Any suggestions on an OW I, mdm 55 and 2 Vifa XG 18 plan very welcome

[leifislive]

Hi,

I am drawing plans on a <1000$ (speakers only) 3 way digital active project.
I would like to request some advice, comments and suggestions concerning drivers, design and possible errors...

My thoughts focused on the following drivers; they are in the desired range of price and I could find some data on measurements as well:

- Hiquphon OW I (or II or III)
- MDM 55
- 2 Vifa XG 18, yet more or less undecided presently (Usher 8945 seems to be good as well, but any smaller or larger driver might fit as well - would appreciate any comment on that point very very much)


My idea is to xover the mdm 55 as low as possible to reduce any impact of the bass enclosure on lowmidrange. However I can't find reliable data on distortion measurements at xmax; mechanical limit should be around 450Hz.
It would be most helpful to have some experienced advice on this point.

some more short information:

- design is a sealed box and size is preferably to fit perfectly in any room...
- xover is thought to be 4th order (preferable 500 and 3000)
- distortion (3rd and higher) should be kept at any frequency < 1% at 100 dB, 2nd order at least < 3%
- listening volume is typically < 90dB,

- good (NOT analytic) resolution is a desired goal (my reference in regards to resolution would be for example AKG 240 headphones)
- music is "broad spectrum" (mainly classical, jazz, electronics and alternative), yet both bad and good records of classical music should sound acceptable "natural"
- since I play a string instrument, natural strings sound is a main design goal

- upgrade to a 4 way system with an additional bass woofer is a future plan (xover around 80-100 Hz)

my present system is a vifa plw 18 and vifa xt ringradiator, which sounds good, but lacks the desired details and "natural" sound in higher midrange frequencies at higher volumes (it "cries" a little).

any suggestion, comment or internet/forum link on the speaker choices as well as on the lowest mdm 55 xover point would be most helpful.

Thank you very much for any of your thoughts on my problems, it just makes one feel more comfortable, if somebody comments on it before money is wasted...


regards and again thanks

leif

[sreten]

Hi,

Crosssover at 500 Hz is likely to be right in the middle of
the baffle step transition, which will complicate matters.

sreten.

[leifislive]

Hi sreten,

Thank you for your comment, I know, although I have to admit I didn't spend a lot of thoughts on that point.
but I will have to deal with this kind of problem anyway, or wouldn't I...

some possibilities I am aware of:

- I can "damp" the box from the exterior with some heavy textiles (carpet should be cheap and working, some wool (pullovers...)textiles hidden under a nice black textile), which should reduce diffraction relatively good as a side effect, no problem to me from an aesthetic point of view
- I can optimize the shape of the box and the location of the drivers, so that baffle step and diffraction do not add to the worst, since I do not necessarily need a slim tower...
- To really compensate the sole baffle step, I can use the digital eq features of these digital xo, should be working as far as I have a clue on these machines to minimize the bafflestep effects


After all, there seems to be a long on going discussion whether at all and to what extent it is really necessary to linearize the bafflestep in order to improve sound quality in a standard living room...

would you be more happy with a 1k crossover point? What would be your suggestion?

thanks for your answer

leif

[J2JD]

Lowest on the MDM 55 should be 700, 800 is good tho. I know there has been several designs using the MDM 55 HERE Theres not much left in the archives but try a search, you might find some info. That sounds like a nice project. Good luck with it. Also... http://www.selahaudio.com/rc3r.html

[ucla88]

I really haven't had the time to fuly evaluate the mdt55, but you can look at some of my distortion graphs here

Just click on the morel graphs one at a time. They are SL style distortion plots. A bit difficult to compare in isolation (I'm working on a midrange comparison-it will be a while)

I also have a not quite finished ML TL with the ow2, mdt55, and an SS8554.


I would not cross the mdt under 750, but really it seems to want to be crossed at 900+. If you're going to cross to 7"s, I agree that you should cross at 900-1k or so. If you have room, consider and 8 or pair of 8"s.

For a bit of intro on these distortion measurements, go here

It also helps to model the effect of your baffle on the drivers' response-download the BDS (Baffle diffraction simulator.) Just google for BDS or PV consultants.

[Paul W]

I seriously considered the MDM55 with OW1 in my system, but ended up using D76's instead (mine have to play HT loud in a very large room). Depending on slope and how hard you need to push the system, I think somewhere around 900-1k xo for the 55. The OW1 works extremely well with a mid-dome so you'll probably be very happy with the combo.

4-way dipoles

[leifislive]

To all, a big thank you for all your rapid responses.
On the FRD is a baffle diffraction simulator, as far as I know, I plan to use it for the optimization process.

@ucla88

Thanks for all the measurement you have had done, your graphs are exactly what I am looking for. Looks like you had basically the same idea as I had, nice to hear!

According to your data, 750 Hz would be fine with me, so 8'' would possibly work as well (I consider the beaming at 750Hz of an 8'' to be more or less irrelevant).
Unfortunately, Vifa doesn't have an 8'' in the XT or XG line, I will have to do some more research...

Usher 8317 ( I think that is the correct number) shows some respectable results in a recent published 8'' speaker test in a German magazine, may be it is an option, although it doesn't have a raised spider.

Do you have any "bargain" suggestion?

Again, thanks for you answer


@ Paul W


I have thought about 3 inches for along time, yet hard to find. If I had unlimited money, I would have taken the ATC, no doubt, yet life is usually about compromises...

There is an Usher 3 inch dome ( and an Accuton and a vifa one as well), but I didn't find any published "hard" data on it, do you know anything about it?

My room is not large, I once calibrated my system to 90 dB, which was pretty loud in my ears, so I think, I don not necessarily need a 3''.
As well, for natural string sound reproduction, I have changed my opinion yesterday while attending a concert, that 1000 to 6000 Hz are most important to optimize, something a 2 inch should be capable contrary to a 7'', even at 100 dB...

Thanks


Leif

[herm]

I have a pair of those Vifa XG woofers running in a vented box,
with an active cross. This is not my normal setup, just something
I have been playing with. Somewhere around 35 liters.

I use it up to 250 hz now (crossed to a PHL 1340) and I like their
sound. They go fairly deep, too. Last I checked they were only
$65 US at Parts Express, which is a pretty good deal in my opinion.

I expect to use them sealed, and add a 15" to each side for low
bass in the future (JBL Sub1500s).

[ratman542]

I played with the MDM-55's for a while but found them to be overly "present" in the mids on some vocals.

I much prefer my $34 (ea) pioneer 8's over the morel 55's as far as midrange is concerned, simply because of the smoothness of the midrange they produce. While not as well defined as the morel 55's, the pioneers reproduce a wonderfully smooth midrange.

However, -if you like strings (like you mentioned), the MDM-55's will really knock your socks off. To me they seemed to be very defined (even if a little on the bright side) on acoustic strings. In my opinion, the only negative thought on the 55 that I can come up with is an overly bright midrange on some vocals. Just like everything though, there are always tradeoffs. As for reproduction of strings? -I have never heard anything yet that was as defined as the morel 55's were. (my opinion of course).

One of the other reasons I went back to using my 8's for mids is because one of the MDM-55's failed (coil went open). I'm not sure how or why this happened, -probably just a defective unit would be my guess. They were actively crossed and kept well within their freq. range. I called morel on this issue, but they refused to replace it, -so take that for whatever it's worth. I love their products (in fact I'm still using the MDT-33's for the top-end of my system), but I would have doubts as far as their level of support goes.

So in other words, I have one that works and one that doesn't. If you want one to play with, I have one.

Rich.

[Euphase]

Originally posted by leifislive

Usher 8317 ( I think that is the correct number) shows some respectable results in a recent published 8'' speaker test in a German magazine, may be it is an option, although it doesn't have a raised spider.

I have shortly tried Usher 8137. Other than the cone color, for your application I would use them anyday vs Vifa XT/XG, or even Usher 7" 8945. I am not 100% sure, but I think Usher further improved the motor design on that unit later. I have no experience with Vifa XT/XG but from what I read, bass is not their strong area.

Originally posted by leifislive

There is an Usher 3 inch dome ( and an Accuton and a vifa one as well), but I didn't find any published "hard" data on it, do you know anything about it?

AFAIK Usher is a 2 inch dome like MDM-55.

If you are looking to keep price down, I would also suggest to look at XT19 instead Hiquphon OWI. I haven't had yet much time to evaluate the XT19, but it is a nice unit with copper Faraday ring etc.