Adjusting screw tightness on Esoteric K1X helps a lot!

Sablon Audio

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If the disc tray is silver, like my old x-01, then covering with black self adhesive felt or vinyl will improve sound quality.
 

AMR / iFi audio

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If the disc tray is silver, like my old x-01, then covering with black self adhesive felt or vinyl will improve sound quality.
Maybe paint it with the blackest paint in the world?
It's probably aluminium, so it might not stick, though.
 

Blue58

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Jan 20, 2013
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Maybe paint it with the blackest paint in the world?
It's probably aluminium, so it might not stick, though.
https://www.mjkzz.de/products/musou-black?variant=38002526191799

even blacker!
 

AMR / iFi audio

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You're right, but it might flake off when CD is being put on it:
"Due to the powdery light absorption layer, the strength of the coating is very low, so glossing and peeling of the coating will occur even with light contact. The painted object may shrink and crack."

But not easily reversible :(
Right, the tape is much easier to be cleaned up. It's really down to how hard you want to go on your CD player. Still, painting CD tray is not as intrusive as replacing an opamp :)
 

diaZ

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Dec 30, 2019
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OPA627 is an excellent FET input device, thus it has a very low input current. How are you seeing it as a benefit in this application? Is the DAC output or feedback resistors high impedance?
The biggest pro of discrete opamps is a two-pole compensation, which is impossible to do in an IC. Two-pole compensation allows the opamp to have much more feedback at high frequencies (say 10k+), offering better distortion reduction. Sparkos has an excellent blog post about it, I believe, you'll love it: https://sparkoslabs.com/discrete-op-amps/audio-op-amps-gain-seek-bandwidth/
He makes excellent opamps too.

As for sockets, you are absolutely right. They add inductance and physical distance to the decoupling capacitors. It has the biggest effect on power supplies. Most discrete opamps have their own decoupling on board, so it's not that big of an issue.

I'm very curious to hear from you about that. It's a very interesting discussion!
Yes, you are right, an endless and super interesting field. A bit like cooking for different tastes. But we can agree that the NE5534 is best to be exchanged, and that it can be easily done. So I personally dont fear warranty problems and never had one.
And you are right also with the importance of the capacitors for the OP amp supply. Thank you for your feedback!
 

AMR / iFi audio

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Yes, you are right, an endless and super interesting field. A bit like cooking for different tastes. But we can agree that the NE5534 is best to be exchanged, and that it can be easily done. So I personally dont fear warranty problems and never had one.
And you are right also with the importance of the capacitors for the OP amp supply. Thank you for your feedback!
NE5534 is a great part, but its contemporary counterparts are way better.
OPA627 is miles better. I was surprised to see it's still available at big distributors, like Mouser. Do you know any other JFET opamp that is as good?
In our products, like iDSD NEO we use opamps developed for us. They are called OV2637A and OV4627A, which you can see here. What a coincidence, huh? ;)
 
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diaZ

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Hi! Fine to meet someone who is also heavily engaged in audiophile parts. Obviously you know more about available OPamps than me.
Are you a part of the R&D team of ifi audio?
Yes,, I order from Mouser, parts come direct from Texas. OPA627 has laser trimmed input resistors for the ultra low Ib.
This is important in filter design for minimal load of the 12 dB RC filters Esoteric is using. The OPA 627 is selected in specs and the BP grade is better than the AP grade.
 
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AMR / iFi audio

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Hi! Fine to meet someone who is also heavily engaged in audiophile parts. Obviously you know more about available OPamps than me.
Are you a part of the R&D team of ifi audio?
Yes,, I order from Mouser, parts come direct from Texas. OPA627 has laser trimmed input resistors for the ultra low Ib.
This is important in filter design for minimal load of the 12 dB RC filters Esoteric is using. The OPA 627 is selected in specs and the BP grade is better than the AP grade.
I'm not from RnD, I just know a thing or two about electronics :) I believe that you can use a bipolar input opamp in this place without the fear of disrupting the filters (which is what Esoteric did). We can do simple guesswork about the filter. This is a low-noise circuit, which implies the filter must have a low impedance to avoid Johnson (thermal) noise.
I'm expecting the resistive part of the filter to be in the realm of 1-3 kOhms. It's a good compromise between loading the previous stage and low noise. Comparing the filter's impedance of single kiloohms to the input impedance of JFET (<1 GOhm) and bipolar (<1 MOhm) opamps, we can see it's can't affect the filter's performance.
A bipolar opamp might be slightly preferred in this place because it works better with low impedance sources. that doesn't mean that OPA627 can't sound incredible in this place.
 

diaZ

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Hello AMR / iFi audio,
It is a two stage 12 dB Filter with 1.8kOhm and 470 pF followed by 5.6kOhm with 100 pF, Feedback resistor is 2,4kOhm, so the gain is a little over 1, perfect for OPA627.
Im sorry, Im not engaged in physical theory of OP amps and dont know much about it. So I depend on what I can hear, and for my personal individual taste the OPA627 is the best I ever had in filter stages.
And maybe Im adapted too much to this sound that I know so good, that Im spoiled for testing further OPamps.
My point was for the K-03XD owners to think about replacing the NE5534. And for the OPA627 I know it is worth to be done.
 
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AMR / iFi audio

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Hello AMR / iFi audio,
It is a two stage 12 dB Filter with 1.8kOhm and 470 pF followed by 5.6kOhm with 100 pF, Feedback resistor is 2,4kOhm, so the gain is a little over 1, perfect for OPA627.
Im sorry, Im not engaged in physical theory of OP amps and dont know much about it. So I depend on what I can hear, and for my personal individual taste the OPA627 is the best I ever had in filter stages.
And maybe Im adapted too much to this sound that I know so good, that Im spoiled for testing further OPamps.
My point was for the K-03XD owners to think about replacing the NE5534. And for the OPA627 I know it is worth to be done.
The most important thing is that you are sharing your experience with the community :) Modding is often a good way to improve specific devices if you are okay with losing your warranty. That's always a tradeoff. Alternatively, some folks wait until the end of the warranty period, before moding.
 
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