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Advice on a long audio cable run

bobins08

bobins08

Celebrating Life
I am looking at a situation where the distance between my pre-amp output and power amp input requires a 35 foot cable run.

Looking for a solution that provides good quality cables and does not break the bank. I am not someone that can "hear" state of the art cables but I sure do not want the cables to degrade the sound either.

I see Mono Price has RCA component cable that you can get in customs length for a very low price. I do not want low quality with the low price. Anyone know about this cable?

I also see Blue Jeans Cables and the price is significantly more, 35 feet cost $117 for their best pre-made cable (LC-1). This is in my budget and I like their cables. I use them for connecting other components and I know I am getting a good product.

Any other options on pre-made?

I am also open to DIY. What cables and connectors represent good value for DIY?

Thanks in advance,

Bob
 
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I use a 25' DH Labs BL-1 RCA cable from my preamp to my electronic crossover and power amps. It has been in place for 15+ years. IME many Monoprice cables have excessively tight RCA connectors.
 
JoeESP9 said:
I use a 25' DH Labs BL-1 RCA cable from my preamp to my electronic crossover and power amps. It has been in place for 15+ years. IME many Monoprice cables have excessively tight RCA connectors.
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Looks like nice cable. Quite a bit more cost than Blue Jeans.

thanks!
 
I bought it 15+ years ago.:D It was substantially less expensive for me then, as I was still working.
 
Canare is a commercial cable company that makes cables for professional musicians and sound reinforcement systems that might have something more to your liking and budget. Monster cable is another choice and is not to far out of sight.
 
twiiii said:
Canare is a commercial cable company that makes cables for professional musicians and sound reinforcement systems that might have something more to your liking and budget. Monster cable is another choice and is not to far out of sight.
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Thanks, I'll look into that

Whatever I get needs good shielding and low capacitance.
 
darkblue94 said:
Then you have your answer already, the Blue Jeans Cable LC-1, I use a 20' run from preamp to amplifier to keep the speaker cables short (6').:thumbsup:
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Yes, the only thing I want in between my speakers will be my power amp, on a low stand. I want to use short speaker cable and keep the sound stage uncluttered. The preamp, other electronics, and source (turntables, CDP) will be away. That's why I need 35 ft of good cable. Either I buy the LC-1, a known commodity, or make my own.
 
Monoprice cable is inexpensive, but not cheap. I have purchased a large amount of my interconnects from them. Good stuff. Only issue is they are a West coast company, and I am on the East Coast. Shipping usually takes a week.
 
Been there.....done that. Cable brands are not the main topic for long runs, rather, it is the cable capacitance and whether the preamp's outputs are low enough impedance to swamp out the capacitive load. You have 2 options:

1) Confirm that your preamp, not named, is suitable for such a run and the cable capacitance per foot is suitable for that preamp.

2) Covert the audio signal to a balanced system, use balanced cables and then convert it back at the other end. You can use something like this for the active devices and then use some balanced cables with XLR connectors.

Cheers,

David
 
dshoaf said:
Been there.....done that. Cable brands are not the main topic for long runs, rather, it is the cable capacitance and whether the preamp's outputs are low enough impedance to swamp out the capacitive load. You have 2 options:

1) Confirm that your preamp, not named, is suitable for such a run and the cable capacitance per foot is suitable for that preamp.

2) Covert the audio signal to a balanced system, use balanced cables and then convert it back at the other end. You can use something like this for the active devices and then use some balanced cables with XLR connectors.

Cheers,

David
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Uh oh. New information.

I have a Musical Design Pas Pro preamp. Mine is somewhat a one of a kind. It's in a Hafler 101 case but the only thing I use from hafler are the input selector switches. It is a tube preamp board, a TKD volume pot, an external power supply, all new rca input and outputs. I run NOS Amperex 7308 tubes in it and I love it.

I'll call John today, get the output specs, and see what he recommends.

From what I can tell, since my power amp has unbalanced inputs, I need a converter box on each end. Plus the balanced cable.

Hmmmm. Thanks for the information. I'll tell you what John had to say about it.
 
I've bought many Hafler driver boards and upgrades from John at Musical Concepts. He's a good guy who knows what he's designing. It is a nice preamp you have. Good idea to consult with him.

Cheers,

David
 
@dshoaf, @Pio1980

I talked to John at Musical Concepts, the designer of my preamp. He said the preamp output impedance is not “super low” as it would need to be for 40 feet of cable. Using 40 feet of low capacitance (13 pf/ft) cable provides 520 pf. He said there could be some roll off, maybe not under 20K so maybe not noticeable. He also thinks there could be 1-2 dB of attenuation to the signal. He was not keen on it.

Reduce the length to 20 feet (260 pf) and he thinks the problem is gone.

He recommended doing a mod to one of the two preamp outputs provided. Make one a low impedance output by adding a MOSFET buffer circuit. He did not originally do this because this is a tube preamp, but he has thought about it.

He was not excited about the use of converter boxes for balanced outputs. I think we could do this mod for less money than the boxes.

So, I am going to think this over. Going to look at the room and re-measure. The cable length are long because I want to run the cables cleanly along the baseboards, out of sight and out of the way of foot traffic. Speakers and amp along the back wall, other equipment along the side wall.

I am not in a big hurry so I can think this through for awhile.
 
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There's another thread on type, gauge, and length of speaker cabling, so there's no ideal solution aside from gear designed for long balanced lines. So, where and how to make the most favorable compromise?
In your situation, it will probably be the lowest capacitance line level unbalanced lines do-able.
 
I just re-measured my room. I can do this layout with 28 feet of cable. At 13 pf/ft that is 364 pf.

I have some time to think about it.
 
bobins08 said:
I just re-measured my room. I can do this layout with 28 feet of cable. At 13 pf/ft that is 364 pf.

I have some time to think about it.
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I wouldn't put too much time into thinking about it.

Not sure what the preamp dude meant by "not super low" so let me throw out a number I'd consider pretty high for pre out impedance....

With 2,000 ohms output impedance, ~36pF/meter, 10 meters long, the -3dB point is 221kHz.

In the absence of a specified pre output impedance I suggest the above is conservative (meaning the F3 point is probably even higher than 221kHz).

So, IMO, what you want to do will not be problem using the BJC LC-1, nor the Belden 1505F if you want something a little smaller diameter and a little more flexible.
 
I agree that just "tossing in" a pair of converter boxes isn't a great solution. I've gone through some and as far as audio quality, they tend to be lacking. If you have a decent system, then you're lowing the result to the quality of the inclusion of two of them.

Equipment designers look long at hard at each and every equipment stage and stress much on eliminating any they can, as each stage adds more in the path via each stages current loop. So then to go and drop in a couple unrelated (separate PS's) boxes made for an econo price point, just isn't a great thing to do...unless absolutely necessary.

The good thing about driving the capacitive load in trial and seeing if the HF rolloff is noticeable is that it's not harmful. It's just HF rolloff. But driving that capacitive load does also up overall distortion numbers some too, so it does have another dimension there too.

EV3
 
Update --- I was able to position the equipment such that 27 feet of cable will do the job.

I bought Blue Jeans LC-1, very low capacitance and well shielded.

I connected the 27 feet of cable in place of my current 3 foot LC-1 cable. Good news is I hear no difference in the sound, no HF roll off, no difference in the volume pot position. With that, I moved my amp in between my speakers, setting it on a sturdy low stand. Now I can connect shorter runs of better speaker cable to my s speakers.

With my new arrangement I connected Acoustic Zen Satori speaker cable to my Acoustic Zen Adagio speakers. These cables give me superior sound to the original configuration which required long runs of generic copper speaker cable.

Mission Accomplished! The Adagios sound even better now.

Cheers, Bob
 
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