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Post by Koolind on Mar 4, 2010 21:24:15 GMT
Haven't found the time to experiment with dampening yet. I've built a filter by Frans' recipe and just enjoyed the music since. HD681 sound significantly better now (after 150+ hrs) and a lot more balanced. Prior to dampening the cups I plan to rewire them (dual entry) I have a question to ask (perhaps a bit silly): What is the part name for the cable splitter in the photo?  I cannot find anything at Farnell. Every "cable splitter" search gives me connectors, adapters and such. Is there a special name for it? Where can I get such a thing? I've cropped the last picture Lars posted here, for exemplification (hope Lars doesn't mind) I hope it is allright that I reply for him, the splitter was one he butchered from a pair of Sony sa5000 if I recall correct.. That is exactly what it is. I have earlier recabled my Sony SA5000's and stole the splitter from that cable. So i am sorry to say that i cant really help you find one. However i must say that this fits quite good in size with the cables and such ;D |
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Post by Deleted on Mar 4, 2010 22:34:08 GMT
I have a question to ask (perhaps a bit silly): What is the part name for the cable splitter in the photo? I cannot find anything at Farnell. Every "cable splitter" search gives me connectors, adapters and such. Is there a special name for it? Where can I get such a thing? Hi Bogdan, As someone once said to me on a forum, the only silly question is the one you don't ask. Instead of going the way of the photograph, why don't you go the way I went. I fed both earpieces with one of these, which have seperate cables all the way from the jack plug: - www.maplin.co.uk/Module.aspx?ModuleNo=35898They are made by Nikkai under the lable of Pure Connectivity. I cut off the female phone plugs and soldered each seperate lead to seperate ear piece drivers. The SQ was very good, IMHO, and certainly better than the original. I think these cables go well with the 681s. Hope this helps, Dave. |
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insomniac
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Post by insomniac on Mar 4, 2010 23:03:02 GMT
Neat idea Dave.... I like it!  |
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Post by PinkFloyd on Mar 4, 2010 23:16:53 GMT
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Post by Deleted on Mar 4, 2010 23:44:14 GMT
Ah but, ..... my method is much easier for the novice DIYer, and cheaper too. Dave. |
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Post by oink1 on Mar 5, 2010 3:18:12 GMT
Anyone heard the 681B or 681F???
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Post by JohnnyBlue on Mar 5, 2010 7:01:06 GMT
I'd wondered about this after reading a similar suggestion (albeit less detailed) earlier in this thread: are there no consequences to the lack of screening from the Y-junction split to the headphones? |
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Post by covenant on Mar 5, 2010 7:36:10 GMT
The sound absorbing treatment that Koolind has done looks easy and cost effective. The only thing is it makes you wonder why the manufacturer doesn't do something similar. I know they are cheap cans but you must be talking pennies on a mass production scale. Do the expensive headphones have similar treatment?
By the way Koolind, that looks a nice jack plug you have fitted-where did you get it?
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Post by PinkFloyd on Mar 5, 2010 7:37:53 GMT
I'd wondered about this after reading a similar suggestion (albeit less detailed) earlier in this thread: are there no consequences to the lack of screening from the Y-junction split to the headphones? No Johnny, The twisted pairs ensure the cable is screened  |
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Post by JohnnyBlue on Mar 5, 2010 8:00:26 GMT
I'd wondered about this after reading a similar suggestion (albeit less detailed) earlier in this thread: are there no consequences to the lack of screening from the Y-junction split to the headphones? No Johnny, The twisted pairs ensure the cable is screened Really? I'd always assumed screening had to be a physical screen, i.e., wrapped around the conductor(s). Then we get into the world of number of twists per metre (or foot in real money)! |
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Post by Deleted on Mar 5, 2010 9:34:58 GMT
HP's and speakers do not NEED any screening (from a technical point of view ;D) It is an un-balanced system with low ohmic and relatively high voltages. twisting pairs help in BALANCED circuits as the pickup of COMMON mode signals is equal in both wires. HP's and speakers are unbalanced and very unsensitive to pickup of outside signals (low Ohmic) At high freq. (1MHz and up) and instable amps with low-ohmic outputs there can be adverse effects though.  Symmetrical HA's with 4 wires are balanced and because of this you SHOULD use UNSCREENED wires ONLY, if you DO use screened cable in this particular case you are loading the output of the amp unsymmetrically and this is exactly what you don't want to do  Twisting the wires can be helpfull in this case for reasons mentioned above. Of coarse this is ONLY from a technical point of view and in the audioworld physics rules do not (seem to ?) apply sometimes, or only partially If you perceive a specific cable to be better as another than go with the flow and have a field day. |
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jkeny
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Post by jkeny on Mar 5, 2010 12:31:44 GMT
I would mostly agree with Frans, & would add this, that balanced benefits are only really realised by using a balanced amplifier too. I'm not sure I understand what he says about Symmetrical HA's (is this the same as a balanced HA?) - are these not designed to have a hot/cold & ground connections for each channel?
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Post by Deleted on Mar 5, 2010 12:44:08 GMT
symmetrical = balanced...  the hot/cold can better be referred to as +/- in this regard that it does not apply to voltages referenced to ground but to the phase difference between the 2 wires (phase of the signals is opposite from each other where the + side has a NON inverted signal with respect to ground (would be the same signal as a normal signal when referenced to ground or common signal as is used in most HA's) The ground connection on a balanced system is usually tied only to the screen and housings. In some cases it is connected to the exact middle of a coil (centre contact CT). HP voicecoils in general do NOT have centre contacts. There is ton's on info on balanced/unbalanced signals on the web. Wiki it ..  en.wikipedia.org/wiki/Balanced_audio |
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jkeny
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Post by jkeny on Mar 5, 2010 12:50:26 GMT
Yes, Frans, that's what I thought but why then would the screen not be connected to ground? - how would this be asymmetric for the amp? I'm not challenging you, I just need to learn.
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Post by Deleted on Mar 5, 2010 13:11:16 GMT
You can connect the screen to ground IF you have 2 wires AND a screen going to each driver.
The screen you will have to connect to the ground of the HA.
The 2 wires on the +/- output.
On the receiving side (i.e. the headphone driver) you ONLY connect the 2 wires and leave the screen unconnected (do not connect it to one of the wires it only acts as a 'safety ground')
using 1 center wire and 1 screen wire totally defeats the whole purpose/advantage of symmetrical/balanced amps.
The only advantage you will be having is 6dB extra power in this case.
For balanced = symmetrical = differential mode driving you do NOT need screened wires.
a twisted pair will do and has lower capacitance than if a screen were used.
The screen does NOT carry any current/signals and is normally intended for blocking common mode injected signals (be it capacitive or inductive coupling) affecting the (NOT common mode) audio signals and should be connected to ground on both sides of the wire to be really effective at this.
When driving balanced the screen is only useful in electrically noisy environments AND very low level signals (microphones, sensors, cartridges) as a balanced signal on itself already is quite insensitive to common mode signals.
Common mode signals are signals induced in wires from the outside OR when 2 wires carry the exact same voltage.
Common mode signals present in the 2 wires cancel each other OUT and therefore have no influence.
Twisting the wires ensures that if these wires go though a 'interfering' signal the signals in both wires will be equal.
If they are NOT twisted 1 of the wires may pick up more voltage than the other one resulting in an unwanted signal on top of the original signal.
Not common mode (single ended = normal audio signals (RCA, Tulip, HP) signals carry a signal that is referenced to a ground (or common) wire and in this case if there is inductance/coupling in the signal wire it is 100% added to the audio signal.
a screen connected to ground will 'block' the interfering signal from reaching the audio carrying signal.
The screen will have to be as low ohmic as possible.
<edited ;D>
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robertkd
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Post by robertkd on Mar 5, 2010 13:23:28 GMT
Yes, Frans, that's what I thought but why then would the screen not be connected to ground? - how would this be asymmetric for the amp? I'm not challenging you, I just need to learn. It would, balanced systems for studio and professional audio are screened, phone lines are not! The screen provides an electrostatic shield to the signal carrying pair and as such does not carry any signal information, any loading of the differential "balanced" drive is in the form of capacitance from the signal wires to ground, capacitance between the two conductors in the pair as well as capacitance to ground. I have posted before on this, my personal view is that balanced provides no real benefit for headphones, as Frans says anyone feels it somehow improves sound for anyone that is good, but in reality you have double the electronics in the signal path therefore double the distortion and noise introduced by the additional electronics, it's pretty simple. Yes I agree that with modern designs these figures distortion and noise figures are low, and in interconnecting equipment balanced inherently has advantages for relative immunity to common mode noise induced into cables as well as benefits for reducing effects of hum loops, but we are considering different signal levels and impedances! I wouldn't use anything else but balanced for microphones, or even balanced line level between mixers and A to D's or even balanced form mixers to active speakers, but they are systems designed to be used that way and the trade off's usually (most always!) out weigh the disadvantages. my two bobs worth,... |
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robertkd
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Post by robertkd on Mar 5, 2010 13:28:48 GMT
You can connect the screen to ground IF you have 2 wires AND a screen going to each driver. The screen you will have to connect to the ground of the HA. The 2 wires on the +/- output. On the receiving side (i.e. the headphone driver) you ONLY connect the 2 wires and leave the screen unconnected (do not connect it to one of the wires) using 1 centre wire and 1 screen wire totally defeats the whole purpose/advantage of symmetrical/balanced amps. The only advantage you will be having is 6dB extra power in this case. For balanced driving you do NOT need screened wires. a twisted pair will do and has lower capacitance than if a screen were used. The screen does NOT carry any current/signals and is normally intended for blocking common mode injected signals (be it capacitive or inductive coupling) affecting the (NOT common mode) audio signals and should be connected to ground on both sides of the wire to be really effective at this. When driving balanced the screen is only usefull in electrically noisy environments AND very low level signals (microphones, sensors, cartridges) as a balanced signal on itself already is quite insensitive to common mode signals. Common mode signals = signals induced in wires from the outside OR when 2 wires carry the exact same voltage. Common mode signals present in the 2 wires cancel each other OUT and therefore have no influence. Twisting the wires ensures that if these wires go though a 'interfering' signal the signals in both wires will be equal. If they are NOT twisted 1 of the wires may pick up more voltage than the other one resulting in an unwanted signal on top of the original signal. Not common mode (differential mode = normal audiosignals (RCA, Tulip, HP) signals carry a signal that is referenced to a ground (or common) wire and in this case if there is inductance/coupling in the signal wire it is 100% added to the audiosignal. a screen connected to ground will 'block' the interfering signal from reaching the audiocarrying signal. The screen will have to be as low ohmic as possible. Umm no Frans differential is balanced, RCA etc is unbalanced or single ended  Most headphone balanced systems usually connect a screen to the earth on the source only therefore only provides an electrostatic screen to the balanced signal, or no screen at all. Robert |
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Post by Deleted on Mar 5, 2010 14:07:57 GMT
Oops .. have been goofing... 'differential' now replaced by 'single ended' thanks for the correction... it proves that people bother reading my essays. ;D |
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robertkd
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Post by robertkd on Mar 5, 2010 14:36:04 GMT
Oh absolutely Frans, BTY luv your work and it's great to see you back on PS What is with the "post reply" button, no matter how many times I proof read, the errors don't show till I post the reply,... is it just me Robert |
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Post by clausdk on Mar 5, 2010 14:59:36 GMT
You can connect the screen to ground IF you have 2 wires AND a screen going to each driver. The screen you will have to connect to the ground of the HA. The 2 wires on the +/- output. On the receiving side (i.e. the headphone driver) you ONLY connect the 2 wires and leave the screen unconnected (do not connect it to one of the wires) using 1 centre wire and 1 screen wire totally defeats the whole purpose/advantage of symmetrical/balanced amps. The only advantage you will be having is 6dB extra power in this case. For balanced driving you do NOT need screened wires. a twisted pair will do and has lower capacitance than if a screen were used. The screen does NOT carry any current/signals and is normally intended for blocking common mode injected signals (be it capacitive or inductive coupling) affecting the (NOT common mode) audio signals and should be connected to ground on both sides of the wire to be really effective at this. When driving balanced the screen is only usefull in electrically noisy environments AND very low level signals (microphones, sensors, cartridges) as a balanced signal on itself already is quite insensitive to common mode signals. Common mode signals = signals induced in wires from the outside OR when 2 wires carry the exact same voltage. Common mode signals present in the 2 wires cancel each other OUT and therefore have no influence. Twisting the wires ensures that if these wires go though a 'interfering' signal the signals in both wires will be equal. If they are NOT twisted 1 of the wires may pick up more voltage than the other one resulting in an unwanted signal on top of the original signal. Not common mode (single ended = normal audiosignals (RCA, Tulip, HP) signals carry a signal that is referenced to a ground (or common) wire and in this case if there is inductance/coupling in the signal wire it is 100% added to the audiosignal. a screen connected to ground will 'block' the interfering signal from reaching the audiocarrying signal. The screen will have to be as low ohmic as possible. <edited ;D> I feel dizzy  |
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Post by Deleted on Mar 5, 2010 15:38:36 GMT
And I thought I'd clarified things instead of making people feel dizzy. it all boils down to: 1: balanced headphones need 4 wires in 2 pairs (twisted or not) 2: 'normal' headphones need at least 3 wires. these you can split into subcategories. 2a: 4 wires the 2 common wires connected to the common (Ground) in the plug that goes into the HA (the common wires being a screen, has low resistance) dual entry topology  2b: 4 wires the 2 'common' wires connected to the common (Ground) into the split or in the plug that goes into the HA (the common wires being normal wires) dual entry topology 2c: 3 wires where the common wire consists of 1 (or 2) screens of screened wire. The screens provide a lower resistance as a normal wire would which is a good thing. single entry topology 2d: 3 wires (stock cable) where the common wire is just a wire. This wire carries the common current of BOTH drivers. No need to twist these wires. Common single entry topology don't worry about the rods being used as conductors .. Excellent conductors that do not need screening or twisting Far better than an equal length of wire. Aaahhhh the choices we have to make. ;D |
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Post by clausdk on Mar 5, 2010 16:03:55 GMT
And I thought I'd clarified things instead of making people feel dizzy. Well when I have read it 25 times or so, I will begin to understand,. But ones again for the slow people in the audiens ;D ;D If I recable a headphone, normal Jack four strands, I should chose a: a.) Unshielded cable ?? B.) Or a Shielded cable ?? |
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Post by Deleted on Mar 5, 2010 18:39:12 GMT
Shielded cable will have a lower resistance. You can't have enough of that in an HD681. So the preference would be: 'shielded'.. Not because it is shielded for the shield won't 'shield' anything as there is nothing to shield (low ohmic circuit, relatively high voltage) It's all about low ohmage in this case. Of coarse there is always 'the unknown' signal which nobody really knows anything about and plays a HUGE role in the conductance of sound (not electrical signals) but is greatly affected by dielectrics, copper purities, solder joints, connector materials, shoe-laces, plastics, isolators (can you tell which one doesn't belong ?)  Very open for debate and subject to personal taste and conviction. I can only answer on 'Technical' issues and my postings are only that... so if your can's sound much better with another cable and it can't be technically explained than just feel good about the investment and enjoy the sound of your modded HD681 even more. Is there a cable thread ? This really belongs in there. ;D |
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jkeny
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Post by jkeny on Mar 5, 2010 19:25:39 GMT
At the risk of boring everybody can I summarise to see if I understand & ask some further questions:
- An unscreened cable with 2 twisted pairs is what's needed for headphones & then only if driven from a balanced HA. A screened cable is only needed for low level signals, like microphone or line level.
Here's my question: - are there not also some low level signals on the headphone cable that would benefit from being screened?
I'm also not so sure about "double the electronics in the signal path therefore double the distortion and noise introduced by the additional electronics, it's pretty simple". Firstly, balanced operation cancels 2nd & 4th harmonics and can remove 99% of common noise that may be generated internally in some output stages! Noise isn't always from an external source!
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Post by clausdk on Mar 5, 2010 20:51:21 GMT
This is where it all goes haywire to me, if it has lower resistance, and we want as much resistance as possible, would the correct not be unshielded..
Ans I will not use the shield as ground
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