Zaph said:
Note that I was suggesting the WR125ST, which has 16-ohm impedance (otherwise pretty much the same as the WR125S).
As you stated in the test, "any one could suit you depending on your needs and preferences". I like the CSS drivers because of the smooth top end. I prefer gradual slopes and I hate notch filters; they suck the life out of the music. Also the WR125 has twice the Xmax of the other drivers in the test, which should reduce compression at higher levels. That would be useful given the low XO frequency to the side-mounted woofer.
The price point of the RS125 makes it look appealing when buying a set of 8.
For sure! OTOH 4 mids/side create a compromise with center-to-center distances and lobing. Two WR125ST's/side would give superior FR and not give up much, if anything, in the way of dynamics. A bit more distortion of course, but you can't have everything. 😉
Anyway, that's my 2-cents. I felt it was important to let you know, because I already have four WR125ST's. 😀
A full passive dipole would be a big challenge to pull off.
What about designing it to accomodate active or passive? There's a lot of interest in dipoles, and not many designs.
audiobomber said:
I have to disagree with you about notch filters sucking the life out of music. (unless of course if they are poorly designed) OTOH, this place would probably be boring if everyone sat around and agreed on everything. 🙂 I do like shallow slope crossovers myself, but I often find myself willing to trade 2nd order slopes for 4th order when I gain the accuracy that metal cones give me. It's all personal preference. The dipole I'm working on will use a paper cone mid and shallow slopes. I'm not ready to get into that yet, but the usage of the mid embodies a different concept in dipoles.
Note that I'm looking for 8 ohm woofers in the MMTMM. the 4 woofers per side will effectively be wired series-parallel for a net impedence of 8 ohms.
Actually, the way I'm doing this MMTMM, it will have zero lobing and be a complete point source. I mentioned before it will be a 2.5 way configuration. The outside woofers will begin rolling off around 250 hz. At 250hz, all 4 drivers will be in operation and the effective center to center distance will be the points between each pair of woofers to the same point on the other side of the tweeter. At 2000 hz however, only the inside set of woofers will be in operation. Considering the small woofers, the center to center for the inside woofers will be small. Then, depending on the capabilities of the tweeter I pick, If I cross over low enough, what we have is a MMTMM with no lobing.
Look at it this way: If I were to use four 4" woofers, the effective woofer height is 8". But, you don't count the outside woofers if they roll off early enough, as they would in a 2.5 way. If I were for example to just wire the all the woofers together and cross over the MMTMM as a standard 2-way, lobing would be terrible and far worse than an MTM.
That's pretty much what i like about the MMTMM format wired as a 2.5 way. You get a slim profile from small woofers, there's no lobing, but you get the lower distortion from using multiple woofers to reduce Xmax. And it looks cool. 😀
Zaph said:
Oops, I missed that. I look forward to hearing about it.
Glad to hear you still intend to do a dipole.
Can someone tell me why a tall slim MMTMM is of such interest? In particular, why would this be better than a WMTMW or an MTMWW? In other words why a 2.5-way instead of a 3-way? Is it just that the slimmer cabinet shape is preferred, or is there some other reason?
Yes, the main goal was a super-slim cabinet. The next goal was a low budget. Finally, the goal was to get better sound quality than the "home theater in a box" speakers you see in Best Buy. Sure, they're small and look like tiny slivers of modern art- but where's the sound?
Due to budgetary constraints and impatience, I think I'll be changing my approach to my next project and will make something with the Pioneer B20FU20-51FW 8" full-range. This has been described by Nelson Pass and others as being fairly listenable and extremely cheap. Since I already have a Hafler DH-500 amplifier, I think I'll try some of the current-source tricks as described at PassDIY
I'll be compromising a lot on cabinet size, but this time "cheap" wins. I'll be watching this project with a lot of interest. Good luck.
Due to budgetary constraints and impatience, I think I'll be changing my approach to my next project and will make something with the Pioneer B20FU20-51FW 8" full-range. This has been described by Nelson Pass and others as being fairly listenable and extremely cheap. Since I already have a Hafler DH-500 amplifier, I think I'll try some of the current-source tricks as described at PassDIY
I'll be compromising a lot on cabinet size, but this time "cheap" wins. I'll be watching this project with a lot of interest. Good luck.
audiobomber said:
Huge speakers that dominate listening rooms are becoming a thing of the past. As Joe suggested, it's obvious what people want by taking a walk through a Best Buy superstore. They have a big selection of "sound sticks" which look like modern art but sound terrible. I guess the main goal for the MMTMM would be to accomplish the same small footprint and sleek looks but take a large step up in sound quality.
The MMTMM format can be wired to reach an 8 ohm net load, which is generally a plus compared to the MTM format. 16 ohm woofers are rare. But I'd have to say that generally, people just want slim. A single 6" woofer can easily have more output than four 3" woofers. No benefit there.
What's been bugging me lately is that there's a mindset among the snobbish audiophile crowd That looks don't count for anything, it's just the sound quality that matters. Personally, I want it all. It will be rare if there's another time in the future when I allow a big ugly set of "monkey coffins" in my living room. (unless they somehow make an artistic statement) Likewise, I'll never allow a set of Bose cubes in my living room either because sound quality is still important to me.
Zaph said:
I agree, looks are important, as long as the sound isn't compromised.
What concerns be about an MMTMM is the height of the speaker to get the tweeter up to ear level. And it really bugs me that very few tweeters have trimmed faceplates to get them closer to the mids, which means a lower HF XO to the tweeter.
This thread is just what I need. My 4x B3s idea got pulled apart on the full range forum, MMTMM with outers rolled of early was the suggestion.
So I'll be eager to copy the tweeter choice and crossover that gets designed here, assuming the b3s gets used.
I'm looking to active cross/bi amp to stereo subs in separate enclosures (subs almost finished, amps next).
So I'll be eager to copy the tweeter choice and crossover that gets designed here, assuming the b3s gets used.
I'm looking to active cross/bi amp to stereo subs in separate enclosures (subs almost finished, amps next).
jimbo1968 said:
Higher quality would probably be a woofer anywhere between $20 and $40. If I were to go with something a bit more expensive, I'm leaning towards either the Aura NS3 or the Dayton RS125. They are both right around the $20 ea range. The main benefit is deeper response and more output in a slim package.
Disabled Account
Joined 2003
John,
Between the NS3 and RS125, my vote goes the RS125, simply for the 3dB sensitivity advantage.
The speaker is one with LOTS of drivers, so IMHO it should live up to the expections by being able to play LOUD. 🙂
On the other hand, it costs twice as much, and probably needs a more complicated filter, and shipping from Parts Express is a real pain for me too. 😉
Do you plan to design for right-against-the wall placement? 12" is fairly deep for such a narrow cabinet...
Between the NS3 and RS125, my vote goes the RS125, simply for the 3dB sensitivity advantage.
The speaker is one with LOTS of drivers, so IMHO it should live up to the expections by being able to play LOUD. 🙂
On the other hand, it costs twice as much, and probably needs a more complicated filter, and shipping from Parts Express is a real pain for me too. 😉
Do you plan to design for right-against-the wall placement? 12" is fairly deep for such a narrow cabinet...
tktran said:
I think sensitivity is over-rated as a valuable specification, particularly with small drivers that will be Xmax limited in use. In my opinion there's no magic that happens with high efficiency drivers. If people are after loudness, the way to do it is with a big amp and speakers that can handle some dynamics without immediately going past Xmax. (that leaves out Fostex) High efficiency speakers have their place with those who use tube amps or public address systems, but that's it. I kind of sound like a hypocrite, since I have a web page titled "Woofers with lower Xmax sound better" but that's in relation to monster subwoofers, which is a different issue.
The NS3 vs the RS125: I'm leaning towards the NS3 for a few reasons. It has more output capability, it has lower bass distortion, and it's frame is 1.5" smaller, which lets me keep the cabinet slim. The NS3 has smoother response in the midrange, and there is no problem getting a true 2nd order crossover slope out of it.
The NS3 only has one negative, and that's it's flimsy stamped frame. I typically have to glue them in place in addition to screwing them to avoid rattling.
Since the design is a 2.5 way, it's intrinsic BSC makes this design strickly for an away-from-the-wall installation
Disabled Account
Joined 2003
Hi John,
I see where you're coming from, particularly when the NS3 has all the other advantages (slimmer cabinet, smoother midrange response) but what I can't get my head around is this:
Why then, do speakers like your XG18/TDFC/XG18 MTM sound more dynamic and lively (I can't remember how you put in exactly, but I've got a quote somewhere in my Inbox 😀 ) than your L18/TBFCG?
If you made an MMT with the L18/TBFCG would that not also sound more dynamic and lively than the MT?
I thought this was primarily a function of sensitivity.
What about possible non-linearities of sending twice as much power to the speakers to make up for the 3dB loss in sensitivity.
tktran said:
Yes, I might describe my XG18 MTM as dynamic and lively. But I also might describe it as slightly forward and bright. Some of this can be attributed to the differences between the tweeters, but I think most of it is due to the differences in radiation patterns and power response between the MTM and TM format. MTM's have a distinct sound due to their radiation pattern, and the larger the MTM, the more audible it is. Some people like and prefer this type of sound, as it might be described as more exciting.
Anytime excursion is reduced, distortion goes down, which is one of the main benefits of multiple driver systems. Two XG18's are definitely better than one. With the NS3 vs the RS125 however, you have to look at the whole picture though - which is basically the distortion heard at a given output level, independent of sensitivity. A smaller woofer may need more excursion and power to reach a certain ouput level, but it still may have lower distortion at that output level. That's the case with the NS3. It's low end distortion is substantially better than the RS125's. This is even more true if you consider that it has a higher relative bass level due to it's higher Qts. If the RS125's were equalized to match the 100hz bass level of the NS3, 3rd order harmonic distortion at 100hz would be unbearable.
Then there's all these other issues, such as compression at high levels and where the subwoofer crossover will be. The considerations for selecting a driver are almost endless. It's amazing that anyone can even make a descision at all. I'm still torn, since PE gives an additional discount for ordering 8 drivers. (Their website only lists 4+ qty discounts but there are more levels above that) If I went with the RS125, I would have to cross the subs over higher, make the cabinets wider, and do LR4 instead of LR2. I don't know if it's worth it.
I'm equally interested in doing a larger MMTMM with 5" woofers. Perhaps L15's and a TBFGC in the the middle. That would be a seriously low distortion and very dynamic system. It's almost half way to line array. But it would also be huge and expensive. The polls say people want nice drivers in a slim cabinet though, so I intend to do that first. So many options, so little time.
Disabled Account
Joined 2003
Ok this makes sense.
This would make a great woodworking project. I like building speaker cabinets, and after building 3 speakers, all the same kind of 1meter tall floorstand/veneered two-ways, I'm ready to try something new.
+ the NS3 are great value aren't they? And because they're light, shipping from the US is very affordable too... 😉
If you were to do an MMTMM with 5" drivers, do the outer woofers have to be the same as the inner? The MCA15RCY pure mid measures pretty well in Mark K's tests...
Zaph said:
best place for the 0.5 woofers is on the back of the cabinet, where the 90 degree phase roll will be in the shadow of the cabinet -- if on the front, they will be moving out of phase with the Ms running all the way up. And above that roll-off point the impedance will move towards 4 ohms as the 0.5 woofers/filter mpedance starts climbing.
I've been using the NS3s of late, they are really nice. They have the big advantage of no filter required (i find the filters most often subtract more than they add -- even if spot on design wise)
dave
tktran said:
The problem with using a different .5 woofer is that the smaller full range woofer will always run out of xmax first. It's been done before in some designs but I generally don't recommend it. I'm sure the MCA15RCY would make a nice WMTMW though.
planet10 said:
Last time I tried the .5 woofer on the back, it didn't work out well for me. I can't pinpoint for sure what it was, but the lower midrange/upper midbass anechoic response curve was terrible, and then it got worse in the room. (at least worse than a normal terrible room response is) I tried several things, including running it full range, and various BSC corner frequencies, but eventually I rebuilt the thing as a normal TMM and it sounded much better. (this was a Silver Flute W14 system) I suspect the rear woofer was sending too much midrange information to the rear wall to be reflected back.
Are you doing anything special with a rear firing woofer? How far out from the back wall is required to get good sound?
Zaph said:
I'm typically running the back drivers FR. The closeest a speaker can get to my back wall is a couple feet, for critical listening they come out more (for the diyFest we just had 4-5 feet)
Running them on the back brings the room into the equation even more than usual, but i find it hard to get the mid transition point to sound right with them on the front.
dave
What about some NS3's and a Daline?
I'm convinced that those slim Yamaha towers in the Best Buy are using a double-chamber reflex enclosure, with one of the tuning points even lower to eke out the last little bit of response from those drivers. It's fascinating, and works surprisingly well for extending the bass, but that's about it. The bass still sounds sloppy and boomy from those tiny drivers as they are setting up their resonances in those ports.
I'm convinced that those slim Yamaha towers in the Best Buy are using a double-chamber reflex enclosure, with one of the tuning points even lower to eke out the last little bit of response from those drivers. It's fascinating, and works surprisingly well for extending the bass, but that's about it. The bass still sounds sloppy and boomy from those tiny drivers as they are setting up their resonances in those ports.
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