AppleTV X - I am playing with something new

AngeloVRA

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Mar 8, 2020
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Hi @Xymox
Thanks again for the additional tips. Im happy enough with what the AN Kaisei does, that I will probably leave it in.
For a possible bypass MKP10 would probably be a better candidate but I have only Wima MKP4 0.1uf/100v in my spares. I'll probably try them after giving the current caps 1-2 weeks to settle down and show their true "colors" :)

And yes, in my experience the LPS used has a substantial impact. I currently use a 12v/6A rail from my PH SR5T LPS with Mundorf AG electrolytic and AN Kaisei output caps.

I do have a Tektronix 2465BDM but long leads to the apple PCB would pick up spurious noise and probably lead me to the wrong conclusion. Also, my objectives for the Apple TV are modest.
 

Xymox

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I do have a Tektronix 2465BDM but long leads to the apple PCB would pick up spurious noise and probably lead me to the wrong conclusion.

The power connection is really low impedance, so, some dangley thin wires wont pick up noise, sorta mostly, BUT, The ground of the scope connected to the ground of AppleTV would surely induce noise.

Yes i forgot about that, I use a differential 7A22 plug-in and so don't have a ground connection during measurements. ALSO the noise measurement is so low most likely the 2465 might not be that useful at 2mV/div :( , the 7A22 goes down to 10uV/div.

Your right.
 

Xymox

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A whole new level.. In R&D right now, but moving forward in the weeks to come.. Of course I will upgrade existing units once its all ready.


Untitled-1.jpg
 

Billinge

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Aug 15, 2021
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Hi
A whole new level.. In R&D right now, but moving forward in the weeks to come.. Of course I will upgrade existing units once its all ready.


View attachment 93604

A whole new level.. In R&D right now, but moving forward in the weeks to come.. Of course I will upgrade existing units once its all ready.


View attachment 93604

Hi

Just an obvious question when reading this, rather than trying to cram everything into a small footprint plastic case, why don't you take the circuit boards out and put them in a new copper shielded case with high quality connectors etc. Then you would have more room? The power supply could be a bit more isolated etc
 

Xymox

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Apr 17, 2019
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Hi

Just an obvious question when reading this, rather than trying to cram everything into a small footprint plastic case, why don't you take the circuit boards out and put them in a new copper shielded case with high quality connectors etc. Then you would have more room? The power supply could be a bit more isolated etc

Great question...

The AppleTV board is sandwiched between 2 thick metal blocks. These do a number of things. Mostly they are precision made to press on each chip on BOTH side of the board and act as heatsinks. They also have serious and really good RF shielding complete with RF gaskets right to the boards. These create NICE RF cavities with 1/4" aluminum blocks as shielding. Its actually a wonderful design. Its very well thought out.

It would be challanging to equal. The PC board itself also has a abnormally think center ground plane and power plane. This does some really good isolation between the bottom and top parts and allows thru the needed connections in a RF controlled way..

It reminds me of a how really good RF test equipment is made with cavities and thick metal.

I would LOVE to get the board out. BUT.. I think this would degrade performance. It would require some custom heat pipe based heat sinks and would just not be as good as what they did..

WHile Apple was NOT intending for epic esoteric performance, they did the metal for heat sink reasons, what they did with the small size, the incredible layout and the use of the smallest SMD parts turned out to be kinda miraculous with the right changes..

I have spent a crazy amount of time inside this tiny space and I think the way apple did it, is clearly the best way for performance. They never considered this level of performance as a goal, but, that is what has happened.

I have some spectrum measurements I recently did I will post.. I have used a LOT of careful tuning and sucked huge amounts of noise from the unit.. This vast noise reduction and use of a remote sensing linear with high precision have resulted in a "jaw dropping" picture and sound that clients describe as "insanely good"..

There is a review in progress.
 
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Xymox

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STOCK AppleTV.. 12 V power rail.. This noise COMES FROM the AppleTV itself. The CPU, HDMI EThernet chips all generate noise. So I spent WAY too much time and addressed each band of noise with specific caps and tuned circuits. This apsect of the changes was the most time consuming. Things like lower phase noise on the clocks and providing a far more precision supply was easy..

Fixing the noise on the board was REALLY hard..

This is the stock AppleTV.. Spectrum Analyzer is calibrated. This is 9khz to 350khz. The main noise. Mostly generated by the buck/boost regulators on the board.

1654148421027.png

_____________________________________________________________________________________________________

The below plot is from a unit I am QCing for shipment. I check this on each unit..

Same scale. Same everything.. The green line is -90db..

This VAST noise reduction required stupid amounts of work.. It required using solid silver wire of a specific ga with very specific caps arranged in a precision way along the wire. A PC board solution sucked. GONE are all the nasty harmonics and all the,,, junk..

Remember,, this noise comes from the AppleTV board. This has pretty much nothing to do with a linear or power supply. The appleTV power supply is mostly clean output.. BUT it cant address the noise on the ATV board. You gotta do that with HIGHLY tuned parts that will fit inisde the ATV.

1654148512305.png
 
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Billinge

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Great question...

The AppleTV board is sandwiched between 2 thick metal blocks. These do a number of things. Mostly they are precision made to press on each chip on BOTH side of the board and act as heatsinks. They also have serious and really good RF shielding complete with RF gaskets right to the boards. These create NICE RF cavities with 1/4" aluminum blocks as shielding. Its actually a wonderful design. Its very well thought out.

It would be challanging to equal. The PC board itself also has a abnormally think center ground plane and power plane. This does some really good isolation between the bottom and top parts and allows thru the needed connections in a RF controlled way..

It reminds me of a how really good RF test equipment is made with cavities and thick metal.

I would LOVE to get the board out. BUT.. I think this would degrade performance. It would require some custom heat pipe based heat sinks and would just not be as good as what they did..

WHile Apple was NOT intending for epic esoteric performance, they did the metal for heat sink reasons, what they did with the small size, the incredible layout and the use of the smallest SMD parts turned out to be kinda miraculous with the right changes..

I have spent a crazy amount of time inside this tiny space and I think the way apple did it, is clearly the best way for performance. They never considered this level of performance as a goal, but, that is what has happened.

I have some spectrum measurements I recently did I will post.. I have used a LOT of careful tuning and sucked huge amounts of noise from the unit.. This vast noise reduction and use of a remote sensing linear with high precision have resulted in a "jaw dropping" picture and sound that clients describe as "insanely good"..

There is a review in progress.
Fascinating, Does heat play a significant part in the equation. I just have my 2017 apple tv 4k sitting on a blob of blutak next to my UB9000 to give the fan extra clearance
 

Billinge

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Great video. Last apple tv I took apart was the original gen 1 with a hard disk, certainly changed since then.

I hope you cleaned the old heatsink paste off and replaced with new high performance paste/pads (I'm building a top end water cooled pc, water cooled gpu etc)
 

Xymox

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Fascinating, Does heat play a significant part in the equation. I just have my 2017 apple tv 4k sitting on a blob of blutak next to my UB9000 to give the fan extra clearance

No.. I asume it can get hot because of the heatsink and fan. I have been unsuccessful in making it draw more then 500mA. During streaming it draws 200 mA avg. It barely gets warm. There must be some apps, maybe gaming, that use a lot of CPU, but nothing I have found so far uses anything that causes the fan to spin at all and it barely gets warm.

During screen saver, power saver turned off, it only draws 70 mA. I dont know why they have a power saver as it draws so little power.
 
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Xymox

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Great video. Last apple tv I took apart was the original gen 1 with a hard disk, certainly changed since then.

I hope you cleaned the old heatsink paste off and replaced with new high performance paste/pads (I'm building a top end water cooled pc, water cooled gpu etc)

Oh yea.

The thermal paste they use is ok, but I put on much better paste that has even better electrical and thermal characteristics. Its a bit tricky, not like normal thermal paste. On the bottom side below the A12 they use it right on SMD parts like resistors and caps. I had never seen that before and so it was important to look at electrical properties of the paste as it just slops onto the parts. Turned out that technique is more common then I thought and there are specific pastes for that use. Its not the resistance of the paste, its the capacitance of the paste at high frequencies that is important.. So slapping just any paste on it is a bad idea.
 

Billinge

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Oh yea.

The thermal paste they use is ok, but I put on much better paste that has even better electrical and thermal characteristics. Its a bit tricky, not like normal thermal paste. On the bottom side below the A12 they use it right on SMD parts like resistors and caps. I had never seen that before and so it was important to look at electrical properties of the paste as it just slops onto the parts. Turned out that technique is more common then I thought and there are specific pastes for that use. Its not the resistance of the paste, its the capacitance of the paste at high frequencies that is important.. So slapping just any paste on it is a bad idea.

If you take apart your nvidea 3090 and other top spec gpu's to water cool you see they have the liquid stuff on the gpu itself and putty like thermal pads on the other solid state components, you can buy it from pc water cooling supplies eg https://www.ekwb.com/shop/thermal-pad-f-2-0mm-120x16mm (especially if you overclock for crypto mining), I'm assuming the gpu is working at much higher frequencies?
 

Xymox

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If you take apart your nvidea 3090 and other top spec gpu's to water cool you see they have the liquid stuff on the gpu itself and putty like thermal pads on the other solid state components, you can buy it from pc water cooling supplies eg https://www.ekwb.com/shop/thermal-pad-f-2-0mm-120x16mm (especially if you overclock for crypto mining), I'm assuming the gpu is working at much higher frequencies?
Oh yea. I know about overclocking having a nice rig myself and I do tons of work and restore work on things where thermal paste and pads are used. In my view pads are never as good as a good paste. But pads are used where you cant have the material creep, or you need to insulate the device from the heat sink OR more likely as a labor saving method.

Most of the pastes used for almost all uses are designed for thermal use as its main objective and some, like the silver content ones, assume it will never touch actual conductive parts. In fact, silver pastes can be dangerous if not used correctly.

The ATV is very different. They used a special grease. It stays more liquid like then a paste. Its made to touch conductive parts working at high frequencies. Picture taking a whole mother board and covering everything in a goo. Then clamping metal blocks on both sides. So every part and every pin on everything is submerged in the goo. You gotta be sure all the parts dont have goo soak into them and you gotta be sure the goo does not affect the parts in any way electrically.

Its really different then doing stuff on a motherboard.

I was kinda stunned the first time I saw all this goo all over parts inside the appleTV. But after research I found out its a pretty slick way of getting heat away. Also its cool because it can make the board and all the parts the same temp. The goo along with the thick metal act to thermally stabilize the whole board.

The goo can also have RF absorbing properties.

It may look sloppy and messy, but, its a great idea by Apple and adds to performance.
 
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Xymox

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I have been playing with Linears. Mods are good.

20uV pk-pk ( 5uV RMS ) noise under 1.8A load and all low freq. 14Vdc +- 0.0002 over 24 hrs. Reg stays locked 85Vac line in to 135V. Impeadance so low I can't measure it up to 100Khz. Impressive transient response. Full wideband remote sensing + & -..

Just what a AppleTV ( or phono stage ) needs..

LNPower.jpg
 

Xymox

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I have completed the new linear mods to work with the AppleTV X. I did a number of tweaks AND added 2 wire sensing/feedback. I now sense the voltage and noise inside the AppleTV X. This results in a VAST improvement in regulation and noise reduction right on the AppleTV board. I started with a R-Core transformer and all the normal fun audio tweaks and added the sensing circuits. I put a 4 pin connector on the back. That is +- and +- sense. I now ship the AppleTV X with this package and am upgrading existing customers free.

Along with this linear comes some upgrades to the ATVX. There was even finer tuning of the cap bank and a complete rework of the link from the cap back to the AppleTV PCB that involved creating a litz arrangement of fine ga high purity silver.

SO.. I will spend a week testing it and abusing it all and then start selling them as a set in about 7-10 days. I will be upgrading existing existing clients first with advance replacement units so no down time, just send the old ones back.

Pretty exciting for me.. I am finally done with the whole plan I had.

IMG_6203.JPG
IMG_6180.JPG IMG_6181.JPG
 
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Tuckers

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Hey good job there! I can concur that working with the power supply on these media streamers makes a significant difference. I don't do Apple, though I have thought of trying one recently. I use an Nvidia Shield with some power supply and rf reduction tweaks. I also have major power treatment on my system that improves it and the results from my tv.

You haven't done anything to improve stereo output with it? Assuming that you would still need an optical output either from the TV, or with an hdmi audio converter (barring the use of a very expensive pre processor).

I run a glass toslink from my TV to a Beringer DEQX, where I have developed a number of EQs to suit my tastes for different video player apps and streaming. Then to my May KTE dac (which does an excellent job of cleaning up Toslink).

Your price is beyond what I would spend on my video input though, justified as it appears to be.

Curious why you didn't rehouse the electronics in a bigger chassis, with the potential for even less interference?
 

Xymox

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Hey good job there! I can concur that working with the power supply on these media streamers makes a significant difference. I don't do Apple, though I have thought of trying one recently. I use an Nvidia Shield with some power supply and rf reduction tweaks. I also have major power treatment on my system that improves it and the results from my tv.

You haven't done anything to improve stereo output with it? Assuming that you would still need an optical output either from the TV, or with an hdmi audio converter (barring the use of a very expensive pre processor).

I run a glass toslink from my TV to a Beringer DEQX, where I have developed a number of EQs to suit my tastes for different video player apps and streaming. Then to my May KTE dac (which does an excellent job of cleaning up Toslink).

Your price is beyond what I would spend on my video input though, justified as it appears to be.

Curious why you didn't rehouse the electronics in a bigger chassis, with the potential for even less interference?

The SQ coming from it doing pure 2 channel from sources like a audio file server, iTunes, Tidal or even youtube music vids is off the hook compared to a stock unit. Sound quality was the main goal. I have some reviews coming out that discuss this vast improvement in SQ.

Just today I was over at someones home who is a new owner and we were just stunned at the SQ. YES the ATVX shocks me too. The imaging was amazing, big wide deep and very defined. Delineation of instruments was amazing. It was highly detailed with amazing textures for everything. It was fast, but not bright. VERY natural. Its presence was remarkable.

I have 2 clients who are using it as their prime music streaming device. They use various devices to get the HDMI over to SPDIF/Optical and then feed that to high end DACs. They use a high quality networking switch. One is using a SoTM and a external clock. They are using high end cables for HDMI, power and ethernet.

There is a hidden setting. Apps > Music > Quality>Lossless.. It does not come default lossless. I believe this applies to music played via the music app.

There is a weird way to make it into a roon device. It can even control roon. I have not tried this.

Using the ATVX as a high end music streamer could be a whole different interesting angle to explore. I would have never imagined a HDMI device could produce high quality sound, but, I have now heard 3 different clients systems doing this and it was fairly shocking. Is it a Taiko / Wadex ? of course not, BUT its a LOT better then anything I would have imagined.

There is a reviewer who is playing with high end ethernet switches and will discuss it in a review.

Curious why you didn't rehouse the electronics in a bigger chassis, with the potential for even less interference?

The ATVX is a nearly perfect RF enclosure with RF tight gaskets and 1/4" solid metal blocks for RF shielding. Its a nearly perfect enclosure :)


A lot of the work I make public is covered in this page. There is a bunch of secret sauce i don't make public tho too. See link below.

 

Tuckers

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I used to design high end computer audio systems, so I know how true the phrase "everything matters" in sound design. From the brand of memory to even testing individual memory boards to find the best sounding one in a batch, or how tight the screws are connecting the motherboard to the case, everything makes a difference. Our group was the first to use transformer based decoupling and fiber bridges etc on ethernet to improve SQ. Of course everyone back then thought we where nuts! That was one of the fundamental things we did to make computer based audio better.

I use special Cat8 cabling (selected by listening tests), a high quality switch to a fiber bridge with every component using linear power supplies (non audiophile off the shelf LPS though) to my quality Roon endpoint. Makes a difference. I haven't put my Shield on a fiber bridge yet though. Can't easily use an LPS with it, it has a special cable. But I get really high quality video from the Shield and TV though.

I am less concerned with audio from my video source (especially since I only do stereo) , because most audio is arbitrarily downmixed to stereo in who knows what way on a per file basis, and audio quality in most videos is really poor to begin with. When you have a quality setup you start to notice how poor at least 90% of audio tracks are on TV shows, Youtube etc. Stereo audio has become an afterthought for all video devices these days including the Apple TV. A lot of this is because of Dolby licensing. Buying the proper license to downsample Dolby surround to stereo properly is super expensive, only the TV ccompanies can afford it.
 
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Xymox

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I used to design high end computer audio systems, so I know how true the phrase "everything matters" in sound design. From the brand of memory to even testing individual memory boards to find the best sounding one in a batch, or how tight the screws are connecting the motherboard to the case, everything makes a difference. Our group was the first to use transformer based decoupling and fiber bridges etc on ethernet to improve SQ. Of course everyone back then thought we where nuts! That was one of the fundamental things we did to make computer based audio better.

I use special Cat8 cabling (selected by listening tests), a high quality switch to a fiber bridge with every component using linear power supplies (non audiophile off the shelf LPS though) to my quality Roon endpoint. Makes a difference. I haven't put my Shield on a fiber bridge yet though. Can't easily use an LPS with it, it has a special cable. But I get really high quality video from the Shield and TV though.

I am less concerned with audio from my video source (especially since I only do stereo) , because most audio is arbitrarily downmixed to stereo in who knows what way on a per file basis, and audio quality in most videos is really poor to begin with. When you have a quality setup you start to notice how poor at least 90% of audio tracks are on TV shows, Youtube etc. Stereo audio has become an afterthought for all video devices these days including the Apple TV. A lot of this is because of Dolby licensing. Buying the proper license to downsample Dolby surround to stereo properly is super expensive, only the TV ccompanies can afford it.

Yea I thought TV audio was all garbage too. Not any more. Clients now describe TV audio using terms they normally use with high end DACs and turntables. As you say, It all matters. Dejittering everything from the ethernet rcvr to the CPU/RAM to the A12 busses and HDMI all combined to produce kinda stunning audio. Audio packets are all interleaved into the video data and its just really hard to get all that right. Video on HDMI is hard enough, but, the audio is stuck in kind sideways into the video stream and even harder to get out.

I think a good audio system can reach down into a bad recording and pull out a enjoyable experience and that is exactly what seems to be occurring.

Commercials can be just stunning audio quality. Its really crazy going from a show, to a set of commercials as each commercial is SO stunningly different sounding. Each show/movie has just day/night difference channel to channel, app to app. Things used to kinda all sound the same. Boring, lifeless.. Now EVERYTHING sounds completely different - as it should. Everything is quite listenable and can jump all the way to a high end DAC level of experience depending on the show.

Reviews will cover the huge jump in SQ over any other HDMI source. The vastly lowered noise floor on the HDMI also a very clean TMDS and the dejittering and lowered noise for all the chips and systems on the entire ATV platform all combine to produce a result that really defines a sum of all its indiv parts.
 

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