I found an amplifier kit from Hifidiy.net - a Chinese company supplying DIY audio kits.
HIFIDIY mini-A power amplifier A20 Assembly Instructions
Basically, its a 20W class A amplifier. The kit comes complete with PCBs, components, what looks to be a 200 VA toroidal transformer, 40,000uF in the PSU, heatsinks and a nice, shiny case.
Im living in Japan at the minute and because of the strong yen, this kit would cost very little. (less than 200 pounds in real terms)
I was wondering a few things:
Has anybody built this kit?
Has anybody any experience with hifidiy.net kits in general?
Unfortunately, I cant find a circuit schematic, but does this look like a decent amp for a beginner to build?
Also, Im a bit worried about the lack of proper English instructions - I dont think I'd have to much trouble populating the PCBs and wiring it up, but in the assembly instructions (looks like they used google translator!) theres a section describing what looks like amplifier set up - perhaps setting the bias? The English translation doesnt make any sense! There seems to be more pictures on the Chinese assembly instructions.
HIFIDIYСÐͼ×ÀàA20¹¦·Å×°»ú˵Ã÷(ÕýÔÚ¸üÐÂ, ÓÐÎÊÌâÇë¸úÌù,ÎÒÃÇ»á»ã×Ü) - HIFIDIY ²úÆ·×ÊÁÏרÇø - HIFIDIYÂÛ̳ - Powered by Discuz!
I have some Chinese friends who could, perhaps, help me with the Chinese, although they know nothing about electronics.
The other thing I was wondering, I believe the trans is set for either 115 or 230 V operation - this would suit me as Id need it in 115 V for Japan and 230 for when I move back to UK - would it be just a case of rewiring a couple of leads on the transformer to make the change?
Thanks.
HIFIDIY mini-A power amplifier A20 Assembly Instructions
Basically, its a 20W class A amplifier. The kit comes complete with PCBs, components, what looks to be a 200 VA toroidal transformer, 40,000uF in the PSU, heatsinks and a nice, shiny case.
Im living in Japan at the minute and because of the strong yen, this kit would cost very little. (less than 200 pounds in real terms)
I was wondering a few things:
Has anybody built this kit?
Has anybody any experience with hifidiy.net kits in general?
Unfortunately, I cant find a circuit schematic, but does this look like a decent amp for a beginner to build?
Also, Im a bit worried about the lack of proper English instructions - I dont think I'd have to much trouble populating the PCBs and wiring it up, but in the assembly instructions (looks like they used google translator!) theres a section describing what looks like amplifier set up - perhaps setting the bias? The English translation doesnt make any sense! There seems to be more pictures on the Chinese assembly instructions.
HIFIDIYСÐͼ×ÀàA20¹¦·Å×°»ú˵Ã÷(ÕýÔÚ¸üÐÂ, ÓÐÎÊÌâÇë¸úÌù,ÎÒÃÇ»á»ã×Ü) - HIFIDIY ²úÆ·×ÊÁÏרÇø - HIFIDIYÂÛ̳ - Powered by Discuz!
I have some Chinese friends who could, perhaps, help me with the Chinese, although they know nothing about electronics.
The other thing I was wondering, I believe the trans is set for either 115 or 230 V operation - this would suit me as Id need it in 115 V for Japan and 230 for when I move back to UK - would it be just a case of rewiring a couple of leads on the transformer to make the change?
Thanks.
It's a downsized Krell KSA50.
MJL3102/3281 outputs, MJE15030/31 drivers, 2SD669 Vbe device, MPSA+MJE Vas devices, A970/C2240 input transistors (some even use MPSA42/92)
Yes, it is a chass A amplifier, the specification is like this :
Frequency response(HZ) ：5-100K
Output power (watts) : 25(Class A)/100 (Class AB)
Total harmonic distortion: 0.01%
Size( W*H*D) (CM): 25*13*32
The Net weight (Kg) : 13kg
more information can check on http://mall.hifidiy.net
Frequency response(HZ) ：5-100K
Output power (watts) : 25(Class A)/100 (Class AB)
Total harmonic distortion: 0.01%
Size( W*H*D) (CM): 25*13*32
The Net weight (Kg) : 13kg
more information can check on http://mall.hifidiy.net
Recommend This Vendor and Products
For what it is worth, I have built several of their kits, including a cd transport and TDA1541A dac. The boards and parts are all of top quality and the caswork is very nice as well. A little time is necessary to figure out the instructions, but this has become much easier than several years ago when I built the cd transport kit, which was fun to build and works very well to this day. There is a lot of value for money here so you need not hesitate on account of any concerns like that. I trust that you would not be disappointed if you decide to pull the trigger.
For what it is worth, I have built several of their kits, including a cd transport and TDA1541A dac. The boards and parts are all of top quality and the caswork is very nice as well. A little time is necessary to figure out the instructions, but this has become much easier than several years ago when I built the cd transport kit, which was fun to build and works very well to this day. There is a lot of value for money here so you need not hesitate on account of any concerns like that. I trust that you would not be disappointed if you decide to pull the trigger.
Last edited:
yup - I know KSA
but - I was interested in that decreased thingy ....... to see how they decrease it
Sure that they first reduce the PS voltage, then adapt
the current sources while regulating the voltage stages
supplies to reduce increased ripples due to quiescent current
inherent to class A biaising..
going that route - I can draw one of my own .......
I was just curious in one easy piece , looking at printed schmtc , while drinking coffee ...
Perhaps that it s a copy from something published in this site..
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.