First, let me say that I have successfully built an RH84 using motor run caps and Transcendar OPT’s, and it is a most wonderful amp. Now I’ve picked up a small Zenith SE el84 console and I’m interested in changing the circuit into another RH84, but the Zenith is set up with three OPT’s, two small ones for left/right and a third, larger one for a central ten inch bass speaker. I’ve traced the RH84 schematic with two signal portions for left/right, and tried to graft in the third OPT in the way it was connected originally, but I don’t know for sure if it will work. (Again, my apologies Mr. Kitic, I understand you don’t care for modifications to your design, and yet, curiosity compels me…)
Would anyone with actual knowledge care to comment on my effort? I don’t have the Zenith schematic, and I haven’t measured the impedance of the OPT’s, so I’m kinda just thinking out loud right now. I can always buy a couple of small Edcors and change to two speakers, but it’s all set up for the three, and the connections for the third look to be straightforward… I know that doesn’t mean it will work though. All comments are welcome, even if it’s just that I’m wasting my time. Thanks!
Would anyone with actual knowledge care to comment on my effort? I don’t have the Zenith schematic, and I haven’t measured the impedance of the OPT’s, so I’m kinda just thinking out loud right now. I can always buy a couple of small Edcors and change to two speakers, but it’s all set up for the three, and the connections for the third look to be straightforward… I know that doesn’t mean it will work though. All comments are welcome, even if it’s just that I’m wasting my time. Thanks!
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I've traced a couple of these... i don't know if you want the separate B+ feed to the SE OPTs. And the bracketed caps will block low frequency signal to the bass driver.
We need some guys that really know in the thread.
This was a fairly common way of adding a common woofer. The PP OPT acts as both an OPT and as a filter choke
The more upmarket ones had a 3rd amplifier for the bass.
dave
We need some guys that really know in the thread.
This was a fairly common way of adding a common woofer. The PP OPT acts as both an OPT and as a filter choke
The more upmarket ones had a 3rd amplifier for the bass.
dave
I've occasionally pondered it, and it surprises me that diy'ers aren't currently taking this approach: two widebands a single woofer. It seems to have a great deal going for it. I've got an old phonola sort of thing with a terrible (and unsafe power supply less) amp that uses two little alnico satellite drivers and a bigger woofer in the big box. I know plenty of consoles have done it. It seems like a great way to do either a small main system, or especially a desktop system. Maybe something with the tiny Fostex's and a highish efficiency woofer? The world is full of ideal donor units for drivers and iron as well, but I can't remember seeing anyone build such a system. I hope folks chime in.
pj
www.wildburroaudio.com
pj
www.wildburroaudio.com
I sure hope it works, the console is small, but is in pretty nice shape, and it fits perfectly in my shop room. - Status
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