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 Post subject: Re: Very Nice Transport
PostPosted: Thu Mar 04, 2010 10:57 pm 
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Hen

Joined: Thu Feb 11, 2010 3:31 am
Posts: 3
Maybe I will still go with the picogates.. Now I just need to find a good schematic.. :)


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 Post subject: Re: Very Nice Transport
PostPosted: Sun Mar 07, 2010 7:47 am 
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Hen

Joined: Thu Feb 11, 2010 3:31 am
Posts: 3
TentXO outputs square wave, so I need just the flip flop for reclocking and feed the player and flip flop with the TentXO? Or do I need those buffers? TentXO "can drive 3 HCmos gates". :blink:

Something like this:
Image

:confused: What are right values for those 300R & 100R?


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 Post subject: Re: Very Nice Transport
PostPosted: Sun Mar 14, 2010 7:08 pm 
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Pig
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Joined: Mon Dec 13, 2004 2:32 pm
Posts: 1325
Dan,

Sorry for late reply, but I guess it’s still better late than never.

As I said, initial impression was very positive so I went through several efforts to improve on it, but they were relatively unsuccessful. Taking into account that originally measured performance was extremely good too, this might not be that surprising, of course. Anyway, neither mechanical nor electrical tweaks / additions brought any really meaningful sonic improvements. Mechanically, the transport is relatively insensitive (!), and applying even some previously known tweaks was about inaudible. I also tried external Colpitts oscillator, driving S/PDIF reclocker directly, and I tried adding several line drivers as well (the picture shows the transconductance MAX436 (now obsolete) based one), but there is an overall impression of continuous risk to screw up something. So, beware, unless you really have your favorite circuits for these purposes, this undertake may be frustrating.

I don’t know if it worth swapping 7808 based regulator you have by something fancier, but the bottom line is if you already own and are really willing to enjoy this transport, it may be the best just to sit back and enjoy it.

There are two practical issues I experienced, none of them being any really serious though... The first, the transport is a bit noisy, especially since I keep it “open mounted”. And second, it doesn’t read erroneous discs very well. At least this is my experience with my own sample.

As for you offer, I’m normally reluctant to do the things that way, but thanks anyhow, I’ll keep this on mind in case it is needed.


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 Post subject: Re: Very Nice Transport
PostPosted: Mon Mar 15, 2010 12:50 pm 
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Sheep

Joined: Mon Oct 08, 2007 1:37 pm
Posts: 88
Location: Ontario, Canada
Thanks for the response Pedja. I've been meaning to look further into the reclocking but I have two teenagers that have been keeping me busy lately.

Regards,
Dan :)


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 Post subject: Re: Very Nice Transport
PostPosted: Tue Mar 16, 2010 11:48 am 
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Goat

Joined: Sat Mar 04, 2006 5:26 pm
Posts: 576
Location: Nova Scotia
Ekke wrote:
TentXO outputs square wave, so I need just the flip flop for reclocking and feed the player and flip flop with the TentXO? Or do I need those buffers? TentXO "can drive 3 HCmos gates". :blink:

Something like this:
Image

:confused: What are right values for those 300R & 100R?

Assuming you're not compensating the transformer with the same circuit, the impedance of the capacitors is insignificant and R1 is 300 ohms and R2 is 100 ohms as shown, you want 75 = (R1+Rgate)||R2. Rgate is the output resistance of the gate. Select R1 and R2 for ~2Vpp into the transformer. I'd start with 150 ohms for both, then parallel something with R2 to compensate for Rgate.

Also, borrow a 2 channel scope from someone and measure the phase relationship of the clock and the CDP digital output. If the CDP's digital output changes on the rising edge of the clock, you'll need to put an inverter in front of the 7474.


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 Post subject: Re: Very Nice Transport
PostPosted: Fri Mar 19, 2010 5:50 pm 
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Pig
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Joined: Mon Dec 13, 2004 2:32 pm
Posts: 1325
Dan, just some clarifications... I don’t know anything about your experience, but in my experience, the transport "as is" has relatively big soundstage, but somewhat... "simplified". It lacks really precise positioning in all three dimensions (pin pointing), and places a singer a bit forward, and all the others a bit back instead. But tonally it is full, and very nice and correct, so piano is healthy with no kling-klang effects. Adding reclocker you may be able to get more precise soundstage, and also to bring some top end sparkles... but at the risk of losing just said good sides.

And... let's try Pedro's latest phpBB button. (EDIT: Yeah, it works, definitely.)




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