|SEAS T14RCY/P-H + ScanSpeak
Copyright 2010 © Troels Gravesen
midbass: In a commercial speaker the transparent XP cone
has been fitted into a new EXCEL chassis with a copper
phase plug and copper plated magnet parts.
Available for the diy-community is the SEAS T14RCY/P-H driver of more ordinary parts. Except for possibly higher voice coil inductance, this driver may provide much of the same qualities as the OEM driver used in the commercial speaker.
Crossover modified for the HIQUPHON OWI tweeter:
The overall frequency response from the T14RCY-P/H is not the most beautiful around. But the sound is much better than it appears from the graph above. The ear is highly sensitive to bumps, where dips can very hard to detect. The intrinsic dip at approx. 1.7 kHz from the T14 is derived from resonance in the rubber surround. It can be dampened by placing self-adhesive foam strips on the rubber close to the membrane, but the crossover then needs further fine-tuning, so better leave it here.
Above is seen predicted response from 7
liter vented cabinet and vent tuning of 65 Hz. Red = room
response with suggested placement of 80 cm above floor
level, 110 cm to rear wall and 180 cm to side walls, the
actual placement in my listening room.
T14/RCY-P/H + D2010/8513 revisited, September 2005
One of my friends needed a mini for his
home studio and I suggested the T14RCY+8513 having the XP
membrane material giving an ear-friendly midrange with
excellent transparency. The 8513 in this company is sweet
and gently, nowhere near how it performed with the
18W/8535 driver in the 2.5 Clone. The 8513 tweeter must
never be mated with an even slightly harsh midrange.
All ready for final assembly. Getting crossovers into small cabinets can be a real problem and make very much sure that the crossover plate can enter the midbass hole before you glue the coils and capacitors in place.
The 8513 needs further attenuation compared to the OWI tweeter and I found 8R2 to balance well with the midband. The notch filter for the bass was changed slightly based on listening to white noise while changing the values of C, R and L combined with measuring the frequency response. The coil in the tweeter section was also changed to a standard value by adding a 1R0 in series with the 6.8 uF capacitor in the low-pass section. Not a big deal, but many do not have the possibility of un-winding a coil from 0.27 mH to 0.25 mH and sometimes it makes a difference, which it does here as the coil is the key component that determines the point of crossover for the tweeter.
I was positively surprised when I fired up this speaker again. This T14 driver is indeed a very good driver despite some rubber surround resonances at 1.5 kHz. Soundstage is wide and transparent and bass performance better than you would expect from such a small speaker. Well recommended for all kinds of music.
Comments from "tatxo" in Spain:
Mail #1: Not a question, just lots
of deep congratulations about your web page, and
thank you about your work offered to the comunity!!
Mail #2: I've opened the boxes again (both) for check the filter. First I discovered one big coil moved so I tried to put the spirals again to its place, quite hard. I compared both boxes and it seems to sound equal. I can't check the value of the coils, but the caps of 4,7 and 6,8 (picture of the filter in your web page) was replaced by 5,0uF. Rest of coils and resistors are ok. Sometimes I think I should to remake the filter completely, but it's expensive and the components of the clones seem to be good quality (Bennic). I've observed too a black-red hard wire to the midwoofer instead the other thicker and more isolated wires for the tweeter and the terminals. What do you think it's happening for that too much brillant sound? Should I replace all the coils because I don't know their value, the wrong caps, or just to apply more attenuation to the tweeter according to my ears? I haven't got measurement equipe.
Mail #3: At last I've discovered an inverted polarity in one tweeter, doing a serius dip in the crossover point in one loudspeaker, so the overall tonal balance was wrong and more attenuation was doing something, but little. I've never listened a original proac response so I never thought in such a error (I'm not a DIY expert). Well, I will investigate the correct atenuation for the tweeter soon, thought a 2R7 (taken of your webpage) or a 3R3 will be probably enough.