Amp Cab Setup

[Josh Garcia]

I just purchased a Little Mark iv 300w amp and the mark bass mb58r 102 pure bass cab 4ohms. I just realized the amp is rated at 8 ohms. Did I make a mistake in not buying an 8 ohm cab

 

[Josh Garcia]

So quick update, guitar centers website, where I purchased the head, said the output power is “300W RMS @ 8ohm/150W RMS @ 8ohm”. But the MarkBass website says “Minimum ohm load for all Markbass heads is 4 ohms”. I don’t know anything about this stuff, are these two sources telling me different things?

 

[BlueP]

the 4ohm will deliver 300 and the 8 ohm 150

If you requested a 4ohm, I would ask GC if they could swap it.

the other option is that you could purchase another MB 8 ohm and when you need to use
the extra cabinet, you then get to the 300 rms at 4 ohms

but if the one cabinet serves your purpose then enjoy that.

 

[Josh Garcia]

the 4ohm will deliver 300 and the 8 ohm 150

If you requested a 4ohm, I would ask GC if they could swap it.

the other option is that you could purchase another MB 8 ohm and when you need to use
the extra cabinet, you then get to the 300 rms at 4 ohms

but if the one cabinet serves your purpose then enjoy that.

So the head puts out 300w at 8ohms, the cab is a 400w 4ohm, I have no plan to add another cab as it’s for home use and maybe a small bar for open jams, is that setup fine?

 

[BlueP]

So the head puts out 300w at 8ohms, the cab is a 400w 4ohm, I have no plan to add another cab as it’s for home use and maybe a small bar for open jams, is that setup fine?

Yep, that’s a good set up. enjoy

 

[Chris Chong]

So the head puts out 300w at 8ohms, the cab is a 400w 4ohm, I have no plan to add another cab as it’s for home use and maybe a small bar for open jams, is that setup fine?

Don’t worry, it’s fine.

 

[Wasnex]

@Josh Garcia

Specs for the Little Mark IV from GC

• Output power: 500W RMS @ 4 ohm, 300W RMS @ 8 ohm

MB58R 102 ENERGY 2x10

• • Power Handling (AES Standard): 400W RMS

You said the speaker is 4 ohms. This means the amp can make up to 500W. The amp is safe with one 4 ohm cab, but you cannot add another cab. If you want to run two cabs, trade the 4 ohm cab for an 8 ohm cab. Two 8 ohm cabs in parallel = 4 ohms.


The amp can make more power than one cab can handle. So you need to use a bit of discretion to avoid blowing the cab. The cab does have a high sensitivity rating (101dB), so it should produce quite a bit of volume.

Calculated SPL at 400W with one cab = [Log(400) x 10] + 101 = 127dB. If you focus more on mids, this cab should be capable of meeting your needs, unless you play stupid loud. However, if you prefer huge lows, it will probably not be able to meet your needs.

When you add a matching cab, the sensitivity goes up approximately 3db, impedance is cut in half, and power handling doubles.

Calculated SPL of two 8 ohm cabs with 500W = [Log(500) x 10] + 104 = 131dB.

So two 8 ohm cabs will be able to play approximately (131 -127 =) 4dB louder than one 4 ohm cab.

Also with two matching cabs in parallel, power is shared equally. So each cab will receive up to (500/2=) 250W which is well below the 400W power rating.

 

[abarson]

I just purchased a Little Mark iv 300w amp and the mark bass mb58r 102 pure bass cab 4ohms. I just realized the amp is rated at 8 ohms. Did I make a mistake in not buying an 8 ohm cab

@Wasnex there appear to be 3 different models all bearing the same name.
From the Little Mark IV manual:
OUTPUT POWER
300W RMS @ 4 ohm, 150W RMS @ 8 ohm
(LITTLE MARK IV 300)

500W RMS @ 8 ohm, 300W RMS @ 4 ohm
(LITTLE MARK IV/LITTLE MARK IV COMBO)

1000W RMS @ 4 ohm, 600W RMS @ 8 ohm
(LITTLE MARK IV NINJA)

@Josh Garcia The only "mistake" is that you won't be able to add a second cabinet if and when you need more volume. If it's not too late, I'd see if you could exchange the 4 ohms cabinet for an 8 ohms version.