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Old 6th October 2002, 07:06 AM   #21
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Lightbulb Corrections

Quote:
Originally posted by Peter Daniel


>The CLOCK output is directly connected to pin 26 of SAA7210 (digital signal processor) <

Is that correct? Or is the output of a clock connects to pin 19 of SAA7210?

Hi Peter,
Sorry for confusing you. (Too much alcohol) . Yes the clock is connected to pin 19 of the SAA7210.
Regarding the Russian opamp-roulette; I gave up this game a long time ago. OPA627 was one of the winners.
It will be intersting if you corroborate my findings regarding the soundquality of the TDA1541AS1 vs. the AD1865N-K, or not.
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Old 6th October 2002, 09:57 PM   #22
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Default TDA1541

I am considering the use of two TDA1541, opposite phase, feeding a Sowter 9055 transformer (1:18,7 turn ratio). Two 50 ohm resistors are used for I/V conversion and there is no active analog stage at all. Phase opposition is obtained with two XOR gates before the DATA input. Opinions welcome.
Marco
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Old 7th October 2002, 04:30 PM   #23
dice45 is offline dice45  Germany
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Marco,
I liked your idea so i just asked my friend MHuber who has the Sowter9055 in use in his DAC. He set me straight this won't work properly without an active stage.
You have those 50Ohms as source impedance seen by the Xfrmr. Ratio is 18.7 so output impedance is 50R*18.7^2=17k5 .

17k5 driving 47k preamp input impedance. Not a good idea. Manfred used a tube output stage with a 4:1 stepdown output transformer to arrive at about 3k output impedance. I can tell from own experience that his CDP/DAC is not the best but the most musical digital i ever heard; i will build something very similar to that, using a CDpro2 drive.
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Old 7th October 2002, 04:38 PM   #24
dice45 is offline dice45  Germany
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Question Can CDpro2 drive be synchonized by external clock signal?

All,

urgent CDpro2 question: is it possible (and if yes, how?) to disconnect the connection between internal clock and drive on the onboard PCB of the CDpro2 module and is it possible then to synchronize the CD drive to an external clock signal, e.g. coming from the master clock oscillator sitting right beneath the DAC?
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Old 7th October 2002, 05:39 PM   #25
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Here is the info from Product Specification notes concerning VAU1254/11. SAA7324 decoder is on transport's PCB.
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Old 7th October 2002, 05:43 PM   #26
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There is also optional output (16Mhz), but the socket is not soldered to the board. That's more or less the info I got, but I can't answer your question for sure, Bernhard. Digital is something I'm still learning. But I would be also interested if this can be done.
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Old 8th October 2002, 02:35 PM   #27
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Peter and all,

the ThomasMayer/ManfedHuber DAC/CDP strictly avoids any SPDIF transmission between drive and DAC: 4 separate digital lines between DAC and drive; the master oscillator sits almost piggyback in the DAC and everything remote is soncronized to the master oscillator's clock.

I also am just learning digital, but from the subjective, listening side as well as from the conceptional, design side, methinks this architecture is one of the few possible stairways to heaven. Synchronizing the (remote) drive by the DAC's master clock is required to go that stairway.

I would bet that Jocko seconds this. Jocko?

Guess i will have to ask Mr Thevissen how to do this.
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Old 8th October 2002, 03:05 PM   #28
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Bernhard,

I am working on this: clock in the DAC and then feed it back to the transport. This with an old philips player and two TDA1541 in non-os. But it should be possible to use for other setups.

As for the clock of the pro. Check the datasheet of the decoder chip. Probably it can be fed with a TTL clock. The old 7210 in my player can :->.

I am thinking of using an asynchronious FIFO register to do the trick. Also using one programmable logic chip (GAL) and some normal logic.

Already using the GAL and some logic to "split" the I2S signal into left and right (so one TDA1541 is left and the other is right channel, output can be made differential).

Anyway, if all is working, ill post the schematic, etc. I am now working on a PCB for the logic and DACs and i am about to order the components.

Greetings,

Guido
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Old 8th October 2002, 07:04 PM   #29
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Hello Guido!
happy you join this discussion.

I will ask Mr Thevissen, i have established phone contact with him already, just am careful not to overload him with QQ as i have not yet ordered. My funds are absorbed by 2 tonearms and an open baffle speaker at the moment.

He can answer my Q and tell me which oscillator freqency the drive uses and if the 11.28MHz clock needed for Manfred's DAC has to be mulitplied by 3/2 (glue logic + PLL) to arrive at 16.92MHz or not.

I guess i have Tent clocks for both frequencies, one of them i will definitely use. Thomas and Manfred consider this clock as A+++.
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Old 11th October 2002, 02:53 PM   #30
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Another useful link for anybody interested in NOS-DAC:
http://www.geocities.com/yury_g/dac.htm
Seems like the guy is really into coupling transformers.
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