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ES9018K2M, ES9028Q2M, 9038Q2M DSD/I2S DAC HATs for Raspberry Pi
ES9018K2M, ES9028Q2M, 9038Q2M DSD/I2S DAC HATs for Raspberry Pi
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Old 5th December 2017, 12:26 PM   #61
iancanada is offline iancanada  Canada
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ES9018K2M, ES9028Q2M, 9038Q2M DSD/I2S DAC HATs for Raspberry Pi
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Originally Posted by abraxalito View Post
Of course there is - if you look at the schematic directly above your post, to get a balanced output you'd take the two complementary phases from pins 7 and 10. Pins 6 & 9 would go to GND.
Thanks abraxalito, that's perfect answer.

Actually option1 has no DC current passing through while all the other options have balanced DC offset current (DC current of option4 might be very small). The working conditions are totally different. What's your point at different options?

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Ian
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Old 5th December 2017, 06:58 PM   #62
markusA is offline markusA  Sweden
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Looking forward to listening impressions.
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Old 7th December 2017, 11:22 AM   #63
diyaudnut is offline diyaudnut  United States
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Thanks Ian, Abrax

Another theoretical question to improve my understanding. Could you comment on the pro/cons between an active IV stage and one using an xformer.

What output signal level is achievable with a transformer.

thanks
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Old 7th December 2017, 11:35 AM   #64
abraxalito is offline abraxalito  United Kingdom
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As far as I can see, strictly speaking the transformer's not doing I/V here - its doing output isolation and gain matching/balancing. To be an I/V stage it'd need to present a very low impedance to the DAC chip.

That said, an active I/V stage could be used together with a transformer. For an example of an active I/V look no further than the NTD1 project - opc's NTD1 project
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Old 7th December 2017, 01:13 PM   #65
iancanada is offline iancanada  Canada
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ES9018K2M, ES9028Q2M, 9038Q2M DSD/I2S DAC HATs for Raspberry Pi
Quote:
Originally Posted by abraxalito View Post
As far as I can see, strictly speaking the transformer's not doing I/V here - its doing output isolation and gain matching/balancing. To be an I/V stage it'd need to present a very low impedance to the DAC chip.

That said, an active I/V stage could be used together with a transformer. For an example of an active I/V look no further than the NTD1 project - opc's NTD1 project
Thanks Abraxalito,

Yes, it's true. ESS DACs are not in pure current output mode. The output stage is a voltage source in serial with internal resistance. It can only be considered as current output when load impudence is closed to zero.

How about using a pair of OPA861 to convert ESS outputs into balanced current source, than into a transformer?

Thanks for the link . Actually I bought a NTD1 KIT years ago. But I have been too busy to build it. Maybe it's the time to give a try.

Regards,
Ian

Last edited by iancanada; 7th December 2017 at 01:18 PM.
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Old 7th December 2017, 01:34 PM   #66
abraxalito is offline abraxalito  United Kingdom
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OPA861 would certainly do the job and its got a good reputation for I/V duty as far as I'm aware. I'd be a bit concerned though about its 3rd harmonic distortion figure, given that one of the things attracting customers is ESS's very low THD+N numbers, these might be thrown out the window by attaching an OPA861. The DS only shows 2nd/3rd harmonic at 5MHz so its anyone's guess how much better it'll be at audio freqs.

Also is OPA861's 10ohm input impedance low enough to be considered 'current mode' from the point of view of the DAC chip?

My own reservations with the NTD1 are that its such a power hog - I've an I/V stage where I'm running much lower quiescent currents and much lower supplies but its operation is very similar to NTD1's. There are more recently released MOSFETs which look to provide very high gm at quite reasonable output currents. SSM3K339R is one such but being sot23 it cannot dissipate much power.
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Old 7th December 2017, 03:28 PM   #67
zek is offline zek
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You can use Lundahl LL1684 direct on ES output, like this
http://www.audiodesignguide.com/DAC3...84-for-DAC.jpg
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Old 7th December 2017, 06:22 PM   #68
markusA is offline markusA  Sweden
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IMHO people are biased against transformers because itís too simple.
Judging by my current setup with a ESS9018 and Lundahl transformers, I can crank it up to nosebleed levels with ease and I have it hooked up in 2:1 mode. Most people probably donít need more than the output delivered from the chip. It isolates the circuit and balances it. If you need it you can multiply the voltage upwards.
Silicon might be able to artificially create beneficial load conditions but youíre comparing a piece of wire with a silicon network. I put my trust in the piece of wire...
Iím not saying that itís the end all be all, but it shouldnít be overlooked just because itís a super simple passive solution.
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Old 7th December 2017, 07:11 PM   #69
iancanada is offline iancanada  Canada
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ES9018K2M, ES9028Q2M, 9038Q2M DSD/I2S DAC HATs for Raspberry Pi
Quote:
Originally Posted by markusA View Post
IMHO people are biased against transformers because it’s too simple.
Judging by my current setup with a ESS9018 and Lundahl transformers, I can crank it up to nosebleed levels with ease and I have it hooked up in 2:1 mode. Most people probably don’t need more than the output delivered from the chip. It isolates the circuit and balances it. If you need it you can multiply the voltage upwards.
Silicon might be able to artificially create beneficial load conditions but you’re comparing a piece of wire with a silicon network. I put my trust in the piece of wire...
I’m not saying that it’s the end all be all, but it shouldn’t be overlooked just because it’s a super simple passive solution.
Hi markusA,

My ES9018K2M/9028Q2M/9038Q2M will have RAW balanced output. So they will open to all different kinds of I/V stage as daughter board or at external.

I did a transformer I/V for my TDA1541A DAC when I was working on my tube pre amp project many years ago. It was very impressed.

Magnetic gears have magic to sound quality. Rail to Rail, MM/MC, tube amplifier with input/output transformer, they all sound fabulous, that's the reason.

I'll try transformer I/V stage for this project for sure. I'll post update once I have. Please also let me know if there is any suggestion or recommendation.

Regards,
Ian

Last edited by iancanada; 7th December 2017 at 07:21 PM.
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Old 7th December 2017, 07:28 PM   #70
markusA is offline markusA  Sweden
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Default Design DSD/I2S DAC HATs for Raspberry Pi, start from ES9018K2M

Itís all quite an enigma. Op amps measure great, but for some reason they seem to lack some magic ingredient? Going by measurements alone, they would be hard to beat, but once you stop comparing technical data, your ears often tell a very different tale. Itís both frustrating and what makes hifi so special, all at once.
I have a very interesting tube circuit somewhere on the hdd but it would be sweet with a good discrete solution as well. Either way, I think buffer and fully balanced outputs is a good goal. Gain isnít really needed unless you have a very low amplifying amp.
My tube circuit was fully balanced with a Russian version of the ecc88, thatís the name of the tube, right? Not schoolbook balanced but sort of a sneaky dirty way, lol.
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Last edited by markusA; 7th December 2017 at 07:32 PM.
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