D.Self's diag omits Q4 Re = 0r5
70r shows higher levels of 7th and 9th
Yet lower and higher resistance brings these back to adjacent harmonic levels????
Although 40r looks worse than 100r
Could 120r and 150r tell you anything?
70r shows higher levels of 7th and 9th
Yet lower and higher resistance brings these back to adjacent harmonic levels????
Although 40r looks worse than 100r
Could 120r and 150r tell you anything?
Yes, I messed up the connection of the transdiode
Sadly when I connected it right the result is not that good as before. I get at most the same amplitude of 2nd and 3rd harmonics at about 70R. Lower or higher the 2nd lower and 3rd rise pretty much.
I used a PNP as I've seen in the book of Douglas Self. I attached a screenshot of the schematic he presented. I don't see a 0.5R resistor added in series, but maybe a more detailed implementation could include it. I'm not that knowledgeable as to assert anything.
JLH gives the connections as follows:
Attachments
That would mess with the physical layout too much. My approach is much less intrusive. Plus, I'd have to use power diodes to support the current.
And also I don't know how that couples with the fact that the output transistor's emitter resistor is bypassed by a power diode.
And also I don't know how that couples with the fact that the output transistor's emitter resistor is bypassed by a power diode.
The top picture shows the scheme used by 'Shaw' in an article in WW.
The bottom left picture is the mod suggested by JPB in a letter subsequently.
The bottom right picture is the scheme used by JLLH for his 70 watt amp.
The pictures are given by JLLH in a subsequent series on Audio Amps in WW.
With Re=0R5 for the transdiode I don't see much happening.
Left picture is without and right with...
Measurements with driver Re = 70R at 1W output into 6 ohms.
Attachments
- Status
- Not open for further replies.