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Old 27th October 2004, 11:23 AM   #1
Mosez is offline Mosez  Netherlands
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Default Mod/upgrade NAD C 541i

Haven't posted in these fora before, so let me introduce me on the fly.

I'm a project manager with a chemical and IT background, and some basic knowledge about DIY-electronics (I'm capable of soldering passive components without frying them too much).

So far I've been living quite happily in the Netherlands, but plan on moving (emigrating is a better word) to the US early spring 2005.

I own a NAD C 541i CD-player that I'm quite content with and plan on bringing too. From what I learned from the support manual, modifying the player to 110 Volts is pretty straightforward since the trafo and board are prepared for this (cutting a bridge and making another).

Now I figured that, while I'm in there, I might as well do some tweaking (clock, DAC, caps?). The 541i has a Burr-Brown 24 Bit Sigma Delta DAC (PCM1732).

Here is where I would like some advice/guidance. What would be relatively simple and cost-effective upgrades? I think I would be able to build a simple DAC for instance, but except a DMM I have no equipment to do measurements (like a scope, although I wouldn't know what I would be looking for anyway). Thanks in advance.

BTW: support manual (1.5 MB PDF) available on request
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Old 28th October 2004, 09:12 AM   #2
janusz is offline janusz  Australia
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Default NAD C541i modification

Hi Mosez,

I have a NAD C541i too and one day I'll likely do some modifications to it. As I have never ever done any mods to a CD player it will be my first and it will be later rather than sooner. At the moment I am collecting parts for the Stochino Amp and plan to built the first two units by the end of January so I'll be very busy until then and afterwards I have even a bigger project on my mind and afterwards another two Stochino units so I don't think I'll open the NAD earlier than in the late 2006. Si it looks that I will be using your experience in this venture.

Anyway, from what I know on the subject two kinds of improvements may be done to this and many other players in order to get better sound. Firstly a high quality XO clock could be installed (see LC audio or soundlabs for it). They sell such clocks with or without dedicated PS.

Secondly, one may upgrade caps, ICs and resistors in the analog section and PS. That is a relatively easy task. NAD C 542 is such a factory upgrade to the older C 541i so it might be of some help if you could get a service manual for C542 although it is not essential - the service manual for C541i is.

Apart from the above you can change everything but then I would start with getting a much better drive with lasers etc and a new case to fit it all. One would need a nice workshop with all the electronic equipement (mini factory?) to do that well. Anyway go to the LC audio site to read what could be done to a typical CD player.

Cheers,
Janusz

PS I would appreciate if you could email me a copy of the C541i player. That would save me some trouble in the future. My email is: janusz.pradzynski@dpi.wa.gov.au

How is life in Holland? I used to work in Rotterdam long time ago.
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Old 28th October 2004, 09:18 AM   #3
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Replacing op amps in an analogue stage is very popular upgrade, but to gain a quantum leap you would need more! Consider these:

1. OP amps as mentioned above. AD826 are very good, but you could try OP275 as well. If your DAC uses current Ė out, try AD8066 as I to V converter (Iím too lazy to check if the DAC youíve mentioned is current-out DACÖ)
2. Capacitors for smoothing / bypassing would have to go. Use Black Gates FK types for DC smoothing after rectifiers, and 0.1uF/50V NX type close to digital ICs without any other capacitors in parallel! Remove all surface-mount capacitors and other electrolytes and use ONLY 0.1uF / 50V NX! This applies to digital section. Analogue section can receive 100uF/16V N types - again without any additional small value capacitors in parallel.
3. Use external clock of your choice with dedicated power supply. For a power supply, use fast switching soft recovery diodes + FK Black Gates. Try to obtain silver wiring (solid core) and connect this power supply to your clock using this silver wire. Dedicated power supply is mandatory here!
4. Are you ready to do some back plate cutting? If yes, remove cheap captive mains cable and install IEC connector that will allow you to use high quality power cable(s). Try copper, silver plated, solid core or litz power cables. The choice of the power cable is what I call a fine-tuning of the finished product (CD player) to individual taste.
5. Remove output coupling capacitors and use only one (well, two for stereo). In other words, do not bypass output-coupling capacitors. Try WIMA, Black Gate type C, AURI caps. Value should be around 4.7uF min.
6. Usually, there are some Ďisolationí resistors that feed the current(s) from power supplies to all ICs in a CD player. The value is around 4.7 to 22 ohms, 1/4W. These should be removed and ferrite beads installed. A ferrite bead in combination with 0.1uF/50V NX cap is the best thing you could do to your CD player re: decoupling and isolation of stages.

I know it sounds like too much, but if you give it a go you will be stunned with a potential of your CD player

Best regards,
Nick
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Old 28th October 2004, 10:28 AM   #4
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Hi

Tried to Email you directly. Could you mail me the manual ?

cheers
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Old 28th October 2004, 10:36 AM   #5
GNAKED is offline GNAKED  Poland
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I need service manual to Nad541i. My mail: gnaked@poczta.wp.pl
Thanks
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Old 28th October 2004, 10:57 AM   #6
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Hi Guido,

3-4 months ago, I sent you a complete diagram of my DENON 1650 CD player. It appears that you have quite a collection of these diagrams and I was wondering if you are going to be kind to all of us as well and send as a diagram of a particular CD player that WE might need?

Regards,
Nick
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Old 28th October 2004, 11:11 AM   #7
Mosez is offline Mosez  Netherlands
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Nick,

Thanks for your extensive input. It certainly gives me something to chew on for a while.

Couple of questions after taking a first glance:

- Would you say your list is in order of effectiveness or even cost-effictiveness as well?

- What power supply would you recommend for the external clock solution? Do I have to take external litteraly, i.e. putting clock outside the box in its own encapsulation?

Cheers,


Daan
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Old 28th October 2004, 10:41 PM   #8
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Hi Mosez,

List is not in order of effectiveness. Upgrading only certain sections of a CD player is not going to give you the best out of your CD player. Usually, people upgrade analogue section and neglect digital section, transport section, power cables, interconnects, sound deadening. Upgrading only analogue section could 'magnify' the flaws in the remaining sections of your CD player. Upgrading only analogue section could bring louder and cleaner sound, but low-level details, speed, harmonic richness, a feel of being there with them in studio while recording, could be achieved ONLY if you upgrade the whole CD player, connectors and cables. Cutting the noise floor on power supply rails is Very important.

Note: In my reply above, I forgot to mention replacement of RCA connectors. Cheap 50 cents RCAs have to be replaced with higher quality connectors.

Re: 'external' clock: external to the existing content of the CD player. In other words, clock and power supply should be added, but installed inside of CD player. Clock could be any mentioned here on Forums. I use XO3. Bear in mind that maximum voltage for XO3 is 17V DC! Power supply is: 9 to 11 V AC transformer + full bridge rectifier + smoothing capacitors. With 10V AC on secondary, you'll get around 14-15V DC, which is exactly what you want for XO3. Transformer should give around 200mA min, but you can choose bigger transformers as long as you can fit them inside of CD player and as long as you do not go above 11V AC on secondary.

I hope this clears things a bit....

Regards,
Nick
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Old 29th October 2004, 09:37 AM   #9
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Quote:
Originally posted by Extreme_Boky
Hi Guido,

3-4 months ago, I sent you a complete diagram of my DENON 1650 CD player. It appears that you have quite a collection of these diagrams and I was wondering if you are going to be kind to all of us as well and send as a diagram of a particular CD player that WE might need?

Regards,
Nick

Nick,

Indeed I have my own archive, it partly consists of data that I paid for, which I won't share.

If you are in need of a certain manual, let me know, if I have it available I will share it, or eventuall make a hardcopy if not available in bits and bytes.

best regards,
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Old 29th October 2004, 09:50 AM   #10
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Thanks Guido.

Regards,
Nick
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Old 12th May 2005, 10:04 AM   #11
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Hello,
I just came down from the States to my hometown Georgia, brought down my system with me, among which is my NAD C541i CD player, which works on 110volt (USA) and now I am now in Georgia which is 230Volts.. can anyone help me if they know how the voltage could be changed? NAD says it can be done but it needs to be taken to the service centre and there is no service centre out here..
anybody.. any views.. will be most welcome.

Thanks in advance

Anyone having a Support manuel for C541i ??

Would be extremely grateful if you could mail it to me at :

sandroshvilli@yahoo.com
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Old 12th May 2005, 10:43 AM   #12
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Quote:
Originally posted by Khato118
Hello,
I just came down from the States to my hometown Georgia, brought down my system with me, among which is my NAD C541i CD player, which works on 110volt (USA) and now I am now in Georgia which is 230Volts.. can anyone help me if they know how the voltage could be changed? NAD says it can be done but it needs to be taken to the service centre and there is no service centre out here..
anybody.. any views.. will be most welcome.

Thanks in advance

Anyone having a Support manuel for C541i ??

Would be extremely grateful if you could mail it to me at :

sandroshvilli@yahoo.com

Hi

From what I see, it should be fairly easy. I got the manual from Franz Gysi, so I can help you out:

There is a jumper setting the unit for 110V, this jumper is J801. Remove that one and place the 230V jumper J802 instead.

They should be found close to the mains transformer.

Please take all precautions as you work with mains voltage connected equipment.

succes
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File Type: jpg nad541i mains.jpg (12.7 KB, 1921 views)
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Old 12th May 2005, 12:50 PM   #13
Mosez is offline Mosez  Netherlands
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Quote:
Originally posted by Guido Tent



Hi

From what I see, it should be fairly easy. I got the manual from Franz Gysi, so I can help you out:

There is a jumper setting the unit for 110V, this jumper is J801. Remove that one and place the 230V jumper J802 instead.

They should be found close to the mains transformer.

Please take all precautions as you work with mains voltage connected equipment.

succes
Hey Guido, are you collecting C541i manuals now? I sent you one last year too.

Anyway, Khato118, I'll send you a copy. Haven't started yet myself (I'm still waiting for my US visa) but as Guido stated it shouldn't be too difficult.
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Old 12th May 2005, 03:26 PM   #14
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Hello,
Let me first say this place in just GREAT ! full of wonderful folks..
I wanted one I got three service manuals..
THANK YOU.. Franz.. Janusz and Daan.
Even though the Player hasnít yet arrived from the States.
I guess when it arrives Iíll be knocking on these doors again !!
Till then,
Love you Guys !
Khatuna.
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Old 12th May 2005, 03:48 PM   #15
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Quote:
Originally posted by Mosez


Hey Guido, are you collecting C541i manuals now? I sent you one last year too.

Hi

Must have missed that one because of my way of archiving .... or did you send it to GuidoB ?

anyhow....

cheers
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Old 12th May 2005, 08:03 PM   #16
Franz G is offline Franz G  Switzerland
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Today, I modified my NAD541i again: I inserted a Kwak Clock.

Surely, this was the best step, what I modified up to now.

Unbelievable, amazing!

Greetings to Tiflis and the rest of the world

Franz
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Old 25th January 2006, 11:35 AM   #17
klitgt is offline klitgt  Denmark
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Do any of you guys who contributed to this thread own a schematic diagram of the NAD 541 or 542? If yes can you mail it to me at klitgt@netscape.net ?
Thank's in advance!
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Old 7th February 2006, 10:30 AM   #18
Al Raj is offline Al Raj  India
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Guys, I too rqst for schematic of NAD 541i Cd player
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Old 9th February 2006, 07:57 PM   #19
namcir is offline namcir  Philippines
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guys you are talking about voltages on the nad cd player, how about the frequency can it be used on 50 or 60 HZ also?
thanks for any info
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Old 10th February 2006, 01:43 AM   #20
janusz is offline janusz  Australia
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Default NAD c541i

Hi Al,

I have a service manual for the above. If you need a copy email me.

cheers,
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Old 13th February 2006, 08:59 AM   #21
klitgt is offline klitgt  Denmark
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I made som mods on a friend's NADC542 with great results:
Lower grain
More resolution
Better transparency
Cleaner sound
Better bass
(quote: Tentlabs.com)

BUT, there has come an adverse effect, that I did not notice in my own setup:
With power on the CDP but not playing a CD, and volume turned to MAX on the preamp, a noisy, crackling hiss comes from the tweeters in my friends setup . This did not happen before the mod, it was totally silent.

The mods are:
Coupling caps from the DAC to the opamps
C375 parallel with C377/C376 parallel with C378
replaced with cupperfoil paper-in-oil caps. They are quite large and are suspended in foam to avoid that they touch any components on the PCB.
The M302A crystal and the ceramics C328-339 removed and a Tentlabs XO2 clock is applied with a dedicated PSU (transformer, rectifier, smoothing elcap in parallel with a small 100nF MKT).
Muting transistors Q301,302,303,304 removed.

I do not understand why the sound has improved so much but at the same time this noise has been added to the system?

Well... what can I have done wrong ?? What can the noise be, RF pollution, digital noise picked up by the large PIO caps??

Appreciate some ideas to get rid of the noise
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Old 13th February 2006, 05:58 PM   #22
mlloyd1 is offline mlloyd1  United States
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might have been useful to apply your mods one at a time to assess impact. then, the cause would be clearly apparent and a little easier to "correctly" address.

is it too late or too painful to do that?

good luck,
mlloyd1
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Old 14th February 2006, 05:08 AM   #23
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Quote:
BUT, there has come an adverse effect that I did not notice in my own setup:
With power on the CDP but not playing a CD, and volume turned to MAX on the preamp, a noisy, crackling hiss comes from the tweeters in my friendís setup. This did not happen before the mod, it was totally silent.
2 things:

1. Re-install the muting transistors. Is the problem gone? If YES, consider relays - shorting the output to ground. Or, leave the muting transistors installed.
2. Try recording a wav file, but without any signal (silence) - like white noise. Transfer to CD-R and play it in the CD player. Is the crackling hiss / noise still there? If YES, it could be "something else" you did, or even a bad original design (yes, yes, I know - it's NAD!!). You see, the problem is noticeable only without muting transistors - you can not be 100% positive if the crackling noise problem was there BEFORE you started the mods, because the sound being played / reproduced could've masked the problem....

Extreme_Boky
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Old 14th February 2006, 07:35 AM   #24
klitgt is offline klitgt  Denmark
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Quote:
Originally posted by mlloyd1
might have been useful to apply your mods one at a time to assess impact. then, the cause would be clearly apparent and a little easier to "correctly" address.

is it too late or too painful to do that?

good luck,
mlloyd1

Probably the only way to identify exactly what caused the problem, it is possible. I never burn any bridges behind me!
To Extreme_Boky I can say that it is 100% sure that the bad sound was NOT there before the mods, whether there is a CD in the tray or not.
thank you for helping!
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Old 14th February 2006, 11:00 AM   #25
klitgt is offline klitgt  Denmark
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Quote:
Originally posted by Extreme_Boky


2 things:

1. Re-install the muting transistors. Is the problem gone? If YES, consider relays - shorting the output to ground. Or, leave the muting transistors installed.
2. Try recording a wav file, but without any signal (silence) - like white noise. Transfer to CD-R and play it in the CD player. Is the crackling hiss / noise still there? If YES, it could be "something else" you did, or even a bad original design (yes, yes, I know - it's NAD!!). You see, the problem is noticeable only without muting transistors - you can not be 100% positive if the crackling noise problem was there BEFORE you started the mods, because the sound being played / reproduced could've masked the problem....

Extreme_Boky

In another thread is is recommended to bypass the transistors at the output (muting transistors??)

Tweak report NAD 510

How would this be recommendable if it causes problems?
I did remove (not bypass) Q301-304 shown in attachment.

What is the purpose and the function of these transistors?
Why could their absence cause the noise?
And once more to avoid misunderstandings: The noise is there if I turn up the volume to max. at the preamp without playing a CD.
Before the mods I could turn up the volume to max. without any noise, only a weak hiss if I place my ear 1 inch from the tweeters.

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