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Which cables to leave long, speakers or XLR?


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28 replies to this topic

#1 of 29 George Kouzev

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Posted May 01 2003 - 08:35 AM

Once I upgrade to my new system and move stuff around I will have to increase the speaker cable length from 14' to 30'. I have a pair of Mirages M5, using bi-wire Audioquest.

Should I have a good quality 30' speaker cable, or try to move the future Bryston amp close to the speakers and have 25' good quality XLR interconnects between the pre amp and the amp?

GK

#2 of 29 Philip Hamm

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Posted May 01 2003 - 08:59 AM

NO QUESTION go with long XLRs. Others may be able to explain why. XLRs are isolated and grounded specifically for the purpose of handling long runs silently; speaker cables aren't.

This may be a better question for the Tweaking forum. I hoe you don't mind I'm going to recommend that it get moved there.
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#3 of 29 JamesDB

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Posted May 01 2003 - 09:06 AM

You should use the XLR cables for long runs, and the amp to speaker higher-current cables as short as possible. This is because the XLR balanced cables are designed as a two way signal that cancels external interferance which can be picked up by long cable runs. Cables running higher current will usually tend to amplify greatly these external signals giving you impurity in your sound (ie taxi cab CB radio, or simple fuzz).

Another common misconception some people have is that one should turn the amp (can be in the subwoofer too) all the way up and correct the signal (turn it down) in the receiver or preamp. In reality it's the other way around. Try to send the strongest (reasonably strongest due to headroom) signal from your receiver/preamp to the amp, and only turn the amps up as much as you need with calibration. Again this is to maximize the signal to noise ratio. Noise floors become increasingly strong as elements are added to the chain.

Although in many home stereo settings you might not notice huge improvements from doing the latter, all professional sound engineers (I run sound for large concerts, but recording industry is the same) benefit greatly from this.

Hope this helps

#4 of 29 Chu Gai

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Posted May 01 2003 - 09:17 AM

and unless one get's silly, long XLR runs aren't that expensive.

#5 of 29 RobWil

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Posted May 01 2003 - 09:50 AM

Quote:
Another common misconception some people have is that one should turn the amp (can be in the subwoofer too) all the way up and correct the signal (turn it down) in the receiver or preamp.


Is that amp dependant possibly because in the manual for my Audiosource Amp One (external amp) it specifically says that they recommend turning the amps controls all the way up and using the volume control on the pre-amp/receiver.

Also...me being a dumbass and all....what are XLR cables?
I get that they're interconnects between the pre-amp and the external amp, but are they specific types of cables?
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#6 of 29 JamesDB

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Posted May 01 2003 - 12:35 PM

Hey Rob,

I was thinking about your question since I admit there are some caveats to my statement due to the fact that this is home audio. For instance I have a Denon 3803 at home and if one raised the signal strength at the preamp stage past the 0, it subtracts it from the total gain available on the dial (although denon claims that it is not actually lost). Additionally in home audio there is nothing to show you if your signal is too hot and reaching the headroom of the circuits thereby clipping at preamp stage. So there may be some tradeoff to consider.

However in your situation I still stand by my statement. Noise is added to your "pure" signal at many stages in your chain. For example your DVD player send the pure original signal to your preamp. If it's an analog signal the first noise is added on the line between the two. Your preamp then sends it down a wire to your main amp. Here again noise is added both in the preamp circuitry and the line. Then it is amplified to high current and goes to your speakers where noise is added in the amp circuitry and the high current line.
If you can have the most relative amplification as early as possible down your chain you amplify at the best signal to noise ratio location. Therefore by the end you have amplified the least amount of noise into your signal.

One caveat. Since each item in your chain will add noise, only amplify later in your chain if you are certain that the later item's tolerences are so much better than the previous items that it offsets its position. For instance if you have a crappy preamp with nasty circuits that create lots of noise and a really hot expensive amp that is super clean and transparent then by all means amplify more on the amp stage. But most of us have pretty balanced level of equipement on our chain.

BTW, noise is added due to many things such as EM radiation ie. CB radio (which XLR is good at shielding out), lighting, ground loop, microwaves etc. so sometimes changing those nasty 60Hz florescents, or high power spot lights can really help. In pro audio its probably our major challenges.. balancing the lighing companies needs and sound needs.

As far as XLR is concerned its mainly different than your typical RCA in that it is balanced (it carries the same signal in two directions resulting is negating noise that was picked up on the line or circuit). Usually XLR is also shielded using very tightly braided foil for additional quality. You need to have XLR connections (or TRS) to use balanced signals. Its available on some higher end home audio stuff like Lexicon, or you can pick up an RCA to XLR active convertor for it. Remember though that the convertor will itself add some noise so unless you have really long runs to your amp or live in an EM saturated environment it might not be worth it. Just keep your amp to speaker lines as short as possible and amplify early in your chain.

#7 of 29 RobWil

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Posted May 01 2003 - 01:18 PM

Thanks, James...appreciate the input Posted Image
You know...looking at your quote again ...
quote:
------------------------------------------------------------Another common misconception some people have is that one should turn the amp (can be in the subwoofer too) all the way up and correct the signal (turn it down) in the receiver or preamp.
------------------------------------------------------------
... I realized something. Not only do I have to turn the amp volume controls all the way up, but I also have to turn the volume control on the receiver up to the normal listening position, i.e. 9-10 o'clock. Unless I use the direct connect, CD to amp, I get no sound otherwise.

RE: the xlr cables....I'm assuming for short runs regular audio interconnects are OK? Does xlr stand for extra long run or something?

NOTE: George ....don't mean to hijack your thread, but it looks like your ? was answered. Let me know if this is inappropriate.
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#8 of 29 John Royster

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Posted May 01 2003 - 01:41 PM

I guess I'll chime in with my experience on source/pre-amp/amp.

Adjust the gain on your amp so that right before your pre-amp clips you'll be at maximum power (basically before the amp clips).

This is hard to explain but you can do it by ear...there comes a point where your pre-amp will start to clip and distort. You'll hear it. That's bad.

Turn the volume/gain on the pre-amp down a little to get max voltage from the pre-amp with no clipping and then bump up the amp gain right up to distortion/clipping.

now both pre-amp and amp are at the highest signal to noise ratio you can get them. pre-amp sending highest voltage it can without distortion, amplifier is amplfying it.

For the original question - XLR all the way.

#9 of 29 RobWil

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Posted May 01 2003 - 01:58 PM

Hmmmm.....this is a little over my head. I either have to turn the amp up all the way and then turn the preamp up to normal, or turn the amp up partially and then turn the preamp way past normal.
But back to the XLR......assuming I have an ext. amp for each channel , one 10 ft from the preamp and one 18ft...does the XLR cable length difference matter at all like speaker cable lengths? I'm guessing not.
Also...any preference over something like Canare L-4E6S as opposed to Belden 1800F?? Something better?
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#10 of 29 Wayne A. Pflughaupt

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Posted May 01 2003 - 02:52 PM

Quote:
Also...me being a dumbass and all....what are XLR cables? Does xlr stand for extra long run or something?
The simple answer, Rob, is they are the cables you typically see used for microphones. James gave a good response on how the circuitry works, although the signal topology is known as “balanced,” not XLR. That might not have been clear from James' post.

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#11 of 29 Chu Gai

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Posted May 01 2003 - 07:46 PM

of course it is entirely possible that the sum of all this distortion is still an order of magnitude or two below the threshold of audibility. 'course we don't worry about that when its tubes now Posted Image

#12 of 29 Brett DiMichele

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Posted May 01 2003 - 09:10 PM

LOL Chu,

Youn just had to go there huh Posted Image

Balanced Lines are the superior way to cary any signal but
in home audio you only find this in the upper echelon of
components. With short runs (1 to 6 foot) there generaly
is not any issue. And even if you were absorbing some EMI
from nearby wiring you could choke the internconnect with a
Ferrite Choke.

As has been stated you can convert any non balanced Phono
output to fully Balanced but you need an external conversion
box which in it's self will add some more noise. But if you
are running 30' of cable it may well be worth it.

BTW this is what an XLR Connector looks like for future
reference.


Female
Posted Image

Male
Posted Image
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#13 of 29 Chu Gai

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Posted May 02 2003 - 01:06 AM

heck i'm not slamming you Brett, but I do think you've been around your equipment too much when that's your idea of a female! well some of these boxes that you talk about use little bitty isolation transformers to effect the 'change' so they're essentially passive. also rather remarkable for actually cleaning up a signal.

#14 of 29 Philip Hamm

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Posted May 02 2003 - 02:45 AM

Quote:
well some of these boxes that you talk about use little bitty isolation transformers to effect the 'change' so they're essentially passive. also rather remarkable for actually cleaning up a signal.
You can say that again. My Ebtech hum eliminators are really something else!

BTW I'm pretty sure that Brett's right about Male/female on those XLR's. The three prongs are the conductors, and they are most obviously male and female.
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#15 of 29 RobWil

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Posted May 02 2003 - 05:05 AM

Quote:
BTW this is what an XLR Connector looks like for future


What do those plug into? The external device you were talking about?

Quote:
With short runs (1 to 6 foot) there generaly is not any issue

So what if I have a 10-15 ft run. Do you think I would benefit from balanced cables?
If not, what type of cables are best for amp to preamp connections? Just regular audio cables? Would the cable type alter the sound of the signal like a CD to preamp cable does or is it a different type of signal and cable type isn't that important?
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#16 of 29 JamesDB

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Posted May 02 2003 - 07:55 AM

Quote:
well some of these boxes that you talk about use little bitty isolation transformers to effect the 'change' so they're essentially passive. also rather remarkable for actually cleaning up a signal.


Just a small note here. Those passive boxes are usually used for pro audio to pro audio conversions where dbu stays the same. Pro Audio runs at reference +4dbu whereas home audio is at -10 dbV. This is about a 11.8db difference when you convert and subtract. This means that true unbalanced home audio to true balanced pro audio conversion has to be active as in it required power input. One of the reasons that the +4 dbu is used is that it provides significantly better balance between signal to noise ratio and headroom available across the line. Also due to some physics laws that I don't claim to understand +4dbu has better EM / RF rejection that -10dbV. Of course this is all somewhat moot since these are just standards. For instance true Mic line levels are much much lower than even -10dbV hence the reason for expensive preamps that don't add noise.

So I guess you can use passive conversion, but you do have to make up for the signal at the amp later on,which will never have the pure amplification quality of a good preamp circuit. If you have a pro amp then that expects +4dbu better to give it the right signal strength in the first place.

#17 of 29 JamesDB

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Posted May 02 2003 - 08:45 AM

Hey John Royster

I agree with your input on how to calibrate the equipment on everything except turning the amp up to right before clipping. This is usually what we do at concerts since we want to blow people's ears out, shake the walls and floors to fracture point and therefore push the equipment to the limits Posted Image

But for home use I'd say just turn the amp up until you hit reference levels on your SPL meter. So turn your preamp to reference 0, maximize the signal to headroom with some CD that was recorded very hot to find your clipping point, and then turn up your amp slowly to reach reference SPL 105db or whatever you like. Then when you watch your movies you'll know that your 0 is where it should be and have kept your noise floor to a minimum.

Oh, I do like the Sonifex red box series of unbalanced to balanced convertors. A bit pricy but good stuff. I would use balanced for anything past 15 ft but it depends where I lived. For rural maybe one can go longer.

I have a question for everyone.

Do you guys really think that a normal shielded $20 RCA cable will really deliver crappier sound than a $150 monster cable? I just can't hear a major difference and I think my ears are not too bad.

#18 of 29 RobWil

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Posted May 02 2003 - 08:51 AM

Posted Image
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#19 of 29 Chu Gai

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Posted May 02 2003 - 09:22 AM

list your questions Rob...I'll see if I can give a more reasonable, detailed, answer later this evening. hang in there and have a beer.

#20 of 29 ChrisHeflen

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Posted May 02 2003 - 09:48 AM

I am in the same predicament. My equipment is far away from my speakers and tv. My runs are at least 30' and I like to bi-wire. I couldn't afford 100' of Audio Quest bi-wire cable or any other better than entry level cable. I am using Monst%$#$%er cable 4 conductor to bi-wire, but then a friend of mine said double up the wires and just use the jumpers on the speakers. This way I'd (my paraphrasing) have more current carrying capabilities. What do you guys think?
I can't move my amp and while my pre-pro is my amp is not balanced.

And sorry George if I'm budding in with my problems.


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