Mutec MC-3+

[accwai]

Let me pls add this:

LPFRS is the clock my 10 MHz journey started with - good for a first trial.

OCXOs are normally a better choice for this application - mid/long term stability is less important here...

 

The LPFRS has 50 ohm output connector and cabling, but the MC-3+ has 75 ohm input. I would assume the internal word clock termination needs to be disabled as per page 20 on the manual, and then externally terminated with a BNC-T piece and a 50 ohm terminator instead right?

 

That would probably apply to most scientific and industrial type equipment as well, e.g. Orbital Research POS OCXO.

[accwai]

Short answer: do use 75 ohm cabling to connect a 10 MHz source do the 75 ohm specified input.

 

Longer answer adresses two topics:

 

• line impedance describes who waves are traveling on a line. As long as the impedance does not change there is just a wave traveling in just one direction: from source to load.
  [ATTACH=CONFIG]15658[/ATTACH]
  from: Reflection coefficient - Wikipedia, the free encyclopedia
  

 

=> your cable impedance should have the same impedance as its termination:

75 ohm in case of a MC-3+ 10 MHz input

 

[...]

 

Don't bother about impedance mismatch at the osc. output - most likely its Zs will differ from say 50 ohm anyway. As there will be no reflection from the proper terminated line end (MC-3+), all is fine.

 

hth

Ulli

 

But isn't a change from a 50 ohm source to 75 ohm cabling a break in impedance already? For example, LPFRS has CMA output which is a 50 ohm system. If you link a 75 ohm cable to a male CMA connector on the oscillator side, there's a break right there. Wouldn't running all the cabling in 50 ohm, terminate with a 50 ohm BNC terminator through a T-piece and run the MC-3+ with high impedance input be less of a break in the pipeline?

[accwai]

Sure it is a break.

But, 1) what is the impedance inside the osc. before the signal reaches the connector? and 2.) line impedance is a physical description of what happens on a wire which is a valid description only in case cable length is long compared to wave length - which is about 20 m for 10 MHz on a cable.

 

Thanks for the perspective. However, given the good job that Mutec did with MC-3+, I think the new 10MHz clock would merit serious consideration when it comes out. Then impedance mismatch like this would be a moot point.

[accwai]

Hi Joel,

I'm beta-testing a lab version of the MC-3+ USB and can now confirm the rate is switched automatically to the rate on either inputs, be it AES/EBU or be it USB.

 

And - first impression after listening to not yet final hardware:

USB feeding the MC-3+ USB gives simply intriguing sound quality.

 

I'm seriously considering getting one when it comes out and cascade it to an existing MC-3+. Could you elaborate on what's "intriguing" about the sound quality? Thanks.

[accwai]

[...] Upon product launch, only the DoP formats at 64 and 128 will be supported, [...]

 

Any idea when the product launch would be?

 

If you don't mind me asking, what exactly were you hoping to do? What source? What receiver?

 

I'm not the OP for the DSD question. But in my case, the plan is to have the MC-3+USB goes AES to a regular MC-3+, then from the 2nd MC-3+ AES to the DAC. The DAC supports DoP on the AES input up to 64Fs. And I'll be feeding PCM most of the time anyway. Shouldn't be any problem right?

[accwai]

Definitely this fall. It could be as early as September, but a few things are still up in the air. Will keep you posted!

 

That would be great. Thanks.

 

At this point the MC-3+USB would convert the DoP/DSD Stream to PCM and not distribute the the DoP-Signal via AES3 or S/P-DIF. So in this case, the second MC-3+ would just do a straight reclocking (i.e. you have a twin-reclocking cascade) before sending the signal to the DAC. There wouldn't be a way to maintain the DoP Stream all the way to the DAC. Even if the MC-3+USB would support it, it wouldn't work with the MC-3+. Does that make sense?

 

Not really

 

How about this: If the MC-3+USB would leave the DoP alone and hands it off to the next MC-3+ as is via AES, the second MC-3+ doesn't know what DoP is, so it would be passed to the DAC as is. The spec sheet for the DAC says it can accept DoP over AES, so it would be recognized at that point. If the original stream is PCM, it would again pass through the chain and be recognized at the DAC. Is that possible?

[accwai]

According to the link that SwissBear posted in this post http://www.computeraudiophile.com/f6-dac-digital-analog-conversion/mutec-mc-3-a-17300/index6.html#post507163 the MC-3+ USB by itself sounds better than multiple MC-3+ units cascaded together.

 

The poster in the German forum said one MC-3+USB is as good as cascading 3 MC-3+, but putting an MC-3+ behind MC-3+USB does improve things further. The twist here is a Morion MV98a OCXO is attached to the MC-3+ at the back. And the poster also stated that things actually deteriorate when the MV98a is hooked to the MC-3+USB. The theory being the internal clock for the MC-3+USB is better than the Russian oscillator. That leads one to wonder about a couple of things...

 

What happens when 2 MC-3+USB are cascaded? The poster talked about doing such test but no results were posted.

 

If USB input is not needed, what happens when the MC-3+ (no external clock) is chained in front of the MC-3+USB? Presumably putting the better clock closer to the output would be better?

 

Now question for Julian: MC-3+ is currently still available. Is it the same MC-3+ as a couple years back? Or is it an improved version using the newer technology as MC-3+USB? If not, is there any plan to upgrade the MC-3+ in the near future? And would there be any upgrade plan for existing MC-3+ owners if an improved version comes out?

 

Oh and what happened to the Ref 10? A prototype was shown at the end of 2014 but never heard from again. Is there any plan to bring it to market still?

[accwai]

Hi accwai,

 

Very interesting development indeed. Thank you for pointing that out :-)

Best

 

You're welcome

 

[...] Correct, the MC-3+USB with it's superior performance should be placed last in the chain prior to the DAC. So if you already have an MC-3+, using it in a chain with the MC-3+USB will actually improve the performance!

 

I really have no need for USB input. So that will be the configuration then.

 

By the way, just realized the coax input has gone from RCA to BNC on the MC-3+USB. On coax, for a long time I've been using a WyWires Blue RCA-BNC cable through a BNC-RCA adapter into the MC-3+. Recently upgraded to WyWires Silver RCA-RCA cable, but now the BNC input on the MC-3+USB... So putting the MC-3+ in front would allow me to keep the WyWires Silver too. This is going to be totally awesome!

 

Let's just say this: the High End show in Munich is coming up in May and MUTEC will have a booth for the first time ever :-D

 

Thanks. Really looking forward to that.

 

By the way, in a cascade, should the clock go to everybody in the chain, or just one?

 

Andy

[accwai]

Our German friends from aktives-hoeren.de • Foren-Übersicht look excited about the idea of plugging a 10 MHz clock into the MC-3+/MC-3+ USB. Does one have to be able to send a clock signal to the DAC to fully benefit from this improvement ?

 

Perhaps, but that's probably a moot point since not many DACs these days have clock input. So MC-3+ would be the DAC's clock input in practice. Take a look at the beginning of this thread.

 

Has anyone an idea about the price tag of this device ?

 

It's competing in the same space as atomic clocks. Probably won't be on the low side...

[accwai]

The voltages were measured with a Fluke 114, so it doesn't include "much" lower order RF. Today, I moved the Mutec and the Intona about retaining the same cabling and the voltages dropped to about 85 mV again, so thought uh oh, but everything played well, so go figure Maria. [...]

 

If I read correctly, you seem to be using the voltage between the USB shell and AC ground to predict how good things would sound. And the higher the voltage, the better things would sound. Is that correct? What's the reason behind that?

 

People who do AC polarity measurements normally choose the polarity that shows lower component ground to AC ground voltage. But that's done component by component, not in a live system with everything hooked up. Off the top of the head, I don't have anything in my system that is more than 50mv vs AC ground when measured in isolation...

[accwai]

[...] yes, I did listen to it and found it amazing. It impressed me even more than the new Mutec, in the end I think both devices are absolutely worth the money.

Since I do use my Mutec as a proper studio clock every now and then, I should add that the Acousense AFI does not provide this functionality. It is "just" a reclocker for mastering/listening purposes.

 

The Acousense website had been down for a short while. It's back now and I just did some reading with the help of Google translate. Looks like that are two models, AFI and AFIS, both of which can take a USB module. And apparently you can customize the input and output connectors when you order. Still not clear about the difference between AFI and AFIS though. Which model did you listen to? And would you mind elaborating on what configurations of Acousense vs Mutec you compared, i.e. source, connection type, cascading etc. And what specifically does the Acousense do better than Mutec?

 

It's interesting that Acousense seems to be putting a lot of emphasis on impedance match along the digital chain while downplaying the importance of accuracy/stability of the clock. Does that mean high stability external clocks are ultimately futile?

 

Also, I vaguely recall reading claim that the Acousense makes a stock laptop sound like a highly optimized computer source. How does MC-3+USB compare? My experience with the old MC-3+ is that it's still very easy to tell the difference between quality of the upstream transports and digital cables.

[accwai]

[...] Developers have learned their lesson and equipped their latest babies with USB inputs and therefore became more interesting to the world of audiophiles.

 

[...] as I said, a friend from Germany paid me a visit and took his AFI with him. We did compare the reclockers, but in the end we only had about an hour, because we were bound to see a few laddies at my local pub. [...] It is a bit hard to tell what made the Acousense even better than the new Mutec other than it sounded even more natural to me.

 

From what I've read so far, the Acousense has a pretty tricked out USB interface. Whether this USB interface is the reason for it being perceived to be better than Mutec is a very important question, for me at least. Because unlike most of the audiophile world, I'm pretty entrenched in physical CD. So much so that in the past year, I have more or less given up on building a computer front end, which in turn means I have no need for USB.

 

And there's this bit of information in the USB/SPDIF converters thread:

 

The most comprehensive information about AFI and AFIS can indeed be found in the forum Nikander linked to. At least the larger model (4 inputs, 2 outputs, configurable) is listed on the manufacturer's page. Prices [1] are AFIS w/ USB 1980 €; AFIS 1770 €; AFI-USB 1166 €; AFI 640 €; AFI w/o PLL 580 € (including sales tax).

 

If I understand correctly, Acousense AFI should work for my purpose, especially if I put it behind an MC-3+ in a cascade. And according to the above, it would cost quite a bit less than a Mutec MC-3+USB, which I won't be using to the fullest. More options to look into I guess.

[accwai]

[...] The clock is a TEMEX LPFRS-01 salvaged from an old telco installation; I bought it second hand on ebay some years ago. The performance of this clock source is OK, but not up to modern standards. I had the chance to test Orbital Research POS some time ago, it was slightly better, but the improvement (for me, in my system) was not enough to justify the expenditure.

 

Interesting. How did you get your hands on the Orbital Research? Is it configured with 50R output? How is that terminated? What kind of power supply do you use? And if you don't mind, how much is the whole package?

[accwai]

Well, as a matter of fact I tried :-). I used the AFIS first to benefit from the high-end isolation, and sent the AES/EBU output to the Mutec cascade. In fact this does not help a lot. On the opposite I would say that the benefits of the clearer voices separation when listening to 'La Traviata' disappeared. So I left the test here for the time being.

 

Wouldn't you want your best one to be at the tail end to catch any junk that passes through or are generated at the front of the cascade?

[accwai]

My understanding is that the best one as far as USB isolation is concerned is the AFIS, and the best one as far as clock precision is concerned is the Mutec. This is why I decided to put the AFIS first and the Mutec cascade last.

 

BTW I tried the other way around and this was not better.

 

But what I understand from the AFIS is that it does not exactly behave like a reclocker, which is essentially a filter for jitter (clock phase noise) ; I assume it acts, at least in my configuration which is based on an async DAC, in just isolating the HF interference on the USB port, cleaning the USB data from the clock data and plug the sound data on a clean clock signal. Therefore, there is no need for a second reclocking in this configuration.

 

Just my interpretation. Would you agree ?

 

Really hard to say. Acousence's approach seem to be more radical. More audiophile it you will For myself, I'm just looking for the cheapest way out. But there doesn't seem to be a clear winner wihtout trying the stuff out first, which is not going to be cheap

[accwai]

Hi, for those with cascaded MC-3+ or MC3+-USB, what length of cable do you use between units? I'm planning to stack the units and have a 3" AES/EBU in between. Any reason it needs to be longer than that?

[accwai]

An Xlr connector is already 2.7in. Allowing for termination and bending radius the cable length would need to be 9 in minimum. Nearest off the shelf is 12in or 30cm.

 

I'm starting to make some changes to my system which would change the physical layout quite a bit. That requires significant alteration to the length of a number of existing cables. I'm think about having this little guy tag along in that cable order. But I'll talk to the company about bending radius. Thanks.

[accwai]

[...] The MC's do get warm, if you have the room, side by side stacking is an alternative if ventilation is a problem.

 

Hmm... I'm rather low on space. Side by side can be a problem. May need an extra shelf. Thanks for the heads up.