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Switchable 4 ohm, 8 ohm Cabinet

#21
Am I correct in thinking, that with his 375 watt at 8 ohm, and 600 at 4 ohm, when he adds another identical 8 ohm cab, he will get 600 watts, but that 600 watts will be split between the two cabs, thus giving him 300 watts per cab? I think alot of us get fooled into thinking that BOTH cabs are pumping out 600 watts.
 
#22
jnewmark said:
Am I correct in thinking, that with his 375 watt at 8 ohm, and 600 at 4 ohm, when he adds another identical 8 ohm cab, he will get 600 watts, but that 600 watts will be split between the two cabs, thus giving him 300 watts per cab? I think alot of us get fooled into thinking that BOTH cabs are pumping out 600 watts.
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This is correct. However, the 8ohm power level is typically a bit more than half (i.e., you don't typically double the power from 8 to 4). With amps like the Shuttle, its more like 375 watts into 8ohms, and 600 into 4.

That's why most find that using two identical, small 8 ohm cabs works great with these 500 or so watt micro's if you want a modular system, or one large 4ohm cab (like a 212 or 410) works great when you prefer a single cab solution and play at relatively high volumes.
 
#23
I had thought I would get the full wattage in any 4 ohm cabinet.. and then have the wattage (600) split between two cabinets @ 8 ohms apiece.. all I was wanting was a cabinet that would not ALWAYS have to be used alone.. the shuttle 12 seems nice, but I don't care for its EQ section at all.. it's just too flexible for me (yes, I despise too much EQ options.. The shuttle 6.0 is about all I can handle).. above, a poster is claiming if I grab a 4 ohm cabinet, I won't notice much of an increase.. I would have thought a 4 ohm 4x10.. or something like El Whappo would yield a huge sound--in one cabinet.. @ 4 ohms.. having the full 600 watts of the Shuttle..

However, I currently, again, have two 12" cabinets.. I can sell the Bergantino for a profit, which is crazy.. as I bought it used.. so I was thinking of selling it and buying another cabinet, not the 12" GB extension.... and having it be either 4 or 8 ohms.. that way, for one show, I could use it by itself.. for another use it paired with the 12T cabinet.. ah, too many options.. Maybe I should have bought just a power amp, and kept using the sansamp..
 
#24
Blah114 said:
I had thought I would get the full wattage in any 4 ohm cabinet.. and then have the wattage (600) split between two cabinets @ 8 ohms apiece.. all I was wanting was a cabinet that would not ALWAYS have to be used alone.. the shuttle 12 seems nice, but I don't care for its EQ section at all.. it's just too flexible for me (yes, I despise too much EQ options.. The shuttle 6.0 is about all I can handle).. above, a poster is claiming if I grab a 4 ohm cabinet, I won't notice much of an increase.. I would have thought a 4 ohm 4x10.. or something like El Whappo would yield a huge sound--in one cabinet.. @ 4 ohms.. having the full 600 watts of the Shuttle..

However, I currently, again, have two 12" cabinets.. I can sell the Bergantino for a profit, which is crazy.. as I bought it used.. so I was thinking of selling it and buying another cabinet, not the 12" GB extension.... and having it be either 4 or 8 ohms.. that way, for one show, I could use it by itself.. for another use it paired with the 12T cabinet.. ah, too many options.. Maybe I should have bought just a power amp, and kept using the sansamp..
Click to expand...



See my posts in this thread for more detail. The 4ohm versus 8ohm thing can be trivial or VERY impactful, depending on many different things. Beware those saying that it either doesn't matter or that it's extremely important regardless of context.

http://www.talkbass.com/forum/showthread.php?t=514722
 
#26
jnewmark said:
Am I correct in thinking, that with his 375 watt at 8 ohm, and 600 at 4 ohm, when he adds another identical 8 ohm cab, he will get 600 watts, but that 600 watts will be split between the two cabs, thus giving him 300 watts per cab? I think alot of us get fooled into thinking that BOTH cabs are pumping out 600 watts.
Click to expand...

For the love of............whatever...........WHY??????????

Why would anyone think that? Do they not teach arithmetic any more in school? Basic Science? Nada?

Sorry........... rant over.

:hiding:
 
#30
JustDavid said:
I might be alone in this opinion, but I feel there are FAR more important areas cabs & drivers could be enhanced. Excursion, heat dissipation, efficiency, total mass . . .
Click to expand...

I agree. The 4ohm to 8ohm thing was always a bit of a 'holy grail' back in the day when most SS amps would not function safely below 4ohms. Now, it seems like this idea is a 'day late and a dollar short'.

My guess is, you won't see the Epi's even go into production.
 
#31
DukeLeJeune said:
I happened to have some of test equipment out, so before posting this I ran the T/S parameters on two woofers in series vs the same two in parallel. The variation in Qes, Qms, and Qts came to about 1%, which is within the margin of error for my test equipment. This data refutes the JBL paper. I knew it would, because I manufacture two loudspeaker systems that use series-wired drivers and I'm familiar with their measurements.

Now, adding a resistor in series with a voice coil will definitely raise the system Q, and in my opinion is almost never a good idea. But series connection of identical woofers will not. And I have the data to prove it:

Parallel connection (8-ohm woofers): Qes = .551; Qms = 2.87; Qts = .471
Series connection (8-ohm woofers): Qes = .547; Qms = 2.81; Qts = .468

While we're at it, just for fun:

Single 8-ohm woofer: Qes = .543; Qms = 2.83; Qts = .455
Single woofer w/8-ohm series resistor: Qes = 1.30; Qms = 2.87; Qts = .893
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Interesting. Thanks for shedding some light on this. That 1% variation is really negligible and I doubt that 99.9% of people would be able to hear that. I'm surprised how much a dummy load raised the Qes and Qts values, about 200% that's quite a bit.


DukeLeJeune said:
Bluedyna, assuming your amplifier delivers double the wattage into the 4-ohm load resulting from adding a second identical 8-ohm cab, you'd get a net increase of 6 dB in output. This breaks down as follows: 3 dB from the doubling of power, and 3 dB from the doubling of air displacement (from having twice the cone area). To be precise, this applies to frequencies where the two drivers are less than 1/4 wavelength apart; as we go up in frequency from this point, there will be progressively more and more destructive interference between the drivers and as a result up there they'll sum to less than the theoretical 6 dB increase.
Click to expand...
Yup. He beat me to it.



KJung said:
Epifani did throw out a 'test balloon' at NAMM of cabs with dual voice coil speakers that could be switched from 8 to 4ohms. There's no indication yet if they will actually put them into production.
Click to expand...
Really? Cool. I didn't know this. All my good ideas always come to me just after someone else decides to try them. However, I'd be interested to see the switching circuit they used.
 
#33
for the record (or CD).. I never thought 600 watts would be, apiece, dispersed into each 8ohms cab.. what I am wanting, is all 600 watts to get into 1 4 ohms cab.. right now, I use two 8 ohms cabs.. and it's 300 watts per cabinet dispersed.. or whatever the specs are..

Also, here is an e-mail response from Epifani:

"(Dual Impedance Speaker Tecnology) series that we introduced at the 2009 Namm show this year (we were awarded from Bass Gear Magazine as the most inovative product of the year) is in fact switchable from 8 ohm to 4 ohm. The D.I.S.T. comes in a 410 version, 210, 115, and 112."

Whether they are available or not, I do not know.. but I will wait and keep what I have until this all gets sorted out.. someone, somehow, will figure this out.. and the above cabs from Epifani will likely cost $5,000 or some insane amount for the first 5 months.. then they will have bugs people will discover.. so I will wait like 1.2 years until AFTER Epifani releases the switchable cabinets.. where there is a will , there is a way.. and I will not likely soon get rid of my Shuttle 6.0.. it's just too easy to play with.. and requires next to no tweaking.. it really is an amazing, stunning, piece of gear.. if it could just pump out 2,000 watts into stadium sized cabinets that each weighed 5lbs.. I would be set..

but until then, it will be two cabinets for all shows.. the shuttle's 12T cabinet can no way handle by itself a small bar unless it has house sound.. and even then, I would have to lay down to hear it entirely.. with a 5-piece band.. but with two cabinets @ 300 Watts apiece, it's thunderous, nearly.. add an active bass, like my sterlie sounding Modulus, and the roof blows off the club..

Thanks for the Markbass cab information, and other information.. next... someone will release a cabinet that can 8,4, or 2.. or why don't these guys all get together and agree 4 ohms is the standard.. release only 4 ohms cabinets.. and then have heads can do two, three, four, or one 4 ohm cabs? And don't get me started on Speakon connectors.. :) Make the standard 4 ohms.. and leave it @ that.. or 2.. but can someone tell me why some cabs are 8, others 2.. then others 4.. and I have even seen some that claim to be 6 ohms.. I am not an audio engineer.. so if I sound like a kid that knows nothing, I apologize.. the choices for bass players are many.. for that I am grateful--and confused.
 
#36
Blah114 said:
for the record (or CD).. I never thought 600 watts would be, apiece, dispersed into each 8ohms cab.. what I am wanting, is all 600 watts to get into 1 4 ohms cab.. right now, I use two 8 ohms cabs.. and it's 300 watts per cabinet dispersed.. or whatever the specs are..
Click to expand...

I think you still might be a bit confused. Two 8ohm 112's is, for all practical purposes, identical to one 4 ohm 212.

What most of us do is get our small cabs in 8ohm configuration, since you can use one at lower power, and two to get full power out of most solid state heads. For large (i.e., multidriver cabs) that can actually use and benefit from more wattage, I get those in 4ohm version. Perfect.

If you want to combine a small cab with a large cab, you still really should combine a small 8ohm cab with a large 4ohm cab, which results in more even distribution of power to each driver (e.g., an 8ohm 210 and a 4ohm 410 combined results in am impedance of 2.67 ohms, and results in a solid state head delivering the same power to each of the 6 drivers). If you had a 'switch' on the 410 to change it to 8ohm, then the 210 and 410 would be getting the same amount of power, which means double the power to the two drivers in the 210. This doesn't make a lot of sense.

It is better to think of power delivered per driver, not cabinet.

Hope that makes sense.

K
 
#37
Fab_Superlative said:
Yes,that is correct.

That is why I threw it out here for discussion.
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I believe what he's saying is that it is NOT an impedance switch. It just changes the cab from a single 4ohm 810 to two 8ohm 410's in the same box. That's a totally different thing, and MB does not market this as an impedance switch. I believe the big SWR 810 is wired the same way.

It actually works the opposite of what you would really want, and what an impedance switch would really do (i.e., 8ohms with the combined 810, and 4 ohms for stereo operation into each half of the cab... think what configuration the original Eden WT800a or the new Genz Shuttle 12 Max would run at full power). Not sure what good going the other way around would do anyone.
 
#38
KJung said:
I think you still might be a bit confused. Two 8ohm 112's is, for all practical purposes, identical to one 4 ohm 212.

What most of us do is get our small cabs in 8ohm configuration, since you can use one at lower power, and two to get full power out of most solid state heads. For large (i.e., multidriver cabs) that can actually use and benefit from more wattage, I get those in 4ohm version. Perfect.

If you want to combine a small cab with a large cab, you still really should combine a small 8ohm cab with a large 4ohm cab, which results in more even distribution of power to each driver (e.g., an 8ohm 210 and a 4ohm 410 combined results in am impedance of 2.67 ohms, and results in a solid state head delivering the same power to each of the 6 drivers). If you had a 'switch' on the 410 to change it to 8ohm, then the 210 and 410 would be getting the same amount of power, which means double the power to the two drivers in the 210. This doesn't make a lot of sense.

It is better to think of power delivered per driver, not cabinet.

Hope that makes sense.

K
Click to expand...


Perfect sense.. so if I get a 4 ohm cabinet, I can still pair it with my 8 ohm.. thanks.. what I have been most confused about.. I was thinking the 4 ohms would not at all work.. that it would be just dead. However, it would be nice to have a larger cabinet, like a 2x12 take the entire output of the Shuttle.. and I guess what you're saying is the 4 ohm cabinet would do both..
 
#39
Blah114 said:
Perfect sense.. so if I get a 4 ohm cabinet, I can still pair it with my 8 ohm.. thanks.. what I have been most confused about.. I was thinking the 4 ohms would not at all work.. that it would be just dead. However, it would be nice to have a larger cabinet, like a 2x12 take the entire output of the Shuttle.. and I guess what you're saying is the 4 ohm cabinet would do both..
Click to expand...

Correct. An amp doesn't 'know' the difference between a 4ohm cab and two 8 ohm cabs.

However... CAREFUL. All the amp 'cares about' is the total nominal impedance. A 4ohm 212 cab can work great with the same brand and design 8ohm 112 (or three 8ohm 112's) IF that amp can run safely at an impedance of 2.67 ohms (which happens with an 8 and 4ohm cab, or three 8 ohm cabs).
 
#40
KJung said:
Correct. An amp doesn't 'know' the difference between a 4ohm cab and two 8 ohm cabs.

However... CAREFUL. All the amp 'cares about' is the total nominal impedance. A 4ohm 212 cab can work great with the same brand and design 8ohm 112 (or three 8ohm 112's) IF that amp can run safely at an impedance of 2.67 ohms (which happens with an 8 and 4ohm cab, or three 8 ohm cabs).
Click to expand...

I am not sure a Shuttle 6.0 can do that.. honestly. I don't think so, according to the specs.
 

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