Cable quality versus internal wiring quality

[Chuck Dee]

The first and most obvious difference between internal and external wiring is the 'environmental conditions'.
The internal wiring will have been designed, developed and tested to work properly in supplying an optimal signal between the connector(s) and drivers. This will include consideration for EMI/RFI interference, distortion, resonance, capacitance, impedance and any potentially detrimental effects on the signal path.
Not all headphone manufacturers place the same importance or consideration on the internal wiring however so there will be variance for quality and implementation but most will have at least given minimal consideration during the design/development phase and I consider that this has only improved in general over the last 30 years.

My favourite 'Made in Ireland' era of Sennheiser headphones are testament to the fact that things were done, let's say, sub-optimally in the past, what with those micron-thin conductor wires running through a hollow channel in the driver/cell structure from the connectors to the voicecoils. I think the design has carried through to the current 660 drivers if I'm not mistaken. When those wires break accidentally or otherwise there's NO repairing them. Go near them with a soldering iron and they just evaporate! I recall Tyl Hertsens trying and failing to repair one of these wires and it's also documented here.

External cables DO make a difference whether you believe they do or not and I'm also not really interested in getting into a debate about it. All I'll say though is that new signal-characteristics such as 'timing' and 'propagation' are being discovered, measured, analysed and demonstrated to make audible differences.
Alpha Audio here in NL recently conducted some interesting analysis on various cables here.
Far from conclusive but interesting nonetheless and certainly warrants further investigation in my view.

Microphonics-damping and EMI/RFI-mitigation should be minimum characteristics of all headphone cables and I'm constantly amazed at the poor quality proprietary cables supplied with some TOTL headphones! Looking at you Meze and Hifiman!

 

[2leftears]

It is a bit of an impractical extension of the logic of this discussion but it (sort of) surprises me that somebody hasn't put forward the notion that they can hear connections, adapters, cables, solder types, point to point wiring etc to the extent that they mess with hard wiring the headphone cable directly to the (point to point wired) amplifier internal outputs and to the drivers, wouldn't that be the best case scenario ?

Perhaps not quite as impractical as you might think; because by that stage you are getting close to an active headphone really, which does exist; any headphone with a built-in amp like noise cancelling and BT ones.

Sounds ridiculous to suggest that but frankly no less so than other ideas put forward by folks - saw one recently where the guy said he could clearly tell the difference with the direction of a USB cable, why would one even think to try that out ? actually even said his young grandchild could easily hear it .... yes after you told her to listen for something .... the power of psychology seems to be genuinely lost on so many people it is ridiculous.

Re. the direction of the USB cable, some RCA interconnects are marketed to have directionality. In fact the marketing of audible directionality of cable(s) has been around for a while; I remember that being discussed back in the 80's but it likely predates even that. Regardless of whether you believe in audible cable directionality or not (I don't), it is highly likely that some manufacturers will simply have printed an arrow on a standard cable and then charge a hefty premium.

 

[2leftears]

The first and most obvious difference between internal and external wiring is the 'environmental conditions'.
The internal wiring will have been designed, developed and tested to work properly in supplying an optimal signal between the connector(s) and drivers. This will include consideration for EMI/RFI interference, distortion, resonance, capacitance, impedance and any potentially detrimental effects on the signal path.

Indeed (you left out inductance). And judging from the innards of the vast majority of audio equipment the manufacturers' conclusion invariably seems to be that thin unshielded PCB signal traces not too close to the PSU, cheap industry-standard equipment wire, ribbon cables, and connectors are perfectly adequate. Problems with external environmental conditions are rarely (if ever) solved by using more expensive conductor materials or space-age insulators, rather a change in connection topology may be called for (e.g. unbalanced->balanced).

My favourite 'Made in Ireland' era of Sennheiser headphones are testament to the fact that things were done, let's say, sub-optimally in the past, what with those micron-thin conductor wires running through a hollow channel in the driver/cell structure from the connectors to the voicecoils. I think the design has carried through to the current 660 drivers if I'm not mistaken. When those wires break accidentally or otherwise there's NO repairing them. Go near them with a soldering iron and they just evaporate! I recall Tyl Hertsens trying and failing to repair one of these wires and it's also documented here.

That is irrelevant to the discussion here. The reason Sennheiser chose that methodology is that on earlier models those ultra-thin wires are made of aluminium, not copper; you can't solder to them so the most effective way to keep the voice coil lightweight was to lead out the voice coil wire and crimp-terminate it into the cable contacts. Is it ideal? -no; could it be done differently? - yes, but it is a perfectly adequate solution unless you open up the capsules and don't take care not to damage those wires.

External cables DO make a difference whether you believe they do or not and I'm also not really interested in getting into a debate about it. All I'll say though is that new signal-characteristics such as 'timing' and 'propagation' are being discovered, measured, analysed and demonstrated to make audible differences.
Alpha Audio here in NL recently conducted some interesting analysis on various cables here.
Far from conclusive but interesting nonetheless and certainly warrants further investigation in my view.

Such research would need to be conducted with a big enough sample size of test subjects to be statistically significant, and to an academic standard by researchers not affiliated with audio manufacturing/sales.

 

[Chuck Dee]

That is irrelevant to the discussion here. The reason Sennheiser chose that methodology is that on earlier models those ultra-thin wires are made of aluminium, not copper; you can't solder to them so the most effective way to keep the voice coil lightweight was to lead out the voice coil wire and crimp-terminate it into the cable contacts. Is it ideal? -no; could it be done differently? - yes, but it is a perfectly adequate solution unless you open up the capsules and don't take care not to damage those wires.

I would suggest it's highly relevant to the discussion here seeing as how Sennheiser use exactly the same design in their current drivers.
Those wires fail and are susceptible to failure via drops/knocks. Ask me how I know. I have approx 38/39 refurbed-by-me sets using this driver design up to the current HD660 model. I have boxes of drivers where the connector springs and/or wires have failed. The wires are soldered and not crimped as you claim. (see photo)
My 30 years in product development makes it clear to me at least that this 'perfectly adequate solution' as you term it is actually nothing but a cost-driven design compromise.

 

[XTF1]

I would suggest it's highly relevant to the discussion here seeing as how Sennheiser use exactly the same design in their current drivers.

My 30 years in product development makes it clear to me at least that this 'perfectly adequate solution' as you term it is actually nothing but a cost-driven design compromise.

So the relevance to the discussion is that nobody should ever buy an upgrade cable for a Sennheiser headphones, correct?

 

[2leftears]

I would suggest it's highly relevant to the discussion here seeing as how Sennheiser use exactly the same design in their current drivers.
Those wires fail and are susceptible to failure via drops/knocks. Ask me how I know. I have approx 38/39 refurbed-by-me sets using this driver design up to the current HD660 model. I have boxes of drivers where the connector springs and/or wires have failed. The wires are soldered and not crimped as you claim. (see photo)
My 30 years in product development makes it clear to me at least that this 'perfectly adequate solution' as you term it is actually nothing but a cost-driven design compromise.

I was talking about the drivers you showed in your first photo in your previous post, which is an older style with non-copper-clad aluminium wires which are definitely not soldered but crimped. You cannot solder aluminium to copper without the use of an extremely aggressive flux and a high solder temperature which that thin wire simply wouldn't survive. On the original photo you showed you can see the little tubes they dive into, the bottom of which they are crimped in. I refurbish Sennheisers too, and all the 250/540/560 models I serviced had crimped wires, not soldered. On these later drivers you showed above it looks like they use different contact spring design and they are a different matter entirely; if those voice coils are still aluminium wire it will be either copper-clad aluminium or a copper-aluminium alloy wire seeing they look indeed soldered on those later headphones.

I have no experience with the later Sennheisers, but the multiple HD 540/250/560/650 units I have have never broken, nor have I come across much in the way of complaints that those models were liable to get those wires broken, unless folks opened them up to do DIY mods. If they were really such damage-prone don't you think after 40(!) years of using this wire connection style they would have changed it?

 

[2leftears]

So the relevance to the discussion is that nobody should ever buy an upgrade cable for a Sennheiser headphones, correct?

No, the cables are a different matter; the disagreement above is about the termination of the voice coil wire to the spring contacts; the headphone cable simply clips into those spring contacts...

Sennheiser headphone cables have had their issues over the years, and the spring contacts shown aren't designed to cope with too many cable changes, but that's a different topic.

 

[XTF1]

No, the cables are a different matter.

If Sennheiser internal wires are a cost-driven (bad) compromise, what’s the point of investing in high-end external cables?
Based on what you described, any external cable would be at a minimum of the same quality as the Sennheiser internal wires…

 

[2leftears]

If Sennheiser internal wires are a cost-driven (bad) compromise, what’s the point of investing in high-end external cables?
Based on what you described, any external cable would be at a minimum of the same quality as the Sennheiser internal wires…

Confusing, isn't it? But you need to separate form and function, and compare like with like in terms of what the purpose of any bit of cabling/wiring actually is.

First, these internal wires in the Sennheiser capsules are not a cost-driven bad compromise at all. It is an aluminium wire chosen for its low mass, in order to keep the voice coil as light as possible.
Second, that aluminium wire serves a different purpose: its main purpose isn't to provide a low resistance galvanic connection between two distant points, rather its main purpose is to channel a high current density right into the magnetic field contained in the gap of the field magnet, at as low a mass density as feasible.

But at some level you are right; those early Sennheiser models consequently had high 600 Ohm (later 300 Ohm) voice coil impedances, and indeed fretting about high-end external cables becomes a complete non-issue, because these high-impedance cans' sound signature is far less sensitive to the quality of the cable used. A high impedance voice coil may sound like a problem, but it has a few advantages. Whilst high impedance cans are more difficult to drive in terms of needing a higher amp voltage, they are easier to drive in terms of requiring a lower current, and as I already said they are far less sensitive to differences in amp output impedance and cable resistance. In fact the early models came with a steel (not copper) detachable headphone cable that sounded just fine with those cans to my ears. I later switched to copper cables because of the awkward mechanical properties of the steel cable, but I didn't notice any improvement in the sound. I have tried a few different cables and on those high impedance Sennheiser cans I found them all to sound the same (i.e. all excellent), which is precisely what you would expect when connecting any half-decent low resistance cable to a high impedance voice coil. Some claim that other cables sound better on these cans, but those claims would need to be properly tested before I gave them much credence.

 

[XTF1]

Confusing, isn't it? But you need to separate form and function, and compare like with like in terms of what the purpose of any bit of cabling/wiring actually is.

First, these internal wires in the Sennheiser capsules are not a cost-driven bad compromise at all. It is an aluminium wire chosen for its low mass, in order to keep the voice coil as light as possible.
Second, that aluminium wire serves a different purpose: its main purpose isn't to provide a low resistance galvanic connection between two distant points, rather its main purpose is to channel a high current density right into the magnetic field contained in the gap of the field magnet, at as low a mass density as feasible.

But at some level you are right; those early Sennheiser models consequently had high 600 Ohm (later 300 Ohm) voice coil impedances, and indeed fretting about high-end external cables becomes a complete non-issue, because these high-impedance cans' sound signature is far less sensitive to the quality of the cable used. A high impedance voice coil may sound like a problem, but it has a few advantages. Whilst high impedance cans are more difficult to drive in terms of needing a higher amp voltage, they are easier to drive in terms of requiring a lower current, and as I already said they are far less sensitive to differences in amp output impedance and cable resistance. In fact the early models came with a steel (not copper) detachable headphone cable that sounded just fine with those cans to my ears. I later switched to copper cables because of the awkward mechanical properties of the steel cable, but I didn't notice any improvement in the sound. I have tried a few different cables and on those high impedance Sennheiser cans I found them all to sound the same (i.e. all excellent), which is precisely what you would expect when connecting any half-decent low resistance cable to a high impedance voice coil. Some claim that other cables sound better on these cans, but those claims would need to be properly tested before I gave them much credence.

I think I mixed some of @Chuck Dee comments with yours—apologies for that.

I understand the tradeoffs relative to the voice coil cables. But if Sennheiser chose to expand the voice coil links 1 or 2” beyond the driver itself per the above pictures, doesn’t it become the “weakest link”?

 

[bagwell359]

The internal wiring will have been designed, developed and tested to work properly in supplying an optimal signal between the connector(s) and drivers. This will include consideration for EMI/RFI interference, distortion, resonance, capacitance, impedance and any potentially detrimental effects on the signal path.
Not all headphone manufacturers place the same importance or consideration on the internal wiring however so there will be variance for quality and implementation but most will have at least given minimal consideration during the design/development phase and I consider that this has only improved in general over the last 30 years.

Thats a lot more credit than I give most manufacturers. HFM does great work with many of its drivers, but the rest of the cans appears focused on cutting costs and shows very little to no consideration of sonics or longevity. The HEX v2 is an example, the internal cable is long and probably 28 or higher (meaning very small ga). It was longer than needed, it was pinched by the cups in places and it could have been much more robust at essentially no weight increase.

 

[2leftears]

I think I mixed some of @Chuck Dee comments with yours—apologies for that.

I understand the tradeoffs relative to the voice coil cables. But if Sennheiser chose to expand the voice coil links 1 or 2” beyond the driver itself per the above pictures, doesn’t it become the “weakest link”?

Those are macro images; in reality it is no more that 3/4 of an inch or so. There is nothing wrong with an aluminium conductor for audio signals; if there was then those early Sennheiser headphones would not have the good reputation that they do, because those voice coils contain several yards of really thin alumimium wire. Those 3/4 inch little bits extra are not going to make any difference, although in theory they could indeed have terminated them right at the edge of the driver diaphragm.

So in theory you might call it the weakest link, but in practice those very small lengths of wire extending beyond the driver are a complete red herring; there are far bigger compromises involved in the actual voice coil design which are trade-offs between voice coil mass, impedance, and e.g. the choice of how to linearise the driver which is a combination of diaphragm compliance linearity as well as whether or not (and by how much) to overhang/underhang the voice coil beyond the maximum field flux in the magnetic gap, which in turn depends on whether the gap has a saturated field or not and therefore the magnetic field geometry, etc. etc.

Anyone interested in those sort of details I can recommend "Loudspeaker and Headphone Handbook", Third Edition, John Borwick, Focal Press, 2001. This is a very useful compilation of all manner of speaker design and construction science and theory, and contains a section about aluminium voice coil pros/cons and considerations.