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Old 1st October 2012, 11:17 AM   #2161
flg is offline flg  United States
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The Zen Pot idea would be considered local feedback I would think. But, what do I know
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Old 1st October 2012, 11:45 AM   #2162
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I'll leave the technical mumbo jumbo o the smart people, but when building the BA3, I asked Nelson whether or not going balanced would negate the trimming i had done with P3(yielding higher 2K harmonics) would be nulled by balanced implementation. If i remember correctly, he stated that although it would occur, the character of the independent halves would still remain to a certain degree. I say this to answer the questions about whether or not the changes would be nulled by OLF. Nelson told us the importance of the sweet spot, showed us how to do it with P3. We got some help from ZM with Zen Pot on setups like this and J2. Anything else is going to take building and testing, not speculating. Go blow some @$!% up and lets have some fun.
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Old 1st October 2012, 12:02 PM   #2163
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Quote:
Originally Posted by flg View Post
The Zen Pot idea would be considered local feedback I would think. But, what do I know
in some cases yes , in some cases not

Quote:
Originally Posted by Zen Mod View Post
speaking strictly about F6 and MR's amp - with pot you're varying degree of either direct AC modulation , or AC degeneration (indirectly influencing AC modulation)
......

example :
Attached Files
File Type: pdf Pages from SP 08.pdf (65.7 KB, 60 views)
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Old 1st October 2012, 12:07 PM   #2164
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ya'll remember advices for venerable JLH amp , and choosing output with higher beta to upper(?) position ?
It was lower position.
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Old 1st October 2012, 12:30 PM   #2165
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tnx

question mark solved
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Old 1st October 2012, 01:39 PM   #2166
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Default Zen Pot

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Originally Posted by buzzforb View Post
I'll leave the technical mumbo jumbo o the smart people, but when building the BA3, I asked Nelson whether or not going balanced would negate the trimming i had done with P3(yielding higher 2K harmonics) would be nulled by balanced implementation. If i remember correctly, he stated that although it would occur, the character of the independent halves would still remain to a certain degree. I say this to answer the questions about whether or not the changes would be nulled by OLF. Nelson told us the importance of the sweet spot, showed us how to do it with P3. We got some help from ZM with Zen Pot on setups like this and J2. Anything else is going to take building and testing, not speculating. Go blow some @$!% up and lets have some fun.




Fine people: We have not been on the same page regarding " Zen Pot". I hope my post will clear this inadvertent confusion. Please consult the attached file ZenPot.pdf.
  • Figure 1 shows a constant current source loading a "FET" gain stage. This [Prior Art] was the practice of Mr. Pass in some of his amps
  • Figure 1a shows a Modulated Current Source loading the same "FET" gain stage. The addition of R and C to the basic circuit of Figure 1 enabled this modulation [Invention] . Nelson S. Pass was granted US Patent # 5,710,522. The resistor R is not Zen Pot.
  • Figure 2 shows a simplified diagram of the front end [FE] of F5. I hand copied it from the 2012 F5 Turbo article on www.firstwatt.com. Zen Pot is component P3 [200 Ohms plus other resistors]. The specific importance of P3 follows [cut and pasted from the article]
"One thing that many will appreciate is the addition of P3, which due to inattention on my part was not public until recently. It allows the adjustment of the distortion character between complete nulling of the second harmonic distortion to an arbitrary ratio of second to third harmonic. It definitely alters the sound, and reaffirms that things going on below 0.1% are audible. In anycase, you can adjust it to taste. Here is what the waveform looks like when the second harmonic is allowed to be about....




The following puts us all on the same sonic wavelength.
  • The proposed physical location [and sonic value] of P3 in F6 and its clones belongs in its FE circuit and not in the output stage.
  • Does anyone wish/need to practice the teaching of US 5,710,522 in the output stage of F6 and its clones? The output configuration of F6 looks promising like in those of Figures 1, 1a.
  • No relation between the resistor R in US 5,710,522 [Figure 1a] and Zen Pot [Figure 2]
I hope to have redeemed myself [mea culpa !] with this note.
Attached Files
File Type: pdf ZenPot.pdf (28.5 KB, 64 views)

Last edited by Antoinel; 1st October 2012 at 01:45 PM.
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Old 1st October 2012, 01:41 PM   #2167
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Same goal, different tool. Trust me
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Old 1st October 2012, 01:51 PM   #2168
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Originally Posted by buzzforb View Post
Same goal, different tool. Trust me
I hope that we cleared the frustrating confusion. The body of US 5,710,522 may show the significance of resistor R [Fig 1a] regarding the management of distortion. This is an example of me practicing diyaudio therapy by proxy.

Last edited by Antoinel; 1st October 2012 at 01:58 PM.
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Old 1st October 2012, 01:59 PM   #2169
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You misunderstood. Zen pot in F6 accomplishes same goal as P3 in F5. Same gola, different tool.
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Old 1st October 2012, 02:22 PM   #2170
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Originally Posted by buzzforb View Post
You misunderstood. Zen pot in F6 accomplishes same goal as P3 in F5. Same gola, different tool.
Thanks buzzforb. I fully agree with you regarding the proposed location and significance of Zen Pot in F6 and its clones.
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