71-CCF02-J-5.1
Is there another resistor I can use instead of this one? All the ones online are backordered
Is there another resistor I can use instead of this one? All the ones online are backordered
Give the instructions linked below a shot, let us know what you come up with. The "search similar" and "show similar" buttons are very useful.
https://www.diyaudio.com/forums/pas...-diy-headphone-amp-guide-301.html#post6368530
https://www.diyaudio.com/forums/pas...-diy-headphone-amp-guide-301.html#post6368530
I just ran the 'show similar' and it gave me 18000 matches. It doesn't narrow down the resistance or power rating so just match the appropriate values (in this case 5.1ohms and 2W power rating) and you get 2 matches back. Personally I would go for the Panasonic but Vishay are nice too.
https://www.mouser.ca/ProductDetail/Panasonic/ERX-2SJ5R1/?qs=gQQ/pDEpiRJoziD7fhTQGA==
https://www.mouser.ca/ProductDetail/Panasonic/ERX-2SJ5R1/?qs=gQQ/pDEpiRJoziD7fhTQGA==
I apologize, I totally forgot that you sent me this. I will remember to use this feature from now on!
Thank you Twitchie that's very helpful!
I finally got to sanding the parts of the chassis. I verified, that each individual part has a connection to gnd, but it did not alter the noise floor I described before.
With my K601s I cannot hear any noise, but with my old Apple buds a hiss is present and with my Meze Audios in addition to a very noticable hiss I can still observe a faint humming.
In the attached pictures you can see the ground lift, that twitchie described.
With my K601s I cannot hear any noise, but with my old Apple buds a hiss is present and with my Meze Audios in addition to a very noticable hiss I can still observe a faint humming.
In the attached pictures you can see the ground lift, that twitchie described.
Attachments
If you hear any difference or change in the hiss when you touch the pot it's because the body of the pot needs to be connected to chassis/earth. You could also test this with a probe wire to connect the fastening nut - which you have on the inside of the faceplate but others are using this to connect the pot body to chassis - this is the contact which you can use to ground the pot to earth.
If it's unrelated to the pot grounding then there might be something wrong elsewhere. Do you have any pictures of the entire amp?
If it's unrelated to the pot grounding then there might be something wrong elsewhere. Do you have any pictures of the entire amp?
I just noticed your headphone jack has a metal body - is the part touching the faceplate also connected to ground wire connection coming in? You could be poluting audio ground/output ground if it's actually grounded at the headphone jack to the chassis.
I could not recognize any difference when touching the pot, so i would think the problem is unrelated to it.
Regarding to your idea with the headphone jack: this is something I was asking myself. Having contact to the chassis and therefore to its ground I would pollute my audio ground, wouldn't I? Unfortunately it makes no audible difference when letting the headphone "dangle" off the chassis' side with no connection to its ground. Please let me know, if you need any close up pictures.
Regarding to your idea with the headphone jack: this is something I was asking myself. Having contact to the chassis and therefore to its ground I would pollute my audio ground, wouldn't I? Unfortunately it makes no audible difference when letting the headphone "dangle" off the chassis' side with no connection to its ground. Please let me know, if you need any close up pictures.
Attachments
SelektaM - you need to attach the pot correctly to the front panel, it has no grounding / continuity to the case. In both your pics above you have forgotten this.
Tighten the pot shaft to the front panel with nut and washer then check continuity between pot and back panel.
Tighten the pot shaft to the front panel with nut and washer then check continuity between pot and back panel.
I fired up my whammy board the first time today, and no smoke 🙂 rails measure 16,95V and -16,98V with orange leds. Nice and close together, it looks like it paid off to source 2% tolerance 7915 and 7815 regulator parts (L7815ACV and L7915ACV by ST Micro).
I want to verify one thing though: Is it correct to measure bias current over R16, R22, etc? When I do that I get 94mA, while using 10R resistors (10,8 ohms measured in-circuit). That seems too high? I was expecting 60mA, give or take. Not that anything gets more than hand warm (I am using an 18V transformer)
I want to verify one thing though: Is it correct to measure bias current over R16, R22, etc? When I do that I get 94mA, while using 10R resistors (10,8 ohms measured in-circuit). That seems too high? I was expecting 60mA, give or take. Not that anything gets more than hand warm (I am using an 18V transformer)
Last edited:
High bias could be caused by the optocoupler. Both channels the same? I have seen variation in brands although that is a bit much. The circuit will handle it.
Thanks Wayne.
Both channels measure within 1mA of each other. I'm using Vishay 4N35's.
I did measure again this morning and it's now showing between 87and 89mA. It also might be that my DMM is not showing the correct figures maybe, it's a quite old and crappy one (Vichy VC99 from Aliexpress, bought 10 year ago I think). I only very occasionally measure currents, so it might just be bad at that? A good excuse to get that Brymen I have been eying for a while now 🙂
I would say that at roughly 90mA the heatsinks would be quite warm? In my case they are not warmer than maybe 40 degrees C. Does that sound like a reasonable temp?
Both channels measure within 1mA of each other. I'm using Vishay 4N35's.
I did measure again this morning and it's now showing between 87and 89mA. It also might be that my DMM is not showing the correct figures maybe, it's a quite old and crappy one (Vichy VC99 from Aliexpress, bought 10 year ago I think). I only very occasionally measure currents, so it might just be bad at that? A good excuse to get that Brymen I have been eying for a while now 🙂
I would say that at roughly 90mA the heatsinks would be quite warm? In my case they are not warmer than maybe 40 degrees C. Does that sound like a reasonable temp?
Last edited:
you didn't measure voltage across 10R source resistors, to get Iq?
no need to conduct classic current measurement with meter in-line
no need to conduct classic current measurement with meter in-line
Indeed I just measured mA's. I now measured mV, and there are about 571 of them 🙂 So how does that translate to mA? Although I am pretty handy with a soldering iron, that does not mean that I know what I'm doing 🙂 Can you briefly explain? I vaguely remember it's to do with Ohms law, but I'd love a short lecture 🙂
Last edited:
Perfect, thanks!
It seems I'm all good to go then, I'll just have to be patient until the housing arrives so I can hook everything up.
It seems I'm all good to go then, I'll just have to be patient until the housing arrives so I can hook everything up.
Last edited: