I've done my share of building since 1965; when I assembled a 1N34 Germanium diode AM receiver. I enjoy thinking about, and analyzing the good work y'all are doing. It is therapeutic diyAudio building by proxy.
First of all, Idss as can be seen in the SemiSouth Data Sheet is described as leakage current D-S with the gate pulled down (OFF) and 1200V D-S. Are we operating anywhere near these conditions? 
Lets try to be a little more on top of what we're trying to say
Having said that, I'ld like to give this Zen Pot a try. O.K. That's not what I wanted to say either... A sine wave coming out of one of these devices will not have a positive going 1/2 sine that is equal in amplitude to th Neg going 1/2 sine. That's just the way it ussually is. I think this will cause even order harmonics to be generated, 2nd, 4th, 6th etc. Not odd 3rd, 5th, etc. Also, when looking at the signal on a scope, you will notice a median or average towards the positive. This is not DC Offset! Spice will tell you if there is offset in the signal even with the DC output at 0V. It just means that when the output offset is 0V and the speaker is at rest, the signal will force more cone movement to the positive side than the negative side. Pumping up the bias will ussually reduce this condition I beleive. Balancing another device against it, operating in 180 degrees different phase, as in this amplifier, should exhibit the opposit effect and cancel the imballance allowing the speaker to move an equal amount in both going out and going in. This would ideally remove the even harmonics. It dosen't necessarily make the odd harmonics increased in amplitude, justs cancels the evens and leaves whatever odds harmonics still there.
Adjusting the pot, the Zen Pot (just has a nice ring to it) is a method of manipulating the gain and or signal, in the top device or the bottom(as in the BA3 FE) device to achieve this balance, or not. It dosent add distortion per se, it only manipulates some factors to control it.
Lets try to be a little more on top of what we're trying to say
Having said that, I'ld like to give this Zen Pot a try.
O.K. That's not what I wanted to say either... A sine wave coming out of one of these devices will not have a positive going 1/2 sine that is equal in amplitude to th Neg going 1/2 sine. That's just the way it ussually is. I think this will cause even order harmonics to be generated, 2nd, 4th, 6th etc. Not odd 3rd, 5th, etc. Also, when looking at the signal on a scope, you will notice a median or average towards the positive. This is not DC Offset! Spice will tell you if there is offset in the signal even with the DC output at 0V. It just means that when the output offset is 0V and the speaker is at rest, the signal will force more cone movement to the positive side than the negative side. Pumping up the bias will ussually reduce this condition I beleive. Balancing another device against it, operating in 180 degrees different phase, as in this amplifier, should exhibit the opposit effect and cancel the imballance allowing the speaker to move an equal amount in both going out and going in. This would ideally remove the even harmonics. It dosen't necessarily make the odd harmonics increased in amplitude, justs cancels the evens and leaves whatever odds harmonics still there.Adjusting the pot, the Zen Pot (just has a nice ring to it) is a method of manipulating the gain and or signal, in the top device or the bottom(as in the BA3 FE) device to achieve this balance, or not. It dosent add distortion per se, it only manipulates some factors to control it.
flg: Thanks for your explanation. lhquam: Zen Pot originated as a resistor in US Patent # 5,710,522; inventor Nelson Pass.Adjusting the pot, the Zen Pot (just has a nice ring to it) is a method of manipulating the gain and or signal, in the top device or the bottom(as in the BA3 FE) device to achieve this balance, or not. It dosent add distortion per se, it only manipulates some factors to control it.
It is best to visit www.uspto.gov . Search for this patent by its number. Click on Images to see the first page which shows the schematic of this invention.
Or read the Zen ver2 paper authored by the One and Only, in wich you will find this quote "In 1991 I authored U.S. patent # 5,710,522 which detailed the operation of an active current source which was constant for DC characteristics but variable at AC frequencies and which could track an arbitrary percentage of output current to a load, relieving the active single- ended Class A gain device of some of the work."
I beleive starting here would be good. But then
ZM, why do you think that is? I don't know if I've ever heard a good reason?
Additionally, I actually caught N.P. mentioning something I didn't understand in the F5 thread I think. I replied and he might have told us there. We didn't have Zen Pot at the time, but I still don't remember. Later in the BA-3 article I would say, he officially introduced it to us IIRC
OK, This is where I saw it, before it was called Zen Pot
http://www.diyaudio.com/forums/pass-labs/121228-f5-power-amplifier-1086.html#post2667532
wrong
Mighty ZM invented both Aleph CCS and ZAP ;
in fact , when I think a little , Mighty ZM also invented rotating magnetic field
illustration :
if you make R5 as variable resistor OR if you put 100R pot across R4 and connect C1's feed to wiper , you're having ZAP on Aleph
Mighty ZM invented both Aleph CCS and ZAP ;
in fact , when I think a little , Mighty ZM also invented rotating magnetic field
illustration :
if you make R5 as variable resistor OR if you put 100R pot across R4 and connect C1's feed to wiper , you're having ZAP on Aleph
Attachments
flg and ZM. Which Pass Amp
I'm not sure I would agree the control of Aleph current source modulation % is the same thing as the "P3" or Zen Pot. As I said, Papa put it on the F5 and the BA-3 F.E. The SRPP type circuits with tappable output point is a similar function though, as is the Aleph.
I would also not agree it is an introduction of "good distortion". It is more of the same distortion being introduced out of phase causing cancelation of the distortion.
I would also not agree it is an introduction of "good distortion". It is more of the same distortion being introduced out of phase causing cancelation of the distortion.
As far as I know the Zen Pot is used only in NFB devices like SIT2 (no feedback) and I also could imagine that the feedback loop counteracts....
OK , to put question backwards : what you think that Pa find worthy enough , to place pot for fiddlin' with ?
........know don't really I
everything is explained in posts regarding magic pot in last iteration of F5 ;
anyway , I'm literate enough to grasp what is it for , but certainly not smart enough to give you numeric tables
everything is in Sweet Spot article , but not entirely laid on table ; I resume - from several reasons , both objective and subjective
anyway , I'm literate enough to grasp what is it for , but certainly not smart enough to give you numeric tables
everything is in Sweet Spot article , but not entirely laid on table ; I resume - from several reasons , both objective and subjective
