A Question on Speaker Driver Efficiency

Thanks to all for all the input - Once again Agon members have proven to be very insightful.

@erik_squies

- I double checked the sensitivity numbers and 4, 8, and 16 ohm speakers have identical sensitivity - 95db, but it's definitely something to verify going forward - different brands may vary

The XSim Crossover Simulator  seems to be for audio crossovers
- In guitar amps/Speaker cabinets for the majority of cases there is no crossover, so I'm wondering if it would be of any use?

FYI, since I know a few of you play instruments - I have now tried a Celestian 8" mid freq driver and an Eminence Legend 10": bass driver.. Both of these are excellent and significantly better than the original drivers in the areas of  sensitivity, dynamics and clarity.

One last question for everyone...
- In parallel - each driver would move at EXACTLY the same time (pretty much)
- in series - would the second speaker in the "chain" be moving slightly behind the first speaker due to lag time through the voicecoil of the first speaker ?
- also, would one speaker be affected by the other?
- Would the human ear be able to discern this?

Thanks again for all the feedback - it's very useful

Cheers - Steve :-)

@williewonka

Excellent questions

1)  yes (in phase)
2) yes but it should be virtually undetectable
3)  In series, there will be increased inductance which will roll off high frequencies (yes). In parallel, inductance seen by the amp is cut in half just like the resistance is. Also, increased current draw from the amp almost always affects linearity (increased distortion). Whether or not this is noticeable depends on the amp and how hard you drive it.
4) the human ear should be able to discern the increased sensitivity of the parallel arrangement without any problem. All the other aspects - highly debatable and largely dependent on the person.

All of the above - my opinion based on experience - certainly not the end all be all as I'm sure others might have different experiences.

"Speaker sensitivity is measured in decibels per 1 watt per 1 meter, but is usually referred to as just decibels [source: JBL]."

For an 8 ohm load, this equates to 2.83 volts. But for a 4 ohm load it’s 2.00 volts and for a 16 ohm load its 4.00 volts. Because the OP said the speakers have the same "sensitivity," this has been accounted for.

And yes, JBL does put more wire and turns in the gap for their higher impedience speakers leading to a high Bl.

In fact, there are cases where the higher impedience model looses travel (Xmax) because of this difference.

And seeing as how JBLs are the only make of speaker that matter in my household, I stand behind the logic that a higher impedience typically leads to a higher Bl.

As to the effects of inductance, I did note that there is interaction between the two speakers in a series set-up (goes beyond inductance) that does not exist in the parallel set-up, and for these reasons I would choose a parallel set-up.  

@ toddalin

The industry standard for as long as I can remember relies on a fixed voltage to assess a loudspeaker's sensitivity - not power input. In this way, it doesn't matter what the loudspeaker's impedance is. All are judged on the same level playing field. No one has to adjust drive level to compensate for a "nominal" impedance rating. All drivers under test get the same voltage applied and no concern is paid to the current drawn - simply the acoustic output that is generated. If the driver or loudspeaker under test's efficiency is sought, then the unit of power  (watt) is a concern - not the unit of force applied (volt). If you had any electrical engineering experience, you'd know this and would stop quoting a JBL cut sheet as "your Bible".

As to the 16 ohm bit, I give up. I did my best to explain it to you and have obviously failed. Know one thing though. You aren't the only knowledgeable JBL "fanboy". I happen to be listening to a pair of 250ti Limiteds that I've had since new (1992). My first pair of speakers was the L19s I bought - probably before you were born...ugh....that hurts to say.... In any case, please take some heartfelt advice that is not meant to demean you or put you down - there is alot more to learn about electrical, acoustical, and mechanical engineering than what you will find in a JBL cut sheet. I know. Before engineering school, I studied the very same cut sheets you clearly obsess over.

The L19 made it’s debut in the 1979 catalog. Seeing as how I’ve been into JBLs since the 60’s, it sounds like you are the newcomer.

I've even developed and make products for use with classic JBLs.

https://youtu.be/pbbS0QYK2_o

http://www.audioheritage.org/photopost/data//500/medium/Resized1.jpg

http://www.audioheritage.org/photopost/data//500/medium/Tweeters1.jpg

I never said that the higher impedience meant that the speaker would have a higher Bl, but allowed for it, and showed several examples to that effect.

You’ve not shown one model that demonstrates otherwise.

As for sensitivity, you are using your definition,. and I am using mine, and both exist in many places on the internet.

How can you know that the manufacturer for the speakers from the OP isn’t using the same definition that I am using?

BTW, when someone types "You’re out of your league," this typically indicates that they are at the limits of their own understanding and just don’t want to show their ignorance by pushing it further or are too head strong to consider another point of view.