Interconnects - capacitance and other considerations

All general audio posts go here.
Forum rules
1. No ad-hominem
2. No spamming or shilling
Berty bass
Posts: 44
Joined: Tue Nov 21, 2017 9:54 pm
Great Britain

Interconnects - capacitance and other considerations

Unread post by Berty bass » Tue Jan 09, 2018 9:59 am

I've been giving some thought to interconnects recently due to the need to extend a captive interconnect on my turntable. Googling quickly led me to ascertain that there were very few off the shelf interconnect extension options out there and custom ones could be quite expensive. Further 'homework' seemed to establish that one of the most important considerations was low capacitance. Mark Grant offers an interconnect which he makes up with low capacitance Van damme instrument cable at a very reasonable price. This led me to a bespoke instrument cable maker who frequents one of the bass players forums I subscribe to, who took on the challenge of making up the interconnect cables I required and recommended an even lower capacitance cable - Sommer LLX. The Van damme cable is <90 pF/m and the cable my guy is using is <52 pF/m. The question therefore is this - what do we consider LOW capacitance and what other considerations make the esoteric £00's+ cables 'better' than my <52 pF/m bespoke cables? What am I missing in other words?

Daniel Quinn
Posts: 7077
Joined: Thu Jul 12, 2012 7:16 am
Nicaragua

Re: Interconnects - capacitance and other considerations

Unread post by Daniel Quinn » Tue Jan 09, 2018 10:36 am

We don't, we buy nva, perhaps it's a question for other fora ;)
Even a stroke didn't result in me liking AOS

Berty bass
Posts: 44
Joined: Tue Nov 21, 2017 9:54 pm
Great Britain

Re: Interconnects - capacitance and other considerations

Unread post by Berty bass » Tue Jan 09, 2018 11:24 am

Daniel Quinn wrote:
Tue Jan 09, 2018 10:36 am
We don't, we buy nva, perhaps it's a question for other fora ;)
And there was me thinking this might be an appropriate question for the 'General Audio' forum on this site! Dear God, you;re not going to make me post in PFM are you? :grin: :)

User avatar
Dr Bunsen Honeydew
Posts: 27915
Joined: Wed Jul 11, 2012 7:26 pm
Location: Muppet Labs
Great Britain

Re: Interconnects - capacitance and other considerations

Unread post by Dr Bunsen Honeydew » Tue Jan 09, 2018 11:29 am

I think what DQ means is specifications are only a small part of the story, your music and your ears are the important bit.

In my case the need for low cap cables led me to listen to loads of them starting over 30 years ago. I think I have probably listened to all types now, especially all the RG (military spec) ones. Result - specs just point you in the right direction to start your work, subjective choice and how to use them are far more important.

Simon Hickie
Posts: 511
Joined: Mon Feb 27, 2017 1:47 pm
Location: East Staffordshire
Great Britain

Re: Interconnects - capacitance and other considerations

Unread post by Simon Hickie » Tue Jan 09, 2018 12:00 pm

Cables = minefield. It's not all about capacitance, although that is important. Shielding, solid core vs. stranded, inductance, geometry all play a part. The cable market is awash with overpriced items with over-hyped marketing speak.
“The reasonable man adapts himself to the world: the unreasonable one persists in trying to adapt the world to himself. Therefore all progress depends on the unreasonable man.” George Bernard Shaw.

Berty bass
Posts: 44
Joined: Tue Nov 21, 2017 9:54 pm
Great Britain

Re: Interconnects - capacitance and other considerations

Unread post by Berty bass » Tue Jan 09, 2018 3:04 pm

Dr Bunsen Honeydew wrote:
Tue Jan 09, 2018 11:29 am
In my case the need for low cap cables led me to listen to loads of them starting over 30 years ago. I think I have probably listened to all types now, especially all the RG (military spec) ones. Result - specs just point you in the right direction to start your work, subjective choice and how to use them are far more important.
Doc, in terms of capacitance - appreciating this is only a small part of the picture (well, sound) - is 52pF/m or less 'low'? I've no reference point at all. It's obviously lower than the Van damme cable I mentioned but is it low when compared to other cables also?

User avatar
Dr Bunsen Honeydew
Posts: 27915
Joined: Wed Jul 11, 2012 7:26 pm
Location: Muppet Labs
Great Britain

Re: Interconnects - capacitance and other considerations

Unread post by Dr Bunsen Honeydew » Tue Jan 09, 2018 3:17 pm

It is lower, smaller figure is lower.

Simon Hickie
Posts: 511
Joined: Mon Feb 27, 2017 1:47 pm
Location: East Staffordshire
Great Britain

Re: Interconnects - capacitance and other considerations

Unread post by Simon Hickie » Tue Jan 09, 2018 6:22 pm

According to some sources: 100pF/m = quite high; 70pF/m = middling, 40pF/m = very low.
“The reasonable man adapts himself to the world: the unreasonable one persists in trying to adapt the world to himself. Therefore all progress depends on the unreasonable man.” George Bernard Shaw.

_D_S_J_R_
Posts: 3821
Joined: Mon Feb 03, 2014 9:53 am
Location: The end of the road in Suffolk Coastal.
Wales

Re: Interconnects - capacitance and other considerations

Unread post by _D_S_J_R_ » Tue Jan 09, 2018 6:27 pm

In my experience it only seems to matter in extremis - i.e. very long interconnects with a passive preamp or one or two very fussy older design mm type pickups. With cables of around 1 to 2 metres, a 100pF/m cable is just fine I believe, so please don't worry about it...
...I have renounced the worldly bustle and live in peace at a quiet place,
I live alone in this my heaven, in my love (and) in my songs.

Simon Hickie
Posts: 511
Joined: Mon Feb 27, 2017 1:47 pm
Location: East Staffordshire
Great Britain

Re: Interconnects - capacitance and other considerations

Unread post by Simon Hickie » Tue Jan 09, 2018 6:30 pm

FWIW, Graham Slee suggests you need a total of 100pF between cartridge and phono input. As a guide he also suggests you assume 25pF for the arm's internal wiring, needing you to find 75pF worth of capacitance - either shorter length of higher cap cable or longer length of lower cap cable. If you are talking about cable extensions, you need to know the capacitance of your existing cartridge to plug setup. That is of course if what I've said is not a load of :Bllocks:
“The reasonable man adapts himself to the world: the unreasonable one persists in trying to adapt the world to himself. Therefore all progress depends on the unreasonable man.” George Bernard Shaw.

Post Reply