BassmanPaul

Calculating parallel impedances is so simple as just about every one in the world has a calculator built into their phone. Formula is R1 times R2 divided by R1 plus R2. Using 8Ω and 4Ω: 4Ω times 8Ω=32, 8Ω plus 4Ω = 12. 32 divided by 12 = 2.67Ω. QED

Back in the late Seventies I used an H&H scoop twin 15. That was supplanted by a 'stereo' system with a 15" JBL K145 and two TL style cabinets housing JBL K120 12" drivers on each side of the stage. The amp was a SS 200W per side amp that I had designed for the purpose. The pre-amp was my build too. The whole shebang weighed a ton but sounded wonderful. The best part was the amplifier worked first time I powered it on. YEAH! I still own the power amp and it still works. Today I use a 2000W capable Class D power amp pushed by a simple tube pre-amp I again designed for the job. That drives either two or four Acme B2 2x10 three way boxes and I've never been happier.

Looks to me that the amp chassis has ventilated spacers on each side of the amp. Have you taken the amp out of the combo and taken a look?

@Thor please don't forget to keep us up to date with how you find the amp.

Swine!! I would really like one of those.

The cabinets are best if they are identical. If they are of different manufacturers do the battery test and ensure they are both working with the same polarity.

@ZenBasses how are you getting on with your amplifier?

Not all fans are created equal. If you want to replace the fan first check the specs of the installed unit.

A thought that struck me was are the two cabinets working with the same polarity. If one is 'pushing' whilst the other is 'pulling' they are going to fight each other all night long, and that's not a cue for a song!

Maybe the amp doesn't like your playing! I hope you can get your problem sorted.

I don't think that a SansAmp has enough output to drive the power amp properly. It depends on the input sensitivity of said amp. The SansAmp was designed to work into the normal input of a bass amp therefore instrument level.

I know but to be accurate the formula is 1/RTotal =.1/R1 + 1/R2 LOL

Not wanting to argue with you but if your main cab is 8Ω and you try to add a second cab that is 4Ω to a 4Ω minimum amplifier what is going to happen? I was trying to pass on information to someone who may not understand impedances. I wanted to keep matters simple.

An other thing about using a Series box is that you will not get all the power out of the amp that it's capable of. The amp will see 8Ω and thus will give less than it's 4Ω level of 800W. When buying an amplifier to use with your existing speaker cabinets it's wise to consider their impedances and verify that the amplifier is capable of driving them safely.

As for this Palmer box I wouldn't use it. It only has 1/4" phone sockets that are not safe to use with a high power solid state amp. SpeakOns are the only way to go for this service. All you need is a plastic box and three NL4 SpeakOn sockets. If you want to build such a box I'll tell you how to wire it.

I use 4Ω Acme B2 2x10 cabinets and I run them one per channel of a class D power amp. It works well.

Having items stuffed in your ears becomes a necessity after reaching a certain age in this business. My hearing is permanently damaged by playing music. my latest pair of hearing aids cost me $6000 plus. They help but I dislike them intensely. Putting transducers in my ears is less irritating trust me!!

May I humbly suggest that you practice with something else at home?

I have to admit that I find the complaints about fan noise strange. I simply pay no attention to it.

@Open E did my last suggestion help?

What I term my small PA has a 1KW Class D power amp, a Mackie mixer and an IEM transmitter with five receivers. When I'm using it my bass amp with it's Acme two ten drivers becomes my subwoofer. It works well but I much prefer the 'openness' of my bass amp doing its thing. To each their own.

just for interest, what will a sub do for bass guitar. The lowest note on a bass would be around 30Hz. That's above where a sub will typically operate.

My standard tip in such cases is if the amp has and effects loop connect Send and Return with a signal cable. Same goes if the amp has a Pre-amp Out and a power amp in sockets.

The pairing of a 4x10 and a 1x15 is poor at best. Often it leads to the demise of the 15. Thinking that a larger cone equates to more bass is antiquated thinking. The 4x10 is more than capable of putting out more lows than a single 12 or a 15.

It pleases me to see a person who has been dragged up proper like!!