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Old 11th July 2011, 10:57 PM   #1
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Default F4 vs Circlotron

Anybody built both and can compare the sound. The circlotron seems to give better measurements. Nelson, do you have an opinion.
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Old 12th July 2011, 01:11 AM   #2
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I'm not N.P. And, I havent built one in 5 years or so (A Circlotron). You say "seems to give better measurements" what measurements are those?
I think my next Circlotron will be a Lightspeed like circuit feeding a Comp JFET buffer feeding an LL7905 spliting to two R100 pair in Circlotron Config...
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Old 12th July 2011, 01:26 AM   #3
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As you know, I have some new SS fets to play with and while waiting on components, I am thinking of possible implementations. I already have two sets of F4 boards that I purchased to eventually use in biamped OB. Along with topologies we have discussed in other threads, I have considered using the R085 in a preamp like GroundedGrid or other FE that could swing the voltage necessary to drive the F4. In general reading on Nelson's site, I came across the circltron article and noticed the measurements looked better than the F4, therefore I asked. It is difficult waiting for parts and even more difficult doing all this with 4 kids. Sometimes I only have time to ask questions. My building time must be as educated and as efficient as possible.
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Old 12th July 2011, 01:52 AM   #4
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Well, I guess your talking about Mike R's. Amazing FET Circlotron? I like that design but, I'm of the opinion the original circlotrons were followers. Mike's is not. EUVL's is also not. A common source version is interesting but it's not circlotron to me! I think Mike's version is a cross between circlotron and F5. A very good one
I think the circlotron topology would be like the F4 more if using Toshiba parts in the F4. IRFs are likely to introduce a little more second harmonic that the F4 topology typically does not have.
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Old 12th July 2011, 02:05 AM   #5
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All the more reason to consider it, wouldn't you agree. If nothing else, it has possibilties. I like Nelson's move towards a modular approach. Perhaps that is why power buffers are grabbing my interest.
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Old 12th July 2011, 02:57 AM   #6
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Are you guys talking PPP , i thought only tubes could be a circlotron ..?
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Old 12th July 2011, 11:34 AM   #7
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I'm not sure which one of those P things you call it? Push-Pull sounds close enough to me? I guess balanced and differential fit also?
Why do you think only tubes could do the Circlotron thing. It's just another symetrical aproach to cancel non linearity with the other "Side" of the circuit. getting the operating point in a good place for the gain elements is the important part.
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Old 12th July 2011, 12:01 PM   #8
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PPP is parallel push pull i believe. I have depletion mode Jfets, which are almost exactly like tubes with the exception of their response curves.
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