Marantz CD63 & CD67 mods list

[awpagan]

Originally posted by poynton
For those unfamiliar with the Zap Filter...


http://www.lcaudio.com/index.php?page=6




Andy

oops

sorry should have posted a link to it

thanks andy


allan

[6h5c]

Originally posted by awpagan
Almost to 6000
It's all you fault Ray,
well almost, plus a few others

Wow, 6000 posts and counting...ok, I plea guilty...I admit fueling the irresistable urge of many to customize their equipment in search of the ultimate audio-experience .

Originally posted by poynton
==========================================

Hello to all contributors to this great thread.

It has been a credit to all for the lack of backbiting etc. and the very good natured responses even when some of the questions have been from inexperienced DIYers.

See you at the UK DIYAudio Fest?

Andy

Couldn't agree more, Andy! Thanks to all that contribute(d) for the good atmosphere here.

Here's the latest thing I've done to my SA8400 .

Interesting discussion about the LM4562 BTW, it's not the ultimate opamp for me either. Indeed it gives a lot of extra detail and information to the music, but in the long run I find it too sterile and clean. I like my AD8610/AD8510 combo better, it involves me more in the music. Guess it must be the AD-sound.

Regards,

Ray

[poynton]

Originally posted by awpagan



oops

sorry should have posted a link to it

thanks andy


allan

Hi Allan,

Been over the bridge today ???


Andy

[awpagan]

Originally posted by poynton


Hi Allan,

Been over the bridge today ???


Andy

News does travel fast.
15th from the right, row 237, i waved......



unfortuately the novelty of the bridge has pasted some time ago.
frequent user

there is still a law in place to herd sheep across the bridge between certain hours
some uni students tried years ago,,,,,,,,,,,

maybe it's just been used



allan

[poynton]

Originally posted by awpagan



News does travel fast.
15th from the right, row 237, i waved......

OK. I just looked again..

I've never seen a didjeridoo played like that before !!!!

Andy

[awpagan]

Originally posted by poynton


OK. I just looked again..

I've never seen a didjeridoo played like that before !!!!

Andy

Pied Piper aussie style????
didjeridoo and sheep???

allan

[Malefoda]

Originally posted by martin clark
Right here

Don't worry that shuld work OK.

The 17.6v figure is the lowest that is guaranteed to work with tolerances of parts - but not the raw PSU - taken into account:

7812 puts out 12.0v nominal, raised from ground by the LED - 1.95v actual, say 2V = 14.0v;
7812 dropout needs to be 2.2-2.5v min at low currents;
Gyrator portion drops 0.65v+ small amount through bias network to drive BC547. How much? well it's the output current - say 20mA - divided by Hfe, say 300 (pessimistic for a BC547C at 20mA). That's 67uA, or 0.67V across the 10K biasing resistor.

So we need (14.0+2.5+1.3v) input, 17.8V, to guarantee it will work. In fact, because the BC54x will have a Hfe of c.400 at these currents, most LM7812s are actually about 11.9v to avoid exceeding their rated voltage (and fwill work with 2.3v overhead at 10mA output) and the LED voltage reduces at -2mV/degreeC, 17.6 will work - always, but that's why it's given as 'minimum minimum'; it gives no allowance for variation in the output of the raw PSU.

If you're worried that your implentation is a bit marginal, then monitor the output from the 7812. It should be constant to two decimal places at (around 13.9v, +/- a little bit). If you see it wandering by 10mV or more over a few minutes then it has insufficient voltage input, and the fix is either more raw input, or reduce R1 (say to 5K ) and try again.

Well, it seems there's also an "average minimum"...
My main dances from 225.00 to 226.00V -for now, as in minutes it can goes from 220 to 230!- while my PSU (20V raw, rectifiers, 1200µF, 7818, 47µf) dances from 18.85 to 18.89V, while the Flea's 7812 show 13.83 to 13.88. @L1 (wich is not there as the XO) it shows 5.05/.04. I have 15K at R1, as I have 2.2µF caps in filter...
Is it OK?
If no, may I change R1 even with 2.2µF?
Or may I remove the PSU's 7818 and let the 20V in?

About the opamps, as it seems it is the main debate on forums, is a ranking possible? I mean like 3 class, 3rd low cheap EOM ones, here JRC2114, a second class with not the best but still good sounding and enjoyed by some of us, and a 1st class, with the very best, maybe a top 5 where each of us may find happiness. Those this make sense? I think that may be a good help for newbies.

Have a good day!

[poynton]

Originally posted by Malefoda


............. the Flea's 7812 show 13.83 to 13.88. ...................

I really think that you are worrying too much !!!!!!!!!!

Andy

[6h5c]

Originally posted by Malefoda
Well, it seems there's also an "average minimum"...
My main dances from 225.00 to 226.00V -for now, as in minutes it can goes from 220 to 230!- while my PSU (20V raw, rectifiers, 1200µF, 7818, 47µf) dances from 18.85 to 18.89V, while the Flea's 7812 show 13.83 to 13.88. @L1 (wich is not there as the XO) it shows 5.05/.04. I have 15K at R1, as I have 2.2µF caps in filter...
Is it OK? If no, may I change R1 even with 2.2µF?
Or may I remove the PSU's 7818 and let the 20V in?

Have a good day!

Hi Matthieu,

Looks o.k. to me. Your Flea input voltage is above 18V and the output is a nice and stable 5.0V, so no worries here. As long as the first 7818 on the PSU has a minimum input of 20VDC then everything else behind it is o.k., it's all regulated.
15k for R1 is fine, there's hardly any current flowing there. The higher value nicely compensates for the capacitor being 2u2 instead of 3u3.

Regards,

Ray

[6h5c]

Originally posted by poynton
I really think that you are worrying too much !!!!!!!!!!

Andy

Me too, but I didn't want to mention it LOL .

Ray