New single BR |
Post Reply | Page <1 23456 7> |
Author | |
snowflake
Old Croc Joined: 29 December 2004 Location: Bristol Status: Offline Points: 3118 |
Post Options
Thanks(0)
|
if you want highest power per volume then look at B6 alignment
|
|
Crashpc
Registered User Joined: 26 February 2008 Location: Czech Republic Status: Offline Points: 463 |
Post Options
Thanks(0)
|
Of course, I meant highest power density with some fixed requirements like frequency range, or total output in some way. If there were no boundaries, most power would be achieved very different way. Two 18IPALs would definitely outdo one 21DS115 in the same box volume for SPLmax, no doubt. |
|
Nikon and Canon people should not be married to each other. Why did you let this happen?
|
|
MarjanM
Old Croc Joined: 10 February 2005 Location: Macedonia Status: Offline Points: 7810 |
Post Options
Thanks(0)
|
I have done tons of actual box/driver measurements to confirm that the sims are not entirely wrong.
They are more right then wrong. At the time when we tested different high power 18 inch drivers for our reflex products this was confirmed by measurements too. So we didnt go with the high BL driver at the end. They do have more excursion, but when they are less sensitive, you need to apply more power to get them moving and compensate what lower BL drivers can do without the need of so massive excursion. If your goal is more infra, then subwoofer, go with high BL. If you need to have more general purpose subs cpable of covering wide type of music material, then go with the lower BL drivers.
|
|
Marjan Milosevic
MM-Acoustics www.mm-acoustics.com https://www.facebook.com/pages/MM-Acoustics/608901282527713 |
|
Crashpc
Registered User Joined: 26 February 2008 Location: Czech Republic Status: Offline Points: 463 |
Post Options
Thanks(1)
|
I would mostly agree. For sake of getting to the point, I will skip these agreed parts. Here is the core of the issue I see:
That piece of text is not right. One needs to apply more VOLTAGE to the high BL speaker, to even get to the same power. High BL driver fed with the same voltage will get less power. If you fed the high BL driver more voltage to feed equal power compared to the low BL driver, then it would be fair power comparison. It is not in sims and it is not with same approach/signal on particular amplifier in real life too. Voltage does not equal power, and that´s why the speaker output assesment is very flawed. We would continue to discuss how hard is to feed the speaker, how hard is to find the suitable amp, and I would agree. Yet it is different topic. Again. All else being equal, at no point speaker with more Newton force per Watt will create less displacement volume by its excursion, or exhibit less sound pressure. It is not possible to break basic physics with simulation with unequal circumstances for compared speakers. There are caveats and exceptions to this, of course, but as nobody even touched these, I will ignore these for the moment. Edited by Crashpc - 27 March 2019 at 6:27pm |
|
Nikon and Canon people should not be married to each other. Why did you let this happen?
|
|
MarjanM
Old Croc Joined: 10 February 2005 Location: Macedonia Status: Offline Points: 7810 |
Post Options
Thanks(0)
|
Voltage equals power when you connect a speaker. Right? So why is my part wrong?
If a given 8ohm driver does 95db with 2.83V applied, and the other makes 96db with same 2.83V applied, how do you compensate the 1db difference if you dont apply 30% more power? (higher voltage if we want to be pedantic) |
|
Marjan Milosevic
MM-Acoustics www.mm-acoustics.com https://www.facebook.com/pages/MM-Acoustics/608901282527713 |
|
Crashpc
Registered User Joined: 26 February 2008 Location: Czech Republic Status: Offline Points: 463 |
Post Options
Thanks(0)
|
No, voltage is not necessarily equal power. Power *can equal Voltage times current. For current to flow, we need a conductor - speaker coil, or rather the whole speaker. Nominal impedance rating will not cut it. Different 8Ohm speakers have different resistance and impedance too. That will cause different amount of current to flow to the speaker at the particular voltage, and it will result in different amount of power applied. The difference can be very significant. This difference correlates with speaker Bl to a point. All else being equal, higher Bl driver will have higher impedance, less current draw, so less power will be applied to it, so it will appear less sensitive. Those speakers rather don´t have 8Ohm across their frequency range. In extremes to show at least something, High Bl 8Ohm driver can have impedance peak of about 100-200Ohm. If you apply 2,83V to it, only 0,04W of power (P=U*I, I=U/R) will be applied. Not 1Watt. At 0,04W for 95db, the speaker is very efficient then... This peak happens to weaker drivers too. The point is, the peak is always lower, and it is more in phase. That means two things. One thing is that more power will flow for the same voltage, and that the apparent power = real power = all burnt as heat. Hope it helped a little bit. The knowledge of this is no win though. It comes with all kinds of obstacles and trouble to make use of speaker with such excotic and strong motor. You still have your important point right. If one has an amplifier, and needs better speaker, higher Bl speaker might not be a good way, unless he is willing to change more expensive things in his setup for this advantage to take any effect. It seems that to fully utilize such driver, one needs amp marked as "4000W" (if not more) for each driver (even though the power will not need to be that high in real), and rather D-Class with Switched mode power supply amplifier, because even before counting for the nominal amplifier efficiency, one will burn 50% of the energy as a heat on the amplifier side on conventional AB/Toroidal supply amplifier. Due to the phase shifts, and difference between real power and apparent power. Edited by Crashpc - 27 March 2019 at 9:10pm |
|
Nikon and Canon people should not be married to each other. Why did you let this happen?
|
|
smitske96
Young Croc Joined: 16 February 2016 Location: The Netherlands Status: Offline Points: 1085 |
Post Options
Thanks(0)
|
At the moment it's the itech 8000, still one one the bigger amps available.
After that you have powersoft k20, X8 , pkn xe10000 and I will not mention the H8 Other update from my side of the project: I can get a really good deal on 4 pro grade grills, and suitable for a 18" BR box (still a bit smal, but I'll make it work).
|
|
Crashpc
Registered User Joined: 26 February 2008 Location: Czech Republic Status: Offline Points: 463 |
Post Options
Thanks(0)
|
These are nice amps, and if speaker impedance is matched to the amplifier capabilities right, you are safe. What applies for 21DS115 still applies for 18"s too.... Get most refined drivers with best excursion capabilities, low Qes and high Bl. You will enjoy even more power density, as for example with B&C, same motor and coil structure is applied on more speaker sizes. Same motor, with just smaller speaker cone. Same analogy with V8 in a Minicooper. 😀 = Mordor, murder, terror....
Edited by Crashpc - 27 March 2019 at 9:32pm |
|
Nikon and Canon people should not be married to each other. Why did you let this happen?
|
|
Crashpc
Registered User Joined: 26 February 2008 Location: Czech Republic Status: Offline Points: 463 |
Post Options
Thanks(0)
|
MarjanM: Here is example between 18SW100 and
21DS115 in 180l box with bassreflex port tuned at 35HZ. I haven´t seen simulator software capable of showing all in
one graph, so I will pick WinISD and I will pick discrete frequency to compare
and see. We feed both speakers exactly one watt of real power at 80Hz(
real power = power burnt as heat, that´s what we should count when we are after
speaker output and performance and loading capabilities). How do we do that? We set Power P at 1Watt. P = U*I*cos(θ). We do not
know current “I” in the advance, we count it from the equation I = U/Z. We put
that in our first equation. P = U*(U/Z)*cos(θ). We want to
feed one watt of power. Therefore P = 1W, therefore: 1 = U*(U/Z)*cos(θ). We know Z
and Cos(θ) from the simulation. It is shown in the “Impedance” and “Impedance
phase” graphs. At 80Hz, Z
is 14,54 for 21DS115 and 11,98 Ohms for 18SW100. Cosinus(θ) is function of
phase angle. 64° and 54,55° means cos(θ) for these speakers is 0,438 and 0,58 respectively. So, for two
speakers 1 =
U*(U/14,54)*0,438 for 21DS115 and 1 =
U*(U/11,98)*0,58 for 18SW115. For 1Watt
of power, the voltage needed to go into the each speaker is: 5,77V for 21DS115
at 80Hz. 4,55V for
18SW100 at 80Hz. Now let´s
look at graphs with this value set (21DS115 is green). Don´t forget to look
only at 80Hz, because in different frequency points, the situation is
different. At some
frequencies, 21DS115 would not run away or win, in some frequencies it runs
further: Interesting
thing is, what Winisd thinks is the power in watts, down in the window. It says
3,9W for 18SW100, while it says 6,5W for 21DS115…. That is not the power going to the speaker… Taking more cone displacement capabilities of 21DS115 and larger coil into account, it should outperform 18SW100 by about 3dB at SPLmax I would guess. //I see different outcome between my first and second try. First time I didn´t put that much effort into describing general thing and counting with tiny fractions. There is still room for mistakes, things take time, which I don´t have in the required amount... Edited by Crashpc - 28 March 2019 at 5:42pm |
|
Nikon and Canon people should not be married to each other. Why did you let this happen?
|
|
MarjanM
Old Croc Joined: 10 February 2005 Location: Macedonia Status: Offline Points: 7810 |
Post Options
Thanks(0)
|
Why are you calculating at 80hz. The problem is at 55-60hz, not 80 hz. At 80 hz you will probably lowpass and be at -3 db or so against the average sensitivity.
Edited by MarjanM - 28 March 2019 at 6:45pm |
|
Marjan Milosevic
MM-Acoustics www.mm-acoustics.com https://www.facebook.com/pages/MM-Acoustics/608901282527713 |
|
Crashpc
Registered User Joined: 26 February 2008 Location: Czech Republic Status: Offline Points: 463 |
Post Options
Thanks(0)
|
It´s just one randomly picked point. In my last table, it is visible that even at 60Hz, 21DS115 still has 2,25db advantage over 18SW100, both at 1W. While 21DS115 having larger coil, it is expectable there will be 3db maxSPL difference. The last graph was created the same way as 80Hz calculation, I just put each calculation at "respective 10Hz mark" in the graph to see the whole picture across frequency range. I cut my subs at 95Hz for PA.
Edited by Crashpc - 28 March 2019 at 8:58pm |
|
Nikon and Canon people should not be married to each other. Why did you let this happen?
|
|
MarjanM
Old Croc Joined: 10 February 2005 Location: Macedonia Status: Offline Points: 7810 |
Post Options
Thanks(0)
|
This is all good, but my comment was high bl vs not so high bl drivers. Not 21 vs 18. That one is very obvious.
Try that same math and compare 18SD115 and 18TLW3000. And take 55 or 60hz or whichever frequency it the point of the dip at the 18sd115. Or 18sd115 vs 18sw100. It would be interesting to see that comparison.
|
|
Marjan Milosevic
MM-Acoustics www.mm-acoustics.com https://www.facebook.com/pages/MM-Acoustics/608901282527713 |
|
Post Reply | Page <1 23456 7> |
Tweet |
Forum Jump | Forum Permissions You cannot post new topics in this forum You cannot reply to topics in this forum You cannot delete your posts in this forum You cannot edit your posts in this forum You cannot create polls in this forum You cannot vote in polls in this forum |