Cab wiring question...

[manghu67]

Heya, gang...

Looking at picking up Hartke 410 Xl cab, but it is at 8 ohms and I want 4 ohms.

Checked Jumbo Sunshade's wiring diagrams, and they're 2, 8, and 16 ohms with four 8 ohm speakers, but no 4 ohms. The closest thing I've been able to find is this diagram from Crutchfield: http://a248.e.akamai.net/pix.crutchf...4-ohm_mono.jpg

If I use that diagram with 8 ohm speakers, it should give me a 4 ohm cab, right? Or am I going to blow something up? The bridge wires between the positive and negative terminals on each speaker have me confused.

If I could, I'd just wire the damn cab at 2 ohms and be done with it, but it's only rated at 400 watts and my amp pushes 450 watts with a 2 ohm load...

Advice please? Thanks!

[bassphase]

450 watts isn't any more likely to blow up your speakers at 2 ohms than 400 watts will. It's not enough difference. How stable is the amp pushing 2 ohms? You can actually blow up a speaker with not enough power if its distorting especially with a class D amp. I've done it a few times.

[Bass_Pounder]

It is not possible to wire an 8 ohm cab into a 4 ohm cab without replacing all the speakers - sorry !

[Bass_Pounder]

Originally Posted by bassphase

450 watts isn't any more likely to blow up your speakers at 2 ohms than 400 watts will. It's not enough difference. How stable is the amp pushing 2 ohms? You can actually blow up a speaker with not enough power if its distorting especially with a class D amp. I've done it a few times.

There is NO such thing as underpowering.

What you did was try to drive your amp too hard, and sent the cab peaks that were as high as twice your amps RMS rating.

[manghu67]

Amp is a Peavey Max450. It's rating:

450W @ 2 ohms
300W @ 4 ohms
170W @ 8 ohms

Two paralleled speaker jacks on the back.

Speakers in that cab are rated at 100W each, for a total of 400W. You're saying it's safe to push 450W through a 400W cab? I'd rather not be frying and replacing speakers constantly...

Originally Posted by bassphase

450 watts isn't going to blow up your speakers at 2 ohms any more than 400 will. It's not enough difference. How stable is the amp pushing 2 ohms? You can actually blow up a speaker with not enough power if its distorting especially with a class D amp. I've done it a few times.

[Bass_Pounder]

Originally Posted by manghu67

Amp is a Peavey Max450. It's rating:

450W @ 2 ohms
300W @ 4 ohms
170W @ 8 ohms

Two paralleled speaker jacks on the back.

Speakers in that cab are rated at 100W each, for a total of 400W. You're saying it's safe to push 450W through a 400W cab? I'd rather not be frying and replacing speakers constantly...

I run a 4 ohm cab rated at 600 watts with a head that is rated at 1,100 watts @ 4 ohms.

The rating of the head is only what it is CAPABLE of putting out, NOT what you will constantly be doing (unless you have the volume full throttle).

Listen with your ears, the speakers will tell you when they are in trouble, and then you need to ease off the volume knob or the low end EQ

[Bass_Pounder]

I should have added above:

The difference in wattage from your head running at 4 ohms vs. 8 ohms will only produce approximately +2db which is barely audible.

Best advice is to try using your cab as it is (8 ohms), and if you find it is not enough, then add another 4X10.

Volume comes from more speakers - not huge wattage.

[will33]

Get a pair of 8ohm 210's and stack them vertically instead. You'll have twice the dispersion and plenty of volume. Forget all this 2ohms/more power BS.

[billfitzmaurice]

Originally Posted by manghu67

Advice please?

Read this:
Pull ALL the watts

The bad news is you can't get a 4 ohm load. The good news is that you don't need it. Leave the cab alone.

[Sundogue]

Originally Posted by manghu67

Amp is a Peavey Max450. It's rating:

450W @ 2 ohms
300W @ 4 ohms
170W @ 8 ohms

Two paralleled speaker jacks on the back.

Speakers in that cab are rated at 100W each, for a total of 400W. You're saying it's safe to push 450W through a 400W cab? I'd rather not be frying and replacing speakers constantly...

That 400 watt cab is really displacement limited to only about 200 watts anyway. Displacement means how many useable watts it can handle. The wattage rating is just the thermal rating of the voice coils.

Don't worry about the wattage as it's rather meaningless. Unless you are cranking the amp full on, you aren't even putting probably 200 watts into the cab most of the time anyhow. Besides, the 400 watts is continuous whereas it can handle peaks (spikes from your playing) of 800 watts.

Still, don't pay attention to wattage. It's the displacement that matters and once you put about 200 watts into it the speakers will not go any louder and will let you know to turn it down by making the typical farting noises.

[RickenBoogie]

Huge +1 to post #7, #9, and post #10. In fact, re-read all 3 of them, for they speak the truth. Leave your cab as it is, add another if more volume is needed.

[BillyB_from_LZ]

Originally Posted by manghu67

... The closest thing I've been able to find is this diagram from Crutchfield: http://a248.e.akamai.net/pix.crutchf...4-ohm_mono.jpg

...

That diagram shows you how to take four speakers with dual 4 ohm voicecoils (DVC), make four 8 ohm speakers (by connecting the voicecoils in series) and then connect the speakers in parallel to make a 2 ohm system. No magic there.

[bassphase]

Originally Posted by Bass_Pounder

There is NO such thing as underpowering.

What you did was try to drive your amp too hard, and sent the cab peaks that were as high as twice your amps RMS rating.

I'd call that a textbook example of "underpowering". If it had more power it wouldn't have clipped and fried the speakers.

[Bassmec]

Originally Posted by bassphase

I'd call that a textbook example of "underpowering". If it had more power it wouldn't have clipped and fried the speakers.

Clipping does not of its self fry speakers, Volts combined with amps do.
Therefore there is no such thing as underpowering!
no matter how filthy your output, its all still just watts.
The melting point of copper is not waveform shape dependent. its a direct function of its resistance against total current flow, nothing else.

[billfitzmaurice]

Originally Posted by bassphase

I'd call that a textbook example of "underpowering". If it had more power it wouldn't have clipped and fried the speakers.

Clipping doesn't fry speakers. It's unimaginable how someone could be a member here for seven years and not be aware of that.

[manghu67]

Problem solved. Found a good used Peavey 412 TVX. 4ohms. It is a beast.

[manghu67]

I am pleasantly surprised at how musical this thing sounds. And it is LOUD.