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JonJT
12-25-2005, 01:54 AM
I'm looking for a midrange to bridge the bap between a CD1pro mini body and a Koda 8. The CD1's sensitivity is rated at 101 dB and the Kodas is rated at 86db, both at 1W,1m. Although, the nominal impedence of the horns is 8 ohmns and the Kodas is 4 ohmns.

I'm looking for a midrange driver with a sensitivity rating of at least 90 db (also 1W,1m) into either 4 or 8 ohmns.

Also, producing the same wattage into a higher nominal impedance requires more voltage, no? Therefore, producing a certain intensity of sound at 4 ohmns would require more power than at 8 ohmns? So when compairing the sensitivities of 2 woofers rated at differen nominal impediances, you have to take into account that you will actually be using more current when using the 4ohmn speakers? Right? If this is that case, then could someone please explain how it will effect level matching?

Eugenics
12-25-2005, 01:56 AM
seas

springy101
12-25-2005, 01:56 AM
i think its the other way around cuz when you run an amp at 8 ohms it runs a lot cooler than at 4 ohms.

JonJT
12-25-2005, 02:01 AM
seas
I have seen no SEAS woofers with the right combination of extension, cone area, excursion and sensitivity that I need. The L18RNX/P would be perfect if the sensitivity was higher.

JonJT
12-25-2005, 02:02 AM
The Audax PR170M0 would probably be perfect (maybe even a little to perfect), but it is no longer made.

squeak9798
12-25-2005, 02:03 AM
I'm looking for a midrange to bridge the bap between a CD1pro mini body and a Koda 8. The CD1's sensitivity is rated at 101 dB and the Kodas is rated at 86db, both at 1W,1m. Although, the nominal impedence of the horns is 8 ohmns and the Kodas is 4 ohmns.

I'm looking for a midrange driver with a sensitivity rating of at least 90 db (also 1W,1m) into either 4 or 8 ohmns.


http://zalytron.com/

Audax PR170M0

[/thread]

:D

Winslow on ECA had some for sale recently also that you may wish to check into.


Also, producing the same wattage into a higher nominal impedance requires more voltage, no?


More voltage, less current.

100w into 8ohms;

sqrt(100*8) = 28.28V

100w/28.28V = 3.54A

28.28*3.54 = 100.1w (not exactly 100w due to rounding)

100w into 4ohms;

sqrt(100*4) = 20V

100w/20V = 5A

20*5 = 100w


Therefore, producing a certain intensity of sound at 4 ohmns would require less power than at 8 ohmns? No, so when compairing the sensitivities of 2 woofers rated at differen nominal impediances, you have to take into account that you will actually be using more power when using the 8ohmn speakers? Right?

Not sure I follow. How would you get more power with 8ohm?

Also, that doesn't take into account things such as power compression, etc. Just because a 4ohm speaker will receive more power, doesn't mean it will ultimately be louder.


If this is that case, then could someone please explain how it will effect level matching?

Sure.....just do it either by ear or an RTA, as that's what really matters :)

squeak9798
12-25-2005, 02:04 AM
Oh, yeah...forgot about the not being made thing :( Not sure if Zaly has any in stock or not. But check and see if Winslow still has his. If not, PHL has a cousin to the Audax that would work wonderfully....albeit more expensive than the Audax.

JonJT
12-25-2005, 02:05 AM
i think its the other way around cuz when you run an amp at 8 ohms it runs a lot cooler than at 4 ohms.
I kinda contradicted myself there. The greater the impedance, the higher the voltage and the lesser the current. I just don't know how this plays into compairing the sensitivities of woofers that have different nominal impedance ratings.

JonJT
12-25-2005, 02:12 AM
It seems that the Audax woofers are no longer in stock. I'll check for the PHL woofers.

Just fiddling with some algebra, it seems that for a constant input voltage the lower impedance woofers will receive m ore current, thus, more power. Hmmm, thinking about how I can manipulate amp input sensitivity and level matching with this in mind is........fun. Kinda makes me think that rated sensitivity means little.

JonJT
12-25-2005, 02:18 AM
Errrrr, are those PHL woofers going to have the displacement needed to keep up woth the Kodas and ID horns?

squeak9798
12-25-2005, 12:31 PM
Errrrr, are those PHL woofers going to have the displacement needed to keep up woth the Kodas and ID horns?

Midrange doesn't require large displacement to get loud like midbass and subwoofers. Even if you took a large excursion driver, like an Extremis, and played it as a pure midrange....it would use barely any of it's excursion and stay within the +/- ~.5mm range. For horns, large cone area and high sensitivity alone are what to look for in a good pure midrange.

The Audax, for example, only have .5mm Xmax. They just won't get low in frequency....the Audax can't go much below 175hz on a steep slope. But they'll play the midrange frequencies with more than ample output. On the other hand something like the Extremis (for example) can play lower in frequency due to it's large excursion.

squeak9798
12-25-2005, 12:42 PM
It seems that the Audax woofers are no longer in stock. I'll check for the PHL woofers.

Just fiddling with some algebra, it seems that for a constant input voltage the lower impedance woofers will receive m ore current, thus, more power. Hmmm, thinking about how I can manipulate amp input sensitivity and level matching with this in mind is........fun. Kinda makes me think that rated sensitivity means little.

Remember, that doesn't take into account things like power compression and such.

Yes, in theory if you take two drivers of the same sensitivity and supply one twice the power, it will have 3db more output. Heck, take a pair of the exact same drivers and send one twice as much power and you should theoretically see a 3db gain. What you aren't testing is the validity of sensitivity. What you are testing is the affect of power on acoustical output. Does that mean senstivity is meaningless? No, it means power applied will change the output level.....which is a pretty obvious conclusion.

And things aren't perfect in the real world like that. Except for when possibly dealing with very low wattage (jumping from say 1w to 2w), you'll almost never see an actual 3db increase in output when doubling power. Just because the 4ohm driver is receiving more power it doesn't mean 1) the 4ohm driver can handle that extra power, and 2) that the 4ohm driver will absolutely have more output.

I guess the point I'm getting at......if you have ample power @ 8ohm, than that's all that matters. If you have an 8ohm driver and don't have enough power, pick up a more powerful amplifier.

Also be sure you are comparing apples to apples. Some 4ohm drivers still have sensitivities rated at 2.83V rather than 1w, which means you'd need to subtract 3db from the rated sensitivity.

JonJT
12-25-2005, 01:33 PM
Alright then, The midrange woofers will probably be low passed around 300-400hz. I guess I'm looking for a 6.5inch woofer that has the "pressence" or "in your face" sound that some CD1pro horns and Koda 8s are going to provide.

squeak9798
12-25-2005, 02:26 PM
You mean highpassed around 300-400hz?

Anyways....both the Audax and the PHL will give you that :)

JonJT
12-25-2005, 07:27 PM
Yes, highpass. THanks for the recomendations.