Rabbit
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Post by Rabbit on Aug 24, 2013 15:05:31 GMT
The control in the bass is quite surprising Frans. The flat version looks very good; especially given the cost of the headphone. Very surprising.
Ultimately, flat is how it ought to be rather than compensate for poor recordings. After all, that's what eq was made for I guess!!
Such a versatile headphone. I guess distortion isn't increased too much at flat?
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solderdude
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Post by solderdude on Aug 24, 2013 15:14:47 GMT
No increase in distortion.
Still have to look at the CSD ... it will most likely only improve.
I like it in 'flat' and as a bonus can be driven directly from portable gear. Not on par with ortho's but very good VFM. Also the 'fun' one is a good listen.
need to work on the article about it... Might also investigate what happens if I flatten the original HD681 even more. It lacks that 4kHz dip.
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Rabbit
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Post by Rabbit on Aug 24, 2013 15:26:59 GMT
SO many options Frans. Thing is with the nodded T40, an amp is a MUST on portable gear but this could be driven as is.
Not too much away from sensitivity either?
Fantastic work on this as well. It's much appreciated Frans.
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solderdude
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Post by solderdude on Aug 24, 2013 16:54:17 GMT
I take it you want the 'flat' one or with just slightly raised bass, say 1-2 dB ? Personally I think it sounds very good on good recordings (like the modded Fostexes do) but rather poor on average to bad recordings. For those planning to build the filter outside of the headphone one could use a 100 Ohm potmeter and 'adjust' the bass to your needs. The highs just need to be lowered slightly. Plays pretty loud directly out of my FiiO X3
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Rabbit
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Post by Rabbit on Aug 24, 2013 17:17:59 GMT
Perhaps a slightly raised bass Frans? Since I mostly use it moving around rather than at home, I'll be listening mostly to portable files. Mind you, I do like the T40. It's hard not having heard it but a touch of 'sugar' in the bass may sweeten any nasty files. Then again, I'm not sure. I like my 'flat' t40!! I should have sent two!!
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proid
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Post by proid on Aug 27, 2013 10:27:37 GMT
May be i'm too ambitious but Frans, can you tune the filter or install 2nd filter to further more lower the mid bass hump in the EVO even more to get very linear FR like this?
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solderdude
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Post by solderdude on Aug 27, 2013 11:36:21 GMT
That hump around 60Hz can only be lowered with mechanical damping (at least in my T50 adventures I was able to specifically target that area with damping) but will also affect the range up to 300Hz. From 100Hz to 700Hz it now runs very flat which would no longer be the case.
One has to keep in mind that the lowest bass notes are around 50 to 60Hz and most lows are between 60Hz and 100Hz in general . Oposite the part up to 800Hz the increase is just 3-4dB which gives it a nice deep bass without a hint of muddy sound which is lacted between 100 and 500Hz roughly.
I have been listening and tuning the filter by ear while comparing to other headphones.
When I am done I will measure what I came up with audibly. All I can say for now is it will be closer to the grey plot than the green one. Even with filter it isn't as good as my better headphones (filtered DT1350 and T50 as well as HD650) but sounds o LOT better than the stock EVO
I might do some experiments with damping once I have it opened up. perhaps less electronic filtering can be used when mechanical damping is applied.
The only 'problem' with mechanical damping is the amount and type of damping materials will have to be determined quite exactly to duplicate the effect. With all electronic filtering the amount of filtering and thus the effect will always be the same, which is a bonus if you want to get close to a similar result.
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proid
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Post by proid on Aug 27, 2013 12:44:14 GMT
I hope you will release the article soon because today, i just got the new EVO and out of the box, it sound terrible, too much bass, too muddy, the original 681 is much more clear, bass is tighter, faster, more control. I hope it will be better with a filter and i'm also burning it.
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solderdude
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Post by solderdude on Aug 27, 2013 13:32:50 GMT
It is MUCH better with a filter. You won't even believe it is the same headphone.
Article may take me a few weeks though. Still a lot to do and test, take pictures and write....
If you want I can post the filter and filter suggestions.
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proid
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Post by proid on Aug 27, 2013 13:45:15 GMT
It is MUCH better with a filter. You won't even believe it is the same headphone. Article may take me a few weeks though. Still a lot to do and test, take pictures and write.... If you want I can post the filter and filter suggestions. Yes, pls. I really want to try it now
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solderdude
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Post by solderdude on Aug 27, 2013 14:52:53 GMT
www.mediafire.com/view/2daavgjw9st9cds/HD681-EVO_filter.pdfIf you have any questions please ask. For experimental purposes replace R1, R2 for 100 Ohm potmeters. With felt on the driver you can replace L1,L2 with a jumper (omit) or use max 470uH The other values are intended for usage without the felt on the driver. I recommend to remove the felt.
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proid
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Post by proid on Aug 27, 2013 16:34:20 GMT
www.mediafire.com/view/2daavgjw9st9cds/HD681-EVO_filter.pdfIf you have any questions please ask. For experimental purposes replace R1, R2 for 100 Ohm potmeters. With felt on the driver you can replace L1,L2 with a jumper (omit) or use max 470uH The other values are intended for usage without the felt on the driver. I recommend to remove the felt. Thanks, i will try it tomorrow i report soon
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solderdude
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Post by solderdude on Aug 28, 2013 6:39:34 GMT
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Rabbit
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Post by Rabbit on Aug 28, 2013 6:56:56 GMT
My goodness Frans, it gets better all the time!! You've been busy.
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solderdude
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Post by solderdude on Aug 28, 2013 7:15:36 GMT
I still need to find out what mechanical mods can bring but think I am pretty close to a final result already.
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