Post some only NPN amplifier, please.
It can be phono RIAA or preamps or headphone amps or power amps.
I start with this power amplifier I have designed.
It puts out 10 Watt and works in Class A push pull.
The distortion at 1 Watt is only THD 0.00009% according to SPICE.
It can be phono RIAA or preamps or headphone amps or power amps.
I start with this power amplifier I have designed.
It puts out 10 Watt and works in Class A push pull.
The distortion at 1 Watt is only THD 0.00009% according to SPICE.
Here is one of the few power amplifiers I found.
With only NPN transistors. Sony TA-1010.
It is actually similar to my amp I posted.
With only NPN transistors. Sony TA-1010.
It is actually similar to my amp I posted.
Actually NOT that similar. That Sony is internally capacitively coupled and class B (AB). The topology works quite well in class A, not so much in B.
Here is a simple headphone amp that performs pretty well actually. Distortion is essentially independent of frequency.
Yeah, I expect that design has been around a long time. I recently have been playing with portable HP amps that are similar but class-AB output (of course) and a JFET input - mostly as an exercise to learn something about JFETs. Tubes look like a lot of fun, but I know I am too clumsy to work with high voltages.
Im too clumsy to work with modern SMD. I simply wont design around fine pitch (0.5 mm) ICs or anything BGA. At work, yeah, but I’m not the one assembling it. And having the board house stuff your board isn‘t really DIY anymore. All my solid state work is either vintage topologies or kilowatts. The middle has been conquered - really nothing (for me) to be gained or learned. My favorite vintage all NPN SS power amp circuit uses a ….. Noooooo - don’t say the T word!………
I have the original Nelson Pass 20W class A - the one using six 2N5878 (I used 2N3772) in the output stage. Single ended class A. But it does use PNPs elsewhere.
I have the original Nelson Pass 20W class A - the one using six 2N5878 (I used 2N3772) in the output stage. Single ended class A. But it does use PNPs elsewhere.
This is a headphone amplifiier with Gain=2 with 3 NPN transistors.
It works in Class A with a regulated supply 24V.
Low distortion.
It works in Class A with a regulated supply 24V.
Low distortion.
lineup - I remember having a receiver and a tape recorder that both used a push-pull output stage driven by a transformer for phase inversion. All transistors were NPN. I believe this was a common arrangement before complementary circuits took over.
Ed
Ed
During the golden japanese semiconductor era in 70s and 80s, the SC companies in Japan (Sanken, Toshiba, Hitachi, Sony, Sanyo, etc.) designed complementary pairs especially for audio and all they were with equalised parameters. I mean NPN and PNP with almost identical characteristics. I.e. they intentionally worsened NPNs and enhanced PNPs to achieve such a result. The negative feedback is the main problem for solid state amps, not PNPs.
There is an older thread on NPN only amps... found it 🙂
I always remember the Sony TA1010. Circuit and LT file in the thread.
https://www.diyaudio.com/community/...ly-1-type-of-transistors.354589/#post-6207406
I always remember the Sony TA1010. Circuit and LT file in the thread.
https://www.diyaudio.com/community/...ly-1-type-of-transistors.354589/#post-6207406
Had also transformer driven transistor stuff like this, but long before there was any npn in sigth and ft was still far from anything worth stating in megacycles
I had the original Phase Linear model 700, and that used NPN transistors (TV horizontal driver ones) for outputs in a quasi-complementary arrangement, and I think the small signal ones were all NPN as well. It was hard to find PNP types that could handle the amp's +/- 100V rail voltages at the time.
I found the receiver schematic! It used transformer drive as I remembered but with germanium PNPs.
Ed
The original PL700 still used a PNP predriver on the negative side. Almost impossible to design out of anything that big. Newer ones also had one small signal PNP between the op amp and VAS, and another in the negative current limiter (not that they helped much). None of the original output types, all derivatives of the Delco DTS410, were really rugged enough for the 400, let alone the 700. IMO, it was never safe to use until the MJ15024 came along. I found one where the outputs had been replaced with 2SD555, which was as good a Jap unit as you were going to get for a 700. Better choices available for the 400 where a 200 V-capable part was good enough (didn’t need to go to 250). The most rugged Jap transistor ever made, the 2SD424, simply could NOT be used one volt over 200 so they were out for use in a 700. And these amps worked soooooo much better if you changed them to full complementary, where class AB bias could be safely used. That takes MJ15025’s.
That old transformer-drive circuit was originally for PNP Germaniums. All the good power stuff was PNP and it was everywhere. That old circuit placed a negative base bias on the “off” side - which allowed you to run up to Vcbo. Which was often much higher than Vceo on Ge parts. On original 2N3055’s too - another reason transformer drive worked well with them. Those old circuits, operating on 80 volt supplies, tended to be more rugged with the transformer drive than with the newer QC circuits. Which is why makers like Peavey stuck with them for so long. Eventually, transformers got more expensive than PNP silicon, and they finally died off.
That old transformer-drive circuit was originally for PNP Germaniums. All the good power stuff was PNP and it was everywhere. That old circuit placed a negative base bias on the “off” side - which allowed you to run up to Vcbo. Which was often much higher than Vceo on Ge parts. On original 2N3055’s too - another reason transformer drive worked well with them. Those old circuits, operating on 80 volt supplies, tended to be more rugged with the transformer drive than with the newer QC circuits. Which is why makers like Peavey stuck with them for so long. Eventually, transformers got more expensive than PNP silicon, and they finally died off.
Hammond wants more than 20 bucks for one of those little split secondary transformers these days. And the models they have now can NOT be used in single ended drive mode where DC bias runs thru the primary. Not enough gap, and they saturate at about 4 mA DC. Those old drive circuits needed 20 mA or so in the driver stage. They work ok capacitively coupled on the primary - but that’s NOT the old classic circuit!