AV1000 building

[Daniel(Del)]

Hi all!

I intend to start building 2 AV1000 boards I bought from Mr. Holton long ago. Please, don't ask me for PCB layout, I don't have it and it is his intellectual property.

I need help to find the actual values of some components that diverge in the schematic and in the bill of materials. Other components also bring options and I'd like to figure the best choice.

C10) 100µF bipolar at schematic but normal electrolytic at bill of materials.
C11) 220nF at schematic, 220nF up to 1µF at BoM and 100nF at component inventory.
Q11) 2SC4793 at schematic and IRF610 at BoM.
Q12) 2SA1837 at schematic and IRF9610 at BoM.
Q7) 2SC4793 or MJE340 at schematic. BoM says only 2SC4793.
Q8) IRF610 or 2SC4793. BoM says only IRF610.
R18) 100R at schematic but 150R at BoM.
The divergences are also highlighted on the schematic.

If you guys have a better option of transistors to avoid the Toshibas, that are also present on Q1,Q2,Q5,Q6,Q9 and Q10, I'd really appreciate it, since original devices are hard to find and I'd like to buy everything from Digikey preferably. Also, suggestions for different component values and capacitor types are also welcome. I'd be very grateful if you could take a look at the whole schematic and give any suggestions as long as I can keep the PCB I already own.

Finally, I intend to run the amplifier at +/- 75VDC so that it's possible to drive 2R loads if ever needed.

Thanks very much for the attention and a happy new year!
Cheers
Daniel

[Daniel(Del)]

Is it worth replacing IRFP9240/IRFP240 by the 2SJ201/2SK1530 pair when it comes to sound quality?

[Daniel(Del)]

Guys!

Can someone explain me the role of C12..C31 on the design above?

Thanks in advance
Daniel

[sakis]

the capacitors 12-13 are only additional filtering for the first stages of the amplifier all the rest are additional reservoir of power but very close to the output transistors ( i presume )

Rule is the bigger the better ...only size will determine what to use and of course rail voltage ..

By the way this is a very risky project.....so much power and absolutely no protection from the amplifier it shelf things like choice of parts matching and so on will play a very critical roll and fail to follow procedures will result to a big cabooooom

c11 is a bias stabilizer and either 100 or 220 will work ok ( i would go for the lower value though )

C6 and C7 cannot be ceramic needs to be at least 500 V capacitor and this will be styroflex /silver mica /or ceramic multilayer

to my understanding this is a big project and will not be easy to finish and operate properly if a first project and or instruments or experience is present

kind regards
sakis

[Daniel(Del)]

Hi Sakis! Thank you for the answer!
What do you think is the problem this design can run into? Thermal runaway? What if I run it with lower rails, say +/- 75 VDC?

Thanks in advance