I can understand manufacturers leaving the XO's running but if done as you describe (and can discern a clear audible difference) then how did they meet there specifications? So I've been wondering what may have changed in there build from the first tested units?
New XO drivers, new FPGA firmware which distributes the unused clock to more cells, new crystals, new regulators? (just to name a few)
The lack of damping or limiting Rs on the XO may indeed result in higher peak current demands. Again something may have changed from their initial test units, where now it is a problem.
I have had bad experiences with ferrites in the decoupling network for XO's.
Looks like it might not be to hard to run separate regulators for each XO.
Good Luck, thanks
-Antonio
The sides are connected to ground, I think connecting either side is ok (they measured zero ohm across), not sure if it'd be better if both sides are connected.
They did not show a circuit equivalent. But I think it is a ferrite plus a cap to the ground.
My Transporter is heavily modded, not the stock SMPS, not the stock clocks, and a bunch of measures to lower electrical noise. My latest discovery is that by removing power to one clock, the sound is significantly better. It is so much more dynamic and engaging. It depends on how high the bar you set for the sonic quality you want. My bar is fairly high.
I'm sure 99% of the manufacturers leave unused clocks running but they don't see the sonic problem because their bars are not set that high.
After this discovery, I disable two unused XOs inside my TacT 2.2xp digital preamp's output cards. I heard the same sonic improvement. So it is a confirmed issue leaving unused clocks running.
I know some people avoid magnetic components inside audio gear like plague. Someone just told me to avoid ferrite, while it may attenuate the noise on Vcc, the magnetic field it generates will muck up the sound. This person has even a high bar than I do when it comes to audio. I've seen and heard R-core xformer mucking up the sound if placed 5-6" away from a DAC chip.
Regulators are useless in isolating high freq noise in the MHz range.
Regulator could be an opamp for a clock supply, but if fast enough to regulate fixed voltage to 10MHz of course will transfer pulse load to the powersupply anyway, so you need high impedance there one way or another. Try a copper shield around the beads if you think they are transmitters... Too much is never enough?
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That is an urban legend. Ferite beads have only positive effects. People that say that they "mud the sound" probably got used with harmonics and distortions (in form of high-frequency harmonics) and whenthey hear a clean sound they say it is "mudded".
Regulators do NOTHING for a digital chip, only capacitors (close to terminals) can provide the needed fast variable load current.
Thanks for the report. I looked in my inventory and I never did get any of these (although I remember seeing the images and weird SMD lands).
By the way, do the in/out terminals measure as low resistance? That would answer my question as to whether they're caps or inductors. Obviously, an inductor would have low or zero ohms, whereas a capacitor would measure as an open circuit (unless charged, in which case the reading would constantly change). Forgive me if I'm the only one confused by these parts, but an EMI filter that is measured in uF just seems odd, especially without any other impedance specifications.
EDIT: Are you making your own PCB for these mods? It seems like you could end up with a mess of white wires if you try to mod the Transporter in situ.
Kuro, SoNic_real_one
Sorry for my comments they appear to have just caused more tangents. Please allow me to try to explain:
I have seen the effects of multiple clocks, it was developmental video type assembly with 2 XO's of which only one was to be installed. By accident the 2nd was installed and operating (driving an unused FPGA input only) and since these were nearly identical XO's the resulting video had a low beat frequency (10Hz ish) that was very visible. However there are ways to mitigate these effects. Does your transporter have another XO on the assembly? For fun you could install the same XO's on each and then you would really hear any interacting effects.
As for the ferrites I did not mean to associate my bad experience to any audio quality. I unfortunately suffered through an oscillator that would not start (motor boated) when the supply was decoupled with a ferrite bead. Certainly there were numerous circumstances which added up (the biggest being my carelessly using a ferrite bead) including power supply turn on rate, temperature and the ferrite / capacitor filter impedance near the oscillator start frequency. Yes these effects could have been easily overcome with a parellel R or an RC snubber to ground but my point was that one needs to look at the driving impedance when loaded by an oscillator climbing its Q.
Lastly for the regulators I wasnt proposing to use them to actively try and level the bias, but rather to use there low frequency characteristics to smoothen the fast current pulses reflected back to the common raw supply.
As a minimum they allow for substantially larger series resistors on their input to assist in decoupling the two XO supply voltages.
I hope that some of my mistakes from years gone by are of consolation and help to you
Thanks
-Antonio
I finally solved the problem by using feed through caps from AVX. The cap is designed to work like an EMI filter to provide noise attenuation from 1MHz to over 1GHz. At 1MHz, the attenuation is 60db. And the max attenuation is around 80db depending on the value of the cap. The values of the caps I used are 10uF and 1uF (for the 2 different freq clocks).
I soldered a SMD feed throught cap on the underside of each XO and viola, superb sound even with 2 clocks running at the same time! In fact, the sound is even better than just having 1 clock without the feed thru' cap.
I soldered a SMD feed throught cap on the underside of each XO and viola, superb sound even with 2 clocks running at the same time! In fact, the sound is even better than just having 1 clock without the feed thru' cap.
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