Headphone Correction Filter board

Hi Mark,

Welcome to the forum.

Bare boards can be purchased from me directly or (for the US) from Jeremy (garage1217) which is known here as member 'jhelms'.
Jeremy can also make assembled units.
For European customers for assembled units one of forum admins 'Javier' can be contacted.

Just click on the names for contact details.

I recently acquired a nice pair of used hifiman HE400 at a decent price in order to test out the world of planar-magnetics. Needless to say, I'm now hooked
OLDSON, your post said you were going to review the lcd-2/3 he500/6 last year 2013. If you got around to doing that , I'd like to know your opinions.

As much as I do like he400, EQ is a must for me, especially using HD600 as my reference HPs (with no EQ).

Question: is the he400 not on the filter list because its FR is to wild to be tamed ?
If so, I would be looking at another "relatively affordable" pair of used planar magnetics, possibly he500 which I see is on the filter list.

The HE400 can be filtered.
A slightly different compensation from HE500 is needed.
I could make a filter suggestion specifically for it.

All the Hifiman (and also true for Audeze) have very similar compensation.

The K701 and D2000 just happen to be 2 of the headphones that are difficult to correct due to the nature of their problems.
The K701 seems to improve acc. to Micmacmo though, more/better lows and less sibilant but as the sibilance is decreased also the 'detailing' is less as these go hand in hand.

Of course the filters can also be changed somewhat to suit ones taste or to get closer the Olive-Welti target or other compensations.
The DT880 can be corrected well I reckon.

Before you start on boards I recommend to simulate the correction curve with an equalizer.
Play a bit with the settings and perhaps you can even find a better setting or find out the headphones do not react well to corrections.

I owned K701, DT880 and heard D2000 and D7000.
The K701 and DT880 were sold in the end because of lack of bass extension.

Something between the DT880/K701 and D2000 (with slightly less highs) would be close to ideal.
Compensation can get you there or at least come very close.

for a course idea of how the tonal balance will become software and hardware will be O.K. as long as it has bands that come close the those that need some correction.

If you like the tonal balance with that EQ or have found a somewhat different setting then a filter can be constructed that makes a closer matching correction.
The filter board has the advantage that it has less phase shifts and more exact compensation than analog graphic EQ.
Some digital EQ has some side effects as well which the board doesn't have.

a very simple player for instance with a 'decent' EQ is AIMP or VLC.
There are better players, like foobar etc but the ones mentioned above are 'lightweight' and easy to install/remove.

The K701 has 2 narrow problem areas right next to each other. The higher one is the most obnoxious one and the filter can only take care of 1.

As you can see it needs compensation for the lows (a LOT of you want to reach Olive-Welti which is close to the 'target' in this plot.
2.5k and 5k-10k are the main problem areas and give these cans the idea they are highly detailed (5k-10k) and make the mids sound so forward (2.5k)
It also lacks some air WHEN these peaks are compensated as the lack of air (HF extension above 12k) is masked by the peak at 10kHz.
The fact that it needs to narrow peaks corrected and quite some bass boost makes it difficult to correct as you also take away it's strong points (detail and spaciousness).
A bit like a filter corrected HD800 which will loose its hyper detail (as that is caused by the elevated treble part).

The D2000 can be corrected somewhat but the bass remains 'flabby' to me (perhaps not so with Lawtons mods) and indeed may need other compensation which you would have to figure out.

De D2000 actually needs a 'lift' (like the T50RP's) and the highs lowered slightly.
The duality about that dip is that it is actually a resonance in disguise meaning it rings there.
So IF you pull up the sliders there the resonance becomes more pronounced.
This is why it is difficult to correct the Dx000

The DT880

basically needs its peak removed and some gentle corrective measures to sound good and responds better to it than the other two.
Removing the peak, as with the K701, also removes some of the air and hyper (fake) detail BUT the DT880 can show some real fine details (like the HD650 can as well when not 'overpowered' by the lows.


AIMP has more frequency bands than VLC (I don't do i-things so don't know about that) so you may want to give that one a try.
Installs quickly without going deep into Windhose and uninstall is without problems.

I liked the DT880 and thought it sounded good with EQ, also easier to compensate.
The headphones that just need a gentle nudge and do not need narrow EQ bands do compensate better.

Between D2000, DT880 and K701 I prefer the tonal balance/sound sig of the D2000 the most.
All of them (as are more expensive headphones) are flawed in some way.

I could very well live with an EQ'ed DT880 but my personal preference lies in planar speakers and headphones (the latter compensated ones)