Power Cables to stir pots with

[ttocs]

I know I'm late to the party, but I just made my first power cable, for my Krell S1500 amp, and wanted to post the results.

Home Depot 20A wall plug $10.

HiFiKing CC-18(Cu) Red Copper Series IEC Plug Connector 15A/125V $12, it grips the prongs on the amp almost as well as the hospital outlet grips the wall plug.

Cable Matters 14AWG/4 speaker wire (paired two wires together for each of the Load and Common so those are effectively 11 gauge each, added a 5th wire for Ground so that's only 14 gauge), already had lots of wire left on the spool.

Compared to the 10A stock cable (yes it's a 10A power cable for a 15A required amp, I think the dealer gave me the wrong cable), the DIY cable has the following measured differences:
Same capacitance
Less Henrys
Less impedance resistance

Also, when using the pink noise Levels on XMC-1, with the DIY cable the measured audio is 1dB higher (repeated 6 times back and forth to be sure).

The main reason I wanted to make a power cable for my amp was to see if any difference could be measured or heard. As good as the audio has been for a long time, I've wondered if the high treble could be smoothed some more without losing treble. I've never even looked at the cable that came with the amp before, but I should have done so before this.

I bought the floor model amplifier and the cable that I was given is a 10A cable. This amp requires a dedicated 15A outlet so I would expect the cable to at least be rated at higher than 10 amps. Ok, at least if I make a power cable then I can get better quality plugs and be satisfied that it'll be made using thicker gauge wire. The wall outlet is a dedicated 20A hospital grade which has a really strong bite on the plug so that end of the power cable has a good connection. The amp side stock cable has a "normal" amount of bite, which is nowhere near as good so I bought a really good IEC connector with a very strong bite.

As mentioned above, the measurements show the physical differences. There are audible differences also. I dislike using some of the adjectives to follow because it can give the impression that the system is not very listenable, quite the contrary, but there always seems to be room for improvement. Crashing cymbals sound less harsh, sibilance in recordings is less shrill, both of which can be easily picked out while auditioning The Hamburger Concerto by Focus. These are the same differences I experienced when searching for a preamp to mate with the Krell amp but it was even more obvious at the time until I found the XMC-1. Little details that have been lost for a long time are back in the song Never As Good As The First Time by Sade. These are things anybody with decent hearing would be able to hear. This album by Focus is one I use to demo equipment because it has a lot of complex sounds which can very quickly overwhelm a system with problems, but with a good setup sounds wonderful. The sound is also a bit fuller, smoother.

The soundstage on my system was already great, so no change there. No other differences to report. 

I think the major differences in the cables are: proper gauge wire and better bite on the IEC connector on the back of the amp. I'll probably try shielding just because noise rejection is always a good thing to strive for.

Full disclosure, my speaker wires are from the same spool of wire I used for the power cable, and my XLR interconnects are DIY as well using Switchcraft XLRs and shielded 22AWG 3wire cable from Home Depot.

No smoke, and I only use mirrors when setting up sound panels.


edit: I'm not recommending properly sized power cables be replaced, just the ones like mine that were obviously not adequate. So those power cables that cost $6,000 for a 3' length seem a tad overpriced.

[405x5]

Dec 13, 2018 20:00:43 GMT -5 ttocs said:

I know I'm late to the party, but I just made my first power cable, for my Krell S1500 amp, and wanted to post the results.

Home Depot 20A wall plug $10.

HiFiKing CC-18(Cu) Red Copper Series IEC Plug Connector 15A/125V $12, it grips the prongs on the amp almost as well as the hospital outlet grips the wall plug.

Cable Matters 14AWG/4 speaker wire (paired two wires together for each of the Load and Common so those are effectively 11 gauge each, added a 5th wire for Ground so that's only 14 gauge), already had lots of wire left on the spool.

Compared to the 10A stock cable (yes it's a 10A power cable for a 15A required amp, I think the dealer gave me the wrong cable), the DIY cable has the following measured differences:
Same capacitance
Less Henries
Less impedance

Also, when using the pink noise Levels on XMC-1, with the DIY cable the measured audio is 1dB higher (repeated 6 times back and forth to be sure).

The main reason I wanted to make a power cable for my amp was to see if any difference could be measured or heard. As good as the audio has been for a long time, I've wondered if the high treble could be smoothed some more without losing treble. I've never even looked at the cable that came with the amp before, but I should have done so before this.

I bought the floor model amplifier and the cable that I was given is a 10A cable. This amp requires a dedicated 15A outlet so I would expect the cable to at least be rated at higher than 10 amps. Ok, at least if I make a power cable then I can get better quality plugs and be satisfied that it'll be made using thicker gauge wire. The wall outlet is a dedicated 20A hospital grade which has a really strong bite on the plug so that end of the power cable has a good connection. The amp side stock cable has a "normal" amount of bite, which is nowhere near as good so I bought a really good IEC connector with a very strong bite.

As mentioned above, the measurements show the physical differences. There are audible differences also. I dislike using some of the adjectives to follow because it can give the impression that the system is not very listenable, quite the contrary, but there always seems to be room for improvement. Crashing cymbals sound less harsh, sibilance in recordings is less shrill, both of which can be easily picked out while auditioning The Hamburger Concerto by Focus. These are the same differences I experienced when searching for a preamp to mate with the Krell amp but it was even more obvious at the time until I found the XMC-1. Little details that have been lost for a long time are back in the song Never As Good As The First Time by Sade. These are things anybody with decent hearing would be able to hear. This album by Focus is one I use to demo equipment because it has a lot of complex sounds which can very quickly overwhelm a system with problems, but with a good setup sounds wonderful. The sound is also a bit fuller, smoother.

The soundstage on my system was already great, so no change there. No other differences to report. 

I think the major differences in the cables are: proper gauge wire and better bite on the IEC connector on the back of the amp. I'll probably try shielding just because noise rejection is always a good thing to strive for.

Full disclosure, my speaker wires are from the same spool of wire I used for the power cable, and my XLR interconnects are DIY as well using Switchcraft XLRs and shielded 22AWG 3wire cable from Home Depot.

No smoke, and I only use mirrors when setting up sound panels.


edit: I'm not recommending properly sized power cables be replaced, just the ones like mine that were obviously not adequate. So those power cables that cost $6,000 for a 3' length seem a tad overpriced.

I like that title “to stir pots with”!
Beyond what ships with the equipment, that’s all they’re good for.

Bill

[ttocs]

Bill, you found my stirring diatribe!

In my case I'm positive the wrong cable was given to me when I bought this floor model amp. I never thought to suspect a power cable, but it's 18 gauge! not the expected 14 gauge.

One more difference is that the amp is running cooler. I've been running a computer fan at slow speed for the last couple years on top of the hottest part of the amp, and even with the fan, at the volume I've got it at right now, it would be hot enough to be uncomfortable to leave my hand on top. Now, it's luke warm which means I may get rid of the fan.

If I was given the correct cable I would not have had an interest in replacing it. I gotta say, it's like a whole 'nother upgrade! I think the biggest problem with the crummy cable I've had for the last 5 years is the resistance.

At much higher volume than I'm used to listening at the sound is actually much better. Don't get me wrong though, I can't imagine a noticeable difference between what I now am experiencing and using a $6,000 power cable.

During the time I've been writing this I turned up the volume of Sade even more, over 95 dB, and it's intoxicating! Simply wonderful! And the amp is still only luke warm, amazing!! Normally at any volume close to this it would tend to get a bit brash.

Back to enjoying . . . . . .

[novisnick]

I’ve been experimenting with cables the past few months, all types of them and have come to the conclusion that one should start at the power cable and work towards the speaker in the replacement order. Especially if you have the ability to try multiple cables at each stage. That way you’ll be better able to tell which has the most positive outcome.
Experimenting with cables has taught a few of us that the construction, size, twist and sheathing can and do in many cases make a difference.
Many may scoff or laugh but Hey! Its My money and My ears! 😁
Anything is only as good or poor as its weakest link. Cabling has the most links in my system so it makes a significant difference.
The cumulative improvements are well worth the cost. Even if your system or ears finds no improvement, the knowledge of knowing any problem you may someday have shouldn’t be traced back to a cable ot wire.
Im Not suggesting anybody spend $500. On a $1K system. That wouldn’t be prudent. But if you spent multiple thousands you at least owe it to yourself, ears and system to upgrade cabling.

[Boomzilla]

Hi ttocs -

I enjoyed the review and particularly the fact that you identified the components you used to make that cable. I recently tried a "pot-stirrer" Pangea cable with my Emotiva PA-1 amps. But for whatever reason (good stock cords? Low power consumption?) I didn't find an audible difference. I could easily see, however, that a high-current device like your Krell would more readily show the difference.

Boom

[AudioHTIT]

I think if you to measured a 1 dB difference in output by changing power cables, there must be something wrong with the test, the settings, or the equipment. I know you repeated it, but 1 dB is pretty big, especially if you’re within the normal operating limits of the equipment. Are you measuring electrically (voltage at preamp or amp) or acoustically (mic in room)? With the later there are many potential variables, with the former it seems very unlikely. Could you list the test method, levels, etc? Maybe we could get a better idea of how such a difference could occur.

[mgbpuff]

The Krell amp has a 12A slow blow fuse, and since plug in wall cables are in free air, they have a higher current rating than the in conduit or in wall ratings out of the NEC. So don't say that the dealer gave you the wrong cable because that is not true. As for your testimony that your cable makes a sound improvement, well we will have to take your word on that. Also, why would you use speaker wire for power purposes? Speaker wire is rated and insulated for lower voltage/power limited circuits - basically this may be unsafe.

[405x5]

Dec 13, 2018 23:23:12 GMT -5 ttocs said:

Bill, you found my stirring diatribe!

In my case I'm positive the wrong cable was given to me when I bought this floor model amp. I never thought to suspect a power cable, but it's 18 gauge! not the expected 14 gauge.

One more difference is that the amp is running cooler. I've been running a computer fan at slow speed for the last couple years on top of the hottest part of the amp, and even with the fan, at the volume I've got it at right now, it would be hot enough to be uncomfortable to leave my hand on top. Now, it's luke warm which means I may get rid of the fan.

If I was given the correct cable I would not have had an interest in replacing it. I gotta say, it's like a whole 'nother upgrade! I think the biggest problem with the crummy cable I've had for the last 5 years is the resistance.

At much higher volume than I'm used to listening at the sound is actually much better. Don't get me wrong though, I can't imagine a noticeable difference between what I now am experiencing and using a $6,000 power cable.

During the time I've been writing this I turned up the volume of Sade even more, over 95 dB, and it's intoxicating! Simply wonderful! And the amp is still only luke warm, amazing!! Normally at any volume close to this it would tend to get a bit brash.

Back to enjoying . . . . . .

If they gave you the wrong cord then of course I agree with you. Certainly that could compromise the amplifier.

Bill

[ttocs]

Dec 14, 2018 9:45:55 GMT -5 AudioHTIT said:

I think if you to measured a 1 dB difference in output by changing power cables, there must be something wrong with the test, the settings, or the equipment. I know you repeated it, but 1 dB is pretty big, especially if you’re within the normal operating limits of the equipment. Are you measuring electrically (voltage at preamp or amp) or acoustically (mic in room)? With the later there are many potential variables, with the former it seems very unlikely. Could you list the test method, levels, etc? Maybe we could get a better idea of how such a difference could occur.

I did the test acoustically, yes problematic. The meter fluctuates but I could see a definite difference in the max/min/average numbers bouncing around. I used a SPL meter (cheapy) aimed up at the sweet spot. After the first comparo I just enjoyed for a bit, then my mind got the better of me and I kept checking the measurements I'd done previously. Then I kept swapping the power cables pretty much as quickly as the system could reboot - everything had been running for over 30 minutes by this time and the "off" time was only about a minute.

I will play with measuring the voltage over the weekend. How would you recommend this measurement be done?

edit: keep in mind that there was a problem, the cable that was supplied by the dealer was the WRONG cable. Wrong AWG.

[mgbpuff]

"edit: keep in mind that there was a problem, the cable that was supplied by the dealer was the WRONG cable. Wrong AWG." So you say! The current rating of a wire depends on a combination of the gauge of the wire, the temperature rating of it, and the dielectric property of its insulation to withstand voltage differentials. I have only seen these properties and 3rd party stamps on any type of extension cord, not amperage. Plus the fusing in your amp is less than even 15amps. Did you read my previous post?

[KeithL]

A few notes on power cables and amplifiers.

The main thing that matters with power cables on amplifiers is that the cable is heavy enough.
If the cable is too thin, it will have too much resistance, which may limit the power the amplifier can deliver.

The way this works is that a thin cable has a lot of resistance.

Every cable has some resistance, and resistance  creates a voltage drop proportional to the current you draw.

So, for example, if your amplifier is 100 ft from your breaker box, the wires in the walls will have some resistance.

Because of this resistance, under heavy load, the voltage at the power inlet of the amplifier will be a few volts lower than the voltage at your breaker box.

A thin six foot power cable could end up causing as much voltage drop as 100 ft of the heavy gauge wire used for house wiring.

However, as far as the amplifier is concerned, the biggest effect is the same as if your line voltage was simply lower.

USUALLY, what will happen is that the maximum amount of power your amp can deliver will be slightly lower (possibly as much as 5% to 10%).

So your amplifier that's rated at 300 watts may instead clip at 290 watts.

With most modern amplifier designs the gain will remain the same - but the maximum power before clipping will simply be reduced a little bit.

A smaller issue is that the source impedance of the power line is also effectively raised.

This may cause performance issues for some amplifiers - but they should be minimal.

A six foot 18 gauge power cable - compared to a 14 gauge one the same length - is more or less equivalent to moving your amplifier an extra 50 or 75 feet away from the breaker box.

(It's not great but it shouldn't be tragic either.)

However, considering that a nice commercial 14 gauge power cable can be had for less than $15, there's really no reason to skimp.

I should also note that some devices, especially preamps and DACs, MAY ship with a shielded power cable.

The purpose is both to keep noise from entering the power cable from outside, and to keep noise produced by the device from radiating out, where it may bother something else.

With most equipment it really doesn't make much difference.

HOWEVER, it is more common to see thin power cables that are shielded than thick ones.

And equipment like preamps, which draws very little power, doesn't NEED a heavy cable.

(The point is that, while it probably won't matter, replacing a thin shielded power cable with a fat unshielded one, on something like a preamp, might be a slight step DOWN rather than up.)

I would agree, though, that 18 gauge is an excessively thin cable for a power amp......

[DYohn]

I have some 0000 AWG cable that is more than stiff enough to stir a pot with.

[adaboy]

Dec 14, 2018 13:18:05 GMT -5 DYohn said:

I have some 0000 AWG cable that is more than stiff enough to stir a pot with.

Will need that for each neutral, hot, and ground plz. Oh and directly from the transformer. No need in wasting any amperage lol.

[DYohn]

Dec 14, 2018 13:40:43 GMT -5 adaboy said:

Dec 14, 2018 13:18:05 GMT -5 DYohn said:

I have some 0000 AWG cable that is more than stiff enough to stir a pot with.

Will need that for each neutral, hot, and ground plz. Oh and directly from the transformer. No need in wasting any amperage lol.

In car audio it's just hot and ground, so less copper required.

[Casey Leedom]

Wow. "0000 AWG == 0.46" inches in diameter ... :-)

Casey

[mgbpuff]

I missed where he said that it was 18 gauge. Even zip cord is usually 16 gauge. Sounds like he was given a source component power cable instead of the power amp cable. I would have changed it out also. But my caution about using speaker wire for power applications is still valid observation.

[ttocs]

Dec 14, 2018 9:50:39 GMT -5 mgbpuff said:

The Krell amp has a 12A slow blow fuse, and since plug in wall cables are in free air, they have a higher current rating than the in conduit or in wall ratings out of the NEC. So don't say that the dealer gave you the wrong cable because that is not true. As for your testimony that your cable makes a sound improvement, well we will have to take your word on that. Also, why would you use speaker wire for power purposes? Speaker wire is rated and insulated for lower voltage/power limited circuits - basically this may be unsafe.

You are correct about the fuse, 12A slow blow. The in-wall electric wires in my house are in metal conduit, no Romex allowed here.

The power cable handed to me for my floor model demonstrator amp is 18AWG rated for 10A. The IEC connector has a lock on it that does not mate to anything on the amp which has no locking feature. My contention is that the cable is for a different device. If someone else with a Krell amp can confirm the gauge of their power cable, preferably from a similar era 15A amplifier, it would be greatly appreciated. I will repeat my claim, the dealer supplied the wrong cable when he went into the back room to look for a power cable. This amp was used for demo purposes, then sent to Krell to be upgraded from 3 channel to 5 channel, then put out for sale on a shelf with no power cable, no box, no instructions. The salesman had to look for a power cable. I can't otherwise complain because it was a steal, has a 5 year warranty which was used when Krell replaced all the capacitors and did an update mod for a known issue.

You are also correct about improper usage of wires. This cable is CL2 rated for voltage surges up to 150 volts. I am taking the short term risk while learning about the power cable subject. Experimenting with other wires will include 12 gauge extension cord wire, 12 gauge THHN solid and stranded. I highly doubt any other wire of approximately equal gauge will make a difference in sound so long as the electrical measurements are the same, resistance, inductance, (I've read that for electrical usage capacitance is not an issue when providing power to a device like a audio amp, I don't recall why).

For the most part, I used what I had on hand and only bought what I didn't have initially. Since the amp is operating at a much cooler operating temperature I conclude that the wire is not exhibiting any negative qualities while providing power to the amp. I would however be concerned with long term duty based solely on the insulating material not being rated for continuous 120V usage and when it might begin to break down.

If you can provide nifty ways to measure before/after tests using test equipment I hopefully have on hand, that would be great. I'm always interested in being able to measure things to see why something is different.

[ttocs]

Also, I agree with Keith that there are inexpensive power cables out there. At this point I gotta say that the IEC connector I got is really, really nice in how well it grips the spades on the amp.

The two measurements I think are key in this case are Resistance and Inductance, both of which are lower than the 18 gauge cable.

So I'm left with the main question and some follow-ups: Why is the amp's operating temperature much lower? 

Is this because the resistance is lower? the inductances is lower? or both? Or does the grippier IEC connector contributing as well?

My initial answer without any facts to back it up is: Yes

[DYohn]

The amplifier will draw what it draws. An under-sized power cable will heat up more than one designed with sufficient ampacity. If the power cable introduces enough resistance it will lower the line voltage, causing the amp to demand even more current, and around and round we go. The amp does not care it will just demand the current it needs, and the power cable will deliver that current right up to the point where it burns up. The only thing electrically that a larger power cable will do is deliver the demand current with fewer line losses and less heat due to losses.

[simpleman68]

Dec 14, 2018 13:18:05 GMT -5 DYohn said:

I have some 0000 AWG cable that is more than stiff enough to stir a pot with.

"That's what he said"

Somebody had to.....

Scott