Just found a couple of authoritative articles of 2012 by Bill Whitlock, President of Jensen Transformers Inc. since 1989.
The Truth About Balanced Audio Interfaces In Systems
and the following one that deepens and mentions the previous one (for more technical readers)
How To Find Problems That Degrade Performance In Balanced Audio Equipment Interfaces
From the first article you can read the following:
Now consider this quote from a part of the informative annex of lEC Standard 60268-.3: "Therefore, only the common-mode impedance balance of the driver; line, and receiver play a role in noise or interference rejection. This noise or interference rejection property is independent of the presence of a desired differential signal. Therefore, it can make no difference whether the desired signal exists entirely on one line, as a greater voltage on one line than the other, or as equal voltages on both of them. Symmetry of the desired signal has advantages, but they concern headroom and crosstalk, not noise or interference rejection."
An accurate definition is: "A balanced circuit is a two-conductor circuit in which both conductors and all circuits connected to them have the same impedance with respect to ground and to all other conductors The purpose of balancing is to make the noise pickup equal in both conductors, in which case it will be a common/mode signal which can be made to cancel out in the load."
Hoping may be a definitive word to thin out confusion and misunderstandings (first of all mine).
The Truth About Balanced Audio Interfaces In Systems
and the following one that deepens and mentions the previous one (for more technical readers)
How To Find Problems That Degrade Performance In Balanced Audio Equipment Interfaces
From the first article you can read the following:
Now consider this quote from a part of the informative annex of lEC Standard 60268-.3: "Therefore, only the common-mode impedance balance of the driver; line, and receiver play a role in noise or interference rejection. This noise or interference rejection property is independent of the presence of a desired differential signal. Therefore, it can make no difference whether the desired signal exists entirely on one line, as a greater voltage on one line than the other, or as equal voltages on both of them. Symmetry of the desired signal has advantages, but they concern headroom and crosstalk, not noise or interference rejection."
An accurate definition is: "A balanced circuit is a two-conductor circuit in which both conductors and all circuits connected to them have the same impedance with respect to ground and to all other conductors The purpose of balancing is to make the noise pickup equal in both conductors, in which case it will be a common/mode signal which can be made to cancel out in the load."
Hoping may be a definitive word to thin out confusion and misunderstandings (first of all mine).
Yes. The technical specifics are what define each term. I only intended to suggest some appropriate term names themselves.
As I learned from reading Whitlock, a balanced interface is essentially a Wheatstone Bridge. IIRC, the source’s two output impedances form ther the two left most arms of the bridge, while the receivers input impedance service as the two rightmost arms.
So glad to hear this from you.
Edit: By the way, I did not understand almost a single word of what you just wrote... 😀
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See page 1, of linked Jensen AppNote AN002. If that helps any. 😴
https://www.jensen-transformers.com/wp-content/uploads/2014/08/an002.pdf
Here’s also a couple of presentation slides by Whitlock himself about it essentially being a Wheatstone Bridge:
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I've dealt with metrology instruments on and off over the years.
They tend to be designed to be fully impervious to noise, introduced both by the Vcc and by RF noise.
Of course, they cost $$$... although in the last few years, with the advent of large scale ASIC construction, it's gotten a lot cheaper to make metrology instruments.
Remember what we used to pay for a scope or a spectrum analyzer before?
I remember putting a 100Kohm between RX+ and RX- and a 1Mohm betweewn RX- and GND.
That keeps the differential-mode impedance (the input impedance which the driver sees) at 100K, while setting the common-mode impedance of the receiver’s input at 1Meg. The higher the reciever’s common-mode input impedance, while also keeping the driver’s common-mode output impedance relatively low, the less sensitive is a balanced interface to impedance mismatches within the interface.
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Hmmm.... I only have an M-Audio and an RME AD/DACs that do balanced at the pre-amp level. Nothing else in my home audio museum drives balanced at the line level.
I was planning on running the NCore with a B1 or a B1K and an adaptor..... neither of which is balanced. How hard would be it to match two B1s to each other, in the same chassis?
There aren't many balanced preamps out there... perhaps an ARC LS17SE?
But then, what would I gain other than having the balanced interconnects driving the amp? I mean, I could run the RME into the balanced inputs but my LPs are unbalanced.
Currently, my Aleph 2s and 5s sound fantastic and they are single ended... I'm not too keen on spending money on a balanced preamp just to drive the NCore amp to whatever Bruno thinks it's "best". Perhaps, I like 2nd order distortion....
I did not (yet 🤓) read the page you indicated, but I appreciated the 2 slides that proved to be very explanatory. Thank you.
FYI - Here’s the link to a ‘whitepaper’ version of Whitlock’s excellent full slide-presentation that’s referenced above. Very informative content.
https://www.jensen-transformers.com/wp-content/uploads/2014/08/generic-seminar.pdf
https://www.jensen-transformers.com/wp-content/uploads/2014/08/generic-seminar.pdf
To be honest I think nobody can answer your demanding questions if not yourself as your choice must then derive a pleasure (even also mental), otherwise for what reason to do it apart from the fact that it is recommended by the manufacturer?
Furthermore it also depends on how much you want to get from your choice.
I chose to buy a balanced preamplifier exactly for that reason (the derived pleasure of which I was sure of and because I wanted to get the most possible) as I personally did not accept even for the hypothesis of using a workaround to connect my power amp, and now that you've led me to think about this I can say that it was also because I always liked the idea of using balanced line, but I had never had the opportunity to do it.
For what it's worth, I don't think I would ever spend 4,000 USD for the ARC preamplifier you mentioned to combine with a power amp that costs 1/4, but the money (and the deriving pleasure) is yours.
If you are looking for around and around you could even find a preamplifier that costs the tenth part of what you thought and is regularly compared to a competitor of the cost of many and many times higher.
But if you think I suggest you that preamplifier name then you would be wrong, because I won't tell you... 🥷 😀
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On HiFi shark I can see that line stage going for the mid $2000. And I kind of like it. I've been thinking of getting an ARC VT200 for quite a while, and I still have a D70MkII, so I have a soft spot for those silver boxes with black handles.... even perhaps for an SP14/15...
But the idea of marrying two B1s into a single chassis, in balanced mode, is intriguing. I wouldn't do the B1K, I think, since that one is a bit more idiosyncratic.
Besides, why would my questions be "demanding"? I figure my questions are typical of what drives an audiophile:
Will it sound better?
Will it add more cables, lights, switches?
Can I get it used?
Can I get it DIY?
Will it cost too much? (usually this disqualifies commercial MSRP products)
BTW, the B1K is a giant killer.
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So the interconnect is a balanced impedance, but only the hot pin is actually driven.
Look at it another way. For single ended pre-power connections in domestic they tend to be around 2V RMS (with notable outliers), and balanced tends to be 4V RMS as one feed is inverted compared with the other. Any sane balanced input would take a 4V RMS signal on the hot pin and nominally gnd on the cold and every textbook has examples of inputs that do this but I've seen circuits where that won't work as it clips. Actually takes some doing to get it that wrong, but I've seen it.
And sorry for not using dBU. It's late and brain is mangled.
How hyper-sensitive you seem! Don't let one word pass! 😳
But basically I understand you since maybe I'm also a little done like this... 🙄
Sure they are (and they are mine too)!
However, please note that your quoted and very specific questions - mentioning many models of different devices some of which I didn't even know - have appeared demanding (BTW, had you noticed the first italic font style and then that of now?) not in absolute, but to me!
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Well, I'm an old guy, so I'm sort of specific what stuff I want. When I buy something, I normally have been looking into it for at least five years... and I'm in no hurry for the "latest and bestest", so I normally look into used stuff, and yes, I'm very specific what I want.
Note: those Sony VFETs sure are tempting, but they are hard to come by, so I pretty much gave up on them. The same for the Aleph 2s, so I went the DIY route and got mine fully spec'd to my anal retentive needs... would you believe mine are fully symmetrical... not only on the layout of the IO sockets but also on the layout of the power supplies and power boards... I actually wanted a red light for right and white light for left, but I had to settle for the standard blue (since, as you know, blue LEDs sound better in Nelson's designs... ;-D ).
Ideally, I'd get a dual B1 preamp with a balanced set up, three inputs, a tape monitor and a metrology power supply. That would give me the "balance" control I really want as well by having one volume for R and L each.
And yes, those TVC preamps look very good, very, very good. Here's one that I almost bit on... except it lacks the SE outputs and those holes for the missing tape would have always bugged me...
https://www.usaudiomart.com/details/649626416-bent-audio-flex-passive-tvc-preamp/
It's like buying a top of the line Honda car, with ALL the available bells and whistles and then you notice that there is a rubber cap on the dash for some doo dah that you couldn't get in your car.. I mean... Top Of The Line, Fully Loaded and WTH is that missing feature?
That stuff bugs me, maybe I should put a blue LED on the missing feature hole and the engine will sound better? Put a pot and bias it for more 2nd harmonic from the exhaust!
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Very nice post that I understood and shared, thanks for replying this way! 👍
Think that instead Bruno use all of them of a red color because he claims they would be the most silent in absolute... 😛