Mark Bass Amp/Cab: Resistance question

[JLG]

Okay, so I've never been able to get my head around ohms and resistance, so please be gentle.

 

I have these:

• Mark Bass Little Mark IV 300W Bass Head

• Mark Bass MB58R 102 ENERGY 400W 8 Ohm 2x10 Neodymium Custom Speakers Bass Cabinet

  • The specification for this cabinet says impedance is 4 ohms, 8 ohms

 

Here is the dumb question: in this setup, is the impedance 4 ohms or 8 ohms?

Here is another dumb(er) question: if it is 4 ohms, is the output 150 watts?

 

Dumb question number 3: If I add a Mark Bass MB58R 151 ENERGY 400W 8 Ohm 1x15 Neodymium Custom Speaker Bass Cabinet to this in series (the bass head has one output), will the resistance be 8 ohms and the output be 300 watts?

 

Thanks in advance.

[Mykesbass]

Looking at that spec sheet, I'm thinking that the cab was available in either 4 or 8 ohms. It should say on the plate which yours is.

[simonlittle]

6 minutes ago, Mykesbass said:

Looking at that spec sheet, I'm thinking that the cab was available in either 4 or 8 ohms. It should say on the plate which yours is.

Good point. Assuming you do indeed have the 8ohm cab, you’d be currently getting 150W with that setup. You’d need to add a second 8ohm cab to get the full 300W out of your amp

[obbm]

In  answer to question 3 the experts always recommend using identical cabinets i.e. get another 2 x 10 not pair your 2 x10 with a 1 x 15.

[pete.young]

53 minutes ago, JLG said:

 

Here is the dumb question: in this setup, is the impedance 4 ohms or 8 ohms?

Here is another dumb(er) question: if it is 4 ohms, is the output 150 watts?

 

Dumb question number 3: If I add a Mark Bass MB58R 151 ENERGY 400W 8 Ohm 1x15 Neodymium Custom Speaker Bass Cabinet to this in series (the bass head has one output), will the resistance be 8 ohms and the output be 300 watts?

 

 

1) It will be one or the other, depending on whether you buy a 4 ohm cab or an 8 ohm cab.

 

2) No. Cabs don't have an output. 150W is usually quoted as the maximum amount of power that an cabinet can recieve before thermal damage to the voice coil occurs. In practice it is usually less than this before the sound becomes distorted.

 

3). Cabs like this are wired in parallel, not series. If you connect your amp to a 4 ohm cab and then daisy chain the second 8 ohm cab you will end up with an overall load of around 2.6 ohms. I would recommend that you don't do this, because a load less than 4 Ohms is likely to cause damage to the amp. If both cabs are 8 Ohm, the overall load is 4 ohm which is within the specification of the amp.

[Chienmortbb]

49 minutes ago, pete.young said:

No. Cabs don't have an output

Strictly speaking cabinets output acoustic power and while it would be possible to state the power in watts, it would not make good reading for the marketeers.

[JLG]

2 hours ago, simonlittle said:

Good point. Assuming you do indeed have the 8ohm cab, you’d be currently getting 150W with that setup. You’d need to add a second 8ohm cab to get the full 300W out of your amp

Thank you.

The 102 is an 8 ohm cab so it appears I'm getting 150 watts.

[JLG]

1 hour ago, obbm said:

In  answer to question 3 the experts always recommend using identical cabinets i.e. get another 2 x 10 not pair your 2 x10 with a 1 x 15.

Why shouldn't I pair it with a 1x15?

On the Markbass website, the 151 "can be used as a standalone ... or in combination with a MB58R 102 ENERGY", which I have.

 

[JLG]

 

The MB58R 102 is 8 Ohms.

The Little Mark IV has two speaker outputs (image below):

1. SPEAKON / 1/4”COMBO JACK
2. 1/4” JACK

More dumb questions:

• Do I connect them in series, or parallel?
• If in parallel, is it safe to use both outputs (one for each cabinet)?

Thanks again.

[Chienmortbb]

23 minutes ago, JLG said:

Why shouldn't I pair it with a 1x15?

On the Markbass website, the 151 "can be used as a standalone ... or in combination with a MB58R 102 ENERGY", which I have.

 

I was at the World Headquarters of a well known boutique speaker maker the other day and an experiment was tried. Two identical cabinets, one loaded with a single 10. The other loaded with the same model 10 plus a properly crossed over horn/compression driver cab, FRFR if you like. 

Although the cabinets and bass drivers were identical, the sound with two of them was far from good. Louder yes but with there were some weird artefacts that took your attention away from the music and onto the speakers.

 

A similar  thing will happen when mixing 10s and 15s. The 10s will go higher than the 15 and the 15 will beam more meaning the sound will change as you go off axis. In addition, if the impedances are different the power will not be evenly distributed between the drivers so the total gain in volume may be less than expected.

[obbm]

36 minutes ago, JLG said:

Why shouldn't I pair it with a 1x15?

On the Markbass website, the 151 "can be used as a standalone ... or in combination with a MB58R 102 ENERGY", which I have.

 

Member Bill Fitzmaurice should be able to explain exactly why.

Edited August 18 by obbm

[simonlittle]

39 minutes ago, JLG said:

Why shouldn't I pair it with a 1x15?

On the Markbass website, the 151 "can be used as a standalone ... or in combination with a MB58R 102 ENERGY", which I have.

 

I’ve never heard that you have to use matching cabs. A 1x15 and 2x10/4x10 is a classic combo and should give you a good range. I also have the 102 Energy and a 104 Energy. Just make sure they’re both 8ohm cabs. And I’d wire them in series…

Edited August 18 by simonlittle

[simonlittle]

…plus In the past I had a 1x15 and 4x10 Warwick setup and that sounded glorious. Both 8ohm cabs. 

[itu]

4 minutes ago, simonlittle said:

I’ve never heard that you have to use matching cabs. A 1x15 and 2x10/4x10 is a classic combo...

It was. It is not acoustically nor electrically the best solution. But things and knowledge was also different in the 80's.

 

And once again: wattage is not about loudness. dB is. If you have two identical amps, the other set to 150 W output, and the other to 300 W output, the difference in loudness is 3 dB. You can just hear this. If you want more, like 10 dB more, you need to multiply the power output by 10, to 1500 W. Hearing is logarithmic, not linear.

[JLG]

4 minutes ago, itu said:

It was. It is not acoustically nor electrically the best solution. But things and knowledge was also different in the 80's.

 

And once again: wattage is not about loudness. dB is. If you have two identical amps, the other set to 150 W output, and the other to 300 W output, the difference in loudness is 3 dB. You can just hear this. If you want more, like 10 dB more, you need to multiply the power output by 10, to 1500 W. Hearing is logarithmic, not linear.

 

Okay, so if I combine the following, what will the loudness be?

• Mark Bass Little Mark IV 300W Bass Head
• Mark Bass MB58R 102 ENERGY 400W 8 Ohm 2x10 Neodymium Custom Speakers Bass Cabinet

And what will the loudness be if I add this in parallel?

• Mark Bass MB58R 151 ENERGY 400W 8 Ohm 1x15 Neodymium Custom Speaker Bass Cabinet

[itu]

@JLG : loudness should be measured. It cannot be guessed from the data companies publish in their web pages. This is sad, but Marketing sections have decided watts are of interest, not loudness.

[Chienmortbb]

On 18/08/2024 at 14:20, JLG said:

 

Okay, so if I combine the following, what will the loudness be?

• Mark Bass Little Mark IV 300W Bass Head
• Mark Bass MB58R 102 ENERGY 400W 8 Ohm 2x10 Neodymium Custom Speakers Bass Cabinet

And what will the loudness be if I add this in parallel?

• Mark Bass MB58R 151 ENERGY 400W 8 Ohm 1x15 Neodymium Custom Speaker Bass Cabinet

It is possible that mixing cabs would work well but as our Americans friends would say "it's a crap shoot". Two cabs will be louder and likely to produce more low end but they will also produce some odd response to a greater or lesser degree.

 

Just to muddy the water further, as @itu said, the real measure of loudness is dB and it is the measurement of Sound Pressure Level. The two cabinets mentioned have quoted sensitivities of 101dB and 100dB respectively BUT the crucial thing is that no indication of the methodology. The usual way to measure it is feeding the speaker with 1 Watt and measure at a distance of 1 metre. If we take the 15", it is only available in an 8 ohm version. 100dB sensitivity is at the high end of sensitivity for a 15" speaker. It is possible but unlikely.

 

The 2x10 can be either 4 or 8 ohms and if they measure the 4 ohm cab, they may have used the "trick" of feeding a 4 ohm cab with a higher voltage*. It means that the cabinet would appear almost 3dB louder.

 

It's all marketing smoke and mirrors.

 

*2.8 volts, the voltage used to obtain 1 watt into an 8 ohm load. That gives almost 2 watts or another 3dB.

 

Edited August 19 by Chienmortbb

[Lozz196]

I’ve had a good few 210/115 set ups, all worked well, but in all cases the resulting sound of both cabs together was different than from either cab in its own.

 

I’ve also had setups with 2 of the same cab and this worked much better, as essentially you get a good sound with one cab then double it. No changes to eq etc. 

[jrixn1]

22 hours ago, JLG said:

The Little Mark IV has two speaker outputs (image below):

1. SPEAKON / 1/4”COMBO JACK
2. 1/4” JACK

More dumb questions:

• Do I connect them in series, or parallel?
• If in parallel, is it safe to use both outputs (one for each cabinet)?

 

22 hours ago, simonlittle said:

And I’d wire them in series…

 

Regarding connections, you have two options:

1. connect amp to cab1; and then cab1 to cab2
2. connect amp to cab1; and then the amp's other output to cab2.

However both are electrically equivalent and result in parallel wiring.  Wiring cabs in series is very uncommon (because there isn't really a benefit) and you'd have to go out of your way to get the necessary special box or cables.

[Bill Fitzmaurice]

22 hours ago, itu said:

@JLG Marketing sections have decided watts are of interest, not loudness.

Consumers are as much to blame as marketeers in that. You can see examples of that with every post where someone comments about 'getting all the watts out of my amp'. Being professional musicians we should all have at least a rudimentary understanding of how the tools of our trade work, but sadly most do not. That could be excused when all we had to go by was manufacturer sales brochures, but that hasn't been the case for the last two decades. The truth is out there, a simple search will find it.