Seas FROY MK3 cabinet with W15CH001 and Hiquphon OWI?

[Guijs]

Hello,

I'm planning to build a center speaker with a pair of Seas W15CH001 drivers and a Hiquphon OWI tweeter. My main speakers are a David Ellis 1801b bookshelf that use Seas W18 and Hiquphon OWI.

Seas have the FROY MK3 kit that use the W15CY driver and T25CF002 tweeter.

Is it possible to use the FROY MK3 cabinet and crossover with W15CH (Neodymium magnet) with the Hiquphon OWI tweeter as a drop in replacement? The SEAS drivers frequency response are very similar and both tweeters are 25mm soft dome, although the Seas tweeter is 89db and the Hiquphon OWI is 87db.

Any chance this will work?

 

[Face]

Nope, their impedance curves are different as well.

 

[system7]

These two W15 woofers are almost identical. But the OWI is not as robust as the SEAS T25 tweeter, and I think you'll need a higher crossover point.

This Troels' 3kHz circuit seems a good point of departure.
W15CY001-OWI.

The breakup notch is going to be unchanged around 8-9kHz. The tweeter filter will probably become 3.3uF/0.27mH/10uF with less attenuation for 6dB gain on the parallel woofers. Or you wire the woofers in series, and regardless just do the doubling and halving thing on the bass crossover values which leaves the tweeter circuit unchanged.

 

[system7]

I just had a play with the FROY Mk3 circuit. Best I could do was raise the crossover to 2.5kHz and keep things tidy. We'll need to lose some 2dB attenuation IMO too.
FROY MK3

So the below works well enough, IMO. The 0.1R is just a marker for adjusting tweeter level. 1R is 1dB usually. 2R is 2dB etc. Use preferred values IMO. 2.2 or 2.0 won't make any difference.

 

[Guijs]

I just had a play with the FROY Mk3 circuit. Best I could do was raise the crossover to 2.5kHz and keep things tidy. We'll need to lose some 2dB attenuation IMO too.
FROY MK3

So the below works well enough, IMO. The 0.1R is just a marker for adjusting tweeter level. 1R is 1dB usually. 2R is 2dB etc. Use preferred values IMO. 2.2 or 2.0 won't make any difference.

Thanks system7!

I have contacted SEAS and they told me I can use the W15CH in the FROY MK3 instead of the W15CY without any modifications. I also ordered a LEAP crossover design from Madisound, but they only do it with the SEAS T25 Tweeter.

Your approach seems very good. The crossover point of the Hiquphon OWI in the David Ellis 1801b is also at 2.5kHz and losing 2db attenuation must keep all drivers at the same level.

The fact that I will use the speaker horizontally will require any modifications at the crossover?

 

[sreten]

Hi,

See Zaph|Audio - ZA5 Speaker Designs with ZA14W08 woofer and Vifa DQ25SC16-04 tweeter
and Zaph|Audio - ZDT3.5
for the differences in x/o's for the center channel.

rgds, sreten.

 

[system7]

Guijs, I really don't see why you shouldn't uses the modded MTM SEAS FROY circuit!

http://www.seas.no/index.php?option=com_content&view=article&id=385:froy-mk3-seas-diy-kits&catid=66&Itemid=365

I've done just tiny things to it, so it is true to the original idea. X/O at maybe 2.5kHz, 2 dB less tweeter attenuation.

I really don't see anything wrong with it. Even Troels' ideas weren't much different. Beyond a certain point, you are just fiddling about. If SEAS have done the design right, then the modded 2.5kHz circuit will sound essentially the same. These are tiny differences.

 

[Guijs]

Guijs, I really don't see why you shouldn't uses the modded MTM SEAS FROY circuit!

FROY MK3

I've done just tiny things to it, so it is true to the original idea. X/O at maybe 2.5kHz, 2 dB less tweeter attenuation.

I really don't see anything wrong with it. Even Troels' ideas weren't much different. Beyond a certain point, you are just fiddling about. If SEAS have done the design right, then the modded 2.5kHz circuit will sound essentially the same. These are tiny differences.

Hi Steve, the 0,1 ohm at the beginning of the tweeter circuit is correct or did you mean 1,0 ohm?

 

[system7]

The 0.1R is a marker for where the tweeter level adjustment goes. You set that by ear. Every ohm adds one dB attenuation. So 3.3 ohm cuts level 3dB, or half power. Tweeter level is quite sensitive so I keep a stock of them

3W are fine for 1 or 2.2R. Maybe 7 or 10W for higher values which will run hotter. A 6 ohm tweeter will never exceed 10 or 20W, so do the math.

And anyway, if the resistor blows in that position, it just acts as a fuse, which is good design. lol

But my guess is you should start with a bit of 20A tinned copper wire in that position, aka fuse wire, and level won't be far wrong.

 

[Guijs]

Understood, thanks!

EDIT: If we have two woofers of 85db sensivity each, can I expect that the db level will be higher and perhaps will be quite close of the 87db from the tweeter?

 

[system7]

Those E0015-08S W15CY001 woofers give about 81dB at 100Hz. Add 6dB for MTM twin driver reinforcement on-axis and you're up around 87dB which matches either 88-89dB tweeter, well, just about. FWIW, the overly deep notch isn't right for the less peaky woofers I am using here, but we're trusting SEAS, eh? It gives the general idea.

Sensitivity is difficult with woofers, but the 500Hz measurement is usually about right by the time you have got it flat. SEAS do measure in a typical cabinet.

Bottom line is the tweeter has enough level for all eventualities here, but you always set it by ear anyway. Partly a matter of taste.

 

[ckwong99]

Hi System 7 . Why u modify Froy mk3 xover point to 2k4. What the sound changed and what is MIO ?
I want to follow seas original make it but i am so interest why u would modify

 

[system7]

The original question was about using two slightly different SEAS woofers with a Hiquphon OWI tweeter. And base it on the Froy III design:
FROY MK3

The neodymium woofers were actually almost identical to the Froy woofers. So no problem there.

But the 19mm Hiquphon OWI is not so loud, and more fragile. Troels used a 3kHz crossover with the W15C001 and an OWI.
W15CY001-OWI

So we modded the crossover slightly for a higher crossover frequency. All a bit of guesswork, but ought to work. It wouldn't have been hard to adapt the whole Troels design to an MTM too. But whatever works! 🙂

 

[ckwong99]

Thanks 7.
So if i use same driver of the original. Then i no need to follow this modified xover version . am i correct ?

 

[system7]

Yes. Of course.

This thread was a look at what you do if you use slightly different tweeter in Froy design. A Hiquphon OWI.

FROY MK3

The SEAS design is for the Millenium tweeter.