Micros have a serial port and could communicate via RS232 protocol and simple voltage shifting hardware, a development board would have an emulator and USB interface. Maybe someone here has written an infrared interface that could contribute the source code for your project. Maybe even an RF interface running on 433 MHz like car alarms does. All these things are possible, in my experience you want as few remote controls as possible lying around your house.
i think with the help of some arduino library IR remote is fairly easy to implement, which im already planning in
i guess if the only alternative is writing a corresponding program for the PC/smartphone to directly communicate with the MCU i will rather discard this idea, atleast for now, the raspberry pico has a usb interface, so in terms of pc connection its only a software thing i might try later to resolve
Why is everything so unnecessarily complicated when we are already much more advanced technologically these days?
GLA-RCA Volume Control Module 20KOhm with Encoder / Display / Remote control
GLA-XLR Balanced Volume Control Module with Encoder / Display / Remote Control
GLA-RCA Volume Control Module 20KOhm with Encoder / Display / Remote control
GLA-XLR Balanced Volume Control Module with Encoder / Display / Remote Control
its for me not about the cheapest solution, but the most audible transparent..... else i would just use the digital volume control on my dac...
imo fun side aspect: i can do something useful with my arduino knowledge 😀, so its on the other hand really to have something to tinker...
i did some research and preferably you want over a 1:10 ratio of input/output impedance, many output devices like dacs will probably offer 200 ohms or less
where for example my active speakers have 10k input impedance, which is fairly common i think
So in theory with this 10k input impedance version above, one would have 2,5k impedance at 64 db attenuation, somewhere around 1,25k at 32db, everything under 64db i just consider for a "good" mute option
So i think a purely passive version like this probably works out fine? since i still was arguing with myself about a output buffer
I am of the school Volume control first, preamp/output buffer of low impedance at the end to drive long interconnect cables. Some disagree but that's politics. 🙂
the thing im wondering is, how a passive volume control + opamp buffer sound like compared to a classical opamp preamplifier with gain? if this will give a "similar result" the question if i stay completely passive or switch over to an semi-active circuit
i also saw diamond transistor buffers which im curious how they sound compared to opamps, imo discrete solution like the burson v6 vivid dont sound that bad, but they have there own "oldschool-ish" sound signature i would say
the question is do i wanna color the sound with opamps or cables i feel like.... (tho the 1,25k impedance at -32db with the 10k input impedance version i posted above should work just fine with my 10k impedance speakers)
If you have good ears, everything colors the sound. Its unavoidable. All you can do aim for is minimal damage. IME usually a little feedback can be a good thing. More feedback than that can look good on an FFT but not necessarily sound more like real music (in one way or another). Then again, sometimes an amp with a lot of feedback can be quite good. Just not always.
yea i agree, the 1 million dollar question is what is the best compromise 😀
maybe i should just add both options switchable .... i actually like the idea, since you can flavour the sound with different opamps, but two "audiophile" power supplys complicate the whole thing immensively imo
allternatively i could make the input impedance only 5k , which ends up being 1,25k at -64db, 625 ohm at -32db , i think "too low input impedance" is only important for tube gear right?
imo 625 ohm at -32db isnt that worse than a buffer considering its only a passive volume control where you probably can keep volume quite high (adjust volume on your amps etc...)
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Its possible to build simple FET buffers that measure pretty well. IME, they all have a sound though.
Regarding power supplies, seems like a lot of the time they can have a pretty substantial impact on sound. Something we decide to live with or not.
Maybe some tests of quick switching of source impedance into you existing preamp would show what to expect from it?
Regarding power supplies, seems like a lot of the time they can have a pretty substantial impact on sound. Something we decide to live with or not.
Maybe some tests of quick switching of source impedance into you existing preamp would show what to expect from it?
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I have to admit that I've not read all of this long thread, but I can give some opinion and some direct experience.
I don't like on-chip volume control for the bestest audio because, well, long-winded to attempt an objective case.
I worked in amateur radio repair for 15 years. Short-wave transceivers witch usually use banks of relays for directing signals of >100 Watts and also microvolt level. Sometimes the same relays do both jobs (less problematic). They are an absolute pain in the neck. There's one particular otherwise top-notch radio model (FT-102) now quite old, where I believe not a single example remains where the relays have not failed.
Switching high power is usually unproblematic but it's the low level stuff where the relays cause mucho trouble. The contacts go high-resistance (straight failure) intermittent resistance (straight failure if it happens too often) slightly high resistannce (failure either noticeable or only measureable at trade-in time.)
About 20 years ago I built an RF controlled A/B stereo line-level signal switch using a relay, into a motor-driven 10k Alps potentiometer unit for volume. Occasionally I noticed an audio balance problem but it was rare and I put it down to 'one of those things'. A year or two later one channel would disappear. Cycling the relay a few times brought the sound 'back'. Failure can be either noticeable or not. Especially if it creeps up on you slowly. The path which failed is through the normally open relay contacts. I can't be bothered to change the relay yet.
Radio designers were made aware of this problem. Some responded by passing a small DC bias current through the relay path using chokes and capacitors either side to not affect the radio frequency antenna signals passing through. This steady current and the relay's action of actually switching it helped but not completely.
Designs currently on the market have a menu optionwhere a "relay clean" can be initiated which noisily goes through all the relays (and therefore the less or almost never used ones) cycling them a few times.
Where you have a good few volts being switched the distance of the separation of the contacts - caused by stuff which has come to be there but you wish wasn't - can be enough for an arc to be formed which can 'clear the path' and arc through the tiny fractions of a thou (UK thou=001") of stuff that shouldn't be there.
I have an old Marconi comms test set. Much test gear is old because it just does its job. It has a keyboard. Most keys slowly arrived at a point of unuseability. The switches are hard to get at, expensive and rare. I isolated the electronics and got them to swich first 10 Volts through just a resistor, which got them working except where I had to crank up to 30 Volts and many presses. Then all worked first push. Sadly the keys are a bit problematic again but not as bad yet.
Over time the real world's atmostpere plus other factors attack switching contacts made from the finest materials. It just happens. "wiping" contacts where the action of switching involves relative lateral movement of the contacts helps. Hope you are still awake.
I don't like on-chip volume control for the bestest audio because, well, long-winded to attempt an objective case.
I worked in amateur radio repair for 15 years. Short-wave transceivers witch usually use banks of relays for directing signals of >100 Watts and also microvolt level. Sometimes the same relays do both jobs (less problematic). They are an absolute pain in the neck. There's one particular otherwise top-notch radio model (FT-102) now quite old, where I believe not a single example remains where the relays have not failed.
Switching high power is usually unproblematic but it's the low level stuff where the relays cause mucho trouble. The contacts go high-resistance (straight failure) intermittent resistance (straight failure if it happens too often) slightly high resistannce (failure either noticeable or only measureable at trade-in time.)
About 20 years ago I built an RF controlled A/B stereo line-level signal switch using a relay, into a motor-driven 10k Alps potentiometer unit for volume. Occasionally I noticed an audio balance problem but it was rare and I put it down to 'one of those things'. A year or two later one channel would disappear. Cycling the relay a few times brought the sound 'back'. Failure can be either noticeable or not. Especially if it creeps up on you slowly. The path which failed is through the normally open relay contacts. I can't be bothered to change the relay yet.
Radio designers were made aware of this problem. Some responded by passing a small DC bias current through the relay path using chokes and capacitors either side to not affect the radio frequency antenna signals passing through. This steady current and the relay's action of actually switching it helped but not completely.
Designs currently on the market have a menu optionwhere a "relay clean" can be initiated which noisily goes through all the relays (and therefore the less or almost never used ones) cycling them a few times.
Where you have a good few volts being switched the distance of the separation of the contacts - caused by stuff which has come to be there but you wish wasn't - can be enough for an arc to be formed which can 'clear the path' and arc through the tiny fractions of a thou (UK thou=001") of stuff that shouldn't be there.
I have an old Marconi comms test set. Much test gear is old because it just does its job. It has a keyboard. Most keys slowly arrived at a point of unuseability. The switches are hard to get at, expensive and rare. I isolated the electronics and got them to swich first 10 Volts through just a resistor, which got them working except where I had to crank up to 30 Volts and many presses. Then all worked first push. Sadly the keys are a bit problematic again but not as bad yet.
Over time the real world's atmostpere plus other factors attack switching contacts made from the finest materials. It just happens. "wiping" contacts where the action of switching involves relative lateral movement of the contacts helps. Hope you are still awake.
High quality, gold contact relays are necessary. It is recommended by some relay manufacturers to use magnetically latching relays to avoid long-term internal outgassing from constantly energized coil heat. Also relays typically have a minimum current rating, which is the current needed to put the contacts into a low impedance state. Once that level of current flows once, it doesn't need to be repeated again until the contacts are opened and closed again.
is there a way of doing this between my dac and active speakers? im connected over XLR and using the volume pot of the dac
it might be not a bad idea to listen for a change myself
tho i really suspect a 5k input impedance version would be fine, with 5k input impedance im just not sure if you can use all sources, but im not a vinyl/tube guy persay
yea, i have choosen the kemet ec2 because they are silver alloy+gold plating, fairly certain this will sound fine contact wise
i was in the opinion so far that balanced signal are so low current that no arcing is happening inside relay, so no "real" degredation, specially with non-reacting gold plating, maybe im wrong
Probably could be done. Depends on how things are interconnected now. Also, might be enough to check with only one speaker. Question is do you hear a difference, and if so, is it objectionable?
The arcing I refered to is low volts microscopic arcing through the microscopic contamination of contact surfaces - it's beneficial to a degree.
i mean, did some of you test this and heared something beside the potential "rolloff" that is happening between impedance and cable capacitance? atleast roll off wise im probably clear here with a 5k input impedance version having in RL probably max. 1k impedance vs my 10k impedance speakers
Its probably just going to be roll off. Question is do you notice it and if so do you care. Thing is, roll off is not a sharp corner; with only one pole is a gradual thing that can to some extent affect volume level and phase lower than the corner frequency. Also, it may depend on what kind of capacitor your interconnect cable makes (if you have one). Does it produce nonlinear distortion like mylar can do? Is it more clean like polypropylene? I ask because some people hear such effects under some conditions. If you check first, then you know. That's all I'm saying.
hmm i was thinking about this the past 2 days.... im currently playing with an allpass to correct my tweeter response (two way design where tweeter is flipped) (crossover at 2khz, allpass at 8khz), imo this makes a difference, not the phase delay per say, but the deviation from absolute phase
imagining a 30khz roll off i guess the phase delay would be already some degrees off at 15khz
So i actually think i will end up building a design like schitt freya, where you can switch between passive and buffer output and just check what sounds better...
im just not sure yet how/where to implement this
for starters, would this be already a sufficient buffer circuit?
Parallel to C1 and C2, imagine a additional 47uF-100uF cap, just havent added it yet
should i just decouple both power supplys towards ground or also to eachother with 2 additional caps? i think i read so far just towards ground is more desireable, but my own opamp swapping showed hooking up a 47uF cap (+ 0,1uF MKP cap) between V- and V+ was quite beneficial, what do you think?
im unsure what the last dac had as a circuit, but i imagine it was decoupled towards ground and i was decoupling the power supplys additionally to eachother
10-100ohm output resistors were recommended by chatGPT, also the 1k input ohm resistor, which limits current to 15mA at 15V
probably using something like +12/-12V allows for more opamp choices
You'll probably want 100 nF for the local bypassing. I'd use X7R ceramic rated for at least 50 V. They'll have lower ESR and higher SRF than the Wimas.
You'll want 10-47 uF on each rail where the power enters the circuit board. I'd use a plain electrolytic cap for this. There's no reason to go overboard here. More is not always better.
I'm curious about the purpose of the 1 kΩ in series with the input. If you're going for ESD protection, I suggest a pair of diodes to V+ and V- instead. If not, you can go without the 1 kΩ.
The 10 Ω can be handy for driving longer cables. Some put it inside the feedback loop.
Tom
You'll want 10-47 uF on each rail where the power enters the circuit board. I'd use a plain electrolytic cap for this. There's no reason to go overboard here. More is not always better.
I'm curious about the purpose of the 1 kΩ in series with the input. If you're going for ESD protection, I suggest a pair of diodes to V+ and V- instead. If not, you can go without the 1 kΩ.
The 10 Ω can be handy for driving longer cables. Some put it inside the feedback loop.
Tom