Do I need balanced connections?

Discussion in 'Hi-Fi Stereo Systems & Separates' started by dazed&confused, Feb 28, 2014.

  1. dazed&confused

    dazed&confused
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    Hi guys

    I am probably be going to be using separate pre and power amps in my stereo set up. My sources are on the other side of the room from my speakers, about 18 to 20 foot from the right speaker and about 12 to 14 feet from the left. I was thinking of having the preamp located next to my sources and the power amp closer to the speakers, so that it is tucked out of eye view and so that I can keep speaker cables short. The problem is that only one of the two pre-amps I am considering has balanced outputs, and many power amps don't have them. I could also tuck the power amp out of eye view by keeping it close to the sources, or I could move the preamp close to the speakers.

    I would be very interested in your views and recommendations regarding the following options, and which if any would require balanced cables:

    1) Long run of speaker cables from power amp to speakers
    2) Long run of interconnects from preamp to power amp
    3) Long run of interconnects from source to preamp.

    By long run, lets say 20 feet for speaker cable and 16 foot for interconnects. My guess is that a long run from the sources to the preamp would be problematic without balanced cables but I'm very unsure of the difference between the other two options.

    Many thanks...
     
  2. BlueWizard

    BlueWizard
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    I think the simplest and most economical method is to simply run long speaker wires, though 20 feet is not prohibitively long. Problems with speaker wire don't occur until the lengths start to approach 50 feet.

    On the Bowers-Wilkins 800 Diamond series, the recommend a maximum wire impedance of about 0.1 ohms. Keeping in mind the impedance on this series can drop as low as 3.0 ohms. Under the worst case 3 ohm circumstance 0.1 ohms would be about 3%.

    Typically it is recommended that the speaker wire resistance not exceed about 1% to 2% of the nominal impedance of the speaker.

    It is very difficult to find wire specification charts on Euro wire, but you can easily find spec charts on AWG (American Wire Gauge) wire, and find the nearest equivalent.

    American wire gauge - Wikipedia, the free encyclopedia

    For example, relative to the common 2.5mm² Euro wire, the nearest equivalent is 13ga AWG which has a cross sectional area of 2.62mm². The same 13ga wire has 2.003 ohms per thousand feet of wire. Consequently, 10 feet of wire would be 0.02 ohms. Multiply that by 2.5 to get 25 feet and the resistance is 0.05 ohms. If we assume 4 ohm nominal speakers, that is only 1.25%. To 8 ohms speakers it is a modest 0.625%.

    In short 25 feet of 2.5mm² wire is not going to be a problem.

    I'm not sure what the maximum distance is for standard RCA-style unbalanced cable. I would guess in the range of 10ft to 15ft. Though I have seen longer.

    Balanced Line, on the other hand, can be quite long. Think of a Rock Concert. The Balanced Microphone lines have to run all the way from the performer to the mixing console. That is typically a considerable distance.

    An unbalanced line is made up of a Signal and a Ground. The Signal line, when it gets too long, or when it is poorly sheilded acts as an antenna and picks up stray signals in the air, which are then sent to the amp to be amplified. I think I've used two 1 meter RCA cable chained together, for a total distance of 2 meter, or about 6.5 feet, and not had noise problems. It probably gets down to the quality of shielding. Ultra-cheap cables have about 10% shield coverage. Even 20% to 50% coverage is common. Quality cables have 90% or more shield coverage.

    A Balanced line has two floating signal lines, Signal(+) and Signal(-) which feed a balance differential input. These two signal lines are combined with a third Shield Earth Ground wire. Both signal inputs of the differential input are floating, and there in lies the advantage. While both signal lines pick up noise, the lines are opposite polarity. So for illustration, if each line picks up 2 volts of stray signal, that is +2v and -2v. Plus 2 and Minus 2 equal ZERO. The Balanced lines tend to cancel out any noise that is not signal, so you can have much longer runs of balanced lines. I would guess that 100 feet would not be uncommon.

    You can have a reasonable distance between the Pre-Amp and power amps assuming your room has a preferred location for the power amps. This distance can be reasonably long if you use Balanced connections, and it can be modestly long with unbalanced lines.

    Source to Pre-amp runs are similar with perhaps the exception of a turntable. A turntable needs about 100 times more amplification than a typical Line Level signal. If the Turntable wires pick up noise that noise is going to be amplified by a factor of about 100. The Turntable lines need to be reasonably short and well shielded. I would guess UNDER 10 feet of high quality fully shielded wire for the turntable.

    However, while various combinations of wire and cable lengths are possible, a simply run of 25 feet or less of common 2.5mm² speaker wire is well within the realm of workability, as I have illustrated above. No need to make a simple problem complicated. However, that said, you do have some flexibility in the placement of the Source relative to the Pre-Amp and the Pre-Amp relative to the Power Amp. But that flexibility should be for practical placement reason, not an attempt to shorten the speaker wire simply to shorten the speaker wire.

    For what it is worth.

    Steve/bluewizard
     
  3. dazed&confused

    dazed&confused
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    Thanks Steve for yet another clear and comprehensive reply

    [quote="you do have some flexibility in the placement of the Source relative to the Pre-Amp and the Pre-Amp relative to the Power Amp. But that flexibility should be for practical placement reason, not an attempt to shorten the speaker wire simply to shorten the speaker wire.[/quote]

    My initial idea was indeed to try to keep the speaker cable short, and if I'm totally honest to justify using balanced cables just because one of the amps I was looking at happened to have them, LOL. Plus it so happened that if I moved the power amp closer to the speakers, there was a neat place to stash it away out of site and thus keep the apparent presence of ugly boxes to a minimum. Believe it or not, a dealer told me that I would get more benefit from better speaker cable than I would from a better DAC. I begrudged the idea of spending so much on simple wire and somehow told myself it was ok so long as I kept the lengths short. Having read some of the thread on speaker cable, and realising that the What HiFi reviews were indeed ridiculous, I think I will stick with decent quality 2.5mm cable or thereabouts.
     
  4. Trollslayer

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    As ever Steve, spot on.
     
  5. BlueWizard

    BlueWizard
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    If you want to start a fire, or more likely start a flame war, then start a discussion about Speaker Wire.

    There are three schools of thought on this -

    1.) Wire is wire, get good quality but low cost wire of sufficient size for your needs. While I use pretty basic low cost wire on my modestly priced system, I do see some value in better speaker wire sometimes.

    2.) Get wire in proportion to your system cost. This is the general camp that I'm in when I make recommendations. If you can afford an expensive system, then you can afford some expensive wire. Generally, I would say in the range of 2% to 5% of the total cost of the system on ALL Cable and Wire.

    3.) Get the most expensive cable you can possibly afford. Though in all honesty, this is the opinion held by people selling expensive wire and cable.

    Generally, individual wire and cables should be under 3-digits, meaning under a £100. Depending on the circumstances, most would be in the mid-2-digit range, though on rare occasion, one might go just above 3-digits. Though I assure you many cringe at the idea of more rising above 3-digits. But, in another discussion, someone provided a link to a 10ft speaker wire pair that was ON SALE for US$25,000/pr. No that is not a misprint, I said US$25,000/pr. US$25,000 speaker wires are God's way of telling you, you have too much money.

    Here are a couple of examples of heavy duty but generally straight forward speaker wire. Fisual Super Pearl 2.5mm² -

    Fisual Super Pearl 2.5mm Speaker Cable - Black - Speaker Cables - AudioVisual Online - Home Cinema and Hifi Specialists

    Fisual Super Pearl 2.5mm Speaker Cable - White - Speaker Cables - AudioVisual Online - Home Cinema and Hifi Specialists

    If you enlarge the pictures, you will see that is is two wires wrapped in colored insulation, then again wrapped in a second layer of black (or white) insulation. This double insulation can make the wire a bit stiff.

    Another popular speaker wire is the Van Damme Studio Blue 2.5mm² -

    Van Damme Studio Grade Blue Speaker Cable 2.5mm - Speaker Cables - AudioVisual Online - Home Cinema and Hifi Specialists

    Again, double insulated, but this time, two individually insulated wires both wrapped in a single second layer of insulation. This still more stiff than common twin-lead, but not quite as stiff as the Fisual Super Pearl 2.5mm².

    In common twin-lead, which is more compact and flexible, something like the QED 79 Strand (2.5mm²) -

    QED 79 Strand Speaker Cable - Speaker Cables - AudioVisual Online - Home Cinema and Hifi Specialists

    Keep in mind if you buy in bulk lengths, you can cut the price of Twin-Lead to about half what the 79 Strand costs.

    If we take the Fisual Super Pearl expand it to a common length of 3 meters, and terminate the ends with quality Banana plug, the total cost of that wire would be £18.60 each.

    If we do the same with the Van Damme Studio Blue, 3 Meters, Banana plugs on both ends, the total is £22.20 each.

    Now, if you really want to go nuts, there are certainly plenty of choices under the moon -

    Audioquest Cinemaquest, 3M, banana plugs both ends = £82.00 each
    Audioquest CinemaQuest Type-4 Speaker Cable - Performance Speaker Cable - AudioVisual Online - Home Cinema and Hifi Specialists

    QED X-Tube XT-300, 2 x 3.0mm² conductors, 3m, 4x AirLock banana plugs = £51.38 each -
    QED X-Tube XT-300 Speaker Cable - Speaker Cables - AudioVisual Online - Home Cinema and Hifi Specialists

    QED X-Tube XT-400, 2 x 4.00mm² conductors, 3m 4x AirLock banana plugs = £105 each -
    QED X-Tube XT-400 Speaker Cable - Speaker Cables - AudioVisual Online - Home Cinema and Hifi Specialists

    Being in the second catagory of equipment in proportion to your system cost, I would have to know what system you have and what it cost to make a judgement.

    Most people are in the catagory that says - don't believe the hype. Yes, if you want some nice looking quality speaker wire, that's your choice. But I think, unless you have massively expensive system, most people would be happy in the price range of the Van Damme Studio Blue wire.

    Also note, the demands on the Front Speakers (Left/Center/Right) of a Surround Sound system are pretty high and the runs are pretty short. One could put higher quality cable on the Front Three speakers. On the longer runs to the less demanding Side/Rear speakers, common twin-lead would be fine.

    That said, myself, I use bulk wire of good quality Oxygen Free Twin-Lead 2.0mm² (actually AWG 14ga) that costs less than £1/meter.

    Steve/bluewizard
     
  6. dazed&confused

    dazed&confused
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    Thanks Steve.

    I will check out some of the links when I get around to replacing my speaker cable.
     

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