4X12 cab ohm experts HELP please....

[rodrigo_echeverri]

Re: 4X12 cab ohm experts HELP please....

Originally posted by Denis:
I just bought a randall head with an 8ohm cab, would I connect the cab to the 4ohm jack on the head?

<font size="2" face="Verdana, Helvetica, sans-serif">Denis, do you mean, you dont have an 8 ohm output on the randall head?... if you have an 8ohm output there, that is the way to go... if you don't then, like said before, the cabinet will work connected to the 4 ohm output of the head without blowing up but the sound won't be optimal.

[Chuckracer]

Re: 4X12 cab ohm experts HELP please....

This impedence mismatch we are talking about is ONLY suitable for TUBE heads and amps.

Solid state stuff is WAY less tolerant of impedence mismatches and you probably WILL blow it up with a mismatch.

And a lower impedence WILL cause your tubes to run hotter/wear faster. Years of expirence, son. I'm not talking roach em fast, but maybe take a couple of months life off them.

[ April 25, 2003, 01:42 PM: Message edited by: Chuckracer ]

[rodrigo_echeverri]

Re: 4X12 cab ohm experts HELP please....

Originally posted by Chuckracer:
This impedence mismatch we are talking about is ONLY suitable for TUBE heads and amps.

<font size="2" face="Verdana, Helvetica, sans-serif">Is the Randall he is talking about a solid state?... sorry, then you are right chuckracer...

Originally posted by Chuckracer:
And a lower impedence WILL cause your tubes to run hotter/wear faster. Years of expirence, son. I'm not talking roach em fast, but maybe take a couple of months life off them.

<font size="2" face="Verdana, Helvetica, sans-serif">Ok, but do you think they sound better or the same when you run the a BIT hotter?

[Chuckracer]

Re: 4X12 cab ohm experts HELP please....

Personally, I don't care for the mismatch sound in either direction, but that's just my taste.

[OnlineStageGear]

Re: 4X12 cab ohm experts HELP please....

"Ok, but do you think they sound better or the same when you run the a BIT hotter?"

If you want um to run harder, slam the front end of the amp where you have more control.

Matt

[Denis]

Re: 4X12 cab ohm experts HELP please....

theres 2 jacks that arent labelled 4 or 8ohms, theyre just black and it says minimum 4 ohm. what do i hook the 8ohm cab to if theyre unlabelled?

[Chuckracer]

Re: 4X12 cab ohm experts HELP please....

This is solid state or tube?

[Denis]

Re: 4X12 cab ohm experts HELP please....

its a solid state

[rodrigo_echeverri]

Re: 4X12 cab ohm experts HELP please....

Originally posted by OnlineStageGear:
"Ok, but do you think they sound better or the same when you run the a BIT hotter?"

If you want um to run harder, slam the front end of the amp where you have more control.

Matt

<font size="2" face="Verdana, Helvetica, sans-serif">Sorry Matt, I don't know what you meant???...

Denis: Please tell exactly what you have... model and everything.

[ April 25, 2003, 06:03 PM: Message edited by: rodrigo_echeverri ]

[Denis]

Re: 4X12 cab ohm experts HELP please....

randall rh200 head

[rodrigo_echeverri]

Re: 4X12 cab ohm experts HELP please....


In very simplified terms, in the circtui above, the resistor represents your cabinet and the voltage source your power amp. If the impedance goes down, then the current flowing in the circuit goes up (from the equation there)... you see, equipment doesnt like by any means to go above its current rating. When you connect a lower impedance than you need, then the system is called a BBQ.

In Denis case, his backplate says "Minimum 4 ohms" because anything larger than that wont draw enough current to fry the circuit...

[ April 25, 2003, 06:21 PM: Message edited by: rodrigo_echeverri ]

[rodrigo_echeverri]

Re: 4X12 cab ohm experts HELP please....

Denis,

This is the manual you need:

http://www.randallamplifiers.com/war...rg75_rh100.pdf

It pretty much tells how impedance affects your power rating and so on... it seems you head has an optput that says "minimum 4 ohm" and one that says "minimum 8 ohm"... just dont go below those numbers and you will be fine.

Keep in mind that even though the impedance mismatch wnot make fireworks the rating fot eh head will be affected a bit... but very little though. Look at page 3 in the specifications table and you will see how the things spits out more power when you use the 4 ohm load...

[OnlineStageGear]

Re: 4X12 cab ohm experts HELP please....

Since an Ohm meter reads Resistance, and speakers are rated with Impedence, you will not always get an exact reading. Plus, an 8 Ohm speaker is usually not right at 8 ohms anyways. The 7.1 of resistance you are reading basicly will tell you you have an 8 ohm cab.

Take your Ohm Meter and put the 2 test leads together, that should read 0.00 letting you know your meter is accurate.

Matt