Marantz CD63 & CD67 mods list

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#1,001
i was going to do some test to see the drive capabilities of the dac
just a bit of info for passive filter

so far
removed output caps, muting, headphone, DAMH🙂D ), improved various caps, .1uf bypass caps to get .1mV noise on any rail, iec and rerun earths, opamps-2134's

very much improved for such cheap mods

oh yes forgot to fit opamps in sockets, still got resonable signal out.
yes restricted on frequency
looks promising for the passive filter to buffer😀

allan
 
#1,005
ash_dac said:



haha 😎

You removed the hdam ?

What was the voltage of the signal you got ?
Click to expand...


hdam yes (bypassed all)
suggestion by a fair few on here and elsewhere that with a better opamp, the hdam doesn't help.
i tend to agree with them😀

on schematic voltage into opamp 1.4v

without opamp, it goes though the feedback caps/resistor circuit🙄
as i said restricted frequency.
will have to measure it.

thinking about making small pcb to plug in opamp sockets😀

at lest that way i don't have to keep removing pcb to test ideas.

allan
 
#1,006
ash_dac said:
Hi,

Does anyone know anything about pwm signals, and pdm signals ?
A pwm signal comes out the Marantz dac....
Is this pwm signal at 44.1khz or is it higher ?
Does the 1st stage after the dac just generate a voltage from the difference in the +/- left/right output ? (still 0/1 pulse)
..and the low pass filter turns the pulse into audio ?
Click to expand...

Hi ash_dac,

I put my scope on the DAC and measured between 0.5 and 1uS for a period, so my guess is the output frequency is pretty high, 32*Fs or 1.411MHz.

The first stage does some passive filtering and the first opamp summs and amplifies both outputs to a single ended signal. At this point it's already more or less analog, with lots of HF residue. Then a second opamp stage filters a bit more. If you take out the opamps, like Allan did, you have reasonable music, with lots of noise.
The HDAM circuit only acts as a buffer, so if you bypass it the amplitude of the output signal stays the same.

Regards,

Ray.
 
#1,008
6h5c said:


Hi ash_dac,

I put my scope on the DAC and measured between 0.5 and 1uS for a period, so my guess is the output frequency is pretty high, 32*Fs or 1.411MHz.

The first stage does some passive filtering and the first opamp summs and amplifies both outputs to a single ended signal. At this point it's already more or less analog, with lots of HF residue. Then a second opamp stage filters a bit more. If you take out the opamps, like Allan did, you have reasonable music, with lots of noise.
The HDAM circuit only acts as a buffer, so if you bypass it the amplitude of the output signal stays the same.

Regards,

Ray.
Click to expand...

no opamps was a mistake, just forgot to put them in🙄
but gave me better view of dac output hmmmm voltage
used to current out where you need IV converter

not really reasonable music maybe not as good as MP3:clown:

Hmmm converts to single ended
I have balanced input capability on my preamp.
why this cdpayer is good for experiments

allan
 
#1,011
awpagan said:
just changed C605/606 from 1000pF to 470pF and R611/612/605/606 from 10k to 12k1

listeninig to Nora Jones before and after
much much better balanced sound highs to lows
recommended

Ray's filter suggestions😀
Click to expand...

Hey, good to hear more positive results. Haven't got the 12k1 in yet, waiting for parts....

no opamps was a mistake, just forgot to put them in 🙄
Click to expand...

I know, it happens to me also from time to time :clown:

Ray.
 
#1,014
Hope this quote thing works (haven't posted much yet)....

quote:
Originally posted by philpoole
I've heard mixed comments on biasing opamps into class A. Some say that it shouldn't make any difference either because they're pretty much in class A anyway due to the low levels involved (we're not swinging between power rails here), or that the crossover distortion is minimised due to the feedback involved.
Likewise, others seem to swear by it.

Definitely one to investigate.

Cheers,
Phil


Well, maybe some say it SHOULDN'T make a difference but all the reports I have read from people who have tried it have been very positive!!!!
OP amp outputs are seldom in class A even if they are used at low levels and RELY on high open loop gain and feedback to LOWER not MINIMISE crossover distortion.

Applying a fixed drain (source?) current to force the NPN output transistors into Class A does not minimise crossover distortion but eliminates it completely!!
Click to expand...

Poynton, I agree it will make a difference, when forced into class A there will be no crossover distortion. I was just suggesting, with so much feedback the crossover distortion (in theory) should be negligible (BTW I thought lower and minimise meant the same thing, sorry if I'm misusing them) - which is why SOME are not so convinced. I actually believe it should help.
Anyway, as I said, it is worth trying.

Thinking about all this feedback really does make me think that Ray has the right idea with his opinion that a zero feedback output stage (be it valve or transistor based) is the way to go.

In the meantime, I will probably be investigating biasing. A simple FET and a resistor should be enough per current source, can't remember the formula off the top of my head, but I recall it forms a simple 2 pin current source. Not the best, but very simple.

avr300 I've had the Kwak Clock 7 in my 63 for about a year now, and I could never go back. These CDPs sound great when reclocked (like most others no doubt).
 
#1,017
Hey im back, and will probably start my modding asap, with the removal and bypassing of the output caps, clipping of the muting transistors, then the installation of the audiocom ebay package (kit 1: superclock 2, 5V super reg, 12V super reg, -12V super reg).

Ive decided that £1000 into my student overdraft isn't enough, and want to go further into it 😀

I just wanted a little help with what tools, and cables il need to do the mods.

poynton said:



Hi Adfinni,

I bought a load of these PSUs of EBAY. They fit just nicely behind the display panel.

These are as basic as you need :- transformer, rectifier (yes-I know it's a cheap bridge!!), smoothing caps and regulator.
( I have to make a slight mod as these are set to 6v - I will be setting to 9v then using a super-reg to +5v )

Layout is not critical so perf-board will do, if you build one youself.

Maplin also sell a small board for an adjustable psu ( part no. VE58N )- just connect a small transformer ( eg Maplin part WB01B ) and set the volts to +5v.

Andy
Click to expand...

poynton advised me to get the VE58N, and WB01B from maplins, to use as a PSU for the superclock. Are those those the only two things i need for the seperate PSU, and what sort of wiring will i need to complete the mod? (Sos im a noob, and don't want to screw it up)

Thanks
 
#1,018
adfinni said:
Hey im back, and will probably start my modding asap, with the removal and bypassing of the output caps, clipping of the muting transistors, then the installation of the audiocom ebay package (kit 1: superclock 2, 5V super reg, 12V super reg, -12V super reg).

Ive decided that £1000 into my student overdraft isn't enough, and want to go further into it 😀

I just wanted a little help with what tools, and cables il need to do the mods.



poynton advised me to get the VE58N, and WB01B from maplins, to use as a PSU for the superclock. Are those those the only two things i need for the seperate PSU, and what sort of wiring will i need to complete the mod? (Sos im a noob, and don't want to screw it up)

Thanks
Click to expand...

Hi is that the TENZING mod?
 
#1,019
Help..!

After my last mod i have strong noise on the output of my cd-67 if the volume of the amp is turned up fully and CD-Player is in stop or pause - which wasn't before (dead quiet!):bawling:

OK, what i did was the following:

-replaced all diodes (D801..804, DN 01..04, D811..12) with
Schottky and HFA08TB60;
-replaced C801/802, C811/812 with 0,1uF BG NX 50V
-removed C659/660
-removed R657/658 (jumper)
-replaced R659/660 with 100R (caddock)
-removed muting transistors (QN05-08)

I'm a bit in panic now, may i have damaged something..!?!

May this be related to the muting-transistors?
Sound is OK though...

Rest of the Output-stage is still untouched...

yours,
Mickie
 
#1,020
ash_dac said:


Hi is that the TENZING mod?
Click to expand...

Nah, the tenzig mod is a total overhaul of the player that costs ~£1000, which is far too much. You can spend a couple of hundred on electrical and mechanical modifications to the player to make it sound great. That's what im doing along with most the others in this thread.

With regard to my £1000 comment, that's just how far into my student overdraft i am, and want to spend more more more !!!
 
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