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Here is the Essay on Digital Mods

Modifying Digital Players – the pros, cons and pitfalls

This essay has resulted from a post I put up on the Digital Board of Audio Asylum some time ago. It received some input from modders which I took back to Leon Gross of Soundlabs Group for comment. Thanks for that Leon. The following is an integration of all the ideas put forward with quotes from others in italics. Modifying components is not something to undertaken lightly as it is expensive and can disqualify a manufacturer’s guarantee, so the more known about the pros & cons the better, so I hope this essay helps clarify what is involved.

First up there is some debate about whether or not modification is necessary on the more modern players or if it is economically sensible on older players. I guess there can be no definitive answer to this as players, both old and new, vary so much in their circuitry and in the components used. It is for this reason that the commercial press cannot endorse modifications and nothing will be read about it beyond the internet forums and a few audiophile publications for the very good reason that not all modifications are the same, and what applies to component A may not be suitable for component B. This is discussed in more detail later.

However my personal experience is that no player is perfect and all that I have owned have benefited from modification by James at Soundlabs Group. A prime example of that is my Meridian 800 player, one very highly regarded by Stereophile and The Absolute Sound. James modded it and Leon commented that “Even the Meridian has a very simple clock system in comparison (to the modified unit)”. The improvement in bass after the Meridian mod was obvious. Due to a time lapse I cannot justifiably comment on whether or not there was dramatic improvement elsewhere but the bottom line is the CDs sound better to these ears than vinyl via an expensive Koetsu Oynx Platinum cartridge.

Modifying components is something many are loathe to do, reasoning that if something could be improved then the manufacturer would have done it. Unfortunately I feel this reasoning is faulty on two counts –

1. Improving jitter (concerns the timing of those digital bits – see a simple definition & links at the end of this essay for further information on the topic) means more expensive clock modules -> higher cost -> less competitive

2. Most people they are selling the gear to would not notice any difference in sound.

The second count has remained unchallenged but the stated improvement to jitter has been challenged. One comment from an audiophile was “jitter actually softens the sound, makes it fuzzy - indistict, but usually pleasant”, something I cannot agree with, nor does Leon with his remarks “Pleasant is usually a personal preference, basically saying that the distortion is a nice type. There is no problem with this, it is a personal preference, but reducing jitter makes the sound more accurate than it was, something that most people are trying to achieve. Everybody knows that high-end systems really show what is recorded on the CD and reducing the jitter will increase that resolution. If you don't like what you hear, then that is more a result of the source material.”

Some people also claim that competent design can make conventional clock circuits equal or better those provided by external clock generators and that with no material increase in cost. Against that argument, although a better clock could be incorporated at the manufacturing stage for much less than fitting one after, the usual saying of 50 cents at manufacturing = $50- at retail probably applies. Thus, in a very competitive environment, manufacturers cut corners by using cheaper parts. Note that the clocks used by Soundlabs Group and others are not “external clock generators” as they are fitted into the existing circuit although external fitment is feasible at the expense of longer, undesirable cables.

DIY is an approach some have attempted but with varying results. Leon comments that “a lot of people have bought un-branded & kit clocks and been burnt by them. There is no local support and we know of several people who have damaged their CD Players, we have even fixed one for a customer. Some of these clocks are quite old technology now, actually a copy of an early LC Audio clock. So if judgments are being made on old technology compared to the latest, it is misguided. The latest clock from both Audiocom and LC Audio are cutting edge designs. For example the LC Audio clock is on a four layer PCB with 4 power supplies and 91 active components. The new XO3 has both a stand-by feature to turn it off plus has 5V or 3.3V selectable.”

No doubt Leon has a different viewpoint to DIY audiophiles but, IMO modification is a job best done by the experts unless you really know the ins and outs of the gear under consideration. In support of this, another comment on the original article on AA from a modder was “In reference to internally installed clock modules, in many cases it is difficult to install them without lousing up the ground routing. Competent and experienced technicians will likely know how NOT to do it, however I have seen enough cases where clock modules had been fitted in a manner that would not reduce jitter.”

A further comment from another modder illustrates the pitfalls of modification: “A lot of mod companies and people are putting in aftermarket clocks without even considering the voltage levels of the output. For example, an LClock X02 outputs a 5V clock signal. Mod company web pages that mod players (especially dvd/cd players and sacd players) don't mention or may not consider that the chips that these clocks drive run off of 3.3V, 2.5V, and even 1.8V clocks these days. They were never specified to run off of 5V. Before just slapping in an aftermarket clock, you really need to know how it is going to work with the chip in question. Also, do those who use external power supplies for their clocks wire in an ON/OFF circuit to turn off the clock when the chip is turned off? If not, the clock is always on feeding into a chip that is supposed to be off. This may not be a good thing either. And what turns off first, the clock or the IC it is driving?”

Now I claim that the one fundamental change for digital gear is a better timing clock but that MUST have the correct frequency or everything will be screwed up. However not everyone agrees that a better timing clock is the first best move. Another viewpoint is that cleaning up the supply to the existing clock and eliminating possible poor ground routing can be as effective and should be tackled first. Leon agrees that improvement to power supplies is a good move as are other mods like putting Blu-Tac or hot glue over the crystal, but these improvements will be nowhere near like what a proper clock will do. Obviously there are a lot of changes which can be made and how far to go is often dependent on the budget, or in the case of DIY, how thoroughly the circuit is understood.

Another comment on this issue of the timing clock being fundamental from a modder was: “IMO, there are a lot of other things that contribute to harsh, undesireable CD sound besides jitter. Power supply design (linear, switch-mode power supplies, separating analog and digital sections, noise filtering, etc), analog output stage design (opamp vs discrete transistors or even tubes, biasing, muting transistors, etc), digital and analog filter design, vibration control, noise control, data buffering, etc. When modding a cd or dvd player, I look into more areas than jitter and I know the modders out there who advertise do the same. Modding can entirely change the sound of a player, but also involves modding for system synergy, or MFSS :) I believe adding in all these other areas of modding to your document will enrich its content.”

On the above para , Leon commented: I agree. The reason we tend to recommend the clock first is that it is the most cost effective upgrade. Changing the diodes and caps sure do make a difference but not as much as the clock does for the time and money spent. We recommend first the clock, then the output stage, then the power supply. I agree that the mods can change the sound of the unit but this is generally only when the output stage is modded as it has a direct bearing on the tonal qualities. The digital side wont change the tone, rather the staging, clarity etc. (I guess you could say that is the tone but I don't!)]

From what I read, changing the clock is the mod performed most so seems the most sensible starting point with all the other tweaks desirable back up improvements. However one modder suggested that “The majority of components are in the PSU and a simple classic oscillator (including certain "can" types) can provide substantially equal jitter performance, if the PSU is competently implemented.” However Leon disagrees with this: “Even most high precision crystals have only 5ppm accuracy and have most cases sine wave outputs. The XO3 has much more of a square wave and has a stability of 1ppm at normal operating temperatures. of course the PSU is important, but that is not the whole story.”

I feel that music from digital sources, both hardware & software, has improved dramatically in the last few years and CDs need no longer sound harsh and edgy if those digits are handled deftly. However this opinion was challenged by the comment from a modder -

“ Actually, digital technology on the replay side has shown few observable improvements over the mid to late 1980's level of the "state of the art". However, be aware that the electrolytic capacitors in all equipment degrate substantially with time and usually should be replaced after 4 - 6 Years. Thus comparing a several year old SOTA piece of gear against a new, burned in unit will usually show the new unit to be superior, not because of any inherent quality in the "new" unit, but simply because the older unit no longer functions to original specification. A complete re-build usually gives drastic improvements on older units. In most older (and modern) Players one finds NE5532 style Op-Amp's, these too can be improved upon drastically.

Leon comments “that there has been little change in CD Players over the years with the design basically the same. However I feel that what has changed is the quality of components (in most cases). This is exactly why the mods work, because they are leading in development, for example the ZAPfilter is a miniature class A amp for the output stage. Virtually all CD Players still use op-amps, same design they use 15 years ago.
I use often an example with jitter likening it to a camera. All the information is there but the picture is a bit blurry. Putting in a clock will sharpen that image, like focussing the lens... It does not change the tone of the sound as the tone is determined in the analog stage from the DAC onwards.
We have never had any problems with ground loops. We connect the clock signal ground to the same point the original clock was connected. The jitter is low right at the start. Every extra part the digital signal goes through will increase jitter. I think "Sayonara" was referring to relocking units which go after the digital output, outside the machine. These have been tested by some magazines overseas and can in some case increase jitter if already at a low level. (They can also help.) Our clocks cannot increase jitter since they are at the very beginning, a solution that fixes the problem at the source rather than a band-aid approach after the problem has occurred.
I do agree that many newer units use poor quality parts, often a result of the manufacturers trying to cram as many functions / features into the parts as possible. This makes it cheaper for the manufacturer to build the unit but can have a resulting downgrading in the sound. We have modded many units with just a clock and never in four years has anyone come back and complained. We offer a money back guarantee if they don't like the improvement and never has anyone taken it up. 100's have been sold here.”

Another comment on the newer players from a modder was “they have integrated filter/DAC chips which are really inferior to the earier chips, also, many people - myself included, find the current crop of 24 bit chips inferior sounding to the earlier Burr-Brown 20 bit ones. My guess is a modest, hard sounding player got a few tweaks, one of which smoothed it out, very unlikely the clock - more likely a cap.”

Just exactly what modifications are best for any player seems to be contentious. Soundlabs Group argue that a new clock is the most effective change and, my experience with the Marantz CC4300 changer (see below), backs this up. However there are other viewpoints from different modders:

“There are many things that are applicable in terms of modifications and not all of those that have a large impact are electronic either. I think competent modifications should be viewed as a "package" and seen as such and not comprise a few expensive overhyped "modules" without actually addressing fundamental issues. Considering however the ease of fitting a "clock" and the relative profit margins on a clock module, compared to swapping out dozens of diodes and dozens of capacitors which are all "penny parts" and all together cost a lot less than a clock module, even after outrageous profit margins but take a lot of time we can place the comment in context. I find in most cases the analog stages to be the best starting point, followed by power supply line cleanup. This done correctly can give much larger improvements than just fitting a new clock.
No doubt a discrete analogue stage and a clean clock are a "good thing", yet if the DAC supply lines remain noisy and the DAC itself is of poor quality and the player suffers from substantial dissonant mechanical resonances, what is the benefit of adding these items?
In forums like these one sees regularly people asking "Should I add a clock (or analog stage) to Brand X, type Z player and will it make it better than the best out there?". Well, rather too often the answer should be "don't bother, get a better platform to mod".
Just for fun, a really well sorted Marantz CD-63/67 can still take on most of the digital gear out there and pull level, without requiring expensive clock and analog modules, simply by using suitable techniques to eliminate fundamental design flaws, which the fitting of a Clock and Analogue Stage module would leave entirely alone and still in place. I am not against modifications, but I would prefer if things would be placed in the correct context and not be over hyped.”
I suspect many have wasted heaps of money on buying new speakers, amps, interconnects etc or go to tube amps, all in an effort to tame that digital sound and make it listenable. But this could be tackling the problem from the wrong end and could be masking the effects of poor digital to analog conversion rather than improving the overall sound. The biggest culprit is the CD player – timing and other errors reading those bits and converting them to analog sound. Those timing etc errors are inconsequential in reading computer CD ROMs but timing accuracy is vital to produce fine sounding music. If the signal going in at the start of your audio chain is bad, you might be able to mask it, but you can never improve on it.

The newer players are much improved on earlier efforts in some areas but not others as the earlier discussion shows, but purchase of a newer one might not be the best path to take. Modification of the present player might give better results than buying something new. Whether or not a certain player or component is an economic proposition to modify is beyond the scope of this article and is best answered by either experienced owners or by James or Leon at Soundlabs Group.

Sadly, it seems that the relatively poor jitter control also extends to new high end players. The latest SACD & DVD-A players benefit from modifications which can also improve the video output on those which cater for DVDs. However I also suggest caution with attempting to expect great results from modifying “el cheapo” units. The most expensive players are not necessarily the best to work upon but there is a lower limit on what is worthwhile operating on. Note that the Marantz CC4300 changer I had modified is not the cheapest changer available and has a good reputation even before modification, so it is this type of unit which gives the best results.

My initial skepticism about modification was overcome in 2003 and, as I have reported earlier, I have had all digital players (including laserdisc units) modified. The improvement in the sound of the music is not small. This was all driven home to me when I replayed the very first CD purchased. Good music, but it had been nailed as being a bit “edgy” and suffering from a degree of shrillness – a common malady of digititis. But no more. It is far cleaner and more musical than I ever could have imagined possible.

Here is what has been done to players here by Sound Labs Group in Melbourne and I cannot praise their efforts too highly :

All players were wired with 1 ACS-SW-0.5-S Silver Wire 0.5mm with 1 ACS-CS-2-S Cotton Sleeve 2mm and had deadening sheets fitted

Meridian 800 CD/DVD/DVD-A player (Only gives digital out – the DAC is a Meridian 861) -
1 Supply BlackGate Capacitors for Digital Output, DSP, DVD Controller, DVD Decoder and Video Encoder Modules.
1 AC-SCk PSU-S Audiocom Superclock PSU
1 LClock XO2 LClock XO2 27.0000MHz Kit

Pioneer HLD-X9 laserdisc player -
1 Supply 122VA Transformer 240/2x12.5+2x2.5+2x7.5
1 Supply 58VA Transformer 240/2x11.5
1 BDE-DIG 1-S BDE-Digital Output Kit DIG 1
1 LClock XO2 16M LClock XO2 16.9344MHz

Pioneer CLD-D925 laserdisc player -
1 LClock XO2 16.9 LClock XO2 16.9344MHz with PSU
1 LClock XO2 PSU LClock XO2 Power Supply Unit
1 BDE-DIG 1-S BDE-Digital Output Kit DIG 1

Rotel RCD-865BX CDP (modified up to analog out via the LC-ZAP filter but an external DAC proved to be superior) -
1 LClock XO2 LClock XO2 11.2896MHz Kit
1 LC-ZAPfilter2-S LC ZAPfilter Mk2 with PSU
14 Di-HSSR-4/600 Diode 4A 600V (TO-251)

Marantz CC4300 CD Changer (only modified up to digital out) –
Audiocom Superclock II with matching power supply
BDE digital output (DIG1)

Marantz SA-17S1 SACD Player (expensive due to Black Gate Caps on the 6 analog outs) –
1 AC-SC2-33-S Audiocom Super Clock2 33.8688M
1 AC-SC-PSU-S Audiocom Super Clock PSU
1 Supply Black Gate Capaciters for
24 Di-HSSR-4/600 Diode 4A 600V (TO-251)
1 BDE-DIG1-S BDE-Digital Output Kit DIG 1

Denon 3000 CDP-
• 1 AC-AC-SC2-16-S Audiocom Super Clock 2 16.9344M
• 1 BDE-Digital Output Kit DIG 1
• 1 BB-Small Silver Bybee Quantum Purifier Silver
• Mods to the power supply: 4 of Di-15A/600V HSSR diodes, 1 of 1000uF 16V STD Blackgate Cap, 2 of BG-STD 47uF/100V Black Gate Caps, 2 of 47uF/16V FK Blackgate Caps, 2 of AU-O 0.15uF/450V Auricaps, 1 90VA Torroidal transformer, 2 BB-Small SQP Bybee Quantum Purifiers SS
• Silver solder used + a quality RCA socket for digital out


Yes, the above modifications were expensive for both parts and labour but, IMO, the dollars were better spent there than chasing after other system changes following on the garbage in -> garbage out mantra.
Note I’m not claiming reduced jitter in a player will mean all CDs sound astoundingly good. Some are so badly engineered they are beyond redemption and, as discussed earlier, other modifications are also beneficial. But a lot more of the CDs are better than had ever been imagined possible and, IMO, the rotten reputation CDs have in many quarters is more a reflection of the playback equipment than the digital process, flawed as that sometines was early in the peace.

As you can see from this essay, exactly what to modify can be contentious. Different modders have different opinions and approaches. My only experience is with Soundlabs Group and I am very happy with what they have done on the gear here. They adopt a cautious approach and approach each component differently. A final comment from Leon on the subject: “We find more worth in upgrading power supplies (caps, diodes etc) if the unit is being used as a player (that is using the unit's DAC and output stage) as opposed to just a transport. Of course transports will improve with better power supplies but not to the same extent as a proper player. Also, from a business side, we have been doing the clocks and modules much longer than individual parts, so many earlier units we have modded we didn't even suggest caps or diodes etc since we didn't have source of good quality parts. Of course this has now changed!”

THE LINKS TO MODDERS:
• Australia: Soundlabs Group - Sydney, Leon Gross while in Melbourne, James Chen. http://www.soundlabsgroup.com.au/
• Alex Peychev http://www.aplhifi.com
• Allen Wright http://www.vacuumstate.com
• Audio Crafters Guild http://www.audiocraftersguild.com/acg.htm
• Dan Wright http://www.modwright.com
• Exemplar – John Tucker http://www.exemplaraudio.com
• Kyle Takenaga http://www.referenceaudiomods.com
• Matthew Anker http://www.sacdmods.com/
• Steve Nugent @ Empirical Audio http://www.empiricalaudio.com
• Richard Kern http://www.audiomod.com/pages/679746/index.htm
• Ric Schultz http://www.tweakaudio.com
• Parts Connexxion http://www.partsconnexion.com
• Musical Concepts http://www.musicalconcepts.com/mus_con.htm
* Tube Research Labs - www.tuberesearchlabs.com

Suppliers & other links :
Audiocom http://www.audiocominternational.com/
TNT CD player tests & reviews http://www.tnt-audio.com/sorgenti/sources.html
DIYHHiFiSupply http://www.diyhifisupply.com
Tricord Research http://www.trichordresearch.com

Simple definition of jitter:
1) In voice over IP (VoIP), jitter is the variation in the time between packets arriving, caused by network congestion, timing drift, or route changes. A jitter buffer can be used to handle jitter.
2) Jitter is the deviation in or displacement of some aspect of the pulses in a high-frequency digital signal. As the name suggests, jitter can be thought of as shaky pulses. The deviation can be in terms of amplitude, phase timing, or the width of the signal pulse. Another definition is that it is "the period frequency displacement of the signal from its ideal location." Among the causes of jitter are electromagnetic interference (EMI) and crosstalk with other signals. Jitter can cause a display monitor to flicker; affect the ability of the processor in a personal computer to perform as intended; introduce clicks or other undesired effects in audio signals, and loss of transmitted data between network devices. The amount of allowable jitter depends greatly on the application.

Jitter site:
http://www.jitter.de/

More articles on the subject:
http://www.geocities.com/jonrisch/cd-sand.htm Note that this article is particularly good and there is a link there for further discussion by Jon.
http://www.enjoythemusic.com/magazine/manufacture/1104/

Technical article on jitter:
http://users.rcn.com/wpacino/jitwtutr/jitwtutr.htm

Note that a Google search will yield heaps more net info on this topic.

Interesting times

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