Pass amp with 2n3773?

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S

Stocker

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Joined 2004
oh come now, if he builds it and it sounds bad

...and complains about it here...

he will be roundly condemned for having used those transistors,
pestered until he changes them and admits their sound charicteristics
or goes away.

Let's be honest about the nature of the community @ DIYAudio!
 
Greg Erskine

Greg Erskine

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Joined 2002
Paid Member
Hi Tassy,

I had a bag of RCA 2N3773, probably 20 years old, and just wanted to do something with them too. I just finished building a little JLH class A thing last week and my initial impressions are good. :D

Now I don't know which Pass amp would suit, if any, but if you are planning on a large (i.e. costly) project it doesn't make sense to risk the outcome by using ancient components. :bawling:

If you want any details on non-Pass amps please PM me.
 
djk

djk

R.I.P
Joined 2001
Don't let these guys give you a hard time.

If you notice, Motorola (On Semiconductor) uses the same set of transistor curves for the MJ15024/25 which Nelson Pass used in some of the newer Threshold designs.

At 100V the 2N3773 has higher SOA than the MJ15024.

For a sub amp you should be fine.
 
tiefbassuebertr

tiefbassuebertr

Member
Joined 2005
tiefbassuebertragung.de
djk said:
Don't let these guys give you a hard time.
If you notice, Motorola (On Semiconductor) uses the same set of transistor curves for the MJ15024/25 which Nelson Pass used in some of the newer Threshold designs.
At 100V the 2N3773 has higher SOA than the MJ15024.
For a sub amp you should be fine.
Click to expand...
Interesting observation. Unfortunately there are four different brands, which currently offer this type - go to
2N3773 Datasheet pdf - Power 16A 140V Discrete NPN - ON Semiconductor
in early days this type was also produced from RCA and Toshiba.
From which brand is your 2N3773 device with higher SOA than the MJ15024 ?
markp said:
Why would you want to use that old transistor? Almost any newer design will be better. Its like using a 741 IC in a modern preamp!
Click to expand...
for two weeks I have get for service an older diy amp project from 1978 with 741 as front end and 2N3773 in quasi complementary super beta follower with 50mA idle current through the output stage. Sonic quality wasn't below of currently topologies with modern components by same values of idle current. This means, if no hard running mode (i. e. class-A) is in use, the theoretical advantages and advantages by measurement of modern devices (like LME op-amps and high ft transistors, e. g. from Sanken) provides not a clearly audible enhancement in sound quality, at the most a changing in sonic character.
 
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djk

djk

R.I.P
Joined 2001
"From which brand is your 2N3773 device with higher SOA than the MJ15024 ?"

All of them have higher Isb than the MJ15024 at 100V (Wingshing doesn't list that spec), but it's required in order to be called a 2N3773.

http://www.onsemi.com/pub_link/Collateral/MJ15022-D.PDF

As we can see, the MJ15024 is only rated at 100W at 100V, and any of the 2N3773 sheets you linked to show 150W at 100V.

Now if you're talking 80V, the MJ15024 is rated at 160W vs only 150W for the 2N3773.
 
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