Ain't exactly pretty,
Ain't exactly small... 😀
V2 with a pair of Sikorels:
The honeymon isn't over yet. This is a fabulous sounding amplifier!
Dave, the most important is that the honeymoon continues.
If someone is interested to build the Mosfet amplifier, I have some PCBs available.
Just send me a PM.
If someone is interested to build the Mosfet amplifier, I have some PCBs available.
Just send me a PM.
After an interest that I had from some friends, I have redesigned the PCB making some minor modifications mostly concerning the original Jfet used for the current source of the input differential pair which is now obsolete. Instead I used a J176.
I have ordered a new quantity of PCBs and built a couple of new amplifiers.
Some of the PCBs left in my stock.
If someone is interested to build this nice MOSFET power amplifier, the price for a pair of PCBs is 34 Euros (post is including).
I have ordered a new quantity of PCBs and built a couple of new amplifiers.
Some of the PCBs left in my stock.
If someone is interested to build this nice MOSFET power amplifier, the price for a pair of PCBs is 34 Euros (post is including).
This is a Panasonic Polypropylene 3.3 uF Capacitor (ECW-F2W335JAQ).
What better quality would you propose ?
What better quality would you propose ?
WIMA is better but my favorite is the old Philips. Oh, probably 4.7uF is better. Overrated in RC is often audible. There is also Philips MKC in rectangular shape but it doesn't sound as good as this axial model.
Attachments
Last edited:
The PCB dimensions are the same as in previous version :167 mm X 57 mm.
It is a 1.6mm, double-sided PCB.
It is a 1.6mm, double-sided PCB.
Thanks for the PCBs, they arrived safe and sound and look good. Don't know when I'll get chance to start building, but it's third in a queue of three, and I'm not quick.
But, eventually, I'll post here when I have something that works or if I bork it and need help...
But, eventually, I'll post here when I have something that works or if I bork it and need help...
You should not put this amp in "Rebuilt of Linsley Hood Mosfet amplifier from Wireless World 1982" as it has no similarity to it just uses lateral for output. Better open new thread for it.
By the way if you want to keep low DC offset at the output you need to have
R6=R5+R27 and with matched LTP no need for DC offset trimmer
The bias trimmer should be between base and emitter not base and collector!
Last edited:
This doesn't appear to sink in probably because of the umpteen audio websites advising those posters who want to build actual JLH designed power amplifiers to use LATERAL mosfets .
As someone who not only bought every edition of EW/WW in that era including all John,s publications in other UK audio magazines including ETI-Today well know to UK electronics builders I completely fail to understand why after John made a big-big point of saying he used VERTICAL mosfets recommending Hitachi .
He said do NOT use Lateral as they require different conditions --it seems to be if you talk about something long enough everybody believes its "true" --except of course me who built all John,s designs and yes modified some at a later date .
I am at present trying to dig up the UK edition of the magazine he made this perfectly plain/clear in so to squash the mis-held believe that John used LATERAL mosfets in his designs in the 1980,s designs --he did not !
I wont be holding my breath as John,s designs have been copied worldwide and "modified " --never once have I used Lateral mosfets in them and yes --- I still have the original 1980,s VERTICAL mosfets used on his designs as well as a few spares from that era .
John also went to great length to show the superior audio quality of them but of course that "upset " D.Self who spent several editions of EW trying to rubbish them and promote his BJT output designs .
As someone who not only bought every edition of EW/WW in that era including all John,s publications in other UK audio magazines including ETI-Today well know to UK electronics builders I completely fail to understand why after John made a big-big point of saying he used VERTICAL mosfets recommending Hitachi .
He said do NOT use Lateral as they require different conditions --it seems to be if you talk about something long enough everybody believes its "true" --except of course me who built all John,s designs and yes modified some at a later date .
I am at present trying to dig up the UK edition of the magazine he made this perfectly plain/clear in so to squash the mis-held believe that John used LATERAL mosfets in his designs in the 1980,s designs --he did not !
I wont be holding my breath as John,s designs have been copied worldwide and "modified " --never once have I used Lateral mosfets in them and yes --- I still have the original 1980,s VERTICAL mosfets used on his designs as well as a few spares from that era .
John also went to great length to show the superior audio quality of them but of course that "upset " D.Self who spent several editions of EW trying to rubbish them and promote his BJT output designs .
Why you say that ?
It is the same amplifier as published in Wireless World August 1982, figure 14.
The only change I have made is that I used different type transistors in the driver stages.
Last edited:
While I am looking for the original JLH instructions here is just one website -
2SK134 & 2SJ49 MOSFET replacement advice | All About Circuits
Vertical mosfets arrived on the market in 1969-- I cannot expand your thumbnail but if the output mosfets are the original 2SK134/2SJ49 then they are vertical no matter how much Exicon advertise and promote their lateral mosfets as "replacements " .
2SK134 & 2SJ49 MOSFET replacement advice | All About Circuits
Vertical mosfets arrived on the market in 1969-- I cannot expand your thumbnail but if the output mosfets are the original 2SK134/2SJ49 then they are vertical no matter how much Exicon advertise and promote their lateral mosfets as "replacements " .
Sorry I mixed it with an other JLH famous mosfet amp, where he used same wrong position for bias trimmer, but have used R18 = R1+R2 (allmost).
If you put that bias trimmer between base and collector in case the trimer failed the bias current increase to much and burn output laterals, if it's between base and emitter the bias current drops to zero.
If you put that bias trimmer between base and collector in case the trimer failed the bias current increase to much and burn output laterals, if it's between base and emitter the bias current drops to zero.
