Hello ppl, longtime lurker here. I'm not really active in online communities, although I find a lot of useful info on diyaudio forums and keep coming back a lot.
Now I've a question where I would like to find out 1 or more answers to and hopefully have the collective hive mind to inspire me with practical and high quality analog and maybe original solutions.
I'm looking for a way to switch audio line level signals, after a linkwitz riley filter bank, with the least switching noise. My first choice incorporated the 4066 with some logic to debounce and flipflop momentary switches. Then I was thinking of putting in some more logic to incorporate zerocrossing switching with lm339 comparator. Does this work? I made some kicad sketches but I havent breadboarded it yet.
Or maybe do you recommend switching (fast fading?) With jfets?
Looking forward to hear your thoughts.
// Jeroen, Sweden
Now I've a question where I would like to find out 1 or more answers to and hopefully have the collective hive mind to inspire me with practical and high quality analog and maybe original solutions.
I'm looking for a way to switch audio line level signals, after a linkwitz riley filter bank, with the least switching noise. My first choice incorporated the 4066 with some logic to debounce and flipflop momentary switches. Then I was thinking of putting in some more logic to incorporate zerocrossing switching with lm339 comparator. Does this work? I made some kicad sketches but I havent breadboarded it yet.
Or maybe do you recommend switching (fast fading?) With jfets?
Looking forward to hear your thoughts.
// Jeroen, Sweden
Well there are many far better analog switch chips now than the CD4066 !! Sub-ohm on-resistances are available even. Distortion is a big issue with the high resistances of the 4066,
unless you use special circuitry to pass the signal in current mode.
You can route a comparator to the clock of a DQ flip-flop to gate the control signal into an analog switch. However if you are routing the audio through a comparator you need to be very careful that logic signal doesn't couple back into the audio.
unless you use special circuitry to pass the signal in current mode.
You can route a comparator to the clock of a DQ flip-flop to gate the control signal into an analog switch. However if you are routing the audio through a comparator you need to be very careful that logic signal doesn't couple back into the audio.
Yes the 4066 is a poor quality switch. For a bit more money you can get much better On resistance vs Capacitance and control voltage feedthrough
Analog and Maxim dominate this market
Analog and Maxim dominate this market
panorama of circuits with differents technologies :
https://www.sonelec-musique.com/electronique_realisations_commutateur_audio_presentation.htm
TI solutions with TS12A451x in dip package
http://www.ti.com/lit/slyb125
other classical solution with MAX4910/MAX4911/MAX4912
MAX4910 Quad-SPDT Clickless Audio Switches with Negative Signal Handling
https://www.sonelec-musique.com/electronique_realisations_commutateur_audio_presentation.htm
TI solutions with TS12A451x in dip package
http://www.ti.com/lit/slyb125
other classical solution with MAX4910/MAX4911/MAX4912
MAX4910 Quad-SPDT Clickless Audio Switches with Negative Signal Handling
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CMOS gates are fine for PA systems and instrument amps where fair fidelity and artifacts is good enough. CMOS gates need to be clamped to prevent latch-up. There is also enabled op-amps and LTP switching. Audiophiles may only be happy with switches and possibly mechanical relays but it's possible to mess up whatever method you choose. Always keep in mind draining any residual DC and caps. A temporary global mute of about 100mS can clean up pops and clicks. JFETs make good shunts up to a small voltage if you add half the audio to the gate voltage to keep them symmetric, but such circuits usually require gain and noise.
LDR's switch without pop https://www.newark.com/advanced-photonix/nsl-32sr2/optocoupler-resistor-2000v/dp/71C0279
Another https://www.newark.com/advanced-photonix/nsl-32sr3/optocoupler-resistor-2000v/dp/71C0280
They are cheaper in the UK: https://www.newark.com/advanced-photonix/nsl-32/optocoupler-2kv-resistive-o-p/dp/67C8926
newark outside the usa is farnell, operates worldwide.
Another https://www.newark.com/advanced-photonix/nsl-32sr3/optocoupler-resistor-2000v/dp/71C0280
They are cheaper in the UK: https://www.newark.com/advanced-photonix/nsl-32/optocoupler-2kv-resistive-o-p/dp/67C8926
newark outside the usa is farnell, operates worldwide.
Some how DIYA or Edge is destroying your URLs so I'll try to repost them:
https://www.newark.com/advanced-photonix/nsl-32sr2/optocoupler-resistor-2000v/dp/71C0279
'https://www.newark.com/advanced-photonix/nsl-32sr2/optocoupler-resistor-2000v/dp/71C0279'
https://www.newark.com/advanced-photonix/nsl-32sr3/optocoupler-resistor-2000v/dp/71C0280
'https://www.newark.com/advanced-photonix/nsl-32sr3/optocoupler-resistor-2000v/dp/71C0280'
https://www.newark.com/advanced-photonix/nsl-32/optocoupler-2kv-resistive-o-p/dp/67C8926
'https://www.newark.com/advanced-photonix/nsl-32/optocoupler-2kv-resistive-o-p/dp/67C8926'
I know that the "Insert Image" does not work and you have to "Attach" images instead.
PS: No it seems futile so lets try putting the links in a text file?
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BTW, LDRs are great for attenuators but they niether go to zero nor infinity. And they are slow to rise resistance, which is fine for compressors where you would normally integrate a rectified audio anyway. My friends in the scope business use latching relays in the attenuators.
Amazon.com: SMAKN 12V 6-Channel Relay Module High/Low Level Triger Self-Lock Relay: Home Audio & Theater
Latching Low Signal Relays - PCB | Mouser
Amazon.com: SMAKN 12V 6-Channel Relay Module High/Low Level Triger Self-Lock Relay: Home Audio & Theater
Latching Low Signal Relays - PCB | Mouser
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Are LDR's still manufactured today? I think they're obsolete due to cadmium sulfide they consist of?
Best regards!
Best regards!
I made a volume control back in the 80's with CD4066's. Distortion from them is lower then the LF353 op amp that fed them.
They work very well, however there are better chips available now.
The major limitation is the 18v p-p max signal level.
They work very well, however there are better chips available now.
The major limitation is the 18v p-p max signal level.
The advanced photonics NSL-32SR2 and NSL-32SR3 were in stock at newark SC and farnell UK 4/28/20. The more expensive one has 40 ohm on resistance instead of 60 ohm. 1 megohm off after 10 minutes.
63% rise time & decay times are 5 msec, which is why they don't pop. 20 ma on current.
At $3.50 each they are not cheap, but neither are Maxim or AvDev analog switches.
This is exactly what I'm trying to do. The logic is the easy part. The way to switch the signals on and off would be the part where I'm looking for alternatives to the 4066.
Thank you people! Optocouplers are going to be a bit expensive since I need at least 8. Relays are out of the question because they'll give switching noise while music is playing. I'm working on a type of isolator filter bank where I can enable and disable the different signal paths, while the music is playing. Anything solderable by hand? (Like a bit more easy to solder then TDFN packages?)
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Some decent products did use JFETs as audio switches back in the day.
I know there were McIntosh preamps that did - one that I remember is the C35. You could probably download the schematic just to see what they did. If memory serves, I think they used the 2N4392 or PN4392.
The Hafler 915 preamp used the (really old) CD4051 & CD4053 CMOS transmission gates for switching. As already mentioned, you can of course find higher performance parts these days, but that preamp measured well and sounded good.
good luck!
mlloyd1
I know there were McIntosh preamps that did - one that I remember is the C35. You could probably download the schematic just to see what they did. If memory serves, I think they used the 2N4392 or PN4392.
The Hafler 915 preamp used the (really old) CD4051 & CD4053 CMOS transmission gates for switching. As already mentioned, you can of course find higher performance parts these days, but that preamp measured well and sounded good.
good luck!
mlloyd1