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Four 4 ohm speakers = negative infinite impedance?

#4
to answer the original question, four 4Ω speakers in typical parallel ("hooked up together") would be 1Ω, nearly a dead short and pretty much a Bad Idea.
 
#5
walterw said:
to answer the original question, four 4Ω speakers in typical parallel ("hooked up together") would be 1Ω, nearly a dead short and pretty much a Bad Idea.
Click to expand...

Not to nit-pick, but he did say "speakers" not "cabinets". A typical 410 arrangement (for bass) is 2 series speakers connected in parallel to 2 more connected in series to get back to 4 ohms. But yes... 4 4 ohm cabs would be at 1 ohm and that would be bad for about 99.9% of the amplifiers out there.

Ox.
 
#8
Hi.

OxJohnson said:
What are the 1 ohm amps out there... When I was full of GAS I used to know of a couple, but I can't remember for the life of me and it is driving me nuts!!! I have a couple of 2 ohm stable amps, but this is driving me crazy!!!!

Ox.
Click to expand...

Any and all trasnformer coupled amps can have a 1 ohm tap wound to the OT if so desired. For no benefit though, but it is possible and IIRC I've seen a couple oldies wound like that.

On the SS side, there's none on MI/PA field that I can think of, but they're plentiful in car-audio circles.


Regards
Sam
 
#9
T-Bird said:
On the SS side, there's none on MI/PA field that I can think of, but they're plentiful in car-audio circles.
Click to expand...

Yeah, my old car was running the subs at 1 ohm, but man... I had to run 00 gauge wire for the power... that gets expensive!

I thought that there was a "true" 1 Ohm amp out there that was SS on the output, but I guess maybe not... hmmm... maybe a challenge for me to design one then?! 1 Ohm unto itself isn't that bad (if you cold guarantee it to be stable), it is the frequency impedance if it goes too much below that (impedance wise)! Right now I am building a capacitor bank for a test coil gun that can discharge into .05 ohms... but I know that is a stable DC load so I can spec everything to be safe.

Ox.
 
#10
i remember reading about a bizarrely big crown and a bizarrely big crest that would do 1Ω per side. by "big", i mean they were like 5 rack spaces tall and weighed hundreds of pounds.

the crown was called the macrotech 10,000, and i think it was mostly used for industrial applications or things like driving ultrasound machines.

for us musicians, plenty of power amps will do 2Ω per side, as long as there's enough wall current for them to draw and we don't let them get too hot. so 2 4Ω speakers (or cabs) per side is possible.
 
#11
Hi.

walterw said:
the crown was called the macrotech 10,000, and i think it was mostly used for industrial applications or things like driving ultrasound machines.
Click to expand...

Now that You mentioned it, I remember oogling at 'em not that long ago. Didn't notice the 1Ohm stability though since I was searching for 2Ohm stable amps, but it does make sense that those amps go that low. The price tag OTOH didn't make that much sense though ;).

Regards
Sam
 
#14
daaaaamn.jpg


you could maybe use it for bass on weekends then use it for arc-welding during the week :hyper:
 
#15
Hactar said:
The Macrotech 10000 is kinda an interesting amp.
Not only can it run 1Ω loads, Crown specs it at ~8000W into 0.5Ω. ONE HALF ohm loads!

Oh, and it's 6RU, 128lbs, and it eats 208V 3phase AC.
Click to expand...

The Macrotech 10,000 was really only used in big contracting applications like the sound system for the track at the Indy 500. Not saying some knucklehead didn't try to lug these around to drive a wall of ServoDrive subs or Community Leviathan boxes back in the day, but usually they would feed dozens of outdoor rated boxes or paging horns through low voltage designed commercial applications.

It would not be an interesting investment for your bass rigs or live rigs. You would not ever want to consider using this amplifier for any sort of practical live stage or main PA applications.

I've seen them, I've sold them, I've installed them. One simple two word phrase to conclude the discussion of this amp, "Move Along". And it wouldn't matter if your cousin knew a guy who worked at a prison that was closed and there was one of these driving the emergency horns in cell blocks and the yard......"Move Along". I put several in a major league sports venue to drive exterior paging horns/outdoor boxes and they crapped out on a regular basis. We replaced them with 3 two rack space 1,500W amps and had more poop and much more reliability.

But very much like a Peavey CS-800 also from a past era....they make awesome friggin' jack stands for your bus when you get a flat tire!!!

:eek:

walterw said:
daaaaamn.jpg


you could maybe use it for bass on weekends then use it for arc-welding during the week :hyper:
Click to expand...

You sir are understanding the true purpose of that amplifier!
 
#16
Keithwah said:
But very much like a Peavey CS-800 also from a past era....they make awesome friggin' jack stands for your bus when you get a flat tire!!!
Click to expand...
Say what you will about the CS-800, but I've got a couple of them in my rehearsal studio that are still kickin'. They are a bit noisy and they weigh a ton, but back in the day you couldn't beat them for Watts/$.
 
#19
yeah, but it looks like those insane power levels were only available at nearly dead-short conditions, like half an ohm.

at 4Ω, it actually had less power than a bridged RMX 2450.
 

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