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Eminence Alpha 15A (Double Fifteen) playing Reggae
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Young Croc
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Points: 1063 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Gee136 Quote  Post ReplyReply Direct Link To This Post Posted: 20 May 2014 at 11:55am
Originally posted by Elliot Thompson Elliot Thompson wrote:


Sometimes you need to ask yourself if you are achieving the sound you desire or, are you just getting what others feel is the right sound for you based on their concepts.

You really need to know what you want, and having a good understanding of all the TS Parameters will help tremendously. It allows you to pinpoint on areas others overlook or just don’t care about. If the loudspeaker does not offer TS Parameters, you need to measure the loudspeaker. With the amount of software available on the market today, there is no need to speculate which loudspeaker parameter is correct when you are subjected to get the parameters from others.   

You also need to build your own design. Too many people think they are designers and cannot even figure out WinISD, which is the most simplistic loudspeaker simulator on the market

The keyword here is “You.” If you are not willing to make the effort (get your hands dirty) don’t expect anyone else to do it for you.

And of course, the naysayers that get argumentative when you don’t agree with their opinions, which are not based on real world experience, bid them good day and move on.

 

Best Regards,

This has got to be ONE of the most sincere & REAL statement ever written on this board, well done Elliot real Man business Clap 

Respect............. Big smile
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When Goverment ah play, infidels, ginals & masqueraders run away.....
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Points: 217 		Post Options Post Options   Thanks (0) Thanks(0)   Quote crossed Quote  Post ReplyReply Direct Link To This Post Posted: 20 May 2014 at 4:49pm
My interest was piqued, I meant to keep an eye on this thread.  How did the testing turn out?
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I completely forgot about those speakers. Bass is the least of my worries. At the moment, I am researching 192 kHz audio interfaces as that will increase the overall quality of the sound than building another sub cabinet.

Best Regards,
Elliot Thompson
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Originally posted by Elliot Thompson Elliot Thompson wrote:

Originally posted by TMH Music TMH Music wrote:

@Elliot, more details please!!!! What are you driving them with? How big is the cab? What's it tuned to? Just looked at the T/S for Alpha 15a, Qts 1.26?!, BL 7.7???!!!!!!!! VAS 260L!! Is it just me, or does this driver have absolutely no right whatsoever, to sound this good, unless the cab is tuned to a sub-sonic frequency and is 1000 litres+ internal volume? And there was me thinking I knew a bit about speaker design, I'm obviously Manuel (I know nothing!!) .

Going to throw my rule book away now!

Edit for incorrect VAS. Also just crunched the numbers, 12300 litre cabinet, tuned to 12.4Hz!!!
 
Bear in mind, those speakers are in the wrong box (Designed for the RCF L15 P540 not the Eminence Alpha 15A). I believe the amplifier used was the 1986, 4 ru Peavey CS 800 playing the bass or the 1976 version on the left channel. I already took the drivers out of the cabinet and tossed them in back their cardboard boxes. As I mentioned, in another thread, I don’t use high pass filtering, which plays a factor on the sound.
 
Best Regards,
 


Hi Eliiot Just wondering how do you protect the drivers from over excursion at low frequencies without a HPF? 

May have been covered in the other thread but I'm not sure which you mean?
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Originally posted by TmanG TmanG wrote:

Originally posted by Elliot Thompson Elliot Thompson wrote:



Originally posted by TMH Music TMH Music wrote:

@Elliot, more details please!!!! What are
you driving them with? How big is the cab? What's it tuned to? Just looked at
the T/S for Alpha 15a, Qts 1.26?!, BL 7.7???!!!!!!!! VAS 260L!! Is it just me,
or does this driver have absolutely no right whatsoever, to sound this good,
unless the cab is tuned to a sub-sonic frequency and is 1000 litres+ internal
volume? And there was me thinking I knew a bit about speaker design, I'm
obviously Manuel (I know nothing!!) <img src="file:///C:/DOCUME~1/DELLIN~1/LOCALS~1/Temp/msoclip1/02/clip_image001.gif" height="32" width="32" align="middle" />.



Going to throw my rule book away now!



Edit for incorrect VAS. Also just crunched the numbers, 12300 litre cabinet,
tuned to 12.4Hz!!!


 


Bear in mind, those speakers are in the wrong box (Designed
for the RCF L15 P540 not the Eminence Alpha 15A). I believe the amplifier used
was the 1986, 4 ru Peavey CS 800 playing the bass or the 1976 version on the
left channel. I already took the drivers out of the cabinet and tossed them in
back their cardboard boxes. As I mentioned, in another thread, I don’t use high pass filtering,
which plays a factor on the sound.


 


Best Regards,


 







Hi Eliiot Just wondering how do you protect the drivers from over excursion at low frequencies without a HPF? 

May have been covered in the other thread but I'm not sure which you mean?



The impedance of the driver rises within 20 – 25 Hz region in the enclosure. This rise is due to how the driver is reacting in the enclosure. As in the impedance rise, the driver resistance increases. The higher the resistance the less voltage loudspeaker will absorb.   

For example, if an 8 ohm nominal loudspeaker is 35 ohms @ 18 Hz in an enclosure, and, you are feeding the driver an amplifier that offers 89.4 volts (1000 watts) @ 8 ohms, the loudspeaker will not be subjected to 89.4 volts (1000 watts) @ 18 Hz. The voltage will be lower due to the higher resistance. And of course, the lower the volts, the lower the cone movement.   

So under the given scenario, the loudspeaker would absorb around 42 volts @ 18 Hz on a 35 ohm load from an amplifier that delivers 89.4 volts @ 8 ohms.   

Measuring (Not simulating) the impedance curve in the enclosure, will tell you where the true impedance peaks lies.

Best Regards,
Elliot Thompson
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Points: 60 		Post Options Post Options   Thanks (0) Thanks(0)   Quote fourway hornloaded Quote  Post ReplyReply Direct Link To This Post Posted: 25 May 2014 at 11:40pm
The mechanism is real but the explanation is confusing. There is no voltage absorbtion.

If the amplifier puts out 89 Volts, the loudspeaker gets 89 Volts.

Whereas 89 Volts cause 11,1 Amps in an 8 Ohm load, that same voltage causes only 2,5 Amps in a 35 Ohm load. That's how higher in-box impedance at certain frequencies causes less cone movement. In other words, 89 Volts cause 1000 Watts of power in an 8 Ohm resistance, but only 226 Watts in 35 Ohms.

No pun intended, just to make it easier for those trying to grasp the basics.
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Originally posted by fourway hornloaded fourway hornloaded wrote:

The mechanism is real but the explanation is confusing. There is no voltage absorbtion.

If the amplifier puts out 89 Volts, the loudspeaker gets 89 Volts.

Whereas 89 Volts cause 11,1 Amps in an 8 Ohm load, that same voltage causes only 2,5 Amps in a 35 Ohm load. That's how higher in-box impedance at certain frequencies causes less cone movement. In other words, 89 Volts cause 1000 Watts of power in an 8 Ohm resistance, but only 226 Watts in 35 Ohms.

No pun intended, just to make it easier for those trying to grasp the basics.


Sorry that is not correct.

I am talking about impedance versus frequency of a loudspeaker. If someone looks at an impedance versus frequency chart of a loudspeaker, it will not show you the amount of amperage consumed by the loudspeaker at particular wattage. What it will show you is the frequency bandwidth, the impedance load at the given frequencies and, at times the phase.

By you adding amperage in the equation, it creates confusion for the amperage drawn from the A.C. Receptacle will vary pending on what part of the world you live in.

Power Consumption

1000 watts on a 120-volt line source: 8.333 amperes
1000 watts on a 240-volt line source: 4.166 amperes
1000 watts on a 230-volt line source: 4.347 amperes
1000 watts on a 200-volt line source: 5.0 amperes
1000 watts on a 110-volt line source: 9.090amperes
1000 watts on a 100-volt line source: 10.0 amperes
1000 watts on a 220-volt line source: 4.545 amperes

This is precisely the reason I did not add amperage in my explanation.

Best Regards,






Edited by Elliot Thompson - 26 May 2014 at 3:37am
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Points: 270 		Post Options Post Options   Thanks (0) Thanks(0)   Quote TmanG Quote  Post ReplyReply Direct Link To This Post Posted: 28 May 2014 at 11:22pm
Originally posted by Elliot Thompson Elliot Thompson wrote:


Originally posted by TmanG TmanG wrote:

Originally posted by Elliot Thompson Elliot Thompson wrote:



Bear in mind, those speakers are in the wrong box (Designed
for the RCF L15 P540 not the Eminence Alpha 15A). I believe the amplifier used
was the 1986, 4 ru Peavey CS 800 playing the bass or the 1976 version on the
left channel. I already took the drivers out of the cabinet and tossed them in
back their cardboard boxes. As I mentioned, in another thread, I don’t use high pass filtering,
which plays a factor on the sound.


Best Regards,



Hi Eliiot Just wondering how do you protect the drivers from over excursion at low frequencies without a HPF? 

May have been covered in the other thread but I'm not sure which you mean?



The impedance of the driver rises within 20 – 25 Hz region in the enclosure. This rise is due to how the driver is reacting in the enclosure. As in the impedance rise, the driver resistance increases. The higher the resistance the less voltage loudspeaker will absorb.   

For example, if an 8 ohm nominal loudspeaker is 35 ohms @ 18 Hz in an enclosure, and, you are feeding the driver an amplifier that offers 89.4 volts (1000 watts) @ 8 ohms, the loudspeaker will not be subjected to 89.4 volts (1000 watts) @ 18 Hz. The voltage will be lower due to the higher resistance. And of course, the lower the volts, the lower the cone movement.   

So under the given scenario, the loudspeaker would absorb around 42 volts @ 18 Hz on a 35 ohm load from an amplifier that delivers 89.4 volts @ 8 ohms.   

Measuring (Not simulating) the impedance curve in the enclosure, will tell you where the true impedance peaks lies.

Best Regards,

That makes perfect sense to me Elliot thank you for the response.

Does the impedance of a bass enclosure not fall back down to normal levels around 10hz? 

Would in this instance given a strong enough signal in this region, either through subsonic feedback or the music itself, cause concern about over-excursion? Is it the case that electronic processing units rarely let any signal at that frequency pass though at significant level or some other reason that you feel comfortable running your system with no hpf?

Just curious is all as I've always operated under the adage that operating an enclosure with no hpf is risky
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Originally posted by TmanG TmanG wrote:

Originally posted by Elliot Thompson Elliot Thompson wrote:


Originally posted by TmanG TmanG wrote:

Originally posted by Elliot Thompson Elliot Thompson wrote:



Bear in mind, those speakers are in the wrong box (Designed
for the RCF L15 P540 not the Eminence Alpha 15A). I believe the amplifier used
was the 1986, 4 ru Peavey CS 800 playing the bass or the 1976 version on the
left channel. I already took the drivers out of the cabinet and tossed them in
back their cardboard boxes. As I mentioned, in another thread, I don’t use high pass filtering,
which plays a factor on the sound.


Best Regards,



Hi Eliiot Just wondering how do you protect the drivers from over excursion at low frequencies without a HPF? 

May have been covered in the other thread but I'm not sure which you mean?



The impedance of the driver rises within 20 – 25 Hz region in the enclosure. This rise is due to how the driver is reacting in the enclosure. As in the impedance rise, the driver resistance increases. The higher the resistance the less voltage loudspeaker will absorb.   

For example, if an 8 ohm nominal loudspeaker is 35 ohms @ 18 Hz in an enclosure, and, you are feeding the driver an amplifier that offers 89.4 volts (1000 watts) @ 8 ohms, the loudspeaker will not be subjected to 89.4 volts (1000 watts) @ 18 Hz. The voltage will be lower due to the higher resistance. And of course, the lower the volts, the lower the cone movement.   

So under the given scenario, the loudspeaker would absorb around 42 volts @ 18 Hz on a 35 ohm load from an amplifier that delivers 89.4 volts @ 8 ohms.   

Measuring (Not simulating) the impedance curve in the enclosure, will tell you where the true impedance peaks lies.

Best Regards,


That makes perfect sense to me Elliot thank you for the response.

Does the impedance of a bass enclosure not fall back down to normal levels around 10hz? 

Would in this instance given a strong enough signal in this region, either through subsonic feedback or the music itself, cause concern about over-excursion? Is it the case that electronic processing units rarely let any signal at that frequency pass though at significant level or some other reason that you feel comfortable running your system with no hpf?

Just curious is all as I've always operated under the adage that operating an enclosure with no hpf is risky



If you mean normal as nominal load of two 8-ohm drivers wired parallel to equal 4 ohms nominal, no. The impedance is higher than 4 ohms nominal at 10 Hertz if we are using the Eminence Alpha 15A woofers in the reflex box played in the videos as a means of reference. Of course, results will vary pending on how the driver(s) are reacting in the enclosure of the design in question.

One must also consider the dB ratio comparing 10 Hz to 20 Hz. Almost always there is a significant reduction starting from 20 Hz to 10 Hz from the source (musical content). I might add most audio processors internal HPF starts to activate below 20 Hz and may be around – 1.5 dB to -3 dB @ 10 Hz pending on the audio device in question.   

Measuring every piece of equipment used in the audio chain will show what is the weakest link starting from the source (musical content) to loudspeaker (woofer).



Best Regards,

Edited by Elliot Thompson - 29 May 2014 at 4:39am
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Points: 2435 		Post Options Post Options   Thanks (0) Thanks(0)   Quote app Quote  Post ReplyReply Direct Link To This Post Posted: 12 November 2014 at 10:38am
This is an interesting topic!

ET have you already started planning the box for these?
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Id like to see what the simulation for this would look like.Just to learn a trick or twoSmile
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How should the impedance/x-max/transfer function magnitude (?) ratio be read?

 What I mean is if the impedance is low at lets say 35hz and hi at 65hz and the speaker is given x amount of watts would that cause the frequency range of the speaker to even. Althou it may seem in the transfer function magnitude line that theres not much happening at 35 hz.

How should the x-max be in relation to impedance?

How do you tune your box so that you can play it without using a highpass filter?

edit. b&c sub 18 with 4 different drivers all given their max rms signal. What does the impedance curve tell me? Which one of the lines is the "best"?
 








Edited by app - 12 November 2014 at 2:11pm
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