Hi all,
I'm working on a set of 2-way active speakers. I was planning on building a separate amplifier/crossover chassis, and running 2 pars of speaker cables to each speaker, rather than power each speaker and run 1 signal cable. I always thought that long speaker cable runs were preferable to long signal runs because they were more resistant to noise and attenuation (being at a higher voltage). Plus I'll only need one power supply, and I don't have to plug my speakers in.
Now I am seeing opinions that are contrary to my thinking.
Considering that the eventual place for these speakers will be as surrounds in an HT setup, and that the cable runs will be around 40 feet, which would be the way to go? I have the parts to make a power supply for each speaker, which would be ridiculously over-spec'd for only one channel, but I'd like to save those for my next pair if I could.
Thanks, Dan
I'm working on a set of 2-way active speakers. I was planning on building a separate amplifier/crossover chassis, and running 2 pars of speaker cables to each speaker, rather than power each speaker and run 1 signal cable. I always thought that long speaker cable runs were preferable to long signal runs because they were more resistant to noise and attenuation (being at a higher voltage). Plus I'll only need one power supply, and I don't have to plug my speakers in.
Now I am seeing opinions that are contrary to my thinking.
Considering that the eventual place for these speakers will be as surrounds in an HT setup, and that the cable runs will be around 40 feet, which would be the way to go? I have the parts to make a power supply for each speaker, which would be ridiculously over-spec'd for only one channel, but I'd like to save those for my next pair if I could.
Thanks, Dan
Hi Dan.
In general you can ad the cable-impedance to the amplifiers output-impedance, and thereby get the system output impedance, wich you're using to calculate the damping-factor.
A 40 feet cable typically has a lot higher impedance than a typical amplifier output-impedance, and therefor ruins the dampingfactor.
In your case, though, driving a pair of rear surround-sound speakers, it is IMHO way overkill to make two separate amps. I'd recomend the long speakercables.
In general you can ad the cable-impedance to the amplifiers output-impedance, and thereby get the system output impedance, wich you're using to calculate the damping-factor.
A 40 feet cable typically has a lot higher impedance than a typical amplifier output-impedance, and therefor ruins the dampingfactor.
In your case, though, driving a pair of rear surround-sound speakers, it is IMHO way overkill to make two separate amps. I'd recomend the long speakercables.
Thanks for the replys.
FYI, these are going to be basically active "Dayton III's". My 16yo DIY main speakers have shredded their woofer surrounds, and rather than repair them, I'm going to make this new pair. They will be my main speakers until I can build the eventual main speakers, which will be active hybrid electrostatics.
Cheers, Dan
FYI, these are going to be basically active "Dayton III's". My 16yo DIY main speakers have shredded their woofer surrounds, and rather than repair them, I'm going to make this new pair. They will be my main speakers until I can build the eventual main speakers, which will be active hybrid electrostatics.
Cheers, Dan
Dan,
I'm in the same boat - thanks for posting your question.
I'm building a pair of H-frame open baffle woofers (2x Peerless 830500 for each of the rear channels) matched with a Manger transducer on top, and crossed at either 100Hz or 150Hz. I'd like to put the XO and both amps in the back of the room, running line level interconnects from the preamp about 25-30'. I want to do this primarily to keep the XO box and two amps out of my already over-flowing equipment rack, but would this be a bad idea? I've seen several others here (Hpotter, for one) placing amps as close to the speakers as possible. Does this somehow change with longer IC's?
BTW, without trying to start an exotic cable flame-a-thon (like the ongoing power cable debate on another thread) I'm thinking of riding the fence a bit by using moderately-priced, but still somewhat respectable cables until I have time to experiment further by building J. Risch's Belden 89259/89248 IC's and using T14 speaker cable. Any comments on problems with either of these cables in the proposed setup above?
thanks.
brad
I'm in the same boat - thanks for posting your question.
I'm building a pair of H-frame open baffle woofers (2x Peerless 830500 for each of the rear channels) matched with a Manger transducer on top, and crossed at either 100Hz or 150Hz. I'd like to put the XO and both amps in the back of the room, running line level interconnects from the preamp about 25-30'. I want to do this primarily to keep the XO box and two amps out of my already over-flowing equipment rack, but would this be a bad idea? I've seen several others here (Hpotter, for one) placing amps as close to the speakers as possible. Does this somehow change with longer IC's?
BTW, without trying to start an exotic cable flame-a-thon (like the ongoing power cable debate on another thread) I'm thinking of riding the fence a bit by using moderately-priced, but still somewhat respectable cables until I have time to experiment further by building J. Risch's Belden 89259/89248 IC's and using T14 speaker cable. Any comments on problems with either of these cables in the proposed setup above?
thanks.
brad
dc said:
Only one comment. IC is an abbreviation for integrated circuit.
If you must run long interconnect cables, use balanced lines. But you probably don't have balanced I/O on your preamp/power amp... Long interconnect cables are subject to noise pick-up which then gets amplified along with the audio being applied to the speakers.
Go with long speaker cables. Since there is no gain between the speaker and the amplifier, it is the best place for a long cable run.
If you're really worried about the cables affecting the sound, make some speaker cables out of twisted pair ribbon cable. besides the low inductance, they lay flat under carpet.
MR
sam9
It seems to me the most direct solution to noise in long runs of interconnects is balanced cables and XLR connectors. However, there is, it seems, only one right way to do this but mant wrong ways. Suggest taking a look at an article on this subject at www.rane.com. I think the topic is gounding.
It seems to me the most direct solution to noise in long runs of interconnects is balanced cables and XLR connectors. However, there is, it seems, only one right way to do this but mant wrong ways. Suggest taking a look at an article on this subject at www.rane.com. I think the topic is gounding.
Use Balanced Sending & Receiving ICs
If you do not have balanced output/input devices,
you can use these high quality ICs
dedicated for this purpose.
SSM2142, converts unbalanced to balanced, drives the line, XLR
SSM2141, converts balanced to unbalanced, receives the line, XLR
Have very low Total Harmonic Distortion, THD
You can find datasheets, schematics on Web
If you do not have balanced output/input devices,
you can use these high quality ICs
dedicated for this purpose.
SSM2142, converts unbalanced to balanced, drives the line, XLR
SSM2141, converts balanced to unbalanced, receives the line, XLR
Have very low Total Harmonic Distortion, THD
You can find datasheets, schematics on Web
I'm glad I came across this topic. I had a friend who wanted to change the connector on her Kenwood turntable from RCA (plus separate ground fork) to XLR. I wasn't able to help her but I told her that if I ever found out how to do it I would let her know. She just used an XLR to RCA adapter but she would have liked to put the connector on the raw wires. Assuming this was possible, how would you pin it out?
RCA pin->
RCA gnd->
wire gnd->
Any help would be appreciated
RCA pin->
RCA gnd->
wire gnd->
Any help would be appreciated
Re: So her Amp have RCA input?
In your situation for surrounds i'd run long speaker wire.
On the other topics that have come up:
I run about 4m of single ended cable from my pre-amp to my active crossovers with no problems. When my new pre-amp arrives and i get it built, and when i get my new XO designed and built i will be switching to balanced. I'd also like to wire my turntable with balanced/differential output to get the max out of the new pre.
Why does the lady with the TT want XLRs? Does she want to run it differential (ie two connectors) or does she just want a single plug?
dave
In your situation for surrounds i'd run long speaker wire.
On the other topics that have come up:
I run about 4m of single ended cable from my pre-amp to my active crossovers with no problems. When my new pre-amp arrives and i get it built, and when i get my new XO designed and built i will be switching to balanced. I'd also like to wire my turntable with balanced/differential output to get the max out of the new pre.
Why does the lady with the TT want XLRs? Does she want to run it differential (ie two connectors) or does she just want a single plug?
dave
nania said:
A pair of XLR inputs for balanced. The pre-amp manual should have the pin-out or contact the manufacturer or pop the top.
If the arm is wired with a common ground -- The cart hot goes to the non-inverted input, ground to ground and the inverted input is left floating.
If there are seperate grounds you can take them (separatly) to the inverted input and leave the ground unconnected.
dave
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