Hi all,
I'm working on a few projects at the moment. This one is an eight channel DAC using the AK4458 with transformer outputs. It may not work well or may sound dreadful but I'm hopeful!
AK4458 8ch DAC
LT3042 regulators
Precision voltage source
Opamp Vref buffer
Cinemag CM-10100 transformers - http://cinemag.biz/output/PDF/CM-10100.pdf
MiniXLR Outputs
8V to 18V input proection circuit.
Fun to learn along the way as to why some things work and something things don't.
At a slightly higher VREF voltage, the swing at 5.25v should be about +/- 3.05v at full scale ~ 3dBu. THD+N should be below -110dB, SNR over 118dB.
Watch this space.
I'm working on a few projects at the moment. This one is an eight channel DAC using the AK4458 with transformer outputs. It may not work well or may sound dreadful but I'm hopeful!
AK4458 8ch DAC
LT3042 regulators
Precision voltage source
Opamp Vref buffer
Cinemag CM-10100 transformers - http://cinemag.biz/output/PDF/CM-10100.pdf
MiniXLR Outputs
8V to 18V input proection circuit.
Fun to learn along the way as to why some things work and something things don't.
At a slightly higher VREF voltage, the swing at 5.25v should be about +/- 3.05v at full scale ~ 3dBu. THD+N should be below -110dB, SNR over 118dB.
Watch this space.
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Yes, I think they specify 1k minimum SE, 2k differential or something around those values. That's OK then, you will see if those resistors are needed at all, I would maybe place just some 27R melfs. Also, tracks going to the transformers and connectors should be as differential as you can get them. Setup Altium to do it for you.
I think it could sound quite good. It all depends on the transformers really.
I think it could sound quite good. It all depends on the transformers really.
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Thanks! Noted.
Currently figuring out the best way to supply Vref and what cap materials and sizes to use.
At the moment I create 5.25 from an LT3042 that supplies Vdd. This trace then supplies a OPA1611 buffer into the Vref net.
You’ll see the 4 large cans around the AKM. Initially 6SVPC820M, with 0.22uF ish ceramic or FCA film.
Currently figuring out the best way to supply Vref and what cap materials and sizes to use.
At the moment I create 5.25 from an LT3042 that supplies Vdd. This trace then supplies a OPA1611 buffer into the Vref net.
You’ll see the 4 large cans around the AKM. Initially 6SVPC820M, with 0.22uF ish ceramic or FCA film.
Okay, why not...
And what do this transformers exactly? Because of the AK4458 has voltage output: 2x2.8V between the + and - lines.
Do they HF filtering and/or voltage conversion?
A technical question: do you know what the current consumption of the Vref pins are? There are no information about it in the datasheet...
And what do this transformers exactly? Because of the AK4458 has voltage output: 2x2.8V between the + and - lines.
Do they HF filtering and/or voltage conversion?
A technical question: do you know what the current consumption of the Vref pins are? There are no information about it in the datasheet...
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@zarandok: there is no any information about current consumption of the Vref pins at AK datasheet.
Usually, the transformer do the differential->SE stage, plus the gnd isolation between primary side and secondary side.
@sqpu: is there cinemag CM-10100 available in Europe? Can you upload the connection diagram btw the AK output and CM-10100 (2 channel)?
Usually, the transformer do the differential->SE stage, plus the gnd isolation between primary side and secondary side.
@sqpu: is there cinemag CM-10100 available in Europe? Can you upload the connection diagram btw the AK output and CM-10100 (2 channel)?
Thanks!
I've just received my AK4458 pcbs...
Can I have some questions to your design?
- you are using LT3042 regs. The C(set) capacitor is a key part of this, must be low leakage type with 0,47-4,7...uF value. What size (mechanical and value) and type did you plant? (seems to be quiet small...!)
- what type and value are the electrolitics between regs and DAC?
- did you considered the power-up sequence for power supply? (e.g. the 1,8V must be the first!)
- are you using for Vref separate LDOs?
I've just received my AK4458 pcbs...
Can I have some questions to your design?
- you are using LT3042 regs. The C(set) capacitor is a key part of this, must be low leakage type with 0,47-4,7...uF value. What size (mechanical and value) and type did you plant? (seems to be quiet small...!)
- what type and value are the electrolitics between regs and DAC?
- did you considered the power-up sequence for power supply? (e.g. the 1,8V must be the first!)
- are you using for Vref separate LDOs?
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