Bi-amp or extension cab?

[Tommy TGrip]

I have a Rumble 500c which is 350 watts on its own at 8 ohms. I need a bit more and I am on the lookout for an extension cab. But, I also have a GK MB10 which is 100 watts. Both cabs have 10 inch speakers (210 and 110). A splitter would be far cheaper than another cab. Any advice on bi-amping generally, and using these two combos specifically? I'm interested in how the wattage difference, and 10s would work together. There's an Orange Amp Detanator A/B/Y pedal near me that's priced to sell. Cheers

 

[Tommy TGrip]

Sorry, follow up question. Any advice on using effects with this set up also appreciated. I think I will do this. The 110 sits nicely on the Rumble and it'll be fun.

 

[jnewmark]

Bi-amping needs to be done with a crossover. What you are doing is running two rigs at the same time.

 

[JRA]

I have a Rumble 500c which is 350 watts on its own at 8 ohms. I need a bit more and I am on the lookout for an extension cab. But, I also have a GK MB10 which is 100 watts. Both cabs have 10 inch speakers (210 and 110). A splitter would be far cheaper than another cab. Any advice on bi-amping generally, and using these two combos specifically? I'm interested in how the wattage difference, and 10s would work together. There's an Orange Amp Detanator A/B/Y pedal near me that's priced to sell. Cheers

@jnewmark is correct. you're really contemplating "two channels" and that can work out really well with some planning and experimenting with the equipment you already have, e.g.:

i occasionally use two amps (powering two or more cabs) and one 'system'/channel is used for the EFX signal chain while the other is set up to be an EFX-less, regular bass signal. i don't always need that firepower so i mostly use a typical rig (one amp, one cab) but i think my two-channel rig is the best/coolest rig i have and i love the opportunities to use it. when my EFX are not being used = two amps, each powering a cab(s), each getting the same signal from the instrument.

i split the EB signal at my pedal board. it's nice to have EFX when i want them while always having that uncompromised bass at the same time.

you can do the same! good luck with your two-channel bass rig!

 

[Michedelic]

Sorry, follow up question. Any advice on using effects with this set up also appreciated. I think I will do this. The 110 sits nicely on the Rumble and it'll be fun.

What effects are you running? Are you planning on using both amps at the same time constantly, as opposed to kicking in the 1x10 occasionally as an extra push over the cliff, so to speak?

 

[Wasnex]

Ideally you want to run speakers that are specifically designed to work together. No guarantees that a GK will work well with a Fender.

If there is a matching cab for the Rumble, I think that would probably be the best option, but it can depend on the sensitivity ratings of the speakers, which AFAIK are not published for the Rumble series.

With matching cabs, when you double the drivers the sensitivity rating goes up about 3dB.

The impedance also is cut in half, which has often has an impact on the amount of power a solid-state amp can produce.

With 8 ohms the Rumble makes up to 350W and with 4 ohms the Rumble makes up to 500W.

Decibel Difference from Increased Power = Log(500/350) x 10 = 1.5dB.

Total Calculated dB Increase 3dB + 1.5dB = 4.5dB. This is a noticeable increase in SPL

Since the GK provides it's own power, it will not reduce the volume of the Rumble. But I don't expect a 110 powered by 100W to make a lot of difference, although it may...IMHO try it and judge for yourself.

To help you understand how it works:

When you have two identical cabs tight packed together and playing at the same level, you get approximately +6dB from acoustic summing. In other words if both cabs are producing 90dB individually, the combined output is about 96dB. Maximum acoustic summing occurs for frequencies where driver spacing is less than about 1/4 wavelength...I.E. at low frequencies, which have longer wavelengths.

If the cabs are not identical they may not integrate well. Essentially they fight at some frequencies rather than working together. This is do to differences in group delay and phase angle.

If the SPL of one cab is 3dB lower than the other, acoustic summing gives you about +4.6dB over the SPL of the loudest cab. For example 90dB and 87dB = ~94.6dB

If the SPL of one cab is 6dB lower than the other, acoustic summing gives you about ~+3.5dB.

If the SPL of one cab is 10dB lower than other, acoustic summing gives you about ~+2.4dB.

We generally assume you need at least a 3dB change to clearly hear a difference. With a 10dB volume differential between the two cabs, you may not notice any benefit from adding the 110.



I used this web calculator for the acoustic summing estimates: Total dB level adding of coherent correlated sound sources combining decibels or SPL sound pressure level audio logarithmic decibel scale loudspeaker add signal noise levels incoherent noncoherentt - sengpielaudio Sengpiel Berlin

 

[Tommy TGrip]

@jnewmark is correct. you're really contemplating "two channels" and that can work out really well with some planning and experimenting with the equipment you already have, e.g.:

i occasionally use two amps (powering two or more cabs) and one 'system'/channel is used for the EFX signal chain while the other is set up to be an EFX-less, regular bass signal. i don't always need that firepower so i mostly use a typical rig (one amp, one cab) but i think my two-channel rig is the best/coolest rig i have and i love the opportunities to use it. when my EFX are not being used = two amps, each powering a cab(s), each getting the same signal from the instrument.

i split the EB signal at my pedal board. it's nice to have EFX when i want them while always having that uncompromised bass at the same time.

you can do the same! good luck with your two-channel bass rig!

Thanks

 

[Tommy TGrip]

What effects are you running? Are you planning on using both amps at the same time constantly, as opposed to kicking in the 1x10 occasionally as an extra push over the cliff, so to speak?

I'd run both at all times. FX are minimal. A compressor and overdrive - Darkglass Alpha Omega pedal. I thought I might run comp into both, and maybe overdrive into the 1 X 10 only. The Rumble has it's own OD, so would go light touch into the GK and could kick more in through the Rumble when needed.

 

[Tommy TGrip]

Ideally you want to run speakers that are specifically designed to work together. No guarantees that a GK will work well with a Fender.

If there is a matching cab for the Rumble, I think that would probably be the best option, but it can depend on the sensitivity ratings of the speakers, which AFAIK are not published for the Rumble series.

With matching cabs, when you double the drivers the sensitivity rating goes up about 3dB.

The impedance also is cut in half, which has often has an impact on the amount of power a solid-state amp can produce.

With 8 ohms the Rumble makes up to 350W and with 4 ohms the Rumble makes up to 500W.

Decibel Difference from Increased Power = Log(500/350) x 10 = 1.5dB.

Total Calculated dB Increase 3dB + 1.5dB = 4.5dB. This is a noticeable increase in SPL

Since the GK provides it's own power, it will not reduce the volume of the Rumble. But I don't expect a 110 powered by 100W to make a lot of difference, although it may...IMHO try it and judge for yourself.

To help you understand how it works:

When you have two identical cabs tight packed together and playing at the same level, you get approximately +6dB from acoustic summing. In other words if both cabs are producing 90dB individually, the combined output is about 96dB. Maximum acoustic summing occurs for frequencies where driver spacing is less than about 1/4 wavelength...I.E. at low frequencies, which have longer wavelengths.

If the cabs are not identical they may not integrate well. Essentially they fight at some frequencies rather than working together. This is do to differences in group delay and phase angle.

If the SPL of one cab is 3dB lower than the other, acoustic summing gives you about +4.6dB over the SPL of the loudest cab. For example 90dB and 87dB = ~94.6dB

If the SPL of one cab is 6dB lower than the other, acoustic summing gives you about ~+3.5dB.

If the SPL of one cab is 10dB lower than other, acoustic summing gives you about ~+2.4dB.

We generally assume you need at least a 3dB change to clearly hear a difference. With a 10dB volume differential between the two cabs, you may not notice any benefit from adding the 110.



I used this web calculator for the acoustic summing estimates: Total dB level adding of coherent correlated sound sources combining decibels or SPL sound pressure level audio logarithmic decibel scale loudspeaker add signal noise levels incoherent noncoherentt - sengpielaudio Sengpiel Berlin

Thanks, I'll have a close look at this. Much appreciated

 

[Pulverizor]

Just plug an instrument cable into the Rumbles FX send and into the GKs front.
Keep the GKs input pad on and gain low for a start.

 

[Tim Skaggs]

As has been explained, using two amps isn’t the exact definition of “bi-amping”, but at least the core of a bi-amp rig and core of a two-amp rig are much the same.

As @Wasnex explained very well, a speaker designed to be used with the Rumble is probably the best outcome possible, but I know that requires $$, so here’s my thoughts;

You can try using both amps to see if it helps at all for no $$. You can even do a poor-man’s bi-amp rig by rolling off the bass and boosting the treble &/or mids on the GK, and let it handle mostly mids & highs while you EQ the Rumble as you normally do. It looks like you have to go in to the GK at the normal input jack, no effects return jack or power amp in jack available.

Here are a couple possible ideas and problems that might occur.

• Split signal from the bass running to both amps: this should work ok, but putting effects in the signal path going to just one amp could create a problem. Some effects flip polarity when engaged. You don’t want the two amps out of phase or you will lose all bottom end and generally have a crappy sound.

• Coming out of the effects send of the Rumble and going in the input of the GK while your bass goes only to the input of the Rumble. This can work, but you will want to engage the -10db pad on the GK input and start with the gain very low to avoid distortion from preamp stacking. You can still put effects between the Rumble & the GK so only has the GK has effects, but you still have to be aware of a polarity reversal. This is how I run my GK 500 MB into my GK MB 112e, but I have to make sure the limiter on the GK is not engaged, because it flips the phase of the 112e. This method requires an extra shielded cable to run from the Rumble effects out to the input of the GK, so it’s about as cost free as it gets.

Happy experimenting.

 

[Tommy TGrip]

Just plug an instrument cable into the Rumbles FX send and into the GKs front.
Keep the GKs input pad on and gain low for a start.

Yeah I have considered this. As you probably know, the GK doesn't have an effects loop, otherwise I would use that, probably from the GK to the Rumble. I'd be interested in other's views on this as well. Cheers

 

[Zooberwerx]

You've got it...use it. I'd just slave or split using the G&K MB. If it truly sounds bad, snag an ext. cab for the Rumble. Not sure where you're located in Australia but stuff is inordinately expensive.

Riis

 

[Tommy TGrip]

You've got it...use it. I'd just slave or split using the G&K MB. If it truly sounds bad, snag an ext. cab for the Rumble. Not sure where you're located in Australia but stuff is inordinately expensive.

Riis

Yep, in Australia. Crazy expensive. Like sometimes stuff comes up on Facebook marketplace and you think "gee whiz, that's a good price" and then as you're clicking on it you realise it must be a USA ad that's made it through. New stuff is expensive. Second hand stuff is expensive too