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UPGRADING THE CRYSTAL (X0) ON ESSENCE STX - Page 12

post #166 of 238
ordered clock today, and also 2x opa-earth
This will be fun.
post #167 of 238
Anyone else try this mod? I am doing the mod and have a question.

I ordered the same JZ-1 clock that GworldSpace used. I am wondering whether you can connect the 12v power supply and ground from the JZ-1 clock to the molex power connector of the STX?
post #168 of 238
Quote:
Originally Posted by awesom-o View Post
ordered clock today, and also 2x opa-earth
This will be fun.
The OPA-Earths make great I/V converters. You can use ANY Audio-GD unit for buffer but only the Earth and the Sun V2 for I/V.
The Moon's are not stable for the I/V position and will produce heavy distortion from oscilltion.
There are a few memebers running these cards with discrete opamps.
post #169 of 238
Quote:
Originally Posted by Salvador View Post
Anyone else try this mod? I am doing the mod and have a question.

I ordered the same JZ-1 clock that GworldSpace used. I am wondering whether you can connect the 12v power supply and ground from the JZ-1 clock to the molex power connector of the STX?
Great stuff! Your going to give it a go?
Yes, you should be able to tap the power supply at that point.
post #170 of 238
Quote:
Originally Posted by ROBSCIX View Post
Great stuff! Your going to give it a go?
Yes, you should be able to tap the power supply at that point.
It is already done actually. So power was tapped from the 12v of the molex connector of the STX.

I did not do the mod myself so I will be able to try it out tomorrow night. Hopefully nothing went wrong and everything is ok.

I will update you guys once I get it.

I also grabbed some OPA Earth and Sun so I can test those too once I get the card back.
post #171 of 238
The Earth is great for I/V and the Sun V2 is good for buffer but tastes vary.
Let me know how it sounds.
post #172 of 238
You're gonna love the improvement !

I've found LM4562 to be a good standard op amp to judge changes with both in the I/V and the buffer and as a good relative measure against different op amp set ups.

Well worth changing are these caps - see below - they imit the quality the I/V section can reproduce because they are in a negative feedback loop that limits the bandwidth through the I/V section. I think the DAC on this card might have a brickwall output filter because the sound can be quite aggressive at the very top end and apparently this might be due to pre-ringing caused by the DAC's filter. Changing the caps can help bring sweetness to the very high treble of cymbals and snares etc.

If you're using the RCA output then it's also worth changing the output coupling caps (in the left of the second picture). I've got Blackgate NX (bipolar) for these and they are much more revealing and transparent.





Cheers
post #173 of 238
That top picture is nice, the photographer has real talent
post #174 of 238
:-)
post #175 of 238
Thread Starter 
Its been a long time ago I posted in this thread. But it seams that things are going in right direction. THOPPA is made great progress in tweaking the STX. I will maybe also try the caps mode. Go on guys! )
post #176 of 238

Help!!

Alloa everyone

First of all, I'd like to thank the various people in this thread for providing info on this mod for the xonar essence. Reading this has inspired me to perform the same mod on my own card.

However, something seems to have gone horribly wrong, and I'd like to ask for help on how to fix things.

Basically, everything coming out of the card sounds like it is being dragged down by molasses! It's as if I applied movie special effects on it and have everything in slow motion.

Ok, here are the things I mucked around with:
1. Removed the coupling capacitors for analog output and replaced them with wire. (As recommended by germanium in another xonar essence post)
2. Replaced the 2 oscons in the power supply section with 1000uF Sanyo WGs.
3. Replaced the default crystal with a Vanguard 24.576MHz TCXO. Similar to what thoppa did, I connected the ground pin to the ground pin of a nearby IC, and connected crystal's Vdd to the pin adjacent to J15.


I'm not sure if the problem is because I replaced the oscons with a cap with higher uF (270 -> 1000), or if there's a problem with the particular XO unit I have. Part of the prob is that I don't have soldering skills to speak of (I relied on a repair tech for the mod), so I can't just swap things back, or listen to the results right away. If you guys can give me an idea on where to start, it'd be REALLY appreciated.

Cheers
post #177 of 238
Hi,

Your first post eh ? Welcome !

I had the exact same problem - your xo isn't clocking the signal correctly.

It could be you've connected it wrong, or it is faulty.

For me, it wasn't connected because I didn't solder it well enough. I initially thought I'd used a wrong earth so I changed the earth connection and it worked.

However, when having a look at the earth on a scope for noise, I realised that I had used a correct earth but just didn't flow the solder well enough.

So try again. I'm sure you'll be able to fix it if I did !

BTW, have you measured the output DC offset on the output without the coupling caps ? I imagine it's quite high (2 volts dc or more ?) but I assume that you are feeding the signal into gear that has input coupling caps ?

My card is finished. I'd say the XO made the biggest difference, replacing the ceramic feedback caps and using a linear PSU were tied for second. Replacing the output coupling caps comes a close third. Replacing the decoupling power caps came last. After all the changes, I rolled my fave op amps for a week or two and I settled on LME49720HA in the I/V and AD8620BR in the buffer.
post #178 of 238
D.C. offset should in fact be very low, 2millivolts or lower. This card has the lowest D.C. offset I've ever seen when D.C. coupled so that shouln't be a problem unless one of the I/V amp channels is faulty. I always measure D.C. offset before connecting to anything whenever I make a change. In the case of a faulty I/V amp yes you could see close to 2.5 volts if one of the 2 I/V amp channels is dead. 2 I/V amp channels for each output channel (left or right output). If one is dead then D.C. offset will not be cancelled in the buffer amp. When the I/V amps work correctly the D.C. offset is cancelled in the buffer amp because it goes into both the +input & - input of the buffer amp.
post #179 of 238
Hi,

Thanks for posting this. I wondered if the op amps were biased at all but obviously they are not if there is virtually no dc offset.

I have never bothered to measure - I'm not using any coupling caps in my head amp (and that has 8mV unconnected), so if I took out the coupling caps in the ST and something went wrong, I'd fry my cans. A pop, then a rattle, ...then wailing...hehe. Of course, not much chance of something going wrong now it's finished, but still....
post #180 of 238
It is definately most important to check the D.C. offset whenever you change anything as it will tell you if something is wrong even if you leave the caps in you can measure it at the input of the caps. I have never had a failure however that resulted in huge D.C. offset at the output.

That 8 millivolt is that at the output or input side of the head amp? If on the input side D.C. coupling the Essenses output would reduce that to less than 2 millivolts which would reduce the D.C. offset at the output as well of the head amp. if it is measured at the output of the headamp & it is a D.C. amp then the D.C. will go up or down by whatever the gain is of the amp. If the gain is less than 4X voltage gain then the D.C offset will go down & if greater than 4X it will go up by what ever factor the gain is abover 4X in your situation. Others will be different of coarse. if it is an A.C amp (no D.C. amplification capability) then the D.C. offset on the output of the amp will go down if connected to the Essense without the caps in place.
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