[b0bb]

  Ok, is the low jitter pulsar clock in the XO table on page 20 of this thread referencing this OCXO below:
 
http://www.pulsarclock.com/Clock.html
 
Or is it referencing another one?
 
(Sorry for all the questions)

Pulsar is the clock I am currently using

 

 

 

[penguin69]

Thanks b0bb.
 
I already have the 9018 datasheet:
 
http://pdf1.alldatasheet.com/datasheet-pdf/view/485882/ESS/ES9018.html,
 
It is somewhat useful but seems very high level.
 
I thought that there might be something more detailed out there. I have been studying this recently: 
 
http://www.customanalogue.com/diy/Stereo_Oppo_Diagram_SMD_Add.gif 
 
But it doesn't clearly state what all the pins do. Anyway, it's not that important. I was just curious in the event that at some later point I might want to try some things out.
 
Thanks as always for the response.

 

[b0bb]

  Thanks b0bb.
 
I already have the 9018 datasheet:
 
http://pdf1.alldatasheet.com/datasheet-pdf/view/485882/ESS/ES9018.html,
 
It is somewhat useful but seems very high level.

The proper datasheet is 35 pages.

 

[penguin69]

Thanks - found it.

 

[penguin69]

   
Post pictures of your LKS and I can take a closer look.
 
If the XO has been put on a separate board thinks are easier,
 
 

 
As requested, here is a picture of the XO on its dedicated board.
 
The board has been installed in a small free area on the main board, not too far from the large 6800uF caps, which are to the left, out of picture. The large white wire in the picture runs to where the XO originally sat on the PCB.
 
This modification should make it easier for me to swop out the XO. I'm not sure if the 14 pin board will help here.  
 

 
 
I've had the unit a week now, and after sounding pretty raw on day 1, it is slowly starting to improve. Partly due to the the op amp rolling no doubt, and partly perhaps due to the fact that the DAC is still burning-in.

 

[b0bb]

   
As requested, here is a picture of the XO on its dedicated board.
 
The board has been installed in a small free area on the main board, not too far from the large 6800uF caps, which are to the left, out of picture. The large white wire in the picture runs to where the XO originally sat on the PCB.
 
This modification should make it easier for me to swop out the XO. I'm not sure if the 14 pin board will help here.  
 

 
 
I've had the unit a week now, and after sounding pretty raw on day 1, it is slowly starting to improve. Partly due to the the op amp rolling no doubt, and partly perhaps due to the fact that the DAC is still burning-in.

 
One of the nice things in the LKS design is the XO is very close to the DAC.
LKS very carefully terminated the XO input to the DAC to avoid the signal bouncing back and forth between the DAC input and the XO output.
In the LKS it is complicated as the signal in split 2 ways.
 
Below is the XO termination in the LKS.

 
Adding a coax cable between the XO and the DAC input changes the relationship, the coax cable capacitance adds a delay that is not constant across the frequency band and this distorts the shape of the square wave coming out of the XO, this affects the performance of the Digital PLL in the DAC.
 
The extra wire also changes the impedance due to the capacitance of the cable, the CCHD-575 is specified to drive only up to 15pF of load and that is not a lot.
The impedance is now mismatched and you will get reflection, this worsens the jitter performance of the XO.
 
This might explain why you are hearing a very harsh output out of the DAC.
 
Here is an example of remote clock line done correctly in the Gustard X20u, the rectangle in green is the line driver to handle the extra load from the coax cable capacitance.

 
The EE Minimax Supreme also places the clock very close to the DAC

 
The stock LT1763 regulator noise is specified at 20uV over 10Hz-100kHz. This gives a noise density of 63nV/√Hz
https://cds.linear.com/docs/en/datasheet/1763fh.pdf
 
Check that Effective Audiomod regulator you are using is better than this number otherwise return to using the stock regulator.
Early numbers from DIYAudio suggest the noise is 1mV over 250kHz, this gives a noise density of 2000nV/√Hz
http://www.diyaudio.com/forums/digital-source/84495-effective-audio-clock-singapore-4.html#post983797

 

[penguin69]

All great information, thanks b0bb.
 
If I take away the auxiliary board and return to the stock topology, then I can use the 14 pin socket approach and try out different XO's, which would be great.
 
I read earlier that you need SMT rework tools to remove the XO in the first place, to prevent warping of the PCB. Obviously, the Crystek XO is out now, but is a similar approach required to install the 14 pin socket? I would need to order proper tools, and probably work up the confidence to remove the whole PCB also. Not impossible of course, but as a neophyte modder I'm just looking at the worst case scenario of me rendering useless a $1500 DAC.
 
I also took a look at the different XO's available. Here in the UK, it's not so easy to get some of these. Maybe I will start with the Crystek 950 as it's affordable and easy to source. Perhaps I am doing something wrong, but my search for the Pulsar XCXO came back with a price of around $400.
 
Thanks again.

 

[b0bb]

  I read earlier that you need SMT rework tools to remove the XO in the first place, to prevent warping of the PCB. Obviously, the Crystek XO is out now, but is a similar approach required to install the 14 pin socket? I would need to order proper tools, and probably work up the confidence to remove the whole PCB also. Not impossible of course, but as a neophyte modder I'm just looking at the worst case scenario of me rendering useless a $1500 DAC.
 
I also took a look at the different XO's available. Here in the UK, it's not so easy to get some of these. Maybe I will start with the Crystek 950 as it's affordable and easy to source. Perhaps I am doing something wrong, but my search for the Pulsar XCXO came back with a price of around $400.

The 14pin socket can be soldered using a conventional iron, post a picture of the area of the XO where the white wire is soldered in to be absolutely sure.
You will need an adaptor for the SMT crystals like the CCHD950. Twisted pear make them.
 
The one in the pictures below is made by Accutek Micro.

 

 
 
 
Key to the soldering exercise is to practice soldering/desoldering on scrap electronics boards, the local electronics recycling centre or local electronics and computer surplus stores is a first starting point.
 
Proper tools are important, try avoiding the cheap $99 specials on Ebay and elsewhere.
In my tool inventory Hakko and Metcal make the mid-range gear, on the top end Pace and JBC make excellent  SMT rework, soldering and desoldering tools.
 
Pulsar is the top of the line XO for the LKS and the price is correct, Crystek 950 is a sane starting point.

 

[penguin69]

Thanks again for the sage advice. I've ordered some better soldering kit, I'll now try to source the oscillator and adapters. I'll leave the more expensive Pulsar xo until I can trust my own handywork a little more.
 

 

  The 14pin socket can be soldered using a conventional iron, post a picture of the area of the XO where the white wire is soldered in to be absolutely sure.
 

 

 
Here's a pic of the board sans XO.
 

 

[penguin69]

Ok, so earlier today I ordered the 14 pin DIP (the one with the unused pins removed, of course). The part cost 0.90 GBP - nice and cheap. But the postage was 13x the cost of the part.  
 
So I ordered 10 pieces, just to make the postage cost not seem so rough. I think my LKS cost about the same in shipping...
 
It seems not that easy to source single instances of XO's over here in the UK. The best bet in terms of availability - and fit - looks like the Abracon AOCJY1. I was about to pull the trigger on this XO through digikey, but I saw that there are several variations, e.g. Sine Wave vs CMOS, 3.3v vs 5v, frequency stability differences, etc. I think there are about a dozen variations in all.
 
b0bb, I see from an earlier post that the one you have is marked: AOCJY1   100.0Mhz  C5C
 
(I will assume that the fc=10.00MHz allocation to this OCXO in post #279 is a typo.)
 
I've noted also in an earlier post that you describe the one you use as rated at +/-50ppb for frequency stability. This narows down the options to four:
 
http://www.digikey.co.uk/product-detail/en/abracon-llc/AOCJY1-100.000MHZ/535-10656-ND/2441422
 
http://www.digikey.co.uk/product-detail/en/abracon-llc/AOCJY1A-100.000MHZ/535-10660-ND/2441426
 
http://www.digikey.co.uk/product-detail/en/abracon-llc/AOCJY1-100.000MHZ-SW/AOCJY1-100.000MHZ-SW-ND/5054802
 
http://www.digikey.co.uk/product-detail/en/abracon-llc/AOCJY1A-100.000MHZ-SW/AOCJY1A-100.000MHZ-SW-ND/5054840
 
I'm guessing it should be the 3.3v model, which would then narrow the options down to 2 - Sine Wave vs CMOS.
 
I will see if I can work out which it is - they aren't that cheap so I don't want to spend money on the wrong item. I'm pretty sure it shouldn't be the Sine Wave one.

 

[b0bb]

Mouser UK has 21pcs of the CCHD950X
http://www.mouser.co.uk/ProductDetail/Crystek/CCHD-950X-25-100000/?qs=%2fha2pyFadugYon81AJBUAqtnwa0B0zdCsX3YXApBu6M%3d
 
The phase noise for the AOCJY1 is for 10MHz, Abracon did not provide any data for 100MHz.
This is an OCXO that requires special handling, not recomended as a starter device.

 

[penguin69]

Thanks b0bb - I was favoring the Abracon largely because the fit seemed nicely compatible for the DIP adapter. I'll avoid it based on your advice.
 
I'll order the CCHD950X now. I very nearly ordered it from mouser before, I only held back because I was struggling to locally source the additional adapter board which you recommended.
 
If I can't easily get that, I'll get it to work by other means. 

 

[penguin69]

  The 14pin socket can be soldered using a conventional iron, post a picture of the area of the XO where the white wire is soldered in to be absolutely sure.
You will need an adaptor for the SMT crystals like the CCHD950. Twisted pear make them.
 
The one in the pictures below is made by Accutek Micro.

 

 
HI again b0bb,
 
I found the Accutek adaptors, but the company don't appear to have an online store - did you source yours from them by e-mail?
 
The Twisted Pear Audio site shows no sign of xo adaptors (unless I'm missing something).
 
http://twistedpearaudio.com/landing.aspx​
 
Sorry to be a pain. I thought it might be somewhat easier to source these items. Are there so few DIY'ers out there?
 
On a separate note, do you have a preferred front end for your LKS? I used a Raspberry Pi with MPD for about 3 years, running the USB out into a cheap PCM2704 converter and then optical into my old DAC (another older EE Minimax). I loved the fact it could play lossless with just 2% CPU usage, and I could leave it running for months without crashing. I recently switched to a Mac Mini for ease of use with Tidal, and so the connectivity is now via USB. For some reason I miss Toslink; I always found it sounded great despite the reported jitter issues with Toslink tranceivers. 

 

[penguin69]

 
I cooked my Dexa op amps yesterday by mistake, so installed on the output stage the old Burson duals which came as an add-on with a previous DAC. They sound pretty good. They are too tall to fit the LKS unit with its lid on.

 

[b0bb]

http://twistedpearaudio.com/digital/cronus.aspx

   
HI again b0bb,
 
I found the Accutek adaptors, but the company don't appear to have an online store - did you source yours from them by e-mail?
 
The Twisted Pear Audio site shows no sign of xo adaptors (unless I'm missing something).
 
http://twistedpearaudio.com/landing.aspx​
 
Sorry to be a pain. I thought it might be somewhat easier to source these items. Are there so few DIY'ers out there?
 
On a separate note, do you have a preferred front end for your LKS? I used a Raspberry Pi with MPD for about 3 years, running the USB out into a cheap PCM2704 converter and then optical into my old DAC (another older EE Minimax). I loved the fact it could play lossless with just 2% CPU usage, and I could leave it running for months without crashing. I recently switched to a Mac Mini for ease of use with Tidal, and so the connectivity is now via USB. For some reason I miss Toslink; I always found it sounded great despite the reported jitter issues with Toslink tranceivers. 

 
Contact Accutek directly, the boards are made to order, takes about 2 weeks.
 
The part is 4 Pin SOJ Crystal to 4 Pin(14 Pin Full Size) 300 MIL DIP AK14D300-XTAL-04SOJ

 
Twisted Pear's adapter is the Rhea, scroll down towards the end of the page
http://twistedpearaudio.com/digital/cronus.aspx
 
I use the Logitech Music server (LMS) and Squeezelite combo.
Squeezelite is run on the Raspberry Pi2 (Picoreplayer)  and  Odroid C1+ (Max2Play)
 
Rpi2s on the left  Odroid C1+ on the right, Odroid has the benefit on not sharing the USB with the ethernet, sound quality especially imaging is considerably better