I'm running bi amped Exposure Super 18 power amps into a pair of Acoutic Energy AE1 mk2 speakers. I'm about to move my racks and will need longer lengths of cable (10m).
I understand my power amps are happier used with a high inductance, high impedamce cable, (I think that they don't have a Zobel network on the output, but don't quote me on this).
I'm currwntly running 24 yr old Linn LK20 for bass and Gale ? silvered for top, but these cables will be to short for my new location in any case.
I'm happy to spend sensible money on cables but not looking at crazy uber wires costing over £5 per metre, esp given lengths required.
Any cable recommendations?
Do I need to worry so much about what I use for the tops?
What in speaker cable terms are considered to be high capacitance and impedance values so I can check Blue Jeans, RS etc?
Any suggestions or advice for suitable cables would be appreciated. Bear in mind I'm no techie.
I understand my power amps are happier used with a high inductance, high impedamce cable, (I think that they don't have a Zobel network on the output, but don't quote me on this).
I'm currwntly running 24 yr old Linn LK20 for bass and Gale ? silvered for top, but these cables will be to short for my new location in any case.
I'm happy to spend sensible money on cables but not looking at crazy uber wires costing over £5 per metre, esp given lengths required.
Any cable recommendations?
Do I need to worry so much about what I use for the tops?
What in speaker cable terms are considered to be high capacitance and impedance values so I can check Blue Jeans, RS etc?
Any suggestions or advice for suitable cables would be appreciated. Bear in mind I'm no techie.
The resistance is of no concern from the amp's "point of view" but it will have a small effect on the FR of the speaker if it deviates much from the R that the speaker was designed for.
A low capacitance/high inductance cable is easily made by running any two conductors separeted by an inch or two from eachother.
/Peter
A low capacitance/high inductance cable is easily made by running any two conductors separeted by an inch or two from eachother.
/Peter
inductance causes the highs to roll off, impedance adds resistance, throwing away energy as heat. There is nothing good about a cable with high inductance and high impedance. A cable should have low inductance, low impedance, and low capacitance.
My personal opinion after lots of experimenting is that you should be smart, but expensive cable isn't really needed. I found benefit of using shielded speaker cables, or minimally, 4 wire twisted designs to cancel radiation. Speaker cables carry a lot of voltage and current as compared with other wires, and thus will create greater radiation, like power cables. They won't likely pickup radio signals or other forms of emi, but they will produce it, and if you have things like low level signal cables running along them, it might be beneficial to shield one from the other.
My favorite cheap speaker cable is to buy a few rolls of teflon coated silver plated copper wire from surplus shops, and twist my own. Last time I bought some I was able to buy 500 foot spools of 16 gauge wire for 18 cents a foot, and 20 gauge for 10 cents a foot. I use connectors I bought on Ebay from a chinese supplier, they are identical to the many "high quality " connectors offered by other manufacturers, and work fine. I twist it all together, put a few pieces of heat shrink to hold it all in place, solder on some connectors, and I'm set. I've been dumb and purchased cotton coated copper wire, silver wire, audioquest, cardas, and Kimber Kable and never found a big difference in sound.
Another cheap ready to go option is to buy a 4 wire power cable from the hardware store and use that. Or you could use a 3 cable wire and cut off the plugs, then connect ground and neutral together as the "-" connector, and the hot for "+", as thats a cheap and commonly suggested DIY option. I don't like that it's not symmetrical, call it an OCD thing, so I think buying a 4 cable wire, which they often have for 20-30 amp multiphase cables, and use that instead. Belden also makes a nice speaker cable with similar construction, but they often charge too much. It's the same thing as Bluejean cables sells, but in 4 conductor version. Grey pvc exterior, and red, black, white, and I think green for the conductors. It's a nice cable though, and large 500 foot spools brings the price down, but then, what do you do with the rest.
My personal opinion after lots of experimenting is that you should be smart, but expensive cable isn't really needed. I found benefit of using shielded speaker cables, or minimally, 4 wire twisted designs to cancel radiation. Speaker cables carry a lot of voltage and current as compared with other wires, and thus will create greater radiation, like power cables. They won't likely pickup radio signals or other forms of emi, but they will produce it, and if you have things like low level signal cables running along them, it might be beneficial to shield one from the other.
My favorite cheap speaker cable is to buy a few rolls of teflon coated silver plated copper wire from surplus shops, and twist my own. Last time I bought some I was able to buy 500 foot spools of 16 gauge wire for 18 cents a foot, and 20 gauge for 10 cents a foot. I use connectors I bought on Ebay from a chinese supplier, they are identical to the many "high quality " connectors offered by other manufacturers, and work fine. I twist it all together, put a few pieces of heat shrink to hold it all in place, solder on some connectors, and I'm set. I've been dumb and purchased cotton coated copper wire, silver wire, audioquest, cardas, and Kimber Kable and never found a big difference in sound.
Another cheap ready to go option is to buy a 4 wire power cable from the hardware store and use that. Or you could use a 3 cable wire and cut off the plugs, then connect ground and neutral together as the "-" connector, and the hot for "+", as thats a cheap and commonly suggested DIY option. I don't like that it's not symmetrical, call it an OCD thing, so I think buying a 4 cable wire, which they often have for 20-30 amp multiphase cables, and use that instead. Belden also makes a nice speaker cable with similar construction, but they often charge too much. It's the same thing as Bluejean cables sells, but in 4 conductor version. Grey pvc exterior, and red, black, white, and I think green for the conductors. It's a nice cable though, and large 500 foot spools brings the price down, but then, what do you do with the rest.
Yup but that can be compensated in the speaker and if you have an amp without output filtering you may not have a choice unless you want to see your amp go up in smoke and possibly take the speakers with it.
Impedance doesn't add resistance, impedance is the sum (with some phase angle) of reactance and resistance.
No big difference since the speaker load will be the dominant load. If you conncect 0.1ohm or 0.01ohm in series with 8ohm doesn't make a significant difference except for some small change of system Q and frequency response.
A cable should have parameters that makes it suitable for the specific job. In this case it's about keeping the amp alive!!
/Peter
ok but high impedance means high resistance at various frequency.
I don't see how a cable with a high impedance will keep an amp alive, the load of the speakers will be much higher. As for inductance, same thing, how does the inductance of the cable have any effect above and beyond that of the speaker? Is it parallel inductance people are concerned with?
Inductance causes rising resistance in reaction to frequency, it won't cause amp instability, but I dont see it as a good thing.
I thought most of the oscillation issues in amps was caused by high capacitance? no?First watt Nelson Pass article
That article indicates, as I said, that low inductance and low impedance is important, that the opposite is not desirable.
I don't see how a cable with a high impedance will keep an amp alive, the load of the speakers will be much higher. As for inductance, same thing, how does the inductance of the cable have any effect above and beyond that of the speaker? Is it parallel inductance people are concerned with?
Inductance causes rising resistance in reaction to frequency, it won't cause amp instability, but I dont see it as a good thing.
I thought most of the oscillation issues in amps was caused by high capacitance? no?First watt Nelson Pass article
That article indicates, as I said, that low inductance and low impedance is important, that the opposite is not desirable.
Thanks for those quick respopnses.
Pipoes
You say 'There is nothing good about a cable with high inductance and high impedance. A cable should have low inductance, low impedance, and low capacitance'.
In a review of my power amps I read 'Apparently the design of all Exposure amps require cables that have both a high capacitance and high inductance'.
Quote talen from http://www.soundstage.com/mike02.htm
All adds to the confusion. Any comments on this discrepancy welcomed. I must say that my current cables seem to sound fine and would re-use them if they'd stretch.
I need to go away and read some DIY twisting recipes when I've understood this inductance/impedance thing.
Shielded cables are an attractive idea, but dont they tend to use a solid core and stranded wires too. Any non symettrical worries there?
I should manage to avoid running speaker cable alongside mains cables completely, though they will run parallel to a scart TV feed, 1 unbalanced line cable and 2 subwoofer cables for 4 or 5m (all shielded). I think this is about as good as I can get it.
All termination will be by banana plugs, but they take fairly thick cables and can be stacked if needed.
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New posts came in while editing this. A little techie from Pan but I'll read carefully a few times.
Pipoes
You say 'There is nothing good about a cable with high inductance and high impedance. A cable should have low inductance, low impedance, and low capacitance'.
In a review of my power amps I read 'Apparently the design of all Exposure amps require cables that have both a high capacitance and high inductance'.
Quote talen from http://www.soundstage.com/mike02.htm
All adds to the confusion. Any comments on this discrepancy welcomed. I must say that my current cables seem to sound fine and would re-use them if they'd stretch.
I need to go away and read some DIY twisting recipes when I've understood this inductance/impedance thing.
Shielded cables are an attractive idea, but dont they tend to use a solid core and stranded wires too. Any non symettrical worries there?
I should manage to avoid running speaker cable alongside mains cables completely, though they will run parallel to a scart TV feed, 1 unbalanced line cable and 2 subwoofer cables for 4 or 5m (all shielded). I think this is about as good as I can get it.
All termination will be by banana plugs, but they take fairly thick cables and can be stacked if needed.
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New posts came in while editing this. A little techie from Pan but I'll read carefully a few times.
the issue isn't that a speaker cable will pickup emi, that is unlikely at the signal level that travels through speaker cable, it's that it produces emi of it's own which can interfere with lower level signals. It's really a minor issue, but if you have rca cables, digital coaxial interconnects, even scart cables in the vicinity of a speaker cable, there is a chance that it could introduce some interference. The digital and scart will work at different frequencies, and should be well shielded, so it probably is less of an issue with those.
Well if you read the report I linked from First Watt, it talks about actual tests they did. There are other tests like those on the web. I think the review has it reversed, high capacitance appears to be what causes the oscillation, unless I misread the article.
Well if you read the report I linked from First Watt, it talks about actual tests they did. There are other tests like those on the web. I think the review has it reversed, high capacitance appears to be what causes the oscillation, unless I misread the article.
Well, after searching the threads here for help before my OP and coming up blank, guess what. Googled a query and got this very useful link.
here http://www.avforums.com/forums/hi-fi-systems-separates/510637-exposure-amps-cable-dilema.html
Now, one interesting quote in particular
'I have emailed the product designer at Exposure and he couldn't see any problem. He did mention that I should try and use high inductance and low capacitance cable but as I don't have a clue what thet means I'll continue to use the QED XT-400. He said the best way to see if the cable was the wrong type is the amp will get hot'.
Note the designer says 'high inductance and low capacitance cable'. Does this make more sense?
For anybody who bothers to read the above thread, the Linn K20 cable I use at present is exactly the same as the Naim? cable with different printing. My amps stay stupidly cool even when driven hard. I must be doing something right.
The fog is lifting, I'm getting it. I think.
here http://www.avforums.com/forums/hi-fi-systems-separates/510637-exposure-amps-cable-dilema.html
Now, one interesting quote in particular
'I have emailed the product designer at Exposure and he couldn't see any problem. He did mention that I should try and use high inductance and low capacitance cable but as I don't have a clue what thet means I'll continue to use the QED XT-400. He said the best way to see if the cable was the wrong type is the amp will get hot'.
Note the designer says 'high inductance and low capacitance cable'. Does this make more sense?
For anybody who bothers to read the above thread, the Linn K20 cable I use at present is exactly the same as the Naim? cable with different printing. My amps stay stupidly cool even when driven hard. I must be doing something right.
The fog is lifting, I'm getting it. I think.
High inductance = lowpass filter. As long as the inductance doesn't effect frequency response, it can act as a safeguard against HF oscillations in an amplifiers output stage. Of course, the amplifier should have been designed with this in mind from the start.
I seem to remember Spectral's wide bandwidth amps having problems with certain cables, but I can't remember what the properties were that made them unhappy.
I seem to remember Spectral's wide bandwidth amps having problems with certain cables, but I can't remember what the properties were that made them unhappy.
pjpoes said:
Nope! Possibly you are thinking right but your statement is not correct. High resistance is not a necessity for high impedance.
Nope. Not at high frequencies.
Nope, parallel capacitance.
With low capacitance comes high inductance.
Nope, series inductance casue rising impedance towards higher frequencies.
Capcitance can be said to be the problem but inductance as well since these two reactive phenomena forms resonant circuits.
For an amp that is stable (typically with an output filter which not all amps have) and a typical speaker load yes, low resistance and low inductance is usually good.
/Peter
I think I've read before that there ends up being issues with designing a cable to be low capacitance, namely it raises the inductance. Capacitance typically is so low that it has little impact on frequency, so often inductance and impedance were the main goals focused on, and the tradeoff (if I read the Nelson Pass article right) was cables with high capacitance. It appears that it is parallel capacitance in the cable that causes stability problem. This is not a common trait in normal cables, I think it's an issue more common in some of the various exotic cables out there. I still stand by that inductance is not a good thing, I'm not sure what they consider inductance, but as mentioned above, high inductance means high pass filter. If nothing else, it's going to modify the response of the speaker, and I can't see that as a good thing. I can't see how inductance would keep an amp from oscillating, per say. Is the issue that when the signal travels from the amp to the speaker, hit's the speakers, say 8 ohm impedance, some of it travels back down the speaker cable, and the high inductance helps to filter this out? If that's the case, then again, I think this implies a design problem.
My best guess is that they are suggesting the idea that if a cable is low in capacitance, it will likely be higher in inductance. The inductance is still quite low though.
My best guess is that they are suggesting the idea that if a cable is low in capacitance, it will likely be higher in inductance. The inductance is still quite low though.
i would refer the OP to this thread for all of the conflicting views on cables ( speaker and connect )
http://www.diyaudio.com/forums/showthread.php?threadid=15600&highlight=
AFAIAC the only important thing is keeping the DCR as low as is reasonable.
I use the cheap DIY option of 240V power cable as described for party boxes as it is tough and cheap, and home made 3 or 4ply plaited but 2.5mm> seems to me to be fine up to 25 or 30 meters.
3ply plaited with a nonconducting center seems to work for me, using good quality 2.5mm> separated and then plaited, you need about 30% more length of wire than the length of cable needed as the plaiting shortens the run
http://www.diyaudio.com/forums/showthread.php?threadid=15600&highlight=
AFAIAC the only important thing is keeping the DCR as low as is reasonable.
I use the cheap DIY option of 240V power cable as described for party boxes as it is tough and cheap, and home made 3 or 4ply plaited but 2.5mm> seems to me to be fine up to 25 or 30 meters.
3ply plaited with a nonconducting center seems to work for me, using good quality 2.5mm> separated and then plaited, you need about 30% more length of wire than the length of cable needed as the plaiting shortens the run
Cheers for the response Moondog (a damn fine fellow he was too, I was listening to Elpmas only last week).
I'm well aware of the cable debates that have been ongoing for decades now. I'm not convinced of massive differences and won't pay crazy 'snake oil' prices.
A good contact at each end, and sensible cheapish cable is what I'm after.
My question really ariose from the slightly odd nature of my amps output.
Since my existing bass cable is of the sort the manufacturer recommends, sounds fine to me, and causes my amp no heating stress, I'm looking for something similar but without the price tag. Having said that, it cost me £2m in 1987, so isn't that bad a rip off when you look at it's lifetime. At any rate I should be able to DIY it cheaper than buying a brand.
I'm well aware of the cable debates that have been ongoing for decades now. I'm not convinced of massive differences and won't pay crazy 'snake oil' prices.
A good contact at each end, and sensible cheapish cable is what I'm after.
My question really ariose from the slightly odd nature of my amps output.
Since my existing bass cable is of the sort the manufacturer recommends, sounds fine to me, and causes my amp no heating stress, I'm looking for something similar but without the price tag. Having said that, it cost me £2m in 1987, so isn't that bad a rip off when you look at it's lifetime. At any rate I should be able to DIY it cheaper than buying a brand.
pjpoes said:
That is an invalid generalization. What you say does apply to a large subset of current hifi.
What is imprtant is a synergy between amplifier, wire, and the speakers you have connected.
My speakers for instance prefer an amplifier with a hignish output impedance, don;t mibd cables with high resistane and inductance.
The Exposure amplifier designer (i assume) like Julian Vereker of Naim, choose to leave the explicit LC filter out of the amplifier, instead choosing to specify a specific length and kind of cable as a substitute. This is done because it was/is felt that it leads to better sonics.
Read these 2 much more recent papers by Nelson:
http://www.firstwatt.com/downloads/cs-amps-speakers.pdf
http://www.firstwatt.com/downloads/cs-xover-networks.pdf
dave
RF oscillation!
I see that no one has added to this thread for a long time, but there is another relevant point to mention: Some amps, if they have a wide bandwidth and low or zero feedback, can oscillate at RF frequencies if fed into a high-capacitance load. This can fry the amp if it happens. Since capacitance and inductance are inversely correlated in speaker cables, that may be the reason for the caution regarding the amplifier.
I see that no one has added to this thread for a long time, but there is another relevant point to mention: Some amps, if they have a wide bandwidth and low or zero feedback, can oscillate at RF frequencies if fed into a high-capacitance load. This can fry the amp if it happens. Since capacitance and inductance are inversely correlated in speaker cables, that may be the reason for the caution regarding the amplifier.
This thread is better off dead; a mishmash of peculiar ideas.
With OP's issue of a 30 foot run to the speakers, it is slightly possible that the wire resistance might be worth avoiding getting too high. But the reactance values are so tiny in speaker wires such as ordinary domestic lamp zip cord, hardly worth fussing about.
Anyway, once you stick one of those old-time passive crossovers in the line, you're stuck with an awful load for the amp and who-knows-what damping factor looking backwards.
B.
Historic footnote: some of the super Kenwood Basic amps of the 1980s had remote sensing wires that connected the speaker terminals back with the amp's feedback network (in addition to the power wires). That way the amp "knew" what was getting through and the DF benefitted. Now that's super.
With OP's issue of a 30 foot run to the speakers, it is slightly possible that the wire resistance might be worth avoiding getting too high. But the reactance values are so tiny in speaker wires such as ordinary domestic lamp zip cord, hardly worth fussing about.
Anyway, once you stick one of those old-time passive crossovers in the line, you're stuck with an awful load for the amp and who-knows-what damping factor looking backwards.
B.
Historic footnote: some of the super Kenwood Basic amps of the 1980s had remote sensing wires that connected the speaker terminals back with the amp's feedback network (in addition to the power wires). That way the amp "knew" what was getting through and the DF benefitted. Now that's super.
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