LuFo Amp - 39w SE Class A from 28v Rail

[Ryssen]

Ok thaanks for that,thought it was sommething wrong....

 

[namghiwook]

I have SLB(dual, not 2 x single) PSU with 400VA transformer.
It makes +/-27VDC output without load.
Can I use this +27VDC as power of LUFO?

 

[namghiwook]

I have some M2x IPS (unity gain) boards.
Can I use these as FE of LUFO?

 

[xrk971]

Dual cannot be used with LuFo. Well only the +ve rail. Leave the negative unpopulated.

You need more than unity gain front end. Since LuFo is also unity gain, you need something preferably with 20dB to 28dB gain.

 

[namghiwook]

Thank you!
I use a wayne linestage preamp and will get more gain from it with some mod.
I just want to know that M2x daughter board as FE instead of bypassing.

 

[namghiwook]

These parts below exist in LuFo-BOM-Rev02b-Nov-02-2021 (#756) but I ordered parts with the shared mouser cart by Vunce (#195) already, then I missed these and I must order these additions.

R181, R191 - 100k CMF55_GENERICJPS64, Metal Film Resistors, Axial, Industrial, Precision, CMF55, 250V, 1/2W, 1%
R183, R193 - 20k0 CMF-55+9MM
R184, R194 - 1k0 M64Y203KB40AUDIO, RTRIM64Y
C121, C125, C161, C165 - Mundorf EVO Silver Gold Oil 2.2uF 450V
C122, C162 - 22p ?? or 10µ, 16V, X7R, 1206
C184, C194 - 47µ0 Aluminium electrolytic Capacitor, Series FC, 47µ, 63V

I've select parts for these.

R181, R191 <= 71-CMF55100K00FHEA
R183, R193 <= 71-CMF5520K000FKEK
R184, R194 <= 594-64W102
C184, C194 <= 667-EEU-FC1J470BJ


C121, C125, C161, C165 <= Mundorf EVO Silver Gold Oil 2.2uF 450V are so expensive. Any other recommending parts?
C122, C162 <= 22p ?? or 10µ ?? What is value of this? Could you recommend for this part?

 

[xrk971]

C122/162 is 22pF - use NP0 SMT or alternate silver mica.

Instead of Mundorf use any quality 2.2uF MkP - Wima, Vishay, Audyn, etc.

 

[Vunce]

Namghiwook,
What inductor do you plan on using?

 

[namghiwook]

@xrk971
Thank you so much!

@Vunce
I ordered CH-4.
https://www.mouser.kr/ProductDetail/Bel-Signal-Transformer/CH-4?qs=0/2GmT7MRM9RsVUzZKxOJw==

 

[xrk971]

Interesting choice for a choke. I had not seen this one before but 70mH 4A and 0.6ohm is a good set of values.

 

[namghiwook]

CH-4 choke has been metioned by @von Ah at this post

 

[namghiwook]

Which value of MELF resistor on LU1014d adapter board is proper for Lufo amp?
100ohm or 220ohm ?
@xrk971 has recommended vishay melf 220ohm on this post.

Can I use the LU1014d adapter board with the same resistor value for Lufo Lite amp?
... and also..
Can I use CH-4 choke for Lufo Lite amp?

 

[xrk971]

Either 100 or 220 is fine. I think 100 is nominal value for adapters sent out in LU1014 giveaway.

 

[namghiwook]

Thank you! I wlli order 100ohm MELF resistors.

 

[namghiwook]

Can I use this CH-4 choke as it is?
These values is far from its' own specification ( 600ohms DCR, 70mH )
This LCR meter is cheap one, but this inductance value is so high.

https://www.mouser.kr/ProductDetail/Bel-Signal-Transformer/CH-4?qs=0/2GmT7MRM9RsVUzZKxOJw==
https://www.mouser.kr/datasheet/2/643/ds-st-sc-series-1633535.pdf

 

[namghiwook]

Sorry. mis-typing.
The DCR of CH-4 is 600mOhms on its' specfication.

 

[xrk971]

That works fine. Too high of mH is not a problem. Low 0.6ohm DCR is excellent. Make sure it can handle continuous DC current on 4A range.

 

[namghiwook]

Thank you @xrk971
I don't know how to know that it can handle continuous DC current on 4A range.
Anyway I will go with it.

 

[xrk971]

They usually have a max current rating.

 

[namghiwook]

If continuous current is more important than inductance, CH-6 looks better than CH-4.
Is it right?



CH-4
https://www.mouser.kr/ProductDetail/Bel-Signal-Transformer/CH-4?qs=0/2GmT7MRM9RsVUzZKxOJw==

CH-6
https://www.mouser.kr/ProductDetail/Bel-Signal-Transformer/CH-6?qs=0/2GmT7MRM9L5fKGGIdMww==