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Old 25th July 2004, 08:00 PM   #11
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The Audiocom seems to pander to 'audiophile' pretensions by littering BG's around as if they are some magic panacea.

Both clocks are still sensitive to external PSU's though.

Andy. [/B][/QUOTE]
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I tend to agree; the Audiocom uses basic regulators as well.

Not only is the PS important; the type of XO is importajnt. The Tent XO and Valpey-Fisher VF XO feed less back into the PS. Chip type XOs seem poor. In this sense, a separate transformer is desirable. I have actually used a preregultor (78xx) to stop this feedthru' with some success.

It is not the clock, but the clock.digital p[rocessor and PS as a system that matters and I have found it useful to carry out on board measurements of waveform and PS noise.

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Old 25th July 2004, 09:03 PM   #12
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Post Clock Powersupply

Quote:
Originally posted by Hans L
I would be very surprised if you find someone that used both. I have installed a LC Audio clock upgrade once and I was quite pleased with the results, which also included modifications to the power supply (which is probably the first place to start) and to the analog output section. I'm definately not an EE but had help from internet and friends.

I can't imagine why one ultra low jitter clock with could be audibly better or worse than similar clock. Evaluate them based on wether they have a decent seperate power supply offering. Other than that it's strictly based on the price difference.
Hi Hans,
I did not mean that powersupply is not important. My clock has on board low noise regulators and chokes and caps forming a PI-filter together with the main filter caps of the player's digital supply.
I also have tested various low noise regulators. Especially interesting was the following observation on two types of low noise regulators. Both regulators had equal noise specs. One sounded totally uninvolving and uninteresting the other just right. How come? Also tried with and without preregulation in my Philips CD931 and the Sony SCD-1. In both cases sound was better without preregulation.
You can download the schematic here:
http://www.diyaudio.com/forums/showt...928#post199928

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Old 25th July 2004, 09:25 PM   #13
Hans L is offline Hans L  Netherlands
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Default Re: Clock Powersupply

Quote:
Originally posted by Elso Kwak
Also tried with and without preregulation in my Philips CD931 and the Sony SCD-1. In both cases sound was better without preregulation.
You can download the schematic here:
http://www.diyaudio.com/forums/showt...928#post199928

Hi Elso,

thanks for the link. I wasn't aware you were designing this stuff for fun
Any idea why a PS without preregulation sounds better? Or has this already been discussed elsewhere on the forum?
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Old 25th July 2004, 09:48 PM   #14
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Cool Re: Re: Clock Powersupply

Quote:
Originally posted by Hans L

Any idea why a PS without preregulation sounds better? Or has this already been discussed elsewhere on the forum?
Hi Hans.
My theory is that the regulators interact with each other. See also this thread on an other forum:
http://db.audioasylum.com/cgi/m.mpl?...lator&session=

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Old 25th July 2004, 09:58 PM   #15
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Quote:
Originally posted by fmak
The Audiocom seems to pander to 'audiophile' pretensions by littering BG's around as if they are some magic panacea.

Both clocks are still sensitive to external PSU's though.

Andy.
Chip type XOs seem poor. In this sense, a separate transformer is desirable. I have actually used a preregultor (78xx) to stop this feedthru' with some success.
[/B][/QUOTE]
The Tent clock is a chip type oscillator in a metalcan enclosure:
http://www.diyaudio.com/forums/showt...1962#post11962
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Old 25th July 2004, 10:10 PM   #16
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Quote:
Originally posted by Elso Kwak
the Tent clock is a chip type oscillator in a metalcan enclosure:
http://www.diyaudio.com/forums/showt...1962#post11962
Quote:
Originally posted by fmak
Not only is the PS important; the type of XO is important. The Tent XO and Valpey-Fisher VF XO feed less back into the PS. Chip type XOs seem poor. In this sense, a separate transformer is desirable. I have actually used a preregultor (78xx) to stop this feedthru' with some success.

If I understand Fmak correctly the mentioned canned XO types feed less through but chip types in general are poor in that aspect.

No need for referring by incomplete quoting to a "competiting" product that happens to be a ( hint hint, wink wink ) canned type XO, Elso. People might start thinking that your clock is better
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Old 26th July 2004, 07:46 AM   #17
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The Tent clock is a chip type oscillator in a metalcan enclosure:
http://www.diyaudio.com/forums/showt...1962#post11962 [/B][/QUOTE]
------------------------------------------------------------------------------------
You know what I mean and I did specify the 2 can types that are better.
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Old 26th July 2004, 09:38 AM   #18
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I have used LC Audio XO2 clock in 4 players, all 16.9MHz, with great success. However, I replaced C1 with 3 X 2200uF / 35V FK Black Gates type, and I removed C10 + C11 + C5 and C6 and replaced with 0.1uF / 50V Nx Black Gates. This by itself was more important then clock installation in its original form.

I tried borrowing the current for the clock from existing power supply rails within the CD players, and was disappointed. I tried analogue rails, as well as digital. Installing separate transformer with fast switching / soft recovery diodes was a huge improvement. Also, I noticed that higher voltages worked better than lower ones. To me, it appeared that power supply quality had greater impact on sound than clock design in itself.

0.1uF / 50V Nx type Black Gate is an absolute champion in lowering the noise level. It does not like any by-pass capacitors, it likes to work alone! I have used it a lot in digital sections of the CD players, together with ferrite beads, to great success.

Cheers
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Old 26th July 2004, 09:42 AM   #19
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Quote:
Originally posted by Elso Kwak

Chip type XOs seem poor. In this sense, a separate transformer is desirable. I have actually used a preregultor (78xx) to stop this feedthru' with some success.


Hi

Most chip types are poor, as are some (commercially available) discretely built clocks.

You can easilly see PS dependancy if you can measure cycle to 100k cycle jitter.

As long as you cannot measure this, all you can do is speculate.

cheers
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Old 26th July 2004, 10:28 AM   #20
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Default Re: Audiocom clock vs. LC Audio clock

Konnichiwa,

Quote:
Originally posted by KevinLee
The Audiocom clock is a version 1.1 and the LC Audio is a XO2.

Has anyone tried both of these clocks?

Does anyone have any preferances and why?
I have tried during mods many types of clocks, most made the sound worse, not better, even when implemented carefully.

The reasons are manifold and I will only list a few common ones, like the often unavoidable introduction of added ground/noise current loops, a mismatch between clock output voltage and players logic level (many current players have 3.3V core logic supplies and levels, most if not all commercial clocks are 5V logic based) and overly long not impedance matched output wiring (losely twisted pairs) distorting the waveshape.

So, in many ways a clock replacement has to be "designed in" into the Player, rather than being a "bolt on add in" if it is supposed to work well. The reason I prefer the Tent Clock is that it is possible to implement this with a VERY TIGHT layout due to small size.

The clock can be placed only millimeters from where it's signal is needed, the supply filtering can be done using LC circuitry and you adapt the voltages with resistors as the actual output wiring. Just make sure you don't introduce ground bounce and that you tap off the 5V supply from somewhere in the player close by but low noise....

Sayonara
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