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Post by lorriman on Oct 7, 2011 19:33:04 GMT
Rather than using the filter you can also equalise if you have a parametric equaliser. Any rockboxed device has one for those who don't know (ie. you can rockbox the clip+ and ipod and a variety of others). It's a but of a process to find the equalisations; you can read about it here: www.head-fi.org/t/413900/how-to-equalize-your-headphones-a-tutorial I've found several distinct spikes in the higher frequencies. I've also found that even when these are flattened out you still need about -7db's of treble adjustment using the tone controls. After that it compares quite well with my ety HF5's of neutral/flat fame (though considered on the bright side) but with much better bass. The parametric adjustments are : - |
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Post by lorriman on Oct 7, 2011 19:38:23 GMT
whoops, don't know what I pressed there. Here they are:
-2db 3400Hz q=0.6
-8db 5000Hz q=0.6 (probably due to ear canal resonance: so your ears may be different and you may find a higher q, ie. 1, helpful)
-3db 8400Hz q=1.3
-6db 12400Hz q=0.75
Also, as I mentioned, -7db on the treble tone control.
If you have the time it's worth doing this for yourself. Differences in ears and also in sample may require different equalisations. These where done after 2 days of pink noise.
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Post by lorriman on Oct 7, 2011 19:47:45 GMT
I should mention that I can't hear anything above 15000Hz so these equalisations may not be enough for younger ears.
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Post by renno61 on Oct 15, 2011 18:26:52 GMT
new to the site all i can say its fantastic
my question is i am also gonna change the cable to van damme starquad ,the hd 681 cable are black ,red and white.
is this right black=ground
red=left
white=right
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Post by renno61 on Oct 16, 2011 18:27:16 GMT
sorted it myself
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Post by davefo on Oct 16, 2011 22:41:49 GMT
Has anyone tried the HD681 on a CMoy? All I can say is, give it a go! Wow! Yes I have on a two home made cmoybb kits. I havent moded with filter yet, only changed the cable so far. Certainly the bassboost seams to help reduce the treble SSs |
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Post by davefo on Oct 17, 2011 0:35:04 GMT
Modifications carried out so far: Frans Filter externally mounted Cable replaced with Van Damme quattro michrophone cable Internal wiring renewed 2 pence pieces added Fish filter wool added to rear chamber Velcro sticky pad to rear of speakers. Velour ear pads Still to do: Aluminium ring set (get well Heliharris) Leather head pad. Very pleased with the improvements though the filter wool needs some trial and error to get it right. I used filter pads and cut them into the shape of a Polo mint. At first I lost the bass but by gradual reduction of the thickness found that about 8mm was enough. I still experience slight bass loss but everything is crisper and more accurate I think. Looking forward to receiving the Indeed G2 and comparing it to my Beresford dac.  What do you mean by filter pads? would this be like the filter material used in some kitchen hob extractors? I have a bit of that. would it be the correct material to use? |
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Post by lorriman on Oct 17, 2011 23:51:44 GMT
A practical rockbox parametric equalization needs an adjustment to the values I gave above. Rockbox only has 3 normal parametric equalizations and then two shelved. The shelves aren't appropriate to removing the spikes. For example you might be tempted to put the 12400Hz setting on the high shelf. But that'll attenuate not just the 12400Hz spike but everything higher also and by a whole 6db which is significant. So it's probably best to sacrifice the 3400Hz setting as it's only 3 db and then shift the settings to get the 12400Hz setting on to one of the normal equalisations. I didn't notice any special sibiliance after doing this, ie with female vocals. Peculiarly I found that I only needed -3 to -4 of treble reduction (on the treble control) after this change, rather than -7 to -10.
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Post by davefo on Oct 23, 2011 18:34:07 GMT
I've added 2 pences, fish tank filter wool, cable replacement and the filter mod to my hp's but drums sounds especially still appear to be very dominant, especially cymbals. For my filter I had to use parts from Maplins: www.maplin.co.uk/r.f.-chokes-3660 & www.maplin.co.uk/tantalum-bead-capacitors-394Does this mean that the filter is not working as intended or do i need to change the resistor values to increase the amount of filtering? How can I check that the filter is working properly? |
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Post by Deleted on Oct 23, 2011 18:45:58 GMT
Tantalums can ONLY be used with DC on them (in power supply or timer circuits)
They are semiconductor based and act like diodes and simply become defective (mostly shorted) when used without DC on it or when they have had reversed polarity voltages on it.
They need to be ceramic multilayer, bipolar aluminum electrolytic or other non-polar caps.
The inductor needs to be 470 uH and the DC resistance should be lower than 2.5 Ohm
The 470uH version of 470 uH is 8 Ohm. a bit too high but might not be the deal breaker.
The tantalum most likely is.
If the right components are used one can easily tell by ear.
the brightness remains unaltered only the fatigue and sibilance and a tad of highs is removed.
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Post by davefo on Oct 24, 2011 20:43:27 GMT
Thanks for that Solderdude. I'll source better components and start again. I don't know enough about electronics but want to learn. My next build project I am looking to make is a cheapish headphone amp. I was considering trying to build a tube amp to see what the audio quality is like. I've already made a couple of cmoy using JDS pcb. Any suggestions for a cheapish 1st time tube amp would be appreciated.
I have found the muse tube amp on ebay cheap but would really like to buy a kit for self assembly
thanks again
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Post by PinkFloyd on Oct 24, 2011 22:15:18 GMT
Thanks for that Solderdude. I'll source better components and start again. I don't know enough about electronics but want to learn. My next build project I am looking to make is a cheapish headphone amp. I was considering trying to build a tube amp to see what the audio quality is like. I've already made a couple of cmoy using JDS pcb. Any suggestions for a cheapish 1st time tube amp would be appreciated. I have found the muse tube amp on ebay cheap but would really like to buy a kit for self assembly thanks again Hi Dave, The Project Sunrise is possibly the best DIY "starter" valve amp out there at the moment... easy to build, good price and superb sonics... Frans helped with the design so you can be guaranteed it's a good one with SUPERB build instructions. I certainly would not overlook it. |
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Post by davefo on Oct 25, 2011 18:29:50 GMT
Thanks Pinkfloyd, I'll have a look. I Presume it is in the forums?
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Post by davefo on Oct 29, 2011 19:50:48 GMT
Hi
Does anyone have any instructions for stretching the replacement velour ear pads.
I find that the hole is too small to enclose my ears and they become sore after a while.
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Post by proid on Nov 3, 2011 13:00:31 GMT
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Post by Deleted on Nov 3, 2011 15:01:31 GMT
Connect the HD668B filter to the HD681.
The HD668B filter should have about the same effect (even a bit more filtering than HD681) on the HD681.
If not check the values of the 470uH inductor and yellow ceramic cap.
Another thing is the small brown ceramic disc cap is 150 pF but should be 150 nF (a factor 1000 difference) and ceramic multilayer.
This, however should only affect the sound when an amp with high output resistance is used.
Directly out of a DAP this should not make a difference.
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Post by Zest on Nov 5, 2011 10:41:46 GMT
Hi all, Here's my cable mod, braided John's Silver wire+Palics 3.5mm plug+AKG pads:   I don't hear any improvements in soundstage or resolution, but the piercing highs almost disappeared. I noticed Teflon is quite sensitive to microphonics. |
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Post by davefo on Nov 13, 2011 20:23:52 GMT
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Post by Deleted on Nov 14, 2011 0:45:06 GMT
Dave, Considering all the joints the signal has already passed through, an extra connector really isn't going to make much of a difference. After all it seems to work fine on 668B's  Jeff |
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Post by Zest on Nov 14, 2011 15:17:45 GMT
I'd like the idea of using 3.5mm mono socket on each cup, like on the Fischer Audio FA-003.
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Post by davefo on Nov 14, 2011 20:38:01 GMT
Zest
Time to get out your soldering iron then...
Jeff
that was my thinking. Makes it easier to use any length cable as well then.
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Post by Deleted on Nov 14, 2011 21:29:45 GMT
I'd like the idea of using 3.5mm mono socket on each cup, like on the Fischer Audio FA-003. I hate having cables around my head/neck area and can't get on with dual entry phones, one of the first of my many Grado mods was to single them up   My loathing of cables has gotten so bad recently that I now use these a lot especially when I'm mobile  Even when I sit down for a long session at my main rig I spend ages getting the cable so that's its just the way I want it. Sad, I know  IMVHO, I don't think there's a huge amount to be gained by modding a single entry to dual entry but each to his own - it can't hurt. Jeff |
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Post by renno61 on Nov 14, 2011 23:43:53 GMT
 By renno61 at 2011-11-06 i have recabled the 681 with van damme cable, dont know if it my imagination but it seems to have helped the highs.was going to use a old nylon lace to cover cable but when testing seem to be very microphonic. Attachments:
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Post by Zest on Nov 15, 2011 10:30:42 GMT
I hate having cables around my head/neck area and can't get on with dual entry phones, one of the first of my many Grado mods was to single them up <snip> IMVHO, I don't think there's a huge amount to be gained by modding a single entry to dual entry but each to his own - it can't hurt. I'm not a dual entry maniac , I just wondered if it was right changing the cable for SQ improvements and let the signal pass through the rods. I forgot to mention I replaced the red plastic rings with copper gaskets. |
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Post by davefo on Nov 15, 2011 21:43:45 GMT
I really do not like the red trim on these hp, has anyone found a cheap solution?
I didn't rewire mine as duel entry either since i'd rather have the cable to one side only.
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