ShinOBIWAN said:
The Neo 3 pdr will provide some of that magic (like the RAAL), that isn't easily "seen". In this case its enclosure volume is fairly critical - other wise it becomes overdamped (if its to large), and you loose that magic (..and you might as well look at something like the Seas at that point).
Hmmm.....
This is one of those threads where the poster knows the names of
some good drivers and has no idea what he does not know about
speaker design but wants the "best".
FWIW electrical engineers generally (my degree) understand
some aspects of loudspeakers and generally next to nothing
about acoustics and physics and its applicability to good design.
The suggested process :
Is simply not the way to do it.
http://www.rjbaudio.com/Audiofiles/FRDtools.html
http://www.geocities.com/woove99/Spkrbldg/
http://www.troelsgravesen.dk/Diy_Loudspeaker_Projects.htm
http://www.humblehomemadehifi.com/
http://www.rjbaudio.com/projects.html
http://www.zaphaudio.com/
/sreten.
I really dislike any threads with "best" in the title, I usually ignore them.
This is one of those threads where the poster knows the names of
some good drivers and has no idea what he does not know about
speaker design but wants the "best".
FWIW electrical engineers generally (my degree) understand
some aspects of loudspeakers and generally next to nothing
about acoustics and physics and its applicability to good design.
The suggested process :
Is simply not the way to do it.
http://www.rjbaudio.com/Audiofiles/FRDtools.html
http://www.geocities.com/woove99/Spkrbldg/
http://www.troelsgravesen.dk/Diy_Loudspeaker_Projects.htm
http://www.humblehomemadehifi.com/
http://www.rjbaudio.com/projects.html
http://www.zaphaudio.com/
/sreten.I really dislike any threads with "best" in the title, I usually ignore them.
sreten said:
Exactly.
The real problem however is that it a re-occurring theme.
With the exception of naïveté with regard to bass extension vs. enclosure volume (sealed vs. vented), what he wants (the end result, NOT a sealed design and some boutique parts selection) is actually do-able at a reasonable price - but I don't know of such a design and I'm not sure there even is one.
Sadly it makes me want to do such a design, BUT I know that I neither have the time nor will I spend the cash on something that I know is no longer what *I* really want.
So the best I can do is offer up a fairly quick suggestion of what I think that person should do based on a guess that *belies* just how much knowledge goes behind that suggestion.
....
What I think is particularly ironic here is that Shin has questioned me on the selection of the Neo 3 pdr. (..don't mind the questioning, but I do appreciate the irony.
) It wasn't *that* long ago when he went through something not altogether dissimilar to this poster's dilemma. While he avoided many of the crossover issues by going digital, there were still many costly driver swaps that occurred - driver swaps well beyond the financial abilities of most DIY'ers.
For most people then in a similar situation it means buying these drivers and being stuck with them and no viable loudspeaker (..i.e. the "wanting everything and ending up with nothing").
And seemingly the pinnacle of this "diy driver bane" are the Seas EXCEL magnesium drivers.
Superbly designed,
Superb measurements,
Good looks,
Detailed sound,
..oh, and ultimately worthless for long term enjoyment (..funny how this just doesn't seem to get through
)-and so we go round and round again.
ShinOBIWAN said:
Can't argue with that.
Well, you can.. Hell, I might even.
But I've been putzing with my neo 8's getting a "feel" for them - presumably if they are anything like the neo 3's then my statement *should* hold.
(note that the overdamped nature actually works fairly well when they are in a dipole config. for some reason.)
(..though of course there are no absolutes and I ALWAYS reserve the right to be wrong.
)Because I thought it was a bit hinky with respect to volume - I went back and actually *looked* at the internal volume of that cabinet..
Net internal = 1/2 cubic foot.
At *that* point you might as well have a sealed system. Because with 2 drivers around 7 inches in diameter you are simply not going to get much bass near the reference level regardless of the design.
*IF* you actually had about a cubic foot internal, well then there would be something more to "play" with.
To get more bass look at the offerings in the 5-5.5 inch driver range, OR go back to the *non*-curved side panel box.
i.e THIS is the box that has 1 cubic foot internal:
http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=302-750
Net internal = 1/2 cubic foot.
At *that* point you might as well have a sealed system. Because with 2 drivers around 7 inches in diameter you are simply not going to get much bass near the reference level regardless of the design.
*IF* you actually had about a cubic foot internal, well then there would be something more to "play" with.
To get more bass look at the offerings in the 5-5.5 inch driver range, OR go back to the *non*-curved side panel box.
i.e THIS is the box that has 1 cubic foot internal:
http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=302-750
ScottG said:What I think is particularly ironic here is that Shin has questioned me on the selection of the Neo 3 pdr. (..don't mind the questioning, but I do appreciate the irony.
I questioned it out of the need for a tweeter that could cross low in a 2-way MTM. I tried such things with the LGT, running both the mids to 1.5Khz and all sorts of other frequencies. The depth of the soundstage and particularly the height just callopses the higher you go. I quickly went back to the original 0.5way on one of the mids.
So, to me, the 2Khz you suggested doesn't really do the job and 1.5Khz looks do-able with the Seas and with a fairly nice power response too.
Just in case your interested you read more info on DXT waveguides here:
http://www.dxt.dk/pages/webside.asp?articleGuid=35000&menuGuid=15288
They also do one off work for the more adventurous DIY'er.
Fun times. Think it was around three bass drivers before I was finally content. Some projects just work out like that, especially if you don't want to compromise much. If the individual drivers aren't working well together then eventually you have to swap something out. Sadly this can only really be done with real listening rather than modelling and can, as you pointed out, turn expensive. I expect I'll go through a similar situation in a future project, on the flip side the last design I built worked straight away - nothing to change.
BTW You never avoid crossover issues just by using digital. In fact that presents some different problems to consider. Any flaws in the loudspeaker design will still be apparent if the thing itself isn't thought through correctly. Digital does bring additional flexibility and speed to the crossover design process.
ShinOBIWAN said:
While I could be wrong, I don't think you would find that problem with the neo 3 pdr and the Ushers and a well "sorted out" crossover. (Note that it doesn't have to be 2 kHz - THAT was just what Dennis had applied for his "plop-in-the-box" part deux.) In particular the Ushers (excepting that resonance at 6+k that needs to be notched out), are not terribly extended. As such midbass combing should be low with an LR - 6db base lowpass. Moreover the neo drivers are strange beasties, lots of emmisive area and a small enclosure volume allows you the ability to cross at *oddly* low freq.s - so long as you can sum flat with the midbass drivers. Even 1.5 should be OK with these drivers - its just a matter of summing with the midbass then (..and excepting a certain loss in ultimate spl). (..the things the Neo 8 will do with a small chamber are just plain WEIRD.)
On the other hand though, no they certainly won't be the equal of the RAAL's (not even close).. but like any really good driver they should have that certain magical quality about them that isn't currently measurable/quantifiable.
I'd strongly disagree about avoiding issues with going digital on the crossover. Number one: complexity and learning. Being able to make all sorts of adjustments "on the fly" allows for so much more flexibility, speed, and ease of learning with respect to prototyping a given design. Its also a LOT less expensive (unless you hit upon something outstanding to begin with). Number two: a passive crossover is another resonant load on the amplifier - it will play a substantial role in the overall sound of the finished design without respect to its intended purpose.
..yeah, no date tonight -
(..its been my experience that dates on and around valentines day are just plain baaaaaaaddddd news, well maybe not initially - but they always end-up very bad.
)
ScottG said:
That's the problem, I don't have direct experience with that driver so its tough to know the quirks. On paper I wouldn't recommend that 1.5K cross using the Neo 3 but from what you say it might just work. The Seas seems an easy choice because its clear that its got output at that level and I'd imagine distortion to be good since its based on the well regarded 27/TBGFG. Probably will be more excursion limited at that crossover point rather than distortion limited. The loading from the wave guide will help slightly as well.
Yes you could argue that from an overall standpoint passive crossover require more knowledge. You need to understand what components values and circuit topology will get you the intended results. But that's still not enough because the intended results also need to be founded on good knowledge of accurately affecting the minimum phase behaviour of the individual drivers to form a coherent loudspeaker system - this is universal for either passive or digital crossovers. For digital systems you need not concern yourself with how the crossovers are made because they're sat right there as a programmed transfer function but you do need that other layer of design knowledge that's applicable to any crossover implementation. In other words its misleading to word it so that it appears to avoid crossover issue, I do now understand you meant its just an easier and quicker path rather than my mistake of thinking you were hinting that it allows to disregard established crossover pitfalls.
I'd say that digital active or any active system can cost more. The real cost is the extra number of amps required. The better digital crossovers also need investment in DACs and processing, this can amount to large sums of money - for example the DEQX at $3000 or a PC with high quality sound interface and suitable software for around the same amount.
I am wondering what you guys think of this design;
http://www.lonesaguaro.com/speakers/DaytonRS7/Cryolite.htm
I built a pair about a year ago and have been listening to them since. I like them quite a bit
but do feel the crossover probably needs more work.
The reason I am suggesting them is it seems the direction the thread was going and would
possibly satisfy the op's needs.
http://www.lonesaguaro.com/speakers/DaytonRS7/Cryolite.htm
I built a pair about a year ago and have been listening to them since. I like them quite a bit
but do feel the crossover probably needs more work.
The reason I am suggesting them is it seems the direction the thread was going and would
possibly satisfy the op's needs.
I've designed MTM with the Usher 8945P and 8945A:
http://www.geocities.com/woove99/Spkrbldg/Usher_MTM/Usher_MTM.htm
http://www.geocities.com/woove99/Spkrbldg/8945A_versions.htm
The T/S parameters of the P and A versions are virtually identical. For dual woofers, 1.0 cu ft is a minimum volume for a vented design. Ideally, if you want to have low tuning with a good amount of bass, you'll need 1.5 to 1.7 cu ft.
If you want to use a subwoofer, you can use a .75 to 1.0 cu ft sealed box for a -3 dB point of 71 to 74 Hz with a nice 2nd order rolloff. This will be perfect for use with a subwoofer with 60 to 80 Hz crossover setting on an HT receiver.
If you like warm and tuneful midrange, the Scanspeak paper cone or the Usher carbon/fiber cone may fit your taste better. In fact, these are the lowest distortion 7" drivers you can get currently. If you like to feel a touch of detail in the upper midrange, a bit higher odd order harmonic distortions from metal cone drivers can do a trick for you. I don't like this, but you may like distortions!
The Neo3PDR is the best non-dome tweeter according to Zaph's test. Its distortion profile is excellent. No doubt 2 kHz or even 1.5 kHz LR4 may be possible. But according to its frequency response (see below), 1.7 to 1.8 kHz LR4 should be the lowest possible point for this tweeter.
A low xover point is preferred for an MTM design. The lower, the better. I'd go with the Seas or the Peerless 810921 tweeter (as in my design) if you want an MTM. The Neo3PDR should be an excellent choice for a TMM 2.5 way design.
http://www.geocities.com/woove99/Spkrbldg/Usher_MTM/Usher_MTM.htm
http://www.geocities.com/woove99/Spkrbldg/8945A_versions.htm
The T/S parameters of the P and A versions are virtually identical. For dual woofers, 1.0 cu ft is a minimum volume for a vented design. Ideally, if you want to have low tuning with a good amount of bass, you'll need 1.5 to 1.7 cu ft.
If you want to use a subwoofer, you can use a .75 to 1.0 cu ft sealed box for a -3 dB point of 71 to 74 Hz with a nice 2nd order rolloff. This will be perfect for use with a subwoofer with 60 to 80 Hz crossover setting on an HT receiver.
If you like warm and tuneful midrange, the Scanspeak paper cone or the Usher carbon/fiber cone may fit your taste better. In fact, these are the lowest distortion 7" drivers you can get currently. If you like to feel a touch of detail in the upper midrange, a bit higher odd order harmonic distortions from metal cone drivers can do a trick for you. I don't like this, but you may like distortions!
The Neo3PDR is the best non-dome tweeter according to Zaph's test. Its distortion profile is excellent. No doubt 2 kHz or even 1.5 kHz LR4 may be possible. But according to its frequency response (see below), 1.7 to 1.8 kHz LR4 should be the lowest possible point for this tweeter.
A low xover point is preferred for an MTM design. The lower, the better. I'd go with the Seas or the Peerless 810921 tweeter (as in my design) if you want an MTM. The Neo3PDR should be an excellent choice for a TMM 2.5 way design.
ShinOBIWAN said:
Absolutely, it not a means to avoid the crossover issue.. What I had written:
"..you could skip a lot of the complexity surrounding crossovers by using an active digital crossover (and more amplifiers). (..and of course there are compromises there as well.)"
(-perhaps it was over-broad.
)Jay_WJ said:
Jay_WJ said:
Nice designs!
And likely what Ceibal is looking for.
Also, thank you for the update on the PE cabinets.
Ceibal said:
You don't understand.
Luckily you don't have to really understand, for that you have basic low freq. computer modeling.
Search for the basic version of WinISD and input Zaph's measured values for the Usher Driver under the Database maintenance section. Save it, and then do some modeling with it.
That will give you a starting point for just this limited area of loudspeaker design. Its not super accurate, and it doesn't take into account things like reductions in volume to drivers/bracing/etc., floor bounce, room gain, and baffle step loss and the resulting need for compensation.
Note that I concur with Jay's assessment for the Ushers with 1-1.75 cubic feet per dual driver enclosure. Considering room gain and moderate BSC, I rather liked what I was getting with 1.75 cubic ft. tunned to 28 Hz.
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