Best BJT's in the world.

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Sorry but there is no such thing as the 'best' transistor.

Each part of a pre-amplifier circuit requires transistors suited
to that sub-circuit, getting the the correct type of transistor
for the application is far more important than the actual
transistor used.

You need several 'types' of transistor for pre-amplifier circuits.

If you have the correct type of transistor from a reputable maker
you won't go far wrong. As far as I know no-one has ever claimed
btween the reputable manafactures a particular makers transistor
of a particular type sounds any different to another makers.

Looking at various quality pre-amp designs will quickly identify
the 'usual suspects' to be used in each circuit position.

I'll just add the quality of the circuit design IMO is the
basic feature that determines the sonic characteristics.

:) /sreten.
 
sreten said:
Sorry but there is no such thing as the 'best' transistor.

Each part of a pre-amplifier circuit requires transistors suited
to that sub-circuit, getting the the correct type of transistor
for the application is far more important than the actual
transistor used.

...

I'll just add the quality of the circuit design IMO is the
basic feature that determines the sonic characteristics.


There is sonic difference between transistors - there really is! In several cases there are alot of types that fits well within an application - and at least I don't know how to tell from the datasheets if for instance the bcx56 i sonically better than the bc850. I believe you have to sit down and listen to them, just as if you were to choose an opamp. Correct me if I'm wrong.

Ofcause the quality of the circuit design is very important, but transistors have some influence too! :)

/Asbjørn
 
Hi Asbjorn .......

The actual transistors do matter if the choice of a
type are not direct equivalents of each other.

Then one particular transistor may suit the circuit
better than another, but only in that particular
application IMO. It is not a 'better' transistor than
the others IMO, just better suited in this case.

I did mention reputable makers - because IMO
cheap transistors are absolutely a false economy.

I'd love to see some-one try a build a circuit and
select the the transistors ONLY by listening tests,
would be very amusing.

How do you know that the circuit with a changed
resistor value wouldn't sound better with all the
transistors you've tried - compared to the transistor
you've 'selected' ?

It all gets very silly, very quickly IMO.

:) /sreten.
 
Re: Hi Asbjorn .......

sreten said:
How do you know that the circuit with a changed
resistor value wouldn't sound better with all the
transistors you've tried - compared to the transistor
you've 'selected' ?

Well, within some "limits" a transistor sounds reasonable the same. In practice for instance a transistor without good bass reproduction never gets this just by replacing some resistors. I mean - yes - a transistor sounds different when used with different resistors, but within some "limits" you really are able to hear whether a transistor has some sonic capabilities or not!
 
I agree with sreten. The "best" transistor is no good if your circuit design isn't good. And if your circuit design is good, you will probably find that a wide range of transistors work well in it.

Transistors themselves don't actually have "good" or "not good" bass reproduction--that's a function of the circuit design, too.
 
AudioBob said:
I agree with sreten. The "best" transistor is no good if your circuit design isn't good. And if your circuit design is good, you will probably find that a wide range of transistors work well in it.

Transistors themselves don't actually have "good" or "not good" bass reproduction--that's a function of the circuit design, too.

That's simply not true. based on countless listening tests I can say for sure that transistors really have a sound of their own (again within som limits)! :smash:
 
AudioBob said:
I agree with sreten. The "best" transistor is no good if your circuit design isn't good. And if your circuit design is good, you will probably find that a wide range of transistors work well in it.

Transistors themselves don't actually have "good" or "not good" bass reproduction--that's a function of the circuit design, too.


Don't quite agree with this :). if your design is good then you
should know what transistor parameters are important for the
transistors in each application.
Often your choice of transistor is surprisingly limited.

I keep mentioning 'reputable' manafacturers. Even they have
transistors that look good on paper but can exhibit parasitic
effects in some applications - which you obviously don't want.

Re Asbjorn :

If your willing to say this about transistors with near identical
parameters, similar construction and quality control fair enough.

Personally think there must be some real differences between
the transistors you are talking about.

:) /sreten.
 
Asbjorn said:


That's simply not true. based on countless listening tests I can say for sure that transistors really have a sound of their own (again within som limits)! :smash:

After more countless listening and bench tests, I can say for sure that I disagree with your conclusion. Transistors do not have good or bad "bass reproduction." If anything, lower frequencies are less problematic for transistors.
 
AudioBob said:


After more countless listening and bench tests, I can say for sure that I disagree with your conclusion. Transistors do not have good or bad "bass reproduction." If anything, lower frequencies are less problematic for transistors.

Well okay, please explain, and give me some examples based on one of those countless listening tests. :)
 
sreten said:

Don't quite agree with this :). if your design is good then you
should know what transistor parameters are important for the
transistors in each application.
Often your choice of transistor is surprisingly limited.

I guess I shouldn't have said "wide." ;)

But I've yet to be involved in a non-high-power design where only one specific brand and device qualified. It's not difficult to design a reasonable degree of invariance into a circuit.
 
sreten said:

If your willing to say this about transistors with near identical
parameters, similar construction and quality control fair enough.

Personally think there must be some real differences between
the transistors you are talking about.

:) /sreten.

Agree, but I think it is hard to tell from small differences in for instance a datasheet what transistor sounds the best. Which parameters is important for sound quality and which is not? :xeye:
 
Transistors

I'm not going to contradict you as I have tried several transistor types in headphone amps and found audible differences, but they also had different characteristics.

For instance I tried BF469 and BD139 as a VAS-Buffer in an amp and prefered BD139, although the difference was small. But in this case, their Beta is quite different, which should probably explain is (ie. in this position, a transistor with a higher Beta would work better)...

Can you sate more precisely which types you compared and in which position ? Did they have differing characteristics or not ? And most important, what did you hear ?

I believe everything is important, from the well documented data (Beta, Ft...) to the obscure ones (like chip size, thermal characteristics, variation of Cbc and Cbe with Voltages...)

Mind sharing your results ?
Thanks...


Asbjorn said:


There is sonic difference between transistors - there really is!

/Asbjørn
 
Transistor sound

The characteristic sound of an amplifier (or CD player for that matter), is based on the harmonic distortion. The statement that there is a transistor with "good sound" is both true and false, actually 99% false.

The human ear percepts third harmonc distortion as a "foul" sound, the second harmonic however makes the amplifier sound "warm". Tube amplifiers have very large second harmonic distortion (often1-10%), thats`why they have a "warm and soft" sound.

You could go the effort and tracking down transistors that are expensive, and are used in Krell, Electrocompianet and so on, but the results will be minute.
There are many more and better ways to make your amp sound the way you like, just remember that third (odd harmonics generally) has an ugly and harsh sound.
You could with a little effort design an amplifier in the 0.001% THD region with general purpose transistors (BC546, BD139, TIP35), and make it sound like a million!!
The key is using good constant current source and an active mirror load at the differential input (if you want a warmer sounding amplifier, just replace the current mirror with resistors, this will increase the second harmonics).

OK, a lot of talk here...the bottom line is, its the circuit topology that desides the THD and S/N. I a wilson current source would make a differental input pair consisting of BC546/BC556 transistors sound far better than replasinbg the wilson with a Transistor-diode current source and using 2SC2240 transistors (however I would use the 2SC2240/2SA970 anyway because they have higher Vce tolerances, and they have higher beta (a wilson curren source with that also uses these, will have an output impedance in the 10-50Mohm region).
 
PanzerLord: A lot of theory unwrapped in an easy to understand and logical explanation. Better that you just said it, it can't be said!

However there is one small addition, that some transistors have higher collector leakage than others, causing them to add more to the distorsion of the stage. Also i always look at the hfe linearity of the transistor, because if it is used over a wide delta current span, you can risk the load the base of one transistor causes on the previous stage to add an extra distorsion component to the formula. If you stick to hfe linear devices (like the 2SC2240) you don't have to take this factor into consideration.

But still you are right BC546 can go a long way! For you americans that would be a 2N2222. :)
 
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Re: Transistor sound

PanzerLord said:
The human ear percepts third harmonc distortion as a "foul" sound, the second harmonic however makes the amplifier sound "warm".


I have seen some articles, and empritical tests that cast doubt on that "conventional wisdom": according those papers, human ears are actually quite inept at distinguishing odd and even harmonics.

wish I could remember where I read them.
 
Harmonic distortion

With all due respect, harmonic distortion is ********...

While I agree with what you said about the sound of harmonic distortion (that an amp with a lot of odd order distortion will sound bad (as you said) and an amp with second order distortion will sound less bad (but still not perfect)), a lot of the amps which measure .001% distortion sound absolutely wretched...

I don't endorse saying that "distortion does not matter" ie. I think a good sounding amp must have low harmonic distortion, but it does not work the other way, ie. an amp with low harmonic distortion does not necessarily sound good. As evidenced by the many consumer grade gear around, which sounds like ****.

Measurements are meaningless if they don't correlate with what we hear. It seems that after all these years, researchers finally found something :

http://www.gedlee.com/distortion_perception.htm

Read this article, play the sound files, look at the THD measurements, and tell me, would you prefer the one with the lowest THD really ?

Good evening !
 
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