A fistful of Monacor SP-200X

[Mikael Abdellah]

I got an urge to build a crazy box with fullrange-drivers since I have never fiddled around with any. Since I work at Monacor, it's quite economical for me to use monacor drivers.

The project I had in mind was a big box with 6pcs of SP-200X (8inch fullrange speaker). When I simulate in winisd I get unusual (for "normal" drivers anyway) results. It seems I need a HUUUGE box to make them go low. Also I have a "bump" on the line which I would like to get rid of without a 680liter box (that size actually makes lovely similations). Is the "bump" just a simulation error or is this common for some fullrange speakers?

If a 600 liter box is what it takes then 600 liters it is, but I would like a smaller box if it's possible.

 

[Cordraconis]

I quickly modelled a maximally flat vented box with one SPH-200x driver in it.

83 liters is one big mother f... for ONE fullranger !!!
40Hz as F3 is jummy, but still ...

It seems your sims are correct, but may I suggest using SPH-60X ? I designed a vented enclosure of about 11 liters, with a F3 of 60Hz for a friend of mine. 60Hz is lower than you would expect for such a small driver, but you could get to 50Hz in a 25 liter enclosure, which *wouldn't* give you the "almost there but not just yet."-feeling about the bass.

There is a pic here:
http://users.telenet.be/Hellhouse/CesT_and_Ambiorix-driver.jpg

The woofer in front is a SPH-212, which I will use in my Ambiorix sub (flat till 30Hz, vb 74L, total of 109L) in a few days.
The combination of those schould be very cost-effective.

 

[giulio]

Hi,

something is likely to be very wrong with your simulations. I have used them open baffle with great satisfaction.

I doubt you need that kind of box.

Giulio

 

[Mikael Abdellah]

Thank you both for your ideas. I was leaning towards the 8 inch because of its much larger area. This speaker will have to provide a lot of SPL. I was planning to run the 6 speakers in series and then connect them to a 100V amplifier which is specified 100V @ 42Ohm. I know it's a totally braindead idea, but that's just the way I am

 

[joensd]

A speaker with multiple 8" ?
Unless you roll 5 of them off at high frequencies I don´t think you´ll get satisfactory results.
What about one driver as a start or a bi-pole transmission line?

Any comparisons of that especial driver with more "known" chassis?
Looks tempting as it is quite cheap.

greets
Jens

 

[Mikael Abdellah]

Excellent point. That totally slipped my mind. Hmmm... guess I will have to figure out something else. I was a nice idea though

 

[Igla]

I've put my Monacors SP-200X in a 75 liter bass-reflex cabinets
(one driver per box) and they are doing just fine.I drive them with LM3875 gainclone and NON-OS TDA1543 DAC.Bass is low, fast and defined.

Regards,
Igla

 

[Mikael Abdellah]

I have ordered a pair of them for test. They will reside in a fairly large box of 80 liter tuned to about 40Hz. I have tried the best I can to model a suitable parallel noth filter and a Zobel circuit for it. I used the formulas found at carstereo.com It should be quite interesting since I have never heard a full-range single driver speaker.

 

[sumacSK]

Hi,

I also use this driver in 47 litre box tuned to 45 Hz and I'm very happy with it. Looking forward to your experiences. BTW this driver needs helper tweeter IMO (I use eminence APT80 crossed with 0.5uF )

Good luck Martin

 

[Mikael Abdellah]

Finished the speakers yesterday. You are right about the tweeter. Too much moving mass for high dynamics.

First I tested them with just the zobel circuit. The sound was very "middy". This is of partly because they are not "played in" yet. They will sound better after a couple of hours.

Today I assembled the parallel notch filter. Now we're talkin'! Much better. Except the lack of extreme highs they are quite OK. Considering the cost, they are excellent. Maybe I should try the smaller 5" drivers too some day.

 

[joensd]

Maybe I should try the smaller 5" drivers too some day.

One really nice "cheap trick" is the CT193 from Klang+Ton:
http://www.lautsprechershop.de/hifi/index.htm?/hifi/ct193.htm
Monacor SPH-60X in a little BR. Amazing bang for the buck.
Got the plans somewhere and the notch is given in the link.

greets

 

[Cordraconis]

Monacor SPH-60X in a little BR. Amazing bang for the buck.
Got the plans somewhere and the notch is given in the link.

Amen!

But I didn't use a notch in my CesT's and I don't think the drivers needed it. What is it for? Bass extention in a smaller cabinet?

BTW, I still have 2 drivers lurking around, and i want to put them in smallish sattelite speakers to go with my sub. The sats must go flat till 80Hz, and i want to try something else than a BR, and closed doesn't get me further than 120Hz.
I'm now thinking about either a Backloaded Horn, TL or TQWL, whatever is smallest and/or gives least cone excursion for better SPL and/or least group delay for best imaging.
Do you have some ideas to point me in the right direction or should i really start a separate thread for this?

 

[joensd]

BTW, I still have 2 drivers lurking around, and i want to put them in smallish sattelite speakers to go with my sub. The sats must go flat till 80Hz, and i want to try something else than a BR, and closed doesn't get me further than 120Hz.

You want them as small as possible with 80Hz flat?
Modelling in WinISD shows you´d need at least 8liters to reach that.
In ~11l it goes almost flat til 60Hz.
I modeled it in Martin Kings worksheets as well but to take advantage of the TL you´d need a little floorstander of about 15l minimum.

greets

 

[Cordraconis]

You want them as small as possible with 80Hz flat?
Modelling in WinISD shows you´d need at least 8liters to reach that.
(...)
I modeled it in Martin Kings worksheets as well but to take advantage of the TL you´d need a little floorstander of about 15l minimum.

Well ... flat-ish.
With an F3 of 77Hz I can get away with 5.5 liter BR and a 1-1.5dB crest from 100-200Hz. A little bit like built-in baffle-step.

Thank you very much for MK's modeling! I haven't started to dig into TL's yet, but if I remember the rules of thumb, you start from Sd, and end with 1/2 Sd, so from 75 - 37cm^2 and 100cm long for 1/[email protected], gets me a volume of around 5,7liter.
Very much like a BR, so I should look for max SPL and groupdelay.
However, I read that a TL should be around Fs of the driver, so not around 80Hz ... Maybe you can help me out with that, since i'm not familiar with mathcad.
Any idea's or curves?

Hornresp gave a very nasty SPLcurve for a 100cm exponential(80Hz) backloadedhorn, starting from 37cm^2 till 670cm^2 mouth area. And i won't even start to calc how much liters that would be, evendough the cone displacement is exemplary till 80Hz.

 

[joensd]

I simuated with the ML-TL worksheet with the following parameters:
L=80cm (31.5in)
Z=0.36
SO/SL=2.4*Sd
rport=2cm
Lport=6cm
(No fold, no taper.)

Think of these values as starting point; haven´t played around too much. And of course keep in mind that the speaker will sit much too low for ear height.

greets

 

[Cordraconis]

I simuated with the ML-TL worksheet

Errrm ... thank you very much, but maybe I should explain a bit more with what i meant with 'not familair with mathcad'.

i don't have mathcad, so i can't use MK's worksheets, and since I never used it during my education, the free version i heard about wouldn't help me a lot either and just installing it for some sims and then unistalling it seems a bit of a hassle.

oh, I would go for a folded TL so it can be used as a bookshelf speaker, more exactly to put them next to my PC screen (glued magnets inside to make them shielded.)
Maybe by folding them i can minimize internal reflections and improve imaging. Too bad B&W's Nautilus -raindropshape doesn't seem appropriate here to fit it inside a rectangular cabinet.

If i understand enough of the specs you gave, the beginning of the (80cm) TL is 2.4*73cm^2, so 175cm^2, and the end is 2cm*6cm: 12cm^2. So the total volume would be around 7.5 liters.
Hmmmm

 

[joensd]

If i understand enough of the specs you gave, the beginning of the (80cm) TL is 2.4*73cm^2, so 175cm^2, and the end is 2cm*6cm: 12cm^2. So the total volume would be around 7.5 liters.

no taper.

The ML-TL is by the looks of it a BR.
Its 80cm high and has a cross-section-area of 2.4*Sd (I used Sd=80cm^2) so ~15.3l.
[IMGDEAD]http://img233.imageshack.us/img233/7572/clipboard2ac.th.jpg[/IMGDEAD]

Depending on your size restrictions you can choose different tunings of course but 5.5l is IMO on the low side and will probably leave you with a slight hump.
I´d use 8l minimum, 10.5l is what WinISD spits out and extended bass would be ~ 15l.

greets

 

[sumacSK]

Hi Mikael,

Yes you're right this driver is excelent for the money it costs... Could you share the network scheme? I would like to try it. Maybe it gets even better...

Thanks Martin

 

[Jean-Marc P]

Bonjour,

I use with satisfaction four SP200X in dipole configuration on open baffle. A current amplifier (no feedback, two stage, class A) extend bass frequency response with higher Qts. Not really more moving for same level because more emissive surface.

Multiples sources in correlation increase efficiency to 6dB in compensation of width dipole, so space between driver is lower wavelength (about 500hz).

Current mode extend so high frequency response, more voltage with increase of impedance coil, so no tweeter. Two driver on front, two driver on back, little interference of directivity lobe and aperiodic dipole.

http://perso.wanadoo.fr/jm.plantefeve/dipolex.html

Jean-Marc.

 

[Cordraconis]

The ML-TL is by the looks of it a BR.

Yeps, it seems only a BR will give me the smallest size for my F3 (and have the flattest responce!)

Using a TL or horn to get a small cab with a given F3, seems a bit like trying to get good mileage from a Hum-Vee jeep.
(Meaning it's designed for a totally other purpose!)

Thx for helping me get rid of the TL-idea. I'll start working on my BR design now, and stop hijacking this thread.

Bye