Superlux HD662-EVO The Superlux HD662-EVO has a similar appearance as the HD681-EVO and is probably while it is called EVO as well !t has better "more modern loo#s$ than the ori%inal HD66& !n that aspect it certainly is an e'olution The cable on the EVO is detachable( which is an impro'ement o'er the ori%inal HD66& which had a non remo'able lon% cable They are a'ailable in blac# and white !t comes with a ) meter and a 1 meter cable which can also be combined to create an e'en lon%er cable *lso a clip is included so you can +ix the headphone plu% to the cord and can,t pull it out any more ersonally a +ind the remo'able cable .ust +ine as it is !t doesn,t come o++ easily and when t he wire %ets cau%ht it unplu%s itse l+ *las( the cable is microphonic This means tha t mechanical contact sounds( when the cable rubs a%ainst clothes +or instance( are trans+erred to the cups and can be heard durin% /uiet passa%es and silence This headphone also comes with %old-plated )0 to 6)mm TS .ac# connector * so+t carryin% pouch is also included *nother pleasant addition in the box is an extra set o+ 'elours pads Stoc# the HD66&-EVO comes with pleather pads already mounted The pleather "+a#e( 'inyl based leather$ is much so+ter and more compliant than the ori%inal HD66& pads *nother welcome impro'ement 2 The headband has a thin layer o+ rubber on the underside with ,air +illed cushions, !t is a bit more +riendly to +ollicularly challen%ed heads "li#e mine$ than the hard plastic one on the ori%inal HD66& The shiny sur+ace o+ the headphon e parts( +ortunately( are not a +in%erprint ma%nets but scratches will be /uite 'isible 3oo#s-wise it seems to be tar%eted at youn%er people or the classier loo#in% Hi-4i mar#et thou%h There are no 35 mar#in%s +or the non 'isual impaired users raille mar#in%s +or 3and are present thou%h Howe'er( Howe'er( when you hold the headphone in +ront o+ you and you can read the embossed word ,Superlux, on the t op o+ the headband "wire on the le+t side$ you ha'e it in the correct orientation( le+t( ri%ht wise in any case The impedance is around )6Ω which is excellent +or connectin% it to portable e/uipment !t has lar%e 07mm dri'ers which appear to di++er +rom the older dri'ers The ori%inal HD66& membrane has a di++erent colour and had a stic#er co'erin% almost o+ the dri'er with ,acoustic damper( please do not remo'e, written on it The HD66&-EVO dri'er "shown on the ri%ht$ has a )mm thic# +elt disc in +ront o+ the dri'er which is %lued on the dri'er around the ed%e The e++iciency is somewhat hi%her than that o+ the HD681-EVO so it plays sli%htly louder o n the same 'olume settin%( that is when comparin% both a+ter modi+ications !t plays loud enou%h +rom most portable de'ices de'ices such as mobile phones and small players The attenuation +rom outside noises is somewhat better than that o+ the HD681-EVO The latter is semi-closed and thus partly open due to ,ports, The HD66& is +ully closed Still some outside n oises lea# throu%h 'ia the pads The clampin% +orce is .ust ri%ht( it doesn,t clamp hard but also stays put when mo'in% your head They are a bit cheap plastic loo#in%5+eelin% The steel rods connectin% the ear-cups are thinner and can be bent and twisted more easily than those o+ the ori%inal HD66& E'en thou%h it does does ha'e a cheapish loo# about it you can bend the headphone in all #inds o+ positions and it always comes bac# in the ori%inal position "within limits o+ course$ The headphone seems sturdier than it appears to be based on its loo#s ! don,t thin# it will brea# or ha'e parts brea# o++ !n the end it is always about the com+ort and sound The com+o rt part is excellent 2 9O complaints there The sound is ,impressi'e, on +irst listen 9ote: this headphone wasn,t ,burned-in, be+ore listenin% and testin% and was recei'ed new in box re'ious experiments with newer Superlux headphones had shown that the headphones did not chan%e audibly o'er time so assume this one doesn,t either ! am sure some small chan%es occur durin% the +irst +ew minutes but doubt about audibility o+ such minor chan%es ;here the HD681-EVO "in stoc# condition$ was VE< bassy and dar# the HD66&-EVO is much more clearer soundin% !t,s li#e ha'in% a sub-woo+er strapped to your head 4or most the sound will be ,balanced, with a tout bass The stron% bass is deep " reaches lower than HD681-EVO$ but where the HD681-EVO sounds o'erly warm and bassy with subdued treble this one is much clearer without too much treble "so not splashy( sharp or sibilant$ The bass is somewhat dis-attached +rom the mids This has the ad'anta%e o+ the bass not bleedin% into the mids but also remo'es ,warmth, +rom 'oices and ,cohesion, in that important part o+ the +re/uency ran%e This ma#es the 'oices stand out a bit too unnatural "arti+icially o'erly ,clear,$ thus instruments and 'oices sound a bit too ,+orward, without bein% too loud The treble %i'es the headphone a detailed sound 1
Measurements of the stock HD662-EVO
The 'ersion described earlier( which had a sharp ed%e in the treble, was a p re-production sample ! recei'ed +rom Superlux directly The production 'ersion di++ers in that it doesn,t ha'e the sharp treble the pre-production model h ad The only di++erence is the )mm thic# +elt disc "the same one as used on the HD681-EVO$ which is %lued in +ront o+ the dri'er Durin% the e'aluation and modi+ication o+ the HD681-EVO it was clear the +elt is there to remo'e the treble pea# !t also remo'es the top end extension and ,openness, as well as the sense o+ ,air, a bit too much !n the HD681-EVO the +elt was completely remo 'ed and replaced with an electronic +ilter circuit "li#e in the modi+ied o ri%inal HD681$ *s an alternati'e to a +ilter "the HD681-EVO didn,t need as much +ilterin% as the ori%inal HD681$ the +e lt disc can be cut in hal+ and only one hal+ is %lued bac# onto the dri'er *nother ,side-e++ect, o+ the +elt disc is t hat the space between the dri'er and ear also is )mm less This could well ma#e the di++erence with touchin% or not touchin% the dri'er with your pinnae emo'in% the +elt disc ta#es some sli%ht e++ort and %uts !t is only %lued a round its ed%e and can be pried o++ Once remo'ed you end up with the same loo#s as the pre -production model ! tested earlier 3et,s see what the e++ect o+ this +elt disc is =easurement time 2
That doesn,t loo# bad 9otice it reaches 17H> ;hen one reali>es )7-?7H> is about as low as we can hear a tone than it is ob'ious those subbass notes are ele'ated by approx 8d Still the extension e'en below that still adds to the o'erall experience There is a small dip around &07H> "don,t mind the wi%%les +rom 67 to 177H>$ o+ -0d This ,disconnects, the bass somewhat +rom the rest o+ the music Ha'in% a small dip there is pre+erred o'er ha'in% a pea# there * pea# at that +re/uency ran%e results in mur#y bass bleedin% into the mids Still a smooth transition between 177H> and 1#H> would ha'e been more desirable as that would ma#e the sound more ,cohesi'e,( as in the bass not bein% ,separated, +rom the rest o+ the music * small risin% in +re/uency response between &77H> and 1#H> creates ,+orward, and ,open, soundin% mids !n terms o+ linearity o+ +re/uency response o+ his headphone is relati'ely ,+lat, +rom )77H> to @#H> compared to lots o+ other headphones around The small dip around )0#H> isn,t percei'ed as such nor 'ery audible The distortion at that +re/uency section does increase substantially "as can be seen +urther down this article$ and is audible with some recordin%s the headphone sound sli%htly more ,rou%h, compared to more expensi'e headphones "thin# +la%ships$ 4or well made recordin%s it doesn,t sound ,rou%h, at all thou%h( but nice and smooth The small and narrow pea# around A#H> also can %i'e the ,shimmer, o+ cymbals a 'ery sli%ht ,ed%e, but in most recordin%s it will %o unnoticed( Bertainly when you aren,t aware o+ the small pea#( or #now how the treble sounds on better "read some =CBH more expensi'e$ headphones *bo'e 11#H> the upper treble extension drops 0d This doesn,t appear to be that problematic and isn,t but it has a similar e++ect as pullin% down the 16 #H> slider o+ an e/uali>er by 0d This remo'es somethin% +rom the ,airy, sound ma#in% the nice ,shimmer, on cymbals sli%htly less appealin% and real Still .ust -0d is better than most e /ually priced headphones that tend to drop-o++ steeply beyond 1)#H> or so Do note that the %raphs here %o +rom 17H> to )7#H> where plots elsewhere %o +rom &7H> to &7#H> * drop-o++ abo'e &7#H> isn,t really audible but one should realise that many people +eel their D*B and recordin%s should be able to reach at least 07> should #now that there isn,t much ,li+e, in most headphones abo'e &7#H> * +ew exceptions exist thou%h( chec# out the 'arious measurements on the website +or this "lin# below$ https:55diyaudiohea'enwordpresscom5headphones5measurements5 &
Analysis
elow a +re/uency response plot o+ the same channel with the +elt in +ront o+ the dri'er and with the +elt remo'ed
The e++ect o+ the +elt is /uite ob'ious The +elt disc causes a sli%ht redu ction "+ew d$ between &77H> and 1#H> but is most e++ecti'e abo'e 6#H> *round &7#H> "who can actually hear that hi%h up $ the reduction is more than 17d emo'in% the +elt ma#es the sound much more ,detailed, but also %i'es most recordin%s a sharp ed%e The seemin%ly more detailed "+a#e detail$ sound is also /uite tirin% a+ter a while 3istenin% +ati%ue and some sli%ht sibilance "o'erly pronounced ,S, sounds$ are conse/uences o+ remo'in% the +elt disc *s the pre-production model that was e'aluated earlier did not ha'e this +elt disc it was too ,treble happy, To chec# i+ other chan%es were made to the production model below a comparati'e plot between the pre-production model and the "bou%ht at Thomann$ production model 3e+t channel only
The plots are /uite similar Do note that the dip around &07H> is already 0 d smaller that that o+ the pre-production model E'erythin% abo'e 077H> is actually /uite similar ass inte%ration o+ the production model is better than in the pre-production model where the mids had a weird sound to them The mids where much too ,clear5thin, and lac#ed more warmth and sounded much more ,dis-attached, than the production model which still has some o+ those e++ects thou%h noticeably less )
elow the distortion plot o+ the HD66&-EVO without +elt disc "on the le+t$ and the stoc# HD66&-EVO "on the ri%ht$
The bass distortion "around 07H>$ is reachin% 1 F This isn,t top le'el but there are many other headphones around with distortion le'els o+ well o'er 17F 4or%et the sharp spi#es at ?7H> and 67H> these are not there in reality *t 177H> the &nd harmonic distortion is already down to 7&F Hi%her harmonics drop below 77&F abo'e &77H> This means the harmonics there are at least @7d below the +undamental ;hen listenin% at a loud S3 "say A7d$ the harmonics will already be below the audible limit Somethin% that is more worryin% is t he distortion spi#e at ?#H> The sharp dip and pea# at that +re/uency shows less than desirable beha'iour o+ the dri'er The distortion pea#s reach )F This is audible The a'era%e amount o+ &nd harmonic distortion .ust around 7&F isn,t alarmin%ly hi%h nor desirably low 4or a headphone in this price class "around G ?7-$ it is /uite acceptable 4la%ship headphones will ha'e lower distortion le'els &nd harmonic distortion isn,t percei'ed as ,distortion, li#e in the sense o+ de%raded sound when well below 1F The reason +or that is that all instruments5'oices ha'e mu ch hi%her le'els o+ &nd harmonics by itsel+ which mas# the harmonics %enerated by the headphone itsel+ 3e'els abo'e a +ew percent can be percei'ed as a sli%ht ,rou%hness, or a less ,smooth, sound The +elt disc doesn,t appear to ha'e much in+luence on the distortion below 1#H> except around107H> where the +elt appears to increase distortion sli%htly Distortion le'els abo'e &#H> are sli%htly impro'ed elow the distortion plot o+ the HD66&-EVO without +elt disc "on the le+t$ and the pre-production HD66&-EVO "on the ri%ht$ uite similar in beha'iour except the pre-prod model has hi%her "almost 17F$ distortion at ?#H>
elow the BSD plots o+ the stoc# "with +e lt disc$ HD66&-EVO 3e+t channel and i%ht channel are superimposed
The problems at ?#H> are 'isible but aren,t rin%in% The pea# at A#H> is ob'ious a resonance issue but also not rin%in% too lon% ?
S/uarewa'e and impulse response di++erences between the HD66& without +elt disc "on the le+t$ and with the +elt disc "on the ri%ht
?7H> s/uare-wa'e HD66&-EVO "no +elt$ note: the measured le'els were clippin%
?7H> s/uare-wa'e stoc# HD66&-EVO note: the le'els were hal'ed to +it in the screen
??7H> s/uare-wa'e HD66&-EVO "no +elt$
??7H> s/uare-wa'e stoc# HD66&-EVO
177µs impulse HD66&-EVO "no +elt$
177µs impulse stoc#HD66&-EVO
The +elt clearly has a dampenin% in+luence on the dri'er in%in% is less se'ere and shorter li'ed =easurements on the +ollowin% pa%es are all made usin% the pre-production model which doesn,t di++er +rom the current model once the +elt has been remo'ed
0
The %ood news is that Superlux pro'ides both pleather and 'elours p ads with this headphone This is seldom se en in this price class !n most cases there are /uite some di++erences in tonal balance between pleather pads and 'elours pads elow the di++erences in +re/uency response between a HD66&-EVO with the +elt discs remo'ed usin% pleather pads and with 'elour pads
The mids and treble part is the same ass and subbass le'els are about )d lower with 'elour pads 4rom &07H> to o'er &7#H> the beha'iour is 'ery similar elow the BSD ";ater+all plot$ o+ the HD66&-EVO without the felt isc and with stoc# pleather pads( le+t and ri%ht are superimposed
The BSD is /uite ,messy, and the treble pea#s are pea#in% abo'e the plot There is rin%in% 'isible at 10#H>( ?#H> and around 8#H> elow the Spectrum plot which is more or less a water+all plot but loo #ed at +rom the top where the le'el is colour coded with the time pro%ressin% to the t op o+ the plot !n the BSD the time-scale is 0ms( in the plot below the time scale is 07ms
!n this plot the rin%in% at 10#H> is more ob'ious 6
=any people may still be /uite happy with the stoc# sound 3ots o+ bass( mids that ,stand out, and don,t sound ,mu++led, Treble with a a %ood le'el o+ presence a nd ,detail, and reasonably wide ste reo ima%e The bass won,t be a problem and sounds %ood albeit sli%htly north o+ neutral which is welcome to most listeners The mids are a bit to ,midran%y, and lac# warmth( cohesion and subtleties The treble is decent but lac#s upper end extension which re'eals itsel+ mostly in cymbals ;ithout the +elt disc the treble can be downri%ht nasty and sibilant with lesser recordin%s and5or music with lots o+ treble in it 4ortunately the dri'ers themsel'es ha'e lots o+ potential to satis+y the audiophile that doesn,t want to stretch their wallets This is where Superlux has the ed%e o'er many other manu+acturers with some o+ their headphones "HD681-EVO +or instance$ The +irst thin% that needs to be done is lowerin% the amount o+ treble in such a way that sibilance is remo'ed and see i+ other materials than the )mm thic# +elt can be used Various materials were tried and measured Synthetic +elt( paper hand#erchie+ paper( paper #itchen towel( co++ee +ilter and the +oam disc itsel+ which is +ound in +ront o+ the dri'er
elow a plot showin% the e++ect all these materials ha'e on the +re/uency re sponse
9o +ront +oam( without +elt disc( &mm thic# synthetic +elt( paper hand#erchie+( co++ee +ilter( & plies o+ toilet paper ;ith di++erent materials 'arious amounts o+ treble attenuation can be reached !t,s .ust a /uestion o+ pic#in% the ri%ht materials On the +ollowin% papers some comparisons between di++erent materials used and the st oc# HD66&-EVO The co++ee +ilter completely remo'es the treble pea# but also treble extension Two plies o+ so+t ")ply$ toilet paper seems to lower the treble pea# to similar amounts as the )mm +elt disc but doesn,t a++ect the upper treble as much as the )mm thic# +elt does *nother bonus is that the distance between the ear and dri'er is )mm bi%%er which may ma#e the di++erence between pinnae touchin% the dri'er or not The +ront +oam not only protects the dri'er +rom dust( dirt and hairs but also seems to ha'e a dampenin% e++ect !n these experiments the +ront +oam is always used combined with the paper materials @
Various tests results
no +elt disc I +oam disc 'ersus no +oam disc
no +elt disc 'ersus &mm thic# synthetic +elt
no +elt disc 'ersus ) plies o+ paper hand#erchie+ "tissue$
no +elt disc 'ersus co++ee +ilter
no +elt disc 'ersus "paper$ paper towel
tissue 5 hand#erchie+ 'ersus paper towel
The paper hand#erchie+ "tissue$ and paper towel lower the treble by a %ood 0d There is hardly any di++erence between the paper towel and the paper hand#erchie+ The co++ee +ilter mana%es to reduce the treble by 17d The & mm thic# synthetic +elt has almost no e++ect at all Just a small di++erence with the stoc# +oam disc ;hen listenin% to these 'arious materials it became ob'ious that the co++ee +ilter was too much The treble became borin%( a bit rou%h and had lost dynamics and spar#le The +elt didn,t %i'e much treble attenuation at all but remo'ed ,air, a bit too much The paper towel and hand#erchie+s "or & plies o+ so+t ") ply$ toilet paper$ seems to per+orm as desired 8
;hen the bass is lowered a bit the tonal balance becomes a bit better One "not the best$ way to lower the bass is by addin% dampin% materials to the rear o+ the ma%n et To do this the cups mu st be opened up The inside o+ the cups is shown on the ri%ht There are no dampin% materials on the cups nor on the ba++le 6 holes are 'isible which are co'ered with some #ind o+ dense b lac# paper on the +ront side The se holes are there to re+lect a certain part o+ the +re/uency spectrum bac# to the +ront to e/uali>e the +re/uency response and to ma#e the bass response less seal dependent &mm thic# +elt was placed in the cups( ri%ht behind the dri'er This ,bloc#ed, the little hole in the ma%net and altered the dampin% o+ the dri'er in an unesira!le way There simply isn,t enou%h +ree space behind the d ri'er
stoc# 'ersus +elt behind the dri'er
stoc# 'ersus +elt behind the dri'er 'ersus +elt in the recessed area
The bass was lowered but the subbass remained The risin% 4 between 177H> and 1#H> "almost 17d$ pro'ed to be a hu%e disappointment The mids became shrill and de'oid o+ any warmth ass le'els were way too low as well( only deep rumbles were still heard Blearly this was too much ampin" !n order to a'oid hi%her +re/uencies +rom re+lectin% to the cups bac# to the dri'er membrane +elt was only applied in the deeper "recessed$ area o+ the cup on both sides "see picture on pa%e 1)$ The +elt strips didn,t seem to do anythin% measurable nor appeared 'ery audible so there doesn,t seem to be a real need to open up the cups +or this modi+ication O+ course( playin% around with di++erent amounts o+ wool( cotton or other materials behind the dri'er are still an option and could yield results between the +elt and nothin% Then there are the 6 holes "ports$ to play with To determine what e++ect they ha'e the ports were sealed o++ usin% thic# plastic tape On the le+t compared to a stoc# dri'er "no +oam disc$ Sealin% the ports resulted in a +ew d more bass and about 0 d less ener%y between 1#H> and ?#H> This is somewhat encoura%in% as the risin% 4 between &77H> and 1#H> isn,t really desirable The mids aren,t ,warm, enou%h and sound dis-attached +orm the bass and are also sli%htly too ,accentuated, O+ course some air needs to be able to pass throu%h the ba++le so at least one hole should be ,open, to allow air the pressure to e/uali>e between the cup side and the ,ear chamber, side Some experimentin% showed lea'in% & holes open "so ? holes closed$ %a'e the most desirable e++ect ass le'els were barely hi%her and the area between ?77H> and ?#H> +lattened out a bit e++ecti'ely ma#in% the &77H> dip somewhat smaller and %a'e a more natural and ,inte%rated, mids with the bass To lower the bass .ust a +ew d the 'elours pads can be used Those are more com+o rtable and ha'e a %ood e++ect on the amount o+ bass unless you are a bass-head in which case the pleather pads may be more appealin% 3istenin% tests did show that the treble reduction with a ")-ply$ paper hand#erchie+( reduced the amount o+ treble5spar#le5air a bit too much emo'in% 1 p ly "lea'in% & plies in place$ p ro'ed to be optimal and yielded an excellent treble /uality5/uantity A
Moifications
The +inal set o+ modi+ications are real easy to do and do not e'en re/uire openin% up the headphones *ll that is needed is to remo'e the pads( tape ? holes shut( apply 2 plies o+ so+t toilet paper or paper hand#erchie+ and replace the pleather pads by the supplied 'elours pads Step 1: remo'e the pads This is 'ery easy to do Simply pull the pads o++ %ently
step &: Seal ? o+ the 6 holes usin% sturdy tape
Step ): cut out a piece "sheet$ o+ so+t toilet paper 5 hand#erchie+ and remo'e enou%h plies so there is only 2 plies o+ paper le+t
Step ?: ut the +oam disc on top o+ the paper and mount the 'elours pads
This is what you will end up with:
⇨
The impro'ement in sound /uality can be called substantial !t is clear that Superlux was able to impro'e their dri'er substantially The sound /uality o+ this HD66&-EVO "when modi+ied this way$ is much hi%her than that o+ both the "stoc# and modi+ied$ HD681 as well as the "stoc# and modi+ied$ HD681-EVO !t is also =CBH hi%her than that o+ the HD680 and other models To me this is THE best soundin% Superlux headphone yet 9ote: ! didn,t say THE best soundin% headphone Once modi+ied this "rather cheap$ headphone does beat many( many more expensi'e headphones in terms o+ o'erall sound /uality ! am truly impressed with its sound "once modi+ied$ O+ course it can,t compete with TOT3 headphones but it pun ches ;E33 *OVE other headphones at this and hi%her pricepoints +or sure !+ you are loo#in% +or some not expensi'e and +ully closed and nice soundin% headphones ! can hi%hly recommend this HD66&-EVO K but some sli%ht mo di+ications are essential to ma#e it sound ,Hi-4i, 17
Moification results #measurements$
4re/uency response o+ the modi+ied "4 holes taped shut + toilet paper instead of 3mm felt $ HD66&-EVO( le+t( ri%ht
elow the di++erences between the stoc# HD66&-EVO with pleather pads and the modi+ied HD66&-EVO with 'elours pads
Excellent sub-bass extension( well below 17H> 2 The bass le'el is lowered by usin% 'elours pads 4or those wantin% somewhat more bass the pleather pads may be more satis+actory Excellent bass response with a healthy( but small( boost that does not ,ble ed, into the mids This is partly because o+ the small dip around &77H> The dip .ust a bo'e &77H> is e++ecti'ely a +ew d smaller because o+ the 'elours pads as well The midran%e has become much +latter and isn,t slopin% upwards any more This results in =CBH better soundin% mids that are 'ery dynamic( ha'e an excellent clarity and sound 'ery ,li+eli#e, 9ot o'erly warm nor bri%ht Just per+ectly balanced The treble pea#s ha'e been completely remo'ed by the & layers o+ tissue paper ;hat remains are excellent hi%hs with a 'ery nice spar#le and lots o+ air and smooth details 9o sibilance( no +ati%ue( no shrill or harsh treble anywhere The sound o+ this modi+ied headphone punches VE< much abo'e its price point *ll that needs to be added is some paper and & pieces o+ cello tape !t is hard to belie'e that it only ta#es & 'ery minor alterations to impro'e this headphone
11
Distortion le'els also ha'e impro'ed somewhat On the le+t the stoc# HD66&-EVO on the ri%ht the modi+ied 'ersion
ass distortion around 07H> increased sli%htly when modi+ied but at these +re/uencies these le'els o+ distortion "&F$ aren,t that audible !n the 177-&77H> area the distortion went down +rom 70F to 7&F The distortion between 077H> and &#H> also decreased +rom 7&F to 7(1F There still is a distortion pea# around the ?#H> ,problem area, This is a dri'er issue The distortion le'els went +rom 0F to &0F which still is a si>eable impro'ement elow the BSD,s +rom the stoc# 'ersion "on the le+t$ 'ersus the modi+ied 'ersion "on the ri%ht$ le+t( ri%ht superimposed
Stoc# without )mm +elt disc
modi+ied
The part +rom 077H> to & #H> and the part abo'e ?#H> shows substantial impro'ements The ?#H> problems did not impro'e that much elow the s/uare-wa'e and impulse response plots o+ the stoc# HD66&-EVO
?7H> s/uare-wa'e stoc# HD66&-EVO
??7H> s/uare-wa'e stoc# HD66&-EVO
177 µs impulse stoc# HD66&-EVO
elow the s/uare-wa'e and impulse response plots o+ the modi+ied HD66&-EVO
?7H> s/uare-wa'e stoc# HD66&-EVO
??7H> s/uare-wa'e stoc# HD66&-EVO
177 µs impulse stoc# HD66&-EVO
ass le'els still a bit exa%%erated but closer The ??7H> shows a nice attac#5speed and much less rin%in% The impulse response is much impro'ed( much less o'ershoot and doesn,t rin% nearly as much 1&
elow the spectrum plot o+ the stoc# HD66&-EVO "without the +elt disc$
The rin%in% around 10#H> is clearly 'isible !t ta#es )7ms be+ore the le'el dropped 07d *lso the ?#H> rin%in% ta#es about 17ms be+ore reachin% -07d elow the spectrum plot o+ the modi+ied HD66&-EVO The 1?#H> rin%in% is shortened considerably The ?#H> rin%in% isn,t much shorter thou%h The treble area abo'e @#H> did impro'e as well
4or those who are a little more darin% and #now how to solder there is one more modi+ication that can be applied which also has a positi'e e++ect This re/uires openin% the cups There-in lies the little sna% where ha'in% decent solderin% s#ills mi%ht be needed The wires inside the cups are /uite short and thus are limitin% the distance you can li+t the dri'er away +rom the cups Bhances are you will rip o++ one or both wires +rom the dri'er The dri'er wires are a lso %lued onto the dri'er but still ! mana%ed to brea# o++ one o+ the wires +rom the dri'er whilst not usin% any +orce The cup modi+ication consists o+ applyin% ,anti-re+lecti'e, materials on recessed part o+ the cups !n this case &mm thic# synthetic +elt was used !t is %lued to the cup usin% double sided tape but %lue can also be used The anti-re+lection +elt also ma#es the amount o+ air behind the dri'er a bit less which a++ects the amount o+ bass a tiny bit as well ;hen you want a little less bass and to lower the &77H> dip somewhat you could put a little bit o+ &mm thic# open cell +oam behind the dri'er ma%net but you will loose some o+ the impressi'e bass as a result So this modi+ication will only be interestin% +o r those that +eel it has way too much bass O'erdoin% it will #ill the bass so some experimentin% may be re/uired The plots o+ this headphone are all made with +elt inside the cups but 9OT behind the dri'er So with +elt applied as in the p icture on the ri%ht
1)
Measurements of this moification%
elow the +re/uency response o+ the moifie HD66&-EVO with the +ollowin% modi+ications: 1: 4elt disc remo'ed and rep laced with & plies o+ toilet paper &: ? o+ the 6 holes in the ba++le sealed o++ with & layers o+ ,box-tape, on the inside o + the ba++le ): &mm thic# +elt taped "usin% doubled side tape$ on the lower parts inside the cup ?: leather pads used
*s can be seen the dip in the &07H> area is %one in the later HD66&-EVO 'ersion "the ones with the +elt in +ront o+ the dri'er$ ass and mids inte%rate really well 9o dis-attached bass and the mids sound sli%htly more ,real, and ,+uller, The sli%htly lower S3 between 10#H> and @#H> is a positi'e thin% +o r many recordin%s that ha'e a tendency to be shouty or shrill Tapin% o++ the holes e/uali>es the mids * sli%htly lower le'el usually ma#es these recordin%s sound more pleasant and doesn,t ha'e a ne%ati'e impact on well made recordin%s TOT3 headphone li#e the Sennheiser HD877 as well as many o+ the better orthodynamic headphones also ha'e a sli%htly lower le'el in the same +re/uency ran%e The toilet paper replacin% the +e lt yields a similar narrow A#H> pea # as the )mm +elt disc has CT doesn,t ma#e the upper treble extension drop-o++ by about 0d resultin% in better cymbals reproduction and sense o+ ,air, elow the di++erence between a modi+ied HD66&-EVO "'elours pads$ and the stoc# HD66&-EVO "with +elt disc$
This plot shows the bass boost is remo'ed due to the +elt inside the cups !+ you li#e more bass this mod is not +or you The dip around &07H> is %one and instead o+ slowly risin% +re/uency response between &77H> and )#H> the +re/uency response is slowly slopin% downwards +rom 17H> to )#H> ecause o+ this the mids are more neutral and sli%htly less ,bri%ht, The di++erence in amount o+ upper treble "L 17#H>$ is ob'ious 1?
ads also ha'e some in+luence on the o'erall tonal balance elow the di++erences between a modi+ied HD66&-EVO with pleather pads and with 'elours pads
The sli%htly raised sub-bass is lowered about &d when usin% 'elours pads and is now "audibly$ on a ,+lat, le'el Still extendin% all the way down to 17H> 2 The treble also is sli%htly di++erent( sli%htly smoother soundin% elow the BSD o+ the stoc# HD66&-EVO "with +elt d isc$ on the le+t and the mo di+ied 'ersion on the ri%ht
The rin%in% between 077H> and &#H> has somewhat impro'ed 9o substantial di++erences in the hi%her +re/uencies when it concerns rin%in% elow the distortion plots o+ the stoc# HD66&-EVO "with +elt disc$ on the le+t and the modi+ied 'ersion on the ri%ht
The &nd harmonic distortion didn,t chan%e much except +or the area between 177H> and &77H> where the modi+ied 'ersion is somewhat better *lso the hi%her harmonics abo'e )#H> has substantially impro'ed The )rd harmonic distortion between 07H> and &77H> is sli%htly worse due to a lesser amount o+ air inside the closed cups Summary
The sound /uality o+ this "modi+ied$ HD66&-EVO has impro'ed from: Having a somewhat dis-attached but fun bass but lacking 'warmth' and 'cohesion'. Voices and instruments that stand out a bit 'unnatural' but having good clarity. ue to a slightly rolled off upper treble 'air' and 'cymbals' are slightly lacking realism. to& !ealistic bass response with good subbass e"tension #he midrange is improved $more cohesive%& uite dynamic& has a good clarity and sounds very 'real'. (ot 'warm' nor 'cold'. )ust * properly balanced and fun. #he treble is of good uality with a very nice sparkle and lots of air as well as sounding smooth and detailed. (o sibilance& no fatigue& no shrill or harsh treble anywhere. Solderdude M https:55diyaudiohea'enwordpresscom5
10
