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tube amps/low capacitance cables?

The owner's manual for my 35w p/p tube amp recommends low capacitance speaker cables - but, it doesn't say why. On my two way monitors, I've been using TG Audio HSR silver cables which had been delivering authoritative bass in my former SS amp set-up. But, with the tube amp, the bass is now very weak. So, I'm assuming that these HSR cables are high capacitance, low inductance. I swapped in a pair of Speltz non-twisted anti-cables(low capacitance) and the bass returned. Since assuming can be a dangerous thing, can anyone elaborate about low capacitance cables working better (or not) with tube amps?
steakster
eldartford
4,262 posts
 
That's strange. I would expect high capacitance cables to affect high frequency, not low. A tube amp, with relatively high output impedance at high frequency would be affected more than a low impedance ss amp.

Ask the amp manufacturer.
gregm
3,411 posts
 
Strange indeed -- unless the older cables were higher gauge (i.e. thinner) than the new ones -- and generally too thin for the new application?
gs5556
1,242 posts
 
It's not so strange. Tube amps have relatively low output current and low damping factors which make it more difficult to control woofers at low frequencies. The impedance of the speakers plus the cables affect the damping factor. If high capacitance cables are used, the impedance is higher at low frequencies, increasing the output impedance the speaker "sees" which makes things worse for low end performance.
shadorne's avatar
shadorne
7,477 posts
 
I don't think there is a rule of thumb. In general, if the speaker cables have a major impact on the sound then I would be more concerned about the amplifier design, how the speaker load varies with frequency and the way the two match...just my two cents.
atmasphere's avatar
atmasphere
12,099 posts
 
Whatever the deal is causing the lack of bass with that cable, its not capacitance. Length, cross sectional area and the characteristic impedance are more likely variables.

By decreasing the 'damping factor' the bass would actually increase, although there may be less definition.
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