XONAR STX e Vanguard TCXO: disappointment - diyAudio
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Old 16th December 2011, 08:42 AM   #1
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Default XONAR STX e Vanguard TCXO: disappointment

Hello everybody,

I have a XONAR STX for my home system, and after numerous tweaks and mods, I finally reached an impressive sound quality

If someone is interested I can post later the list of my mods

Last week I decided to try the last big change: upgrade the oscillator

I bought from ebay a Vanguard TCXO 0.3 ppm, available from an Hong Kong vendor

I saw many post on the Net about the quality of this oscillator, and the benefit it brings on this sound card vs the stock oscillator

I installed it following example and recommendation found on many forums about this specific item, output pin soldered on pad 2 of the old oscillator, power supply taken from on board 7805

I have to say in my case the result is not satisfing at all, a step backward in the overall sound quality

The sound becomes dull, sterile, the music turned gray and uninvolving, and fatiguing after a while, with metallic flavour voices and harsh sibilant

I tried to supply the oscillator with a dedicated ultra low noise PSU instead of the onboard 7805 , but things doesn't improve

Restoring in place the stock oscillator gives definitely a better result

I can't understand the reason for this behaviour, I can't measure it, but it seems the vanguard XO exhibit an higher jitter than stock one

Playing a test tone, sine wave 11.025 Hz, while with the stock quartz the sinusoid plotted on the screen is not very stable, peaks seems to oscillate in the horizontal axis, with the vanguard the sinusoid is moving crazy like a snake...

I noticed the stock XO on my STX is marked IT405, and all pictures found on the NET show IT475, maybe ASUS has replaced this component with a better one in recent items?

Any idea, suggestion, please

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Old 16th December 2011, 07:36 PM   #2
qusp is offline qusp  Australia
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how are you connecting the output to the dac or ASRC? improperly terminated clocklines even over short distances will often make matters worse than onboard properly terminated, properly grounded lines
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Old 16th December 2011, 10:23 PM   #3
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Following instructions posted by other people that successfully applied the mod, I removed the stock quartz, a 2 pole SMD, and connected the output pin of the vanguard to the second pad (the one on the right side left free after removing the quartz)

There are some pictures on the net, Xonar Essence ST reclocking (tcxo mod)
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Old 16th December 2011, 10:34 PM   #4
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I followed instructions posted by other people who successfully applied the mod

I removed the stock oscillator, a 2 pin smd quartz, and connected the second pin pad on the PCB to the output of the new oscillator

The Vanguard has 4 pins, 5V, GND, output and one not used
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Old 21st December 2011, 03:23 PM   #5
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Hi Robyonekenoby... I am looking for performance review of Asus Xonar essense STX sound card. Please post your list of mods and also your comparison with any other source you have

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Old 22nd December 2011, 09:27 PM   #6
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1) Replaced NJM 2114 in I/V with LM4562
2) Replaced 2.7n film caps in output stage feedback loop with wima MKP 3.3n
3) Replaced electrolytic output caps with a LPF made of 150 ohm resistor and 2.2n cap
4) added wima FKP 3.3u to opamp bypass caps
5) added nichicon fpcap for 5V bypass
6) added nichicon FpCap and ferrite core inductors to filter power from molex computer PSU
7) replaced stock oscillator with vanguard TCXO 0.3 ppm

At the moment I don't have any other source to compare, but I can say no one of my previous CDP (onkyo and Sony) or budget DAC like the Beresford caiman, matched actual overall performance

I have to work to smooth out some harshness in voices, but sound stage, instrument definition and texture, dynamics, bass impact and control are simply amazing

The music is impactful, emotional, vivid, just a little more ... aggressive with voice on some recording
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Old 25th December 2011, 01:09 PM   #7
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So you use this as your dac rather than using an external dac? I have always wondered if this card has had modifications done only to deal with the coaxial section in order to go against any other transport out there (i.e. All these USB transports people claim are superior to sound cards or most anything else), servers, etc. etc.

Not to go off-topic and sorry to hear the TCXO part did not work for you.
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Old 1st January 2012, 08:50 AM   #8
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Yes, I use it as my main dac

I currently solved the issue about TCXO, it was just matter of uncorrect grounding causing oscillation

This card has 3 distinct power supplies, 3.3, 5 and 12V, each one with its own ground, plus the cabinet ground, so it is no easy to catch the correct ground for a given add on

Anyway now everything is fine and the result is simply amazing, never felt before such a solid instrument presence in my room
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Old 29th April 2012, 09:29 PM   #9
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Hi Robyone, Im interested in the mod you did: added wima FKP 3.3u to opamp bypass caps,
can you explain me how you did it and what are the benefits? thanx in advanced.
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