Resistance of Plate Choke
- Thread starter JBasham
- Start date
Paul Joppa
Moderator
330 ohms - 165 per chamber. I rate it 80mADC and 23 henries; it runs at 70mA in Paramount with a bit more inductance at the lower current.
Thank you very much!
In the zone for replacement with the unused pair of EXO-04s I have. 10ma over the MQ rating, but I have been doing that to a pair of EXO-03 for years now with no ill effects.
But maybe overkill at 50 henries, especially since I run OB speakers that are 100db sensitive but don't do much under 100Hz. They're supported by stereo subwoofers with their own mono amps.
Does Mr. LeFevre's BH-7 upgrade raise the inductance over the stock choke (I'm not asking you to divulge specs), or make the magic happen some other way? If you're at liberty to share. If not, please accept my apologies for asking rude questions.
In the zone for replacement with the unused pair of EXO-04s I have. 10ma over the MQ rating, but I have been doing that to a pair of EXO-03 for years now with no ill effects.
But maybe overkill at 50 henries, especially since I run OB speakers that are 100db sensitive but don't do much under 100Hz. They're supported by stereo subwoofers with their own mono amps.
Does Mr. LeFevre's BH-7 upgrade raise the inductance over the stock choke (I'm not asking you to divulge specs), or make the magic happen some other way? If you're at liberty to share. If not, please accept my apologies for asking rude questions.
Along with increased inductance, if the capacitance of the plate choke can be decreased (which is likely over the PC-2), then high frequency response can be improved.
The EXO-04's are a pretty serious bit of kit, I'd try them in the circuit before drilling all the holes in the top plate (will they even fit?).
The EXO-04's are a pretty serious bit of kit, I'd try them in the circuit before drilling all the holes in the top plate (will they even fit?).
Paul Joppa
Moderator
Huh. I guess I'm out of the loop - I have not even heard of an EXO-004.
The BH-7 runs (in my tests) 25 henries at the maximum current of 76mA; at 70mA in Paramount 300B it's 27 henries. So it's a slight improvement in that respect. It has other internal design features and measurements that I like but they are more MQ-proprietary.
For what it's worth, more inductance is always better in a plate choke. It just costs more. :^)
The BH-7 runs (in my tests) 25 henries at the maximum current of 76mA; at 70mA in Paramount 300B it's 27 henries. So it's a slight improvement in that respect. It has other internal design features and measurements that I like but they are more MQ-proprietary.
For what it's worth, more inductance is always better in a plate choke. It just costs more. :^)
Paul Joppa
Moderator
The Brainiac was designed for 300Bs at 70mA, and had 30 henries inductance at 70mA maximum; it's built on the same core as the TFA-2004 so they look really good together. I had a full set once, with brass covers, but the amp they were in went on loan many years ago and hasn't been seen since.
I did (finally!) find some specs on an EXO-004: 50 henries at 60mA; DCR 317 ohms. My files are a mess; I don't think I've ever seen one.
I did (finally!) find some specs on an EXO-004: 50 henries at 60mA; DCR 317 ohms. My files are a mess; I don't think I've ever seen one.
Sorry to confuse things (though it happens to me often).
Like the EXO-03, which I sometimes see as the EXO-003, I have seen it as the EXO-004 or the EXO-04. They were pretty close in spec, but the 04/004 has bell ends for top mounting.
But wait, Mike explained it better:
http://db.audioasylum.com/mhtml/m.html?forum=magnequest&n=403&highlight=EXO-004&r=&search_url=%2Fcgi%2Fsearch.mpl%3F
I got a pair from his last run in 2006.
Like the EXO-03, which I sometimes see as the EXO-003, I have seen it as the EXO-004 or the EXO-04. They were pretty close in spec, but the 04/004 has bell ends for top mounting.
But wait, Mike explained it better:
http://db.audioasylum.com/mhtml/m.html?forum=magnequest&n=403&highlight=EXO-004&r=&search_url=%2Fcgi%2Fsearch.mpl%3F
I got a pair from his last run in 2006.
Paul Joppa
Moderator
I note that Mike's web page currently says 40 henries for the EXO-003. That's consistent with my own measurements. It's easy to get 20-30% differences in measurements depending on the method used; mine is fairly conservative.
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