JAS - Just Another Sziklai

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#41
CFP output stage

Hi ATAUDIO,

In the past i have done several compound outputstages (CFP) and i have ended up with the attached schematic.
Idling current is more stable because of R3 and R4, the thermal stability is increased but you will lose some headroom.
To minimise crossconduction set the value of R1 and R2 to a value as low as 49 Ohms. I choose 68 Ohm.

best regards,
Piersma
 

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#42
Piersma said:
Hi ATAUDIO,

In the past i have done several compound outputstages (CFP) and i have ended up with the attached schematic.
Idling current is more stable because of R3 and R4, the thermal stability is increased but you will lose some headroom.
To minimise crossconduction set the value of R1 and R2 to a value as low as 49 Ohms. I choose 68 Ohm.

best regards,
Piersma
Click to expand...
Intersting...
How you choose R20 and R23?
Did you want to have some voltage gain or are them there only to reinforce degeneration on driver side?

All the rest is pretty standard.
Thanks a lot
 
#44
thanks for your kind words ataudio

i am sorry to say that i never had the schematic of the specific amp ... stil though i own 4 of these speakers and a spare board ... between me and you it could be much easier to sent you a spare part than trying to hand draw a schematic ..too bussy to do that .

there is no chance ( from time aspect ) that i can do the schematic for you now ... may be after the sumer ..though this is a very ineteresting thread and i will stay tuned .

some information may be found around an amplifier that as presented somewhere here called Joy 200 .. i think alexmm made pcb for it

( by the way should we call the alex mm the absolute pcb designer for the solid state forum (eventhough i dont like none of the pcb he makes) .... too square and all under the same patern .... )

i think that there is already some people that builted the amplifier so may some aditional feedback may flow for this one also ...

for the record and next to your amplifier and the joy 200 i havent meet with any other comercially made sziklai with multiple outs .... may be less than a handfull .... probably cause its not easy to stabilize ...

keep up the good work and lets see how it comes up
 
#46
Commercial CFP amp

Hi AT,

I choose for a solid reinforcement for degeneration on driver side. (R20/R23)
Audiolab has done a commercial amplifier with a CFP output in the past.
(but there are several others too)

regards,
Piersma
 

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#48
sakis said:
ifor the record and next to your amplifier and the joy 200 i havent meet with any other comercially made sziklai with multiple outs .... may be less than a handfull .... probably cause its not easy to stabilize ...

keep up the good work and lets see how it comes up
Click to expand...
You forgot the Nakamiki PA7, Sakis.
And there are also Crown, but they are CFP triples, and that is another story.
 
#52
Tekko said:
Which is better, CFP or Darlington ? I've heard ppl have oscillation problems with this Sziklai topology.
Click to expand...
I belive this is a fruitless question, posed so many times and in so general terms. If you want to pursue it, I strongly invite you to open your own thread, whre I will happily post. Thank you.

BTW, I am on a trip abroad for a while, so I will not follow the thread daily. But be assured, the project, for the few that might be interested, is going on.
 
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