wire runs

[may29901]

I might put an amp in a space convenient but remote to the listener,that is me.
It would just be convenient. If I did I would have to run speaker wire 15 ft per speaker and a 10 ft cord to connect a pre amp so I could control it..didnt really want to use a pre but...
do you think these runs are do able??? I would only have access to the pre and the cd player and DAC. I assume I could connect a subwoofer to the pre also...??

 

[shelly_d]

I would put the power amp closer to the preamp so that the cabling run between them is 3 to 6 feet. Ten feet isn't too bad but as a general rule shorter is better. Speaker runs of 15 to 20 feet of cable is no problem at all. I would use 16 gauge wire for that.

Shelly_D

Connecting the subwoofer all depends upon the outputs of the preamp, the inputs of the subwoofer power amp and the subwoofer itself.

 

[4-2-7]

I would put the power amp closer to the preamp so that the cabling run between them is 3 to 6 feet. Ten feet isn't too bad but as a general rule shorter is better. Speaker runs of 15 to 20 feet of cable is no problem at all. I would use 16 gauge wire for that.

Shelly_D

Connecting the subwoofer all depends upon the outputs of the preamp, the inputs of the subwoofer power amp and the subwoofer itself.

Your kind of opposite it's best to have sort speaker cable runs.

If posibal use balanced XLR IC thay are designed for long runs.

When people run mono blocks they put them by the speaker with very sort cables and the long XLR to the pre fo SQ.

 

[4-2-7]

By the way it's always best to tell us what gear your asking about. Amp, Speakers,Preamp

 

[shelly_d]

Your kind of opposite it's best to have sort speaker cable runs.

If posibal use balanced XLR IC thay are designed for long runs.

When people run mono blocks they put them by the speaker with very sort cables and the long XLR to the pre fo SQ.

I have seen that stated many times. From an engineering standpoint I disagree with this. The signal from the power amp is to speakers is Much stronger then the one from preamp to power amp. Therefore it is much less likely to be degraded from external noise sources. Speaker runs are also less likely to roll off the high frequencies due to the cable capacitance reacting with the input impedance of the amp forming a low pass filter then an interconnect.

Shelly_D

 

[for_p1]

Get amp close to speakers. Use 12ga wire there. Consider that speaker cable should carry 30-50A of peak current. For the run between preamp and power amp over 6 feet you better use balanced interconnect (both pre- and power amp should support that).

 

[shelly_d]

Get amp close to speakers. Use 12ga wire there. Consider that speaker cable should carry 30-50A of peak current. For the run between preamp and power amp over 6 feet you better use balanced interconnect (both pre- and power amp should support that).

No where near that much current. Consider this: My 86dB sensitive speakers rarely draw as much as 5 watts on the meters. This suggsts the power will max out 10 dB higher (being that the meters are not fast enough to react to the peaks, only the average) at 50 Watts. (This is also loud enough to bring neighbors to my door).

The current at 50 watts comes from the formula:

Power = Current squared times Impedance. (I^2xR)

When R = 8 ohms and Power = 50 watts

then the current is

I = sqrt(50/8) = sqrt (6.25) = 2.5 amps.

Lets remember that this is the current at the peak power, (not rms) so there is no need to convert from RMS to Peak, but should you wish to believe that conversion is required, mulitply by 1.414. So 2.5 x 1.414 = 3.535 amps. So no, speaker wire does not regularly carry that much current.

Shelly_D


BTW: A current draw of 30 amps loaded into an 8 ohm speaker will be deliving 7.2 Kilowatts, or 7,200 watts. I know of no amp capable of delivering anywere near that much power.

Lets be real here folks.

Shelly_D

 

[Mark B]

I might put an amp in a space convenient but remote to the listener,that is me.
It would just be convenient. If I did I would have to run speaker wire 15 ft per speaker and a 10 ft cord to connect a pre amp so I could control it..didnt really want to use a pre but...
do you think these runs are do able??? I would only have access to the pre and the cd player and DAC. I assume I could connect a subwoofer to the pre also...??

Shouldn't be any problem doing this. I would use shielded IC's.

 

[for_p1]

No where near that much current. Consider this: My 86dB sensitive speakers rearly draw as much as 5 watts on the meters. This suggsts the power will max out 10 dB higher (being that the meters are not fast enough to react to the peaks, only the average) at 50 Watts. (This is also loud enough to bring neighbors to my door).

The current at 50 watts comes from the formula:

Power = Current squared times Impedance. (I^2xR)

When R = 8 ohms and Power = 50 watts

then the current is

I = sqrt(50/8) = sqrt (6.25) = 2.5 amps.

Lets remember that this is the current at the peak power, (not rms) so there is no need to convert from RMS to Peak, but should you wish to believe that conversion is required, mulitply by 1.414. So 2.5 x 1.414 = 3.535 amps. So no, speaker wire does not regularly carry that much current.

Shelly_D

Did you notice "peak"? If you run at 5W average, then peaks can be 20dB above that at 500W. Then add variation of speaker impedance where real load can be as low as 2 ohms. That is why 200W amplifiers are often rated 1000W at 1 ohm. 30 Amps = 900W at 1 ohm.

 

[shelly_d]

Did you notice "peak"? If you run at 5W average, then peaks can be 20dB above that at 500W. Then add variation of speaker impedance where real load can be as low as 2 ohms. That is why 200W amplifiers are often rated 1000W at 1 ohm. 30 Amps = 900W at 1 ohm.

Musical peaks tend to run about 10 dB above average, not 20 and with more modern releases (which are compressed much more then in the past) even less then that. Speaker variation may well be as varied as you suggest, dipping down to perhaps as low as 2 ohms in portions of the frequency range. However, not all the power being delivered into the speakers will fall into that very narrow frequency band and therefore nowhere near that much current will be drawn from the amp. I run a 200 watt amp into fairly inefficent speakers, often turning the volume up. That kind of current does not get pulled. The amp would surely clip if it did, or perhaps blow the output devices.

I stand by my calculations.

Believe what you will.

Shelly_D

By the way, my 35 watt per channel tube amp does almost as well as the 200 watt monster. The current is nowhere near that much.

 

[whoaru99]

FWIW, both Bryston and Levinson suggest shorter speaker cables and longer ICs vs. the other way around.

Because of the high impedance of the low level connection there is virtually no loss from series resistance. The low pass thing is hardly a consideration at any practical lengths being discussed here, and then some, unless you have really crappy cable, gear with exceptionally high output impedance, and a really big room. Even with a source impedance of say 600 ohms, cable capacitance of 100 pf/m, and length of 30m (all quite generous figures), the -3dB point is nearly 90kHz.

 

[Kingshead]

And one of the benefits to mono blocks and vertical bi-amping.

 

[whoaru99]

BTW: A current draw of 30 amps loaded into an 8 ohm speaker will be deliving 7.2 Kilowatts, or 7,200 watts. I know of no amp capable of delivering anywere near that much power.

Lets be real here folks.

Shelly_D

Perhaps not amps generally known as consumer audio amps, but there are pro amps in that neck of the woods or more. For just a couple examples the Lab Gruppen FP14000 is rated 8,800 watts @ 8 ohms bridged and the Powersoft K20 is rated 10,400 watts bridged @ 8.

 

[bobrown14]

My suggestion for a long run would be balanced XLR from pre to amp with short(er) speaker cable runs. I would use XLR for anything over say 6ft for signal runs. Whats a long speaker cable run anyways.. I don't think a long speaker cable run (20') would be any problem with regard to sound quality.
So 20ft + 20ft speaker cable run you're in a HUGE room there's going to be a lot more issues to deal with along with the cables. I think we are talking home use here?? I think the only real place a signal would degrade in a normal listening space will be the pre to amp connection if it was to be of any length. Sounds like the OP wants to sit close to the source with amps and speakers across the room/another room maybe home theater ??? If home theater then put the source in a closet with a IR remote, best of both worlds!

If the OP wants to listen to LPs and wants the TT and preamp next to listening position and everything else across the room... then its going to be XLR from pre to amp with TT next to the preamp. Nothing new....

Cheers,
Bob

 

[charles 1973]

For the most part you should have no problem running standard RCA preamp cables to 12' and speaker cables to 15'. Perhaps, if you are using $10,000 amps and $20,000 speakers, even then I don't see a problem.

I suggest using decent interlink cables for a 12' run though. I'm thinking Blue jeans cable quality or better...there not expensive. Speaker cables of 16 gauge lamp cord will do fine for up to 24' with 4 ohm speakers, 18 gauge for 8 ohm speakers.

 

[bowtie427ss]

I stand by my calculations.

Believe what you will.

Let's look at impedance alone.

You have two signal paths, one with a source of a fraction of an ohm to a few ohms, and a load of a few ohms.

The other has a source of several hundreds of ohms or more, and a load of likely several thousands of ohms.

Which path would you rather stack additional cable resistance(perhaps up to a few 10ths of an ohm) in?

I would also add that in terms of noise/interference rejection, interference and noise picked up by a 10-12 foot cable, is probably not going to be rejected by a 3 or 4 foot cable either.

 

[bobrown14]

I take back my recommendation of 6' as the max for an RCA signal cable run and dial that back to 3' or 1 meter, no longer. I did research. The shorter the signal wire the better unless you are running XLR (true XLR not RCA to XLR). Consumer gear with XLR are rare.

Going longer than 3' and you will very likely suffer from POOR THD, noise, frequency response, and crosstalk.

I read that from an engineer that was working with a Squeezebox Transporter running longer than 3' signal cable runs during testing. No science just real world experience. The only time I've ever run longer than 3' signal cables I used XLR with good result.

Actually the Transporter may be what the OP needs for long runs (it will eliminate those long cable runs) by using WIFI. No affiliation and never tried it either.

Cheers,
Bob

 

[JP]

Going longer than 3' and you will very likely suffer from POOR THD, noise, frequency response, and crosstalk.

I read that from an engineer that was working with a Squeezebox Transporter running longer than 3' signal cable runs during testing.

At line level? Did the engineer provide any data to back these rather spectacular claims?