That was exactly my problem. Tight matching in the same type but poor matching between NPN and PNP. These were Diotec from SOS Electronic, 4000 purchased (I thought they will be enough) with a difference of approx 70 between the averages. Ended up with 2000 more (CDIL, Fairchild, NOS ITT, and NOS Siemens) sourced from various suppliers... Measured several times each, until I built the fixture with the fan blower, and final matches were done at the same temperature.
I must admit, this was the Hell out of Paradise build , but you must have both or nothing
Measured several times each, until I built the fixture with the fan blower, and final matches were done at the same temperature.
I must admit, this was the Hell out of Paradise build , but you must have both or nothing
Yes Hell but is worth the efort (I can promise you this)
I was doing most of the measuring in a cold loft with a lamp to keep the litle critters warm and a termometer to mesure the temperature near by
So how warm is the air you blowing then? and in the morning?
There is going to be same difference no mather what. just mesure the 3000 and sort then sort with finer match and then again and again
Funny....I still have the gigles as at the begining some one was making acusation that the GB transistors where pre sorted so it was not possible to get PNP and NPN match
Just to clairfy.
I will send small numbers of transistors out where people tell me exactly what value and how many they need. I won't send out 36 to one person, but i will help you finish your matching.
Some measurements from my last boards. All shunt outputs set to 18.5 volts.
Left channel
Op-amp pin 6 1.2v, (wanders 5mv)
Riaa 400mv wanders 50mv+/-
Vcascl 15.10v
Vcasch 15.11v
Input offset 0.0
Right channel
Op-amp pin 6 1.25v, (wanders 5mv)
Riaa 400mv wanders 50mv+/-
Vcascl 15.12v
Vcasch 15.09v
Input offset 0.0v
The matching on these voltages is at least 10x better than my first build- and my first build sounded great.
I will send small numbers of transistors out where people tell me exactly what value and how many they need. I won't send out 36 to one person, but i will help you finish your matching.
Some measurements from my last boards. All shunt outputs set to 18.5 volts.
Left channel
Op-amp pin 6 1.2v, (wanders 5mv)
Riaa 400mv wanders 50mv+/-
Vcascl 15.10v
Vcasch 15.11v
Input offset 0.0
Right channel
Op-amp pin 6 1.25v, (wanders 5mv)
Riaa 400mv wanders 50mv+/-
Vcascl 15.12v
Vcasch 15.09v
Input offset 0.0v
The matching on these voltages is at least 10x better than my first build- and my first build sounded great.
For every one, always get your transistors on a strip (never get loose one's). This will prevent them being 'cherry picked' (but other problem may still exist).
[Theory] Law of Conservation of Problems. - The PokéCommunity Forums
These measurement look good, very good, exceptionally good, amazing!
You have a (almost) 1% match between the channels, nice!
Thanks Fdw, I did match them from over 2k transistors. I think I probably spent 20+ hours just matching.
Here's the temporary loading arrangement.
An externally hosted image should be here but it was not working when we last tested it.
Here's the temporary loading arrangement.
The day-shelter may require corner panels, to prevent side-draft effects.
(Frans, the EO rule-book clearly forbids it to become too hot. https://www.youtube.com/watch?v=-5EmnQp3V48 )
Could we have a better substitute for this pair of PNP and NPN transsitors to ease matching.
I found the 2SA970 and 2SC2240 matched easily.
Hfe classification for 2SA970 and 2SC2240
GR:200-400
BL:350-700
I haven`t tried on this circuit for compatibility.
Beside having difference pins out, they do have difference electrical parameters.
I am afraid a direct substitute without altering the values of other components would work.
GR:200-400
BL:350-700
I haven`t tried on this circuit for compatibility.
Beside having difference pins out, they do have difference electrical parameters.
I am afraid a direct substitute without altering the values of other components would work.
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This ones and the complement work too and they are still available although not made any more :
http://www.toshiba.com/taec/components2/Datasheet_Sync/50/6455.pdf
again they have another footprint
http://www.toshiba.com/taec/components2/Datasheet_Sync/50/6455.pdf
again they have another footprint
All, please note the updated documents in my signature. No big changes, only small fixes so do not worry
Q107/207 still shows J310 (should be J113 and Rgs 1K)
when time is available, please fix this