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Old 4th April 2011, 03:45 AM   #491
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Hi Al,

Sounds like a good idea unfortunately I cant take you up on your offer at the moment (sadly), With a 9 month old son and I just started a new job i don't have much time for new projects I have too many happening at once !

-Dan
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Old 4th April 2011, 07:46 AM   #492
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Quote:
Originally Posted by danieljw View Post
Hi Al,

Sounds like a good idea unfortunately I cant take you up on your offer at the moment (sadly), With a 9 month old son and I just started a new job i don't have much time for new projects I have too many happening at once !

-Dan
No problem Dan, have fun with your son and luck with your job!
albert
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Old 6th April 2011, 07:57 PM   #493
earless is offline earless  United States
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hello all. i need a bit of help since i think my problems have to do with inexperience. i built the hiraga 20 watt using the boards from diy world in germany. the left channel works well but the left has much less gain and major distortion. i am getting 22 volts positive and negative out of the power supply, but when i connect the speaker to the left channel the positive goes down to 19 volts. any advice on where to take it from here other than to chuck everything out and try fishing?
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Old 7th April 2011, 05:16 AM   #494
masag1 is offline masag1  Germany
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Originally Posted by earless View Post
hello all. i need a bit of help since i think my problems have to do with inexperience. i built the hiraga 20 watt using the boards from diy world in germany. the left channel works well but the left has much less gain and major distortion. i am getting 22 volts positive and negative out of the power supply, but when i connect the speaker to the left channel the positive goes down to 19 volts. any advice on where to take it from here other than to chuck everything out and try fishing?
Did you check swinging with your oszilloscope?

Checked solder joints and correct parts on board?

Regards

Sam
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Old 7th April 2011, 08:59 AM   #495
AndrewT is offline AndrewT  Scotland
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have you measured output offset?
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Old 7th April 2011, 09:30 AM   #496
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Hi Earless,
a good way to find out what is wrong without being scared of smoke, is to use a 10 ohm resistor instead of the 0,33 ohm resistor. The current to the output transistors drops to some 55 mA. Devices will not get hot. But the DC working position remains the same. You don't have to attach a load (it is loaded already by 300 ohms feedback).

Then look how the DC midpoint reacts to changing the cursor position.

It looks like there is imbalance in the both sides (positive and negative).
Test to see if the voltage over the 1k5 resistors is the same positive and negative; I suspect some error will show up.

(Don't worry. I have had similar problems. Mostly having devices plugged in the wrong way... )
albert
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Old 7th April 2011, 12:58 PM   #497
earless is offline earless  United States
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hello masag1, albert. and triode_al. many thanks for your reply. i will follow your suggestions and see what happens.
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Old 15th May 2011, 04:46 PM   #498
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Though long ago thread, I agree to rmgvs posting. I also did another build with the cheap replacement transistors and was amazed what came out. So the idea / layout of this simple amp must be very good!
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Old 10th August 2011, 11:42 PM   #499
cjkpkg is offline cjkpkg  United States
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Well,

I have been itching to build something lately and I just received my transistors based upon Dan's schematic.

I have a spare 18V dual secondary 300VA xformer around. I plan to P2P a PSU using dual rectifiers and probably 4X39,000 or 4X47,000 if budget allows based on what I have done for some Pass amps I have built. Not that I want to go cheap but this combination has worked well in 3 other amps I have built.

Chassis will be a HiFi2000 type with sufficient heatsinks similar specs to what I used for my F5.

I have the board layout complete based very much upon the original schematic. I plan to etch my own boards maybe this weekend.

I look forward to putting this into the listening rotation!
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Old 12th August 2011, 10:07 AM   #500
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Originally Posted by gaborbela View Post
Hello
Did someone ever used these schematic .
It is very interesting with those LEDs and the extra par transistor ..
I use the orig.schematic can these be better than that ?
Any comment on these please .
Probably I will try these interesting schematic with those mods.
Greets
Hi Gaborbela,
How has things followed up with this implementation, I saw you had a PCB made of Tadiams' posting.
hiraga le classe a cascode schema.jpg
I am interested in this version with cascode.
How did it materialise?
albert
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