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@JohnH The book is really useful, in some areas maybe a bit overloaded with math. Some parts of the German version are officially available for free on the web and there is also a nearly complete english version freely available. Re your thoughts on output impedance: As Manfred Z writes it's not...
Thanks for your comprehensive answer. Gauge and switches/jacks is not an issue, e.g. my bypass switch is specified for 125V/15A. I'll give it a try with my tweed bassman and will report the results :) The impedance values I've quoted are from this book (see last page of this chapter, diagram...
@JohnH What are the limitations of your model - will it work to just divide the components values for 8 ohms by 4 to build a 7+3.5 dB version for my Tweed Bassman's 2 ohm tap? I haven't read each and every post in this thread, so I apologize if this has already been discussed...
@JohnH I found some measurements of tube amplifier output impedances in a German book that might be of interest (all for 8 ohms and 1kHz):
AC30 - 70 ohms
Marshall 18W - 90 ohms
Tweed Deluxe - 80 ohms
Super Reverb (w/o NFB) - 180 ohms
Super Reverb (w NFB) - 17 ohms
In the meantime I've built the 7+3.5 dB 16Ohms version for a friend's vintage AC30 and he is happy. And it turned out, that 10.5dB was a bit too much so in the end I've added a switch to bypass the 3.5dB stage ;-)
Hi JohnH,
first of all - great work and thank you very much for sharing and supporting this!
I've built the M version and found, that 7 + 3,5dB ist best for my needs (I don't want to bring down my amps to bedroom level, half volume is great for my needs) and is also very transparent with my NFB...