00940
Headphoneus Supremus
- Joined
- Nov 6, 2002
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Max power was estimated by Dsavitsk at about 750mW, I believe. I would be surprised if some OTL amps exceed that with low-impedance loads, but I suppose if the tubes were very powerful in their own right, it might.
It's not very difficult to calculate. If B+ is about 275Vdc, Va about 200Vdc and the CCS needs about 10V to operate, max positive swing is 65V. Since the edcor has a 10K-32 ratio, it translates into almost a 18:1 voltage ratio. Hence, into a 32r load, max positive swing is 65/18= 3.6. That's about 2.5Vrms. From there, rms power is about 200mW into 32r.
This doesn't take into account DCR losses, so real max power is more like 180mW. Which is way more than most OTL into 32R. To put things in perspective, the optimized Morgan Jones is only 10mW into 32r at clipping.
edit: silly me... power could be directly calculated from the 65V into 10K... but the result is the same.
edit 2: that's absolute max power. You'd have to actually measure the amp to have the power at 1%thd, which is a common figure to quote the power at. Sims say 20mW (0.8Vrms into 32r) but it's at best a ballpark figure, at worst completely off.