Historical expose. Development of better performing transistors for hifi.

[audio2design]

I was intrigued and did some quick "bathroom" reading on Luxor. I had never heard of them. It seems they had a long history of building products many of which they designed themselves, though I expect some under license as well. They did rebadge Luxman receivers, but the one in the link does not have the "look" of Luxman, notably the two knobs in the upper right. That seems to be Sherwood/Nikko/Kenwood style. Sherwood did make some crap and some good stuff back in the day.

 

[tomtoo]

Nice entertaining docu about the transistor.

 

[DanielT]

I was intrigued and did some quick "bathroom" reading on Luxor. I had never heard of them. It seems they had a long history of building products many of which they designed themselves, though I expect some under license as well. They did rebadge Luxman receivers, but the one in the link does not have the "look" of Luxman, notably the two knobs in the upper right. That seems to be Sherwood/Nikko/Kenwood style. Sherwood did make some crap and some good stuff back in the day.

Interesting!

Sound and Hifi history is interesting, I think. Luxor was not known for "High end" directly. It was electronics for the people, the masses. In this way, they played a much bigger role than their focus had been a small "High end" hifi company. You could say they sounded the folk home. Luxor also manufactured TVs and computers.

However, "better hifi".Luxor created the series they called Professional with the purpose, I suspect to enter the then growing market of "better Hifi".

The saga of Luxor - from tube assembly to digital boxes.

1922 Axel Holstensson is interested in a pair of headphones and other parts for radio receivers at a trade fair in Leipzig, Germany.

1923 Together with, among others, his brother Karl, Axel Holstensson starts manufacturing tube receivers in a loft in simple forms. At the same time, the company Luxor is formed. The name is on everyone's lips after the discovery last year of the tomb of the Egyptian pharaoh Tutankhamun near the city of Luxor.

2002 On March 26, the news comes that production in Motala will be shut down. 620 are affected. Officially, the order situation is bad and customers demand products that can be assembled cheaper.
But is there any demand for digital boxes at all? Nokia, which still ordered the goods, decides a few months later to discontinue its development of the product.

Sagan om Luxor

Luxor 3-tube receiver from 1929:

 

[audio2design]

Interesting!

Interesting. It sounds in some ways like a company near me where I grew up (Canada) called Electrohome: https://en.wikipedia.org/wiki/Electrohome

There last remaining large business, cinema projectors, was bought by Christie, so when you see Christie Digital at the theater, that is them. Missing in that Wikipedia article is that at one point, they were making 10's of thousands of Atari 2600 game consoles per week.

 

[bothu]

This is my contribution to this thread with my "pre electric" audio equipment.
The radio is made 1926 in Motala by the Luxor company.
The record player have no brand name but must be from the same time as the radio.

A time in Swedish history where electricity not where common in homes.
But the need for news and entertainment was the same as today.

 

[DanielT]

Interesting. It sounds in some ways like a company near me where I grew up (Canada) called Electrohome: https://en.wikipedia.org/wiki/Electrohome

There last remaining large business, cinema projectors, was bought by Christie, so when you see Christie Digital at the theater, that is them. Missing in that Wikipedia article is that at one point, they were making 10's of thousands of Atari 2600 game consoles per week.

Exciting.

Very similar types of companies Electrohome and Luxor.

The companies that produced sound and image (TV) and various electronics for the people. Part of the modern technological history and the emergence of modern society.

With the greatest certainty, there are similar companies in many other countries.

 

[DanielT]

This is my contribution to this thread with my "pre electric" audio equipment.
The radio is made 1926 in Motala by the Luxor company.
The record player have no brand name but must be from the same time as the radio.

A time in Swedish history where electricity not where common in homes.
But the need for news and entertainment was the same as today.

View attachment 164159
View attachment 164160
View attachment 164161

Nice!

Maybe you, like me, know those who live in Motala? Feel free to send a PM if there is something Luxor related you are looking for.
Du känner kanske Kjell K? Han kan Luxor utan och innan.

 

[DanielT]

Okay now I came up with a question!
When was it possible to create transistor-based amplifiers with lower distortion than tube amplifiers?

 

[Cbdb2]

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.

So what specs are these and why are they only important for audio? And adding a diode (I can glue one on) for temp tracking dosnt really count.

I get that audio devices may have been the reason to design these transistors but do you think they wernt thinking about other uses. A better transistor is a better transistor.
From the data sheet.
"MJW3281A and MJW1302A are PowerBase power transistors for high power audio, disk head positioners and other linear applications."

 

[audio2design]

Okay now I came up with a question!
When was it possible to create transistor-based amplifiers with lower distortion than tube amplifiers?

Never and always You would have to define a power level. Most of the distortion in tube amps is from insufficient gain/feedback and/or transformers in the audio path. Its more relevant to look at distortion + noise.

 

[audio2design]

So what specs are these and why are they only important for audio? And adding a diode (I can glue one on) for temp tracking dosnt really count.

Actually it does, because you can only glue one on the exterior, not on die, and it is specifically for Class AB biasing. Ditto matched pairs. Ditto specific gain/voltage/current characteristics, etc.

It is no different from today. I.E. there are many parts designed for specific markets / applications and those parts would not exist without those markets / applications. It does not mean they will never be used elsewhere.

 

[DanielT]

Never and always You would have to define a power level. Most of the distortion in tube amps is from insufficient gain/feedback and/or transformers in the audio path. Its more relevant to look at distortion + noise.

Ok. distortion + noise...At:

5 W
10 W
20W
40 W

 

[tomtoo]

This is my contribution to this thread with my "pre electric" audio equipment.
The radio is made 1926 in Motala by the Luxor company.
The record player have no brand name but must be from the same time as the radio.

A time in Swedish history where electricity not where common in homes.
But the need for news and entertainment was the same as today.

Ultra cool!!!

Receiver and TT.

 

[TrevC]

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).

I was always delighted when I found one in an amplifier. Made servicing a breeze! In any case I think you are being overly critical. There's nothing wrong with the performance of the higher powered STKs.

 

[TrevC]

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

Nothing wrong with them at all in my experience.

 

[restorer-john]

Nothing wrong with them at all in my experience.

Sure, for mainstream "HiFi" rack system amplifiers, they worked OK. For serious high fidelity amplifiers? No way. Never even in contention.

Sanyo thick film hybrids (STKs) ushered in a whole era of sh#t quality audio. I should know, I spent years fixing their f#%k ups.

 

[ZolaIII]

Guys STK is/whose example of getting the same design working on it from not really good to good enough and really good if not great.

 

[Doodski]

Nothing wrong with them at all in my experience.

I associate STK's with many repairs and that sometimes included repairing a PCB because the cheapness of the gear was such that the PCB traces would lift off the PCB or the unit had been repaired previously and the unit was in for another repair. STK gear is generally junky gear.

I also did a blind sound test in a sound room with a STK driven Sony receiver compared to a Yamaha with discreet transistor circuitry and the difference was clearly audible. The Yamaha was much better sounding and the Sony was not 4 Ohm rated.

 

[EJ3]

Guys STK is/whose example of getting the same design working on it from not really good to good enough and really good if not great.

But it seems that there were more of the not really good (or bad implementations) used, giving them a lesser reputation. Perhaps many were used outside of their ventilation hysteresis (either a manufacturing error or a failure of the owners manual to stipulate that adequate ventilation was needed.

 

[ZolaIII]

But it seems that there were more of the not really good (or bad implementations) used, giving them a lesser reputation. Perhaps many were used outside of their ventilation hysteresis (either a manufacturing error or a failure of the owners manual to stipulate that adequate ventilation was needed.

For example;
STK8280II 80W @ 8 Ohm's THD 0.005
And there is a bunch of them with 0.004~0.005 THD (that are best performing one's).
Source: 5000-IC-Power-Audio-Amplifiers (good book, where you can also find schematics [free in pdf]).