Hi there. I'm new to the forum, and new to building speakers, but I'm about to have a crack at making my first pair!
I'm planning to make a pair of little full-range sealed cabinet speakers for mono and limited band width mixing, similar to an Aurotone style speaker.
I have purchased a Monitor Audio MR Centre speaker like this -Monitor Audio MR Centre Speaker to use the two drivers from. The Monitor audio is also a sealed cabinet, presumably optimised for mid band frequencies, so I thought these drivers might be an okay starting point for what I want.
As a starting point for my single driver mix cubes, am I right in thinking that I can half the volume of the two driver of the MA centre speaker?
By doing this I've used; Qtc = Qts * (Vas / Vc + 1)1/2 and figured that the Monitor Audio has a Qtc of 0.6075. (Qts 0.812, Vas 6.1846, Vc 3.133L)
My limited research seems to be suggesting that a Qtc of 0.707 is optimal, so I've tried this same formula with a variety of similar volumes (slightly high and lower etc) and discovered that a Vc of 2.55, would give me a value Qtc of 0.707. This is where everything is starting to go wrong though.
Whenever I try to use other online calculators to work out the optimum volume, assuming a Qtc of 0.707, they say it is not possible, the Qtc has to be higher than the Qts. The reality is I have no idea what any of this means in the real world, and I don't understand how I can run one formula one way and get the right value, then a different formula which says something completely different.
The online tools all seem to be including the Fs value, which the [Qtc = Qts * (Vas / Vc + 1)1/2] formula does not. If I try and get a test Qtc value of say 8.13 (slightly higher than the Qts), using the online tools it seems to suggest I need a volume of 71,000L. That's a little big for my desktop!
So where am I going wrong?
I'm planning to make a pair of little full-range sealed cabinet speakers for mono and limited band width mixing, similar to an Aurotone style speaker.
I have purchased a Monitor Audio MR Centre speaker like this -Monitor Audio MR Centre Speaker to use the two drivers from. The Monitor audio is also a sealed cabinet, presumably optimised for mid band frequencies, so I thought these drivers might be an okay starting point for what I want.
As a starting point for my single driver mix cubes, am I right in thinking that I can half the volume of the two driver of the MA centre speaker?
By doing this I've used; Qtc = Qts * (Vas / Vc + 1)1/2 and figured that the Monitor Audio has a Qtc of 0.6075. (Qts 0.812, Vas 6.1846, Vc 3.133L)
My limited research seems to be suggesting that a Qtc of 0.707 is optimal, so I've tried this same formula with a variety of similar volumes (slightly high and lower etc) and discovered that a Vc of 2.55, would give me a value Qtc of 0.707. This is where everything is starting to go wrong though.
Whenever I try to use other online calculators to work out the optimum volume, assuming a Qtc of 0.707, they say it is not possible, the Qtc has to be higher than the Qts. The reality is I have no idea what any of this means in the real world, and I don't understand how I can run one formula one way and get the right value, then a different formula which says something completely different.
The online tools all seem to be including the Fs value, which the [Qtc = Qts * (Vas / Vc + 1)1/2] formula does not. If I try and get a test Qtc value of say 8.13 (slightly higher than the Qts), using the online tools it seems to suggest I need a volume of 71,000L. That's a little big for my desktop!
So where am I going wrong?
Yes, half the volume of the box you ar epillaging is a good starting point. Volume of a sealed box is quite tolerant, A Q between 0.5 and 1.0 can be found useful. ).707 is mac flat amplitude. Internal damping (required) can act to increase the apparent volume by up to about 20%.
dave
dave
Thanks for the quick reply Dave, any idea why I can get a Qtc value of 0.707 with a volume of 2.55L, with one calculation, but then with the Fs and Speaker dia values are included everything goes wrong?
I haven’t paid attention to the math for decades, i just use what is spit out by my modelling software.
dave
dave
May I suggest the Dayton PA130-8 for this project? It’s high sensitivity, takes power well, sounds great, and is inexpensive. It’s 5in size similar to Auratone paper cone. I could be wrong about the size but the Avantone box looks like it’s about 6-7L and PA130-8 in 0.25cu ft (7L) vented will tune to 80Hz or sealed down to 160Hz.
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Thanks for the reply, I've already got hold of the drivers. I'm hoping they are suitable. And I'm after a sealed enclosure rather than Vented. Maybe the Dayton for another project! 😉
Substituting Qts, Vas and Vc (Vb) in the formula Qtc = Qts * (Vas / Vb + 1)^1/2, makes Qtc=1.4, not Qtc=0.6075.
Midbass in the MR Centre IS NOT a fullrange driver!
You MUST use a genuine fullrange speaker. A bad one, to be similar to the Avantone MixCube or Auratone 5c.
Yes, you will get Qtc=1.4 with one midbass (see my previous post).
It means it is not possible. The online calculators are right, you can not obtain Qtc lower than Qts.
Again, the on line calculators are right.
Check out this very useful thread:
Auratone DIY
I have built a pair with the Maplin drivers, which are apparently no longer available. The thread has some good explanations of what makes a good clone.
Best,
/G
Auratone DIY
I have built a pair with the Maplin drivers, which are apparently no longer available. The thread has some good explanations of what makes a good clone.
Best,
/G
Thanks. I've read that thread a few times already!! And others....so much to learn, and so many mistakes to make.
It's a shame about the missing Maplin driver Dave suggests. I was initially going to use a Visaton FR12 8ohm as an alternative instead, as recommended in the thread at some point, but then I wondered if I could spend a little more money and get a slightly better performing driver. I think getting this Monitor Audio donor speaker was my first mistake.
Essentially, I like the concept of a full range driver, in a very small sealed box.
So I've just been looking at the Dayton PA130-8 suggested in this thread, but also RS100-8 4" which is a little more money, but gets mixed reviews.
The RS100-8 is a fine sounding and well built cast frame driver. It’s 3.5in though and a totally different class as far as SPL and max punch that can be delivered vs the PA130-8 which is a 5in pro audio driver. The PA130-8 doesn’t reach as high or is as smooth but it’s main range of mids ia quite usable and sounds very good.
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