Ho me
N ews
Contact
Sa les
Modulus
Modulus – paper and aluminium at their best !
This loudspeak er combines two comple te ly differ ent ty pe s of ca bine t lo ading with complete ly di ffere nt ty pes of driv er mate ria l. The
re sult, afte r a long path o f optimisati on, is the best o f bo th wor lds.
The tweeter
The Ce ler itas RB100 a.k.a. Aur um Ca ntus G3- Si is a pur e aluminium ribbon twee ter. It has a v er y lightwe ight m ovi ng ma ss made of
an aluminium ribbo n, giv ing a ve ry ex tende d fr eque ncy r espo nse and tr ebl e with lo ts of “ai r”. It uses N 45 N dFe B magne t bars either
side o f the ribbon that also add to its 99dB/ W/M high e fficiency. The RB100 / G3Si has goo d wi de hor izonta l dispe rsion but due to the
phy sica l shape of the ri bbo n it is l imite d in v ertica l dispe rsion, so it is impor ta nt that the tweete r is a t e ar height. This ma y mea n that
the ba ss ca bine t di mensions ma y need to be alte re d to match yo ur listening height.
The mid-woo fer
The Se as C A12R CY - H1152 is a bass-midrange dri ver with a na tural rubber surr ound and hand coate d pa pe r co ne with co ate d fa bri c
dust ca p to r educe re sonances a nd distor tion. The large magnet sy ste m for ms a symme trical dr ivi ng for ce a cco mpli shed thr ough a
specia l co il winding technique for the vo ice co il giv ing ex ce lle nt line ari ty. A v ery l arge magne t syste m (tha t I made eve n la rger by
adding a second ma gnet) prov ide s a re asona ble e fficie ncy and a lo w Q. The extr eme ly sti ff a nd sta ble i njectio n mo ul ded me tal ba sket
ke eps the cr itical compo nents in pe rfect a lignme nt. Large windo ws in the baske t bo th a bov e and belo w the spider re duce so und
re fle ction, a ir fl ow no ise and ca vi ty r esona nce to a minimum. The e xtra magne t Se as ty pe H 1120 raises the magne t for ce Bl fro m
6,35 to 6,85 – ne arl y 10% mor e, I had the impr ession tha t i t ma de the CA12RCY sound a little mo re dynamic with a li ttl e ex tra
“bite”. The a cce lera tion fa cto r gro ws from an alr ea dy impre ssive 1041 to a v ery nice 1123. Effi ci ency o f the dr ive r also rise s a bit by
0,65dB.
The woofer
The Se as C A26R E4X - H1316 is a 26cm wo ofer. The classical manual ly fr ont co ated paper cone and ma tching natura l r ubbe r sur round
pr oduce a smoo th re sponse and re duce po te ntial re sonance pro bl ems. A fo ur -la yer v oice coil prov ide s a wel l-behav ed ro ll off
cha racte ristic. A lar ge magnet sy ste m give s good se nsitiv ity and tra nsie nt r espo nse. An e xtre mely stiff and stable injection moulded
meta l baske t k ee ps the critica l co mpone nts in perfect ali gnment. La rge windows i n the ba sk et both above a nd bel ow the spi de r r educe
sound refle ctio n, ai r flo w noi se a nd ca vity re sonance to a minimum.
The cabinet ins ide and out
The cabinets we re constructe d by H uber t Ke lle r fro m F rance and ma de of thi ck 22mm m df cov ere d with a n ex tra la yer o f 10m m mdf,
br inging the tota l wa ll thi ck ness to 32mm. Originall y the design incorpora ted a n open-backe d midr ange e nclo sur e si milar to the Fo ca l
Audi om designs fo r ex ampl e but during the tuni ng o f the sy ste m this type of midrange enclosure showed sev er e sta nding wave
pr oblems tha t could o nly be ta ck led by heav y stuffi ng o f the midr ange e nclo sur e. This ro bbed the system of its dy na mic natur e. So we
de ci de d to go open-baffl e. La ter on yo u will see that the open-baffle mi dra nge is v er y cr itical in positio n a nd a mount o f da mpi ng
mate ria l (fe lt in this ca se ) but o nce done right e ver ything clicks into pla ce a nd you are r ewar de d with a n ex trem ely o pen, dynam ic
and col our-fre e midra nge . The sha pe o f the ba ffle is a co mbinati on o f functio na lity a nd a esthetics. The ba ffle sits o n to p of the woo fe r
enclosure v ia three spike s. The woofer e ncl osur e is mo re strai ghtfo rwar d cl osed box of 50 litre s with inte rnal bracing. The Q o f the
woo fe r se cti on i s tune d to 0,58 tha t is a goo d compr omise betwee n ma ximum fla t r espo nse (Qtc=0,707) and be st pulse re sponse
(Qtc=0,5). The Sea s CA26RE4X wil l wo rk in anything up to about 80 litre s, also the height of the wo ofer enclo sure wi ll dete rmine the
optimum l iste ning he ight of the spe ak er. Idea lly the centre o f the o pe n-ba ffle should be at ear hei ght so y ou a re free to change the
di mensions o f the wo ofer cabinet to match y our si tua tion the best. Al l dimensio ns are based o n the Fi bo na cci Numbers 3, 5,8,13,etc. I
have found these to be v isually plea sing and acousticall y ide al for spre ading out the standi ng wa ves to less cri ti ca l interv als. The
da mping ma teri al in the wo ofer enclosure consists of loo se ly filling the enclo sure wi th bo nded a cetate fibre lik e Sonofil. The midrange
ba ffle has a 15mm thick he av y fo am lay er on the ho rizo nta l pla te to cut refle cti ons o ff this se ctio n. Furthe rmor e the mi dra nge dr ive r
do uble ma gnet is cov er ed with a 4- 5mm thick lay er of fe lt. All inter nal wiring is si lve r-plate d ox yge n free co ppe r in P TF E.
Cross over.
This cr osso ve r took a l ot of twea ki ng to get right. The open-baffle mi dra nge pr oduce s a lot mor e midr ange e nergy in the ro om than a
norma l cl osed box ev en tho ugh the o n- axi s re sponse do esn’t sugge st so. In the e nd the cro sso ver turne d out to be a re lativ ely simple
two-wa y se rie s crossov er with a para lle l ne twork for the woo fe r added cr eati ng a 2.5-way system. The woofer sectio n is basical ly a
simple 1st or de r ne twork wi th an RC-netwo rk to compensa te the inducti ve ri se o f the woofer v oice -coil impeda nce . Fur the rmor e an
LCR-netwo rk is added to flatte n the impeda nce pea k at Fb so that the 4,7mH inducto r will wor k pro pe rly. F inally a nother LCR-ne twork
is place d dir ectly acro ss the i nput te rminal s to fl atten the ove ral l i mpedance to mak e an a mpl ifi er fr iendly lo ad (see i mpedance
cur ve ).
Cross over compo nen ts:
L1 = 0,68 mH Inte rtechnik Trite c inductor 3,5 mm wi re or So len Per fe ct Lay or Goe rtz CFI 14AW G, R = +/- 0,15 ohms
L2 = 1,20 mH Inte rtechnik Trite c inductor 3,5 mm wi re or Mundorf C FC-10 or Goe rtz CFI 12AW G, R = +/- 0,15 ohms
L3 = 4,7 mH Inte rte chnik Tor oba r inductor, R = 0,20 o hms
L4 = 18 mH fer rite- co re inducto r, R = 3,5 ohms
L5 = 0,47 mH air- co re inducto r, R = 0,57 ohms
C1 = 10uF M undorf M-Ca p Supr eme Sil ver /Oil capa citor
C2 = 0,01uF Vishay MKP 1837 po lypropyle ne fo il ca pa ci to r
C3 = 5,6uF Mundo rf M- Cap S upre me or Interte chnik Audyn C ap Pl us po lypropyle ne fo il ca pa ci tor (to lera nce ma x 2%)
C4 = 0,01uF Vishay MKP 1837 po lypropyle ne fo il ca pa ci to r
C5 = 47uF standard M KP po lypro pyl ene fo il capa citor
C6 = 420uF bi-pola r ca pa cito r (390uF e lco + 33uF M KT pa ral lel)
C7 = 33uF M KP po lypro pyl ene fo il capa ci tor
R1 = 10 o hms, 10 wa tts carbon fil m re sisto r
R2 = 3,9 ohms, 10 watts ca rbo n film resistor
R3 = 5,0 ohms ( 2x 10 ohms pa ra llel ), 10 wa tts ca rbon film re si sto r
R4 = 5,6 ohms, 10 watts ce ment r esistor
R5 = 5,0 ohms ( 2x 10 ohms pa ra llel ), 20 wa tts ce ment resistor
R6 = 7,5 ohms ( 2x 15 ohms pa ra llel ), 10 wa tts ce ment resistor
The
crossov ers with the se par ate LCR netwo rk mounted o n the ba ck pane l.
Lis tening resu lt s from the owner:
He re a re comme nts abo ut the spe ake r made by the cur rent owner; this also include s the last sta ge of twe ak ing of the spe ake r at his
house:
“So , as pro mise d, he re ar e my impre ssio ns after filte r co mpone nts burn-in: Re membe r, when we first talke d about this project I hoped
to ge t some thing mo re dy namical tha n my present (ve ry goo d) 2-way k it. Then, y ou aske d me wha t a re my ma in liste ning
pr efere nce s; I answere d: dynamic, soundstages, accele ration, deta ils, no fatigue : TARGET IS REACHED for EACH of them, a nd ev en
MORE: The se spe ak ers let me fe el tha t I'm listening to an almost per fe ct system: what I me an is tha t a ll the criterio ns are a t the to p
BU T all is included in this k ind o f "o neness" you talke d about the ser ies filters; music flows and all the sounds are r elate d ones to the
othe rs in a per fe ct co here ncy .
Yo u got a ver y REVEALING spea ke r, which the first quality is its "P RESENCE" . I think this quality is dir ectly rela ted to the abse nce o f
bo x co lor ation, to the "spe ed" o f the mid-drive r and twee ter, to the we ll da mpe ned ba ss loading and ev idently to the filter design: it's a
true CLEARN ESS, not an ar te fa ct, i.e . the mids a ren't " pr ojected" ; yo u go t the best o f ea ch driv er and succe ede d to cance l the ir
de fe cts: this is pr oo f of y our de sign ma ste ring. Co mpa ring to my 2- way , the re a re mor e de tails in mids and tre bles, tighte r bass a nd
tra nsients a re a mazing. A lso: a goo d se nsitivity a nd a lmost no tro uble when play ed at high le ve ls. Ima ge a nd so undsta ges gro wn up
with the liste ning lev el allowing a ve ry re alistic musical e ve nt. I fee l the "o ne ness" o f the so unds pa rticula rly in this soundstages-ra nge :
it's something new to m y ear s.”
“Two (ve ry slight) we ak ness that I hope pe rhaps to re duce with yo ur a dv ice s:
- Bass: ye s, co uld be a little stro nger a nd dee per : once aga in, we ha ve the same prefer ences...but I know that with these lo ading
vo lume a nd driv er yo u couldn't mak e more in this a re a. H owev er , ba ss is tight, unco lo ured ( no box r esona nce s) a nd I pr efer this than
a less dampe d ba ss-r ange . But...do y ou believ e I could "play " with stuffing? If ye s, in what way? (I hav e no e xperie nce with closed
loa dings)
- Uppe rmid at high listening le ve ls be co mes v er y slightly "ho wling" , BU T ONLY o n some cds; Did y ou tr y to da mp the ma gnets with
some felt o r fo am, a nd/o r the r ea r side of the open-baffle ? If no t, do y ou believ e I should try it, o r do yo u gue ss this will de le te some
ae ra tio n? P le ase, don't think I am no t fully sa tisfied about your wor k, I AM, just a m I wonde ring to mak e the M odulus the most
pe rfectly ada pte d to my ea rs, electro nics a nd roo m.”
This wa s la ter foll owed up by the se co mments:
“If y ou are the boss in filte ring, I be gin to be a bo ss in FF T ( Final Fine-Tuning), ha- ha :
- re move d the 2 little pieces of stuffing inside the 2 upper cav itie s o f the bass e nclosure , letting the m ain walls fre e, a s y ou a dv ise d:
go t slightly mor e deta ils and spl par ticular ly in ba ss which, in my ro om, ma tche s pe rfectly mids a nd tr eble s, witho ut any
bo ominess...a nd no lo ose of sub- ba ss....
- lea ne d the entire spea ke r back ward with 2 huge cones-fee t in fro nt and a double d nut in ba ck: slightly r educes the a mount o f uppertre bles (ev en in my "dead" ro om).
- re move d the fe lt ring be hind the CA12 and re placed with a thin (4-5mm, not more ) lay er of felt cove ring the entire ferr ite : reduce s
simila rly the mid-e mphasis than the felt ring but ope ns the so und mo re .
Re sult: Ah, PERF EC TION ?! ha -ha. I mo destly advice yo u to write a few wo rds about this ma tter on yo ur site, no t to say my
configuration is the be st in diffe re nt ro oms but just say that it's incre dible how a (this?) spea ker can be depending of a few pie ce s of
stuffing/felt! W orth the effo rt! W hen I liste n to the Modulus, I sa y to me: some whe re it's not norma l to be able to fre ely ge t this
sound...”
Again a little la ter ano the r fo llo w up with the se comme nts:
”Yes, I know...neve r sa y "fina l", whate ve r matter it is, twe aking a P rogress ( ha-ha ) o r liste ning to the Modulus (hum hum). Excuse me
ple ase with what fo llo ws:
Eve n if on a fe w cds the r esult in te rm of fre quencies balance is pe rfect, it is no t the case on other s. A fte r te sting a lot of
configurations abo ut pla cement and ba ss stuffing, I fina lly arr iv ed to ...your last se tup, it’s to say with a ll the stuffing yo u pla ce d inside
the ba ss enclo sur e: this give s the tighter a nd le ss reso na nt bass. But some thing wasn't " in place " with so me cds, the so und wa s
sometime s re ally too prese nt, so I play ed with the re ar o f the mid-drive r: the last setup that give s me satisfa ctio n is the CA12 magne t
cove re d with so me fe lt: the soundsta ges, a era tion, details a nd dyna mics a re bea utiful. I fina lly fixe d the pro blem: when I'm listening to
cds with a lo t o f tre ble, a nd only with them, the sound be co mes to be too har sh: pla cing mo re felt r ea r the mid do esn't r eally help a nd
ea ts de tails.
SO MY MAIN P ROBLEM IS THE TREBLES SP L! I guess this can co me be ca use I liste n re lative ly clo se to the spe ake rs in the wa y to ge t
the be st so undstage s.”
The n finally :
”Tha nks a ga in, the a dded pa ra lle l 33ohms wo rks ver y well with my Tar a labs! Quie ter on all my cds, without loosing any de tails o r
dy namics, a subjective fulle r and mor e de tailed bass ra nge but "sna ps" re main, pe rfect with my R oge rs, some time s (v er y) slightly o n
the da rk side with my SKA. Also a n a lmo st grea ter SOU NDSTAGIN G !!!. A ll in all, I'm now R EA LLY FU LLY SATISFIED.”
Measurement s
Fi lter functio n curv e 20-20.000Hz; ho rizo ntal divisio n 5 dB, unfilter ed curv es in bla ck . Ov era ll (r ed) a v ery smooth o utput l eve l
within +/-1dB with an effici ency of abo ut 86,5dB. Cr ossove r po ints a re centre d at a bout 350H z and 2200H z. W hat ca n be see n is the
la rge ove rla p betwee n the woo fe r (gree n-le ft) a nd midrange (blue) outputs; this is done to compe nsa te the lo sse s a t lowe r
freque nci es of the open-baffl e midrange dr ive r. Also y ou ca n se e that the hi gh effi ci ency of the twee ter (gr een- right) tha t needed to
be bro ught do wn to a matchi ng lev el. The se curv es are take n ne ar fie ld because the nature o f the o pe n- ba ffle ma de i t to o difficult to
mak e any mea ningful curve s when measure d at sta ndar d distances. Be low yo u will find the fa r-fiel d whi te no ise sy ste m output.
Impe da nce curve 20-20.000Hz; ho rizo nta l div isi on 2 ohms a nd co rre sponding phase hor izontal divisio n 15 degree s. The nomina l
impeda nce i s ex treme ly smoo th and ra nge s fr om 4 o hms in the ba ss to 7 o hms in the tre ble ; impe da nce minimum is 3.9 ohms at
20Hz. The ele ctr ica l phase is wi thi n +/- 15 degree s ma king a ve ry e asy loa d fo r most a mpli fie rs.
This raw non-smoo the d white noise mea sur ement was ta ken at 2 me tres micropho ne distance with both spea ker s pl ayi ng. The
spea ke rs we re al so 2 metre s a par t ther efor e fo rming an equa l sided tr iangle be twe en the mi cr opho ne and the two speak er s. I be lie ve
this to give a mo re re ali stic pre sentatio n o f the “cha racter ” of the spe ake r. S uch a n a pproa ch ca n nev er prov ide " abso lute" da ta about
a spea ke r's perfor mance, because it a lso inco rpora tes a few minor r eflections – ev en wi th the ga ted MLS me asur ing techni que I use
yo u can’t remo ve the ro om co mple tely. H owe ver, it ca n be argued that this technique is actua lly mo re me aningful i n ter ms of the
actual liste ni ng e xperi ence. I've me asured se ver al spea ke rs this wa y, and the results inva ria bly show ve ry go od cor re latio n betwee n
the mea sure d and the subje cti vel y per ceiv ed frequency bal ance o f a spe ci fic loudspeak er. While the bala nce is by no mea ns the only
importa nt factor in defining a spe ake r's per fo rmance, i t is a ver y si gnificant o ne. The i n- ro om bal ance of a give n spe ake r is li ke a
finger pri nt— distinct to that lo udspea ker, that roo m, and the sighting ther ein—a nd alway s say s much about the o ver all chara cte r of
the so nic presenta tion. W itho ut defining the i n-ro om bal ance, it's v er y easy to be "fo ol ed" by minor a no mali es tha t can make the
spea ke r so und a rtificial ly attra cti ve (o r una ttractive ). Once the roo m r espo nse is pro pe rly defined, it become s much ea sier to di g
be low the surfa ce to disco ver the under lyi ng quali ties – it take s a bi t o f effo rt to de te rmine the be st me asur ing po si tion tha t le ts y ou
“see ” the speak er a nd no t the ro om, but its wo rth i t! The bump ce ntred a round 850H z must be due to some r eflectio ns be ca use ne ar
field me asurem ents di dn’t show this emphasis in the midra nge ; a lso it wa sn’t audible whe n pl ayi ng a ll types o f musi c. The dro p above
15kHz is due to the limita tions o f my mea sur ement sy ste m.
NOTE: This de sign is strictly for the home DIY enthusia st and not to be used professiona lly without my pe rmission!
Tony Gee , The Ne therl ands
April 2006