would 50 feet speaker wires be harmful to amp?

Good question. Excessive total capacitance can cause some amplifiers to oscillate, resulting in damage, especially if they have particularly wide bandwidth and use lots of feedback.

I have no familiarity with the design of your particular amplifiers, but my guess is that you'll be ok with 50 feet of the Blue Jeans/Belden 5T00UP cable, detailed specs shown here. Total capacitance for the 50 foot run would be 1300 pf, which is in the same ballpark as 1 foot(!) of some of the ultra-high capacitance cables that have been known to blow up some amplifiers when used in typical lengths.

Although I do have a bit of concern due to this statement in Stereophile's review of the Celestion System 6000:

The only warning concerns the SL600 load impedance at near ultrasonic frequencies, where it becomes predominantly capacitative at around 4.5 ohms. One or two amplifiers with a poor stability margin might be uncomfortable with it.

So the amplifier driving the high frequency part of the speaker would be subjected to both the capacitive loading of the speaker and the relatively high cable capacitance.

Resistance and inductance are only concerns with respect to sonics, not damage, and the numbers for 50 feet of this particular cable look reasonable in relation to the Celestion's impedance.

For a more specifically knowledgeable answer, try contacting Steve McCormack about the DNA500 (A'gon member "stevemcx" or via SMcAudio.com), and the Ampzilla people via the contact information shown at their website. Likewise with respect to the VTL, for which my guess is that you'll also be ok, but the maximum tolerable capacitance may depend on which of its four different feedback settings is used.

Regards,
-- Al

50Ft very bad 20Ft should be max Dude!!

Ebm does not know what he is blathering on about. Just be sure to use nice large gauge OFC copper cabling and you'll be in good shape. For a 50 ft. run I would use 10 or 12 gauge (awg), 10 awg is larger than 12 awg.

Also, if this is to be an in-wall run, be sure to use the proper conduit to eliminate the possibility of introducing any fire hazard.

-RW-

My amplifier and speakers are on opposite sides of my room with the speaker wire running down one wall, through the cellar, and up the other wall. I am not exactly sure of the total length, but it is at least 30 feet and probably longer. The Yamamoto A-08a 45 SET seemed to struggle, but my current Ancient Audio 300b SET has no problem with the length.

The impedance swings of your speaker is much more challenging to your amplifier than any additional loss that a cable may add.

I wouldn't worry about it,

Al,

Thanks for the detailed and thoughtful response. I especially appreciate the note from Stereophile on the Celestion speakers.

Thanks to the other folks on their comments and sharing as well.

I will be careful with speaker wire selection and will focus on low gauge wires for the task.

Gerald

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I've had 50ft runs with no problems for years. Use 10 or 12 gauge and you'll be fine.
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Pssst, (8awg.) SHHHHHH

I think you will find that in running cable lengths that long that you will loose a lot of definition!

Things like vocals will be harder to discern; details will be smeared and lost.

There is more to speaker cable than just resistance and capacitance numbers. Cables also have something called Characteristic Impedance (normally thought to only be a phenomena of RF transmission lines). No speaker can perfectly match the CI of a particular cable; this results in a loss of definition due to time delay issues (smearing). Normally in short cables this is not a big problem but does account for some of the differences we hear in cables, but when you run a speaker cable that long these effects are magnified.

If you are just looking for background music it will work fine.

Glad to see others have done this without issues.

I recognized this is sub-optimal for music playback but my second setup is really for background music and not critical listening.

My primary setup is in a dedicated music room with proper sound treatment, but I would like to have some decent music even when I'm working around the house :)

Gerald