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Lil Caesar

NAD M51 Listening Impressions...

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scumbag   

Ok, I stand corrected though I'm not sure what your aversion to LDR's is;)

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CraigC   

 Thanks for your fast reply, missed it.

I did have a M51 previously which I sold due to lack of use. I did like it and was contemplating buying another, however given it is a 5 hear old design somebody else should have come up with an improvement by now.

I would be interested in the audio performance, using files from a nas device. The volume controls aren't important to me.

Edited by CraigC

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scumbag   

I personally went from an nad m51 to the Klein dac and found it a big step up.  I can only imagine what the Klein 2 would bring to the table. Clay's implementation of the akm chip is excellent. A great dac chip surrounded by great components in a well thought out design. 

Mark 

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24 minutes ago, scumbag said:

I personally went from an nad m51 to the Klein dac and found it a big step up.  I can only imagine what the Klein 2 would bring to the table. Clay's implementation of the akm chip is excellent. A great dac chip surrounded by great components in a well thought out design. 

Mark 

 

I have to say I compared the initial klein DAC to an Electra.  There wasn't a lot of difference between the two but the Klien was value for money as the Electra was 4X the price.  

The klein had to be returned because it was a loaner.  My next visit was comparing the Electra to the M51, no Klein was present and have to say that the Electra was a more forward and rounded presentation. But there was something that the M51 presented that the Electra missed entirely.   There were 3 sets of ears  there and agreed that the Klein was better to the ears than the M51.  Whether they heard what the M51 added, I didn't get the chance to asked, because I asked myself was it worth the mentioned!

The Klein 2 would slightly improve on that,  but I'm only guessing. 

It be interesting what the Gustard version of the AKM4497 dual chip would bring to the table.  Don't forget this unit also has a resistor ladder relay based volume control, and what interest me is that it has XLR.  I know what everyone thinks, but I find XLR a huge advantage over RCA, especially for a stock DAC chip because the output is XLR and not single ended.

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Spark   

Hello again.
I have been doing some tests and I will comment on the current results, although there are still some more tests to do. And I will put a few pictures about it and some comments about them.

Also later, I'll post photos of a couple of USB converters I'm using with very good results.


I suppose you will already know it, there is a version of the M51 called Rowen, that apparently has some elements of the different analog output stage.
It's a shame not to know, because it would be easy to change them and a cheap upgrade.


I was able to get an electrical schematic of the NAD DAC C510, on the analog part, it is practically identical. I do not know if the quality of components is the same, but the numbering does.
The fact is that I used continuous filters to filter the output of the LM317 and LM337 but with poor results, the sound loses quality significantly. I do not know the cause, since the filters really are fun and measurable.
Probably a mass problem.

 

The red and black colors, are inverted with respect to logical correspondence of positive and negative. There are several cables, but they are all connected to the same point.

 30kpzky.jpg

 

 

2pyz480.jpg

 

Operational LME49990 and the nearby controller that powers it.

 

9prl7a.jpg

 

 

Try the filters that I currently have installed on an amplifier. That as I say, does not work. The sound instead of improving, it got worse.

I have orders, two substitutes for the LM317 and LM337 of very low noise. They are not expensive.

http://www.ebay.ie/itm/TPS7A3301-Ultralow-noise-LDO-regulator-3V-18V-1V-step-1A-LM337-79x-replace-/252533452377?hash=item3acc2aae59:g:msEAAOSwGtRX1PN-

http://www.ebay.ie/itm/TPS7A4700-Ultralow-noise-4-VRMS-LDO-linear-regulators-1-4V-20-5V-LM317-replace-/252710100444?hash=item3ad6b21ddc:g:18wAAOSwgmJX1PKh

 

 

 

5btdnc.jpg

 

30hyl2g.jpg

 

The source by the test, install it in the box of the Gustard U-12.

 

j7caw8.jpg

 

bbzt4.jpg

 

 

I also made a metal separation, but it is possible that to test, change the switched source to a linear one.

 

5y9swp.jpg

 

For now, it will stay.

 

2cqcm5c.jpg

 

I'll be putting some updates as I do. A greeting.

 

 

 

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L J T   

My NAD M51 decided to stop clocking onto every signal except the USB input last week

I swapped digital cables, sources, power points, reinstalled firmware from 1.39 to 1.50 with no success.

It has been sent off to a preferred service agent and I am music-less until it's return.

By looking at the modifications posted above, there doesn't seem to be much user serviceable parts?

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Spark   

Hello L J T. I feel the problems you've had.

The tricky thing is to figure out where the fault may be. If it is a problem in a particular component, several etc. Otherwise it could be a matter of changing components that is not complicated except for some larger integer.

I have the electronic schematic of the NAD C510, which is very similar in case you out of interest.

In this model, the optical inputs, AES and coaxial, pass to the main processor through an integrated AK4118AEQ
SPDIF interface.

 

¿Did it stop working for no apparent reason? Power cut etc ¿Did you see the interior in case you saw any broken components?

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L J T   

Hi Spark, thanks for your reply. I was listening to music and pressed the input selector button and found it stopped locking onto digital signals.

I always run my gear through power conditioners and practice good connection and disconnection of components ensuring all power is turned off.

I just heard back from the repairer and was notified that the AES, Coaxial and Optical inputs stopped working because of a short inside the IC that operates all these inputs. Of course it is the first M51 that the repairer has seen to exhibit this fault.

A replacement IC has been sourced and should be installed by 1 week.

If the replacement IC fails to work, I am left with a USB DAC with volume control. Not all doom and gloom I guess. It will be moved to my PC setup and I will be on the hunt for a multiple input DAC with electronic volume and preamp capabilities.

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Spark   

It is then possible that the integrated one, is the one you are talking about or near power circuitry.
I hope it works out for you. Anyway, as I tell you, if you know about an electronic technician, with the scheme I have, it would be possible to make some more attempt.

I have been making improvements lately in my equipment and now is when I am enjoying the M51 in its measure. It's a good CAD.
Regards and luck.

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