True.
I would recommend a used variac. New ones are pretty dear.
A Chinese one can be okay. I'll say this. You can get anything, from terrible quality to top line stuff made in China. We used to joke about "Jap cra p", we don't joke anymore. China has the top two speaker manufacturing plants in the world right now. If they put the effort into a top flight semi fab and made parts under license, I bet they would be as good as any other.
What's worse than a Philips incandescent lamp? Not much.
All I will say is that Wall Street did this for us. No way would a real business person have shut down US factories, that takes an accountant. In other words, we did it to ourselves.
I would recommend a used variac. New ones are pretty dear.
A Chinese one can be okay. I'll say this. You can get anything, from terrible quality to top line stuff made in China. We used to joke about "Jap cra p", we don't joke anymore. China has the top two speaker manufacturing plants in the world right now. If they put the effort into a top flight semi fab and made parts under license, I bet they would be as good as any other.
What's worse than a Philips incandescent lamp? Not much.
All I will say is that Wall Street did this for us. No way would a real business person have shut down US factories, that takes an accountant. In other words, we did it to ourselves.
Nothing is worse than a Philips light bulb. Why is the sky blue? Because Philips isn’t worth a $$$$. Why does the sun come up in the morning? Because Philips isn’t worth a $$$$. Why does my, well, organ, get hard when I look at a woman? You get the idea. It’s the explanation for everything.
It’s easy to boycott Philips. Not so easy to boycott an entire nation when our economies are too intertwined to undo. Unless you wall yourself off on a subsistence farm somewhere. Even then your investments are probably feeding the beast, at least indirectly. Unless you hide your cash under a mattress. Eventually that old Adcom is going to need new caps in the power supply. You either get them from China or take your chances with NOS surplus soup cans that have been in a warehouse for 20+ years. They might have been USA made - it would say so right on them.
More and more listings of our regular trusted parts from Mouser now come with the warning “Tariff may be applied if shipped to the United States”. Ones that didn’t, even when all the tariffing did start up years back. Like 2N3904’s and Fairchild C5200’s. That means they ain’t being made in Korea or Mexico anymore. The TO-3’s are some of the last holdouts - and how many are left? You can count them on one hand.
It’s easy to boycott Philips. Not so easy to boycott an entire nation when our economies are too intertwined to undo. Unless you wall yourself off on a subsistence farm somewhere. Even then your investments are probably feeding the beast, at least indirectly. Unless you hide your cash under a mattress. Eventually that old Adcom is going to need new caps in the power supply. You either get them from China or take your chances with NOS surplus soup cans that have been in a warehouse for 20+ years. They might have been USA made - it would say so right on them.
More and more listings of our regular trusted parts from Mouser now come with the warning “Tariff may be applied if shipped to the United States”. Ones that didn’t, even when all the tariffing did start up years back. Like 2N3904’s and Fairchild C5200’s. That means they ain’t being made in Korea or Mexico anymore. The TO-3’s are some of the last holdouts - and how many are left? You can count them on one hand.
I agree. Completely true on every count.
Now what have I been saying for years? We voted with our dollars. Our business communities for decades have been chasing the dollar to save pennies, no matter the long term cost. Accountants who can't see long term. They killed us all for a few bucks right now, got their bonuses and retired all at the expensive of our collective future. We saw it early in Canada as US firms bought Canadian companies, shut them down and moved manufacturing to the 'States. Those same people then moved manufacturing to Mexico and other countries. Don't be upset with China! We gave them our future, "we" are the people who are proud Americans.
I'm not being political at all, not trying to start a fight. Just look at the history of business and place the blame where it belongs. As a Canadian with open eyes, I watched it happen over the decades. It began with shareholders and the shift to keep them happy at almost any cost. As a group, people are both greedy and stupid. No idea of long term effects.
You tell me ... is it too late, or not? What will it take to reverse the damage?
Now what have I been saying for years? We voted with our dollars. Our business communities for decades have been chasing the dollar to save pennies, no matter the long term cost. Accountants who can't see long term. They killed us all for a few bucks right now, got their bonuses and retired all at the expensive of our collective future. We saw it early in Canada as US firms bought Canadian companies, shut them down and moved manufacturing to the 'States. Those same people then moved manufacturing to Mexico and other countries. Don't be upset with China! We gave them our future, "we" are the people who are proud Americans.
I'm not being political at all, not trying to start a fight. Just look at the history of business and place the blame where it belongs. As a Canadian with open eyes, I watched it happen over the decades. It began with shareholders and the shift to keep them happy at almost any cost. As a group, people are both greedy and stupid. No idea of long term effects.
You tell me ... is it too late, or not? What will it take to reverse the damage?
I’m not sure that can be answered without getting political.
People do not need amplifiers. They’re one of the first things would that have to go. I’m going to shut up on this now. When I do get back into building amps in another year or two (reasons unrelated to anything going on in the world), I’ll get out my 25 year old Made in China variac and pick up where things left off.
People do not need amplifiers. They’re one of the first things would that have to go. I’m going to shut up on this now. When I do get back into building amps in another year or two (reasons unrelated to anything going on in the world), I’ll get out my 25 year old Made in China variac and pick up where things left off.
If I want 50 w music peaks, I repair an old amp headed to the scrap heap. Amp for "parts or repair" off ebay. I listen to music 14 hours a day sometimes, one of the benefits of retirement. I put up with a 2" speaker in a table radio when employed, but I can now have 54-17000 hz with low distortion. SP2 used off ebay made in MS. Same with a mixer I sing & play autoharp through, I repaired for $20 instead of a $99 new one. The 16 vac wall transformer for the mixer from triad was from ***** but cost << than a new mixer. The room heater element I use for amp protection came from somebody's trash. I did not cause it to be imported. I have found e-caps from nichicon, rubicon, panasonic, kemet, usually come from countries I find to be benign trade partners. I had a stash of phillipine fairchild semis, thai or malay resistors, Mex On TO3's, 2 DVM's, that my local unemployed house painter hauled to the steel scrapyard for me in 2020. Even if I buy components from the offensive source, or the inevitable DVM, it costs less than a new class D amp designed to fail in 6 years. I have found new speaker drivers assembled 60 miles from here, admittedly from global components. When I finish I get beautiful music, in 3 different residences. I'm not as productive as a pro tech, but I do not need $3000 in squeaky new tools to make a class AB amp or a mixer work reliably. Same with my 4 organs, 3 hammond tonewheels, one schober filtered triangle waves.
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No you don't. But you do need the instrumentation to make amps work correctly. Sorry, no way around this.
I get stuff in weekly, several. These from techs without the required equipment. Almost every piece does not meet spec. Some blew up. I wouldn't spend money on stuff I don't need, and I know enough to know what I do need and why.
The source or value of a piece does not exclude it from the need to be repaired properly. There is never an excuse, sorry. You could get away with a lot with old tube equipment (not modern tube equipment), but solid state equipment absolutely does require that you set it up properly. I recently repaired a Sylvania radio/phono that used germanium outputs. It blew up because the previous "tech" didn't repair it even close to properly. They used ECG parts on top of that. They got paid, the customer had to ship it up from the 'States to have me repair it in Canada, then back to him(paying for the same service twice). The previous person was said to be good. Well, guess what? Nope and he cost the customer a lot of money. Is that fair? That repair person is convinced they are great, and they don't need good equipment. Total delusion. Experience will only get you so far, and if you really are experienced you know what you need, and you have it.
I get stuff in weekly, several. These from techs without the required equipment. Almost every piece does not meet spec. Some blew up. I wouldn't spend money on stuff I don't need, and I know enough to know what I do need and why.
The source or value of a piece does not exclude it from the need to be repaired properly. There is never an excuse, sorry. You could get away with a lot with old tube equipment (not modern tube equipment), but solid state equipment absolutely does require that you set it up properly. I recently repaired a Sylvania radio/phono that used germanium outputs. It blew up because the previous "tech" didn't repair it even close to properly. They used ECG parts on top of that. They got paid, the customer had to ship it up from the 'States to have me repair it in Canada, then back to him(paying for the same service twice). The previous person was said to be good. Well, guess what? Nope and he cost the customer a lot of money. Is that fair? That repair person is convinced they are great, and they don't need good equipment. Total delusion. Experience will only get you so far, and if you really are experienced you know what you need, and you have it.
Funny, I consider high fidelity music from a repaired amp for 14 hours a day for 6 or 8 years to be a suitable life test. No, I don't run max power for that time. Only for an hour into load resistors. I don't want to listen to that much sound. Ultrasonic oscillation can be detected with an analog DVM a 390 pf cap, and a selenium bridge rectifier. Simpson 266 had such a rectifier. I had and repaired two such oscillation problems. BTW I won't touch germanium amps. My employer considered germanium a waste of time in 1975. They kept using GE & RCA vacuum tubes to drive solenoid valves 2-50 hz until after I left in 1978. There were some Delco flying saucer germaniums on the junk shelf, but not in the trucks out searching for oil.
NTE semiconductors were all that was available to people that did not have a tax number in 1985. Some of them were actually good. Many were ****. All of them had most of the specifications left off the datasheet that the mainline parts had.
NTE semiconductors were all that was available to people that did not have a tax number in 1985. Some of them were actually good. Many were ****. All of them had most of the specifications left off the datasheet that the mainline parts had.
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How do you know it is performing to spec? You don't. So how can you call it "high fidelity"? As a life test, if the equipment is never pushed, maybe it isn't going to perform to spec. No one knows. If you are happy with it, cool. That is an entirely different question.
Decades of experience with techs all over the world prove that if you don't have the equipment you need, what you "fix" isn't guaranteed to work properly and often doesn't. In fact, without the equipment there is a ton of stuff you are not aware of.
Electronics can be impressively resilient. I got an amplifier in, all four output devices a different case style. It lasted a year and finally blew up, the idiot that repaired it ran a repair business! Most of the outputs were not rated for the voltage and power required, why it didn't fail immediately is beyond me.
You have no idea how much I get in that has high distortion but the previous tech claims they can hear distortion and do not need a meter. Several amps measured well over 1 % THD (you could hear it). A few didn't even work properly as other parts were bad they didn't clue into. There is a very good reason why you needed some basic equipment before you could be authorized to do warranty service. A THD meter was part of that basic equipment list, and a low distortion oscillator along with industry standard dummy loads. This isn't for bragging rights, you need this stuff, period.
You do what you want. But do not encourage people to believe they don't need the basic equipment, because you are wrong. Do you need an AP? Probably not, most don't. But you do need SOMETHING! How good depends on what you're doing.
Decades of experience with techs all over the world prove that if you don't have the equipment you need, what you "fix" isn't guaranteed to work properly and often doesn't. In fact, without the equipment there is a ton of stuff you are not aware of.
Electronics can be impressively resilient. I got an amplifier in, all four output devices a different case style. It lasted a year and finally blew up, the idiot that repaired it ran a repair business! Most of the outputs were not rated for the voltage and power required, why it didn't fail immediately is beyond me.
You have no idea how much I get in that has high distortion but the previous tech claims they can hear distortion and do not need a meter. Several amps measured well over 1 % THD (you could hear it). A few didn't even work properly as other parts were bad they didn't clue into. There is a very good reason why you needed some basic equipment before you could be authorized to do warranty service. A THD meter was part of that basic equipment list, and a low distortion oscillator along with industry standard dummy loads. This isn't for bragging rights, you need this stuff, period.
You do what you want. But do not encourage people to believe they don't need the basic equipment, because you are wrong. Do you need an AP? Probably not, most don't. But you do need SOMETHING! How good depends on what you're doing.
I am a musician with 9 years amateur training. I have ears still capable of 14 khz. When the distortion is low enough, I can hear the difference between a Steinway grand, a Bosendorfer grand, and a Yamaha baby grand or console, on properly made recordings. My 1 % HD dynaco ST70 did not reproduce to such accuracy. My repaired Peavey M-2600, CS800s, and the stolen PV-4c amps, do reproduce such accuracy through the very pleasing SP2s(2004). I have a Steinway console piano sitting in the same room as the SP2 speakers. If I can make the amp & speaker sound like the piano, I am done. Yes, the actual 11' grands have better bass than my console piano. I can hear that too.
Test tracks are Peter Nero "Young & Warm & Beautiful", and tinkly bells and percussion on Martin Denny Hawaii.
I do not sell my services. I donate them in some cases.
Having pro equipment makes you productive, but scares off many newbies that could make significant progress with a DVM, an analog VOM, some test leads, a FM radio, load resistors, a light bulb box, and some good speakers. All that good equipment going to the dump, to be replaced by new Class D trash lasting only a few years.
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Actually, no. That doesn't cut it. Wishful thinking.
I work in recording studios, did live production. On and on. Human beings are terrible test instruments. I work with musicians, studio techs and so forth. Proved time and time again that your hearing is very poor at picking up distortion. Your best bet is a constant tone. Still not good enough. With music you can only hear some defects and gross distortion.
Yes, you can find some faults and "wing it". But you can only get something repaired and in spec by pure luck without the training and equipment required.
You wouldn't believe what some folks think sounds okay. Then you fix it and they realise they can't tell from listening. By fix it, I mean properly adjusted and performing better than spec. The specifications are for the worst performing piece off the line under non-ideal conditions.
Whether your give your services away at no charge or not is completely immaterial. The only thing that matters is that equipment you touch does in fact work properly and is performing in spec. when you are done. Without the very basic equipment, materials and training, you haven't a clue. Just wishful thinking. I haven't even addressed the fact that some test equipment drifts out of tolerance and you have to ensure that is operating in spec. Also, many meters are not capable of reading millivolts accurately enough to set bias currents. You cannot see better than gross distortion on an oscilloscope, try determining 1% on a scope. You'll fail.
Anyway, this is off-topic and pointless. If you want to stick your head in the sand, go ahead. The entire service industry disagrees with your stance, again for very good reason.
I work in recording studios, did live production. On and on. Human beings are terrible test instruments. I work with musicians, studio techs and so forth. Proved time and time again that your hearing is very poor at picking up distortion. Your best bet is a constant tone. Still not good enough. With music you can only hear some defects and gross distortion.
Yes, you can find some faults and "wing it". But you can only get something repaired and in spec by pure luck without the training and equipment required.
You wouldn't believe what some folks think sounds okay. Then you fix it and they realise they can't tell from listening. By fix it, I mean properly adjusted and performing better than spec. The specifications are for the worst performing piece off the line under non-ideal conditions.
Whether your give your services away at no charge or not is completely immaterial. The only thing that matters is that equipment you touch does in fact work properly and is performing in spec. when you are done. Without the very basic equipment, materials and training, you haven't a clue. Just wishful thinking. I haven't even addressed the fact that some test equipment drifts out of tolerance and you have to ensure that is operating in spec. Also, many meters are not capable of reading millivolts accurately enough to set bias currents. You cannot see better than gross distortion on an oscilloscope, try determining 1% on a scope. You'll fail.
Anyway, this is off-topic and pointless. If you want to stick your head in the sand, go ahead. The entire service industry disagrees with your stance, again for very good reason.
Ha Ha Ha Ha Ha. Constant tone blah! Studios record pop, rock, reggae, rap "music". Guitars produce almost no frequencies over 7000 hz. Most pop band musicians ruin their hearing in their teens with the "turn it up to 11" syndrome. The last pop bands I've seen use a wood piano was Kid Rock at Graceland 15 years ago, and Munford & Son & Lady Gaga on SNL 50 concert last week. Lady Gaga & Diane Krall never donate their time to PBS where I would hear them. The rest of pop acts use electronic toys for keys. About as expressive as a city garbage truck. You want difficult to reproduce music, it is recorded in a hall with ambience. Includes instruments that go up to 20000 hz. Not in some studio.
Ever hear of a 16000 hz + 20000 hz IM distortion test? Bad results approximate the artifacts I hear on top octave steinway, brush cymbal and tinkly bell tracks with 1% HD amps.
See PA thread for what Conanski says about some other sound men he meets.
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They record more than rock ... I did live sound as in Symphony Orchestras and live stage as well. Also television audio mix / production. This is all stuff that you get as a consumer across all media.
It doesn't matter, there is a lot above 7KHz and you're showing your total lack of knowledge. The basic point is, humans are not test instruments and have been proved incorrect time and time again over what low distortion is.
You do not have any reference at all. You haven't any clue as to what amounts of distortion you can detect and are confusing it with frequency response. If you want to argue how good the most adept human is at detecting distortion, then you better get ready to swallow all your pride and admit defeat. It isn't my job to educate any one person, I was educated and I suggest you take the journey. This is a waste of everyone's time who has figured out how poorly humans assess distortion.
Humans compare pretty well. We can sort out over time a good system from a less good system. Almost every single day I perform THD tests and my IMD tests are 19 KHz and 20 KHz. Most of us have a complete understanding of what these tests show and sound like. Your IMD test is going to show difference at 4 KHz, the standard is a 1 KHz unless you're SMPTE. High THD will create harmonics, making a bad situation worse. You'll hear something is off, but not the degree and exactly what without proper instrumentation. Many people are accustomed to it and no longer notice their system's distortion. They sure do when they get it back working properly.
Yes. I often assess sound quality with piano and vocals. Other instruments can be helpful. High frequencies generate harmonics above your hearing, so are ineffective unless beating with lower frequencies to generate a sum and difference. You are arguing with someone using only 1/2 (or less) the information I have. Hmmm. I have over 50 years experience with live sound experience on top of that. I had to accept very early my ability to hear distortion wasn't better then the test instruments back then when properly used. I looked at spectrum, not just a pointer. By the late 1980's, test instrumentation had exceeded the ability of the human body to even perceive distortion products. It has continuously improved and we are so far beyond that arguing anyone can hear beyond what is measured is a comedy. Interpreting the results take a little skill at times, but the measurements are there and repeatable.
The takeaway is this. If you figure you can properly repair and adjust any sound equipment to perform properly without the right training and equipment, you are deluding yourself. You can make it make noise. With practice it may run for years. Properly? You do not know.
It doesn't matter, there is a lot above 7KHz and you're showing your total lack of knowledge. The basic point is, humans are not test instruments and have been proved incorrect time and time again over what low distortion is.
You do not have any reference at all. You haven't any clue as to what amounts of distortion you can detect and are confusing it with frequency response. If you want to argue how good the most adept human is at detecting distortion, then you better get ready to swallow all your pride and admit defeat. It isn't my job to educate any one person, I was educated and I suggest you take the journey. This is a waste of everyone's time who has figured out how poorly humans assess distortion.
Humans compare pretty well. We can sort out over time a good system from a less good system. Almost every single day I perform THD tests and my IMD tests are 19 KHz and 20 KHz. Most of us have a complete understanding of what these tests show and sound like. Your IMD test is going to show difference at 4 KHz, the standard is a 1 KHz unless you're SMPTE. High THD will create harmonics, making a bad situation worse. You'll hear something is off, but not the degree and exactly what without proper instrumentation. Many people are accustomed to it and no longer notice their system's distortion. They sure do when they get it back working properly.
Yes. I often assess sound quality with piano and vocals. Other instruments can be helpful. High frequencies generate harmonics above your hearing, so are ineffective unless beating with lower frequencies to generate a sum and difference. You are arguing with someone using only 1/2 (or less) the information I have. Hmmm. I have over 50 years experience with live sound experience on top of that. I had to accept very early my ability to hear distortion wasn't better then the test instruments back then when properly used. I looked at spectrum, not just a pointer. By the late 1980's, test instrumentation had exceeded the ability of the human body to even perceive distortion products. It has continuously improved and we are so far beyond that arguing anyone can hear beyond what is measured is a comedy. Interpreting the results take a little skill at times, but the measurements are there and repeatable.
The takeaway is this. If you figure you can properly repair and adjust any sound equipment to perform properly without the right training and equipment, you are deluding yourself. You can make it make noise. With practice it may run for years. Properly? You do not know.
@ anatech: I think we are not recognizing that the American consumer was just as culpable as the business managers, accountants, and politicians in causing the migration of production overseas. The desire for cheaper prices resulted in people buying more stuff made outside the US. True, American business oftentimes made some terrible products: poorly designed, using parts to meet a price point, and poorly manufactured in some instances. But the impetus was in at least 505 of the cases, a need to match offshore prices. Now we hardly make anything here, and the skill sets are going fast or completely gone.
My mantra: how much "stuff" do we really need to be happy? How big a house do we really need to be happy? How much car do we really need to be safely and efficiently transported? How many shirts, pants, shoes, hats, gloves, and a-other articles of clothing do we need; and do we really need to have new outfits each year? IMO, better to buy that high quality cashmere sweater that will last for a lifetime, rather than buying a Temu or Uniqlo item that may last 1 year.
That there are going to be many individuals, even on this forum, that will vehemently disagree with me - which is their right, of course - indicates the depth of the issue.
I do not know the answer, except to choose wisely myself. At least the topic at hand in this thread - reconditioning/repairing old audio equipment and updating them - is consistent with my philosophy. I mean, Adcom is high quality and American.
My mantra: how much "stuff" do we really need to be happy? How big a house do we really need to be happy? How much car do we really need to be safely and efficiently transported? How many shirts, pants, shoes, hats, gloves, and a-other articles of clothing do we need; and do we really need to have new outfits each year? IMO, better to buy that high quality cashmere sweater that will last for a lifetime, rather than buying a Temu or Uniqlo item that may last 1 year.
That there are going to be many individuals, even on this forum, that will vehemently disagree with me - which is their right, of course - indicates the depth of the issue.
I do not know the answer, except to choose wisely myself. At least the topic at hand in this thread - reconditioning/repairing old audio equipment and updating them - is consistent with my philosophy. I mean, Adcom is high quality and American.
Hi Halauhula,
Agreed. I have said many times, we as a people got where we are by voting with our dollars.
As for how much do we need? Not nearly as much as we have. I was pretty happy as a kid. I bought a watch recently. It has so many features, they interfere with telling the time. My favorite watch is my ancient Seiko, does nothing but tell time with hands on a dial. Looks nice too.
Agreed. I have said many times, we as a people got where we are by voting with our dollars.
As for how much do we need? Not nearly as much as we have. I was pretty happy as a kid. I bought a watch recently. It has so many features, they interfere with telling the time. My favorite watch is my ancient Seiko, does nothing but tell time with hands on a dial. Looks nice too.
It was amazing growing up in the 1970's without all of the "junk" that kids and adults consider required today. I had a bike, skateboard, and stereo. I was free to roam at will, just be home when the sun goes down. Taught common sense and personal responsibility. You were not being controlled by your electronic devices all day long. Life was good!
Dan
Dan
A bike, a stereo, and some records took EVERY cent you could muster, too. And if you wanted better than $69 special with 3” full rangers in particleboard boxes fed by a 700 milliwatt IC amplifier….. you learned how to build amplifiers and speakers. With salvaged transistors, re-wound transformers, and used a DIM BULB firing it up for the first time.
I found a dollar inflation calculator at the Federal Reserve Bank of Minneapolis: https://www.minneapolisfed.org/about-us/monetary-policy/inflation-calculator.
As I recall, first line record albums in 1968 were about $4.50 (if anyone has hard data, please correct me and set forth the source). According to the calculator, $4.50 is worth $40.68 in 2024. This supports my position that music was a relatively expensive good in that era, and careful consideration of the quality of music was needed at that time.
As I recall, first line record albums in 1968 were about $4.50 (if anyone has hard data, please correct me and set forth the source). According to the calculator, $4.50 is worth $40.68 in 2024. This supports my position that music was a relatively expensive good in that era, and careful consideration of the quality of music was needed at that time.
I is obvious to me that people that are helped by anatech to repair with his $$$$ of required test equipment, will sell off the 3 grand boxes like Parasound and McIntosh.. The rest of their blown class AB amps originally < 0.2% HD will go to the dump. Then they will buy some new switcher powered trash and get on the 6 year replacement treadmill. Forget diy repair. For example the O.P. in this thread has disappeared.
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6 years? I don’t even give it that.
OP might just have found out that he’s in over his head.
My personal philosophy on “repairing” is that all important parameters - power, distortion, load-driving ability are GBD. As long as you can verify that it is working according to the original design, with the tools one has, and the components you can GET it can be “fixed”. If you don’t have the tools to verify this, you can come up short. If the original design requires careful matching, cherry picking parts, or has to be tuned in on a distortion analyzer, so be it. Many do NOT. Very basic amplifiers can be repaired with a multimeter and a dim bulb. If this wasn’t the case, people couldn’t even build kits without an EE degree and a full laboratory. So many of those old amps come straight out of the RCA data books or use classic time tested topologies. This one is somewhat more advanced, and at a minimum, requires that you work slowly and carefully. The better equipped you are, the faster you’ll get from A to B, with less potential for disaster in between.
OP might just have found out that he’s in over his head.
My personal philosophy on “repairing” is that all important parameters - power, distortion, load-driving ability are GBD. As long as you can verify that it is working according to the original design, with the tools one has, and the components you can GET it can be “fixed”. If you don’t have the tools to verify this, you can come up short. If the original design requires careful matching, cherry picking parts, or has to be tuned in on a distortion analyzer, so be it. Many do NOT. Very basic amplifiers can be repaired with a multimeter and a dim bulb. If this wasn’t the case, people couldn’t even build kits without an EE degree and a full laboratory. So many of those old amps come straight out of the RCA data books or use classic time tested topologies. This one is somewhat more advanced, and at a minimum, requires that you work slowly and carefully. The better equipped you are, the faster you’ll get from A to B, with less potential for disaster in between.