Good list will use it for my next one

Hi Søren,

I look forward to your “next one” with great anticipation. No surprise there.

I also look forward to your excellent progress photos which alone are worth the “price of admission.” 🤒

Jeff

About the transistors,

The SE6002 you replaced with BC550

The BC154 you replaced with BC560

How about the BC109 and the SE8002?

And again, thank your for the most valuable thread! 

You are stretching my memory capability (old brain)

I changed all the NPN and PNP transistors looking like a black drop

NPN: BC 115, SE 6002, UW 0029 = BC 550B, B is low noise TR

PNP: BC 154 = BC 560B

I didnt change any BC 109 or SE 8002

Well, the last B does not indicate noise level but HFe range;

BC550A (low HFe range)
BC550B (medium HFe range)
BC550C (high HFe range)
All other parameters are basically the same.

Regarding noise-levels:
BC107, BC108, BC109 are in reverse order of noise-level. (They will also have the last A,B or C attached for HFe range identification).
Same goes for BC546, BC547, BC548, BC549, BC550 - largely speaking.

SE8002 can be replaced by BC141
BC109 can be replaced by BC550

When replacing the "vintage" transistor types, I like to use HFe range B transistors.
Using C's instead will not necessarily improve anything.

Martin

Right Martin, I am mixing things up from memory, BC 550 has the lowest noise level of the before mentioned and is medium range HFe

Thank You!

BC109 is the same as UW0029. 

So:

NPN: BC109, BC 115, SE 6002, UW 0029 = BC 550B     ;     SE 8002 = BC141

PNP: BC 154 = BC 560B

I used BC550CTA and BC560CTA because that was the closest match I could find.

Well, I don't like the = sign.
Perhaps we could just say, that they will work as replacements for eachother in this amplifier.

Martin

A couple more thoughts;

The BCxxxCTA transistors...
The last TA I seem to remember just stating, that the component is put on tape/ammo-belt (for machine mounting).
It's not important for the circuit.

The C however, is the HFe range identifier (as mentioned above).
When you work with output stage amplifiers with silicon devices - like this one and also complementary types - it's almost
always a good idea to keep things a bit on the "low and slow" side.
Using low-ESR electrolytic capacitors (caps with a very low series resistance), metal-oxide resistors, Schottky-barrier diodes
and transistors with a high current amplification, could up the risk of self-oscillation - one
of the most dangerous situations for an amplifier of this build type.

I've seen so many times, that owners wanting to do the very best to their amplifier put all the
modern, linear and in any way perfect stuff, they can lay their hands on in there.
If all components get "too eager" then the amplifier disappoints with a sterile sound (or runs astray).

No, - keep the "elastics" and their "laziness" in there. It will also help preserve the vintage ("warm") sound.
That's how I like to do it, anyways.

Martin

Dillen wrote:

A couple more thoughts;

The BCxxxCTA transistors...
The last TA I seem to remember just stating, that the component is put on tape/ammo-belt (for machine mounting).
It's not important for the circuit.

The C however, is the HFe range identifier (as mentioned above).
When you work with output stage amplifiers with silicon devices - like this one and also complementary types - it's almost
always a good idea to keep things a bit on the "low and slow" side.
Using low-ESR electrolytic capacitors (caps with a very low series resistance), metal-oxide resistors, Schottky-barrier diodes
and transistors with a high current amplification, could up the risk of self-oscillation - one
of the most dangerous situations for an amplifier of this build type.

I've seen so many times, that owners wanting to do the very best to their amplifier put all the
modern, linear and in any way perfect stuff, they can lay their hands on in there.
If all components get "too eager" then the amplifier disappoints with a sterile sound (or runs astray).

No, - keep the "elastics" and their "laziness" in there. It will also help preserve the vintage ("warm") sound.
That's how I like to do it, anyways.

Martin

I have been reading Martins opinion here and ...................................

I could not agree more, all Martin's points is correct and really like we should handle the restoration of these fantastic classic products.

A small note to "underline" my statement,

I have been working for Bang a& Olufsen for more than 25 years and 6 or 7 years I was working in the development department responsible for the components approved for use in the products.

Martins statement was really the target for the components choise and what we approved to be accepted for the development engineers to use in new designs.

/Frede