What about so called audio output transistors ?

Hello !
I've heard some Luxman nerds stating that a Luxman amp had been tampered with because the output transistors where not the Luxman one but Toshiba's (with the very same part number, but labeled Toshiba instead of Lux... ).
BTW, I did not know that Luxman was a silicon founder ....
I've an amp which failed and the output transistors were shot. They were 2SD716/2SB686 which are not made anymore. I replaced them with the ubiquitous TIP35C/TIP36C, but the original state on their fiche that they where devised for audio applications.
So what is special about them ? Have I ruined my amp by not putting "audio" transistors in it ? Should I mourn the loss of this amplifier or could I use it and enjoy the music ?
I'm puzzled, so all advice will be listened and followed !
Have a nice day !
 

academia50

Member
2013-01-16 2:52 pm
Yes, but problem is that the original transistors had no maker identifiable and i do not trust Chinese datasheet values. They are not worth the paper they are written on.
As I had some TIP35/36 in my drawer, I _admit_ I did not think twice before soldering them. And the amplifier runs fine since (I do not know if the output power is the same as before (well it is better because it was zero with the failed trans...) ) but I'm happy with it !
I'll search for my bottle of snake oil and dip the transistors in it to get better sound. I had plunged them in holly water but obviously it was not enough....
Have a nice day !
 

academia50

Member
2013-01-16 2:52 pm
In last instance, testing it with audio material, will tell you if the amp is better or worse than with original parts.

But that is only possible if only one channel failed and the other is OK.

The OP does not clarify that ....
Anyway, I wouldn't trust a hearing test.




Pero eso solo es posible si falló solamente un canal y el otro está OK.

El OP no aclara eso ....

De todas formas, yo no confiaria en una prueba auditiva.
 
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luxman nerds?

You should beware when "Luxman nerds" are so vague about what might be better about the original parts. Sounds like they have no clue about transistor parameters. And remember that the original parts failed so how good were they? It's been years since I repaired professional amps but back them I rarely used the original parts, because amp makers are using the cheapest thing they can and a year later there is always a better part for less money.

I know that TIP35/36 are great for high currents. The only possible issue might be speed.
 
I've heard some Luxman nerds

I know nothing about Luxman nerds, but the Krell nerds advise against replacing the outputs with Motorolas. And for a good reason.

It is not impossible the Luxman transistors have a tighter match for Hfe than random batches from Toshiba.

As for replacing 2SD716/2SB686 with TIP and believing nothing has changed...the only conclusion i can draw is you don't really listen to your amps.
 
"As for replacing 2SD716/2SB686 with TIP and believing nothing has changed...the only conclusion i can draw is you don't really listen to your amps. "
I didn't say that. I just said that it works and is about as powerful as it should. As I could not find the correct part (except from ... China .... ) and as I had these, I put them in. But I'm well prepared to put better ones if you can spec them. (and I can find them easily)
 

wg_ski

Member
2007-10-10 5:21 pm
Looking at the data sheet I saw nothing special about the original parts, other than they were 60 watt devices. Back in the day they were probably cheaper than the typical 130 to 150 watt TO-3P’s. Any of the typical “audio amp application” TO-3P devices is probably better than the TIPs, which are generic and have very loose specs. They vary greatly from one batch to another. Even amongst real ones (ST uses more than one fab, and you get something different from them that meet the loose spec. ON may do the same, but I don’t have units with different origin codes to verify like I do the ST’s). The amp obviously works with the TIPs, but if you wanted something more like the originals, which ones to use? The answer is what can you get without risk of fakes, Sanken, Toshiba, ON semi? You can get comparable parts from any of them, if you don’t need the last ounce of speed or ruggedness. Nothing about the original suggests that you do. Would it sound any better? No idea. That really does depend on the amp design - and how much snake (or CBD) oil you’ve been ingesting. Would it measure better? Probably.
 
;Thank you for your help !
As I plan to use the amplifier for a long time, I've ordered 4 Sanken 2SC4467 / 2SA1694 because I had to order some other parts. These helped get free shipping ...
I'm not listening to my amplifier. I listen to the music. Actually, right now I'm listening to a mono record of an opera ... ;) Who said that I'm not an audiophile ? :D
 
No,
The marriage of Figaro on an RCA red seal "Selected by the Metropolitan"...

Very good, it reminds me of the promotions of Selections of the Reader Digest ...... I still have "Popular Music that will live forever" ....... they were monophonic editions of very poor fidelity, but they were promoted with bombastic names ....
But they fulfilled the function of making people know different genres of music.

https://articulo.mercadolibre.com.a...cking_id=d19c7319-21d8-4fae-bc1c-5d510eb1349d



"Cyclophonic" sound! Wow, the sound is insufferable, it does not even come close to the 78 RPM pasta discs, of which I still have some inherited ones, mine were lost and / or broken in successive removals.

I especially remember a 78 RPM pasta album that I listened to until I was tired, it was a pleasant surprise to find those songs on YT:
Giacomo Rondinella, obviously you know him.
Core I´ngrato and Adormendarme Cosí.
Here it is :

YouTube


YouTube

Enjoy and salutti, amicci ! :)
 
Did you readjust the output transistor bias after replacing them? It probably needs doing, and might make a big difference.

If you choose the transistor with the correct gain (Hfe equal to the original) I suppose it will not be necessary.
Note that you must open the circuit to measure the IC current, which is a delicate task on PCBs
Only my two cents