I think this post still gets many people confused about whether the Fairchild JFETs can replace the Toshibas
http://www.diyaudio.com/forums/pass-labs/121228-f5-power-amplifier-514.html#post3340644
http://www.diyaudio.com/forums/pass-labs/121228-f5-power-amplifier-514.html#post3340644
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It's one thing to keep silent about the circuit, it's another to tease and alienate someone. Not very cool. 
Nag.
Read the bloody thread if you want to build something that approaches the design of the F7.
I know it's a lot of work but it's not fair to expect Papa to give you the official circuit diagram.
If you're not prepared to put the effort in to read the thread then build an F5, F6, or Aleph J.
Read the bloody thread if you want to build something that approaches the design of the F7.
I know it's a lot of work but it's not fair to expect Papa to give you the official circuit diagram.
If you're not prepared to put the effort in to read the thread then build an F5, F6, or Aleph J.
sorry boyz , but it really is becoming tiresome ...... writing again and again that there is no substitution for Toshiba/LSK complementary pair , if one want's impeccable performance from amp , as Papa made it .
there are candidates for sub , when complementary pair is not used , and when JFet in question is biased through CCS , as in Aleph J and , say , J2 ;
toob boyz are somewhat more calm regarding substitutes - if any of them start dreaming about 300B , he will try finding cheapest or best bang for the buck 300B , but he'll never try harassing people asking how to make 300B amp with 6A3
it is something in the air these days , definitely ; ppl are not reading threads , not reading half page long replies on specific questions
on the other hand , world is full with amps without Toshiba JFets ........ and even mosfets
read attached ; written more than 10 years ago ..... so - for 10 years I'm helped by ppl to change things ....... I'm helping ppl to change things ........ and also helping them what not to change , at least much as I am able and capable ....... and that's example where something can be changed for better , even in bean-counter's way
damn 50 greenies is less than 10% of parts price , as EUVL said the other day ....... for ooomphteenth time , and - even if you save these 50 greenies , performance drop is much more than 10%
there are candidates for sub , when complementary pair is not used , and when JFet in question is biased through CCS , as in Aleph J and , say , J2 ;
toob boyz are somewhat more calm regarding substitutes - if any of them start dreaming about 300B , he will try finding cheapest or best bang for the buck 300B , but he'll never try harassing people asking how to make 300B amp with 6A3
it is something in the air these days , definitely ; ppl are not reading threads , not reading half page long replies on specific questions
on the other hand , world is full with amps without Toshiba JFets ........ and even mosfets
read attached ; written more than 10 years ago ..... so - for 10 years I'm helped by ppl to change things ....... I'm helping ppl to change things ........ and also helping them what not to change , at least much as I am able and capable ....... and that's example where something can be changed for better , even in bean-counter's way
damn 50 greenies is less than 10% of parts price , as EUVL said the other day ....... for ooomphteenth time , and - even if you save these 50 greenies , performance drop is much more than 10%
Hmmm, tiresome eh? Wait till the Pass B5, LXmini+2 xover and the likes are published. It's gonna become really interesting. Even with the 250k jfet parts "brought into inventory". We have plenty of both hoarders and misers. The hoarders wil finish them in no time. The misers and late comers will joyfully pester 24/7.😱
Perhaps something sticky should be prepared?
Well said. The Aleph 30 uses BJT's and one of the major improvements of the Aleph J are j-fets for the front end. With research you can find alternative circuits not using J-fets but why waste time.
Oh, how time flies... I had a very positive impression about Babo and I was very sad when he got sick and soon passed away 🙁. I remember when he was buggin' Zen for advices, seems like it was yesterday...
Sorry for OT...
Sorry for OT...
It's one thing to keep silent about the circuit, it's another to tease and alienate someone. Not very cool.
Agree 100%. Even resident consultants cannot expect that everyone has to act as per their recipes. And if they don't so what? Some are following, others not, and it's in their full power to do so, their decision. With all pros and cons.
There is no reason to feel bad about that.
Apart that...:
http://www.diyaudio.com/forums/pass-labs/121228-f5-power-amplifier-1285.html#post3340644
Hi Guys,
Actually the schematic is provided in below thread by Papa.
Now I added Toshiba FET's. Actually I am not expecting F7 but simple circuit which can produce 10watts.
Recommendation for 5-10W amp.
Can any one have good experience in First watt amps can suggect R1,R2,R3,R4,P1,P2,P3 and V+,V- for 10watts.
Thanks,
Nag.
Actually the schematic is provided in below thread by Papa.
Now I added Toshiba FET's. Actually I am not expecting F7 but simple circuit which can produce 10watts.
Recommendation for 5-10W amp.
Can any one have good experience in First watt amps can suggect R1,R2,R3,R4,P1,P2,P3 and V+,V- for 10watts.
Thanks,
Nag.
Attachments
not feeling bad ..... just claiming right to make jokes with other resident
regarding Papa's statement , no dispute (of course) from Mighty Moi , but I still insist on said - performance of amp will suffer more than 10%
5 years ago , I bought 500pcs of J309 and 500pcs of J271 ...... quantity which will certainly outlast me , but I can't use them everywhere
regarding clever approach , just review Babo's files , fill in the blanks and that's it
use whatever you want ...... I'm just saying that I had my share of investigating needless hopes outcomes ..... and probably I'm not yet finished doing that
regarding Papa's statement , no dispute (of course) from Mighty Moi , but I still insist on said - performance of amp will suffer more than 10%
5 years ago , I bought 500pcs of J309 and 500pcs of J271 ...... quantity which will certainly outlast me , but I can't use them everywhere
regarding clever approach , just review Babo's files , fill in the blanks and that's it
use whatever you want ...... I'm just saying that I had my share of investigating needless hopes outcomes ..... and probably I'm not yet finished doing that
you already got it ;
it isn't F7 , nor F5
if you are not able to decipher and properly execute F7 , then just make smallish F5 , maybe with smaller IRF (510/9510 or similar) in output ..... if you insist on laterals - make Plantefeve's Buzquito/Mosqito or something
set Iq by heatsinks and PSU you have on hand
This is all very pleasing for me, it is a subject of much frustration that his Passfulness has been pumping out the "best ever yet" using unobtainiun (SITs) to the late arrives like me. But now, oh joy, complementary laterals... Ones still in production no less, that you can buy. Marvelous. In fact the laterals have been on my radar for some time, in amps I respect, or are loved by mr 6moon, (correct me if I am wrong) for example, the Spectral, the Backoon, and the Goldmund- Job etc. Also this particular (output) configuration is one I have had in mind for some time as being most likely to be the best sounding, but have been troubled a little by the damping factor done by feedback alone. So positive current feedback, yipee. It is something I have been playing with under different names, but this is nice simple to grasp. The question now, given limited time resource, to build something a bit like an F7, or continue with my hybrid 2x P channel, and one triode-pentode tube amp..... I think the current feedback could be a helpful ingredient and it will be fun trying to graft it in..
People here would tell you to build both.
A note about PCF, it was explored in the 50's and abandoned, as far as I
can make out because of the difficulties when applied to amplifiers with
limited bandwidth due to output transformers and/or capacitors. The
phase shift involved makes it behave differently than with a DC coupled
wide band circuit.
If you are thinking about trying this with a tube amp, you will want to be
aware of this as a limitation as to the amounts of PCF you can apply.
A note about PCF, it was explored in the 50's and abandoned, as far as I
can make out because of the difficulties when applied to amplifiers with
limited bandwidth due to output transformers and/or capacitors. The
phase shift involved makes it behave differently than with a DC coupled
wide band circuit.
If you are thinking about trying this with a tube amp, you will want to be
aware of this as a limitation as to the amounts of PCF you can apply.
Recently find DIY tube amp with NFB = 5.5 dB and use PFB indeed.
r-tec1804_(04)6BM8(T)pp-power-amp(3)_AkiI.pdf - Google Drive
A commentaires about positive feedback on this schematic ? 🙂
r-tec1804_(04)6BM8(T)pp-power-amp(3)_AkiI.pdf - Google Drive
A commentaires about positive feedback on this schematic ? 🙂
