Cables questions for AKSA gear

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Jens

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Cables questions for AKSA gear
« Reply #20 on: 24 Aug 2005, 08:05 am »
When making your own speaker cables, there is one caveat with the AKSA amps: they don't like too high capacity. I don't remember the exact figures, though ...

Hugh, could you kick that in here?

AKSA

Cables questions for AKSA gear
« Reply #21 on: 24 Aug 2005, 11:37 pm »
Hi Jens,

Yes, good point, best to keep it below about 5000pF, or 5nF.

Most speaker cable of the conjoined variety (cf. figure eight profile) is around 500pF per foot, so at 10', you are pushing the limits.

Longer cable will be fine for the amp, but it won't sound as good.  Low capacitance is the way to go.  By keeping the leads separated by an inch or so, you can get capacitance down to perhaps 40-50pF per foot or less.  While the inductance will increase in this configuration, it's still not an issue as the inductance in the driver voice coils is considerable anyway, typically around 3mH.

A very important consideration in the speaker lead choice is DC resistance.  It's really significant as it affects damping factor very strongly.  Anything over about half an ohm is notionally audible.  Thankfully most are no more than 0.2R at the most, so this is seldom an issue.

Cheers,

Hugh

stvnharr

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Cables questions for AKSA gear
« Reply #22 on: 25 Aug 2005, 05:07 am »
Curious and interesting to read all the words about the dreaded capacitance issue in cables.  All well and good, BUT...
I know of only one company that issues capacitance ratings for their cables, and that's some small outfit over in Adelaide.  Perhaps some others have actually listed capacitance, inductance, resistance ratings for their cables, and I just missed it.
My experience is that most all cable makers market their cables based mostly on cable geometry, and of course their own particular cable geometry is the best!

As for capacitance, is there some kind of capacitance meter in which to measure one's cables?????
AND, what is the ultimate effect of the capacitance issue?  I may have missed a thing or two, but I've never heard speaker cables described other than warm, neutral, or bright.

ALSO, what is the ultimate capacitance disaster?  I've heard of a number of audio blunders, but I have never heard of an amp blowing up because the "wrong" speaker cable got connected!

I heard a rule of thumb about cables a long time ago, and it's essentially "keep all cables as short as possible".   I think this makes darn good sense and should limit any effects of these things that essentially cannot be measured.

Oh, and there's also the cable inside the amp connecting the output spade to the binding post, and there's the cable inside the speaker box, which can amount to several feet if the speakers are big or floorstanders.  It's all part of the same signal transfer path.

Tinker

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Cables questions for AKSA gear
« Reply #23 on: 25 Aug 2005, 07:24 am »
Quote from: stvnharr

ALSO, what is the ultimate capacitance disaster? I've heard of a number of audio blunders, but I have never heard of an amp blowing up because the "wrong" speaker cable got connected!


I've managed to do it. I once lowered the gain on an amp, resulting in lower stablity margin. A 3m ribbon cable with a 2nF per metre caused an oscillation which destroyed the output stage before I could switch it off.

T.

andyr

Cables questions for AKSA gear
« Reply #24 on: 25 Aug 2005, 09:22 am »
Yes, Steve,

I've also blown up an amp (pre-AKSA days) and the only reason this could've been was because it couldn't cope with the 15m run of Naim speaker cable (which the Naim amp could!).  As soon as I switched on, the output transistors failed!  I had it repaired and tried again ... same thing happened!  An expensive learning exercise!

Regards,

Andy

Jens

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Cables questions for AKSA gear
« Reply #25 on: 25 Aug 2005, 10:30 am »
Quote from: AKSA
Hi Jens,

Yes, good point, best to keep it below about 5000pF, or 5nF.

Most speaker cable of the conjoined variety (cf. figure eight profile) is around 500pF per foot, so at 10', you are pushing the limits.

Longer cable will be fine for the amp, but it won't sound as good.  Low capacitance is the way to go.  By keeping the leads separated by an inch or so, you can get capacitance down to perhaps 40-50pF per foot or less.  While the inductance will increase in this configuration, it's still not an is ...


This also means that cables with braided or helix-type configuration may be OK, but my advice would be to check or have the specs for the cable checked before buying.

One example of a very good braided cable is the Kimber 8TC, which has a capacitance of around 820 pF for a 2.5 metre length - no problem there. And Kimber actually does not keep the specs a secret - I have them from the Scandinavian distributors homepage. Inductance for the 8TC is around 0.35 uH, and resistance as low as around 0.05 ohms.

AKSA

Cables questions for AKSA gear
« Reply #26 on: 25 Aug 2005, 11:01 am »
Jens,

These are very good figures.  There's 1.4uH in series with the hot speaker lead anyway, in the form of the output inductor.  This is before the inductance of the voice coil is considered, too.

Cheers,

Hugh

MattCassidy

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Cables questions for AKSA gear
« Reply #27 on: 25 Aug 2005, 11:13 am »
I love it when I start a topic and then cannot understand most of what is said after the first five minutes.javascript:emoticon(':?'). Sigh. I need to get some longer cables soon and they may run to 3.5 metres each.

I currently use Flatline gold quoted at 8.6pF/ft. sounds pretty low to me, Will I have to be careful if I buy these longer runs? Or should I continue along with my current "Ignorance is bliss" stance?

Matt

andyr

Cables questions for AKSA gear
« Reply #28 on: 25 Aug 2005, 11:21 am »
Just as a matter of interest for y'all, I compared/measured the specs for the following spkr cables:
* Nordost SPM Ref
* Naim cable
* Cat5, using 1 jacket (8 wires) for '+' and one for '-'.  The two jackets were side-by-side in a conduit (over a 15m run).

The following are all per metre:

Nordost SPM Ref:
L: 0.21uH  C: 18pF  R: ??

Naim cable:
L: 1.4uH  C: 16pF  R: 9mO

Cat5:
L: 0.9uH  C: 13pF  R: 11mO

So a pair of Cat5 jackets is a great low-C cable to use for long runs!  No stress at all for 18m runs with an AKSA 55.  (And it's to the study so "music" is what I want there, not "hi-fi"!!)

Regards,

Andy

AKSA

Cables questions for AKSA gear
« Reply #29 on: 25 Aug 2005, 11:25 am »
Hi Matt,

Nah, 8.6pF per metre is fine and dandy.

You could quite happily use 15 metre runs of this cable with your AKSA.......

Andy,

Interesting about the CAT5, huh?  You could use 25 wire ribbon (if you can get it??), keep the middle three conductors unused to separate the runs, and use the left 11 for hot, and the right 11 for cold!  AND you could park it under the carpet!!

Cheers,

Hugh

obiwan

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Cables questions for AKSA gear
« Reply #30 on: 25 Aug 2005, 11:32 am »
Hi Matt,

Do you still have the baby Quads and did you get yourself a sub afterall?

MattCassidy

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Cables questions for AKSA gear
« Reply #31 on: 25 Aug 2005, 11:42 am »
Hi Obiwan,

I still have the Quad 11L's. But am trying to get my hands on some B&W 805s's or 804s. I got a sub and tested it but wasn't convinced and took it back. Went on a listening tour around a few places the other day, Heard some Aurum Cantus Melody's with a ribbon tweeter, quite nice. Then some Ambience 1600's, unbelievable sound stage and detail but a bit woofly on the base. Then went and had a listen to a pair of B&W 704s's (new series), I liked these too and had tracked down a set on ebay new. I would have bought them if I hadn't have listened to the 805s's next. What can I say, they were lovely just sounded soooo right!
So now I want a pair of speakers that are only about double my budget!

How are you going, did you make an AKSA or still got the Bel CAnto, and the Dynaudio's, I was thinking when I finish the GK-1 (soon) of having another Brisvegas Aksa Spectacular at some stage, so keep an eye out.

Matt

obiwan

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Cables questions for AKSA gear
« Reply #32 on: 25 Aug 2005, 12:12 pm »
I've been on quite an adventure Matt.

First I ended up getting a Velodyne DD15 sub to compliment the Dyn Special 25's that I took to your place. Then I decided to start building up surround sound again and ended up getting 2 pairs of the little Dyn Contour SR's. Well of course I had to try the SR's with the sub to check out their 2 channel performance and other than lacking the dynamics of the S25's, in every other way I like the little SR's more (at almost 1/3 the price). They just disappeared, they were more laid back, smoother, sounded great on almost all recordings whereas the S25's always had to have great recordings.

I ended up getting new stands from Canada for the S25's which makes them look a milion dollars, but 3 or 4 weeks ago I did something rather rash and bought a pair of the large Contour S5.4's second hand from New York. Yes they're f***ing huge but they sound great and image as well as the little SR's, in fact even better. Even though the tweeter is low with its inverted geometry, I'm getting pretty good vertical spacial cues with cymbols etc coming from 3 feet above the tweeter, quite amazing.

So now my bloody Velodyne DD15 is a bit redundant, except for movies.

I've wasted way too much money on this hobby. It ends now!!!

jinca

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Cables questions for AKSA gear
« Reply #33 on: 26 Aug 2005, 01:36 am »
I bought a set of 10ft GOERTZ M1  (500pf/ ft) before I built my AKSA.
I guess I am pushing Hugh's Capacitance limit  (< 5000pf).

To prevent possible oscillations, the GOERTZ M1 comes standard with this RC load at the speaker terminal  (.1uF series 10R).  Not sure what this really means to my sound.

There is much conflicting information out there, and I am sticking with what I have until I feel I should change it.

Since GOERTZ markets low Impedence (match with speakers), I am curious what you think about this.

http://www.alphacore.com/mifaq.html

rabbitz

Cables questions for AKSA gear
« Reply #34 on: 26 Aug 2005, 01:41 am »
Quote from: obiwan

I've wasted way too much money on this hobby. It ends now!!!


HA.... I've heard and said that before  :wink:

stvnharr

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Cables questions for AKSA gear
« Reply #35 on: 26 Aug 2005, 03:12 am »
Hm,
I was thinking of speaker wires as being on the order of 6 ft, 2 meters to many, rather than 15 meters, or 50 ft to some.

Interesting to hear tales of amp failures due to wrong cable hook up.

Still, keep 'em short, don't worry, just listen.

andyr

Cables questions for AKSA gear
« Reply #36 on: 26 Aug 2005, 11:07 am »
Quote from: stvnharr
Hm,
I was thinking of speaker wires as being on the order of 6 ft, 2 meters to many, rather than 15 meters, or 50 ft to some.

Interesting to hear tales of amp failures due to wrong cable hook up.

Still, keep 'em short, don't worry, just listen.
Hi Steven,

I suggest 6' or less is kinda "optimal" ... you need all your equipment in the right place to get this short (and still listen in stereo!!).

In my "main" system which involves active 3-way crossovers, I have 3 AKSA monoblocks directly behind each Maggie panel ... each of the 3 (pairs of) cables is just over 4' long.

This is my "critical listening" system so spkr cable length is important.

In my other system (the 50' one, also driven by an AKSA), as well as my main speakers - 12' bi-wired cables - I am driving speakers in bedroom and study (either/or/neither, set by a pair of DPDT switches) ... these speakers are obviously a lot further away and are not "critical" listening.  The only important factor is that they must be low enough C - in spite of their excessive length - not to upset my AKSA.

Regards,

Andy

stvnharr

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Cables questions for AKSA gear
« Reply #37 on: 26 Aug 2005, 03:49 pm »
Andy,
I pretty much figured that the 50 footers were for a remote speaker setting where getting some sound was the main criteria.  I'm sure you'd agree that it's something of a compromise.

Optimal is a bit tricky, but in a 2 channel setup, used to just be called stereo, it's reasonably easy to have short cables.  In fact, when my amps were in mono cases,  I could have 1 meter IC's to amps, and 1 meter cables to speakers.

And as for cost, I've gravitated from Cardas Hex Golden, about $1k at half price dealer demo cost to my braided wire for less than $100.  The Cardas were on the warm side of sound.  The braided are very neutral and are big enough in awg to have all the bass.

In my experiences, I've found the biggest differences in speaker cables to be bass transmission, and, though some may differ in opinion, bass transmission is usually directly related to awg.
I also do not mix and match wires, and use the braided stuff for everything inside the amp and speakers.  In the system with the GK-1, I found a very noticeable improvement when I got rid of all the mixed wires and installed the braided stuff.

Steve

stvnharr

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Cables questions for AKSA gear
« Reply #38 on: 26 Aug 2005, 03:49 pm »
Andy,
I pretty much figured that the 50 footers were for a remote speaker setting where getting some sound was the main criteria.  I'm sure you'd agree that it's something of a compromise.

Optimal is a bit tricky, but in a 2 channel setup, used to just be called stereo, it's reasonably easy to have short cables.  In fact, when my amps were in mono cases,  I could have 1 meter IC's to amps, and 1 meter cables to speakers.

And as for cost, I've gravitated from Cardas Hex Golden, about $1k at half price dealer demo cost to my braided wire for less than $100.  The Cardas were on the warm side of sound.  The braided are very neutral and are big enough in awg to have all the bass.

In my experiences, I've found the biggest differences in speaker cables to be bass transmission, and, though some may differ in opinion, bass transmission is usually directly related to awg.
I also do not mix and match wires, and use the braided stuff for everything inside the amp and speakers.  In the system with the GK-1, I found a very noticeable improvement when I got rid of all the mixed wires and installed the braided stuff.

Steve

winterslove

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Cables questions for AKSA gear
« Reply #39 on: 27 Aug 2005, 01:31 am »
i happen to like naim cable as it is cheap and really
help my NON diy amp sound good
cable talk is another good cable
infact i tried qed gensis(bad speller) and it sounded
the same as the cable talk yet the qed was £30per meter and cable talk was £2.50
i then hooked up the qed to my naim and it sounded 100% better then the naim cable,yet with the mf the naim sounded better then the qed
so i suppose it comes down to the system you use the cable on
as otherwise why would one cable sound good with one system and bad with another
but then my brother doesnt agree with me
so it also comes down to ones own hearing

but for me
i will only use cable talk and naim as to my ears they are great.
and i can't wait to hook them up to my aska.



Jason