8 ohm drivers

[audioholic 5,000+ posts]

Hey
Thanks for all the replies....why do I want to try that ? Well ...found OEM Dynaudio driver that is used in their HT subwoofer line and in the Totem Shaman speakers...they are awesome ...fast , tight and detailed....I'm not looking to break any SPL records...just trying to get a little bass to complement front stage...the only thing ...it's 8ohm ...but 90db should help a little..

Thanks

daRRski

Wait... what?
What exactly are you gonna do with those HT subs?

 

[TeoTorriatte 10+ year member]

If we are talking about 'headroom' then presumably you are discussing amplifier distortion output levels. And of course, lowering speaker impedance will inherently increase amplifier distortion output.
Headroom is good and all, but Id not recommend driving the amplifier to a lower impedance in an attempt to achieve it.

The difference in THD is inaudible (in the case of the Zapco), but the difference between clipping the signal or not most definitely will be audible.
But again, it all depends on the driver in question... if it's efficient enough, it may very well work. But I would just never recommend it as a method of reducing distortion.

 

[daRRski 10+ year member]

Hey

Trying to use it as a sub for my truck , single driver....friend of mine is trying to calculate the size of sealed box for it ...it will be powered with Zapco 500.1....bad idea ?

daRRski

 

[audioholic 5,000+ posts]

The difference in THD is inaudible (in the case of the Zapco), but the difference between clipping the signal or not most definitely will be audible.
But again, it all depends on the driver in question... if it's efficient enough, it may very well work. But I would just never recommend it as a method of reducing distortion.

THD generally doubles as impedance is halved. Whether or not doubling your THD will be audible would depend on what your initial THD threshold started at.
We were not comparing clipping to non-clipping, we were comparing 'headroom' to a system with none (but experiencing no clipping). The lack of headroom does not mean clipping is present.

 

[snouk dogg 10+ year member]

And how do we get an accurate spec on subwoofer efficiency to even consider? The 1khz spec manufacturers list? I dont think so. //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif
Don't assume an 8ohm driver is more efficient.

I know what he meant by 8ohm drivers are more efficient.

Click on the below topic and you'll understand a bit more how it usually is:

http://www.soundsolutionsaudio.com/forum/index.php?showtopic=7413

 

[audioholic 5,000+ posts]

I know what he meant by 8ohm drivers are more efficient. Click on the below topic and you'll understand a bit more how it usually is:

http://www.soundsolutionsaudio.com/forum/index.php?showtopic=7413

Sure, hypothetically speaking, an 8ohm driver can be more efficient. Being ohms does not make a speaker inherently more efficient than its 4ohm counterpart. Your link shows that when comparing specs at the same voltage, the difference in impedance can further confuse A/B comparisons of efficiency. The author chose to show two hypothetical speakers that, when the proper math is applied, the efficiency tables are actually turned. This does not mean 8ohm speakers are always more efficient. Multiply this confusion times the fact that most manufacturers rate subwoofer efficiency at 1khz, well above their usable bandwidth, and you have a real clusterfvck.

I stand by my statement that manufacturers rarely provide efficiency information on subwoofers that we can rely upon for any useful calculations.

 

[daRRski 10+ year member]

Hey

Here are some specs for this driver

240mm woofer 75mm voice coil

Imp. : 8 Ohm Fs Hz : 33 Qts : .84 Vas Ltrs : 88.2 Power Program Watts : 120 Efficiency dB 1W/1M : 90

Would this driver work in sealed box with Zapco 500.1 and not sound like a@@ ??

Thanks

daRRski

 

[helotaxi 5,000+ posts]

Ummm, headroom is a function of voltage which doesn't change between impedances. In all actuallity, headroom will be greater with the higher impedance driver. The amp will need to output less current for a given voltage output and is effectively overbuilt for that. As a result the power supply can more easily keep the voltage high. Factor in the typical higher better efficieny at higher impedance as well...both for the amp and driver. If you aren't trying to wring every last bit of power out of your amps, and if SQ is the goal this isn't an issue, then 8ohm drivers are an excellent option. Not to mention that most of the best pure sq drivers ARE 8ohm...

 

[IamDeMan 5,000+ posts]

Agreed. But voluntarily cutting your amps power output and eliminating several dB's of headroom isn't exactly everything either.
Obviously if the driver in question was quite efficient, it could work just fine. But I most certainly did not like the results of clipping when I tried it (even thought the driver I used had the response I was looking for)... the sound of a subwoofer clipping most definitely is not everything when it comes to audio.

Your general statement was still too much of a blanket. I never claimed using an 8ohm was a "be all" so your first statement was unnecessary. You saying "why would you want to" needed to be answered. Fact is that an 8 ohm driver may be suitable for some applications or people. What didn't work for you could be exactly what the next person is looking for.

 

[Electrodynamic 10+ year member]

Sure, hypothetically speaking, an 8ohm driver can be more efficient. Being ohms does not make a speaker inherently more efficient than its 4ohm counterpart. Your link shows that when comparing specs at the same voltage, the difference in impedance can further confuse A/B comparisons of efficiency. The author chose to show two hypothetical speakers that, when the proper math is applied, the efficiency tables are actually turned. This does not mean 8ohm speakers are always more efficient. Multiply this confusion times the fact that most manufacturers rate subwoofer efficiency at 1khz, well above their usable bandwidth, and you have a real clusterfvck.
I stand by my statement that manufacturers rarely provide efficiency information on subwoofers that we can rely upon for any useful calculations.

+1. Remember that new Massive Audio 15" "SQL" (or whatever it was) subwoofer rated at 101 dB? That measurement was taken with all 4 of the 1 Ohm coils in parallel. Do the math. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

High efficiency subwoofers aren't necessarily a good idea for car audio...especially if you're shoving it into a small box (probably small sealed). Here's another good read if your'e interested. But if you don't mind taking up your trunk with a box, then high efficiency subwoofers can produce a lot of output compared to their lower-efficiency counterparts.

IMO, I'd use that driver in a home audio application (what it was designed for), where you can have an enclosure that's of decent size.

*read* I'm not saying it won't sound good - I'm not saying that at all. What I am saying is that it might not go as low or play as loud as you hoped in a car because of the enclosure you may be putting it in (not to mention your cutting power considerably).

 

[audioholic 5,000+ posts]

Yep, efficiency in a subwoofer can actually be a bad thing in many situations. Hoffman's Iron Law... aint it a bitch. //content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif