Marantz CD63 & CD67 mods list - Page 1039 - diyAudio
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Old 2nd July 2008, 11:09 AM   #10381
SimontY is offline SimontY  United Kingdom
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Quote:
Originally posted by RCruz
Not adding extra caps.... just moving them nearer to the opamps.

Maybe I do not need them because I already have the 220uFBG on the opamps...
I suspect they won't really make much difference, as there are local BGs and these would be close to those! You might want to investigate where else you could use the 470uF Black Gates. You could put them before the regulators (although they're fairly small for smoothing it'll sound good) or elsewhere, such as DAC, decoder, servo... preamp???

Simon
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Old 2nd July 2008, 11:50 AM   #10382
pzogal is offline pzogal  Europe
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Default a clock question

Hi, another question from me

Recently (monday ) I implemented Ray's clock (http://home.quicknet.nl/qn/prive/ra....s/CD_clock.pdf)
with one mod though. Instead of J310 I put a BF245C JFET inside. I suppose G & S are replacable but even though I soldered it according to datasheet (opposite pins to J310). It worked from the start, the result is more resolution in highs and there are much sharper ends to the notes in general, which gives impression of more pace & rythm. Bass is faster too. My Q is: does the pot setting matter ? Since I don't have scope at home, I set it so I get the same DC on the reference and oscillator input at the comparator. This gives me about 1100 ohm on the pot which is then comparable with R5 (1k). While measuring the comparator output, I get ca. 1,2 V DC , I thought it should be about 0.5 Vcc. Does it really matter ? CDP works with different pot settings & so far I couldnt hear a difference.

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Pawel
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Old 2nd July 2008, 11:55 AM   #10383
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1.2V is fine, iirc the max clock input V is 5V.

Brent
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Old 2nd July 2008, 01:34 PM   #10384
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Pawel, the pot is there to adjust the duty cycle. Without a scope I believe the best would be to adjust it to get the same dc voltage from both outputs (pin 7 & 8) with reference to GND. I think it should be close to 2.5Vdc.

Hope it help.

André
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Old 2nd July 2008, 01:49 PM   #10385
pzogal is offline pzogal  Europe
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Hi Andre,

I know, I am just curious if the % of the cycle matters in this case. Well, assuming 1.2V it is about 25% instead of 50%. And shouldn't be the duty cycle 50% having same DC on both + and - inputs ? I assume the comparator should theoretically output either +Vcc or 0V for Vin>Vref or Vin<Vref, thus setting Vref to DC component of Vin should give 50%. Anyway there is probably an error somewhere in my thinking, but hey, the thing works

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Pawel
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Old 2nd July 2008, 02:19 PM   #10386
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OK, I see now you did measure the output, I would still try to get both the same as the one is inverted. I don't think the meter will be that accurate at 16Mhz.

André
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Old 2nd July 2008, 02:23 PM   #10387
pzogal is offline pzogal  Europe
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Yeah, I think the same - most likely it's the DMM But the point is, it works!
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Old 2nd July 2008, 04:04 PM   #10388
6h5c is offline 6h5c  Netherlands
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Hello :-)

Good to hear the clock works o.k. It's a great little circuit. The key is not to measure at the output, but at the input side of the comparator....

Measure the DC offset at pin 2, and adjust the pot for the same offset at pin 3. That's all! It's best to do it without the comparator installed, or the clock connected to the player, as sometimes the player can go wild when you touch pin 2 with the DMM pin.

BTW, the duty-cycle doesn't matter much, because the clock signal is buffered by the DAC anyway, but hey, if you adjust it, you may as well do it right .

Regards,

Ray
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Old 2nd July 2008, 10:02 PM   #10389
RCruz is offline RCruz  Switzerland
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Quote:
Originally posted by rowemeister

The ones next to the opamps are fine, remove C805 C806 as they are not needed.

I'm sure you can find somewhere else for them

After reading Simon comments, I believe I will now place some +-15v spowers near the opamps.
These will be mounted on a veroboard with pins to fit R613 614 615 616, without output caps.
(This is good because I intend to re use the spowers on the future discrete outputs)

What benefits should I have by replacing the actual 220uFBG by 470uFBG on the LM4562 opamps ?

Are there any tradeoffs ?

Regards

Ricardo
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Old 3rd July 2008, 07:35 AM   #10390
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Sound wise it will be very very similar, the trade of is the fitment is a little tight. May as well leave the 220uF in.
What do you have on the DAC digital?

Brent
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