diyAudio Forums Archive > Top > Amplifiers > Pass Labs Pages: [1] 2 3  Let me lite fire - Nelson Pass F1 - Click HERE for Original Thread jh6you Crying like a baby, one small girl was afraid of walking into the operation room . . . I said it's a small thing . . . I pushed her back into the room . . . It was not a cancer, but something under the skin . . . Mmm . . . she was born with it . . . Waiting outside . . . I was thinking about . . . Pass Zens and the First Watt . . . Yeah, it's time . . . Here is my concept darwing. I will not draw any details . . . I am afraid of Nelson Pass . . . My target is 5W@8ohms and 10W@4ohms. A-class of efficiency about 5%. Of course, the current source amplifier. Nelson Pass, is the concept feasible? Will it drive normal 2-way 90dB speakers too? Or, should I change the x-over network? Or, should I go with the efficient single unit speakers? Regards jH gl Hi JH, Mr. Pass has already given away most if not all of the F1 design in the form of small hints on this board and in the ZEN articles on PASSDIY. I would start off by doing a search on the subject. I have built a transconductance SOZ from this information. I am still debugging a few things but it does work and it does make music. Some other people have already had good luck converting some of the other Zen's to work as current amps, if you need something right away. Your other questions on 2 way speakers and crossovers are already answered in the current source amplifier and crossover papers on the PASSDIY website. Cheers, GL thorstenlarsen Hi jH ! The schematic you have shown looks like an X-SOZ, without any series resistor at the input. It will have a very low input resistance, because of the feedback from drain to source. If you add a series resistor at the input, the amp will turn into a voltage amplifier. Thorsten acaudio I thought a little about this: Adam Nelson Pass Well guys, if you're going to second-guess the F1, you'd better hurry up, as the service manual will go up next month or so. :cool: JEKYLL Yyyyyyyeeeeeesssssss!!!!!!!!!!!!!!!!!!!! gl Mr. Pass, I noticed that Mark Sammut has added a note to his site that says that he will run out of F1's by the end of this month. I took that to mean the current batch he had on hand, but I guess it means for all time. GL Nelson Pass The F2 is out, and there will be poop up on the web site www.firstwatt.com in a couple of days. Probably I will close out new F1 availability sometime next month, although RenoMark is anticipating some trade-ins on F2's and subsequent product. :cool: jh6you Oh . . . the limited number of the first edition is almost slod out . . . ? In one month . . . gl, I will read his writings. Thorsten, thanks for the hint about the input R. acaudio, mine is almost the same as yours. Did you build it? Actually, mine was inspired by Zen V6 and Zen V7 . . . I will go out to find IRF240 and collect them and others . . . Regards jH jh6you You are right. The simplified Fi schematic is already at www.firstwatt.com . . . So, mine is found as feasible . . . Yeah . . . Nelson Pass gives no sanwer . . . Often it means yes . . . I know . . . ;) Regards jH Nelson Pass Don't get too excited - the F1 is basically a tarted up SOZ. It's the little details that probably will be of interest. :cool: jh6you Whatever you say . . . still excited . . . Learning good thing from you . . . to be excited . . . My teeth are getting terrible . . . This morning, I was brushing, thinking about the amp gain . . . Here is revision 1. Regards jH thorstenlarsen Hi jH ! "It will have a very low input resistance, because of the feedback from drain to source. " Sorry I meant : from drain to gate Thorsten jh6you Now ok re. the input impedance . . . ? Regards jH Nelson Pass quote: Originally posted by thorstenlarsen "It will have a very low input resistance, because of the feedback from drain to source. " That would be function of the actual resistor values. steenoe quote: I will go out to find IRF240 and collect them and others . . . If you really have to be so poetic about it, I can get them for you;) No trouble at all. If Nelson is a "Picasso", you have got to be a "London":) Or Browning, maybe?? Steen:cool: eLarson A very low input impedance would be just the thing for being driven by a current source. Nelson Pass Actually the F1 use a very high impedance - the loop is just just to set DC. steenoe quote: A very low input impedance would be just the thing for being driven by a current source. If I understand Larsons post correctly, the low impedance would be the speakers! The current-source would be the amp! Correct me if wrong? Steen:) gl Mr. Pass, The specifications in the F1 owners manual states that the input impedance in balanced mode is 100K and unbalanced is 50K. However, the FirstWatt product page for the F1 gives the input impedance (no qualification) as 80K. Which number is correct? The output swing is also given as +-20V but the amp has a single voltage PS and the outputs are biased to sit at +13.8V. Should the spec read 20V P-P perhaps? Cheers, GL jh6you I estimate that 40Vp-p comes . . . We however might have no chance to climb up that much because the distorsion in signal would climb up faster. . . :) Regards jH GRollins I think it's safe to say that a 10W (presumed RMS) amp would deliver something on the order of 20Vp-p. Look at it this way. The fundamental topology is a differential. To a first approximation, each side of the differential can travel from the absolute DC offset of 13.8VDC up to the rail, and probably a similar distance down. Nelson said the rail is, what, 25V or so? It's in one of the threads, somewhere. For the moment assume 25V. Okay so that means (quick fiddle on a calculator) a little over 11V up and about that same voltage down. Given that it's a differential, both of these are occuring at the same time, just as though two kids were going up and down on a see-saw. Subtract a little for housekeeping for the CCS up top and you'll end up with a number fairly close to the 20Vp-p figure. That's not to say that you can't scale the general idea up or down, just the way that the SOZ can be ramped up to any arbitrary amount of wattage with big enough heatsinks and output devices. Well, and a beefy power supply, of course. Anyone want to make a 50W version? Grey jh6you Damn . . . English is difficult . . . Every time I can’t remember spelling of chassis . . . And why it reads /’shaesi/ . . . Terrable ! ! ! Here is the box dimension I will build soon. I think I can get the size of heat sinks easily here. steenoe I really need to find IRF140 or 240 around here. At least 10 for one F1. If possible, matched . . . I do not have the qualification certificate for my soldering skill. So I always need 50% spare in case. It makes total 15. Wait a minute . . . I might build two F1s. So, total “30.” I need to hurry up . . . Before my wife and sons visit me . . . My wife tries to stop my diy and smoking . . . for safety and health (Maybe for saving money) . . . She never gives up . . . I do not give up yet either . . . Regards jH lumanauw I just read the manual of F2. Could someone help me here? The key words are "voltage in, current out, no feedback". What it would be like if you make a preamp like F2? No feedback preamp, which its voltage gain depends on 1 final resistor value? jh6you Grey Is it very late night there . . . ? ;) Or, I am smoking too much . . . :djinn: As you says, while "A" side go up to 10, "B" goes down to -10. So total difference is +20 from "A"'s point of view. And opposite direction -20. Mmm . . . +/-20 (=40p-p?) "Why are you making amps again and again . . . You have already enough . . ." Hmm . . . I have never complained her buying shoes so often and many . . . Listen to me! Even Nelson Pass uses the one and the only shoes, everywhere, inside limo, at concert, and at exhibition . . . Regards jH GRollins The voltages don't add that way. It's just the one top-to-bottom value. Imagine that you are the load. What is the maximum voltage swing that you could ever see? It's either +10 and -10 or -10 and +10. You can't see both at the same time. Grey jh6you We are thinking about the same. You: It's either +10 and -10 or -10 and +10. You: It's either +20 and 0 or 0 and -20. :cool: Grey . . . Do you know where he is . . . ? His tonge is tough . . . Particularly to you . . . So I used to call him Jaws . . . I remember he is from Texas . . . Why he is shut up his mouth . . . ? I read here and sometimes feel boring . . . Where are you Jaws . . . ? Regards jH jacco vermeulen quote: Originally posted by Nelson Pass the F1 is basically a tarted up SOZ. Isn't that Elliot's punch line ? The F2 manual is very enjoyable to read. I gave my dogs their notice for 10 months from now. Is the low gain of the F2 not an important factor ? jh6you Suddenly about F2 . . . here . . . ? Attached is drawn just to try to kill time . . . Regards jH jacco vermeulen quote: Originally posted by jh6you [i]Suddenly about F2 . . . here . . . ? Blame Lumanauw ! The F2 manual is a nice addition to the one of the F1, imo. For one, as it clearly shows how 2d harmonics cancel eachother out on the F1, brilliant. jh6you Lumanauw, bad man! :D . . Regards jH promitheus I used to be schizophrenic but not we are doing better. :D I dont want to play it smart here :clown: Well actually you dont add the voltages you substract them. Voltage is a potential difference. V1 - V2 10V - (-10V) = 10V + 10V = 20V Vix Hi! Nelson, thanks a lot for "uncovering" a F1 schematic. But since I am a guy who prefers a 2-nd harmonic, it seems that I'll have to wait for you to make and sell 100 pieces of F2, in order to get a schematics (maybe in July 2006?):D In fact, I think pass DIY community may well know that it has been already uncovered here on forum.:clown: Hence, I don't expect that F2 be something very different than what was posted on a thread "Zen without feedback". On the other hand, I still believe that there is another rabbit in a hat:devilr: For me, the choice is clear: I will build a "no feedback ZEN" as presented on the forum, let it work as it may be, and modify it whenever you publish "the proper version". Anyway, thanks a lot for your input, comments and hints. Best Regards, Viktor jh6you Phew . . . Make F1 first . . . Enjoy 3rd harmonic sound first . . . Tired . . . ? Go to the kitchen . . . Bring the scissors . . . Draw the center line of the F1 . . . And cut it along the CL into two halves . . . fold them . . . Make them in parallel . . . Add output caps . . . Now you have F2 . . . Enjoy 2nd harmonic sound . . . :eek: Regards jH Nelson Pass The F2 manual does make erroneous reference to "XLR connector" and refers to the input impedance as being "balanced" which it is not. /pass/: makes new manuals by poorly editing old ones. :cool: GRollins Need an editor? Grey Nelson Pass Thanks, but if my documentation got too professional, the I would lose standing in the audio community. :cool: jacco vermeulen Another way of saying it would become boring! :clown: jh6you I want to read F2 manual . . . But, I can’t connect your web site . . . Too many visitors are in the long queue. . . ? ? ? Otherwise, me, on the black list . . . ? ? ? Nelson Pass If I use 0R22 source resistors, is the inner voltage gain of F1 could be approximated as about 25dB with 8ohm spker? I want to roughly figure out the input impedances for mine. Thanks. Regards jH jh6you I design the front side of the chassis . . . The name, Pass, consists of front air holes . . . He would accept using of his name . . . I think . . . Regards jH MikeW I will volunteer my services to listen and test to the F2 in a home environment. You have my address. Don't forget the full range speakers. :clown: apassgear Kind of big front JH, :bigeyes: 480mm!!! jh6you Yes. It's wide. At first, I was thinking about 430mm, which is the same as the body width, but changed mind to 480mm to have 25mm wings to the left and right. The final dimensions might be slightly modified. It would depend on the heat sink dimensions that I will order tomorrow. I am going to have upper CCSs using N- MOSFET . . . But, using P- could be better . . . ? More quieter . . . ? Hmmmmmm . . . . . . In a dilemma . . . Regards jH steenoe quote: Kind of big front JH, 480mm!!! Just what I thought! That geometry wouldn't please my eyes:xeye: Seems like the chassis would be 480x480! Not a nice sight to me, sorry JH:D Steen.:cool: Nelson Pass quote: Originally posted by jh6you [i]If I use 0R22 source resistors, is the inner voltage gain of F1 could be approximated as about 25dB with 8ohm spker? I want to roughly figure out the input impedances for mine. The gain of an F1 is about 13.9 dB. The F2 is about 15.6 dB. jh6you Ladies and gentlemen! . . . Steenoe is my wife . . . :yikes: Regards jH jh6you This time I'd like to have a good inner space . . . Regards jH jh6you Thanks, Nelson Pass. Regards jH jh6you Failed to get IRF240 . . . IRF150 and 250 only available here . . . Both IRF150 and 250 have high input bypass pF, compared with IRF240. IRF150 about 2.5 times while IRF250 about 2 times higher. So, If IRF240 gives me fc at 100kH, IRF250 would give me fc at 50kHz. Will it be a great concern if the amp should live with fc at 50kHz? Estimated based on C in(Miller) = Cgs + Cds x (1+A) Regards jH Nelson Pass If you drive it with a low source impedance, it should not be an issue. steenoe quote: Ladies and gentlemen! . . . Steenoe is my wife . . . Thanks a lot, JH. I will take that as a compliment:D Still, an even sided square s*cks, somehow:angel: Steen:cool: BTW. quote: Failed to get IRF240 . Sorry to say so, but so did I! I did try to connect to a cheap source for those, on your account, But they havent got any, anyway's!!:bawling: jh6you Tanks to Nelson, i with confidence bought IRFP250 . . . The heat sink shop did not wait for me with the size i wished . . . I re-ordered the size of 480x130x6 having 11 fins . . . The size was by eye measure . . . not by calculation . . . Feel somewhat smaller . . . Anyhow . . . The attached drawing is the final dimension of the chassis . . . Hope this time steenoe will say ok . . . Then, I will sign the divoce paper . . . Nelson From now on I'd like to call you Nelson . . . Do you mind . . . ? My F1 circuit is based on your Zen V7. For the two current sources, I have thought to use p-channel mosfet. But, simply to use one IRF250 for all, I go with n-channel. The current sink is exactly same as the one of Zen V7. By the way, as shown in my concept drawing Rev.2 above, I have Rgs (instead of the R going to the ground in Zen V7). I have this Rgs for two things. One is for DC control, and another is to let it stay there as a form of boostrapping. Could you let me know whether "the form of bootstrapping" will do its function? If so, I might understand the circuit much better. I have lack self-confidence as I am not an electrician . . . Regards jH Nelson Pass quote: Originally posted by jh6you From now on I'd like to call you Nelson . . . Do you mind . . . ? By the way, as shown in my concept drawing Rev.2 above, I have Rgs (instead of the R going to the ground in Zen V7). I have this Rgs for two things. One is for DC control, and another is to let it stay there as a form of boostrapping. Could you let me know whether "the form of bootstrapping" will do its function? If so, I might understand the circuit much better. I have lack self-confidence as I am not an electrician . . . 1) No, I don't mind. Everybody else does, if I'm lucky. 2) If it works, fine. I do it a little differently, looking for greater stability of voltage across the bottom current source, as you will see in the upcoming service manual. 3) Very few electricians as defined in the U.S. have much understanding of electronics - they specialize in routing power off the AC power lines. eLarson quote: Originally posted by Nelson Pass 2) If it works, fine. I do it a little differently, looking for greater stability of voltage across the bottom current source... Like the one's feeding the input stage of the A75, by any chance? thorstenlarsen Hi jH ! I suggest that you find another way of biassing your gates. The resistors from gates to sources will give voltage-feedback, which will lower both the input and output impedance. It will turn the amp into a voltage amplifier, which was not what you wanted ? Maybe you could just use a voltage divider from supply to ground and bypass the lower resistor with a cap. Then just put 47 KOhm from there to the gate. Then you wont need the series resistor. Or you can use a dual supply and just tie the gates to ground. I`m looking forward to hearing about your listening impressions. Thorsten steenoe quote: Hope this time steenoe will say ok . . . Indeed, he does:D That chassis looks very pleasing:) I just hope you can still fit the trafo's in there:xeye: Steen:) jh6you steenoe I signed the paper. ;) my trafo is 12-0 12-0 400VA. The dimension is 130mmx130mmx8omm. Two of them will walk side by side into the inner space . . . :) I misprinted. The size of heat sink is 480mmx130mmx60mm. Thorsten I 80% understand what you are talking about. Thanks! If it is turned out as a voltage amplifier, it would be still not bad. If so, I could test it on my current speaker . . . Actually, I like to do exploring . . . learning . . . Later, I could switch the circuit into the original Nelson's F1 . . . And, would test it on my new single drive spk . . . Nelson It is somewhat difficult for me to interprete "If it works,". Best Regards jH Nelson Pass quote: Originally posted by jh6you It is somewhat difficult for me to interprete "If it works,". Well, the bias point on the Drains is either stable, or it wanders around. If it's stable, then it works. jh6you Eah . . . I couldn't sleep well for days, being afraid of the potential instable offsets . . . even if I put the source resistors below the gain mosfets . . . dreaming of a possible stability. My head is chaos . . . with the electron traversing all of time and space . . . totally . . . out of control . . . Still I can't open the firstwatt web site . . . Regards jH GRollins Resistors below the Sources alone will not give you sufficient stability. Your worst case scenario is that one output's DC offset drifts upwards while the other drifts down. The resulting DC will flow through your voice coil, leading to unpleasant results. Ideas for you to play with: --The simplest solution is to cap couple the outputs. It's reliable, easy, and guaranteed to stop the DC. The downside is that the caps will have some effect on the sound quality. They'll have to be fairly high capacitance, which means electrolytics--although you could easily bypass them with film caps to help things out. Needless to say, this isn't what Nelson did on the F1, but it's quick and easy and you'll be able to sleep at night knowing that you won't roast your driver. --Take a look at the upper "load" current sources. (Assuming that the gain devices are well matched, any variation in the current feeding the differential itself will be common mode, and can basically be ignored...unless it gets so far off that you start getting asymmetrical clipping.) They're going to drift with temperature. First, you make them as thermally stable as possible, meaning lots of thermal mass. Then you create a feedback loop to monitor and correct the current regardless of temperature. --Create a feedback loop that corrects the DC offset as compared to ground. --Create a feedback loop that monitors the DC offset of the other side and sets out to match that (not some arbitrary DC voltage from ground). --Use resistors to bridge from each output to create a sort of virtual ground mid-way between the two output nodes. Use that as the basis for comparison. I'm just quoting from memory. I made a list of things and played with some of the most promising candidates. There are probably some that I'm forgetting. Just a few ideas for amusement. Grey jh6you Grey Well understood. Helpful and amusing. Please remember, two or at least one Rgs is adjustable. This is to let the DCs at the output nodes face the same value. And . . . I will rewrite . . . when the outside weather is cooled down . . . when my head is free from smell of alcohol . . . and when I finish cleaning up my desk for two week holidays . . . Regards jH jh6you I think that F1 is a single stage circuit. I believe that I could adjust the DC offset rather easily even if I use unmatched gain mosfets. I am considering one of two ways. (1) Having one adjustable resistor in the load current source system. (2) Or, having one adjustable Rgs. As Nelson has said many times, I should first adjust dc offset at cold operation condition, then, adjust once again at warm condition. I think that method (1) would assure me the stable dc offset. Am I too optimistic . . . ? Could you please give me wake-up call . . . ? Regards jH jh6you E.g. like this. Regards jH jh6you Heat sinks arrived . . . Trafo will come soon . . . O! I changed mind . . . It will be one 20-0 20-0 800VA, sized 152mm dia and 93mm high . . . The one remaining thing I am concerned about is whether the gate voltage of the current sink (lower ccs), about 4V, will be stay fixed or not. Here, as Nelson tipped, the stability of the drain Q voltages is a matter. Still I am not 100% sure of . . . Regards jH steenoe quote: Heat sinks arrived . . . Hmmmm... here goes your wife again:D I would mount the feets of your amp on the faceplate:) Otherwise, you could have trouble dissipating the heat;) Steen:cool: audiotux Heatsinks arrived .......... Hallo jh6you , very nice kitchen(Heat)-Sinks in Class A - Modus you can grilling very easy 2 T- Bone Steaks ! Greetings from Germany Jürgen apassgear quote: Originally posted by jh6you [i] Heat sinks arrived . . . I see you are not the only one using the kitchen table to brew the amps!!! Good work jh... Magura quote: Originally posted by apassgear I see you are not the only one using the kitchen table to brew the amps!!! Good work jh... A 100% clone, down to the smallest detail :D Magura :) jh6you Thanks for all of your encouragement. Steenoe I will see . . . and if necessary . . . will put the legs on the face plate . . . :) If so . . . the name Pass F1 will become a** holes . . . :eek: Here shows how I do hole-marking. Regards jH jh6you Trafo arrived . . . By the way, how to make the stable voltage across the bottom ccs . . . ? Tonight, I will try to figure it out . . . Regards jH jh6you Nelson I can't understand what are the causes of the unstable dc at drains. The Vbe varing with temperature in deck ccs could be one reason. The gate voltage of the bottom ccs must be stable so that it could not be a concern. But, the drain voltage of it could vary, as you say, so that it could be another reason, and probably this would be the most concern. If so, could I sense the varying darin voltage and cure it in simple way? Could you give me a tip? Don't say, "you will see it in a month or sooner . . . Muuuuuuhahahahahahaha . . ." Regards jH steenoe quote: Trafo arrived . . . That hardware is sweet looking! You've just got to love the sight of a rod of IRF's:D Almost, "Like a virgin". I am not sure Mr. Pass is up to revealing the details yet. As I understand from the postings on that matter, you have to wait till the end of this July:smash: Well, you signed the papers, but didn't get rid of me:rolleyes: Thats the way it works:D :D Steen:cool: GRollins Hint: Assuming that you're using a half-way decent CCS, it's not the one under the differential. The voltage is supposed to vary. It's constant current, not constant voltage. Grey Nelson Pass quote: Originally posted by steenoe I am not sure Mr. Pass is up to revealing the details yet. As I understand from the postings on that matter, you have to wait till the end of this July Why would I want to spoil your fun? :cool: jh6you Steen You did wrong. Really wrong. Nelson was about to inform some. But, you made him shut up. You know? I do not trust him much. His one month could be three months for us. No alimony for you!!! :headshot: Grey Your hint makes me further confused. Hmmm . . . Ok, I will post my circuit tomorrow . . . because I know mine is different from the Firstwatt F1. So, it should be no problem. Isn't it right, Nelson . . . ? I would like to hear all your opinions on it. Regards jH Nelson Pass quote: Originally posted by jh6you You did wrong. Really wrong. Nelson was about to inform some. But, you made him shut up. You know? I do not trust him much to quote the Joker: Who do you trust? Who do you trust? Me? I'm giving away money! And where's the Batman? He's home washing his tights! :clown: jh6you You are giving away! . . . nevertheless, not enough yet!! I am tired of this hot weather . . . And now tired of holiday beer . . . Here is my preliminary circuit. P1 is to adjust the offset close to 0 at output. Nelson says in the Zen V7 article: ". . . by a single ended input . . . one input is driven and the other is grounded and we see some voltage swing occur . . . and thus also on Drain of Q3 . . . variations as much as +/-3 Volts . . ." I think that he developed F1 mainly for tube preamp users, i.e. for the single ended pre. Then, to him, the voltage of variations of +/-3V must have been :eek: For the same reason, I would like to have R23 and R24. This is to make an ac ground at the drain of Q5. If it works as I think, the dc voltage across the bottom ccs could be getting stable. I wish to hear from you about all kind of comments. Any give-away-! comment would be appreciated. Phew . . . I am sweating too much . . . I need more beer . . . I will try this circuit until I get the efficient single unit drive . . . Regards jH stefanobilliani JH , do not forget to use smaller input capacitor remember .... you do not want the amp to work too much hard :redhot: And why that R1 R2 so big .... WALTER BURKHARD Hi jh6you can you contact me to my privat email walter_burkhardt@web.de regards walter Blues My take on the F1...can't get it to 10W@8ohms though. Is that 10Wrms or 10Wpk Mr. Pass? Nelson Pass That would be rms. You guys are getting closer, but there are some subtleties you've missed, and the circuit will not work properly as shown. GRollins Nelson may speak in terms of peak in passing, but always rates his 'official' output in RMS. D1 won't last very long connected directly to a +17V node. The Gate of Q7 will be biased into full-on conduction. Unfortunate consequences will ensue. This may or may not be what Nelson was referring to... Grey jh6you You are enjoying some subtletis too much . . . Bat man . . . ! ! ! When the Q-point voltage goes up, how I could turn the bottom ccs off . . . ? Damn it . . . Regards jH Nelson Pass quote: Originally posted by jh6you You are enjoying some subtletis too much . . . When the Q-point voltage goes up, how I could turn the bottom ccs off . . . ? There's no such thing as too much enjoyment of subtlety. When the common mode DC value at the output goes positive, you want to increase the current on the bottom ccs. Blues quote: Originally posted by Nelson Pass ...and the circuit will not work properly as shown. :bawling: :bawling: quote: Originally posted by GRollins D1 won't last very long connected directly to a +17V node. Grey D1 is at less than 5V. jh6you Don't make me feel sad, Blues . . . Thanks, Nelson. I hope this will work. Otherwise, soon I will cry like a stupid . . . i . e . like Blues . . . ??? Best Regards jH steenoe quote: Thanks, Nelson. See, JH?? You were wrong, yelling at me;) You really sounds like my ex-wife:D :D Steen:cool: jh6you ex-wife . . . ? Your ex-husband ! ! ! :razz: Regards jH Nelson Pass quote: Originally posted by jh6you I hope this will work. I hate to disappoint you, but it will be unstable. Go ahead and build it, and by the time you discover this, I will have published the circuit and it will be a quick fix. :cool: GRollins Blues, Yep. Last night I saw the 17V labels as referring to the point where the 4.7V Zener attached--today I have a few more seconds and see that they refer to the speaker out. I was thinking that the Zener was faced directly with the 17V (i.e. not biased through the two 36k resistors). Yes, it would register 4.7V...but not for long, as it would draw a lot of current and frazzle in short order. With the resistors, however, it should be safe. My mistake. Man, I hate ambiguous labels. One of the simulators I used to use was persistent in putting one label on top of another if two parts were adjacent. I was never sure which part the label was referring to. I eventually gave up on simulators entirely. After all...everybody knows that if the simulations say an Aleph-X doesn't work that they're right and reality is wrong. Right? Grey P.S.: Am I the only one who's confused about all the marriages and divorces and ex-wives/husbands and such? jh6you I hate to be disappointed . . . Today your :cool: looks like . . . !! I will try to discover all possibilities . . . At the end, I might have to use ropes to anchor them to the ground . . . Building is on-going little by little . . . I will go with p2p . . . I need the quick fix, at high probability . . . Regards jH jh6you I need beer and long sleep . . . I hope no thunder tonight . . . www.firstwatt.com closed and locked the door . . . ? ? ? Regards jH Nelson Pass I suggest you take a look at SOZ Transconductance thread, where GL has posted a schematic which is converging on the actual design. There are still some value and component placement differences. jh6you Me: “When the Q-point voltage goes up, how I could turn the bottom ccs off . . . ?” Nelson: “When the common mode DC value at the output goes positive, you want to increase the current on the bottom ccs.” Confused . . . confused . . . confused . . . X-confused . . . :bawling: Give me a sugar . . . I would stop crying . . . Okay, okay . . . I will increase the current on the bottom ccs and at the same time turn it off. I went to the GL threat and his schematic. Helpful very much . . . And, my resistor values not final either . . . Regards jH jh6you Thinking about the drains' V . . . Thinking about the bottom ccs . . . Thinking about the Nelson's hint . . . Drilling holes . . . All at the same time . . . And, made too many mis-holes . . . It's ok . . . I will use them as air holes connecting inner space to outer world . . . Regards jH jacco vermeulen You intend to construct the F2 just as fast, JH ? You'll have NP sweating in the kitchen, no Jordan gonna save him ! Impressive stuff, enjoying your poetry for the last 15 or so. metalman Current flows through FET's. Form shifts towards the ideal. The journey rewards. Great work jH! Myself, I try to hide my mis-placed holes by making decorative patterns that incorporate them. I then pretend they were intentional. Delusion can be a wonderful tool when employed correctly.:D jh6you jacco, Nelson sweating in the kitchen? . . . too busy to make food. Hmm . . . These days I'm a really good husband and father. They are enjoying nice holiday food in Chinese restaurants . . . hopefully not every day . . . metalman, Thnaks! This Rev.4 will be the last post of my circuit before Nelson shows us his original F1. R19||R20 / c5 / R26||R27 are for stability of drain voltages . . . I estimate that 220uF is big enough to be the by-pass. Nelson, could I apply Aleph current sources instead of the upper constant current sources? Regards jH Nelson Pass quote: Originally posted by jh6you Nelson, could I apply Aleph current sources instead of the upper constant current sources? Yes. Also, I think you meant 47R0 for R19 and 20. :cool: jh6you Yes . . . Thanks about the resistors, indeed . . . Today your :cool: looks very cute . . . :) I change mind . . . One more schematic, Rev.4.1 . . . I will have Aleph curent sources . . . Further discussion will refer to this Rev.4.1 or post #100 . . . It resembles my X-Zen V2 . . . Which I like very much . . . Would like to give a first name to this F1 . . . Aleph F1 . . . ? Of course, the family name is Pass . . . Best Regards jH

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