Hiraga : yet another design

[martinduchesne]

Hi everyone,

Been a reader of this forum for a while, newly member. It's my first post here so please be gentle (hmmm that sounded weird). Bought a 15w hiraga kit from jims audio on ebay with NJW0302G / NJW0281G transistors. Yeah, that was the easy part.

Now for something completely different : the power supply. But before i put my soldering skills to work, i just need some validation from more expert sources just to know that i'm not missing something before i begin. So the PS would look like :

250VA toroidal Tsfo 18-0-18 secondary
25A rect. bridge
1x 68,000uF 25v first stage
1R 15W
2x 68,000 second stage
2,2 uF mkp

So... Am i totally off-track or in the ball park


If you need more infos , i'll gladly add it.
thanks again

 

[fatbattery]

Welcome mate. I cant help much other then that but I look forward to following your project as I am too wanting to build a pair to drive my jbl 2226H woofers in the bass of my horn set up. I usually build tubes but I think these amps will be far more affordable. I am sure if you search you will find more posts on this very old design but your build is well worthy of a new thread if you are going to document the project right through start to finish good luck!. as an after thought. Perhaps too much heat sink-age will be about enough.

 

[42001]

Hi martinduchesne,

I finished my Hiraga 30Watts a month ago. I used a PSU from Per-Anders Sjostrom. Check out his webshop and the design of his PSU: SPS01. This PSU is perfect. If you follow those lines you'll be more than OK.

Sjoerd

 

[martinduchesne]

thanks for your reply,

my power supply looks like (per rails)
toroidal tx 15v secondary
retifiier
1 x 10,000uf caps
1R 25W
2 x 10,000 caps
2.2uf
approx 18VDC out to amplifier circuit



just waiting for my casing to assemble. Will post pictures when done with specs and etc...

 

[Telstar]

You downsized the reservoir pretty much, why?
Think about a cap-multiplier 🙂

 

[martinduchesne]

Sorry i rushed the previous description.

My PSU design is loosly based on danw1million super class-a amplifier on diyaudioprojects with a lower output voltage. I think he "overkilled" the capacitor bank. I was also inspired by TNT-Audio PSU design course to calculate my capacitor bank needs and transformer power. Had a great deal on 2x 120VA toroidal transformers on newark.

So...one transformer for each channel. One channel shown :

An externally hosted image should be here but it was not working when we last tested it.

For the amp section i used jim's audio on ebay kit. The supplier suggests a +-18V PSU output to feed the amp section. I have between 18-19V with my PSU.

15W Pure Sound Class A Amplifer Kit Hiraga | eBay

Any comments on this supplier ?

thanks

 

[iaxxaxxai]

The original 8w Le Monstre asks for something like a minimum of 650,000uF of capacity for its supply. You can read the original articles here: The Class-A Amplifier Site - Jean Hiraga Index
I agree that is a crazy amount of capacitance, but it appears to be necessary for it to sound its best. I will be building one of these soon too, and I plan to use a capacitance multiplier for mine. Something along these lines: Capacitance Multiplier Power Supply Filter

 

[martinduchesne]

I tried something like the Hiraga PSU. See bottom of page : The Class-A Amplifier Site - Hiraga 'The Monster'

Instead i used my 10,000uF caps (not 68,000uF) and 7.5R 20W (not 8R 10W). I could cook bacon on the resistors.

I dont wanna use screw type caps. Do you think those would make a good choice ?

ECE-T1EP683EA Panasonic Electronic Components | Mouser

Thanks