Marantz CD63 & CD67 mods list - Page 490 - diyAudio
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Old 30th November 2006, 07:50 PM   #4891
6h5c is offline 6h5c  Netherlands
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And here's the schematic. The filter part values are for the SA8400, but it can be used with the original 63/67 FET/transistor stage. T1, T5 and T6 can be transistors or FETs (2SK170), or a mixed version can be made. Be sure to read a darlington for T1 (BC517) as I was too lazy to look one up . All will be sorted in the final version .

Ray
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Old 30th November 2006, 08:05 PM   #4892
avr300 is offline avr300  Denmark
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Nice. Will you be making PCB's?

You got a typo. C5 + C6, listed as uH.
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Old 30th November 2006, 08:20 PM   #4893
Glenn2 is offline Glenn2  United Kingdom
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Nice work Ray!

Separate regs for each channel can't be bad either.
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Old 30th November 2006, 09:59 PM   #4894
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Quote:
Originally posted by AndrewT
Hi Rowe,
why did you choose a T attenuator?

It gives a higher source impedance seen by the amp.

A plain L attenuator using 1k & 270r will give Zout=213r

Will the cdp like feeding a near 1k load?

Or fit it inside the RCA plug that goes into the amp.
Using lower values (270ohm) loaded the cdp output. The mV out before the resistor was being dropped which I did'nt like.

Some people beleive very firmly in attenuating the cd output.

http://www.russandrews.com/category....t_id=PINTEANAL

click on 'How do I cure that hard ‘CD’ sound?' (on the right)

and then click 'For more detailed information click here'

Brent
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Old 30th November 2006, 10:51 PM   #4895
SimontY is offline SimontY  United Kingdom
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Quote:
Originally posted by 6h5c
Why do you need a preamp anyway (unless you are into vinyl of course)? A rotary switch and a volume pot is all it takes. All sources like the TV, CD-player and DVD player are about the same volume level.

Regards,

Ray
Hi Ray,

Do you like that limp, lifeless sound? I prefer the sound with a preamp. Gutsy, with bass. I lived a while with the CDP straight into the power amp and it was not good enough.

IMHO

Simon
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Old 1st December 2006, 04:50 AM   #4896
Luke is offline Luke  New Zealand
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Default any good cdp trouble shooters out there?

Hi Guys

Ive got issues, any one got some ideas.
I posted here.
http://www.diyaudio.com/forums/showt...87#post1067287

Is a skipping cd player just a faulty laser? Im sure it was ok before I did my mods and everything hs been checked again. It seems to go fine somedays and bad others.

help much appreciated. Want to sort this play out so I can get onto finishing my cd67se:-)
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Old 1st December 2006, 05:12 AM   #4897
Will is offline Will  Malaysia
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Quote:
Originally posted by SimontY


Hi Ray,

Do you like that limp, lifeless sound? I prefer the sound with a preamp. Gutsy, with bass. I lived a while with the CDP straight into the power amp and it was not good enough.

IMHO

Simon

Hi Simon,
Have you tried a TVC before ? It'll change your mind about active preamps forever....

cheers..
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Old 1st December 2006, 07:28 AM   #4898
AndrewT is online now AndrewT  Scotland
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Hi Rowe,
you can attenuate your CDP if that gives improved sound. I have no problem with that. Or even if it improves operation (matched signal levels).

I asked two questions.

Why "T" when it increases the source resistance seen by the receiver?

Can CDP drive a near 1k load?

Are you sure you have the correct/best attenuator here?

Why on earth refer me to Russ Andrews' site selling attenuators for £90 a pair, when you can make one with two resistors costing £0.015 and fit them inside an existing RCA plug?
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Old 1st December 2006, 07:34 AM   #4899
AndrewT is online now AndrewT  Scotland
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Quote:
Originally posted by SimontY
I prefer the sound with a preamp. Gutsy, with bass. I lived a while with the CDP straight into the power amp and it was not good enough.
Simon, this sounds more like a better matched set of input/output impedances rather than better with a preamp.

Passive attenuator is difficult to get performing well if the source and receive impedances are dancing all over as you adjust volume. But, it is possible with certain combinations.

Adding buffers before and/or after the volume help tremendously at correcting the required impedances.

The pre-amp if designed correctly is basically a buffered volume control and a switch. It's the correction provided by the buffer that gets rid of the problem impedance that sounds better. Not the pre-amp per se.

Will,
what's a TVC?
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Old 1st December 2006, 07:41 AM   #4900
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Quote:
Originally posted by AndrewT
Hi Rowe,
you can attenuate your CDP if that gives improved sound. I have no problem with that. Or even if it improves operation (matched signal levels).

I asked two questions.

Why "T" when it increases the source resistance seen by the receiver?

Can CDP drive a near 1k load?

Are you sure you have the correct/best attenuator here?

Why on earth refer me to Russ Andrews' site selling attenuators for £90 a pair, when you can make one with two resistors costing £0.015 and fit them inside an existing RCA plug?
I went with the 'T' circuit after plenty of research, there is conflicting ideas on which is best but there seemed to be more favour towards the 'T' over the 'L'. Some amp inputs did not like the resistor to gnd.

I sent the link to Russ A so you and people could see the reason for doing this. NOT to buy one. And why can't he make one with cheap plugs as he charges a small amount to buy an interconnect with the attenuation option fitted!

Maybe 1K could be a little large a value, this is for me to experiment with.

Brent
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