39C (100F) Sydney :)
@theguitaramptech Awesome, thanks for the info!! 👍 A warm 55F in Ohio! Probably means snow storm coming!
Hi Master. Good job Always !
Good to hear from you Miguel. Have a great Christmas.
@@theguitaramptech Thank's a lot Master. Merry Christmas.
Hi Chris, fab video, just so much info and repair instruction..Just a treat to watch..Thanks for posting..Ed..UK..😄
Thank you, Ed. I've enjoyed your online presence this year. From a steaming hot Sydney to a (probably) cold and cloudy UK, have a wonderful 2024.
I get what you're saying, Chris. If I were paying hard cash for a vintage amp, I would be devastated if I opened it up to modern components everywhere. If I wanted modern components, I would buy a Fender reissue rather than an original vintage. I'm am looking forward to part 2 and the sound demo. I haven't heard an ultralinear and I'm very interested to hear if they are HiFi or just cleaner.
That's it, Les!! Most of my clients are not touring pros. They are just as passionate about their gear as many Pros...sometimes more. Pros often view their gear as "tools of the trade". For them it's reliability above all. For the weekend warriors like me, its all about the nuances of tone, and collectability.
I think you're going to love the sound sample...not my playing, but the sound of this amp.
It's not about a choice between buying a vintage amp with vintage components vs a modern amp built with modern components; it's a choice between buying an amplifier that was designed to be easily repairable and tweakable, vs a "modern" amp that was pretty much designed to be a throwaway product, difficult and time-consuming to repair because of the low-quality printed-circuit boards, overly complicated "Swiss Army Knife" functions, cost-cutting on critical components (like Fender using the cheapest Illinois caps they can get) and difficulty of accessing the solder-side of the board.
People forget that Leo Fender was a radio repair technician first and foremost, and he designed his equipment so that other techs around the country could easily fix it, perhaps even without a schematic to work from, if the amp needed service while a working musician was out on the road. Of course, in this particular case, an amp from January 1979 wasn't built by Leo Fender and he had no involvement in the design process, and it would be a major understatement to say that Fender-CBS went about a lot of things the wrong way.
Anyway, as old Fenders go, this is a somewhat less desirable model and era anyway; and so I wouldn't have any problem with changing out old, tired, worn parts as needed to restore the amp to sounding as good, or perhaps even better, than it originally did. People make these kinds of value judgments all the time when restoring vintage cars. It's great to have, say, a 1957 Chevy that was sufficiently well built to be able to drive from coast to coast with power and style, but not unless you change the tires and all the rubber parts and replace all the lubricants and leaky seals and gaskets and so on, not to mention corroded shocks/springs, rotted wiring, crumbling upholstery etc. The vintage car, if not properly rebuilt and refurbished, could blow up catastrophically a half hours drive from your house just as easily as it could on a cross-country trip; and then you'll regret not having done a more thorough job on the restoration. Same thing applies to an amp used at home by a non-professional, it could still blow up in the middle of practice or a rousing jam session, and when one of those components that should have been replaced shorts out and blows up a transformer, then you're left with an expensive, heavy doorstop that has probably lost at least a third if not half of its market value. Better to change the most critical capacitors and any iffy resistors as needed, and give the old parts back to the customer with the amp, than to have the amp blow up simply because somebody wanted to maintain originality for the sake of originality. You can always reinstall the old parts again ---- how many people actually do that, really? ---- but a blown transformer is unlikely to be rewound or replaced with an exact original unless the owner has deep pockets..... and if the owner has deep pockets then he or she certainly could have afforded to get the amp serviced into a reliable long-term condition the first time around.
That’s very well put, good ‘un. I like your car analogy. I view power valves (tubes) and filter caps the same way as tyres and engine oil and I have no problem changing them. When it comes to vintage amps, I always consider a couple of factors: (i) The consequence of a part failure (ii) The intended use of the owner.
When it comes to 50yo carbon comp resistors that can drift and can be noisy, should I change them if they are still within 10% and quiet? I won’t. Many will. If they crackle, they're gone.
What about coupling caps? If they leak, they’re heading for the bin. Leaking coupling caps may be just noisy, or they can cook power tubes. But, your sound passes through them and different caps DO sound different. I test them and keep the originals wherever possible. How many techs test them or even know HOW to test coupling caps for leakage?
If a Cathode bypass cap fails at a gig, most players wouldn’t even notice the slight drop in gain. Once again, I test and replace only those that have failed or failure is imminent (ie high ESR measured at 400Hz). If they have lasted 50 years, they should last till at least the next service
I have two 70’s amps on the bench now, both with original filter caps. The MusicMan belongs to a gigging musician. The JMP50 (2204) is tougher decision. He doesn’t gig the amp, and they measure good for ESR and capacitance, even at 45 yo!! I ended up changing both sets of filter caps but for different reasons. The JMP50 is being videoed.
I don’t apologise for being a vintage amp conservator, but I always use my judgement and listen to the owner. If he takes the amp on tour and reliability is the name of the game, then that’s what I will give him or her. Let me know what you think after seeing the JMP video in a few weeks time, good ‘un. I enjoy our chats!
I am surprised you didn't change the bypass caps, but I understand your reasoning. I've always taken the view that old electrolytics are probably on the way out so...and I still think that. But I confess I hadn't considered the different (and relatively minor) consequence of a cathode bypass cap failing compared to a power filter. You're right, the consequence is much less serious, so the risk rating is different in a nice old amp that's still mostly original.
Cool vid.
You have it in a nutshell, Bladder. Another way to look at it is this. If you were in the market for a 60s or 70s Fender, would you buy the model with all the blue molded caps replaced with Orange Drops? I am confident you wouldn’t. What about if all the carbon comp resistors were all replaced with metal film? Even if I can’t hear the difference, I’d ask myself why some boutique makers still spec carbon comp in certain functions. What about cathode bypass capacitors? If they have lasted 50 years and still measure good capacitance with healthy ESR, are they likely to fail in the next 6 months? (I Can't recall how many I changed in this repair). Even if they ALL failed a week after a service, what would be the consequence at a gig?
The sad truth is many Techs are uneducated in electronics. We have no governing body. Sadly, Harley, my German Shepherd, could legally hang an “Amp Tech” sign on his kennel. For example, many Techs can’t explain what is ESR, how to measure it, at what frequency to measure it and even at what frequency their cheap ESR meter operates (assuming they even own one). The cheapies often measure at 100KHz, an irrelevant frequency for our audio gear.
I am pretty confident you would opt for the most original amp, Bladder. And this is the service I offer my clients. If you are a Pro player and about to start a nation-wide tour, my priorities shift from originality to reliability, and the owner chooses where on that spectrum I land. I have such clients, and I easily make such changes to my approach.
On the other side of the coin, if ALL the filter capacitors are changed with good quality capacitors and having pride in their workmanship, would you value that? I sure would.
I love hearing from you. Don't let that change just because we differ on a point of view.
Tell the truth, Chris: you reserve that red nail polish for your toenails! 😁
It was once, OK. I was young and experimenting! In my autumn years, red is strictly fingernails!
@@theguitaramptech , its why we own dogs ---- they don't judge us for such things as red toenails. But if you don't give them a good daily walk and feed them enough dog treats, and maybe share a scrap of your dinner, you get The Stare, or the Sad Downturned Eyes......
I agree 100% Good 'Un. I firmly believe there are only two forms of "unconditional love". (i) The love a parent has for its child. (ii) The love a dog has for its pack leader (us).
Are you sure the 100k balance resistors are not mounted in the chassis , right up at the side ?
I’m currently working on a 1978 135w, that’s where they are mounted on it .
Trev
You might be right, Trev.
Ultra Linear sounds like a HIFI thing
That was the common misplaced criticism of UltraLinear. A lot depends on where the screen taps were taken on the primary side of the OT compared to the Plates. Obviously, if the taps are taken at the same place as the plates, we have a non-linear triode connection. As the tap is moved further away, the non-linearity is straightened out as we approach the B+ connection. From memory, the most linear, or UltraLinear is at a 40% tap. The Fender Ultra Linear's were nowhere near these levels. It was an invalid criticism of these amps. Yes, they are cleaner, but certainly not, HiFi clean. Wait for Part Two Ian...its gorgeous.
Fantastic most hifi is 40%