This looks good as well... pure class A, differential input allows for single-ended and balanced sources. Not sure about the (AliExpress) parts quality...
Beautiful...!!
https://vi.aliexpress.com/item/1005...537,tpp_buckets:668#2846#8112#1997&pdp_ext_f=
Even better...
Get the second-hand original amplifier from Japan (eBay), and then replace the power supply (if you are in a non-110V AC country). Place a high-quality 2 x + and - 18V DC regulator board of your choice, and get a suitable transformer. Place the regulator board close to the main PCB capacitor bank... You'll end up owing a great amp for a reasonable amount of money.
Otherwise... aliexpress.... unknown parts quality (replace all semiconductors..?), power supply, transformer, case...
https://www.ebay.com/itm/Audio-Tech...2879?_trksid=p2349526.m4383.l4275.c4#viTabs_0
Beautiful...!!
https://vi.aliexpress.com/item/1005...537,tpp_buckets:668#2846#8112#1997&pdp_ext_f=
Even better...
Get the second-hand original amplifier from Japan (eBay), and then replace the power supply (if you are in a non-110V AC country). Place a high-quality 2 x + and - 18V DC regulator board of your choice, and get a suitable transformer. Place the regulator board close to the main PCB capacitor bank... You'll end up owing a great amp for a reasonable amount of money.
Otherwise... aliexpress.... unknown parts quality (replace all semiconductors..?), power supply, transformer, case...
https://www.ebay.com/itm/Audio-Tech...2879?_trksid=p2349526.m4383.l4275.c4#viTabs_0
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I have audible hum at about 10 hour volume pot.
Is there any efficient way to reduce it? All parts are from Aliexpress (may be low quality).
Currently I don't use a chassis, only volume pot is mounted to a metal. If I touch or connect it to ground earth, there is more hum noise.
I just experimented this diy kit for several hours. Should I wait and burn-in more?
Thinking of improvement but I do not have knowledge of electronic to verify them.
How do you think and any advice/suggestion please?
1) Reduce gain (Change 2 Resistors 680R near opamp to 2,2K).
https://www.head-fi.org/threads/the...e-amp-lehmann-black-cube-linear-clone.501046/
I found this
2) Make snubber for input power and output.
Reference below.
Plan values:
Is there any efficient way to reduce it? All parts are from Aliexpress (may be low quality).
Currently I don't use a chassis, only volume pot is mounted to a metal. If I touch or connect it to ground earth, there is more hum noise.
I just experimented this diy kit for several hours. Should I wait and burn-in more?
Thinking of improvement but I do not have knowledge of electronic to verify them.
How do you think and any advice/suggestion please?
1) Reduce gain (Change 2 Resistors 680R near opamp to 2,2K).
https://www.head-fi.org/threads/the...e-amp-lehmann-black-cube-linear-clone.501046/
I found this
2) Make snubber for input power and output.
Reference below.
Plan values:
- Input: 220nf or 330nf and 10Ohm Resistor in serie.
- Output: .0.022uf cap and 10Ohm Resistor in serie.
Just leave the parts alone at the moment...
Look at the main PCB... there's no mounting hole that is DC coupled to the ground fill. You will need to place that PCB in a metal enclosure and connect the blue dot (below) to that enclosure. Scrape the paint first.
The potentiometer case should be in direct contact with the enclosure as well - scrape the paint to ensure good contact.
Connect the mains power ground lead to the case (scrape the paint).
The RCA connectors should be isolated from the case.
The above should make all the difference.
Few additional steps, only if required:
a) The RCA ground washer (which is isolated from the case) could be connected to the case via a 0.1uF disk ceramic cap. This is done to couple the RF noise to the ground while providing DC isolation. Probably not required...
b) The blue circle ground point on the PCB (see the photo above) could be connected to the case via a 10-ohm resistor....or what was suggested already - via a 10ohm NTC (CL60)... see which option works better for you (option 1: direct connection using a short braided wire; option 2: use a 10ohm wire wound resistor.. or any 10ohm / 2W resistor, or an NTC)
NOTE: unless you want to experiment and learn... dump that thing in a rubbish bin and consider what I suggested above in my previous post - the Audio Technica AT-HA5000 second-hand amplifier. It may actually be cheaper in a long run, AND it will give you a great sound and a beautiful case.
Look at the main PCB... there's no mounting hole that is DC coupled to the ground fill. You will need to place that PCB in a metal enclosure and connect the blue dot (below) to that enclosure. Scrape the paint first.
The potentiometer case should be in direct contact with the enclosure as well - scrape the paint to ensure good contact.
Connect the mains power ground lead to the case (scrape the paint).
The RCA connectors should be isolated from the case.
The above should make all the difference.
Few additional steps, only if required:
a) The RCA ground washer (which is isolated from the case) could be connected to the case via a 0.1uF disk ceramic cap. This is done to couple the RF noise to the ground while providing DC isolation. Probably not required...
b) The blue circle ground point on the PCB (see the photo above) could be connected to the case via a 10-ohm resistor....or what was suggested already - via a 10ohm NTC (CL60)... see which option works better for you (option 1: direct connection using a short braided wire; option 2: use a 10ohm wire wound resistor.. or any 10ohm / 2W resistor, or an NTC)
NOTE: unless you want to experiment and learn... dump that thing in a rubbish bin and consider what I suggested above in my previous post - the Audio Technica AT-HA5000 second-hand amplifier. It may actually be cheaper in a long run, AND it will give you a great sound and a beautiful case.
1. Look at the main PCB... there's no mounting hole that is DC coupled to the ground fill. You will need to place that PCB in a metal enclosure and connect the blue dot (below) to that enclosure. Scrape the paint first.
=> This is very difficult for me. At the red point, no mounting hole.
2. The potentiometer case should be in direct contact with the enclosure as well - scrape the paint to ensure good contact.
=> Ok
3. Connect the mains power ground lead to the case (scrape the paint).
=> Is this center line (0v) of transformer secondary ?
4. The RCA connectors should be isolated from the case.
=> Ok.
The above should make all the difference.
Only one thing I made (mount headphone jack to the enclosure) also reduce hum noise much. volume pot is at 12h, no music, but hum noise very small, less than before.
Thank you.
=> This is very difficult for me. At the red point, no mounting hole.
2. The potentiometer case should be in direct contact with the enclosure as well - scrape the paint to ensure good contact.
=> Ok
3. Connect the mains power ground lead to the case (scrape the paint).
=> Is this center line (0v) of transformer secondary ?
4. The RCA connectors should be isolated from the case.
=> Ok.
The above should make all the difference.
Only one thing I made (mount headphone jack to the enclosure) also reduce hum noise much. volume pot is at 12h, no music, but hum noise very small, less than before.
Thank you.
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