Sonic impact of NPN outputs?

[Artie]

File this under corona miscellaneous ramblings.

I have both a Kenwood KA-400 and KA-500 integrated amp. Both are circa 1980 and both are close to the same power. 43W vs 45W. The KA-500 is a bit of an oddball. It was part of a remote control system, before they really had remote control down pat. So it uses a standard volume pot, connected to an electric motor, through a "dial-string" type setup.

The KA-400 uses the conventional NPN/PNP output configuration. The KA-500 uses twin NPN's. I know that in the early days of SS they had difficulty making higher power PNP's. But I think 1980 was well past that time. (KA-400 as an example.) So, I'm curious, is there any sonic impact to the NPN/NPN output configuration? Any electrical disadvantages?

 

[tarior]

There are plenty of quasi-complimentary push-pull amplifiers out there that are well regarded for sound quality. If it sounds good (to you), then it is good.

 

[dlucy]

You're talking about the difference between a fully complementary (NPN + PNP) and a quasi-complementary (NPN + NPN) topology or design.

There are a bunch of articles on this:

https://audiokarma.org/forums/index.php?threads/quasi-or-fully-complimentary.110105/

https://www.diyaudio.com/forums/solid-state/162310-identify-quasi-complementary-amplifier.html

https://ampslab.com/c200qc.htm

https://www.diyaudio.com/forums/sol...sfets-nmos-audio-complements-audio-power.html

https://www.diyaudio.com/forums/solid-state/94030-quasi-quasi-question.html​

 

[Guest159]

Outputs are followers and they should color the sound very little. I don't even bother matching the output MOSFETs in my F5, and when replaced a pair in my left channel I literally just pulled the parts out of the bags and soldered them in. The N and P channel parts aren't even from the same manufacturer. I can't hear any difference between those parts and the originals in the right channel. Push-pull output stages don't require parts to be matched unless something about the bias circuit calls for it. Two different parts working against each other will tend to mitigate their differences and produce low even order distortion. I can't see how complimentary should have any particular advantage over quasi-conplimentary except it allows for a simpler design and fewer parts.

 

[Artie]

There are a bunch of articles on this:

Great links. Thanks. The Ampslab link is the one I was reading that got me thinking about this.

Edit: That's funny. I actually commented about my KA-500 in that first link, and forgot all about it.

 

[leesonic]

There is also the cap-coupled version to consider. The types that use two NPN outputs across a single supply rail, and use a capacitor on the output to block the DC. Logic would suggest that another component in the output would worsen the sound, but it doesn't. I've had a few Pioneer SX-626 receivers which are cap coupled, and sound sweet.

That KA-400 looks good, I remember those when they came out.

 

[Artie]

That KA-400 looks good, I remember those when they came out.

I have the matching tuner also. But I had a little accident with it. The cord got wrapped in my legs while I was carrying a turntable, and I yanked it right off the shelf. It smashed one of the corners, which is plastic. I still kick myself today for not being more careful.