CHANGING 4 OHM CAB INTO 8 OHM ONE :( help ?

[Jitterboy]

Basicully i have two Trace Elliot bass cabs:

1048H old

Wattage - From what i guess is around 300 watt as some idiot scratch out the information at the back.

Ohm - measured it to be 8 ohms.


1524

Wattage - 400 watt

Ohm - 4 ohm.


And a Trace Elliot GP12 SMX ( 280 watt - rms )

Which has two, 8 ohm outputs at the back.


Is there anyway i can change the ohm of the 1524 to 8 ohm ? I have heard the suggestion of using a matching transformer to change the ohm from 4 to 8 but can't find one that can handle the 400 watts from the cab any help would be extreamly appreciated

[type C basses]

Impedance is determined by the drivers (speakers) in the cab. You have wattage output (W) at a certain rated impedance (N), then you have the impedance of the cab(M). Then do this...
W*(N/M)=Watts being fed into each speaker. Make sure your speakers are rated to handle the heat. These figures seem to get convoluted by manufacturers to sell 'higher powered' equipment.

To answer you question more directly, to double the impedance, double the speaker count. Your other option would be to split the speakers and have two separate input jacks, one for each amp channel. There are arguments for and against doing this. I hope someone more knowledgeable than I comes through for you soon.

EDIT: Scratch that last part. Backwards math, lol! 2 Ohm speakers?

[bongomania]

^^^ Lolwut?


It's very, very simple. The 1524 is a 2x15 cab. Get two 16 ohm 15's and wire them in parallel.

Forget the transformer, that would be a massive waste of effort and energy for no benefit.

[type C basses]

Originally Posted by bongomania

^^^ Lolwut?

I'm obviously still learning this stuff. Can you tell me which part of what I said is incorrect? Obviously the second paragraph is WAY off, but isn't the first part on track?

[EpiRipper]

Originally Posted by type C basses

Impedance is determined by the drivers (speakers) in the cab. You have wattage output (W) at a certain rated impedance (N), then you have the impedance of the cab(M). Then do this...
W*(N/M)=Watts being fed into each speaker. Make sure your speakers are rated to handle the heat. These figures seem to get convoluted by manufacturers to sell 'higher powered' equipment.

To answer you question more directly, to double the impedance, double the speaker count. Your other option would be to split the speakers and have two separate input jacks, one for each amp channel. There are arguments for and against doing this. I hope someone more knowledgeable than I comes through for you soon.

EDIT: Scratch that last part. Backwards math, lol! 2 Ohm speakers?

Going by this logic with my rig:
watts (W) = 1100
at a certain rated impedance (N) = 4 ohms
the impedance of the cab(M) = 2 x 8ohms in parallel = 4 ohms
W*(N/M)= 1100(4/4) = 1100Watts being fed into each speaker which I can assure you would cook each and every speaker in my rig... so totally wrong.

The scond part of your statement about doubling the impedance by doubling the speakers all depends on how they are wired... in series will double the impedance ie: 2 x 4 ohms = 8 ohms... in parallel it will halve the impedance 2 x 4 ohms = 2 ohms

[type C basses]

Originally Posted by EpiRipper

Going by this logic with my rig:
watts (W) = 1100
at a certain rated impedance (N) = 4 ohms
the impedance of the cab(M) = 2 x 8ohms in parallel = 4 ohms
W*(N/M)= 1100(4/4) = 1100Watts being fed into each speaker which I can assure you would cook each and every speaker in my rig... so totally wrong.

The scond part of your statement about doubling the impedance by doubling the speakers all depends on how they are wired... in series will double the impedance ie: 2 x 4 ohms = 8 ohms... in parallel it will halve the impedance 2 x 4 ohms = 2 ohms

Thank you! It's so simple if you know what the heck you're talking about.

[GregShadoan]

Originally Posted by bongomania

^^^ Lolwut?


It's very, very simple. The 1524 is a 2x15 cab. Get two 16 ohm 15's and wire them in parallel.

This might be easier said than done. I was hunting for some medium grade 15" @ 16ohms, and they are hard little devils to find. Finally gave up and went with a series wiring instead.

[walterw]

why on earth would you want to make a 2x15 cab into an 8Ω cab? that will just cause any amp you plug into it to not produce as much power, making for a weaker sound.

PA and bass drivers are 8Ω each for a reason, and two big ones in one box are just about always wired to be 4Ω for a reason.

[EpiRipper]

Originally Posted by walterw

why on earth would you want to make a 2x15 cab into an 8Ω cab? that will just cause any amp you plug into it to not produce as much power, making for a weaker sound.

PA and bass drivers are 8Ω each for a reason, and two big ones in one box are just about always wired to be 4Ω for a reason.

I would say it's so he can use it together with his 8 ohm 4X10

[type C basses]

Originally Posted by EpiRipper

I would say it's so he can use it together with his 8 ohm 4X10

Wow! Totally missed that before. I thought he was trying to replace his old cabinet with the new one, not use them both.

[walterw]

i suspected as much, from another thread about the amp.

he's barking up the wrong tree, and won't gain anything useful by this.

instead of spending money to ruin his 2x15 cab, i'd suggest wrangling a separate power amp.

(actually, i'd recommend not bothering with running a 2x15 and a 4x10 at the same time, but that's a different argument.)

[Munjibunga]

The short answer to the OP's question is no, unless he wants to swap drivers. It can't be done with the existing drivers.

[larryshaw48]

just educate yourself about Ohms Law (to original poster) and rmember taht Resistance measured at speakers is not the impedence.

[daveh30]

EDIT: *nevermind, not gonna open that can of worms. no sense making it sound more complicated than it actually is....