Got me plenty of those and actually dont know what to do with them
My gut says that no mater how i operate them , they will never beat the 1302-3281 combo .
so ok got a secondary set of 2way speakers that i would like to operate in reality those are sensitive 30W real power speakers so power of the amp is not the issue .... one pair of those will happily produce 60 W ...
so the idea is to go for something diferent How about a tube mosfet combo and highly biased ?
has anyone seen a schematic like that that operates with these transistors ?
if so please let me know
Other suggestions are also welcome but still i think what ever this should be in high bias
My gut says that no mater how i operate them , they will never beat the 1302-3281 combo .
so ok got a secondary set of 2way speakers that i would like to operate in reality those are sensitive 30W real power speakers so power of the amp is not the issue .... one pair of those will happily produce 60 W ...
so the idea is to go for something diferent How about a tube mosfet combo and highly biased ?
has anyone seen a schematic like that that operates with these transistors ?
if so please let me know
Other suggestions are also welcome but still i think what ever this should be in high bias
Ι am very familiar with those people been repairing some machines from them ...They always been very friendly ,detailed and helpful people when it comes to service ...
i love the way they are made BTH i listen to their sound like the 3150 and i think i listen to a prefect flat line of no interest
similar topology AND OUTPUT was the the Sanyo plus 55 which sounds horrible and the word is not enough
been listening also one Accuphase that is J50+ K 135 but only one and that is some 10 years ago and i think that sounded much sweeter than the above
the Hitachi HMA series with those outpouts had the mosto decent result but no where near a 3281 +1302 ...
Comparison makes some sense because all the above circuits are typical class AB regardless if some of them are just a bit higher ....
been there already it doesnt fit my taste I will have to look for something that is well biased
Arrgh...
1302+3281 anyway can't ever touch the sky of K50+J135.
No, no high bias. 50+135 is a lateral mosfets and have very pretty thermally stable point near 100 ma bias current.
What complexity would you prefer?
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I have tried to improve the DH-200 sound but only succeeded marginally thus I quit and concentrated on designs with different parameters objectives.
P101 sound is not my cup of tea….
Goldmund Telos is good but not enough for my taste.
You should try something very different than the standard blameless or such type of designs…
Based on my humble experience with these transistors - I have used lateral mosfet designs since about 20 years - you can get a very good sound with high bias (ex: push-pull class A), CFA topology (like Accuphase) , low overall feedback, no or extremely small degeneration on mosfet, and good drive current. Since you do not need high power a 20-25W rms class A can be a good candidate….
Fab
P101 sound is not my cup of tea….
Goldmund Telos is good but not enough for my taste.
You should try something very different than the standard blameless or such type of designs…
Based on my humble experience with these transistors - I have used lateral mosfet designs since about 20 years - you can get a very good sound with high bias (ex: push-pull class A), CFA topology (like Accuphase) , low overall feedback, no or extremely small degeneration on mosfet, and good drive current. Since you do not need high power a 20-25W rms class A can be a good candidate….
Fab
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Out of my experience I'd recommend the ELEKTOR Crescendo. My build sounds fine, is stable and beefy. With 7 V higher rail voltages for the small signal and driver sections, power output will even be almost twice the original specs.
Anyway, I know of some with other experiences
.
Best regards!
Anyway, I know of some with other experiences
.Best regards!
Any type of mosfet power amplifiers needs around 100 mA bias current through the output devices to sound at its best. Unfortunately, around 1980 when these lateral mosfets were still new and popular, typical magazine projects specified mostly quite low bias levels, perhaps because handling excess heat is expensive, awkward and not always acceptable, particularly in small homes and warm climates.
Almost every lateral mosfet amplifier design was based on Hitachi's application note so here's a useful extract: http://www.cma4ch.org/chemo/ftp/Hitachi-power-Mos-Fet-application-note.pdf
To be fair, the app. note does indicate a bias current of 100mA was used for testing THD of the basic 50W design example(fig.8.7) but most designs that appeared as amateur projects, sounded a bit dry and harsh in the home, due mostly to opting for a low bias - even less than 50mA. Any greater heat output than typical of BJTs likely meant being expensive or unpopular but the resulting compromise also meant that the designs and the mosfets by association, would fail to gain the acceptance of critical listeners. It seems the magazine staff weren't too concerned about that, 40 years ago.
Almost every lateral mosfet amplifier design was based on Hitachi's application note so here's a useful extract: http://www.cma4ch.org/chemo/ftp/Hitachi-power-Mos-Fet-application-note.pdf
To be fair, the app. note does indicate a bias current of 100mA was used for testing THD of the basic 50W design example(fig.8.7) but most designs that appeared as amateur projects, sounded a bit dry and harsh in the home, due mostly to opting for a low bias - even less than 50mA. Any greater heat output than typical of BJTs likely meant being expensive or unpopular but the resulting compromise also meant that the designs and the mosfets by association, would fail to gain the acceptance of critical listeners. It seems the magazine staff weren't too concerned about that, 40 years ago.
Out of my experience I'd recommend the ELEKTOR Crescendo. My build sounds fine, is stable and beefy. With 7 V higher rail voltages for the small signal and driver sections, power output will even be almost twice the original specs.
Anyway, I know of some with other experiences
Best regards!
Sorry but saying that the power will be twice only by raising front end rail voltage by 7v will double the power makes your opinion non valid ...
raising rails for the front ends will only result milder clipping when outpout stage is on clip conditions and if front end rails are stabilized also you get a bit better sound
Most of Giesberts designs are extremely poor when it comes to thermals and most of his designs are based on perfect small signal transistor which is a thing that doesnt exist ....you can have a BC 557 with hfe of 100 and you can have the next 557 with hfe 600 ( which is wrong )
Most of his big designs needed adititions , patches and mods to remain stable
Your estimation is wrong and personaly i wouldnt construct LM3886 under the name of Giesberts
What orders of such a "plenty"? Tens/dozens?
Is it worth to route a board for those TO-3 case?
Well, I've measured it: With +/- 77 Vdc at the front end rails and +/- 70 Vdc at the power rails my build's output power right at the onset of clipping is 330 W @ 4 ohms. Elektor says 180 W with +/-70 Vdc rails.
Best regards!
He-he!
But i said very good things about your j50/k135!
Try attached.
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