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Why 2 ohms is not a good idea..

#101
Actually, there is a simple answer. Ohms do not generate heat, watts do that. You need a cable adequate for the watts it will handle, regardless of how many ohms it sees.

Most of us will use multiple cabs to produce a 2 ohm load. Take note that if you daisy-chain the cabs the first cable carrys all the load. If you plug each cabinet directly to the head, the cables share the load, each cable only carrying the power for it's cab.

So for high power multiple cab rigs, plug each cab directly to the head.
 
#103
a4c2_3.jpg
 
#106
Big String said:
That makes sense Bill.

I not sure if I missed it on this thread or not but if running two cables to two cabs from one amp .. would it be beneficial if those cables were identical in length, gauge, and connector ?
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Only if you're OCD.
You need a cable adequate for the watts it will handle, regardless of how many ohms it sees.
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Cables are rated for voltage and current, not power. Current has resistance losses, voltage does not. With equal power the higher the voltage the lower the current, and the lower the cable insertion loss,which is why long AC transmission lines run at 100kV and more, and are stepped down in voltage as they near the destination. That's why they're still 440v on the pole outside your house. Lower impedance loads raise current, and that's what can cause problems in extreme cases, not power. In extreme cases, gentlemen.
 
#108
6 pages? Jeese! Im just saying IF the amp can do it, then it was designed to, if not..dont do it..I see way too many cats trying to get the most out of an amp and they start blowing stuff up...

too many bass amps in my repair shop to confirm this.

Now...whats this about Angelina Jolie? You know she's...umm...nekke' in Gia right?

Im building my own bass amp starting this weekend and might test it at 2 ohms, but I'll never run it at 2 ohms. I dont want to carry that size a speaker cable.
 
#113
It seems that a few people need to get a better understanding of Ohm's law in general before stating that a cable gobbles up "X" number of watts etc etc....

There are too many variables that would come into play before anybody can say anything about what is going on in a cable between any said amp and it's perceived load.
 
#116
the mojo hobo said:
Actually, there is a simple answer. Ohms do not generate heat, watts do that. You need a cable adequate for the watts it will handle, regardless of how many ohms it sees.
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I see where you can make this assumption but it is incorrect.

The reason we use larger cables for more power is for the CURRENT IN AMPS the cables need to carry.

Speaker circuits whether 2-4-8 or 16 ohms are low impedance circuits and need to have large cables carrying their current.

The limiting factor for VOLTAGE is the insulation capability on the wire. There is NO LIMITATION for POWER. In other words you can have a 20 ga wire handling 10,000 watts if the voltage is high and the current is low.

So when you lower the impedance of the circuit (speaker impedance) you increase the current in the circuit and need to respectfully increase conductor size to handle that current.

Resistance in the wire causes voltage drop across the wire (Power Loss) and that can be measured in voltage and then calculated in watts of power loss.

I hope this clears up some of the thinking here.

Where the monster cable BS hits is in the home stereo market. Even with 100 watt per channel amps and short cables you don't need over 14ga wires to your speakers.

In Bass apps with Kilowatt amps I feel a 12ga cable is not wasted copper in any length.

BOB
 
#117
ghiadub said:
I think that running at 1 ohm is not a good idea.

Running at 2 ohms is just me getting as many watts as I can out of my rig.
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WHY? Because you think it is just a bad idea? In the next few years you will be seeing new technology being developed in power amplifiers. Speaker loads in 1/2 ohm will probably be out in a couple years.

Speaker load impedance is just a number. A voice coil is JUST A DEVICE that has an impedance. Impedance is an AC circuit reactive component.

Yeah I highly recommend you don't plug your "Brand X" 8 ohm amp into a 1 ohm circuit, but these new Crown PA amps can handle 1 OHM easily. Eventually they will figure out how to handle the low impedances as cleanly as they do the high ones. Those amps do lose a little THD in the process, but you wouldn't know it in bass applications.

BOB
 
#118
chicago_mike said:
6 pages? Jeese! Im just saying IF the amp can do it, then it was designed to, if not..dont do it..I see way too many cats trying to get the most out of an amp and they start blowing stuff up...
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If you run a legit repair service and see a lot of blown amps I wonder if it is because they're low cost and have no protection?

The better designed amps have overcurrent (shortcircuit) protection.

Shorts happen. The amp should protect itself. Even if somebody inadvertently hooks up a wrong load, the amp should not self destruct.
 
#119
chicago_mike said:
All you guys who want 1200watts into a 2 ohm load...

I hope you know what you're asking.

1. You do know you lose 1/4 of your amps power thru the speaker cable itself right? Roughly 250watts..into nothing. You only lose 1/16th at 8ohms. We are talking speaker cable lengths less than 3 feet. And what happens if you blow a speaker? 2 Ohms is almost a dead short...NOT GOOD.

Dont use anything less than 10guage if your cable is over 1 foot in length. Yes..1 foot.

Think why your speaker cable gets warm..its a resistor.

2. your transformer has to be able to handle SAFELY over 2 amps consumption. 1 amp consumption is 450 watts. 2 Amp consumption is roughly 1200 watts.

I understand wanting more power..but its about clean SAFE power.

There are many more reasons, but I have seen so many posts about the intrest of high wattage low load output and I get concerned for the safety of my fellow lowenders.
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I think you are overstating your case here. Not only do many people (bass players and sound companies alike) run into 2 ohms every day, but people have been doing less for quite some time. McIntosh 2300s have a 1/2 ohm tap (1/4 ohm in bridged mono) and the Grateful Dead were running a bunch of these down to very low impedances in 1973 and 1974 with various versions of the wall of sound. I doubt very much they were running 10 gauge cable. They were fanatics about measuring stuff (who else measured the output of power tubes and their sensitivity to people smoking DMT? Not the musicians, mind you, but anyone in the room.) so I don't think this variable got by them. You can look up a lot of charts on various audiophile sites that will give guidelines on this that usually give a less than .5db of loss and it seems like 14 gauge wire will be perfectly adequate for runs of 10 feet or less. I use 12 gauge just because I can and with a 10 foot run and a 6 foot run and I have never felt any warmness at all. I run 2 ohms all night long with an iAmp 800.

So, do you have measurements to back up your theories? It seems like with the right equipment, this would be an easy argument to lay to rest. I would love to see them and am perfectly open to being proved wrong. In the meantime, I am going to use my amp as is.

Edwin
 

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