ben. Posted May 3, 2005 Share Posted May 3, 2005 I'm at home on my laggard dial up, and it's tough to search for detailed info on this. Can anyone "nutshell" the interaction between a field coil speaker and the power amp driving it? Specifically, what impedance does a typical field coil present to the amplifier? My initial hunch is that it's quite high. If that is the case, what is required to make an amplifier designed for a field coil speaker work properly with a permanent magnet speaker? Would it be necessary to change OPTs? Quote Link to comment Share on other sites More sharing options...
TBrennan Posted May 4, 2005 Share Posted May 4, 2005 Ben--Ask at the Audio Asylum high efficiency forum. Several very astute field-coil guys hangout there. Quote Link to comment Share on other sites More sharing options...
ben. Posted May 4, 2005 Author Share Posted May 4, 2005 Thanks, Tom. Will do. I did a search over there, but it was a bit much to wade through all the unrelated posts. Quote Link to comment Share on other sites More sharing options...
boom3 Posted May 4, 2005 Share Posted May 4, 2005 I can't give you the whole magella, but I can share this: In the past, some tube amps, primarily in large console radio/radio-phonos, used the field coil of the electrodynamic speaker as a choke for the power supply. That is still possible, but it requires a custom design of the amp to permit the fieldcoil to do 'double duty'. AA is a very busy forum, and even within the subsets like Hi Eff, it takes a while to find useful info. I'd suggest going to a cybercafe or library with a fast connection and doing your searches there. Quote Link to comment Share on other sites More sharing options...
k2dx Posted May 4, 2005 Share Posted May 4, 2005 AS I recall it, the field coil served two purposes, as a smoothing choke in a B+ power supply and eliminated the need for a permanent magnet in the speaker. To use an amp designed for a field coil speaker you would need to use a smoothing choke in the B+ supply and a permanent magnet speaker with a voice coil matching the output transformer. The B+ supply *may* work out with a resistor in place of the choke.... 1 Quote Link to comment Share on other sites More sharing options...
Duke Spinner Posted May 5, 2005 Share Posted May 5, 2005 no can do, Ben .. a field coil amp will not work with a PM Speaker you are sending a high voltage outta them terminals .. ! Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.