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Discussion Starter #41
Ok great. I'll start simple. I will build a complete controller A to Z and test it with my AV receiver. I don't have a lot of noisy equipment, but I'll do my best to induce some. I'll take some measurements too. Do you think grounding the pot chassis, as did the guy in the video, is necessary? My pots have plastic bodies and metal knobs.
 

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Discussion Starter #45
Got what I could finished with the prototype controller. I'll use this one as the bass knob. Had to de-solder the cheap pots that came with the boards (long story, I asked the ebay seller to ship boards only and I got boards with pots and plugs instead) and solder on my boards. Continuity on both right and left channels and 1.6ohm with volume max and 48.6ohms volume min. As soon as I can find the 50' of Canare L-4E6S cable I bought I'll get the RCA connectors on and tie everything together. I have a question about the braided shielding but I'll draw up a quick schematic for a separate post.

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Discussion Starter #46
Solder on my pots, is what I meant to say in the above. I can't figure out how to edit posts on this forum.
 

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Are those ohms or kohms?
If it is ohms, then it seems like it might be too low?

Was it measured between the output and the ground?
Or the input and the output?
 

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Discussion Starter #48
Ohm for vol max and kohm for vol min, sorry about that! I measured input to output on both channels. Is it normal for there to be a slight differential between the channels or did I fry the pot while soldering it?

Left channel vol min: 46.5 kohm
Left channel vol max: 1.6 ohm

Right channel vol min: 48.8 kohm
Right channel vol max: 1.4 ohm
 

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Ohm for vol max and kohm for vol min, sorry about that! I measured input to output on both channels. Is it normal for there to be a slight differential between the channels or did I fry the pot while soldering it?

Left channel vol min: 46.5 kohm
Left channel vol max: 1.6 ohm

Right channel vol min: 48.8 kohm
Right channel vol max: 1.4 ohm
Seem pretty normal...
People can hear a 3dB difference in volume level, do you have an estimate for what the the 46.5 and 48.8 kohms is in terms of volume difference?
If it is less greater than 3dB then redo it, but I think you will find it is probably less than 3 dB.


If you have measurements between the output and the ground that would be better.
I would think that you want a 600 ohm resistor across the input when you do that measurement of the impedence at the output side.

That measurement may be more enlightening.
I am still unsure whether the outer shield was tied into the pot ??
If the pot is inline, then I would expect that it would not be doing as much volume control as you expect it should.

So I await your bench test results.
 

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Discussion Starter #50
I wouldn't have a clue how to convert resistance to dB. Is there a formula?

There is no shield at this point, because there is no cable. I can't find my audio cable. I bought a bunch of orange and black and it's in a box somewhere. I just need to find it. The grey cable with the white connectors you see in the first photo is what is plugged into the board using the connectors. They came with the PCB's. I'm just touching probes to red in and red out and white in and white out (R ch, L ch, respectively) at the loose connector ends. I finally broke the language barrier with the Chinese ebay seller last night and they now understand that I only want bare PCB's, so I ordered 20 of them. Transit time wasn't that bad for the last order at 3 weeks on the dot. This controller is just the prototype. I'll solder direct from the audio cable to the PCB when the bare boards come in. On that note, the shield is the other question I had but have yet to draw the schematic, I'll do that tonight. I need to know if it's best practice to ground the shield at the source side only of each cable and leave it floating on the run (signal direction), or through all of the components, or if I should ground shield on source end of every cable, or both ends, etc. etc.
 

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Discussion Starter #51 (Edited)
Also, I need to split the signal at the HU. Remember, I will only be using RCA Front Out to supply the entire system.

Would these suffice?


Edit: Split the signal out of the first pot, that is.
 

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Discussion Starter #52 (Edited)
Do I tie the shielding to ground at the source end (HU) of the head unit cables only, then leave the shielding floating on all cables after that? This is getting a bit complicated and it's because I don't understand the theory so well. I also understand there are two schools of thought when it comes to shield grounding configurations: Some tie shields to ground on both ends of a cable, the other group shields source end only.

I'll be using SKW interconnects with everything I DON'T need to make a cable for (pot cables).


Edit: The below image has an RCA at the amp end because I forgot that it would be a pot PCB. Should be the same concept though. The below cable would be HU out to PCB in, so on the PCB out, should I tie the shielding to ground and leave it floating at the amplifier input? So glad I figured out how to edit posts!

258890
 

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Do I tie the shielding to ground at the source end (HU) of the head unit cables only, then leave the shielding floating on all cables after that? This is getting a bit complicated and it's because I don't understand the theory so well. I also understand there are two schools of thought when it comes to shield grounding configurations: Some tie shields to ground on both ends of a cable, the other group shields source end only.

I'll be using SKW interconnects with everything I DON'T need to make a cable for (pot cables).


Edit: The below image has an RCA at the amp end because I forgot that it would be a pot PCB. Should be the same concept though. The below cable would be HU out to PCB in, so on the PCB out, should I tie the shielding to ground and leave it floating at the amplifier input? So glad I figured out how to edit posts!

View attachment 258890
I had a course in shielding and grounding about 15-18 years ago by a fellow name fred harris. I'll se if I can find the books that he used and it's author.
I trust this Harris fellow and I think I am not alone.

I recall that it actually was a bit complicated., but it was in agreement with the modern phayis of the last few centuries.
 

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Discussion Starter #54
Sounds good, thank you!. Based on the reading I have done, and my intuition (which is based on exactly zero formal, advanced education in the subject, btw) tells me that tying the shield to ground on the proximal end (relative to the source) of all pot cables makes sense, and will most likely be sufficient for my application.
 

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Are you just wanting to build this yourself? JL Audio makes or made some passive rca volume controls. They're pretty damn good quality, but don't last long as subwoofer volume controls (less than a year).
 

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1) Have you been too busy to test it?

Or...
2) are you at the point yet where you are trying figure out why the volume is the same out of the speakers irregardless of where your controller knob is set?
 

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Discussion Starter #59
1) Have you been too busy to test it?

Or...
2) are you at the point yet where you are trying figure out why the volume is the same out of the speakers irregardless of where your controller knob is set?
Now you're scaring me! Why in the world would you suggest that would be the case???
 
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