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Old 10th October 2012, 06:32 AM   #1
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Default Hiraga 30 watt. Advice needed

Hi Folks.
I have just purchased 2 Hiraga 30 watt kits from Jims Audio on ebay,

Hiraga super 30W class A amplifier kit ! | eBay

I also purchased the transistors he sells for these kits, but my question is what power supply etc I need for this.
Reading all the info I can on here and on other websites has left me pretty confused as to the best way to complete this project. Some other builders are using massive caps. Is this the way to go? I need advice on the power pcb. Is there a suitable kit and what transformer would be needed?
Any help would be fantastic.
Thankyou.
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Old 10th October 2012, 07:12 AM   #2
WSJ is offline WSJ  United States
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The 2SA872 is a 90 V device, 80% of 90 should be good for the power supply.
http://datasheet.octopart.com/2SA872...eet-101859.pdf
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Old 13th October 2012, 08:03 AM   #3
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Thank you, but I'm really looking for a suitable pcb kit for the PS, plus reasoning behind the massive caps some circuits are using, and advice on a transformer to compliment the above.
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Old 24th July 2014, 02:20 PM   #4
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Im also confused about the powersupply. I just purcased the torroid from the chematic (500va, 230-2x25v). It was very expensive.
The caps are expensive to. How much is needed?
Im also wonder if I must make it a regulated powersupply. will that affect thesound quality?
And how much fuses are recomended?
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Old 26th July 2014, 10:22 AM   #5
Eldam is offline Eldam  France
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Location: At home, sweet sound home...
And why not a SMPS...

Some simple thoughts :

- big caps like > 40 K uF have small ESR but also a larger low impedance frequency width than smaller caps haven't. I think this is the reason of the big value, also for filtering and big inertia of course. If the soft and good sound of Hiragas' class A are famous, this is certainly one of the reason with the particular choice of the components. I surmise if Supercaps would existed before with such Farads an so low esr with such voltage capacity, Hiraga would probably had tested it. For the first Stage very low ESR should be avoided, but for the second stage of the Pi (reservoir caps) : a very low ESR is better !

- Check the ripple current capability of such caps to find the higher you can : BC, german brands...

- Check if you can source the genuine NOS transitors (metal can ? : there is a reason!)

- For filtering you can go maybe for a Pi if not exist in the kit. Inductance in opposite winding could be ok if can find it with such current (not to be worst than without...). Your major concern if Pi is choosed : first caps smaller or equal uF value in relation to the second caps stage of the Pi. "normal" ESR for the first stage but solid cap : Long Life, higher degrees your money can allow : 105c 125 c if you can ! Second Pi stage : high ripple current & very low ESR large uF value (40 k Uf minimum x the total needed in the genuine shematic).

- for input stage go with a very good quality input cap if exist or if no input trafo : e.g. a MIT RTX or a Riven Paper, Amphom in oil/wax....

But we haven't not to be closed minded : if fast regulated works : go for a fast linear one... then compare, keep the best, and please testimonie after for us !

Wisch you a nice soldering,

regards

Eldam

Last edited by Eldam; 26th July 2014 at 10:34 AM.
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Old 26th July 2014, 12:02 PM   #6
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Quote:
Originally Posted by dominic harper View Post

Reading all the info I can on here and on other websites has left me pretty confused as to the best way to complete this project. Some other builders are using massive caps. Is this the way to go? I need advice on the power pcb. Is there a suitable kit and what transformer would be needed?
Any help would be fantastic.
I would not recommend more than 35-0-35V, absolute max. Make sure you use huge heatsinks, the biggest you can find. Class A generates lots of heat, even at low volume. Some PSU help can be found here.
Cheers,

Jacques
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