Fix
Post 612 is my amp , (almost) dead quiet , some noise with ear at the speaker , but no hum ! See the separation of input and speaker wires .
Good luck buddy !
Cheers ,
Rens
Look at the pictures in post 180 and 612 for the proper grounding .
Post 612 is my amp , (almost) dead quiet , some noise with ear at the speaker , but no hum ! See the separation of input and speaker wires .
Good luck buddy !
Cheers ,
Rens
For the grounding-problem: Yes. Define ONE point And connect there all analog and digital ground wires as long as they are not interconnected on PCB's or internal wireing. This is also applicable to the "0" wire of the PSU.
Further: I've got the faintest idea how to solve the blue-LED problem
Blue leds
I cut a toslink cable in five pieces and connected them to the blue led's with a piece of 3mm ID tubing . The other side of the 1 mm fiber sticks in to the front panel and that makes a 1 mm blue Led , and that looks pretty cool !
Cheers ,
Rens
For the grounding-problem: Yes. Define ONE point And connect there all analog and digital ground wires as long as they are not interconnected on PCB's or internal wireing. This is also applicable to the "0" wire of the PSU.
Further: I've got the faintest idea how to solve the blue-LED problem
I cut a toslink cable in five pieces and connected them to the blue led's with a piece of 3mm ID tubing . The other side of the 1 mm fiber sticks in to the front panel and that makes a 1 mm blue Led , and that looks pretty cool !
Cheers ,
Rens
Attachments
Ok so i tried to ground the speaker wires and the amp boards to my " star Ground" the damn hum is there still.
Now all the Grounds are in one place except the RCA.
I am starting to belive that the hum is comming from the tube buffrer, as it only gets its ground from rca ground.
The thing is that i have a small transformer 35va that has 2x12v ac out, and i have one 12v for speaker protect and one for tube. This dosent have the Zero volt.
Here are the install instrucitons:
Now all the Grounds are in one place except the RCA.
I am starting to belive that the hum is comming from the tube buffrer, as it only gets its ground from rca ground.
The thing is that i have a small transformer 35va that has 2x12v ac out, and i have one 12v for speaker protect and one for tube. This dosent have the Zero volt.
Here are the install instrucitons:
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Tube buffer
Easy to check ,
Connect the RCA wires directly to your Class D amps , bypassing the tube buffer and see if you have any hum , connect a source and play some music ,if this works ok , draw a complete wiring schematic of your amp including the tube buffer and post it and we troubleshoot further
We will get there!
Cheers ,
Rens
Easy to check ,
Connect the RCA wires directly to your Class D amps , bypassing the tube buffer and see if you have any hum , connect a source and play some music ,if this works ok , draw a complete wiring schematic of your amp including the tube buffer and post it and we troubleshoot further
We will get there
!Cheers ,
Rens
Ground loop
Not good ,
A bit busy today , come back on it tomorrow . You have two groundpoints . ALL grounds should go to one star point .
The fact that it's still humming with your RCA input directly coupled to the L20D's is a good sign , it's not in your tube buffer .
Isolate your star point from the chassis . Take one heavy wire from your PSU ground to the star point and connect all grounds to this point , Speaker ground , Amp ground etc . I'll make a drawing tomorrow or Saturday. Only connect the safety ground to the chassis .Try reversing the polarity of one of your 12V AC connections , either to the speaker protect or the Tube buffer
Cheers ,
Rens
Not good ,
A bit busy today , come back on it tomorrow . You have two groundpoints . ALL grounds should go to one star point .
The fact that it's still humming with your RCA input directly coupled to the L20D's is a good sign , it's not in your tube buffer .
Isolate your star point from the chassis . Take one heavy wire from your PSU ground to the star point and connect all grounds to this point , Speaker ground , Amp ground etc . I'll make a drawing tomorrow or Saturday. Only connect the safety ground to the chassis .Try reversing the polarity of one of your 12V AC connections , either to the speaker protect or the Tube buffer
Cheers ,
Rens
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Which transformer , the 12 V or the 50V one , that's why I suggested reversing one of your 12 volt AC lines . If it is the big one you could have DC voltage on your grid and we can solve that . And you should ground everything to an Isolated star point !
Cheers , Rens
I just found out it's 6.30 in the morning at your place and cold
What the F ?Going for a swim in the pool now with a cold Heineken !
Cheers ,
Rens
Its the bigone Yes. (50v).. I might need to try to isolate the Earth then. Just ground everything together and dont let it touch the chassis. Seems simple.
Yeah its the Middle of the night, and im at work. Outside it is minus 15 degree celsius. FTW Winther......... Oh the irony...
Yeah its the Middle of the night, and im at work. Outside it is minus 15 degree celsius. FTW Winther......... Oh the irony...
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Steel bolt
Is your transformer getting warm ?
From the picture I can see that you use a steel bolt to attach it to the chassis .
Take the bolt out and see if the humming stops . If it does , use a brass bolt .
Off to the pool now
Cheers ,
Rens
Is your transformer getting warm ?
From the picture I can see that you use a steel bolt to attach it to the chassis .
Take the bolt out and see if the humming stops . If it does , use a brass bolt .
Off to the pool now
Cheers ,
Rens
D
Deleted member 148505
Is the hum high frequency or just 60hz? What cable did you use for the input?
I also had a problem on high frequency noise with my L25D when I used a tube buffer on it.
I isolated the possible sources of problem one by one and found out that using shielded cables on input somehow removed the noise.
In the picture you can see that I used ordinary twisted cables, but when I replaced those with shielded cables, the noise was gone.
I also had a problem on high frequency noise with my L25D when I used a tube buffer on it.
I isolated the possible sources of problem one by one and found out that using shielded cables on input somehow removed the noise.
In the picture you can see that I used ordinary twisted cables, but when I replaced those with shielded cables, the noise was gone.
Attachments
Is your transformer getting warm ?
From the picture I can see that you use a steel bolt to attach it to the chassis .
Take the bolt out and see if the humming stops . If it does , use a brass bolt .
Off to the pool now
Cheers ,
Rens
No the tansformer is not getting warm. Im gonna try removing the bolt later today!
The thing is that its a very low humming sound, same noice that comes from the transformer itself. And the thing is that its only present when i dont have any RCA coupled in. When i connect the RCA tha humming goes awaY!
Yeah i use ordinary silver cables with pvc.
I would think that any signal wires inside the case with a class D amp need to be shielded. Unless they are very, very short runs. Shielding and grounding are two separate things. Not all shields are necessarily grounded, but can be.
My L25D (LJM) is one the best sounding amps I've built. I'm using it together with the Doug Self 2012 Pre I built and it really does justice to the music and speakers I use with. Of course, it's waiting to come out of boxes (after a move last year), and after I finish my man-cave in the basement.
Rick
Okey.. another problem has occurd. I tried for the first time to connect it to my onkyo reciver from its preouts, and i there came LOTS of noise! I have on my test bench only used it with my ipad directly connected and then its no noise. WTF????
So the problems are as follow:
- Low transformer hum when no inputs are connected, but totally silent when RCA>jack>Ipad is connected. Works great.
- When onkyo reciver is connected Lots of static and noise.
Gonna try to bypass the tube buffrer when connecting to the onkyo..
So the problems are as follow:
- Low transformer hum when no inputs are connected, but totally silent when RCA>jack>Ipad is connected. Works great.
- When onkyo reciver is connected Lots of static and noise.
Gonna try to bypass the tube buffrer when connecting to the onkyo..