Not quite actually 🙂 - truth is I have two of these coming in the post tomorrow... maybe there is some very easy way to improve what must have been a hard BOM saving affair....
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I've read recently here that NE5532 recommended PSU decoupling scheme is to have a cap between V- and V+. This is the scheme you use :
But your opamp is not a 5532 but a LM4562, it is a fast one and may be picky about decoupling. Better to have a 100nF to Gnd on V+ and on V+, both as close as possible to V+ and V- pins.
I'll also remove the 1u or use a 10u. 1u value is too close to 100n and may conduct to unexpected resonances.
But your opamp is not a 5532 but a LM4562, it is a fast one and may be picky about decoupling. Better to have a 100nF to Gnd on V+ and on V+, both as close as possible to V+ and V- pins.
I'll also remove the 1u or use a 10u. 1u value is too close to 100n and may conduct to unexpected resonances.
Those output filter capacitors look like class I ceramic capacitors (C0G) which work just as well as any audiophile-grade film caps.
I have on my table:
https://www.ikea.com/se/sv/p/smahagel-usb-laddare-med-1-port-vit-70538728/
https://www.ikea.com/se/sv/p/varmfront-portabel-batteriladdare-bla-70555647/
Somewhat OT... sorry!
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https://www.ikea.com/se/sv/p/smahagel-usb-laddare-med-1-port-vit-70538728/
https://www.ikea.com/se/sv/p/varmfront-portabel-batteriladdare-bla-70555647/
Somewhat OT... sorry!
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I'm thinking of getting rid of the 74HC14 altogether and using an MCP120 for the PDN circuit. I don't think there's a real need for the MUTE circuit either since I have a relay protection circuit on the speakers.
https://www.microchip.com/en-us/product/mcp120
https://www.microchip.com/en-us/product/mcp120
In the SU-1 there is a component (orange star) at the very last position before the output terminals - is this a turn on/off bump stopper? Is bump a problem? I see you have 10uF decoupling between + and - close to OP amp which SU-1 dont have.
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It does have those caps, they're the ceramics at the top and bottom of the op-amp. Could be a larger value like 10uF, it's possible for that case size.
Don't know what the other IC does, if you get a part number I'd be interested to find out.
From my experience decoupling op-amps is really crucial, but some still have turn on/off noise, so I have a relay system on my amps.
Don't know what the other IC does, if you get a part number I'd be interested to find out.
From my experience decoupling op-amps is really crucial, but some still have turn on/off noise, so I have a relay system on my amps.
I no like. Do one dare to short this one out do you think? Or will there be big bumps on power on or/and off?
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Those analog mute switches aren't good for +-15v. One reason why Topping runs opamp rails at +-11v.
Better to substitute a gold-on-silver contact small signal relay, such as those made by Omron.
Better to substitute a gold-on-silver contact small signal relay, such as those made by Omron.
Probably the same reason Topping and SMSL use analog switch ICs instead of discrete transistors: Better linearity with the ICs.
Switching FETs are commonly used for signal routing in guitar pedals though.
Switching FETs are commonly used for signal routing in guitar pedals though.
Muting can be done in different ways, but with the AK4493, like many (or all?) AKM converters, it will generate spikes at relatively high levels when coming out of reset and when changing the MCLK to change the sample rate. So some kind of muting should definitely be used. The SGM3710 looks like an easy solution (perhaps not for DIY due to the package), with good linearity. But yes, I can imagine that it will be prone to ESD problems unless additional protection is used. The series resistors on the outputs do not help much against high voltage ESD pulses.
Royal snake oil, nothing else.
Anyway, during muting you should not hear anything and then what does the distortions introduced by the muting circuit matter.
And in normal operation, a well-designed circuit must be as if it were not there.
FET transistors are not suitable for this function for reasons of technological achievement, but there are bipolar transistors specially designed for this task. The first time I found them in my old 10-band equalizer, thruhole transistors, but searching on the net I found that there are also modern SMD transistors for this task, and they are neither expensive nor hard to find.
You just have to think like an engineer and not an audiophile.
The SGM3710 is not suitable at all for this task and I don't understand how it was put in that position.