Sorry, meant to post this with my last response. Then got distracted.
https://www.firstwatt.com/pdf/art_diy_nutube_preamp.pdf
Will do! What/where would you suggest to start? Any suggestions and guidance would be greatly appreciated. I’m still learning 😊
I will have to see what it sounds like maxed out later. I’ve heard/read that volume pots tend to “sound best” at the 2 o’clock range?
There is a thread somewhere from early 2023 where I guided step by step using Behringer UCA-202 and RMAA to take measurments - I would really not restart this again.
But in brief - get yourself an external soundcard (UCA-202, Scarlett Focusrite or something similar) and download REW or RMAA.
I usually use RMAA for its simplicity, REW learning curve is a bit steeper but it provides more capabilities.
Whatever you do, bear in mind that the soundcard input is usually on 2V level so when measuring from speaker terminals (that is the case with power amplifiers or speaker cable ends) you have to use attenuator.
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Sounds best to whom? Joke aside, with 100% vol setting sound should not change at all. And if it does there may be some issue with your wiring.
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Hi Bucks, can you explain what you are referring to by “some issue with your wiring” and how that may be an issue? Admittedly I’m not anywhere experienced as others on this site, but to me if the volume increases as the pot is turned clockwise then the wiring is correct. Please help me understand your question and reasoning. Thanks!
Ok, I just got home and one observation I’ve made is that the volume seems to increase faster (get louder sooner) as I turn the potentiometer clockwise compared to my original 50k pots. Is that a possible issue, meaning the pot is wired incorrectly?
Feed the amplifier with 400Hz or 1kHz signal at input and measure the AC on output in volume knob step by step positions with a DMM.
That will give you the actual "taper" of your volume pot.
Or unsolder the wires from pot and take up the actual taper of it by measuring resistance (this way you can compare it to the old pot).
everything is written on pcb you posted link to, in first post
it's impossible to wire it in wrong way
it's impossible to wire it in wrong way
I got one of those a while ago, from China...
But I never used it, because I convinced myself pretty quickly that the "Alps" pot is a fake - there are a lot of fake Alps pots coming from China. Yours might be genuine, but I'd be wary of it.
I admit issues of wiring was a bit unprecise. In this case I meant the hole circuit, i.e. possible mismatch of driving and receiving impedance, input parallel caps etc.
Ok, silly question time… I haven’t opened up the unit yet because I don’t have time this evening. If I inadvertently reversed the ground and input wires would that cause possible attenuation problems? I’m thinking that the pot would just work in reverse though? Please don’t laugh 😂 , I’m still trying to learn about divider circuits and everything else that makes these circuits work along the way.
Reverting poti terminals not only reverts direction, but in case of a logarithmic taper gives a quite ugly response to rotation angle.
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Altough an older thread, but it's interesting: this is my experience too. I have the same rc volume control unit in my new amp and I always thought there was something wrong. Based on your posting, I ordered real Alps motorized potentiometers yesterday, and I'll just run it with the old controller after I remove the old potentiometer. Have you replaced the potentiometer?
I have had cold solder which happens often at the location of the potentiometer for some reason. Some sound comes out, but something is off. Also when installing the board in the chassis, I had some bad connection occur. I just went over every connection with some extra solder and heat and it worked again.
Removing the old potentiometer and putting in a new Alps motorized unit was and is my intention but I’ve been too busy to get around to it. Although my soldering skills are fairly good, my desoldering skills on an pcb with multiple pads such as with the potentiometer are a little lacking and need practice. In the meantime I’ve replaced the whole unit with a new RK27 Alps stereo pot I had ordered long ago to replace the cheap Dact potentiometer and mounted it on one of the DiyStore boards. The previous sound is back, and dare I say more refined than the Dact unit, and the treble is no longer attenuated. I guess the other plus is a little exercise to go back and forth to change the volume 😂.
Use soldering wick to remove solder and the pins will become loose in their holes (at least with older gear with bigger holes, not necessarily so easy with newest ones still using THT).
Just be careful with pins that have been bent to the board (to hold the element in place) - with these you have to heat with a soldering iron and straighten the pins with a sharper screwdriver at the same time. If the solder has not melted then you risk detaching the solder pad or track end from the board.