"Yuanjing" Gainclone 3886 - eBay amazing value ?

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gainphile

gainphile

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Joined 2007
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The plan is to power my 10-drivers OB using multi-channel gainclone. Was ready to build the usual point-to-point 3875 until I spotted this on EBay.


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


Price is amazing, which comes to about A$12/channel (!). Very tidy. What I am not sure though is the additional op-amp which I believe can be easily bypassed. The other thing, I haven't heard 3888 compared to 3875. I have lived with my 3875 and never had the need to tweak or lust any other amp since day-1.

Any advise?
 
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postpunk

Member
Joined 2004
I've got one of those. It produces a terrible hissing noise, and it hums. I think that the Wimas are all fake, they look like they've been sanded. The chips looks strange too, thinner leggs than normal and the packages are not equaly thick. They too look like they've been sanded off... I would not recommend that crap to anyone.
 
gainphile

gainphile

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Joined 2007
gainphile.blogspot.com
The link is here:

http://cgi.ebay.com.au/ws/eBayISAPI.dll?ViewItem&ssPageName=STRK:MEWAX:IT&item=330324271515

Thanks for the warning. As nuuk said I may just try one.

Hiss would most likely due to the op-amp, this can be bypassed. Hum is more serious and difficult to fix as this is due to trace/grounding design.

I'm not sure what you meant by "sanded". Do you mean they try to sand off the "LM3886" marking ? Any possibility to post a close-up pic?

THanks.
 
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postpunk

Member
Joined 2004
The pics didn't turn out well, too blurry. You can't see anything. But the chips look like they didn't break out clean from the mold. Jagged edges. I have never seen such rough finished casings on any original lm3886. They just have to be fakes.

Edit: Here one can at least see the strange looking corner of one chip..
An externally hosted image should be here but it was not working when we last tested it.

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

Member
Joined 2006
I recently bought a 2 x TDA7293 kit on e-bay for $23 , I haven"t but it together yet but the PCB quality is pretty good , the TDA7293 chips look a bit schetchy , don"t have the same type of printing on them but I"ll see how it turns out...

The PSU PCB looks good and was only $5 with most of the parts...


Cheers
 
M

MadHattter

Member
Joined 2009
So, if all the other components (and PCB) appear to be O.K., buy the amp and replace the supplied chip with your own chip and see if it improved the sound. I don't think it would take much to de-solder the old chip then solder a new chip in. $12.00 for a board and components doesn't seem to be a bad deal.
 
kgc-jr

kgc-jr

Member
Joined 2009
I recently purchased a YuanJing LM1875/NE5532 amplifier kit/board (fully assembled) for $15 (included shipping) on Ebay, and the board construction and components look to me to be of good quality.

The kit does not come with a heatsink for the two LM1875's, but it does have the DC power supply built into the board (FW bridge & 4x4700uF elec.). It also came with the mica insulators and nylon spacers for the LM1875's. All I need is a suitable 18VCT transformer, heatsink, volume control, connectors/jacks, and chassis to build a complete ~25W/ch stereo power amp. Once I have assembled the amp project, I'll post pics and my listening results.

The specs & pics from the auction listing are as follows:

.. uses fiberglass PCB, excellent electrolytic and film capacitors, and precision metal film resistors.

Description:

30W+30W
AC voltage 18V-0-18V
Size 10.4CM X 7.3CM

Package contents:

2 X LM1875+NE5532 Audio Amplifier Board (does not include the aluminum heastsink)

0408_1.JPG

08ae_1.JPG

0adc_1.JPG



The only problem I have with this kit is that there aren't any schematics or documentation (just the board and the auction information). I'm guessing that a 18VCT @ 6A - 7A (100-120VA) Hammond toroid power xfrmer ought to do the trick. If anyone out there has a recommendation for a less expensive transformer source, or can wind one of these for me, I'd like to know.

Additionally, can anyone direct me to the best place to find the heatsink. I'm also not quite sure what size heatsink I should get.


Kgc-Jr
 
leadbelly

leadbelly

Member
Joined 2002
kgc-jr said:
I'm guessing that a 18VCT @ 6A - 7A (100-120VA) Hammond toroid power xfrmer ought to do the trick. If anyone out there has a recommendation for a less expensive transformer source, or can wind one of these for me, I'd like to know.
Click to expand...

No, 18 - 0 - 18 is not 18VCT, it is referred to as 36VCT.

There must be thousands of posts on cheap sources for gainclone transformers on this forum; please search.
 
M

Minion

Member
Joined 2006
Well I assembled my 2 x TDA7293 kit from this guy and it totally fried , Kept blowing fuses so upped the fuse size untill it finally went up in smoke , Both chips fried in the same spot on the plastic and all the elctro"s exploded ..... after words I checked the continuity on the PCB with my DMM and there were a bunch of problems with the through holes not makeing contact with the traces and some shorting on others , I also believe the caps were relabled .... I complained to the seller but he refused to get back to me .....

total crap !!!


The PSU PCB worked fine though ....
 
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aditaquil

Member
Joined 2004
Hi guys, the kits from china always cheap, because they use caps, trans even ICs used from junk yard. That make kits cheap. Sometimes they change original mark on caps, trans or ICs with other mark. When you push voltage to standard, they blowup, because its fake.
Be careful to buy kits from china, they resend junk to your home.
Cheer.
 
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