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Multi-Way Conventional loudspeakers with crossovers

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Old 20th September 2018, 08:39 AM   #31
phase_accurate is offline phase_accurate
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When the Faital 12RS550 was introduced last year they mentioned that it was intended for HiFi and studio monitoring purposes. It has one of the lowest EBPs of the Faital range and could be used for a smalll coffin as well.
But there are two things that I don't like about it: It doesn't have a shorting ring and its dustcap looks even larger then the one on the Beyma 12lx60v2 despite the smaller voice-coil.

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Old 20th September 2018, 09:05 AM   #32
burgunder is online now burgunder  Denmark
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A little inspiration.

Fusion
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Old 20th September 2018, 10:27 AM   #33
KaffiMann is online now KaffiMann  Norway
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I do not mind the 12LX60v2 at all, but people, please do not look at qts and vas alone, fs does play an important role in all of this, and ofcourse two drivers with qts 0,34 will have very different vas if one has fs 35hz and the other 50hz. Please do not forget to take all the parameters into account.
Another thing is sensitivity, as far as I can tell, sensitivity is voted the most important aspect here.
And 2/pi - halfspace figures should be fine, there's a snowballs chance in hell you can realisticly get 92dbw at 40hz/60liters in fullspace, just forget it.
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Old 20th September 2018, 11:39 AM   #34
Paul Vancluysen is offline Paul Vancluysen  Belgium
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Quote:
Originally Posted by KaffiMann View Post
I do not mind the 12LX60v2 at all, but people, please do not look at qts and vas alone, fs does play an important role in all of this, and ofcourse two drivers with qts 0,34 will have very different vas if one has fs 35hz and the other 50hz. Please do not forget to take all the parameters into account.
Another thing is sensitivity, as far as I can tell, sensitivity is voted the most important aspect here.
And 2/pi - halfspace figures should be fine, there's a snowballs chance in hell you can realisticly get 92dbw at 40hz/60liters in fullspace, just forget it.
Of course fs has to be in a certain range. But with the F3, cabinet volume and sensitivity requirements, fs has to be automatically in the good range, being 40 - 50 Hz.

Indeed we have to forget the 92dB + requirement in full space, 88 to 90 dB full space seems te be more realistic for this cabinet volume.

W.r.t. to the source resistance of the basreflex system, what will be the preferred choice for the X-over coils? Air coils, ferrite coils, zero ohm coils,... I think it is important to take already an estimation for Rdc of the coils in the basreflex system design for the driver choice. In case of air coils, I had the idea to take already 0.5 Ohm for it.

And what about the Zout of tube amplifiers? It has even more influence on the system response. If the speaker has to be tube amplifier compliant we have to take into account also the amplifier Zout.

I think it will be difficult to design a flat bass SPL for both solid state and tube amplifier. Maybe we have to accept some SPL tilt for the tube amplifier? Or make two X-over versions ??...

What are the ideas about these issues?
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Old 20th September 2018, 11:52 AM   #35
KaffiMann is online now KaffiMann  Norway
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Well, looking at the wind direction here for a bit, people tend to suggest more expensive drivers, if each driver costs 150$ each, you have 450$ cost of drivers, which leaves 50$ to spend on xo parts.

I am trying to look at cost a bit more, so maybe the average cost on my shortlist can be 120$...? so 360$ total (hopefully) for drivers, leaving 140$ for more quality xo components and maybe neutrik connectors?

A good xo costs money.
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Old 20th September 2018, 12:27 PM   #36
KaffiMann is online now KaffiMann  Norway
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Sorry about the bump, was just outside the scope of editing.

Edit:
And my personal opinion is that we should maybe optimize filters for ACA just to have a sort of reference point. Go for one filter design, the less complicated the better. Remember: "Less is more" and also KISS (Keep It Simple Stupid!) :-)
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Old 20th September 2018, 02:26 PM   #37
mbrennwa is online now mbrennwa  Switzerland
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Originally Posted by burgunder View Post
A little inspiration.

Fusion
Troels Fusion pops up here all the time. It's a great speaker, and it looks very pretty (at least to my). However, it does not fulfill the "amp friendly" criteria as described in the first post (efficiency, impedance rating).

Quote:
Originally Posted by KaffiMann View Post
And 2/pi - halfspace figures should be fine, there's a snowballs chance in hell you can realisticly get 92dbw at 40hz/60liters in fullspace, just forget it.
I see your point, but I don't agree to give it up so early. I remember I got 92 dB/2.83V/1m into full space when I tried modelling a Supravox 215 GMF in a bass reflex. I'll have to check again, but I believe the box volume was 80 L or so. But yes, 92 dB into free space from a small box is a challenge.

Quote:
Originally Posted by Paul Vancluysen View Post
Of course fs has to be in a certain range. But with the F3, cabinet volume and sensitivity requirements, fs has to be automatically in the good range, being 40 - 50 Hz.

Indeed we have to forget the 92dB + requirement in full space, 88 to 90 dB full space seems te be more realistic for this cabinet volume.
Remember that efficiency is proportional to 1/fs^3. The higher fs, the louder it goes. That's why the right compromise regarding fs (and hence bass extension) DOES allow high efficiency.

Quote:
Originally Posted by Paul Vancluysen View Post
W.r.t. to the source resistance of the basreflex system, what will be the preferred choice for the X-over coils? Air coils, ferrite coils, zero ohm coils,... I think it is important to take already an estimation for Rdc of the coils in the basreflex system design for the driver choice. In case of air coils, I had the idea to take already 0.5 Ohm for it.

And what about the Zout of tube amplifiers? It has even more influence on the system response. If the speaker has to be tube amplifier compliant we have to take into account also the amplifier Zout.

I think it will be difficult to design a flat bass SPL for both solid state and tube amplifier. Maybe we have to accept some SPL tilt for the tube amplifier? Or make two X-over versions ??...

What are the ideas about these issues?
That's good point given our requirement for "weak-amp compatibility". With an 8 Ohm rating of the speaker, the impedance seen by the amp will always be about 6 Ohm or higher. An amplifier with 0.2 Ohm output impedance (not great) will result in a damping factor of 30 or higher. I'd say that's pretty good.

For bass filter coils, I'd suggest avoiding air cores to keep their DC resistance low. There are a number of different core types, and some will provide quite some headroom before saturating. A 0.5 Ohm DC resistance is too much in my view.

Quote:
Originally Posted by KaffiMann View Post
Well, looking at the wind direction here for a bit, people tend to suggest more expensive drivers, if each driver costs 150$ each, you have 450$ cost of drivers, which leaves 50$ to spend on xo parts.

I am trying to look at cost a bit more, so maybe the average cost on my shortlist can be 120$...? so 360$ total (hopefully) for drivers, leaving 140$ for more quality xo components and maybe neutrik connectors?

A good xo costs money.
Good parts do cost money. And I prefer spending money than buying the "wrong" parts. As I wrote in my first post, I'd like to keep costs second priority after quality of the design and parts. Also, the parts costs mentioned earlier (in the polls) was for drivers only.

Quote:
Originally Posted by KaffiMann View Post
my personal opinion is that we should maybe optimize filters for ACA just to have a sort of reference point. Go for one filter design, the less complicated the better. Remember: "Less is more" and also KISS (Keep It Simple Stupid!) :-)
I'd hate to design for a specific amplifier. But since the ACA is a very popular design that comes up as a "typical weak amp" all the time in the Open Source Speaker discussion, I'd agree to keep the ACA in mind as a reference/prototye for the "typical weak amp" that we're trying to accomodate with our design.

Thinking about amplifier output impedance again, I have to say that I have absolutely not idea what the ACA output impedance is. Just in case someone comes along and tells me that that ACA (or some other "prototype weak amp") has a really high output impedance, my answer would be that we need a careful impedance compensation for the whole speaker, giving essentially flat impedance throughout most of the range. All it takes is a few more L, C, and R parts. These compensation parts are only necessary for amps with very high output impedance and can simply be left out with more typical amps.


Soooo, are there any other suggestions for suitable bass drivers? So far we have a few 12" Beymas and a few 10" suggestions. I am sure there's more! Bring it on!
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Old 20th September 2018, 02:58 PM   #38
phase_accurate is offline phase_accurate
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There are some Eighteensound drivers that have been used for HiFi as well. Like the 12nlw9300 for instance. But this one might sound a little bass light due to its low Qes. But the fs of 10 Hz is nice.

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Charles
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Old 20th September 2018, 03:10 PM   #39
KaffiMann is online now KaffiMann  Norway
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Quote:
Originally Posted by mbrennwa View Post
...
Soooo, are there any other suggestions for suitable bass drivers? So far we have a few 12" Beymas and a few 10" suggestions. I am sure there's more! Bring it on!
I'd like to put the Fane Sovereign Pro 12-300 on the short list, it's a "better" version with cast frame etc. compared to the regular Sovereign 12-300. And it's reasonably priced!
Availability might be a problem however, so in it's place (pending on the webshop you decide to order from), I suggest the Fane Sovereign Pro 12-500.
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Old 20th September 2018, 03:55 PM   #40
mbrennwa is online now mbrennwa  Switzerland
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Originally Posted by KaffiMann View Post
I'd like to put the Fane Sovereign Pro 12-300 on the short list, it's a "better" version with cast frame etc. compared to the regular Sovereign 12-300. And it's reasonably priced!
Availability might be a problem however, so in it's place (pending on the webshop you decide to order from), I suggest the Fane Sovereign Pro 12-500.
Qms = 3.04 indicates rather high mechanical losses. Not so great.

What about Eminence DELTA PRO 12-450A and its siblings?
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