Historical expose. Development of better performing transistors for hifi.

[DanielT]

Anyone know a little about it? Now I think from a historical perspective. For example, decade or year Sanken transistor Y which enabled better... Year / decade came hybrid Z.

The origin of thread wire comes from this thread where ZolaIII writes about, among other things, the transistor 2N3773:

"That (N2) is not stellar performer (just average) but it whose quite a work house and widely used especially for a stage (active mixers / amplifiers and cetera) equipment. Biggest advantage they arguably have even today is how easy it is to get to some of those that are still in working condition (patch, replace and carry on). There are far better solutions from the end of AB class era such as late STK higher end first gen hybrids for instance.

In short engineering - testing - back to drowning board process trough whole development cycle.
Those late STK's had a spec's similar to today's top D class circuits (second gen D class hybrid). You for instance still have plane AB class transistor amps which perform admirably enough (better than cheap class D one's) especially considering the price (for instance Sanken ones in Yamaha Amp's and active speakers).
Even today we usually take up to 1% THD power rating for power amplifiers as acceptable."

Why 12 power transistors in a class AB (?)120 W (?) amplifier?

It is to stay within the SOA of the transistors so their max. power ratings are never reached. SOA stands for Safe Operating Area At any voltage across the transistor a specific current is allowed. This is the SOA. When amps must deliver high output power (so high voltages and high currents)...

audiosciencereview.com

Anyway, I'm curious. Hopefully others are interested too. Sound / hifi history.

 

[DanielT]

I did a simpler basic, mainly Wikipedia, check regarding transistors, sound, hifi.

First, if one is to study transistors and their development, one immediately realizes the influence of transistors and the development of our modern society. It has been and is huge. For those who missed it, I think it belongs to general education to know it. Regardless of whether you are interested of hifi or not. For those who do not know the history of transistors, it is just back to school. Wikipedia school for example ..
The small world well-sounding amplifier in Hifi is in this context only a small part.

Transistor - Wikipedia

en.wikipedia.org

So transistors used in amplifiers for HiFi, or "High end" then. It may seem like a bit more pin ponit for this forum .. Well then I fairly immediately get into the question of how amplifiers work. This is also too big of an issue for this thread. This requires a more comprehensive review, for example of:

"Douglas Self is a British electronics engineer and author with a particular interest in audio. He received a first class honors degree in engineering from Cambridge University, and then studied psychoacoustics at Sussex University. [1] He is the author of six books on audio electronics, published by Focal Press. [2] He has also contributed many articles to Wireless World magazine, some of which were compiled into a book along with articles by Peter Baxandall. [3] [4] [5]

Self's books have been well received. His Audio Power Amplifier Design Handbook was recommended by Walt Jung and described as "famous" by audio website hifisonix. [9] [10] The second edition of his Small Signal Audio Design received a very positive review in Sound on Sound magazine. [11]"

Douglas Self - Wikipedia

en.wikipedia.org

So what has this now hummed into. Not much more than that it is important to specify what you are interested in. It is difficult to talk about something specific without taking into account the whole.

Should you go into more detail about the construction of amplifiers and transistors, for example the mentioned 2n3773.Well, just for concrete constructions and design, ASR is probably not the best place. ASR is more, as I see it, a forum that deals with Hifi from a theoretical perspective. As I understand it, even though there is a DIY section on ASR .. That is probably more suitable for dedicated DIY forum, for example this :

A simple stereo Amp aroud a 2N3773

I'm pretty sure the RCA device came first. And of course the 3055 before 3773 - they issued the part numbers in sequence until complementary pairs messed this all up. In that time, various types was divided into groups resp. families by RCA (see also PDF attachement): 1) 2N3771 Family (related...

www.diyaudio.com

I think the best thing to learn about transistors is to alternate theory and practice. Build the simplest of simplest amplifiers. An exercise that I think everyone who is interested in Hifi would learn from. Even for those who have never held a soldering iron, who only have a little vague knowledge about what, for example, resistor, capacitor has for functions in an amplifier.

The simplest of the simple with transistor 2n3773. Just to successfully get sound. After that, maybe the DIY devil will bite you

After that something like:

Then follow transistors and hybrids, integrated circuits and HiFi, but that will be in another thread.

 

[pma]

I am sorry this was covered so many times. Please go through this book, chapter 6, page 164 rather than asking for simple opinions here.

https://d1.amobbs.com/bbs_upload782111/files_29/ourdev_554203.pdf

 

[DanielT]

You are absolutely right PMA, I realized difficulties in addressing this with transistors and HiFi, from a general perspective. It's a big topic. Hence my second post in this thread.

Better to then on the basis of more concrete issues address this with transistors and amplifiers, as I did here:

Why 12 power transistors in a class AB (?)120 W (?) amplifier?

Why 12 power transistors in a class AB (?)120 W (?) amplifier in .. 4-8 Ohm (?) What is the point of 6 power transistors per channel in such an amplifier? Information and pictures below . I would be very grateful for clarification. The stuff works, but I'm just curious. :) Some facts. Sela, a...

audiosciencereview.com

 

[Cbdb2]

Better transistors are just better transistors, they weren't developed for Hifi. Anyone who uses power transistors would benefit from higher beta, less beta droop, higher power handling, higher Vce etc. So the title of this thread is misleading, it doesn't need the "hifi".

 

[DanielT]

No, it became a rather unfocused thread, I have to take it on me.. Sorry .. Too big topic in itself, I think. In any case, it is as it is now.

 

[EJ3]

I am sorry this was covered so many times. Please go through this book, chapter 6, page 164 rather than asking for simple opinions here.

https://d1.amobbs.com/bbs_upload782111/files_29/ourdev_554203.pdf

I am sorry too. There are those like me that have never even heard of this stuff. & you could have chosen gently directing those of us whom it would benefit as to where to find it. Which is what was being done for us neophytes. If you don't need this section and can't be bothered to help those who don't yet know: Please skip ahead. I am here for learning. Thank you for making that more difficult.

 

[DanielT]

. Thank you...

I'm so happy to help you.

Here look at some fun pictures instead:

Nice event.

Hifi Vintage DIY fair with pictures

I visited this fair yesterday! DIY & Vintage meeting in Mölnlycke Here is a short report. When: 6 November 2021 Where: Country: Sweden City: Gothenburg I took pictures myself BUT most were so damn blurred so I borrow pictures from this thread, taken by other participants. Pictures taken from...

audiosciencereview.com

Sometimes you get decent threads sometimes not. I wrote in the thread that it went wrong, on my part.

You win some, lose some ...

 

[audio2design]

I am sorry this was covered so many times. Please go through this book, chapter 6, page 164 rather than asking for simple opinions here.

https://d1.amobbs.com/bbs_upload782111/files_29/ourdev_554203.pdf

Newbie / Beginner forum. Why the attitude?

 

[audio2design]

Better transistors are just better transistors, they weren't developed for Hifi. Anyone who uses power transistors would benefit from higher beta, less beta droop, higher power handling, higher Vce etc. So the title of this thread is misleading, it doesn't need the "hifi".

Except they were in many cases developed targetting audio w.r.t. specs as it was the largest market by far for these specs at the time.

 

[DanielT]

Except they were in many cases developed targetting audio w.r.t. specs as it was the largest market by far for these specs at the time.

You seem to know your stuff audio2design. I found this online. I assume that you know the technology that emerges in that video regarding transistors. I paste it the video most, well because it's still a time travel almost 60 years back in time.That in itself can be interesting. See what applied in 1965. Plus someone else might think it might be fun to watch. Wondering what has gotten better, changed with transistors since then? As a happy amateur, I can still ask the question, even if I do not know the answer. Well, that's why I'm asking the question, he he.

 

[restorer-john]

Better transistors are just better transistors, they weren't developed for Hifi. Anyone who uses power transistors would benefit from higher beta, less beta droop, higher power handling, higher Vce etc. So the title of this thread is misleading, it doesn't need the "hifi".

You'd be wrong there. Plenty of development from all the major semiconductor makers went into producing better transistors specifically for high fidelity amplification, especially in the mid-late 1970s and into the 1980s. And we had MOSFETs specifically created for audio from the likes of Hitachi and Toshiba. Fujitsu, Sanken and Hitachi also created the RETs/LAPTs for highly linear audio applications.

I could rattle off lists of hundreds of transistors that were only made for audio and many that were specifically designed to an audio manufacturer's specification and not available to anyone else.

Think of the Thermal track transistors from ON. Specifically made for audio amplifiers:

The small world well-sounding amplifier in Hifi is in this context only a small part.

Maybe in this day and age, but certainly not in the 1970s and 1980s. There was nothing bigger and the industry was absolutely enormous.

Those late STK's had a spec's similar to today's top D class circuits (second gen D class hybrid). You for instance still have plane AB class transistor amps which perform admirably enough (better than cheap class D one's) especially considering the price (for instance Sanken ones in Yamaha Amp's and active speakers).
Even today we usually take up to 1% THD power rating for power amplifiers as acceptable."

Sanyo's thick film hybrids (STKs) were cheap. That's all. They were never very good, dreadfully easy to destroy and just a poor man's option. Basically, they were a amplifier solution for low-mid end commodity rack systems. Don't let anyone tell you otherwise.

No remotely serious amplifier aspiring to high performance would use them. Some voltage amp STKs were OK, but you still had to hold your breath and hope they survived an output stage failure (usually they didn't).

 

[ZolaIII]

Just to explain what made late STK's good. At the time Sonyo had a majority of audio industry behind it (Denon, Sonyo, Onkyo, Martinez to name a few). The arch rival whose Philips with it's TDA (now part of NXP semi) similar designed AB hibrid line and far less supporter's. The early STK's ware actually worse than competition and they designer's ware ashamed. So they got the design back to drowning board. The redesign whose as good as competition or better and had a wide adoption. But designers where eager to try to get more and it happened that third time whose a charm, they made a high end part's but industry whosent interested in it because of higher price and the fact they warent really interested in such high end with limited market interest in it. So those never seen wider adoption. Important part to remember is that what made them stand out is redesign and general effort to perfect the design.

 

[DanielT]

A while ago I opened up my mother's receiver Luxor 5082 R. See here what's in it:

What do you think about them? Debris? You can say as it is. My mother does not care so much about the sound quality, he he.

Description
Luxor Professional 5082-R receiver manufactured by Luxman in Japan during the late 1970s and sold, among other things, by Luxor in Sweden.

Manufactured by Luxman well, the Swedish company Luxor had the agency for Luxman in Sweden. I've never heard of Luxman making any receivers for Luxor. Perhaps the development engineers exchanged ideas with each other. Can I guess, but no more than that.

RECEIVER, Luxor Professional 5082-R.

Luxor Professional 5082-R receiver tillverkad av Luxman i Japan under slutet av 1970-talet och såld bland annat av Luxor i Sverige.

auctionet.com

https://www.hifigoteborg.se/Luxor%205082%20R%20%20spec.htm

 

[restorer-john]

@ZolaIII I have to agree that the really late STKs were considerably better than the early ones for sure.

The big adopter of those was Matsushita, who co-developed a bunch of them for their "New Class A" designs and several of them were very high powered. But, they were still hybrids, with small die sizes and by that time, they were expensive (due to being bespoke designs).

Philips were never really in the game at that point and in fact, they used plenty of Sanyo STKs in their Marantz (they owned them) branded amplifiers made by SRC in Japan. Even into the 90s, Philips owned Marantz were filling even their higher range amplifiers with Sanyo STK VA stages.

 

[restorer-john]

A while ago I opened up my mother's receiver Luxor 5082 R. See here what's in it:

View attachment 164046

What do you think about them? Debris? You can say as it is. My mother does not care so much about the sound quality, he he.

Description
Luxor Professional 5082-R receiver manufactured by Luxman in Japan during the late 1970s and sold, among other things, by Luxor in Sweden.

Manufactured by Luxman well, the Swedish company Luxor had the agency for Luxman in Sweden. I've never heard of Luxman making any receivers for Luxor. Perhaps the development engineers exchanged ideas with each other. Can I guess, but no more than that.

RECEIVER, Luxor Professional 5082-R.

Luxor Professional 5082-R receiver tillverkad av Luxman i Japan under slutet av 1970-talet och såld bland annat av Luxor i Sverige.

auctionet.com

https://www.hifigoteborg.se/Luxor%205082%20R%20%20spec.htm

There's absolutely nothing Lux corporation about that "Luxor". A few pushbuttons on the front panel and a name like "Luxor" does not a Luxman make. It looks more like a Comet or low end Pioneer style OEM to me. Anyone could have made it, but Lux it is not.

It looks to be about 1977 to me. Hard to tell, but the date code will be on the top of the PSU caps (can't read it). It's not totally horrible, but not exactly state of the art then, or now.

 

[ZolaIII]

@restorer-john I want to show the path to perfecting the design from something which started as a failure into something good and how work and continuity actually means the most. All tho audio industry whose in the full swing then and it will probably never again reach that highs unfortunately industrial trends remain the same (make it cheaper by future integration and embrace of new class D hybrids).

Best regards to you and I hope you will find time to educate all of us especially blokes such as Daniel which are eager to learn.

 

[DanielT]

There's absolutely nothing Lux corporation about that "Luxor". A few pushbuttons on the front panel and a name like "Luxor" does not a Luxman make. It looks more like a Comet or low end Pioneer style OEM to me. Anyone could have made it, but Lux it is not.

It looks to be about 1977 to me. Hard to tell, but the date code will be on the top of the PSU caps (can't read it). It's not totally horrible, but not exactly state of the art then, or now.

Thanks for the reply! Interesting

This is how it was as far as I know.Luxor, the company, sold Luxman products through its sales chain in Sweden but that is a completely different matter.Sellers of the vintage receiver Luxor 5082R to increase value, throw in Luxman (brands sell) as a way to get the price up is probably the explanation.If they then know what it really was like with the collaboration, I do not know.

The electrolytes in the receiver Luxor 5082 R:

 

[DanielT]

Best regards to you and I hope you will find time to educate all of us especially blokes such as Daniel which are eager to learn.

I agree 100%. Thanks restorer-john!

You too ZolaIII and audio2design , thanks

 

[audio2design]

You seem to know your stuff audio2design. I found this online. ....... Wondering what has gotten better, changed with transistors since then? As a happy amateur, I can still ask the question, even if I do not know the answer. Well, that's why I'm asking the question, he he.

I have been around electronics / audio for a long time, and even though I have designed a lot of stuff, I would not consider myself an expert on the progression of transistors in audio. @restorer-john seems to have the leg up in that regard.

I think you asked an interesting question, and sounds like the types of articles that used to be in EE Times, back when it had pretty good content. You would need to pick a particular technology, either BJT, or MOSFET, then pick a variety of popular parts along the time line, then analyze the data sheets and look at what values changed, and what features became available, i.e. like better matching of NPN/PNP pairs.