Author Topic: CD Player (Read 176367 times)

rascal101 · « **Reply #1080 on:** Apr 07, 2006 at 09:34 AM »

You can have a good DAC but the CDP still sounds bad. After the D/A IC, you have an I-V converter, a filter and DC blocking caps. From experience, I-V converter and filter for most CDs and DVDs are pretty good however, it is the DC blocking caps I believe that mostly screws things up. For all the mods I performed this is the area where I see most improvement as such I am now concentrated only on this (90%) and the AC line filter (10%). Everything else I have ignored.

I believe most designers and manufacturers leave this one out so they can have segregated pricing and still maintain PCB layout and bill of materials. I think it is a good strategy on their part. In fact looking into the Sony CDPs I've owned the high end and low end have same D/A converter and practically same output circuit block only major difference is the DC blocking caps!

Inasmuch as I want to modify lots of components, I believe I cannot match company resources of these designers and manufacters. They practically have all the cards and most problems should have already been addressed.

Have also looked into the clock circuit and based on TNT audio and other people who have tested re-clockers the improvement is not significant enough to be heard by people without golden ears - eg me.

So based on my experience, to outperform this so called high end CDs you only need to focus on the DC blocking caps and improve AC line filtering (by differential choke and/or differential caps).

izukiultra · « **Reply #1081 on:** Apr 07, 2006 at 01:34 PM »

Quote from: rascal101 on Apr 07, 2006 at 09:34 AM

You can have a good DAC but the CDP still sounds bad. After the D/A IC, you have an I-V converter, a filter and DC blocking caps. From experience, I-V converter and filter for most CDs and DVDs are pretty good however, it is the DC blocking caps I believe that mostly screws things up. For all the mods I performed this is the area where I see most improvement as such I am now concentrated only on this (90%) and the AC line filter (10%). Everything else I have ignored.

I believe most designers and manufacturers leave this one out so they can have segregated pricing and still maintain PCB layout and bill of materials. I think it is a good strategy on their part. In fact looking into the Sony CDPs I've owned the high end and low end have same D/A converter and practically same output circuit block only major difference is the DC blocking caps!

Inasmuch as I want to modify lots of components, I believe I cannot match company resources of these designers and manufacters. They practically have all the cards and most problems should have already been addressed.

Have also looked into the clock circuit and based on TNT audio and other people who have tested re-clockers the improvement is not significant enough to be heard by people without golden ears - eg me.

So based on my experience, to outperform this so called high end CDs you only need to focus on the DC blocking caps and improve AC line filtering (by differential choke and/or differential caps).

Hi-end equipments sometimes very subjective. It's always depends on the ears of the beholder (not to mention how deep is his pockect). I've heared a lot of high-end as well as mid-end CD players you will never know the difference unless for an A-B comparison. THere are few people can tell whats the difference between the following CD players: Meridian; Elgar Ring; Mark levenson, Musical Fidelity etch. Sabi nga nilaif you can't hear difference between your DVD player and the above players mapalad ka.

DAC's; OP-Amp as well as the Clock of a CD player, plays a major role on how your player will sound. There are tweakable players but still their sonic capability is still limited. ask some audiophiles that spends $KK in their digital source but often back(appreciate) their record player

. Just me.

rascal101 · « **Reply #1082 on:** Apr 07, 2006 at 03:15 PM »

Quote

DAC's; OP-Amp as well as the Clock of a CD player, plays a major role on how your player will sound. There are tweakable players but still their sonic capability is still limited. ask some audiophiles that spends $KK in their digital source but often back(appreciate) their record player . Just me.

Understand this but don't you think the engineers or designers are not doing their job? Most manufacturers test their products electrically and acoustically. So I don't quite understand how can we be better than them. They have more equipment (anechoic chambers etc etc), resource persons to test their designs and definitely more money. How do we stack up against these odds?

I have done extensive work on this but my lower end CDP beat a higher end CDP with better DAC, clock circuit and Op-amps. With the same output DC blocking circuit the higher end CDP equalled my low end CDP. The I-V and filter circuits are standard circuit blocks. I believe manufacturers and designers already know this.

Weng! · « **Reply #1083 on:** Apr 07, 2006 at 05:06 PM »

Quote from: rascal101 on Apr 07, 2006 at 09:34 AM

So based on my experience, to outperform this so called high end CDs you only need to focus on the DC blocking caps and improve AC line filtering (by differential choke and/or differential caps).

sir rascal,

how did u tweak the dc blocking cap part? i have read one tweak about the sony playstation 1 (for audio) is to by-pass/remove the dc blocking cap (that connects to the rca out) after the DAC.

click here to read the mod's details

rascal101 · « **Reply #1084 on:** Apr 07, 2006 at 07:05 PM »

I based on the work from Walt Jung. Here's the link

http://pinoydvd.com/board/index.php?topic=43433.0

Bogsle · « **Reply #1085 on:** Apr 21, 2006 at 04:03 AM »

Quote from: rascal101 on Apr 07, 2006 at 03:15 PM

Understand this but don't you think the engineers or designers are not doing their job? Most manufacturers test their products electrically and acoustically. So I don't quite understand how can we be better than them. They have more equipment (anechoic chambers etc etc), resource persons to test their designs and definitely more money. How do we stack up against these odds?

I have done extensive work on this but my lower end CDP beat a higher end CDP with better DAC, clock circuit and Op-amps. With the same output DC blocking circuit the higher end CDP equalled my low end CDP. The I-V and filter circuits are standard circuit blocks. I believe manufacturers and designers already know this.

Tanong bro.

Di kaya yung cost of working on the lower end CDP would have already bought you a much higher end CDP? Not to mention the time and effort put into it.

Bogsle · « **Reply #1086 on:** Apr 21, 2006 at 04:17 AM »

Quote from: rascal101 on Apr 07, 2006 at 09:34 AM

You can have a good DAC but the CDP still sounds bad. After the D/A IC, you have an I-V converter, a filter and DC blocking caps. From experience, I-V converter and filter for most CDs and DVDs are pretty good however, it is the DC blocking caps I believe that mostly screws things up. For all the mods I performed this is the area where I see most improvement as such I am now concentrated only on this (90%) and the AC line filter (10%). Everything else I have ignored.

I believe most designers and manufacturers leave this one out so they can have segregated pricing and still maintain PCB layout and bill of materials. I think it is a good strategy on their part. In fact looking into the Sony CDPs I've owned the high end and low end have same D/A converter and practically same output circuit block only major difference is the DC blocking caps!

Inasmuch as I want to modify lots of components, I believe I cannot match company resources of these designers and manufacters. They practically have all the cards and most problems should have already been addressed.

Have also looked into the clock circuit and based on TNT audio and other people who have tested re-clockers the improvement is not significant enough to be heard by people without golden ears - eg me.

So based on my experience, to outperform this so called high end CDs you only need to focus on the DC blocking caps and improve AC line filtering (by differential choke and/or differential caps).

Tanong bro.

So by putting in the CDP a well known DAC like Burr-Brown's puts bias on the choice of product by consumers, but does not necessarily mean the product is superior in playing music. We're being misled!

So next time, when buying a CDP we should identify the DC blocking caps being used and refer to it instead of the old habit of knowing the DAC, whether its Burr-Brown, Wolfson, etc. Hmmm, is this so?

odyopayl · « **Reply #1087 on:** Apr 21, 2006 at 08:44 AM »

So next time, when buying a CDP we should identify the DC blocking caps being used and refer to it instead of the old habit of knowing the DAC, whether its Burr-Brown, Wolfson, etc. Hmmm, is this so?

rascal101 · « **Reply #1088 on:** Apr 25, 2006 at 11:32 AM »

When in doubt, test.

Suggest you perform testing to refute above statements. Also suggest that you get a copy of the Linear Design Seminar from Analog Devices. Hope you are not using the internet or word of mouth as your primary means to get information.

rascal101 · « **Reply #1089 on:** Apr 25, 2006 at 11:57 AM »

Quote from: odyopayl on Apr 21, 2006 at 08:44 AM

So next time, when buying a CDP we should identify the DC blocking caps being used and refer to it instead of the old habit of knowing the DAC, whether its Burr-Brown, Wolfson, etc. Hmmm, is this so?

Burr-brown has been bought by TI.

Garp · « **Reply #1090 on:** Apr 25, 2006 at 01:24 PM »

Improving power filtering and upgrading the coupling caps in CD players have long been a staple of DIY electronics. This guy asserts the choice of DAC also matters: (http://www.fortunecity.com/rivendell/xentar/1179/theory/vasfda/vasfda.html).

But I'm not one who can verify if this is true or not since I'm no techie. According to TL, among other factors that make some DACS superior than others, is that a lot of DACs now incorporate an analog stage into the chip, which according to TL were mostly poorly implemented.

Garp · « **Reply #1091 on:** Apr 25, 2006 at 01:31 PM »

Quote from: rascal101 on Apr 07, 2006 at 03:15 PM

Understand this but don't you think the engineers or designers are not doing their job? Most manufacturers test their products electrically and acoustically. So I don't quite understand how can we be better than them. They have more equipment (anechoic chambers etc etc), resource persons to test their designs and definitely more money. How do we stack up against these odds?

Possible reasons: cost considerations, product positioning, pricing strategy. It's often been asked, why use an electrolytic for that DC blocking cap--surely the manufacturer could have spent a little more and charged a little more to have that replaced with a film capacitor?

Garp · « **Reply #1092 on:** Apr 25, 2006 at 01:40 PM »

In terms of I/V conversion---I have yet to come across an opinion that active I/V conversion via opamps is superior to simple I/V conversion via a bunch of resistors. Of course, it doesn't confirm that passive I/V conversion is universally superior, but its easier for me to accept--intuitively that is--because of the simplicity of passive over active I/V conversion.

rascal101 · « **Reply #1093 on:** Apr 25, 2006 at 01:44 PM »

Sir Odyopayl,

To understand how well a circuit sounds or performs means taking (in this case a CD) apart. Ganda iyung DAC pero pangit iyung mga caps dun sa signal path - wala rin. Tama circuit pero paikot-ikot layout - wala rin! Good sound means correct circuit and correct layout. In the circuit aspect alone, halos wala ng innovation specially in CD players. So, why follow conventional logic ... palit palit piyesa. You need to go one step further and understand how to get the most bang for the buck ...

Take this, alam mo ba na iyung higher order filters of most CDPs today do not filter out properly 20KHz signals and up. Why, because a brick wall filter does not have a 90degree slope that's why. Sa textbook lang iyun. Pero it does its job because most of the unwanted noise is filtered out - or does it?

I can't overemphasize layout ...

What you and I do not see is how manufacturers layout their PCBs. Alam mo ba na kung may konting mali sa layout malaki na effect electrically. Iyung lang umangat ng konti iyung piyesa puwede na bumagsak sa EMI! Iyung lang humaba iyung loop area dun sa amp section pumapangit na gain/phase response and tumataas noise.

rascal101 · « **Reply #1094 on:** Apr 25, 2006 at 01:49 PM »

Quote from: Garp on Apr 25, 2006 at 01:40 PM

In terms of I/V conversion---I have yet to come across an opinion that active I/V conversion via opamps is superior to simple I/V conversion via a bunch of resistors. Of course, it doesn't confirm that passive I/V conversion is universally superior, but its easier for me to accept--intuitively that is--because of the simplicity of passive over active I/V conversion.

Tama ka Sir Garp. Most current sensing circuits today uses precision resistors. In fact, puwede siguro gumamit ng hecnum wire. Check ko muna ...

s2kov · « **Reply #1095 on:** Apr 25, 2006 at 02:15 PM »

pabor ako dyan!

Quote from: rascal101 on Apr 25, 2006 at 01:44 PM

Sir Odyopayl,

What you and I do not see is how manufacturers layout their PCBs. Alam mo ba na kung may konting mali sa layout malaki na effect electrically. Iyung lang umangat ng konti iyung piyesa puwede na bumagsak sa EMI! Iyung lang humaba iyung loop area dun sa amp section pumapangit na gain/phase response and tumataas noise.

odyopayl · « **Reply #1096 on:** Apr 25, 2006 at 02:42 PM »

What you and I do not see is how manufacturers layout their PCBs. Alam mo ba na kung may konting mali sa layout malaki na effect electrically. Iyung lang umangat ng konti iyung piyesa puwede na bumagsak sa EMI! Iyung lang humaba iyung loop area dun sa amp section pumapangit na gain/phase response and tumataas noise.

==============================================================================
Yup, I agree. This is part of our Job in Reliability & Failure analysis

'Yung umagat na piyesa" we call it tombstone (SMD terminology)
Things now becomes complicated with respect to PCB making. There are 2-15 layers or maybe more is already available in the market.
Lets make things complicated. What can you say about the sonic difference between Surface Mount Device as compared to Thru Hole Technology. Electronic part are now getting smaller, some are using "bare Die" using flipchip technology.

rascal101 · « **Reply #1097 on:** Apr 25, 2006 at 03:02 PM »

Mas pabor sa akin ang maliit na piyesa. Mas maliit loop areas. I would however limit the use of SMDs to control or drive circuits specially for passive components. Ok lang for semiconductors.

rascal101 · « **Reply #1098 on:** Apr 25, 2006 at 03:09 PM »

Quote

Yup, I agree. This is part of our Job in Reliability & Failure analysis

Sir anong company po kayo. Test/Product engineer kasi ako dati ng converters at op-amps dun sa Analog Devices.

rascal101 · « **Reply #1099 on:** Apr 26, 2006 at 09:48 AM »

Sir Garp, Odyopayl,

Maganda rin i-mod iyung I/V converter at voltage reference nung DAC. Kung titignan natin, itong mga circuit at piyesa ay napakahalaga dahil kung may inaccuracy iyung I/V converter eh di mali iyung output signal papunta sa op-amp o amplifying device. Tapos kung hindi accurate iyung voltage reference nung DAC eh di mali di ang pag convert from digital to analog.

Halimbawa, kung may ginagamit tayo na voltage reference na 2.5V at ang accuracy niya ay 1% over commercial temp range, ibig sabihin puwedeng lumihis siya ng +/-25mV. Ibig sabihin iyung voltage reference pala naglalaro from 2.475 to 2.525V! Eh kung 16bit iyung converter with 38.1uV resolution, palpak na palpak pala iyung reference. Dapat at least kalati man lang ang accuracy niya sa 38.1uV or with +/-19uV ang upper at lower limit. No wonder, kahit sangkatutak mod natin kulang pa rin kung di natin inaayos voltage reference. Dagdagan pa nung I/V conversion process ...

Kung hindi man kaya iyung ganitong resolution at least pumili ng < 0.05% accuracy. Mas mabuti na ito kesa sa 1%. Ano kaya gamit ng CDP ko?

rascal101 · « **Reply #1100 on:** Apr 26, 2006 at 04:14 PM »

My CDP uses a D/A converter with an internal voltage reference :'(

av_phile1 · « **Reply #1101 on:** Apr 27, 2006 at 01:27 PM »

Just curious if all these conversions are necessary when you use S/PDIF connection to your receiver. And knowing that the receiver will just convert your analog signals into digital before they even reach the volume controls, why use the analog out of a digital player

TIA

rascal101 · « **Reply #1102 on:** Apr 27, 2006 at 01:36 PM »

Do you have a typical block diagram for a receiver? I'm getting confused ... The receiver is capable of receiving analog and digital signals right? If the signal is analog, then it goes to a A/D, DSP then D/A right? If its digital then DSP and then D/A right?

av_phile1 · « **Reply #1103 on:** Apr 27, 2006 at 02:20 PM »

Typical of most receivers is to convert all analog input signals to digital, thus, D/A. If you use the digital input, then no D/A conversion is done, and all the signals are now merrily in the digital domain until they get pass the DAC.

But that's not the point of my question. I was asking if the conversions being discussed to alter the characteristics of the player's after-DAC analog stages would matter if you used the digital out. And even if you've achieved a perfect analog signal out of the digital player, by tweaking the digital clock, I/V conversion, the op amp chips, the voltage reference, etc, what benefit would that do when the receiver just converts it back to digital when playing through a typical receiver? Wouldn't you be back to square one? Now for you to restore the perfect analog signal you got from a tweaked CD player, wouldn't you have to do the same tweaks to the receiver's DAC and associated circuits?

rascal101 · « **Reply #1104 on:** Apr 27, 2006 at 02:37 PM »

Conversion to digital is A/D or ADC - analog to digital converter.

If you used the digital out of your CDP to the receiver, the analog stage of the CDP is useless.

Yes I'm afraid you need to mod your receiver too.

av_phile1 · « **Reply #1105 on:** Apr 27, 2006 at 03:03 PM »

oops, right, A/D, got me confused there. Thanks.

As I suspected. So do you guys modify the receiver DACs and associated DAC circuits as well?

rascal101 · « **Reply #1106 on:** Apr 27, 2006 at 03:16 PM »

I used to do it but changed tack. It voids warrantys and makes the CDP or DVD look bad. I have never touched the inside of a CDP or DVD since then. Nowadays all mods I do are external. Can't discuss it though

av_phile1 · « **Reply #1107 on:** Apr 27, 2006 at 05:27 PM »

Modifying does entail risk. Personally, since i'm using a digital source anyway, I prefer to go the digital route all the way from source to the DAC before it finally goes to the power amps. Modifying the player DAC and associated circuits can improve the sound but only if you feed that to an analog device like a tube or plain stereo integrated so you can hear the fruits of your labor. Otherwise, why bother. A receiver will just nullify all that labor when it converts the analog input to digital and back again right bfore the amp. The conversion from digital to analog out of the player and then from analog to digital when it reaches the receiver, then back to analog to feed the power amps seems like you get so many conversion losses along the way. At least in going digital all the way, there's only one D/A conversion taking place which is right before the power amp. The inescapable fact is that there will always be signal or data losses in any transciption from analog to digital and vice versa, or from any transciption from one format to another.

Dracula · « **Reply #1108 on:** Apr 27, 2006 at 06:02 PM »

I am using a marantz cd6000, when I was in the UK I was toying with the idea of getting it modified by Heart (i.e. add tubes and other stuff) but was very expensive...the tweak would end up more expensive than the player...

rascal101 · « **Reply #1109 on:** May 01, 2006 at 03:05 AM »

The mods IMHO if just change parts to better one would be limited to very subtle improvements. After going through 2 CDP and 1 DVD mod, I don't think it's even worth it - even after modding the analog amp section and PSU section with a new circuit.

I have realized that you really need to get your hands dirty with some measurements first specially noise with a fairly good oscilloscope. You need to check from about 100Hz to 200KHz by varying the varing the time settings and see what kind of noise is present. Attack these noise issues with a filter circuit.