ScottFan355
Super Member
What year would people say solid-state came into it's own and could reasonably compete with the sound of tubes?
What Year Did Solid-State Start Sounding Good?
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OMGCat!
Super Member
I'd say mid to late 70's solid state got ironed out and started sounding very nice. Seems like designers figured out how to voice the amplifiers how they wanted and the early harshness and thinness went away. When complimentary pairs of devices became more available things got even better.
nj pheonix
Lunatic Member
I suspect stuff came before but Mac was selling MC250s in '67
It wasn't all junk out of the gate. There was (probably still is a learning curve)
Marantz 7T preamp '65
3# series sansuis '67
It wasn't all junk out of the gate. There was (probably still is a learning curve)
Marantz 7T preamp '65
3# series sansuis '67
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Superampman
AK Member
1978 Boothroyd Stewart Meridian 105/103, and the Naim gear of course. Oh, and the Quad ss gear. The Brits were at the helm.
restorer-john
Addicted Member
In my opinion, it took two distinct jumps before SS killed off tubes entirely. That said, tubes were killed off by the massive solid state push before solid state was mature enough to be superior IMO.
The first was when manufacturers stopped taking tube designs that had germanium transistors patched in and started designing solid state from the ground up. Chassis designs stopped having point to point and grommeted transistors where tubes had once been and PCBs were used, creating quieter, better performing designs.
The second major jump IMO was silicon and particularly Japanese high powered complementary silicon, which meant we could finally connect our speakers directly to the output devices. Everything improved massively with complementary push pull silicon, so I reckon about 1972/3 was about the point where coupling caps and quasi complementary designs were essentially old hat for all manufacturers.
From then on, solid state just got better and better until IMO, a performance plateau was reached around 1989/90 when the Japanese economy ground to a halt, and with it, the massive R&D budgets of yore.
The first was when manufacturers stopped taking tube designs that had germanium transistors patched in and started designing solid state from the ground up. Chassis designs stopped having point to point and grommeted transistors where tubes had once been and PCBs were used, creating quieter, better performing designs.
The second major jump IMO was silicon and particularly Japanese high powered complementary silicon, which meant we could finally connect our speakers directly to the output devices. Everything improved massively with complementary push pull silicon, so I reckon about 1972/3 was about the point where coupling caps and quasi complementary designs were essentially old hat for all manufacturers.
From then on, solid state just got better and better until IMO, a performance plateau was reached around 1989/90 when the Japanese economy ground to a halt, and with it, the massive R&D budgets of yore.
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While it wasn't completely superior to the Audio Research SP-3a, the Mark Levinson JC-2 (circa '75) was a great contender in terms of preamps.
It wasn't until the late 70s when Threshold began contending with the best tube power amps. Even then, they couldn't fully compete in terms of harmonic realism with the midrange.
Early SS designs rooted in the 60s were dreadful.
I still prefer modern tube gear (Audio Research, VTL, et. al.) with massive power supplies over most SS gear today. Companies like Ayre and Pass Labs, however, make a great statement for how good SS can be today.
It wasn't until the late 70s when Threshold began contending with the best tube power amps. Even then, they couldn't fully compete in terms of harmonic realism with the midrange.
Early SS designs rooted in the 60s were dreadful.
I still prefer modern tube gear (Audio Research, VTL, et. al.) with massive power supplies over most SS gear today. Companies like Ayre and Pass Labs, however, make a great statement for how good SS can be today.
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My Sansui 2000A was introduced in 1969 and I think it sounds pretty good. Does it sound better than a good tube receiver? I don't know, all my tube stuff needs restored and the Sansui works (although it did need the noisy transistors replaced) so there's that... it does seem like the SS stuff is less likely to need restoration, although that may just be because the tube stuff is older.
I also have a Dynaco PAS-4/ST-120 combo (older yet) and I don't think it sounds awful, although the PAS-4 does seem to get a bad rap in stock form.
I also have a Dynaco PAS-4/ST-120 combo (older yet) and I don't think it sounds awful, although the PAS-4 does seem to get a bad rap in stock form.
Poinzy
Super Member
According to my father, it was the mid-to-late 1970s. Up to that point, he'd been building and servicing his own tube amps.
mhardy6647
Lunatic Member
Resisting the temptation to observe, snarkily, "I'm still waiting"... 
Some of the mid-late 1960s quasi-complementary soiled state amplifiers actually sound pretty good. E.g., I have an HH Scott LK-60 (kit version of the Scott 260 ss integrated amp) that is not bad sounding. It lacks the graininess and harshness common to early ss amplifiers. Big ol' DC blocking coupling caps to the speaker outputs probably round off the rough edges considerably
HH Scott LK60 DSC_0789 by Mark Hardy, on Flickr
Scan0008 by Mark Hardy, on Flickr
source: www.radioshackcatalogs.com (1966)
source: www.radioshackcatalogs.com (1967)
Some of the mid-late 1960s quasi-complementary soiled state amplifiers actually sound pretty good. E.g., I have an HH Scott LK-60 (kit version of the Scott 260 ss integrated amp) that is not bad sounding. It lacks the graininess and harshness common to early ss amplifiers. Big ol' DC blocking coupling caps to the speaker outputs probably round off the rough edges considerably
HH Scott LK60 DSC_0789 by Mark Hardy, on FlickrScan0008 by Mark Hardy, on Flickr
source: www.radioshackcatalogs.com (1966)
source: www.radioshackcatalogs.com (1967)
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restorer-john
Addicted Member
That's funny. Unintentional typo.
"Some of the mid-late 1960s quasi-complementary soiled state amplifiers actually sound pretty good."
Are you saying most sounded like sH#t?
"Some of the mid-late 1960s quasi-complementary soiled state amplifiers actually sound pretty good."
Are you saying most sounded like sH#t?
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Raynald
Addicted Member
Makes sense, I can attest to at least the second part. I was in audio retail mid 80's to early 90's and I saw things halt and actually go backwards with respect to build quality in that period.
1967
Superampman
AK Member
My Altec 9440A quasi-complimentary PA amp is superb sounding also circa 1975. However, the DD servo charge OTLs driving my Acoustat Monitor 3 are peerless so far ime. ESLs are clearly a reference, but until an ss amp is built with the voltage required to drive them directly, comparisons are but one sided.
Superampman
AK Member
Agreed, except for the high end gear. Although I do recall Dual's high end entry around that time mimicking Oracle's platform. Don't remember the model but it was just pure junk, all plastic, very cheaply made, for a cool grand.
paullehmann
New Member
Mr
Iwasaki Chiaki came in his review of luxman sq507x in the japanese hifi magazine
Swing Journal November issue (issued in October 1971) to the conclusion that ;
"The SQ 507 X released by Lux is the "first" product that can reach the level of SQ 38 FD just to overtake it"
japanese text here: http://audiosharing.com/review/?p=4928#comments
for those interested i insert this rather bad Google translation ;
Iwasaki Chiaki
Swing Journal November issue (issued in October 1971) From
'SJ selection new product listening notes'
Lux's new amplifier SQ507X to introduce here is the amplifier which is the most attractive in the product to be announced in the fall of 1970 and is not ashamed of the name of SJ selection which secured the quality which can fully meet the expectation.
As seen in the company's best-selling SQ38FD amplifier, Lux has commercialized and commercialized only the single tube type currently in the market today, with a very conservative color manufacturer .Nissei Moon, the pitch of technology is remarkable.Today, as a stereo manufacturer transistor amps can make their widths wider, the fact that SQ38FD is still being used as a product is on both the good side and the bad side of this manufacturer.
The good side, in spite of it being, is that it preserves the skill that luxury mania wants, and it is a stereo manufacturer boasting "understanding of music".It can be said that the bad side is making the reason why transistor makers made by this manufacturer are not as good as other companies, and the masterpiece SQ38FD has thinned the shadow of many Laks made transistor and amp It is a fact.
For those who know the high quality of Lux's amplifier, probably not worrying that it will not be possible to keep the position of Lux as an amplifier manufacturer in the future without hitting the image of SQ38 FD It is a common concern and it must have been an expectation for future amplifiers as well.
The SQ 507 X released by Lux is the "first" product that can reach the level of SQ 38 FD just to overtake it.
When I touched the sound of this amp, the contents of this amp had almost never changed from the already released SQ 505 X. I was told that I just switched the power stage to a powerful stone and uploaded the output, I doubted it It is so.In other words, compared with SQ 505 X, the improvement of the tone is clear.<AFrom i = 6> depth and moist sounds, I can hardly imagine the same circuit scheme as SQ505X.Daringly, it can be said that it is a sound close to the JBL amplifier, and it can be said that it inherits the beautiful sound peculiar to SQ 38F. For me who is captive of jazz sound, the sound of Lux's transistor amp, which I have touched up so far, always tastes enough of attack and dullness, but for this SQ 507 X There was not at all.The power of solo by alto and tenor, the resonance which the piano's attack gotchiri, both SQ507X fired out spectacularly.The glow of the cymbals and the thick swells of the bass were reproduced easily.This depth was comparable to the powerful base obtained in SQ 38 FD, and the glow of the trumpet surpassed even the SQ 38 FD.As this moist, if you seek a brilliant moisture other than that, JBL is the only transistor / amplifier. This glossy and straightforward sound must be a product resulting from a fusion of all tiers directly connected with a tone control circuit of a simple constitution peculiar to LUX.If it adds further, it will be in a composition that wasteful of the waste and dropped meat meat entirely without increasing the composition stage at once. Besides, the weight of 11 kg of this amplifier means relaxed regulation of the power supply circuit, and it will show enough consideration of thorough manufacturers' technical staff up to the invisible place. SQ507X which Lucks took on the pride and quality as the highest grade product of all stages directly connected amplifiers such as SQ505X, 503X, which Lucks saw this autumn, is probably a powerful indexing force for future development of this manufacturer .I = 7> If I am captured by the jazz sound, the sound of the Lux's transistor amp, which I have touched up so far, always tastes the attraction and dullness of the tooth for the attack, but on this SQ 507 X There was not it at all.The power of solo by alto and tenor, the resonance which the piano's attack gotchiri, both SQ507X fired out spectacularly.The glow of the cymbals and the thick swells of the bass were reproduced easily.This depth was comparable to the powerful base obtained in SQ 38 FD, and the glow of the trumpet surpassed even the SQ 38 FD.As this moist, if you seek a brilliant moisture other than that, JBL is the only transistor / amplifier.This glossy and straightforward sound must be a product resulting from a fusion of all tiers directly connected with a tone control circuit of a simple constitution peculiar to LUX.If it adds further, it will be in a composition that wasteful of the waste and dropped meat meat entirely without increasing the composition stage at once.Besides, the weight of 11 kg of this amplifier means relaxed regulation of the power supply circuit, and it will show enough consideration of thorough manufacturer technical teams to the invisible place.SQ507X that Lucks embarked on the pride and quality as the highest grade product of all stages directly connected amplifiers such as SQ505X, 503X, which Lux was made this fall, it is probably a powerful indexing force for future development of this manufacturer .I = 7> If I am captured by the jazz sound, the sound of the Lux's transistor amp, which I have touched up so far, always tastes the attraction and dullness of the tooth for the attack, but on this SQ 507 X There was not it at all.The power of solo by alto and tenor, the resonance which the piano's attack gotchiri, both SQ507X fired out spectacularly.The glow of the cymbals and the thick swells of the bass were reproduced easily.This depth was comparable to the powerful base obtained in SQ 38 FD, and the glow of the trumpet surpassed even the SQ 38 FD.As this moist, if you seek a brilliant moisture other than that, JBL is the only transistor / amplifier.This glossy and straightforward sound must be a product resulting from a fusion of all tiers directly connected with a tone control circuit of a simple constitution peculiar to LUX.If it adds further, it will be in a composition that wasteful of the waste and dropped meat meat entirely without increasing the composition stage at once.Besides, the weight of 11 kg of this amplifier means relaxed regulation of the power supply circuit, and it will show enough consideration of thorough manufacturers' technical staff up to the invisible place.SQ507X that Lucks embarked on the pride and quality as the highest grade product of all stages directly connected amplifiers such as SQ505X, 503X, which Lux was made this fall, it is probably a powerful indexing force for future development of this manufacturer .I = 8> This glossy and straightforward sound must be a product resulting from the fusion of the tone control circuit with a simple structure unique to LUX and all stages directly connected.If it adds further, it will be in a composition that wasteful of the waste and dropped meat meat entirely without increasing the composition stage at once.Besides, the weight of 11 kg of this amplifier means relaxed regulation of the power supply circuit, and it will show enough consideration of thorough manufacturers' technical staff up to the invisible place.SQ507X which Lucks took on the pride and quality as the highest grade product of all stages directly connected amplifiers such as SQ505X, 503X, which Lucks saw this autumn, is probably a powerful indexing force for future development of this manufacturer .I = 8> This glossy and straightforward sound must be a product resulting from the fusion of the tone control circuit with a simple structure unique to LUX and all stages directly connected.If it adds further, it will be in a composition that wasteful of the waste and dropped meat meat entirely without increasing the composition stage at once.Besides, the weight of 11 kg of this amplifier means relaxed regulation of the power supply circuit, and it will show enough consideration of thorough manufacturers' technical staff up to the invisible place.SQ507X which Lucks took on the pride and quality as the highest grade product of all stages directly connected amplifiers such as SQ505X, 503X, which Lucks saw this autumn, is probably a powerful indexing force for future development of this manufacturer .
I spend some very formative musical years with a luxman sq507x buying a secondhand example at age 18 loved it until it was stolen after 6 years.
i was not able to find a satisfying replacement nothing sounded just right and i actually stopped listening to music for many years not being able to find that special magic again.
lately - in the last 5 years i have like so many others of my age backtracked in search of lost joys and have made a small Collection after i first recreated that magic setup from my youth and later fell victim to the notorius hifi bug.
so i have the 507 precessor to the 507x which are SEPP OTL capacitor coupled versus the later 507x which are pure complementary of a modern design.
there is quite a leap ind sq between these units which supports restorer-johns commentary.
Paul lehmann
Iwasaki Chiaki came in his review of luxman sq507x in the japanese hifi magazine
Swing Journal November issue (issued in October 1971) to the conclusion that ;
"The SQ 507 X released by Lux is the "first" product that can reach the level of SQ 38 FD just to overtake it"
japanese text here: http://audiosharing.com/review/?p=4928#comments
for those interested i insert this rather bad Google translation ;
Iwasaki Chiaki
Swing Journal November issue (issued in October 1971) From
'SJ selection new product listening notes'
Lux's new amplifier SQ507X to introduce here is the amplifier which is the most attractive in the product to be announced in the fall of 1970 and is not ashamed of the name of SJ selection which secured the quality which can fully meet the expectation.
As seen in the company's best-selling SQ38FD amplifier, Lux has commercialized and commercialized only the single tube type currently in the market today, with a very conservative color manufacturer .Nissei Moon, the pitch of technology is remarkable.Today, as a stereo manufacturer transistor amps can make their widths wider, the fact that SQ38FD is still being used as a product is on both the good side and the bad side of this manufacturer.
The good side, in spite of it being, is that it preserves the skill that luxury mania wants, and it is a stereo manufacturer boasting "understanding of music".It can be said that the bad side is making the reason why transistor makers made by this manufacturer are not as good as other companies, and the masterpiece SQ38FD has thinned the shadow of many Laks made transistor and amp It is a fact.
For those who know the high quality of Lux's amplifier, probably not worrying that it will not be possible to keep the position of Lux as an amplifier manufacturer in the future without hitting the image of SQ38 FD It is a common concern and it must have been an expectation for future amplifiers as well.
The SQ 507 X released by Lux is the "first" product that can reach the level of SQ 38 FD just to overtake it.
When I touched the sound of this amp, the contents of this amp had almost never changed from the already released SQ 505 X. I was told that I just switched the power stage to a powerful stone and uploaded the output, I doubted it It is so.In other words, compared with SQ 505 X, the improvement of the tone is clear.<AFrom i = 6> depth and moist sounds, I can hardly imagine the same circuit scheme as SQ505X.Daringly, it can be said that it is a sound close to the JBL amplifier, and it can be said that it inherits the beautiful sound peculiar to SQ 38F. For me who is captive of jazz sound, the sound of Lux's transistor amp, which I have touched up so far, always tastes enough of attack and dullness, but for this SQ 507 X There was not at all.The power of solo by alto and tenor, the resonance which the piano's attack gotchiri, both SQ507X fired out spectacularly.The glow of the cymbals and the thick swells of the bass were reproduced easily.This depth was comparable to the powerful base obtained in SQ 38 FD, and the glow of the trumpet surpassed even the SQ 38 FD.As this moist, if you seek a brilliant moisture other than that, JBL is the only transistor / amplifier. This glossy and straightforward sound must be a product resulting from a fusion of all tiers directly connected with a tone control circuit of a simple constitution peculiar to LUX.If it adds further, it will be in a composition that wasteful of the waste and dropped meat meat entirely without increasing the composition stage at once. Besides, the weight of 11 kg of this amplifier means relaxed regulation of the power supply circuit, and it will show enough consideration of thorough manufacturers' technical staff up to the invisible place. SQ507X which Lucks took on the pride and quality as the highest grade product of all stages directly connected amplifiers such as SQ505X, 503X, which Lucks saw this autumn, is probably a powerful indexing force for future development of this manufacturer .I = 7> If I am captured by the jazz sound, the sound of the Lux's transistor amp, which I have touched up so far, always tastes the attraction and dullness of the tooth for the attack, but on this SQ 507 X There was not it at all.The power of solo by alto and tenor, the resonance which the piano's attack gotchiri, both SQ507X fired out spectacularly.The glow of the cymbals and the thick swells of the bass were reproduced easily.This depth was comparable to the powerful base obtained in SQ 38 FD, and the glow of the trumpet surpassed even the SQ 38 FD.As this moist, if you seek a brilliant moisture other than that, JBL is the only transistor / amplifier.This glossy and straightforward sound must be a product resulting from a fusion of all tiers directly connected with a tone control circuit of a simple constitution peculiar to LUX.If it adds further, it will be in a composition that wasteful of the waste and dropped meat meat entirely without increasing the composition stage at once.Besides, the weight of 11 kg of this amplifier means relaxed regulation of the power supply circuit, and it will show enough consideration of thorough manufacturer technical teams to the invisible place.SQ507X that Lucks embarked on the pride and quality as the highest grade product of all stages directly connected amplifiers such as SQ505X, 503X, which Lux was made this fall, it is probably a powerful indexing force for future development of this manufacturer .I = 7> If I am captured by the jazz sound, the sound of the Lux's transistor amp, which I have touched up so far, always tastes the attraction and dullness of the tooth for the attack, but on this SQ 507 X There was not it at all.The power of solo by alto and tenor, the resonance which the piano's attack gotchiri, both SQ507X fired out spectacularly.The glow of the cymbals and the thick swells of the bass were reproduced easily.This depth was comparable to the powerful base obtained in SQ 38 FD, and the glow of the trumpet surpassed even the SQ 38 FD.As this moist, if you seek a brilliant moisture other than that, JBL is the only transistor / amplifier.This glossy and straightforward sound must be a product resulting from a fusion of all tiers directly connected with a tone control circuit of a simple constitution peculiar to LUX.If it adds further, it will be in a composition that wasteful of the waste and dropped meat meat entirely without increasing the composition stage at once.Besides, the weight of 11 kg of this amplifier means relaxed regulation of the power supply circuit, and it will show enough consideration of thorough manufacturers' technical staff up to the invisible place.SQ507X that Lucks embarked on the pride and quality as the highest grade product of all stages directly connected amplifiers such as SQ505X, 503X, which Lux was made this fall, it is probably a powerful indexing force for future development of this manufacturer .I = 8> This glossy and straightforward sound must be a product resulting from the fusion of the tone control circuit with a simple structure unique to LUX and all stages directly connected.If it adds further, it will be in a composition that wasteful of the waste and dropped meat meat entirely without increasing the composition stage at once.Besides, the weight of 11 kg of this amplifier means relaxed regulation of the power supply circuit, and it will show enough consideration of thorough manufacturers' technical staff up to the invisible place.SQ507X which Lucks took on the pride and quality as the highest grade product of all stages directly connected amplifiers such as SQ505X, 503X, which Lucks saw this autumn, is probably a powerful indexing force for future development of this manufacturer .I = 8> This glossy and straightforward sound must be a product resulting from the fusion of the tone control circuit with a simple structure unique to LUX and all stages directly connected.If it adds further, it will be in a composition that wasteful of the waste and dropped meat meat entirely without increasing the composition stage at once.Besides, the weight of 11 kg of this amplifier means relaxed regulation of the power supply circuit, and it will show enough consideration of thorough manufacturers' technical staff up to the invisible place.SQ507X which Lucks took on the pride and quality as the highest grade product of all stages directly connected amplifiers such as SQ505X, 503X, which Lucks saw this autumn, is probably a powerful indexing force for future development of this manufacturer .
I spend some very formative musical years with a luxman sq507x buying a secondhand example at age 18 loved it until it was stolen after 6 years.
i was not able to find a satisfying replacement nothing sounded just right and i actually stopped listening to music for many years not being able to find that special magic again.
lately - in the last 5 years i have like so many others of my age backtracked in search of lost joys and have made a small Collection after i first recreated that magic setup from my youth and later fell victim to the notorius hifi bug.
so i have the 507 precessor to the 507x which are SEPP OTL capacitor coupled versus the later 507x which are pure complementary of a modern design.
there is quite a leap ind sq between these units which supports restorer-johns commentary.
Paul lehmann
Lavane
Lunatic Member
Gotta agree here. Add properly restored Marantz model 15, 16 and 16B SS power amps and boy do they sound good. I restored a model 33, the one after the 7T and a matching model 16 a couple years ago. Some late '60's and early '70's SS equipment was pretty nice.
I am just guessing here, but this is how I feel.
They started out with Germanium transistors, they are non linear, low voltage. Around late 60s ( I think), silicon transistor first came out and marked a significant improvement. But still, breakdown voltage is low and most have fT only in 2MHz to 3MHz. Example is 2N3055. High rail voltage is the key to get high power output and more head room. BJT has problem of sticking to the rail when clipped and it will make it sound bad. People like Nelson Pass came out with very complicated design in the Threshold 800 that stack two emitter follower transistor to handle the high voltage rails.
Also, transistor circuits are so different from tubes, for one, you have only one polarity with tubes, but you can have NPN and PNP transistors. It's like tube is similar with NPN, so the design of tube amps are around this. People in the early days really did not know how to design. But in the early 70s, people learn and got better. If you look at the design, they are very close to the modern designs already.
In the early 80s, high voltage power transistors are available and that gave a significant improvement. Also then in the late 80s, the 80MHz transistor became available and that result in a big jump in quality. Designs really stay the same since the late 80s for BJT amps till today. I bought a Nakamichi Stasis PA-7 designed by Nelson Pass from the late 80s, it is still very competitive with the very high end amps today.
Then MOSFET amps came into the market, Nelson Pass was one of those that switch from Stasis to MOSFET based Aleph and his newer amps. MOSFET like tubes, they don't stick to the rail when clipped.
Design is a lot more mature now, it has not been changed much since the 80s. SS power amps are basically a big discrete opamp, the internal circuit is almost the same. The design benefit from opamp development also. It become quite standard. Mainly it is low THD design, very different from tube amp that distort in a "good" way. Tube amp work with the speaker, SS amp just drive and doesn't care about the speakers.
One thing I cannot help but to put in my 2cents. SS amp drives the speaker and rely on high damping factor. To get the best out of SS amps, you need very beefy cables. I used multiple pairs of cables to drive each speaker. I don't want to bore you with it as I have been talking about this many times.
They started out with Germanium transistors, they are non linear, low voltage. Around late 60s ( I think), silicon transistor first came out and marked a significant improvement. But still, breakdown voltage is low and most have fT only in 2MHz to 3MHz. Example is 2N3055. High rail voltage is the key to get high power output and more head room. BJT has problem of sticking to the rail when clipped and it will make it sound bad. People like Nelson Pass came out with very complicated design in the Threshold 800 that stack two emitter follower transistor to handle the high voltage rails.
Also, transistor circuits are so different from tubes, for one, you have only one polarity with tubes, but you can have NPN and PNP transistors. It's like tube is similar with NPN, so the design of tube amps are around this. People in the early days really did not know how to design. But in the early 70s, people learn and got better. If you look at the design, they are very close to the modern designs already.
In the early 80s, high voltage power transistors are available and that gave a significant improvement. Also then in the late 80s, the 80MHz transistor became available and that result in a big jump in quality. Designs really stay the same since the late 80s for BJT amps till today. I bought a Nakamichi Stasis PA-7 designed by Nelson Pass from the late 80s, it is still very competitive with the very high end amps today.
Then MOSFET amps came into the market, Nelson Pass was one of those that switch from Stasis to MOSFET based Aleph and his newer amps. MOSFET like tubes, they don't stick to the rail when clipped.
Design is a lot more mature now, it has not been changed much since the 80s. SS power amps are basically a big discrete opamp, the internal circuit is almost the same. The design benefit from opamp development also. It become quite standard. Mainly it is low THD design, very different from tube amp that distort in a "good" way. Tube amp work with the speaker, SS amp just drive and doesn't care about the speakers.
One thing I cannot help but to put in my 2cents. SS amp drives the speaker and rely on high damping factor. To get the best out of SS amps, you need very beefy cables. I used multiple pairs of cables to drive each speaker. I don't want to bore you with it as I have been talking about this many times.
