EL86 OTL

[krzanik]

Any thoughts on this? [URL=http://www.bonavolta.ch/hobby/en/audio/el86.htm]

It's very appealing (no output transform$rs, ch$ap tubes). I haven't seen anyone building this so I suspect there is a catch?

[Miles Prower]

It's an SRPP. This will be balanced for the one specific load impedance where the source current and the sink current are equal. Otherwise, it goes out of balance and the distortion rises (speeks are anything but a constant impedance). The stated Zo is 800R -- 1000R, and that means a pretty poor damping factor that'll compromise low end sonics. An 8uF coupling capacitor seems to be way too small.

Might be OK for a quick 'n' dirty amp (eg. output stage for a SW xcvr) but definitely not HiFi.

[poynton]

Originally posted by Miles Prower
It's an SRPP. ............. but definitely not HiFi.

www.bonavolta.ch/hobby/en/audio/el86.htm


This circuit was specifically designed (as HIfi) for the full-range , high-inpedance speakers designed by Philips.

These speakers are still available on Fleabay



Andy

[dhaen]

I suppose it depends on one's definition of HiFi...
Here's more detailed info (courtesy Franks electron tube pages):

EL86

[krzanik]

Thanks for the information. Looks like buying the speakers would defeat the purpose of saving money on output transformers. I figured there had to be a catch, otherwise people would be building these things left and right.