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Hiraga 20W class A
Hiraga 20W class A
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Old 1st April 2012, 08:36 AM   #581
triode_al is offline triode_al  Netherlands
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Quote:
Originally Posted by gaborbela View Post
Hello
So you say to use the connection at the mosfet version it was correct. Connect to the ground!? Like the schematic at the post 571?
Please advise if I understand it well. All do I want to go a bit higher PS voltage. About 17V rail voltage but I still do not think that extra 5V will do 5V swing.
Greetings Gabor
Yes, post 571 is correct for this input pair.
But just a tip that with higher power you also use a higher feedback divider (like Hiraga goes to 330 ohm/10 ohms in the 30 W version of Le Classe A).

The interesting part is that in this topology the output FET will have a different punch than in the F5 . . . and will definitely have a lower shoot-over. Good for e.g. electrostats or other complex drivers. (F5 exhibits overshoot at very high frequencies).

That explains my interest.
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Old 1st April 2012, 03:51 PM   #582
gaborbela is offline gaborbela  Canada
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Thank you
Honestly I didn't heard big difference at the Class A with higher resistor on feedback or capacitor on feedback.
Actually I do not like capacitor on feedback on the feedback resistor very much. It get a bit muddy the sound..
If you exchange the 5 or 10W resistor for 0.33 that you can hear it right away. More dynamic, bass etc but the power transistors will get more load-- more heat.
To return to the LeMonstre I like these version. I want to test it.
I purchased the semis but one side they sent me not N type. Huge difference between the N type and with out.
I have to get the right mosfet. Also I prefer the red resistors from Parts Connexion.
I tried before Dale (not bad) Takman (not my cup of tea) but the PRP well balanced resistor (very little color or nothing).. I want to use that.
I never built the F5 but I built the Profet and not bad amp.
One think when we build a simple amp like these very sensitive to the parts what we use done to the wire to.
Thank you
Greetings Gabor
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Old 5th October 2012, 04:11 PM   #583
Rixsta is offline Rixsta  United Kingdom
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Hiraga 20W class A
Hi all
This is my amp here, Fake +/- 21v
Click the image to open in full size.


Amp board, so my question those two variable resistors, what do you think one is dc-offset ? and the other Bias ? but i don't know which one is which.
Click the image to open in full size.
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Last edited by Rixsta; 5th October 2012 at 04:13 PM.
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Old 5th October 2012, 04:51 PM   #584
Rixsta is offline Rixsta  United Kingdom
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Hiraga 20W class A
i ask this as the original does not have 2 potentiometers in....
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Old 5th October 2012, 05:02 PM   #585
stoN_Cold is offline stoN_Cold  Serbia
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Quote:
Originally Posted by Rixsta View Post
Hi all



Amp board, so my question those two variable resistors, what do you think one is dc-offset ? and the other Bias ? but i don't know which one is which.
Closer for input for DC ofset.

Regards zeoN_Rider
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Old 5th October 2012, 05:44 PM   #586
Rixsta is offline Rixsta  United Kingdom
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Hiraga 20W class A
Thanks, i see that i have to adjust both. i presume about 0.5v will give 1amp bias. This is my first Hiraga amp, im used to Nelson Pass amps
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Old 19th December 2012, 02:21 AM   #587
katip is offline katip
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Hi, everybody.
I want to do this project so I'm seach for "jean's hiraga 20w class A" on Google.
I found this pcb (see the picture) Do you think it work for this project?

Click the image to open in full size.

circuit for this pcb

Click the image to open in full size.

With best regards
Katip
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Old 2nd July 2013, 11:46 AM   #588
Rixsta is offline Rixsta  United Kingdom
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Hiraga 20W class A
Katip, this looks like the version I have which has more capacitors whose function I do not know.
A while back i accidentally shorted something and it blew one of those diodes but that was good it blew the Diode instead of the Outputs.
I have this amplifier already built running from 12vdc step up to -/+ 24vDC ~

Probably going to sell soon as I prefer the F5 amplifier however I could try upgrading the Carbon film resistors to Metal Film before making a decision!

The Hiraga 20w is a very good sounding amp, just think it could be better! atleast my amp..
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Old 9th July 2013, 04:43 PM   #589
Rixsta is offline Rixsta  United Kingdom
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Hiraga 20W class A
I blew a Zener on this amp some time ago, do we know what a good substitute is for one currently ? ill replace all 4. probably upgrade some of the parts, see if it matches F5 and then sell the amp as Ill probably still prefer the F5.

Ive heard BZX85 is a good substitute
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Last edited by Rixsta; 9th July 2013 at 05:03 PM.
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Old 9th July 2013, 10:02 PM   #590
fab is offline fab  Canada
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Hiraga 20W class A
Default Hiraga and F5

I have built both the Hiraga 20w and the F5 but I prefer the Hiraga without any hesitation (at least in my audio set-up). It is true that many versions of Hiraga super class A exist and the result could be different from one implementation to the other... Also I prefer the Hiraga with semi-lateral MOSFET output instead of BJT ( even with the very linear njw3201/njw1302)

Fab

Last edited by fab; 9th July 2013 at 10:06 PM.
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