Help: Bi-wiring and cable thickness?

[Exophile]

Trying to wrap my head around bi-wiring and speaker cable thickness/gauge. I am getting a Rotel RA1572 with A and B speaker outs, and want to connect B&W 705S2 to it. Bi-wiring seems to offer advantages with clarity of sound.

With single wire (A channel only), I would guess that a gauge ~10 (2.5 mm diameter) would be OK. With bi-wiring (LF on A channel, HF on B channel), should I run two gauge ~10 cables to each speaker so total of 5 mm Cu, or could I also use a dual gauge 16 (1.3 mm), so total of 2.6 mm. Gauge 16 on its own is be a bit thin, but doubling up would correspond to a gauge 10 wire. Or split the difference in middle and go for gauge 14 (2x 1.6 mm = 3.2 mm = gauge 8)?

[Mixc]

Hi, the gauge of cable required depends on length of run, Longer run = Thicker cable.
There are a lot of factors to consider when choosing cables material purity and manufactureing process are a couple.
Also have a read of some articles relating to "The Skin effect" this may influence your decision.

Mick

[Exophile]

Thanks Mixc. My question is not about speaker cables in general, but it is an "all other things being equal" can I cut speaker cable diameter in half when bi-wiring a single speaker, or not, and why. I can see both arguments to be made, but don't know which is correct and why.

[Mixc]

Hi, The best route in most cases is to decide what you are trying to achive and work backward from that.
I think in your case as you are splitting the output from a stereo amp using the A/B, It wont make that much difference using the bi-wire option.
Bi-wire from a stereo amp gives you the oportunity to tune the sound by using different types of cable, Or reduce resistance by using thicker cable.
(I would use silver plated for the mid/top and high grade copper for the low)

To answer your question."can I cut speaker cable diameter in half when bi-wiring a single speaker"
In my opinion, as long as you consider, the current flow for the bass will be higher than the for the mid/top, Yes.
I would not suggest a 50/50 split if you are already on the lower limit of the required diameter.

Mick

[Audio Al]

I think you will find option A and B are for different pairs of speakers , so you can switch between pair A then chang over to pair B

Not sure what will happen if you try running A and B at the same time into 1 pair of speakers , it may get smoky and exspencive :eek:

[Stryder5]

I think your overcomplicating things buy decent speaker cable and use the same cable to both tweeter and bass.

I'm a believer in bi-wiring, others say they can't hear a difference.

I'm unfamiliar with cables available over there.

But Talk 3 and Fisual cables are good.

Gary


Trying to wrap my head around bi-wiring and speaker cable thickness/gauge. I am getting a Rotel RA1572 with A and B speaker outs, and want to connect B&W 705S2 to it. Bi-wiring seems to offer advantages with clarity of sound.

With single wire (A channel only), I would guess that a gauge ~10 (2.5 mm diameter) would be OK. With bi-wiring (LF on A channel, HF on B channel), should I run two gauge ~10 cables to each speaker so total of 5 mm Cu, or could I also use a dual gauge 16 (1.3 mm), so total of 2.6 mm. Gauge 16 on its own is be a bit thin, but doubling up would correspond to a gauge 10 wire. Or split the difference in middle and go for gauge 14 (2x 1.6 mm = 3.2 mm = gauge 8)?

[KindOfDaz]

With bi-wiring (LF on A channel, HF on B channel)

Any particular preference for this? I mean low frequencies on A, and not B?

[Mixc]

Any particular preference for this? I mean low frequencies on A, and not B?

Prob best to use "B" for bass. :)

[Exophile]

Thanks for all the pointers. I am aware that bi-wiring is not universally accepted as making a difference. The speakers have two pairs of binding posts, so no issues with shorting/smoking any equipment, if properly done, of course.

Thanks for the higher LF current consideration. Any idea on current distribution between LF and HF? 60/40 or 90/10?

Tuning with different cable types sounds intriguing, but not sure I will start off there. Re A vs B for LF/HF, I don't think it makes a difference. B for Bass has a certain logic :-)

[Ali Tait]

Al is correct. DO NOT use both sets of speaker outputs unless you are certain the speaker you are using does not dip below 8 ohms impedance at any point in it’s frequency response or you will most likely damage the amp. If you want to biwire, run both sets from the same speaker outputs.

[DiveDeepDog]

Some speakers like solid core cable, such as Audioquest. You could try solid core mains cable for a low cost trail? If that doesn't make any difference I'd be inclined to put the links in place and forget about cables...

I'm not a disbeliever, just more important things to consider when Van Damme just works :lol:

*Be aware there's fake AQ cable on eBay, I bought some Type6, the seller was very quick to refund !

[Mixc]

Any idea on current distribution between LF and HF? 60/40 or 90/10?

Tuning with different cable types sounds intriguing, but not sure I will start off there. Re A vs B for LF/HF, I don't think it makes a difference. B for Bass has a certain logic :-)

The percent split would depend on music content, Drum and bass vs piccolo solo..

I would say bi-wire has merit in certain circumstance but not always.
There is no harm in trying different combinations and see which suits your ears and budget, You can pick up top quality second hand cable on ebay easily.
I am using engineered cable and it suits me very well.

I hope it works out. Mick

[Stryder5]

Just realised this could be misread, I meant two lengths of the same cable to each speaker.



I think your overcomplicating things buy decent speaker cable and use the same cable to both tweeter and bass.

I'm a believer in bi-wiring, others say they can't hear a difference.

I'm unfamiliar with cables available over there.

But Talk 3 and Fisual cables are good.

Gary

[Pieoftheday]

Trying to wrap my head around bi-wiring and speaker cable thickness/gauge. I am getting a Rotel RA1572 with A and B speaker outs, and want to connect B&W 705S2 to it. Bi-wiring seems to offer advantages with clarity of sound.

With single wire (A channel only), I would guess that a gauge ~10 (2.5 mm diameter) would be OK. With bi-wiring (LF on A channel, HF on B channel), should I run two gauge ~10 cables to each speaker so total of 5 mm Cu, or could I also use a dual gauge 16 (1.3 mm), so total of 2.6 mm. Gauge 16 on its own is be a bit thin, but doubling up would correspond to a gauge 10 wire. Or split the difference in middle and go for gauge 14 (2x 1.6 mm = 3.2 mm = gauge 8)?

A and B speaker outputs are for two sets of speakers not biwiring. So your cable should go from set A or set B.so your speaker cable if bi wire should have two connections amp end and four connections speaker end:)

[Edward]

Tried buy-wiring at various times and did not notice much if any difference other than having to bi more speaker cable. Noticed a big difference buying better quality speaker cable in the first place. But YMMV.

Also speaker manufacturers spend a lot of time/money implementing decent cross-overs for single wire use. It seems perverse to partly defeat such crossovers with bi-wiring.

I did read somewhere that when using speakers that have bi-wire posts but when you only use normal single wire cable it is best to use the + (red) on the HF input and the - (black) on the LF side (obviously with links installed). There is probably some science behind that but I don't notice any difference (compared to say just using the HF).

[Barry]

A lot of speaker manufacturers make provision for bi-wiring, simply because it is fashionable and now expected by 'knowledgeable' customers. Advantages conferred through bi-wiring speakers will depend very much on the speaker itself as well as the amplifier used to drive it.

As to the gauge of wire used, well the usual rule of thumb is to choose a cable such that the loop resistance is no more than 5% of the nominal speaker impedance. So it depends on the length of the run, but in general "the thicker the better".

https://theartofsound.net/forum/showthread.php?5818-Basics-amp-General-Bi-amping-and-Bi-wiring

[losepete]

Looking at Audioquest Ft-4 and Rockett88 biwire cables here there are 2 different diameters of wire in use. The thinner wire is approximately 2/3rds the diameter of the thicker wire - Sorry, no way of measuring exactly.

I can tell you that when a friend tried the FT-4 cable in his system he managed to connect thinner wire to bass and thicker to tweeter. This resulted in a light bass with too much treble. Reversing his wiring improved things considerably :-)

If looking to try solid core biwire cable for less than half price - and if 2.3m length is long enough - you may want to consider the FT-4 cable I am offering here https://theartofsound.net/forum/showthread.php?59525-FS-Audioquest-FT-4-and-F-14-speaker-cable

[steve-z]

I decided to bi-wire my speakers after reading a write up on the Q Acoustics website which measured the intermodulation distortion levels comparing single and bi-wire configurations. Results showed a very significant drop in IM distortion in the line to the tweeter and a smaller but measurable drop in the line to the bass.
I use Audioquest FLX SLiP 14/4 cable on both my sets of speakers and get very good results, compared to just a single run of their 14/2 cable there is a noticeable improvement in clarity and “air” in the treble, for the small extra outlay it’s well worth doing. I use 2M lengths per side but the gauge of the cable would probably be fine for longer runs.


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[Exophile]

I sent an inquiry to Rotel re damage of amp if bi-wiring. As they are working closely with B&W, they should have a good answer. Haven't heard back yet ...

1/3 - 2/3 HF - LF split sounds reasonable. Interesting that there is wire explicitly made for bi-wiring. Have to look at that. Was initially thinking of using a 4x AWG 14 cable.

5% of speaker resistance for cable resistance, that would permit for some very long cable runs! For 8 ohm speakers that would be 400 milliohm resistance, so 50 m / 150 ft for AWG 14 wire! Even if I reduce that by 1/3 for LF, then I still have 100 ft of run.

[losepete]

The RA1572 manual shows:-

Speaker Selection
If only one set of speakers will be used at any given time, the speakers may
have an impedance as low as 4 ohms. If there are times when both the A
and B speakers will be used, all the speakers should have an impedance
of 8 ohms or more. Speaker impedance ratings are less than precise. In
practice, very few loudspeakers will present any problems for the RA‑1572.

So, Yes, you should be able to bi-wire using both sets of speaker outputs if speakers are 8ohms.

You can use bi-wiring with amps and speakers that only have 1 set of outputs/inputs and often increase your musical enjoyment as a result :-)

[Macca]

I would not bi-wire. Get a decent set of jumpers ( spend £50 tops) and use the thickest multi-strand copper cable you can get, single run into the bass terminals. Connect the jumpers between the bass terminals and the hf terminals and you're good to go.

[Macca]

Modern B&W are never an easy load so I would not recommend using both A and B speaker outputs at the same time. The amp will shut down or blow a fuse. Been there, done that, as have countless people.

[Barry]

5% of speaker resistance for cable resistance, that would permit for some very long cable runs! For 8 ohm speakers that would be 400 milliohm resistance, so 50 m / 150 ft for AWG 14 wire! Even if I reduce that by 1/3 for LF, then I still have 100 ft of run.

Not quite - the loop resistance should be no more than 5% of the nominal speaker impedance; that is the combined resistance of both wires. A figure of 5% is chosen so the damping factor is not reduced to less than about 20. So a loop resistance of no more than 400 mOhm implies a speaker cable length of no more than 78 ft, if the two wires are AGW 14. Still pretty long for a speaker cable; but up to a couple of years ago my speaker cables were 50 ft in length.

https://www.cirris.com/learning-center/calculators/133-wire-resistance-calculator-table