Aksa Lender P-mos Hybrid Aleph (ALPHA) Class A Amp GB

[xrk971]

Another Alpha amp in the family:

Alpha Nirvana 39w 8ohm Class A Amp

 

[zman01]

X,

A very interesting project - a big thank you to Hugh, and we shall be cheering you to get the first build done. 39 watts of single ended Class A power from +/-27V rails sounds very attractive!

 

[aljordan]

c102Regarding the C102 / C1021 / C1020 / C1022 area of the circuit board, can someone explain what is needed or intended here?

I *think* the following

If someone used this elecrolytic in C102 -
C102 555-RFS35V100ME3#5 RFS-35V100ME3#5 Aluminum Electrolytic Capacitors - Leaded 10uF 35V 20% Audio SILMIC II
- then C1022 is intended for a bypass cap of this:
C1020 Bypass 871-B32523Q1225K B32523Q1225K000 22.5mm LS Film Capacitors 2.2uF 100volts 10%

If someone used this filter cap in C1020 -
C1020 (alternate) 75-MKP1848610914P2 MKP1848610914P2 Film Capacitors 10uF 1100volt 5% 2pin 37.5mm LS
- then nothing would go any where else.

Am I correct so far? If not, what do I have wrong?

What I can't understand is why the following is listed on the BOM for C1022, as there is nothing that takes 15mm lead spacing in this area of the circuit board:
C1022 871-B32672P6105K B32672P6105K Film Capacitors 1.0uF 10% 630Vdc MKP PFC, LS 15MM

Thanks in advance for helping me clear this up.
Alan

 

[xrk971]

Aljordan,
Those caps are all various options for one, the various holes are to allow you to use just about any size input coupling cap. The little electrolytic cap probably would be used all by itself. Or perhaps. Smaller C1022 as bypass.

If you want my opinion, just put a 4.7uF MKP there and you are good to go. A 10uF Silmic II is actually superb sounding. If you use a 10uF cap, you won’t have any questions about whether or not you are getting deep bass extension.

 

[Kokanee]

If you are looking for a set of Alpha 20 pcb's ( I have 3) & Alpha BB pcbs (I have 1), please check the Swap Meet forum under thread Class A pcb's. Good prices. X gave me permission to post here.

Regards

 

[ebomb321]

Hi all,

I'm mid 20 build and was curious if there was a through hole option for C105 and C113 "581-12061A180FAT2A 12061A180FAT2A Multilayer Ceramic Capacitors MLCC - SMD/SMT 100V 18pF C0G 1206 1%" from the BOM.

Thanks!

 

[xrk971]

Yes, I think there is a TH silver mica cap that can go there.

 

[ebomb321]

Yes, I think there is a TH silver mica cap that can go there.

thanks! Something like this?

https://www.mouser.com/ProductDetail/Cornell-Dubilier-CDE/CD5CC180DO3F?qs=FKrQhPEeH%2B4YaXtVQx71Gw==
is this in the audio path?

 

[xrk971]

Yes that’s good and it is one of the most critical parts in the audio path. A bad cap here can ruin the sound.

 

[ebomb321]

thank you, would the Mica degrade the signal over the MLCC?

 

[ebomb321]

also, would 22pf be the way to go if im going to run 4ohm? Ive been following the 1.35amp bias schematic.

Thank you All!

 

[xrk971]

Silver Mica is actually the “best”. If what 4ohm builders are using then that is good.

 

[ebomb321]

Silver Mica is actually the “best”. If what 4ohm builders are using then that is good.

Thanks!

I don't know if that's what people are using. I read that in your thread/op in the technical thread.

I'll test with the standard 1.35amp schematic specs and see what happens

 

[ebomb321]

Hi All, Im having an issue fitting C1021 on the board. It's the 250v 10uf 37.5mm from the BOM, but see attached. I'm not sure how to fit this.

I could move c102 to the bottom of the board, but I think C1022 would still be in the way.

Am I missing something?

Thanks in advance!

 

[Vunce]

C102 has four capacitor options, only one cap is needed. Pick one 😉

 

[ebomb321]

C102 has four capacitor options, only one cap is needed. Pick one 😉

Thank you! Sounds silly, but being in the audio path, what would be the best option (being that I have all 4 from the BOM 😁)

 

[Vunce]

Check out post# 244.

 

[ebomb321]

Check out post# 244.

🤦Thank you again. I'm getting super excited going to power this up tomorrow 😃

 

[Vunce]

Same for C105/106 and C113/114.
Pick one style per location.

Happy Power-Up tomorrow 👍

 

[nicoch58]

Thank you! Sounds silly, but being in the audio path, what would be the best option (being that I have all 4 from the BOM 😁)

the best option is what you will like better ...is like a cooking recipe ...try some