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-   -   ★★ Free PCB for JLH 2005 Class-A Amplifier (http://www.diyaudio.com/forums/siliconray-online-electronics-store/200659-free-pcb-jlh-2005-class-amplifier.html)

siliconray 17th November 2011 09:34 AM

★★ Free PCB for JLH 2005 Class-A Amplifier
 
We are offering free PCB for JLH 2005 class-A amplifier
Please get it here:
Free JLH-2005 Class-A Amplifier PCB

Each order is limited to 2pcs.

If you don't have the components please go with this cheap kit:
JLH-2005 Class-A Amplifier Kit for only $24

osscar 17th November 2011 10:17 AM

Two boards ordered - I have always wanted to try JLH. tnx

siliconray 17th November 2011 11:57 AM

Hi Oscar
Thanks for ordered. I saw 5 orders in the past hour.
Are you from Latvia? I'm not sure wether the flat rate shipping service is available for your country. I will ask the courier about it tomorrow.

osscar 17th November 2011 11:58 AM

ok, thnaks. Yes im from LV.

siliconray 19th November 2011 10:53 PM

First bath was sold out. The second batch will be made after the first design is tested. Keep on offering free PCB!

siliconray 21st November 2011 04:27 AM

Fab out!
 
1 Attachment(s)
Begin to ship today, first 25 orders will be shipped soon. Later orders will be shipped a few days later.

siliconray 23rd November 2011 09:29 AM

Happy with the testing reslut!
 
2 Attachment(s)
Today I'm sooooo happy with the testing result. After the following modifications of the original first design I posted:
1. VR1 changed to 100R
2. R13 changed to 10R
3. Q3 changed to BD139

The amplifier is working great! At the beginning the THD is 1% @1KHz/1W/8Ohm, pretty high for a class-A. I realize that Q1 and Q2 should be paired matched. Then I changed them with 2 pair matched transistors, the THD drops to 0.05%!

I also tried with some other transistors such as 2N3055, 2N3773 and finally 2SC5200. In my own opinion I like the sound of 2SC3280 most, high freq is very clear.

BD139 and BD140 works great in the testing. I think it's no need to worry about the high current. The don't have a heatsink and were slightly warm during working.

Hope your guys can also build a great amplifier when you receive my free PCBs.

siliconray 24th November 2011 09:20 AM

Bug and testing report
 
4 Attachment(s)
Sorry for forgetting to mention a bug on the board. A trace is missing on the fist version, the 2 collectors of Q3 and Q8 are not connected. A flying wire can solve this easily

Tested THD with different transistors, testing condition is 1KHz, 6Ohm speaker, 1W output power
2N3055: 0.06%
MJ15003: 0.03%
2SC3280: 0.03%

MJ15003 and 2SC3280 should be better options for Q1 and Q2

kp93300 24th November 2011 10:41 PM

Hi Siliconray,
I am interested to get a kit
You need to buy 2 boards for a stereo set ?
When will your sell new batch of pcb ?
thanks

kp93300

zeonrider 24th November 2011 10:44 PM

I am interested for 2 PCB!

Regards zeoN_Rider


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