• TalkBass has been independent since 1998. Add your voice.
    Create a free account to reply to discussions, view embedded media, and browse with fewer display ads.
    Join free Log in
    Want zero display ads or expanded classifieds tools? Compare plans.

How much volume lost using 8 ohms?

#4
i_got_a_mohawk said:
Comparing between two identical cabs (except for the fact one is 8ohms and one is 4ohms), you will loose just under 3 dB
Click to expand...
On paper, justing looking at the numbers, you'll probably lose about 1/2 your current volume.. however from experience, the BEST way to determine this issue is to A/B both cabs. And if you want to really get a measurable number on the differance, borrow a db meter or buy one from Rat Shack.
 
#5
Like the fist couple of posters said, not a huge loss of volume and certainly not half. Remember that you need ten times the power to double the volume. I have two 8ohm cabs but only use one most of the time (4x10) and it's normally plently loud with the volume well under half way (575W into 4, so about 300 into 8). IMO being able to position the cab well on stage is probably more important than the difference in maximum power.
 
#7
alexclaber said:
Just over 2dB. Figure in power compression (particularly mechanical power compression due to insufficient Xmax) and you can see why Euphonic Audio is ignoring those that believe they absolutely have to have a 4 ohm 4x10"! ;)

Alex
Click to expand...

Yeah I was gonna mention Euphonic Audio ... those line transmission cabs kinda bend the rules ... and in a good way.



:eek: ... A Euphonic Audio VL-208 should NOT be that loud and be only 16 x17 inches in size!
 
#9
As long as you are able to provide the speaker with half its rated power you won't lose anything, as no speaker will operate much beyond the half power point without the additional power being wasted as heat anyway. Going with a lower impedance cab is only an advantage if you've got an anemic amp to begin with.
 
#10
alexclaber said:
Just over 2dB. Figure in power compression (particularly mechanical power compression due to insufficient Xmax) and you can see why Euphonic Audio is ignoring those that believe they absolutely have to have a 4 ohm 4x10"! ;)
Click to expand...

Ignoring the phjilosophical "why should you need that many SPL" retorts, it makes good sense to offer larger cabs as 4-ohm loads (and smaller less capable cabs as 8 ohm loads so that when combined each driver is doing apprtoximately the same amount of work). If one desires, say, to more fully use their light power amp, and use more wattage instead of carrying two larger cabs to achieve this, they are evidently looking for less weight and less bulk - wanting to leverage the amp they purchased.

Provided the drivers/cab excursion capabilities are up to actually delivering it once bass frequencies are called upon, of course ; }

As for the twice as loud/soft thing, no way. TEN dB all other things equal would be twice as loud - and there is no way this scenario has 10 dB of extra SPL available. Provided the cabs could handle all the available power, and going from 450 to 750 watts, the 2.2 dB of extra output MIGHT be just enough to balance the local mix WITHOUT adding a cab.

...Though that's not much of a gain after driver power compression has taken from it, in some secenarios of amplifier wattage and cab handling abilities, changing from an 8-ohm load to a 4-ohm load could do appreciably better without making one haul another cab. It's always situational ; }
 
#11
billfitzmaurice said:
As long as you are able to provide the speaker with half its rated power you won't lose anything, as no speaker will operate much beyond the half power point without the additional power being wasted as heat anyway.
Click to expand...

A point most just don't get when looking at cab manufacturers' RMS specs without realizing that very few are using drivers that can actually handle the excursion that would demand. Thus the 2:1 power amp RMS to cab thermal rating often employed in sound reinforcement is not so usable for bass guitar cabs, save for making up for poor use of gain structure ; }

Going with a lower impedance cab is only an advantage if you've got an anemic amp to begin with.
Click to expand...

Or if you have an exceptional cab that could actually fully use more power than the amp can deliver at eight ohms, and an amp that can deliver enough power to actually drive it fully at 4 ohms. But usually with bass cabs this is not the case.
 
#12
greenboy said:
A point most just don't get when looking at cab manufacturers' RMS specs without realizing that very few are using drivers that can actually handle the excursion that would demand.
Click to expand...

Excursion is only half the story. The other half is thermal power compression within the motor structure. It's not the least bit unusual for a driver to have 3dB of power compression at full power, so even at frequencies where xmax is not exceeded you still won't get any more out of the driver at full power than you will at half power.
 
#15
GODSENT said:
this is an interesting thread. so what would be need between a 400watt head and an 800watt head. i am thinking dynamic reasons(greater articulation of eq) correct me if im wrong.
Click to expand...
Anything your head will deliver that's more than half the speakers rated power won't make it any louder, but the added headroom lets the amp work easier, with less potential for distortion on transient peaks and less heat build up in the amp, which is always a good thing. There are hi-fi guys who run 2,000 watt $10k Bryston amps into high efficiency speakers that never exceed ten watts draw. It's not any louder than a 20 watt amp, but it is cleaner, and if you consider $10k as chump change there's no reason not to do so. But you don't need to.
 

Latest posts

Top Bottom
Back