Ono semi substitutions and other Q's

[sbear]

Well everybody, I am almost done sourcing all the parts for an Aleph-Ono, but I have a few very specific questions I can't seem to find answers for, or incomplete answers.

2sk170- There has been some debate as to the designation BL, GR, or V. Can someone confirm which "color" is correct? Or does it matter? Can I sub anything else?

2sk389- same Q as above- BL, GR, V, or does it matter? Subs?

2sc1844/2sa991- These are somewhat difficult to get, but they appear to be somewhat of a "generic" part. Are the ztx450/ztx550 an appropriate substitution throughout the circuit, or are there better substitutions?

The RIAA filter, (C4,5,6 and R8,9) any advice as to part choices here? Especially for the caps? Someone has mentioned teflon, others polystyrene, others polypropylene? Also, how precise do R8,9 need to be-1%,2%, 0.1%, does it matter?

These are the only parts I haven't decided on. As soon as I get these figured out (and I get my tax return back) It's time to build!

Thanks.

[wuffwaff]

Hi,

for the 2sk170 you´ll need the GR. Otherwise the current will be too high and you will have a too big voltage drop over the drain resistor. The alternative is to change the source resistors or not to use the high gain setting (76dB). I used BL specs and changed the source resistors a bit. I also disabled the high gain setting wich is normally not needed.

The 2sk389 is not critical as it is fed by a current source at 2mA Here you could probaly use a GR or BL

You can use BC550c/560c or the ztx450/550 watch out if the pins are the same

For C4/5/6 I used ERO MKP 1%, R8 and R9 1%. It does matter how precise but 1% should be enough.

I´ve got a list of the precise parts I´ve used. If you need it you can sent me an email.

William

[sbear]

Thanks wuff, I don't think it is ERO caps are easily available in the US, so I think I will just go with some panasonic polypropylene film. (They were the only decent 1% caps available at the big supply houses here) I did find some 5% polystyrene caps, but I can't find them with a better tolerance. I might try them anyway to see how they sound. Thanks for the info on the FET's; GR it is.
I would like to see your parts list just to see how ours differ.

[wuffwaff]

just sent me an email and I will return the list.

William