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 81 
 on: October 14, 2014, 10:39:40 am 
Started by christoffe - Last post by PeterSt
Hey Alain,

With the notice that you should be sleeping at this time and that the danger exists you will never get some sleep any more for this night :

I thought you dared to get rid of the pre-amp long ago my now ?
Apparently not.

Using the preamp does not make sense in this realm (of the BNC cable) although it should be able to improve just the same. But why go through the effort if you can do half of it anyway, the other half being destructive behind your back ? Thus :

a. Using the preamp is for the worse (and if too much digital attenuation is needed get another power amp swoon);
b. Output impedance of the preamp will be 600 Ohm or so, and thus this (75 Ohm) does not apply there;
c. Meanwhile nothing really matches between preamp and poweramp, but this is another (new) story (but read : what prevents the reflections in that connection ?).

I tend to say : Do it all (meaning ditch the preamp to begin with) or do nothing. But this is not really different from me "forbidding" to use a preamp. Between quotes of course, but you know ...

Sweet dreams ! (ahum)
Peter

 82 
 on: October 14, 2014, 10:16:23 am 
Started by christoffe - Last post by AlainGr
Peter,

I understand what you mean. My concern is that while I use a preamp, it would mean that I need 2 pairs of cables and I really am not sure I want to go through the process of having my components fit with BNC connections... Not that I don't understand the benefits, but... And I am not sure why...

Alain

 83 
 on: October 14, 2014, 09:11:23 am 
Started by CoenP - Last post by PeterSt
Quote
Edit: thinking about it again... I may not have understood your point - you mean that the Sotm will not work if power is not applied first at the USB port ?

Alain, exactly. I too wasn't the most clear, but logically there was nothing in my mind about the power to the card itself. So there's a dipswitch on it for USB power, and without that set to On the NOS1 will not work. Again, no clue why but the card will be not compliant somewhere. And not to forget, the card's latency is also not on par, so something is fishy in there. Do notice though that this experience is from when it was first out (over 3 years ago by now ?).

Regards,
Peter

 84 
 on: October 14, 2014, 09:07:22 am 
Started by christoffe - Last post by PeterSt
Hi Alain,

No, doesn't change a thing. But it (also) depends on how it works and I - without really knowing all about it - wouldn't trust "impedance conversion" as such anyway. I have been looking into that earlier, and although stuff exists at the mere chip level (OpAmps), I saw nothing that got me excited. I gave up on it (sometimes I need to do other things as well) with those Neutriks also in mind. And about that one more thing :

As you can see in the "specs" of them, it is easily told that it can convert to 110 Ohm impedance of XLR.
Eh, what ?
I think it is good to know that, like with RCA, there is nothing in "XLR" that makes it 110 Ohm. That is, if I am correct on this, but others may know better.
But if I am correct on this, it also means that such a Neutrik is just an adapter but probably an expensive one (I did not look). Also, for the XLR guys, this won't be making a balanced signal of it. Or ...

Now I suddenly recall what I obtained my Jensen's for - it was exactly for that, but the other way around of what we want. So these turn a Singled Ended (RCA) signal into balanced, route the balanced signal to the other end and there you can make it SE again with such a same transformer. And this did not work out (way poor measurement figures). I also recall that I dug them up last week to see whether they could be used (for you) to what we want : have the SE coax as the transport means of the signal, and turn that into balanced at the (amp's) end of it. But the connections are not suitable for this because "the other way around".

I really wish I could measre this by means as needed, because this guessing leads to nowhere. And if someone finally has a good reference (could be me at this moment) then what ? keep on trying other solutions until one seems to work out the same BUT easily applicable to everybody ? Quite undoable (time, $$).

Peter

 85 
 on: October 13, 2014, 08:10:46 pm 
Started by christoffe - Last post by AlainGr
Todd and all,

Quote
I was using an electronic crossover with very high grade Jensen transformers on the inputs and it definitely took the life out of the sound of the NOS1.

A few years ago (during the development of the first NOS1) I tried to use those too for galvanic isolation (still have them in the drawer here - costed 130 euros pp IIRC). You already don't want to see the measurement results with them in. Really.
I don't know about the Neutriks, but I sure have been looking at them for you. But if the principle is the same (literally transfomer based) then almost sure it's a No.

Regards,
Peter
These Neutriks are said to be "passive"... Does it change anything (or not) ?

Alain

 86 
 on: October 13, 2014, 08:05:07 pm 
Started by CoenP - Last post by AlainGr
The SOtM won't work without power. Don't ask me why. Otherwise the power is not needed for the NOS1(a).

Peter
Hi Peter,

The sotm card needs power of course... I was talking about the switch that "cuts" the 5V that otherwise would be sent through the USB cable...

Here is how they tell it...

SOtm tX-USBexp Features
USB port
USB 3.0 compliant xHCI host controller
PCI express x1 Gen2 interface
Support for super-speed, high-speed, full-speed, and low-speed
USB port power on/off function
Over current protection
ESD protection


Alain
Edit: thinking about it again... I may not have understood your point - you mean that the Sotm will not work if power is not applied first at the USB port ?

 87 
 on: October 13, 2014, 07:39:24 pm 
Started by christoffe - Last post by PeterSt
Todd and all,

Quote
I was using an electronic crossover with very high grade Jensen transformers on the inputs and it definitely took the life out of the sound of the NOS1.

A few years ago (during the development of the first NOS1) I tried to use those too for galvanic isolation (still have them in the drawer here - costed 130 euros pp IIRC). You already don't want to see the measurement results with them in. Really.
I don't know about the Neutriks, but I sure have been looking at them for you. But if the principle is the same (literally transfomer based) then almost sure it's a No.

Regards,
Peter

 88 
 on: October 13, 2014, 07:20:34 pm 
Started by christoffe - Last post by toddn
Hi Juan,

I've used Adaptors like these for digital connection from a source to a D/A converter, but I would be extremely hesitant to use any kind of coupling transformer on the pristine analog outputs of the NOS1. I was using an electronic crossover with very high grade Jensen transformers on the inputs and it definitely took the life out of the sound of the NOS1.
BTW, I am currently running standard BNC to XLR with the 50 ohm cables on my low frequency amps and like what I'm hearing.
I have modified the inputs on my midrange/tweeter amps with 50ohm BNC inputs but still connecting my 50ohm BNC cable using 50ohm BNC to RCA Adaptors on the NOS1a outputs and it has been truly transformative to the sound quality compared to the balanced cabling I was using.

Todd

 89 
 on: October 13, 2014, 06:41:53 pm 
Started by CoenP - Last post by PeterSt
I was planning to buy this one: https://www.kabeltje.com/supra-usb-a-b-kabel-2-meter.

Real (?) 90 ohm, because that might be the most important.

At last it "has it" in the specs : http://www.jenving.com/products/view/usb-2.0-a-b-blue-1m-1001907573
... and this is rare to begin with. But since this cable is often reviewed well ... looks good ?
The ones I found myself with explicit 90 Ohm spec (and then still wth +/-15% because that *is* the USB spec) can be counted on one finger and then still have to be made yourself (with the connectors).

So good ? And for 45 euros ... a no-brainer I suppose.

Stanley, nice find !
Peter

 90 
 on: October 13, 2014, 06:37:15 pm 
Started by CoenP - Last post by PeterSt
The SOtM won't work without power. Don't ask me why. Otherwise the power is not needed for the NOS1(a).

Peter

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