solderdude
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Post by solderdude on May 15, 2013 14:08:51 GMT
Having a measurement rig and the release of the new HD681-EVO made me revisit my trusty old HD681. The results of these efforts are found here: www.mediafire.com/view/?w6mbyhb46tmcvyysneak preview of what the new filter design does: the before and after (R channel only)
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Rabbit
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Post by Rabbit on May 15, 2013 16:47:07 GMT
Hi Frans, the jpg is very small so I can't tell - is that left and right with the colours or before and after. If it's left and right, the match is ... well ....... OK .... sorry - I just had a look at the article, so it looks as though it's improved a lot now you have a measuring rig!! Can you hear much difference between the old modded with filter and the new modded with new filter? I guess you got the postage down to zero and got yourself an Evo? See what I mean about the shiny finish? Not keen on that, but I do like the sound. I'm gagging to see how the top end measures on your rig in comparison to the old one.
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solderdude
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Post by solderdude on May 15, 2013 18:51:33 GMT
I am waiting for the production Ember to arrive from the states. When it does I think you might be shipping the Horizon + HD681-EVO to the Neverlands and receive an Ember and modified HD681-EVO back after a while.
Haven't ordered one yet.
The filter I use also has the bass lowered and the sonic differences are noticeable but not big. Your filter only lowers the amount of highs but the 15kHz peak isn't lowered that much. Since you have the HD681-B I decided not to include the bass filter in your filter. How does the filter you have work on the EVO ?
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Rabbit
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Post by Rabbit on May 15, 2013 19:09:12 GMT
Since you have the HD681-B I decided not to include the bass filter in your filter. How does the filter you have work on the EVO ? The filter seems less pronounced on the Evo to me Frans. I have no idea why that might be. I now have the 681b, the 681 and the Evo. I'm becoming a Superlux fanboy!!! ;D TBH, the T40 is fine as a closed headphone for me. The Evo is a bit of fun. It has this really entertaining sound and I feel quite guilty listening to it because; a) It's just too cheap!!! b) It's not flat, but I really like it. It's like eating too many chocolates.
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Post by covenant on May 15, 2013 20:33:38 GMT
Frans, have you measured the effect of the wondrous ring set of the fabled Heliharris?
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solderdude
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Post by solderdude on May 15, 2013 20:42:45 GMT
The rings are glued on and will not be removed. It's highly unlikely they will change the frequency plot simply because they are not connected to the driver themselves. Resonances in the plastic cups will not show up in measurements involving sound pressure as they will always be 'overshadowed' by the stimulus (the tone used to sweep).
Measurements can only say so much and FR only says something about how loud each tone is played and nothing about other aspects.
The problem with headphones is the amount of variables involved that ultimately end up in being soundpressure. After that acoustics and how the brain perceives those soundpressure variations are involved making everything complex.
Audio, the digital and analog plane, are just simple voltages (or currents) changing in amplitude over time. There is only 1 'element' namely voltage (or current) that determines the waveform. Easy to measure and all critical points to measure the aspects involved are known to man. There are no mysteries there although many like to believe there are and base their theories on analogies that are not applicable or drag in the fact mankind doesn't know much about a lot of things and thus EE's don't know everything either.
As soon as those voltages encounter a transducer things become immensly complicated as there is only a voltage changing amplitude in time and to produce movement you need energy (Wattage) and thus also current.
Difficulties in transducers are the impedance (resistance) which varies in most drivers and is frequency dependant. These are caused by mechanical interaction of the mebrane, coil, and air surrounding it. So the Electrical signal is changing it's 'energy form' and differs from the original electrical voltage a mechanical movement (and ultimately sound pressure waveform) at this point. Adding an output resistance only makes this change bigger. This changes are taken into account by the designers by the way.
Next hurdle is the conversion of that energy (current for inductive drivers, voltage for electrostatic/piezo drivers) into movement of the voicecoil and the transference of that movement to a membrane that is always fixed around the edges. This cause resonances, break-up (parts of the membrane not moving in the same direction). The third hurdle is the coupling between the mechanical movement and the surrounding air (in front AND in the back). next hurdle is acoustics and materials where the soundpressure waves bounce against and the possible resonances in those materials (reflection and or absorbtion) and how those reflections interact with the sound pressure that is already present. That whole 'plethora' of soundwaves enter the ear canal and from then on physical properties come into play and above all HOW the brain can 'separate' the mumbo jumbo of complex signals and how the brain is able to 'extract' information from this varying sound pressure that only has some relation to the original electrical signal that was applied. Experience, physical health, and possibly many other factors will determine the end result which will vary from person to person depending on acoustical and 'brain' things.
The rings therefore will not affect FR and the differences it could potentially bring are only in reflections/absorbtion/conduction of sound pressure and will be much smaller in amplitude than the SPL emitted from the driver and thus 'drown' in the signal.
CSD's might not be accurate enough to show things that are detectable by the ear but might not be revealed in the CSD because of the way it is created.
Looking for changes made by the rings are also smaller than differences one would get by even slightly moving the headphone (repositioning) on the test rig anyway. Doesn't mean there are no audible differences though.
For me they are valuable because of the greatly improved looks in any case and the fact they were made by Mick. I honestly can't say how it changes the sound as there is lots of time and actions involved changing them and audible memory is a funny thing as well so do not rely on audible memory or perceived differences this way.
anyway... I need to go back to work.
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Rabbit
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Post by Rabbit on May 16, 2013 20:44:30 GMT
Experience, physical health, and possibly many other factors will determine the end result which will vary from person to person depending on acoustical and 'brain' things.
The funny thing about 'experience' and headphones for me Frans, has been the fact that my brain compensates very quickly for deficiencies in headphones.
I'm able to identify what I feel are problems, but I can so easily switch them out and just accept the headphone for what it is. I wasn't the same when I was younger. I was much more uncompromising in those days.
Also, nowadays, I'm very much a 'headphone for applications' type of person. I tend to choose the headphone to suit where I'm wearing it and what distractions are around me. (amount of isolation)
The mood thing is SO true as well. I remember once going away and arrived at the hotel totally tired out. It was very late and I put on 'Wish You Were Here' through a Portapro at extremely low volume. I became totally engaged with it.
Next morning, I played the album again. The Ipod was at same volume/same headphone - I could barely make it out; the volume was so low, that it had become nothing!!!
So, I know that I can be easily fooled and also, extremely forgiving of faults in headphones.
I guess, the 'purist' of old has left ........
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Post by madmac on Oct 15, 2013 7:03:08 GMT
I was wondering what the effect is of the "penny mod" where there's weight added to the cups. I didn't really get that
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solderdude
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Post by solderdude on Oct 15, 2013 7:22:07 GMT
Opinions vary as much as they do about anything. Just for laughs (I thought Mike was kidding) I replicated it with an Irish Euro coin (nice harp on it) and could not tell the difference. I did slap Mick's (beautyfully machined) alu ringset and end caps on my HD681 and really enjoy the looks and feel of it. This, the joint effort in those days, with Claus (now Hoved-fi founder) and Christian (disappeared from the scene) making nice headbands for it, Mick with the nicely machined parts and the filter mod all turned my HD681 in a memorabelia that sounds good as well for a really good price. Those alu rings beat the red plastic rings (the HD681-B already has better looking grey rings on it though) on every aspect. The cable came from a Skytronics headphone and is less microphonic than the original cable.
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Post by chinook9 on Oct 20, 2013 15:09:05 GMT
After reading too much about the Superlux mods, I decided I've got to do it.
Found the HD681 for $25 including shipping so the first decision is whether to order a spare.
I'm not supremely confident that I understand enough about the difference in the various types of capacitors and inductors to order the correct items, but I believe you provided what I need in the guide and I'll take a shot.
Franz, would like to hear if there is anything in terms of quality or branding of components that you recommend but left out of the guide.
Also on side note,what is status of high current Ember? I shot Jeremy an e-mail but haven't heard back. Would also like to get PCB for T50RP filter but I expect I should get that from Jeremy.
Last but not least, would like to confirm that one of the outputs on the Sunrise II is 10 Ohms.
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solderdude
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Post by solderdude on Oct 20, 2013 15:37:13 GMT
I had several spares but in the end sold them (only kept one)
The pads are almost obligatory but You could try to find HD681-EVO velvet pads they are very similar in size, feel and quality.
If you mount the components in the headphone size becomes important and a small sized inductors and ceramic multilayer caps (X7R) will be fine. Resistors can be low power.
For external filters the capacitors could be X7R or C0G/NP0 (hard to get) and the inductors could be bigger sized.
hight current Ember trial gave problems after a while and he is looking in other directions. 2 regs in parallel also gave problems as they shut each other off.
If Jeremy doesn't have time to experiment I can also try something here but haven't got high-current tubes. The start-up current of tubes differs from the nominal current and I can not test the start-up here.
SR-II = 5 Ohm / 68 Ohm output R
Filter PCB (bare board) can be bought from Jeremy or from me directly. Jeremy also supplies assembled boards/completed filters for USA/Canada.
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Post by chinook9 on Oct 20, 2013 16:15:17 GMT
Franz, thank you for the rapid response.
Is the sound quality of the HD681EVO pads comparable to the K240 pads? I am not concerned about comfort, just sound quality. I have spare SRH-840 pads that I can use but I will spring for the K240 or an HD681EVO if it makes a significant difference to the SQ. EDIT: Just found I can get the Superlux velour pads for $15.
I looked around briefly for components and I shouldn't have any problem finding them. I will be making my winter move to Phoenix at the end of the month and I'm sure Jeremy can put me onto a component supplier down there if needed. I'll get the headphone filter PCB then also.
Sorry to hear of the problem with the high current Ember.
If you would like, I have a spare 6N6P (or two) that I can send you, just PM an address. Let me know if you need more than one.
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solderdude
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Post by solderdude on Oct 20, 2013 17:01:52 GMT
The SQ from the K240 velours pads and EVO velvet pads is the same (they also measure very similar). Both are equally comfortable and also equally 'squeeky' with glasses.
I will ask Superlux if they sell the velourpads separately. I know they sell the pleather ones separately.
For now a tube isn't needed. Will talk to Jeremy about this issue though. Thanks for the offer...
IMO the filtered HD681 is better than the filtered HD681-EVO. When ordering the EVO just for the pads make sure they sell you the newer version (with the pads), the early EVO camne without these pads.
You can always resell the EVO for a very small price and keep the velvet pads.
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Post by chinook9 on Oct 21, 2013 15:18:01 GMT
Franz:
I found the following at Mouser and I think they'l work with the exception of the resistors which I'm not sure:
Fixed Inductors 470uH 0.28A 2.5ohms
Metal Film Resistors - Through Hole 56Ohm 3/5W 50PPM
Metal Film Resistors - Through Hole 27Ohm 3/5W 50PPM
Multilayer Ceramic Capacitors MLCC - Leaded 0.68uF 100volts X7R +/-10%
Aluminum Electrolytic Capacitors - Leaded 47UF 25V SU BI-POLAR
If any of these don't look good, please advise and I'll look some more.
I appreciate your help.
Also, If you have Farnell part numbers I can look them up on Farnell and then search for the same item on Mouser.
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solderdude
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Post by solderdude on Oct 21, 2013 20:57:28 GMT
Can you post the Mouser catalog numbers ?
810-FK16X7R2A684K = O.K. 810-FK26X7R2A684K = O.K. 810-FK16X7R1H684K = O.K. for instance but I got a lot of hits.
667-ECE-A1EN470U = O.K.
871-B82144A2474J = O.K.
279-LR1F56R = O.K.
279-LR1F27R = O.K.
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