would 50 feet speaker wires be harmful to amp?


I am considering using my amps to drive my second set up on another floor of my house. Both my primary and second set up requires bi-amps and for now I would like to hold off investing in another amp.

I was thinking of just running 50' speaker wires to my second set up to drive my celestion sl6000 speakers there. My amps are Ampzilla 2000 MK2 and Mccormick DNA500.

Since I'll only be listening to one set up at a time anyway, I would just connect for the room I'll be listening in. I play my music off my computer server mostly these days and that is network driven to my PS PWD DAC which I can control from any room in the house.

My concern is with such lengths of speaker wire, would the inductance/capacitance add up to a level that could be harmful to my amps. Given the lengths of speaker wire, I'm incline to go with basic speaker wires to manage cost in that area as well.

I also have a pair of VTL MB450 which I may switch in as well. If SS amps can handle such lengths of speaker wire, would tube amps be the same?

Thoughts on this anyone?

Gerald
geraldedison

Showing 1 response by almarg

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