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Balanced v Unbalanced

Discussion in 'audio' started by SteveG, Apr 30, 2019.

  1. Arkless Electronics

    Arkless Electronics Trade: Amp design and repairs.

    I've said both can work well and tried to be "balanced" in my posts on this but if you're going to be like that then I'm right and you're wrong:p Oh and I've designed plenty of instrumentation and 90% has been unbalanced.

    Normal service may be resumed as and when we are debating something you don't manufacture;)
     
  2. March Audio

    March Audio Trade: March Audio

    It's not a case of being like anything, the usage in professional environments for specifically the reasons of ensuring best signal integrity bears out what I say. To say otherwise you are simply arguing black is white.

    And don't misconstrue what I'm saying; I'm not arguing that SE is a big problem or doesn't work well enough in most circumstances, just that balanced is overall a more robust interconnect system which I personally would always use as a first choice.

    So what instrumentation have you manufactured and where is it used?

    My background is with Rolls Royce Aero engines test and measurement dept. Measuring/recording/analysing things such as Strain guages, vibration, noise, pressure, temps, rotational speed, torque, flow, displacement, tip timing, x Ray etc etc. Maintaining signal integrity and minimising noise for the most part requires balanced (differential) amp systems/signal conditioning.

    https://en.m.wikipedia.org/wiki/Instrumentation_amplifier
     
    The Chronicals likes this.
  3. SteveG

    SteveG pfm Member

    Well that's the A840C here and wired on on both balanced and unbalanced connections. Obviously not intending doing any critical listening yet (not least 'cause it's currently just sitting on top of my CD3.5 so need to sort the rack set-up out) however one thing that is very noticeable is that it's a lot louder on the balanced connection compared to unbalanced. I'll need to figure out how much I need to adjust the volume to even that out.

    Got some more playing to do with the A840C as well 'cause I've realised I can run the optical output from my Chromecast Audio into it as an input, to replace the cheap Argos DAC that's currently using. It'll be interesting to see if all the upsampling etc. from that route will make a noticeable difference. The first impression of the 840C is that it sounds pretty good with CD's.
     
    John Phillips likes this.
  4. Arkless Electronics

    Arkless Electronics Trade: Amp design and repairs.

    I am not arguing that balanced is not a more robust method of signal transfer. What I am saying is that in a typical domestic hi fi it doesn't need to be particularly robust as we are talking short cable runs under conditions we can control and that it is therefore a "hammer to crack a walnut".

    I've been head of a calibration lab which dealt with most of the things you mention above but most of my career has been in audio electronics. I was Chief Engineer with Alchemist Products and an engineer with Musical Fidelity as specifically hi fi jobs but have worked in various sectors of the electronics industry, mainly audio or audio related, but also some in RF.
    I've designed measuring amplifiers (both balanced and unbalanced), reverse RIAA generators, low distortion oscillators, fast rise time square wave generators, a magnetic flux measurement unit for AFILS incorporating a pink noise generator, test jig for the later, a CCS dynamic impedance and noise test set (balanced), measuring mic pre amp (with calibrated gain, switchable A weighting, built in metering as well as line out), bench PSU's, capacitor ESR meter amongst other things.

    It is easy to name specific sectors in instrumentation that due to their nature will almost always use balanced somewhere, mainly as a front end amplifier... as it is also easy to name other types of test gear that generally don't use balanced...
     
    March Audio likes this.
  5. Woodface

    Woodface pfm Member

    Is this like a face off, has Jez met his match? ;)
     
    The Chronicals likes this.
  6. Dowser

    Dowser Learning to bodge again..

    I run a Mark Levinson No. 29 as a power amp during summer on environmental grounds - that means my preferred DIY SE valve hybrids generate too much heat in summer...

    The ML only has balanced inputs, and I’ve always used it with SE pre-amps and a cable just using one hot pin on the balanced input. It still sounds pretty good to me this way - but why did ML only offer balanced inputs? I assume design topology?
     
  7. clivem2

    clivem2 pfm Member

    Handbags....
     
    The Chronicals likes this.
  8. Arkless Electronics

    Arkless Electronics Trade: Amp design and repairs.

    I'm merely presenting the case for the defence of unbalanced in the specific context of domestic hi fi folks...
    March has chosen the balanced route, and like any manufacturer, having chosen a particular feature which can be used as a selling point he's not likely to give it "well yeah it probably makes no difference for most users":)

    There are at the upper echelons of domestic hi fi many examples of excellent kit which are balanced and many that are unbalanced!

    I guess if I have an "issue" with balanced it is merely that companies that have chosen this route usually either say outright, or imply, that it is intrinsically better and will use this as a selling point and to justify a sometimes higher price. This kind of thing spreads in Chinese whisper style until on forums etc we get basically "balanced is always much better than unbalanced innit... any fule kno that" when it is simply not true. All depends on topology and implementation like anything in audio electronics.

    I have no axe to grind with March and have enjoyed an obviously skilful engineer joining the good fight against bollox and foo:)
     
  9. SteveG

    SteveG pfm Member

    From what I've heard so far it's going to be very difficult to compare balanced via unbalanced in this system as the difference in volume is not trivial. I'll dig out the sound meter and see just how big the difference is, however it's much more noticeable that I'd expected.

    First impressions though are that the 840C is better than the CD3.5/Flatcap and I already find the Krell KAV-400xi better than the 32.5/SNAPS/140 that I was previously using. So my study system is sounding better than it ever has, although definitely need to find some speakers that are a better match to the Krell in a small room.
     
  10. sq225917

    sq225917 situation engineer

    Richard, probably to save on plugs. And maybe tie in with their other kit, a la naim.
     
  11. Arkless Electronics

    Arkless Electronics Trade: Amp design and repairs.

    I've had a gander and it's a differential input amp of relatively straightforward design which uses the "+ & - " inputs of a Long Tailed Pair (LTP) as you would expect BUT has an idiosyncrasy in that the "-" input goes via a discrete push pull buffer amp (to give a low impedance at the - input of the LTP so the output of the buffer can be "0V" to the NFB), whereas the "+" input goes directly to the LTP so has a shorter signal path. The phono input does go to the "+" input. To "gild the lilly", an XLR plug with a short from "-" to ground could be plugged into the balanced input whilst the phono input is in use. I doubt it will make much difference though!
    It is not really all that suitable for use with a passive as it has 1500pF at the input filter! If you have sources that will easily drive a 10K passive that is the highest value that should be used with it. It will work with a 50K passive but -3dB @ 8.5KHz at mid volume!
     
  12. Tony L

    Tony L Administrator

    Because the single-ended ‘not quite RCA plugs, but not quite anything else’ they offered at the time drove everyone absolutely nuts?!

    PS I’ve always fancied one of those ‘proper’ Mark Levinson pre/power combos, but those comedy plugs put me right off and I’d not want to bodge collectable/valuable kit such as that! You can occasionally find ‘ML Weirdplug’to RCA adapters, but they are about £100 each!
     
  13. Woodface

    Woodface pfm Member

    I 100% agree BTW. The irony being that a lot of pro kit is relatively affordable compared to domestic hi-fi.
     
    Arkless Electronics likes this.
  14. chainrule

    chainrule gordon

    I asked a fairly well known US electronics manufacturer why his new upper end pre-amp was balanced even though his amps were single ended. He said, "because that's what the market demands."

    No, I'm not naming names.
     
    Arkless Electronics likes this.
  15. Paul R

    Paul R pfm Member

    Balanced inputs and outputs necessarily involve more complication than single ended. Struggling to see where you're going with this.

    And the fact that there is crazier bollocks doesn't excuse the generalisation of a topology that has a purpose into a hifi must have.

    (My DAC has an intrinsically balanced output and an extra stage to drive the phonos. My ATCs have a single opamp buffer connected to an XLR. Most often nowadays the ATCs are connected to a single ended output on an AV amp. Rules are for fools.)

    I'm seriously considering balancing the output impedances on the AV amp by the simple addition of an appropriate resistor between 0v and the cold wire to the loudspeaker. I could choose the value by ear...
     
  16. martin clark

    martin clark pinko bodger

    Esp when it is so often, done so badly - the only real point of 'balanced' inputs is enhanced CMRR via balancing input impedances, yet there are no shortage of approaches inc implementations of the classic 3-opamp version, where one leg is about 9.9ish X the impedance of the other, destroying any putative benefit. Even Bryston suffered from this for a while.
     
  17. SteveG

    SteveG pfm Member

    So far I can confirm that there is certainly nothing wrong with the balanced option. It's going to take bit more work to compare it to the unbalanced inputs though, due to the difference in levels.

    I've been listening for a few hours now but have been sidetracked by just how good the Chromecast Audio sounds when fed into one of the 840C's optical inputs and then upscaled to 24/384 (then using the balanced input to the amp). It's been a bit of an eye opener really, as it's the first time I've really liked a streaming option - including hearing streaming options when demoing at dealers.

    I've been working through the malts as well - started on a nice 16 year old Lagavulin but have now switched to Caol Ila.
     
  18. martin clark

    martin clark pinko bodger

    Caol Ila FTW!

    (And yes, a Chromecast is a darn good little bit of kit.)
     
  19. SteveG

    SteveG pfm Member

    One of my favourite malts, but then I like them peaty!

    I'm going to buy several more and add them to all of our systems.
     
  20. March Audio

    March Audio Trade: March Audio

    From a user perspective, which was the point, there is just a different cable. No complication at all.

    That last bit was a joke right?
     

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