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Post by c61746961 on Apr 9, 2015 15:12:57 GMT
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solderdude
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measureutternutter
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Post by solderdude on Apr 9, 2015 18:51:28 GMT
I once measured Stratos T50RP with HM5 pads and measured like this: I have corrected many headphones 'flat' and none of them has ever sounded thin and bright. Chances are the headphone has too much treble and may lack subbass but most likely isn't flat. Of course there is also taste of course. Do you have access to a DT250-250 or HD580/HD600 ? The plot is showing a correction curve to compensate for room effects. A speaker that is flat in an anechoic room at 1m may sound like this in a perfectly corrected room. Are you looking for a passive filter inline with the headphone itself ? It is very similar to using and amplifier with the treble control set to -3 and bass control to +2dB It is possible to design a passive filter that approximates this curve but it may be better to correct only those parts that need correcting. Building a test rig is essential for this. This is also shown by the LEAPS Startocaster has made since he measures his own stuff. His 'open' T50RP is simply astonishing.
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Post by c61746961 on Apr 9, 2015 20:40:13 GMT
Thanks! Are those the HM5 velour pads?, I tried the pleather ones and they do sound bloated in the bass and peaky in the treble. I have a setup similar to his latest mods with the stock enclosure, which use the velour HM5 pads mounted with a sock and some felt for 'controlled' leaking. Can't measure yet but mine sound considerably smoother than before (SRH840 pads), specially in the treble. I do have access to the DT250-250 that you measured, but they're not with me right now, I will do an A/B once I have the chance.
My goal is to have a flat-measuring headphone like stratocaster's with a slow -5dB roll-off filter to approximate that curve, I think it's more to my taste since I wanted slightly more bass than the DT250 offered and my tests with PEQ have been very positive so far. A passive circuit that fits inside the enclosure or a very small box would be ideal.
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solderdude
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Post by solderdude on Apr 9, 2015 21:12:54 GMT
They were the pleather pads.
The DT250-250 is close to flat and can give you an idea of the correct tonal balance. It does sound slightly 'thin' in the bass (as does the modified K550) and the treble isn't that refined but tonally it is 'correct'.
You could correct headphones for the 'missing 6dB effect' a bit like the GE bass correction. That requires only a lift in the bass (if the rest is flat).
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Post by c61746961 on Apr 9, 2015 21:55:29 GMT
Yeah, I have applied the bass lift via PEQ but there are instances where it does not work as I would like, however, the gentle downward curve is working very good for me so far, and it's just a 5 dB difference from top to bottom... Which one is easier to implement with a correction circuit?, I'd like to not depend on PEQ or batteries if at all possible. You can also point me in the general direction of analog filter design and see if I can help myself Thanks.
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solderdude
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Post by solderdude on Apr 10, 2015 17:53:01 GMT
the upper one is for between source and amp, the bottom one for T50RP ONLY and only a version with a DC resistance of around 56 Ohm ( +/- 4 Ohm)
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Post by c61746961 on Apr 10, 2015 18:05:54 GMT
Wow, man, you really go out of your way to help us... I'm very grateful. What kind of resistors and capacitors should I be looking for?, 1% tolerance is OK?
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solderdude
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Post by solderdude on Apr 10, 2015 18:57:25 GMT
Wow, man, you really go out of your way to help us... I'm very grateful. What kind of resistors and capacitors should I be looking for?, 1% tolerance is OK? Resistors 5% is already O.K, capacitors +/-5% or even +/-10% will do. The 2.7uF may have to be a 2.2uF + 470nF in parallel if hard to find. For the version in series with the T50RP the caps should be rated >25V and film type.
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Post by c61746961 on Apr 10, 2015 19:09:16 GMT
Thanks again.
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Post by c61746961 on Nov 12, 2015 19:34:21 GMT
I have a setup similar to his latest mods with the stock enclosure, which use the velour HM5 pads mounted with a sock and some felt for 'controlled' leaking. Can't measure yet but mine sound considerably smoother than before (SRH840 pads), specially in the treble. Finally got my hands on a mic (minidsp UMIK-1) and built myself a solid plate measurement rig. Here's what the FR of my modded T50RP used to look like with my take on the 'stratopads': Here it is now: I still intend to reduce the area between 2-10 KHz a few dB because some recordings sound kinda hot there. I don't why it took me so long to build this, it was built and running in 1 hour. I'm still considering building the circuit you graciously traced for me, it makes for a nice, relaxed listen. Thanks for being an inspiration, Frans Attachments:
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solderdude
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Post by solderdude on Nov 12, 2015 21:41:18 GMT
Those pads seem to remove the 3kHz dip quite effectively. Treble extension is almost impossible to achieve without active filtering though.
A measurement rig takes so much guessing out of modding.
The difficult part is getting the calibration right. Just sticking a microphone intended for free air measurements on a sealed baffle does strange things with the measured bass response.
I recommend to measure a 'well known' headphone like HD600 or HD650 and compare your own measurements with those using real calibrated HATS. Most home made measurement rigs make HD600's appear to have flat bass extension down to 20Hz which really isn't the case. A properly padded T50RP sure can reach 20Hz flat though.
Do you have other interesting headphones you measured ? This helps getting a feel for the test rig...
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Post by c61746961 on Nov 12, 2015 22:02:08 GMT
Yeah, here's a measurement of the Porta Pro with a light clamp: It does seem to be up 5 dB at 20Hz compared to your plots.
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Post by c61746961 on Nov 12, 2015 22:08:39 GMT
Let's keep this discussion on the other thread
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