Mark Grant VDC speaker cables

[Haselsh1]

Just bought a 2m stereo pair of Mark Grant VDC loudspeaker cables from Shane here on AOS and got them today. Couldn't bloody wait to try them out so connected up and switched on. CD was Shpongle, Museum of Consciousness, and the inital 30 seconds or so was pretty good but then the sound just completely broke up into distortion. Switched off, put my original NVA LS5's back on and everything is brill again. Now I know from experience that some amplifiers and cables just do not mix so this may be one of those cases. This is in no way reflective of Shane. He sold me these cables and I willingly bought them. Shame they are not compatible.

[Pieoftheday]

Just bought a 2m stereo pair of Mark Grant VDC loudspeaker cables from Shane here on AOS and got them today. Couldn't bloody wait to try them out so connected up and switched on. CD was Shpongle, Museum of Consciousness, and the inital 30 seconds or so was pretty good but then the sound just completely broke up into distortion. Switched off, put my original NVA LS5's back on and everything is brill again. Now I know from experience that some amplifiers and cables just do not mix so this may be one of those cases. This is in no way reflective of Shane. He sold me these cables and I willingly bought them. Shame they are not compatible.

I'm certainly no expert here but I can't see myself why such distortion means incompatible? Perhaps the cables are faulty in some way? Due to handling in postage?

[YNWaN]

As above; some amps (Naim, NVA, Spectral etc.) are not compatible with some cables but even if used they don't cause the reaction described.

[Arkless Electronics]

As above; some amps (Naim, NVA, Spectral etc.) are not compatible with some cables but even if used they don't cause the reaction described.

Worst case I would expect the destruction of both the amp and speakers actually.... I have seen this happen with an NVA amp about 20 odd years ago.

[Marco]

I have seen this happen with an NVA amp about 20 odd years ago.

Ah that's interesting... It's a pity there won't be any of it there at MiBO, because as the show is on the 5th Nov, we could commemorate bonfire night!

Marco.

[Mark Grant]

Now I know from experience that some amplifiers and cables just do not mix so this may be one of those cases.

Never good to hear of any problems but if you look at the specifications you have speakers are not really compatible with the high power amplifier.
The amplifier specifies a minimum speaker impedance of 4 ohms and will output 300 watts per speaker at 4 ohms.
The Kef Q500 have a nominal impedance of 8 Ohms with minimum impedance of 3.2 ohms claimed.
see screen grab from Amazon:



back of amplifier that mentions 4 ohms:


Link to a webpage that measured the R700 ( similar 8 ohms nominal speaker) at 3.3 ohms with 10 feet/3.3 metres of cable:
http://www.stereophile.com/content/k...F5u2m1Hhub2.97

The 2 metre lengths of 4 mm2 van damme has a resistance of about 4.7 ohms per km that is about 0.005 ohms per metre + crimped banana connectors which don't add much resistance.

So I guess your previous cable and connectors had enough extra resistance and different inductance and capacitance measurements to work OK with the 4 ohms minimum of your amplifier where as a thicker and lower resistance cable doesn't add enough extra resistance onto to 3.2 ohms speakers. Most people want low resistance cable but in the case you need slightly higher resistance to add on to the 3.2 ohms to get it near the 4 ohms.

Hope that helps.

[Haselsh1]

OK there is a further development to all of this.

Fired up the system tonight with the new valve preamp and the sound out of the right speaker crackled and cut out. OK, it cannot be the Grant cables after all. I swapped over the KEF's and fired up again expecting the crackles to change sides. Yeah...? The problem appears to have gone completely.

It is unlikely to be a dodgy speaker connection as I have now tried two different sets of cables so all that leaves is an interconnect but all I have done is swap over the KEF's.

Confused...? You bet...!

[Yomanze]

Worst case I would expect the destruction of both the amp and speakers actually.... I have seen this happen with an NVA amp about 20 odd years ago.

There was a few years ago when Townsend Isolda was popular, until it blew certain amps up. :P

Read the manual hey!

[Haselsh1]

OK, tried the system out again tonight and the crackling and cut out occurred exactly as in the first instance so it is definitely not the KEF's. Decided to remove the Bushmaster from circuit and the crackle and cutout disappeared again. I think it is the Bushmaster that is faulty so at the moment I am using it on coax no3 and not coax no4 as was the case. However, the sound of the Bushmaster when it is working correctly is lots better than the Marantz I am using as a transport. I still hope to get around to reviewing the Mark Grant VDC cables at some point

[Haselsh1]

Comparison: NVA LS5 1.5m stereo pair against Mark Grant VDC 2.0m stereo pair

Music choice: Zero 7, Simple Things

The very first thing to really strike home here is the extra treble brightness of the VDC cables. The next thing is the much more forward upper midrange. This in turn leads to the third thing, a much more prominent level of detail in the mid and upper mid. Nothing about the bass struck home like these other notable differences did. On further listening it became very apparent that the treble and upper mid was much more clear and better defined with a nice crystallinity to it that made it very impressive. I think that these cables will really suit EDM dance music.

So, back to the NVA LS5 cables. Much more delicate treble and much more natural midband. Rather hollow and more reticent bass though. Far more relaxed vocals but not as precise stereo focus. Kind of like comparing valves with trannies.

Which do I prefer...? I don't know in all honesty. I think that the NVA cables are the best all rounders but I think that the VDC cables would so love electronic music.

Next step...? A session this weekend with Deadmau5.