Marantz CD63 & CD67 mods list - Page 498 - diyAudio
Go Back   Home > Forums > Source & Line > Digital Source

Digital Source Digital Players and Recorders: CD , SACD , Tape, Memory Card, etc.

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 6th December 2006, 09:11 AM   #4971
awpagan is offline awpagan  Australia
diyAudio Member
 
Join Date: Nov 2004
Location: sydney
Quote:
Originally posted by Chivvyp
The analog inputs are taken from R21 - R24 which are lifted at one end to disable the normal signal route.

Pete

Nice work Pete.

Class A opamp is still an opamp.
tried it various ways but still undecided????
I still had the opamp's signature just different amounts of signature.
personal choice i believe.

Ray's on sounds very good
http://www.diyaudio.com/forums/showt...t=#post1069399

allan
__________________
Indecision makes the world gone round.
Maybe
  Reply With Quote
Old 6th December 2006, 10:37 AM   #4972
Chivvyp is offline Chivvyp  United Kingdom
diyAudio Member
 
Join Date: Apr 2006
Location: London
At some time I have to decide whether to a) remove this output stage and go back to better dual op-amps (I have AD8620 in my CD67) and upgrade the filter with silver mica and 0.1%, or b) try to stick some adaptors in the output board and then try some other single op-amps ( I have some AD8610 on sockets in my PPA which I'd like to try).

In the meantime I have some Rubycon ZAs coming to put in by the DAC and the opamps and I'll probably lift the resistors near the output sockets as I think there's still a connection from them backwards through the DC block caps HDAM etc which probably isn't helping matters. Then I'll have a listen and decide whether to kill it via route a or b above

Pete
  Reply With Quote
Old 6th December 2006, 05:54 PM   #4973
diyAudio Member
 
Join Date: Oct 2006
Speaking of electrolytic capacitors...

A while back I wrote that I had used Panasonic FM series in a DVD player and found the results harsh. The original power supply caps were smallish Cerafine's.

Well, strike that. Yesterday I replaced the op-amps with LM4562's and put .1uf metalized MKP film bypasses on the analog and digital supplies to the DAC, and there was no more harshness. This Pioneer DV47ai is still no match for my less-than-loony modified CD63. It has more bass, but musical lines are much harder to hear. My CD63 has the stock transformer, regulators, clock, and only Pany FA electrolytics, so that could account for the bass.

The DV47ai has the stock Elna Tonerex DC blocking caps but I added .1uf bypasses. I could replace these with Black Gate N types, but I'm not sure the cost/effort is worth it. The stereo BB Dac chip has left and right analog supply pins, but Pioneer uses the same supply - not even separate bypasses. I think this is the source of the musical confusion, but it would be a major effort to address. Oh, well, some boxes have great mod potential and most don't!

FYI Yanks, Digikey has some surface mount LM4562 in stock now, but no dips yet.
  Reply With Quote
Old 6th December 2006, 06:23 PM   #4974
diyAudio Member
 
Fidelity Audio's Avatar
 
Join Date: Dec 2005
Location: Doncaster England
Quote:
Originally posted by markk02474

The stereo BB Dac chip has left and right analog supply pins, but Pioneer uses the same supply - not even separate bypasses. I think this is the source of the musical confusion, but it would be a major effort to address.
Remove the links or resistors to the left right supply (dac) and pop in 2 cheap regs and supply from 10+v from elsewhere and see how much it improves. Also change the caps after the regs.

Brent
  Reply With Quote
Old 6th December 2006, 09:44 PM   #4975
diyAudio Member
 
Join Date: Oct 2006
after all it is a bright breezy sound
  Reply With Quote
Old 6th December 2006, 09:53 PM   #4976
diyAudio Member
 
Join Date: Oct 2006
I'll explain "major effort". The audio board is on the bottom. Two daughter cards, the drive, 8 cables, and 20 screws have to come out to remove the audio board. Much more work than a CD63 and works poorly for listening after every change.

The chips are all SMD on the underside with 0.5cm clearance to the chassis bottom. The analog power traces to the DAC connect and run under it, so I would have to carefully pry up the two +Vcc legs and solder wires to them from the regulators+bypass caps. There's probably enough clearance to glue 7805/7905's + low ESR Ta SMT or small electrolytic bypasses to the underside. Its just not a project I'm eager for at the moment...
  Reply With Quote
Old 6th December 2006, 10:16 PM   #4977
diyAudio Member
 
Join Date: Oct 2006
yes but in the real world it is bright and breezy not a bad thing
  Reply With Quote
Old 7th December 2006, 10:37 AM   #4978
diyAudio Member
 
Fidelity Audio's Avatar
 
Join Date: Dec 2005
Location: Doncaster England
Going back to cd attenuation

I bought some Goldenjack -14db attenuators. They are well made and well soldered. I reverse engineered them to see what resistors they used.....lo and behold the same 0.1% resistors I used LOL.
The values do differ though. Where I used 1K78 and 475 ohm res (-13.5db) they have used 30K and 10K (-14db). Both 'L' type.

Time to test.

Brent
  Reply With Quote
Old 7th December 2006, 11:01 AM   #4979
AndrewT is online now AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
Hi Rowe,
the basic difference between your values and Golden are the source impedance seen by the power amp.

Using the usual ten times factor.
your 1780 & 475 suits Zin >5k
Golden 30k &10k suits Zin>100k
Some difference.

If you plug in some typical values for Zin you begin to see the effect.
Zin=10k and your attenuation falls from -13.5db to -13.8 db, an insignificant 0.3db change.
Golden's version falls from -12db to -16.9db. a very significant 4.9db change.

Similarly the RF filter will change it's time constant much more when the Rs of the attenuator is added to the series R inside the power amp. Golden's will roll off the treble quite badly, whereas your's will make a relatively small change to the treble, but still significant if the grounding cap is bigger than about 750pF.

When looked at from the perspective of the source feeding the attenuator then the load seen by the source is also very different.
Using the same Zin>=10k

Golden loads the source with >35k
your load is >2k2.
How many sources work well with loads over that range?
__________________
regards Andrew T.
  Reply With Quote
Old 7th December 2006, 11:18 AM   #4980
Chivvyp is offline Chivvyp  United Kingdom
diyAudio Member
 
Join Date: Apr 2006
Location: London
Hi Andrew,

Is ZIN the input impedance of the amp? I always had problems with working out whether this related to the power amp or the preamp or a combination of both

With my amp modules I believe the impedance is around 22k but my volume pot is 50K.

Does this make the ZIN 50K (or 22 or 72 or something more complicated)?

I chose my attenuation to match 22k on the basis that I'd fit a 20K pot in the future.

Regards

Pete
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



New To Site? Need Help?

All times are GMT. The time now is 09:14 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2