Author Topic: Marantz 94 mark 2  (Read 7229 times)

Offline stevenvalve

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Marantz 94 mark 2
« on: November 25, 2017, 01:50:22 AM »
Ian was over a few days ago with his full house modified Marantz 94 Mark2. He has spent many years perfecting it to this level. In its present state it is just brilliant and yes it has no valves. Its the only DAC that has been through this door that went neck and neck with my killerDac, it was very clean clear and noise free (one of his aims) Black indeed around the notes and they appeared to come from empty space. The sound stage is not as big and it does not have quite the bloom as the KillerDac, but is very similar in timbre and texture as mine and what i really like is it is not bright or white, instruments sound real, unlike most digital playback. It has none of the slow plodding nature of standard Marantz 94s. It is relaxed, natural, smooth, and has presents, with a solid image focus, yum its nice. Shows you can build brilliant from just good. But before you run out and buy a Marantz 94 remember he has spent many years tuning this machine and he knows how to get all the hard to find esoteric capacitors and resistors, and most are not commercially available. Anyway i will not rave on any more, but hopefully he can come to this page and explain how it works. The pictures do not show the full story, because underneath there is a compartment stuffed with more toys. I really could live with this Marantz because it makes Music, They should have built them like this in the first place.
« Last Edit: November 26, 2017, 07:24:10 PM by stevenvalve »

Offline vitavoxdude

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Re: Marantz 94 mark 2
« Reply #1 on: November 25, 2017, 11:40:29 AM »
Hi Steve and Ian :)
Yes indeed it would be great hearing a blow by blow account of the upgrade path Ian has traveled in order to be able to be praised by SG!!!  It must have a couple of great sounding TDA chips inside it then.  What other equipment is the CD spinner being used with??

For something with OP-amps in the output chain it does not always mean it's bad............I recently put some dexa discrites in place of some OP-amps and was shocked at how much better it performed all round. I tired to avoid the more usual Burson's etc.

It is easy to spot  a lot of the changes implemented, the changed dac decoupling caps, the obvious clock board and the diode replacements.  I remember those original POOGE articles and that couple of hundred page Marantz CD65 upgrades on the  DIY hifi site.

I would love for Ian to describe the process and give a guide to the uplift various stages took on.  This website could do with more helpful information and it will bring increased readership I feel.  ;D ;D ;D ;D
We all like different things so lets all agree to disagree and if any common ground is found then worship it.  Mine is the KD hence being present on this forum.

Offline brenden

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Re: Marantz 94 mark 2
« Reply #2 on: November 25, 2017, 01:18:58 PM »
Hi guys . I am travelling back home to Newcastle  at the moment. Rest assured  I will    post a detailed account  of  my  experiences  with  the Marantz cd 94 mk 2 as well as  other equipment  upgrades.
    One thing I will say now is that it is a holistic approach rather than using a super  TDA1541  double crown chip for example .  You need to reduce noise in every circuit  because its all connected .
  In digital ,  added noise means jitter . Capacitor quality  both in Electrolytic  and   film bypasses are critical to take things to the next level . Attention to clock power supply is critical as well as  the decoupling caps around the TDA1541  ( super sensitive )  .
     Thanks again to Steve  and Jen for being so welcoming   .It was an absolute  pleasure  to spend  quality  audio time   at their home . 

Offline brenden

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Re: Marantz 94 mark 2
« Reply #3 on: November 26, 2017, 03:26:36 PM »
  Its difficult to know  where to  start.  I could seriously  write a book  about  my  experiences .
       i bought   myself  a brand new  Marantz cd 94 mk2  around 1990  , but i was never satisfied with my sound  and , after being on the merry go round  for a number of years  buying and borrowing high end equipment it seemed that every substitution  always had tradeoffs  when it came to  musical satisfaction.
     My gear was mostly excellent  design and  build  quality  such as the Stax mono blocs Classe DR6  so  I came to the conclusion  that  it would be worth modifying  my  gear to  add refinement   to the reasonably  dynamic sound i had .
  During the late 90s i had performed literally thousands of mods  and built up a memory bank of  practical  experience  in what  worked and what didnt  . Not knowing  aĺl that much in theory  I wasnt constrained  by preconceived  ideas   so I tried  lots of radical  stuff back then . I was even running  battery clocks  a decade before  i realised there were other  nutters out there 😊 . Eventually  i   achieved  excellent sound  quality   through perseverance   and trying to understand  why things changed . For example this led me to studying capacitor construction  quite intently .
     Not algebraic  theory mind you   ,    rather , what different construction  and materials   bought to the  table  in a practical  sense .

    Anyway ,   kids came along  and  the system was totally  dismantled  sold or stored .
 
 A few years ago i decided  to  rebuild  a  sound  system   based around  the 94   and was confident  i could improve on my original.
 
   The  Marantz cd  94  machines  had all the ingredients  for greatness . Arguably  the best  drive  ever made in the CDM 1   and possibly  the  best  chip  ever made  in the tda1541a  ,excellent  multiple regulated power supplies   with  generally  good parts quality   for a commercial  product.

   So what do we do  to improve it if its so good ?     Well the devil is in the details.

      Firstly , to achieve  greatness   ,a component is only as good as its weakest link.  There is no single  place to start  really .Its a matter of  identifying and working through every single weak link till they are all eliminated or  improved  .
           
        In the  90s  I did a shootout  with probably  20 different op amps   .The bottom line without boring everyone  about the differences  was that the  AD 827    and  AD 847  were the clear favourites being excellent in all areas  including dynamics  which seemed to be a problem for many op amps being too smooth or bland  . The originals  in the 94 also had good dynamics  but are coarse   or ragged  in comparison.
 
   These are the op amps in my machine today .  Not cheap   but  very capable.   Op amps upgrade probably gave a few percent of the  improvement  in sound quality  so dont expect miracles  from  any  single mod or you will be sadly  disappointed   as with any of the other mods  in isolation  .As I said  it is a wholistic approach   with each  mod being rather small incremental  improvements
       I will detail some more of  the 94  changes in a number of posts as  there is a fair bit to get through  ,so i will end this one  for now .. Cheers Ian .

Offline vitavoxdude

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Re: Marantz 94 mark 2
« Reply #4 on: November 26, 2017, 03:56:55 PM »
Well, I for one will look forward to your audio travels IRT the Marantz silver spinner.  Of course having two of them I have an obvious interest on finding the things that worked  ;D
We all like different things so lets all agree to disagree and if any common ground is found then worship it.  Mine is the KD hence being present on this forum.

Offline stevenvalve

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Re: Marantz 94 mark 2
« Reply #5 on: November 26, 2017, 07:19:47 PM »
Time to buy a Marantz 94. Some say the Marantz 94 with a single chip was a better idea than the mark 2, with 2 Chips. They feel going to the two chips compromised the performance in some ways. I have no idea, any thoughts. Question is buy a mark 1 or 2.

Offline brenden

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Re: Marantz 94 mark 2
« Reply #6 on: November 26, 2017, 08:26:38 PM »
Great question Steve ,and one i have wrestled wit a lot . I owned both at the same time and compared them side by side . Firstly the mk2 had a bit more weight  . It probably  had  more drive due to the  doubling up of dacs and amplification  stages  in dual differential .
    The mk1 was a bit sweeter  and  and  maybe a bit less grungy . This was almost certainly due to the better film caps around the tda1541 a   even though they werent great caps ( mylar ,   inductive)
     Certainly not optimum .   As you could hear   ( comparatively ) grungy plodding in the mk2  can be  totally fixed .

    I am not 100 pc sure the weight of the  mk1 can be  made to equal the mk2   but certainly could be improved  .
     I think the dual differential architecture is superior  as far as noise and distortion  are concerned  but  the extra room in the mk1 opens up lots of  possible  choices for  even better   exotic decoupling  caps around  the tda1541  and for top line caps the cost will be  halved  needing 14 instead of  28 .
      The caps in the CD12 and CD 7  around the dac were  top quality  non inductive  polypropylene foil types   i believe .   These would be impossible  to  fit on the tiny mk2 board  .I was lucky enough to get a few of those green  pps copper foils for mine ,  but they are no more The only ones I have ever seen are the ones i got .
   The mounting arrangement for the dac board in the mk 2 is also not optimum either  , using steel prongs . This will be the last thing I will do .My last one was hard  wired with Discovery signature  wire .really nice wire and made a clear difference.
       
     
 
       

Offline zenelectro

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Re: Marantz 94 mark 2
« Reply #7 on: November 26, 2017, 10:18:58 PM »
Great question Steve ,and one i have wrestled wit a lot . I owned both at the same time and compared them side by side . Firstly the mk2 had a bit more weight  . It probably  had  more drive due to the  doubling up of dacs and amplification  stages  in dual differential .
    The mk1 was a bit sweeter  and  and  maybe a bit less grungy . This was almost certainly due to the better film caps around the tda1541 a   even though they werent great caps ( mylar ,   inductive)
     Certainly not optimum .   As you could hear   ( comparatively ) grungy plodding in the mk2  can be  totally fixed .

    I am not 100 pc sure the weight of the  mk1 can be  made to equal the mk2   but certainly could be improved  .
     I think the dual differential architecture is superior  as far as noise and distortion  are concerned  but  the extra room in the mk1 opens up lots of  possible  choices for  even better   exotic decoupling  caps around  the tda1541  and for top line caps the cost will be  halved  needing 14 instead of  28 .
      The caps in the CD12 and CD 7  around the dac were  top quality  non inductive  polypropylene foil types   i believe .   These would be impossible  to  fit on the tiny mk2 board  .I was lucky enough to get a few of those green  pps copper foils for mine ,  but they are no more The only ones I have ever seen are the ones i got .
   The mounting arrangement for the dac board in the mk 2 is also not optimum either  , using steel prongs . This will be the last thing I will do .My last one was hard  wired with Discovery signature  wire .really nice wire and made a clear difference.
     

WRT 94 MKII:

They run dual differential but still do L and R ch in same DAC. So one TDA does L+ R+, other does L- R-.
Would have been better to use 1 x TDA L channel +and- /  other R channel +and- but as they say, it is what it is. :)


They also used 5 opamps / channel in the dual dif configuration which was fairly complex.
Maybe this was to allow for FET switched de-emphasis circuit. I'd be pulling that out.

A simple 3 opamp config with class A opamps is the way to go.

I never tried the AD827 / AD847, however I got great results with OPA627 biased into class A
I recommend biasing them into class A - I have never found an opamp that didn't sound better with class A bias.

But as you say it's all a balancing act. The opamp PS bypass makes a difference too. Some people use double
caps, ie; electro with film cap but I think this gives slight artificial sound. With the 827 / 847 you have to be a
little careful as they are very fast and can oscillate. But it will usually not sound right if this is happening. 

I used to enjoy doing this sort of simple modding to SS gear, it can be a bit maddening at times - this opamp,
that cap, etc etc

Oh and it's also worth trying running the analog OP stage straight off batteries with no regulation.
This can sound really good - if you don't mind being a battery slave..... charge etc  :-X :)

T




Offline brenden

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Re: Marantz 94 mark 2
« Reply #8 on: November 27, 2017, 01:54:58 AM »
This is the clock with integrated  power  supply   all caps replaced  one by one and assessed . Mostly Silmic 2 super golds  but Silmic 2 standards very good too.  Bypassed with Jupiter copper foils  and  pps copper foil caps  This lowered the  subjective noise floor immensely . I also added a couple  of film caps very close to the active  devices underneath .

  The Silmics are much better than the supplied panasonics and philips caps
   Not shown is a larger cap in parallel with the  power supply  . I think from memory 4700 uf  elna for audio . The two 1000uf caps are just not enough for the clock .Much better  sound with the bigger
   capacitance .   The clock power supply needs to be as noise free as possible and very reactive  .so dont skimp on .01 bypasses .  Dont  use mylar here .

  What seems to be most important here is to get the power supply to the clock as noise free as possible   .noise means jitter .  Jitter means loss of fidelity .
    Would love to try a Zen clock here one day Terry . ☺



Here is also a photo of the  new Valab clock  with original capacitors   .
« Last Edit: November 27, 2017, 07:48:28 AM by brenden »

Offline brenden

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Re: Marantz 94 mark 2
« Reply #9 on: November 27, 2017, 02:23:46 AM »
Here is a photo of the  big cap beside the clock  module held in place by a resin capacitor  clamp on ths base of the 94 .
« Last Edit: November 27, 2017, 03:10:30 AM by brenden »

Offline brenden

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Re: Marantz 94 mark 2
« Reply #10 on: November 27, 2017, 03:45:38 AM »
Here are the  tda1541 chips  with  the Panasonic pps copper foil capacitors

Offline zenelectro

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Re: Marantz 94 mark 2
« Reply #11 on: November 27, 2017, 10:53:19 AM »
Ian,

Nice work. Quick question - Are you running digital filter or 0 x OS?

T

Offline brenden

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Re: Marantz 94 mark 2
« Reply #12 on: November 27, 2017, 01:14:59 PM »
Hi Zen  , its Non over sampling .

Offline brenden

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Re: Marantz 94 mark 2
« Reply #13 on: November 30, 2017, 12:19:29 PM »
Moving along . The player has been converted  to non oversampling  using  99.999 annealed silver wire in teflon tube.  Also added a couple of copper foil pps  .01 bypasses  closer to the chip 
     Attached photo .
« Last Edit: November 30, 2017, 12:23:06 PM by brenden »

Offline brenden

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Re: Marantz 94 mark 2
« Reply #14 on: November 30, 2017, 01:42:03 PM »
I have boxed in the Duelund output capacitors underneath the player . There  isn't  enough  room  to fit them inside . To  access underneath I simply need to unscrew the box section .the caps are affixed to the  inside of box with double sided tape with some insulation over the caps and on the  cd base plate.
   None of this can be seen unless your eyesight is level with the underneath  of the player .
    This will be improved once modding is finnished with better and shorter wire and neater insulation .
   I cut a small slot in the baseplate  for the wires  so the base plate can be removed without unsoldering wires .
  The wires tuck in neatly to the space at the end of the box   once fitted .
  The box was the lid part of an electronic  box from Jaycar . Perfect for this application .
« Last Edit: November 30, 2017, 03:40:18 PM by brenden »

Offline brenden

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Re: Marantz 94 mark 2
« Reply #15 on: November 30, 2017, 04:00:29 PM »
Here is a better  view of  the clock mounting .
   I screwed  two  solid brass standoffs  that had to  be extended a bit to get the exact length .
    The clock board  is very strong and rigid  so it sits suspended above the marantz pcb toward  the front of the  player . Some of these jobs are very finniky and time  consuming but worth the effort .
  It had to be just above the marantz  pcb but leave enough room  for  the  larger caps to fit under the  lid so the standoffs had to be measured perfectly .


Offline brenden

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Re: Marantz 94 mark 2
« Reply #16 on: November 30, 2017, 04:14:05 PM »
The cap to the left is actually a beautiful Elna 6800 uf   35v big Starget . Wonderful caps . This is in parallel with the two silmics on the clock . I used a  resin capacitor clamp  Again , a very tight fit .
    The size  and the quality of the capacitance  is extremely important  here . It makes a big difference  over the standard  clock .  I ended up using  Jupiter  copper foil .01 for bypasses  which sounded best there but  auricaps  would have been good too .
   The clamp is a snug fit around the capacitor but not too tight so I can slide it out  if I want to work on the clock  without  unsoldering .
« Last Edit: November 30, 2017, 04:54:52 PM by brenden »

Offline brenden

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Re: Marantz 94 mark 2
« Reply #17 on: November 30, 2017, 04:46:45 PM »
Another very important upgrade is the  6800uf cap in front of the two main filter caps  .
     The cap  Marantz  used is a lower grade Elna  cap  with steel leads , but is used to filter the critical  digital circuit . I used the 6800uf  Elna  Starget here too .they have a beautiful rich but clear sound  and is bypassed underneath with a copper foil  polystyrene  .01uf.  This is way better than the stock cap  with a very noticable  lift in sound  quality.  Again , had to do some  mucking around to fit this much larger size cap into this spot including moving a resistor to the underneath  of  the  player.
  The two  Jupiter  copper foils   are bypassing  the  main  filter  caps  ,giving a rich ,natural liquid  sound   .Big improvement.
« Last Edit: November 30, 2017, 05:02:40 PM by brenden »

Offline brenden

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Re: Marantz 94 mark 2
« Reply #18 on: November 30, 2017, 11:51:59 PM »
Vitavox picked  up  the diode changes  in an earlier  post  . On this board I have only done one lot  so far .There three lots of power supply diodes  and i have done this to other machines before and will eventually  get the treatment..  You are probably  wondering  why the huge diodes ?
  Well ,they are hexfreds ultra fast soft recovery (with the soft recovery part being the important bit )  and the ones I have used from different manufacturers  like Harris HFA   and international rectifier types  sound similar . The  ones I used in my first machine   way back  were the hfa08tb60   from memory they were in a smaller package  and the legs had to be bent  heavily to get them in .So i gave the big ones a try and they sounded just as good  but the legs , being  much  wider made it much easier and neater  to fit .i cant recall which ones these are probably the hfa 15  or 25    way over rated  😊.  I did compare to shotkey  diode way back but preferred  the hexfred .I thought the shotkey diodes lost somerhing on the top end  sort of like a treble cut in comparison .Some people  like them but i prefer the Hexfreds . These diode replacements  will reduce hash   and  are another welcome improvement . Like i said before  , its the cumulative gains that get you there  .
« Last Edit: November 30, 2017, 11:57:25 PM by brenden »

Offline zenelectro

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Re: Marantz 94 mark 2
« Reply #19 on: December 02, 2017, 11:31:06 AM »
I have boxed in the Duelund output capacitors underneath the player . There  isn't  enough  room  to fit them inside . To  access underneath I simply need to unscrew the box section .the caps are affixed to the  inside of box with double sided tape with some insulation over the caps and on the  cd base plate.
   None of this can be seen unless your eyesight is level with the underneath  of the player .
    This will be improved once modding is finnished with better and shorter wire and neater insulation .
   I cut a small slot in the baseplate  for the wires  so the base plate can be removed without unsoldering wires .
  The wires tuck in neatly to the space at the end of the box   once fitted .
  The box was the lid part of an electronic  box from Jaycar . Perfect for this application .

Wow - you have done a lot of work. I wish we could have spoken earlier - read on.

With a 2 DAC / differential to single ended arrangement such as the 94MKII, the output circuit can be direct coupled with no caps required.
This is always the best way to go if possible - it saves money and no cap is better than any cap in signal path - even Duelunds.

However the circuit needs to be a proper DIF -> SE design and it needs a small trimpot to null any offset at OP. This can be done pretty simply with 3 opamps.
The standard circuit uses 5 opamps per channel and is pretty complex. This is mainly because it incorporates Fet switched de emphasis which you don't need.

The opamps should be biased into class A - but the right amount needs to be tweaked.

The standard regulators are either 317 or 78xx type which don't filter or block rubbish coming from other parts of the player above a few kHz very well.
Once you get to 100's of kHz they almost stop working all together. This is one reason why your PS cap changes make so much difference, they are
doing most of the filtering work of the regs.

For regulators I use very simple discrete series pass or shunt are even better. These regs work right up into the MHz range at filtering incoming rubbish.
They also have much lower noise than 317 / 78xx regs - but I'm not totally convinced the random noise is a big issue.
It's also best to use separate regs for R and L channel.

All this can be made on a relatively small ground plane covered board with room for caps, resistors and with opamp sockets.
The baseline performance is a long way above what the standard CD94 gives you.

Then it's a case of tweaking resistor and cap types, opamp types and amount of class A bias to get everything sounding best or to your taste.

T