As with most budget conscious CD-Players, one of the most inadequate parts that make up the whole is the Chassis/Case. Marantz's Ken Ishiwata has realised that himself and therefor the MAIN improvement the SE-Series CD-Players received was purely mechanical.
A Cross-brace is added to the rear part of the chassis and a substantial Bottom Plate is added too. Anyone who has access to a metal-workshop can do that him- or her-self. I decided to pay the additional money for a CD-67-SE as I have not got anything suitable around.
Still, even for the "improved" Version of the CD-67, the Chassis and "hood" are quite resonant. It is very easy to apply some effort here. I purchased some self-adhesive Bitumen Pads usually sold as damping Material for Cars (aka - Dead-sheets). It is very easy to work with, just use a standard utility knife and a steel ruler to cut the stuff.
I used overall about three and a half sheets of a 12" X 12" size. I applied one layer directly to the additional Bottom Plate. Knock-knock - better, but not quite there yet. To get at the inside of the Unit's chassis You need to dismantle the entire unit. You may not want to do that. In this case skip the next Paragraph, the improvement from the single layer should be quite notable as it is.
After I had everything removed from the Chassis and all Connections disconnected, I started to apply small rectangular Patches to the Sides of the Chassis and at "nodal" Points around the Bottom. The Idea is not to obstruct anything, yet to achieve a maximum damping effect.
If you have not taken the whole unit to pieces, at least remove the cross-brace and apply some Bitumen Strips to it's underside. Do not forget to put the thing back (I did forget twice). Now take the Hood. Apply one complete layer of Bitumen Pads to the Top (inside of course). You may want to possibly put two layers there. Apply one rectangular strip each to the sides (inside again) of the Hood making sure not to foul the holes for the Screws.
On top of the Transport there are two grooves or indention's which are easily fitted with one small rectangular piece each. I also applied a layer to the area in-between these two, but it is essential here not to foul the Mechanism. I also applied one small patch to each side of the Transport unit. This is done best with Transport removed (as some of You have done earlier). If you did not dismantle the whole unit, skip this step.
As finishing touch I did replace the stock Feet with a set of three "Spike-dampers" from Goldring in a three-point arrangement (two in front, one in the back). These Spike-dampers did cost me about thirty British Pound, feel free to use Your favourite "footwear" in this place. I glued the included "cup's" to the underside of the chassis and use the "Spike-dampers" Point up.
This was easy, wasn't it? Now one last look, check nothing is askew and re-assemble the Unit. Plug in and enjoy the Music.
After posting this to the Joe-List I received the following from David Barnes:
Thanks for the modification idea, I will employ it on my 63SE. An alternative to the spikes is Norsorex spheres al a Audioprism's Isoshperes. Edmund Scientific has these as part of a experimenters pack labelled "Happy and Unhappy Balls" . For $5 US, these come with one regular "super ball" (happy ball) and one Norsorex ball (unhappy ball) perfect for use as feet.
To keep these from rolling around, I used metal washers available from any hardware store to set them in. It's a nice tweak for CD players, turntables and even VCRs.
Given the Price-point the CD-63/67 Series sells, it is unavoidable that the electronic part of the Unit has been subject to some cost-cutting. On closer inspection of my CD-67 SE I found that there where any number of things I would have liked to see, but didn't.
For the CD-63/67 there are a number of small Part's upgrades that can be done. Some of things I will mention simply bring the unit in line with the SE-Model, others do go beyond the original. I will not reveal Marantz's "secret" HDAM Circuit, to upgrade the 57 to 67. Buy a Service-Manual and it is all covered. So anyone owning a CD-57 can upgrade the Unit easily with this circuitry.
As said Marantz uses the JRC 2114 Op-Amp, not really that bad a unit. They use the same Op-Amp in the CD-17 (but not the CD-17 KI-Signature if I read correctly). In the end of the Day however, the 2114 is little more than a pepped up NE5532. I'd say out with it.
I personally prefer the LM6172 from National Semiconductor over all the others. It is a Voltage Feedback Op-Amp which is build fully symmetrical for the + and - half, has extremely low distortion (THD + N at 2 Volt P-P into 100 Ohm at 10kHz is below -100db), extremely Wide Bandwidth (100MHz at Unity Gain) and can drive about anything (it is designed to drive over 5 Volt rms into 100 Ohm at video frequencies). Noise is comparable to most decent Op-Amps (about 10nV sqrt Hz). The IC is based on a fully symetrical layout and indeed is a monolithic implementation of a circuit similar to the new "current-mode gain" Circuitry Krell uses in their latest products. Accuphase also uses discrete implementations of similar Circuits.
A bit more care must be taken with the Power-Supply when using this Part, but I feel the Performance is very well worth it. I think that the fact that these Op-Amps have such a exceptional wide Bandwidth is responsible here. You see, the NPC (Nippon Precision Components) DAC Marantz uses has a "raw" PWM (Pulse Width Modulation - read digital) Output. Unlike many other Delta-Sigma (or Bitstream) DAC's the NPC Part does not incorporate any analog filtering. Thus the analog Filter is exposed to significant levels of RF (I measured several hundert millivolt at the Inputs of the first Op-Amp). Any Op-Amp that has a more normal Bandwidth will distort substantially with these Frequencies, causing intermodulation and thus signal-dependent artefacts that are audible.
Currently no-one in the UK seems to carry this Unit (I got mine as engineering Samples from Nat Semi - ThanX Guys), but apparently Digi-Key sells them in the States. This Unit is more expensive than most possible replacements, but MUCH better sounding. I came across them in the context of Modifications to ADAT Recorders (Digital 8-Track units recording on Video-Tape - neat).
With all this palaver finished, unsolder the old Op-Amps and put the new ones (whichever you choose) in. If you have a CD-67 SE from the same Production run as I do, the PSU Capacitors associated with these Op-Amp's will be Elna "Starget" ones. They have a metallic red sleeve. These are good ones, leave them where they are. The Service manual actually specifies standard Units here, so chances are You have a set of cheap and nasty Cap's here. Replace with your most liked flavour of High Quality Audio Capacitor (Elna Starget, Black Gate, Sanyo SG Series OS-Con, Nichicon Muse...). The Circuit-board denominators are C611,612,613,614. They are 100uF, much larger will not make much of difference (IMHO).
Regardless of whatever exotic Cap I use, I always stick a 10-22nF Film bypass Cap across it. How I do this depends on the Layout of the Unit. In the Marantz they ended up directly across the electrolytic Cap's on the Solder-side of the Board. I used the small yellow 22nF 63 Volt WIMA ones. As these have recently become scarce, may I suggest to use Panasonic "stacked film" SMD Capacitors instead. These are carried by Digi-Key in the US and RS/Farnell in the UK. Any value from 22-100nF will be okay, but it makes sense to go for the highest available voltage rating.
Next stop should be the Filter capacitors. In the CD-57 they are Ceramic, in the 67 and 67SE they are Mylar.
The Circuit-board denominators are CD21, CD22, CD23, CD24 (120pF); C605, C606(1000pF) and C607, C608 (100pF). I did replace them all with Philips 1% Polystyrene Capacitors.
Looking at the analog Filter in Pspice, I noticed that the Filter has slight "bump" in the upper treble. While this is small, I had a look around how to change this, as I felt that CD-Player was too bright anyway. Replacing C607 and C608 with a slightly larger value unit will help. I used 150pF (again 1% Philips), but up to 220pF seem workable. Try out various values for Your desired result. With 150pF the -3db Point of the Filter is changed to about 30kHz from 40kHz in the original Version.
Last in line is the Output Circuit. In the CD-57 this is simple as no HDAM-Buffer is used. You will find two electrolytic Capacitors "back-to-back" per Channel. These are C655, C656, C657, C658. In the SE-Models (and KI-Signature) they are ELNA "Silmic" 220uF units. The CD-57 and 67 use standard units. They do not block any (significant) DC and I consider them safe to remove. Just unsolder them and replace with a piece of wire.
In my Case, I had the CD-67 SE and the benefit of the "Silmic" Cap's, so what do we do with them? I used them to replace the Output Buffer's PSU-Capacitors (C651, C652, C653, C654) and again also bypassed them with 22nF WIMA Film-Cap's.
Having had such success with LC decoupling in the Digital Department (see below), I also introduced it in the analog Circuit. Here R613 to R616 and R 651 to R654 where replaced with 2,2mH (If I can read the coding correctly - they where salvaged from some board) Axial Inductors with a measured DC of 1.5 Ohm. This is a much better solution than just shortening these Resistors out as it is suggested by a number of People.
Lastly the Circuit uses two Transistors to Mute the Player on Power-up. This is not such a nice Idea if You ask me. Just unsolder QN05, QN06, QN07, QN08. You may however want to hang on to them, as one fellow Internetter disliked what he heard after removing the Muting Transistors in his Pioneer CD-Player.
I did also replace the Output Jacks with something better (the Originals have the Ground gilded but not the Signal-pin).
In the last two parts on the CD-63/67 Series CD-Player modifications we have "behaved" ourselves. No "magic" tweaks. No magic components. No Zen transcending the ordinary. Implementing all the modifications from Part one and two will certainly make the Unit you are working on a more competent, more enjoyable Player. It will however just not make the Step beyond only being a competent CD-Player though. And that is a shame.
Fret not my fellow AMA Member (Anonymous Music Addicts - I hate the word Audiophile - it sounds like some kind of deviant sexual behavior). The cure for digitalitis is close.
We can scale this mountain with a lot of patience and little money in Parts. Parts are Parts are Parts are Parts - or are they? Let's consider. I do have a background in industrial electronics. That by default means mixed-signal environments.
A CD-Player is also a mixed Signal device. It contains a number of High-Speed Digital and DSP (Digital Signal Processing) Chips. Compared with the latest Pentium MMX or Power PC Chip the unit may seem to use low clock-speeds (~17MHz). But then, we have a much faster Device here than the many 386 Processors. And we want music, scale, dynamics and resolution from the unit not just number-crunching.
As many people can attest, that is a very tall order. Someone noted that for even only 16 Bit resolution the bottom-bit comes in at about 80 microvolt. That is not exactly a lot. We really need to turn back to my mixed signal days in the 80's and my experience with servicing radio-frequency-equipment to come up with improvements.
So here goes. First of all, the CD-Player uses a Ground-plane (split between digital and analog). That is good. The HDAM units in the better Models are shielded with copper. The rest is wide open.
Here's tweak one: get some very thin copper (ideally self-adhesive Foil sold for anti-EMF treatment) and shield all IC's. I essentially wrapped some around the Op-Amp's (take care not to shorten out any pin's). I scratched some of the lacquer away from the top of the PCB near the Op-Amp-cases to expose the copper of the Ground-plane. I soldered these shields directly to the ground-plane. Solder very carefully here as You may fry the Op-Amp's otherwise. Let the Shield cool down if You need more than one attempt.
I also applied similar shields to the DAC and Decoder IC (small many-pinned Surface Mount Devices below the PCB). For the DAC I connected the shield to the ground below the DAC. The shield on top of the Decoder (SAA73272 - Q102) was connected to ground with a very short "jumper-lead". Soldering these shields is even touchier than the ones on the Op-Amps. Make sure You have a steady hand.
Finally we have the Micro-Processor (large Chip in the Front of the Board). This is certainly a source of RFI. Again shielding with some Foil helps.
If you cannot get Copper-Tape or similar material (I used extremely thin copper sheets, cut to size with small scissors and glued with Contact-Glue), you can use self-adhesive Aluminium Tape, which is widely available. Soldering this is fairly difficult though. Special Solder to solder Aluminium is available (Maplin does the stuff in the UK). It contains very aggressive flux and needs very high temperature to work. I had success cutting this Tape to size and soldering Jumper-wires on while still having the paper on the back. About one of three attempts yielded a Piece of Aluminium that could still stick. After that I cleaned the flux-residue off using isopropanol Alcohol. This is so much trouble that I go miles for a bit of Copper these days.
I "finished" the whole process off with small square pieces of Bitumen Pad (see part one), each roughly the size of the IC it was destined for. The Idea here is to "damp" the Chip. I have no clue if it works or not, it didn't cost anything (I used cut-off's from Part one) and cannot do harm in our case. Other pieces of electronic may stress the chip's used more, causing them to get hot. In this case I'd leave the Bitumen Pad off. Small Heatsinks are available for Op-Amps and the like. These should also help in "damping" the Chip and will help to run the Chip cooler.
Next Stop, the Digital Power-Supply lines. We have already established, that we are really dealing with a complex mixed signal unit here. Many Circuit traces carry substantial currents with high frequencies. All that pollutes the PSU lines substantially. Check it out if You have a 'scope. Nice and furry traces where we want to see pure DC. Even worse, these long circuit traces make brilliant aerials, both receiving and transmitting. I found the amount of RF-hash on the PSU lines quite worrisome.
Marantz uses standard Electrolytic Capacitors, Resistor-Filtering and leaded Multi Layer Ceramic (MLC) Capacitors of small Values to control all the RF. Not very effective.
I read a lot and modeled a lot and took some educated guesses and some "gut-feeling" to come up with the following:
Find RD01, RD04 (near the DAC-Chip) R117, R118, RF01 (near the Micro-Processor Chip - between that Chip and the Transport). They all look the same and stand out. I replaced these with 1mH miniature Chokes (14 Ohm DCR). These Chokes have a self-resonance of around 1MHz (my ones came from Maplin). They look like large resistors. Now 1MHz is not enough for us. We need to extend the effectiveness here to much higher frequencies. Enter three small Ferrite-Beads each (sold in bags of 10 for pennies). These are threaded onto the leads of the Choke, usefully extending the effectiveness to very high frequencies.
As mentioned before, the Capacitors used by Marantz in the digital section are also nothing to write home about. So out go C126 (on the small board attached to the Transport), C157, C114, C120, CF02 (all 47uF 16V), to be replaced with Nichicon PL Series ultra low ESR Types. I suggest to use 100uF 50Volt (my ones are from Maplin). Alternatives are Panasonic HFQ (sold in the States by Digi-Key - unavailable in the UK use 120uF/25Volt). Elna RSH should work too. Please do not use "Super-low-Z" units (like the Panasonic FA Series).
All of these have small ceramic bypass units on the Board. I did solder 100nF 50Volt X7R 1206 Surface Mount Capacitors (from AVX/Kyocera use others at your peril) across them below the Board. Some of these 1206 Cap's where placed as close as possible to the IC-Pins, but that is again very delicate.
Similar configuration where used around the DAC. I replaced CD04, CD07 with 220uF/50Volt Nichicon PL Units. For CD15, CD16 I used 470uF 50Volt. Here I removed the original ceramics (CD04, CD06, CD12, CD13) in order to place my 100nF SMD Caps as close to the Pin's of the DAC as possible. Again, soldering these SMD Units is a tricky job. Steady hands and a small Soldering iron are a must.
From the final PSU mod's I now had two 470uF "Silmic" Cap's to spare. What to do with them? CD15 and CD16 near in the DAC's analog PSU-Lines where so far Nichicon PL Series ones. Why not try the Silmic? So in they went..
DO NOT REMOVE ANY OF THE ORIGINAL CERAMICS UNLESS YOU REPLACE THEM!!
Having modeled this PSU-Decoupling arrangement in PSpice (thanX to Guido for supplying me with data on the R & L values for Ferrite beads) it seems that the suppression of RF-Hash from this arrangements is about 40db more effective than the original Circuit. Traces observed on the 'scope are clean. (added later) I just went back and checked it out. The maximum amount on any (analog or digital) PSU Line is about 500uV or about -80db (for 5 Volt). The Amount of RF directly at the PSU Pin feeding the Digital Filter is substantially above 20mV. The AC on the PSU Pin leading to the X-tal Oscilator on the other hand is squeaky clean. Absolutly nothing there (or at least substantially below 150uV at 2MHz or so).
Also, after I posted the original set of Mod's using the Ceramic Chip-Caps I had a chat with Andy Groove (Mr. Ankoru) from Audio Note UK about digital decoupling. He says that the Black Gate PK Series of Capacitors works well. Similar to my Nichicon PL-Series / 1206-Ceramic Combination, the Black Gates are effective to over 100MHz on their own.
This of Course will only work if You can keep the inductance from the Leads and the PCB-Tracks low. Thus these Cap's would be placed best with ultra-short leads below the PCB. The Black Gate PK Series also seems to be limited to values of maximally 47uF.
If you feel not exactly like messing around with minuscule SMD chip-Caps, You may want to try these.
I have done some more thing in the digital domain. The Quartz Crystal used by Marantz is fairly small. This may or may not be bad, but experience told me, that chunkier and heavier Components tend to be better. Thus I used a larger (mechanical) Crystal Unit to replace the original unit. I put the original rubber grommet back onto the new unit.
I replaced all Digital Signal-lines from Decoder to DAC with 50 Ohm Miniature Coax.
This comes series-terminated via 1206 SMD 47 Ohm carbon composite resistors. I took the appropriate pin's of the decoder-chip of the PCB (extreme care or you break them off) and soldered the resistors directly on. On the DAC-Side Marantz was kind enough to provide convenient Solder-pad's. I went through about 15 resistors and ten length of mini-Coax until I had it sorted (too large soldering iron). I feel that the work was worth it though. Digitalites is gone!
PLEASE NOTE THAT THIS IS A VERY ADVANCED JOB. IF YOU ARE NOT SURE WHAT TO DO AND HOW, DO NOT ATTEMPT IT. If you mess up at the step above, you may render the Player unusable and irreparable (at least economically)!
That pretty much sums it up. I also installed a 75 Ohm BNC Connector instead of the original RCA style Connector for the electrical digital Output. Almost all better DAC's here in the UK use BNC Connections, so this seemed a sensible step while I was inside the unit.
Many of You may have wondered, why I have not replaced he Regulators with some exotic stuff or similar things? Well, even the worst 3-pin Regulators do a fairly decent Job as far as keeping the Voltage constant. Even noise-levels are pretty low.
If you want, you can use the better Linear Technology adjustable Regulators (LT 1033/1085) or even the Didden/Jung Op-Amp + discrete Regulators. You can use the LM340T5 for the two 5-Volt Regulators. These Units are pretty good in digital circuits. I swapped Q811 (a 7805 Regulator - supplies the DAC and Decoder-Chip) for a LM340T5.
In my Unit all other the original Regulators stayed in place. I decided however to beef-up some of the Capacitors in the PSU. Now in the analogue PSU for the 67 Units, Marantz uses two more "silmic" Capacitors of only 470uF. This seems highly suspect, but Ken Ishiwata has got his head screwed on the right way around, so I left these alone as well.
I also had another "stab" at the PSU. Out came the two 470uF "Silmic" Capacitors in the Analog PSU (C803, C804) to be replaced with two 6,800uF 63Volt Units. I used what I had at hand (Panasonic TSU Series). I again placed a Bypass-cap across these, this time two red 0.22uF WIMA Cap's.
There are more Caps directly following the +/- 12 Volt Regulators (C805, C806). In these positions I can only recommend the largest possible Low-Z Capacitor you can lay Your hands on. Panasonic HFQ 6,800uF 25Volt will be dandy. I had to settle for Dubiler 2200uF 35Volt (low -Z 105degree). Another set of yellow 22nF Wima bypass Caps go in here as bypass.
Any more things to do? More magic parts to come. Some people recommend Schottky Diodes to be used in the Rectifiers. Does it work? Some people say no. They have measurements to prove it. Other say yes. I tried them and I say yes - they do make a (not subtle) difference. D801 - D804 where replaced with 1.1 Ampere 90 Volt Schottky Diodes. Across each of these Diodes I placed one of the 100nF (50V) ceramic Chip-Caps.
In the digital PSU's I used again Schottky Diodes (D811, D812) and placed Ceramic Chips across these. Ceramics also went across C813, C815. Also C871 was again replaced with a Nichicon PL Series 1,000uF 25Volt Capacitor with another ceramic bypass Cap.
The CD-67 Main-Board has positions for a Mains-line-filter, which are unused. These are located near the Mains-switch. Please be careful as you are working here with potentially lethal Voltages. Also, if you mess up here, a higher risk of fire may result.
Firstly, there are two unused solder-holes near the position of JH04 which can take the usual Mains-Filter Film-Capacitor (make sure to use one SPECIFIED for Mains-Filtering - this is dangerous territory).
Another position is provided for a common-mode Choke (LH01) which are bridged by U243, U245. Just put a suitable choke in. I used a mains-rated common-mode choke salvaged from a switched mode PSU Board, together with the Capacitors that where on there.
I also "found" a filtered IEC-Mains-inlet. Thus I mounted the IEC Inlet at the Back of the Player, so I can experiment with Mains-Leads in the Future. For the time being, I used a spare Kettle lead (large cross-section Leads).
Please do not use anything here that is not specifically designed and specified for mains-filtering at your local Voltages.
Now it is time for some subjective impressions. I did all the described MOD's in several steps. In the first round I really did the Bulk of the MOD's. I only had to omit the Schottky Diodes and Polystyrene Capacitors (I forgot to buy them).
The result was a more weighty, substantial Bass and more Detail in general. Quite pleasant, but some of the nasty characteristics remained. Putting in the Schottky Diodes and Polystyrene Cap's in the Filter cured not only the excessive sibilance of the Player but again helped to reveal more Detail and ambiance. Was it the down to the Schottky Diodes or the Polystyrene Cap's or do I hear things (I definitely do, actually!)? Who knows, I certainly don't.
However the Player was (in my opinion) still too bright and the "timing and pacing" (yes the very NAIM-ness of it) was not that good on faster track's. The third round of MOD's (the bigger analog PSU Cap's, analog LC Decoupling and the changes in the Filter) cured that rather nicely. The time-honoured recipe of beefing up the PSU Cap's helped in the timing department, while the small change in the Filter smoothed out the high-end. As added bonus, the Player now digs out Bass frequencies I never knew where on these recordings.
Note, that the second and third step of MOD's happens to be largely a fine-tuning exercise, changing specific parameters to achieve MY personally favoured Sound. You may actually like the Bass-performance of the Original Version better. You may also prefer the slight rise in the upper treble. The slight veiling of detail before the Schottky Diodes (yes I honestly think they are responsible - but I'm not going to take them out again to prove it) may be to your liking more than the "warts, dirty stuff and all" approach my unit now takes.
With the introduction of properly terminated Coax-Cables for all digital signal traces, the last trace of the "typical digital hardness" was gone. Completely! No more exaggeration of sibilants.
Let's face it. This CD-Player now does gets fairly close to the Master-Tape. It does not editorialise. It does not omit much. It adds very little of it's own. Ultimately resolution is limited if compared to my Turntable and specifically when re-creating the acoustics of the original room is concerned the Turntable is still ahead, though the Turntable just about draws with the CD-Player where Bass is concerned.
All in all, I feel that both Turntable and CD-Player do pass the parts of the music they pass through completely intact and with little editorialising!
So where do we go from here? Well few easy to do things remain. We can improve the Master-Clock further by adding a Tricord Clock 2 Board (a high precision X-Tal oscillator) or something similar.
We can build an external Power-Supply unit along the lines of a NAIM-Supercap meets Norman Tracy's X-Dac advanced Power.
Say two 330 Watt Toroidal Transformers (one 2 X 18 Volt AC and one 2 X 12 Volt AC) with 12,000uF (12 X 1,000uF Nichicon PL or panasonic FA Series) Filtering per Voltage and some Chokes and polypropylene Cap's thrown in for good measure with LM317/337 Pre-Regulators.
This would give us two separate "raw" 12Volt Voltages for the two 5Volt Supplies and the "raw" +/- 18 Volt Voltages for the +/- 12 Volt Supply. In this case the +/- 12 Volt regulators should be really replaced with Linear Technologies LT1033/1085.
We could also call it Black Gate or Os-Con Caps all around the analog Supplies and replace all resistors there with Vishay Bulk Foil Types. If you have a standard 63/7 or a 53/7, it may be worthwhile to buy all Black Gates or Os-Con's for the analog PSU's while while you do the MOD's.
In my (SE) Unit applying "waste not - want not" ended me up with Elna Silmic or Starget Capacitors all around the analog supplies and at the DAC's analog supply anyway.
You could possibly build a fully discrete Class A analog Stage (or even a valved one). It should be noted though, that the digital Output of the DAC necessitates high Order (at least 4th Order) reconstruction Filters and the differential Output also forces a fairly complex Circuit. Given that the Op-Amp's used work for the Impedance's used in Class A throughout and are about as good as solid state gets, gains again may be small.
Another last tweak would be the use of Blue Led's to light up the CD, for whatever that does. I had a look around the transport and could not see any simple way to accomplish this with a single LED (no place to put it). Thus we would need a "Flood-light" battery of Blue (or green) LED's to "bathe" the CD in this "magic" light. This approach may however give problems with the additional Current Consumption from all the LED's.
It apparently does make a difference though. Krell demo'd for a while a version of their integrated CD-Player which allowed the Bank of green LED's in the CD-well to be switched off. Those who witnessed these demonstrations are adamant that the LED's did indeed improve the Sound. Go figure.
The Cost of most of these undertakings is fairly substantial. All but the Black Gate / Vishay approach will require very substantial amendments to the Unit as well. You are of course free to go much further than I did.
However I personally feel that these additional MOD's go way beyond the Spirit of my original exercise, which was to stay within the Budget for a Marantz CD-63 KI-Signature (500 British Pound or 800 US Dollar) and to turn the CD-67 SE into something better. Given that the CD-67 SE lists at 350 British Pound (550 US Dollar), I think I stayed well within my Budget.
I managed to get away without too much major Surgery on the Unit. Really the only Telltale sign on my unit is the IEC-Mains Connector and the new RCA Jack's. Leave that one out of the list, and the unit remains almost entirely indistinguishable from a "stock" Unit (leaving the bypass cap's below the Board out of the picture and of course the Sound). Many people that are handy with their Tool-kit and Soldering Iron should be able to implement most or even all of these MOD's without too much difficulty.
Mission accomplished. As usual, Your milage may vary.
One last warning. During the last set of my MOD's something happened in the Anode-voltage switching of the Display, leaving the display off. Having the Service-manual (and some skills in fault-finding) allowed me to zero in on the problem quickly and fix it even without taking the Board out.
As for adapting all or any of these tweaks to other CD-Players, most can be adapted easily. I strongly suggest however to make sure to get the Service Manual and if possible the Design Reference Sheets for the Chip's used (I had them for all Chips in the CD-67).
© Copyright 1997 Thorsten Loesch - http://www.tnt-audio.com