Hi guru's,
I'm at a position where I can obtain some new and original Sanken output transistors, TO-3P.
I'm wanting them for replacing original TO-3 metal transistors in some of my Sansui amplifiers if needed.
I have successfully used 2SA1693/2SC4466 in a rebuild, they are 20mhz parts, without instability issues.
I wanted the the lowest gain parts, "O"= 50-100 hFE, to be closer to the originals but they only have high gain "Y" = 90-140 hFE.
( O= 50-100, P= 70-140, Y = 90-140)
I'm not educated well enough to fully understand the relationship of the gain when switching out these parts however I still would like to get the parts if higher gain would work as the lower would.
Tia.
Ben
I'm at a position where I can obtain some new and original Sanken output transistors, TO-3P.
I'm wanting them for replacing original TO-3 metal transistors in some of my Sansui amplifiers if needed.
I have successfully used 2SA1693/2SC4466 in a rebuild, they are 20mhz parts, without instability issues.
I wanted the the lowest gain parts, "O"= 50-100 hFE, to be closer to the originals but they only have high gain "Y" = 90-140 hFE.
( O= 50-100, P= 70-140, Y = 90-140)
I'm not educated well enough to fully understand the relationship of the gain when switching out these parts however I still would like to get the parts if higher gain would work as the lower would.
Tia.
Ben
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If it’s a complementary push-pull emitter follower ops then you want the high gain and the pairs to have the same gain or at least the same hfe grouping or grading.
Thank you, rsavas.
These amps use quasi complimentary NPN/NPN and some are Cap coupled.
Others are full complimentary PNP/NPN.
Any other examples why higher gain could be of benefit? Or perhaps a detriment to subbing?
Ty.
These amps use quasi complimentary NPN/NPN and some are Cap coupled.
Others are full complimentary PNP/NPN.
Any other examples why higher gain could be of benefit? Or perhaps a detriment to subbing?
Ty.
Gain in power devices does not move up and down uniformly. There can be a spread of 50 to 140 at 500 mA, but be the same 20 at 10 A. Or at least much closer (say, 22 vs. 20). The lower rank part will therefore have less gain variation across current, and it’s -3dB frequency will be higher. Depending on loading, how many you have in parallel, whether or not you have a 3rd predriver stage, and how flat your driver stage(s) are this may be more valuable than the extra low current gain.
That's why sustained beta devices make the best outputs... Most of them are pretty flat gain all the way to high currents, presumably they pull some tricks to avoid current-crowding and beta-droop..
You guys here a wealth of knowledge, I really only have basic understanding of electronics, which I am content with for now. I do enjoy restoring classic Sansui and vintage speakers to enjoy, so it lends well to an interest in audio electronics.
With what you have explained, I feel more comfortable with not being particular on hFE.
One thing I was concerned about though, would volume increases result in more output to the speaker with higher gain outputs? Or would that remain the same with any gain?
Tia
With what you have explained, I feel more comfortable with not being particular on hFE.
One thing I was concerned about though, would volume increases result in more output to the speaker with higher gain outputs? Or would that remain the same with any gain?
Tia