Cable differences are real

[Hugo9000]

1 hour ago, fas42 said:

The biggie that is generally ignored is handling noise - yes, people will say this is too far down to matter, but every system I've been involved with has always needed this area to be considered. As an example, on the last visit to the local audio friend we lost quality at one stage - going in circles for a bit - then I noticed that an external cable had lost its normal spacing layer, because of interaction with the components.

 

I used to have tremendous difficulty maintaining the normal spacing layer between my cables as well.  Then one day, when my mother happened to mention to one of her Country/Primitive decorating club members that the twig wreath over her mantel was crafted from myrtlewood twigs, I knew I had the answer!  I carefully culled precious myrtlewood twigs from the wreath and used them to space my cables, using natural raffia to tie them in place.  I'm sure you can imagine the improvement this provided!

 

 

[fas42]

mansr wants this to be purely about FR, so won't disturb this further. However, every part of the construction of the cable and how they are configured could play a part in why "cable differences are real" ... just something to bear in mind ... .

[mansr]

OK, I'll reveal one more. #4 is the 10 m generic RCA.

[wgscott]

11 hours ago, Hugo9000 said:

 

 imagine the improvement 

 

 

Well-chosen words.

[March Audio]

On 1/6/2019 at 10:03 PM, mansr said:

Cable differences are real, and they can be measured. Rummaging through my cable box, I selected a few and measured their frequency response up to 125 MHz using white-ish noise.

 

These are the cables I used:

• RG-58 coax, 0.5 m, 4.8 mm outer diameter, black
• RG-58 coax, 2 m, 4.8 mm, black
• No-name cheap-looking single RCA, 5 m, 2.6 mm, black
• No-name not-quite-as-cheap dual RCA, 10 m, 2.8 mm, black with red/white plugs
• No-name video (yellow plugs) single RCA, 1 m, 2.8 mm, black
• Maplin Pro dual RCA, 0.75 m, 5.9 mm, black + black/grey braid
• Maplin Pro dual RCA, 3 m, 5.9 mm, black + black/grey braid
• Maplin (non-pro) single RCA, 1.5 m, 3.7 mm, black with black/blue plugs
• AudioQuest Tower dual RCA, 1 m, 4.7 mm, black with grey stripes
• iFi branded dual RCA, 0.5 m, 3.7 mm, purple
• 21 AWG zip cord, 13 m, 2.0 mm, black

 

Below are spectrum analyser screenshots for each of these cables, in random order. Your task is to guess which spectrum goes with which cable, as many or as few as you like. It's also OK to simply point and laugh at the more silly-looking ones. The noise generator spectrum is inherently a little rolled off, so bear that in mind.

 

1. 
2. 
3. 
4. 
5. 
6. 
7. 
8. 
9. 
10. 
11. 

 

Have fun!

For the benefit of the forum you need to buy a vna

 

https://www.keysight.com/en/pcx-x205189/ena-vector-network-analyzers-5-hz-to-20-ghz?cc=US&lc=eng

[Arpiben]

Fieldfox Handheld Keysight VNAs are if not more affordable at least less bulky.😉

 

[March Audio]

I am very familiar with the excellent Fieldfox.  Its more RF suited though. My background is instrumentation and spent time using and subsequently representing the Keysight range. 

[Audiophile Neuroscience]

2 hours ago, March Audio said:

For the benefit of the forum you need to buy a vna

 

https://www.keysight.com/en/pcx-x205189/ena-vector-network-analyzers-5-hz-to-20-ghz?cc=US&lc=eng

 

Over $15k (AUD) and doesn't even play music ! Crummy DAC if you ask me !

[March Audio]

15 minutes ago, Audiophile Neuroscience said:

 

Over $15k (AUD) and doesn't even play music ! Crummy DAC if you ask me !

Oh that's just the starting price, without essential options like cal kits. look further down. 

[The_K-Man]

Oooh yes, cable differences are definitely real - especially for runs over 1 mile/1.6km. Or using AWG22 or higher gauge wire for speakers vs a more common-sense AWG16. 😮

 

I'm looking more at source quality, values of production, mastering, than at the $100 vs $1 per foot factor.

[The_K-Man]

1 hour ago, The_K-Man said:

Oooh yes, cable differences are definitely real - especially for runs over 1 mile/1.6km. Or using AWG22 or higher gauge wire for speakers vs a more common-sense AWG16. 😮

 

I'm looking more at source quality, values of production, mastering, than at the $100 vs $1 per foot factor.

 

HOW is this 'off-topic'?   Ave Maria...

[mansr]

2 minutes ago, The_K-Man said:

HOW is this 'off-topic'?   Ave Maria...

The topic is the interconnect cables I tested, not speaker wire or music mastering.

[mansr]

I think we've waited long enough. Here's the list:

1. Maplin Pro dual RCA, 0.75 m, 5.9 mm, black + black/grey braid
2. iFi branded dual RCA, 0.5 m, 3.7 mm, purple
3. RG-58 coax, 2 m, 4.8 mm, black
4. No-name not-quite-as-cheap dual RCA, 10 m, 2.8 mm, black with red/white plugs
5. Maplin Pro dual RCA, 3 m, 5.9 mm, black + black/grey braid
6. RG-58 coax, 0.5 m, 4.8 mm outer diameter, black
7. No-name video (yellow plugs) single RCA, 1 m, 2.8 mm, black
8. AudioQuest Tower dual RCA, 1 m, 4.7 mm, black with grey stripes
9. 21 AWG zip cord, 13 m, 2.0 mm, black
10. Maplin (non-pro) single RCA, 1.5 m, 3.7 mm, black with black/blue plugs
11. No-name cheap-looking single RCA, 5 m, 2.6 mm, black

[marce]

Interesting results, apart from the cheapest cable (with probably 6 strands for the shield/return and a sub optimal cable it is interesting that the true audio cable is one of the worse, my faith in Audio cable marketing has just taken a severe blow...😀

Its been an interesting exercise, thanks.

[asdf1000]

15 minutes ago, mansr said:

I think we've waited long enough. Here's the list:

1. Maplin Pro dual RCA, 0.75 m, 5.9 mm, black + black/grey braid
2. iFi branded dual RCA, 0.5 m, 3.7 mm, purple
3. RG-58 coax, 2 m, 4.8 mm, black
4. No-name not-quite-as-cheap dual RCA, 10 m, 2.8 mm, black with red/white plugs
5. Maplin Pro dual RCA, 3 m, 5.9 mm, black + black/grey braid
6. RG-58 coax, 0.5 m, 4.8 mm outer diameter, black
7. No-name video (yellow plugs) single RCA, 1 m, 2.8 mm, black
8. AudioQuest Tower dual RCA, 1 m, 4.7 mm, black with grey stripes
9. 21 AWG zip cord, 13 m, 2.0 mm, black
10. Maplin (non-pro) single RCA, 1.5 m, 3.7 mm, black with black/blue plugs
11. No-name cheap-looking single RCA, 5 m, 2.6 mm, black

 

So conclusion is just keep length under 2m (as short as practicably possible) and you'll be fine ?

 

Except for that Audioquest result....

 

[tmtomh]

1 hour ago, mansr said:

I think we've waited long enough. Here's the list:

1. Maplin Pro dual RCA, 0.75 m, 5.9 mm, black + black/grey braid
2. iFi branded dual RCA, 0.5 m, 3.7 mm, purple
3. RG-58 coax, 2 m, 4.8 mm, black
4. No-name not-quite-as-cheap dual RCA, 10 m, 2.8 mm, black with red/white plugs
5. Maplin Pro dual RCA, 3 m, 5.9 mm, black + black/grey braid
6. RG-58 coax, 0.5 m, 4.8 mm outer diameter, black
7. No-name video (yellow plugs) single RCA, 1 m, 2.8 mm, black
8. AudioQuest Tower dual RCA, 1 m, 4.7 mm, black with grey stripes
9. 21 AWG zip cord, 13 m, 2.0 mm, black
10. Maplin (non-pro) single RCA, 1.5 m, 3.7 mm, black with black/blue plugs
11. No-name cheap-looking single RCA, 5 m, 2.6 mm, black

 

Very interesting! So the Audioquest wasn't 9 or 11, but I'm glad Audioquest hasn't fully let us down, since #8 has that bizarre, enormous dip! 🙂 What do you think causes that?

 

It's also interesting that - if I read the images right - the 1.5m and especially 3m Maplin cables' frequency responses are a bit more ragged than most of the others.

 

So in general, it seems to be:

 

- Shorter and coax cables look pretty good

- Mid-length Maplins look okay but not as good

- Audioquest and long cables look bad

 

Yes?

[Jud]

Can someone say why we should be looking for level response up to 125mHz, or am I reading the scale wrong?

[mansr]

22 minutes ago, tmtomh said:

It's also interesting that - if I read the images right - the 1.5m and especially 3m Maplin cables' frequency responses are a bit more ragged than most of the others.

That's largely down to impedance mismatches. The long Maplin has an impedance of about 75 Ω whereas the AFG and spectrum analyser are 50 Ω. This results in reflections which cause varying amounts of cancellation. An RG-59 coax looks similar.

[mansr]

22 minutes ago, Jud said:

Can someone say why we should be looking for level response up to 125mHz, or am I reading the scale wrong?

Because that's where the differences are.

[tmtomh]

18 minutes ago, mansr said:

That's largely down to impedance mismatches. The long Maplin has an impedance of about 75 Ω whereas the AFG and spectrum analyser are 50 Ω. This results in reflections which cause varying amounts of cancellation. An RG-59 coax looks similar.

 

So then would all the cables' responses look different when used in an actual analogue audio interconnect situation?

[manisandher]

On 1/6/2019 at 5:06 PM, manisandher said:

I'd say:

 

6 = RG-58 coax, 0.5 m

3 = RG-58 coax, 2 m

1 = Maplin Pro dual RCA, 0.75 m

 

2 hours ago, mansr said:

I think we've waited long enough. Here's the list:

1. Maplin Pro dual RCA, 0.75 m, 5.9 mm, black + black/grey braid
2. iFi branded dual RCA, 0.5 m, 3.7 mm, purple
3. RG-58 coax, 2 m, 4.8 mm, black
4. No-name not-quite-as-cheap dual RCA, 10 m, 2.8 mm, black with red/white plugs
5. Maplin Pro dual RCA, 3 m, 5.9 mm, black + black/grey braid
6. RG-58 coax, 0.5 m, 4.8 mm outer diameter, black
7. No-name video (yellow plugs) single RCA, 1 m, 2.8 mm, black
8. AudioQuest Tower dual RCA, 1 m, 4.7 mm, black with grey stripes
9. 21 AWG zip cord, 13 m, 2.0 mm, black
10. Maplin (non-pro) single RCA, 1.5 m, 3.7 mm, black with black/blue plugs
11. No-name cheap-looking single RCA, 5 m, 2.6 mm, black

 

Yipee... 3/3! (Although the Maplin was a total guess.)

 

FWIW, I use coax for my ICs.

 

Mani.

[Richard Dale]

47 minutes ago, Jud said:

Can someone say why we should be looking for level response up to 125mHz, or am I reading the scale wrong?

You may have spotted the nature of the troll.

[d_elm]

57 minutes ago, Jud said:

Can someone say why we should be looking for level response up to 125mHz, or am I reading the scale wrong?

Could it be for 10MHz square waves for clock signals ?  Nothing in analog audio above 100KHz to care about.

[mansr]

5 minutes ago, tmtomh said:

So then would all the cables' responses look different when used in an actual analogue audio interconnect situation?

Without impedance matched inputs and outputs, you'll always get some reflections. That's only a (potential) problem if the cable length is a significant fraction of the signal wavelength. The wavelength of a 100 kHz signal in a typical cable is 2 km. If you're wiring up a stadium, you should perhaps care. At home, it makes no difference at all.

[The_K-Man]

39 minutes ago, mansr said:

Because that's where the differences are.

 

Yeah, differences up where even dogs nor bats can hear!  sheesh...