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-   -   changing ohmage on 2x10 cabinet (http://www.talkbass.com/forum/f15/changing-ohmage-2x10-cabinet-1021970/)

 monkeybass68 10-11-2013 12:53 PM

changing ohmage on 2x10 cabinet

I've got a 2x10" cab that's wired to 4 ohms. It has 2 - 8 ohm speakers. Can someone tell me how to I wire it to 16 ohms (so I can run it parallel with another 4 ohm cabinet & make rig run at 8 ohms)?

 Bass_Pounder 10-11-2013 12:58 PM

Connecting a 16 ohm cab to a 4 ohm cab will NOT give you an 8 ohm load (it will be under 4 ohms).

 LowEZ 10-11-2013 12:59 PM

BUT... running a 16ohm cab with a 4 ohm cab will NOT give you an 8 ohm load!

 JTE 10-11-2013 01:02 PM

A 16 ohm load in parallel with a 4 ohm load is 3.2 ohms. Formula for parallel impedance is (R1xR2)/(R1+R2). That's (16x4)/(16+4) = 64/20 = 3.2.

And, "ohmage" is NOT a word. You want to know how to change the impedance.

John

 Bass_Pounder 10-11-2013 01:02 PM

Quote:
 Originally Posted by LowEZ (Post 14980713)
That is a series connection.

You could easily use the diagram to make a "series speaker cable", and use both of your 4 ohm cabs together.

Just solder 1/4 jacks where the speakers are in the diagram.

 BassmanPaul 10-11-2013 01:05 PM

if you have two 4Ω cabinets they need to be run in SERIES to produce an 8Ω load. This will require a special cable. If both of the cabinets contain a crossover you might run into some difficulties if they interact poorly.

No matter what Wicki says there is no such word as "Ohmage" the word is Impedance.

 LowEZ 10-11-2013 01:06 PM

Quote:
 Originally Posted by Bass_Pounder (Post 14980729) That is a series connection - not parallel.
That is correct. He wanted two 8 ohm speakers to give him 16 ohms.

 Bass_Pounder 10-11-2013 01:08 PM

Quote:
 Originally Posted by LowEZ (Post 14980743) That is correct. He wanted two 8 ohm speakers to give him 16 ohms.
Ouch !

I really need to read better myself :D

I'll edit my other post.

 P Town 10-11-2013 01:10 PM

If you look a the diagram posted by LowEZ, but change each speaker to a speaker cabinet, the impedance of each cab will add to become the total load. If each cab is four Ohms, you will have them wired in series, and you will have an eight Ohm load. If both cabs have speak-on connectors it is very easy to wire the speaker cable this way. Make sure to confirm that the speakers are all moving in the same direction in unison, by applying a nine volt battery to the input cable, and observing that the cones all move in, or out. If they don't, reverse the connections at one cabinet.

 JTE 10-11-2013 01:17 PM

Quote:
 Originally Posted by P Town (Post 14980767) If you look a the diagram posted by LowEZ, but change each speaker to a speaker cabinet, the impedance of each cab will add to become the total load. If each cab is four Ohms, you will have them wired in series, and you will have an eight Ohm load. If both cabs have speak-on connectors it is very easy to wire the speaker cable this way. Make sure to confirm that the speakers are all moving in the same direction in unison, by applying a nine volt battery to the input cable, and observing that the cones all move in, or out. If they don't, reverse the connections at one cabinet.
But you can't simply connect two cabinets together and get a series load. Every speaker cabinet I've had experience with (since ca. 1975) have the jacks wired in parallel. Physical appearance means nothing, it's all about how it's wired. You will need a special series speaker cable.

John

 flatfender 10-11-2013 01:28 PM

Here's a couple of TB threads with pics on how to make series cables and/or boxes

http://www.talkbass.com/forum/f15/se...-cable-881561/

http://www.talkbass.com/forum/f30/th...o-cabs-709619/

 P Town 10-11-2013 01:52 PM

Quote:
 Originally Posted by JTE (Post 14980799) But you can't simply connect two cabinets together and get a series load. Every speaker cabinet I've had experience with (since ca. 1975) have the jacks wired in parallel. Physical appearance means nothing, it's all about how it's wired. You will need a special series speaker cable. John
I was not trying to say you could just plug a standard speaker cable from one to the other. It requires a series wired speaker cable. That is what the drawing shows. It is showing two speakers, but if you substitute a speaker cabinet for each speaker shown in the drawing you have a pair of speaker cabinets wired in series. Think about the connections at each speaker as the input jack to the speaker cabinet. Notice that the polarity is positive to negative. Wire the cable up with a temporary connection, and do the battery test to ensure all the speakers move in, or out in unison, and then solder it.

 monkeybass68 10-11-2013 06:27 PM

Thanks for all the info guys. I'd just like to clarify one thing though. If I do indeed re-wire this 2x10 to be 16 ohms, would it still be safe to run it parallel with a 4 ohm cab (i.e. run amp to jack of 4 ohm cab and other jack of 4 ohm cab to the 16 ohm cab)?
Many times over the years I've run 8 ohm cabs that way and never had impedence problems with my amps. Only time I've had problems was running a 4 ohm cab & 8 ohm cab together (which I did over 20 years ago & I blame on being young & ignorant).

 SunnBass 10-11-2013 06:46 PM

Simply put: DO NOT RUN CABS OF MIXED IMPEDANCE.
Forget this idea of a 4 ohm cab and a 16 ohm cab at the same time.
It is the same "mistake" as when you ran that 4 ohm and 8 ohm cabinet 20 years ago.

 ggunn 10-11-2013 06:58 PM

Quote:
 Originally Posted by monkeybass68 (Post 14982075) Thanks for all the info guys. I'd just like to clarify one thing though. If I do indeed re-wire this 2x10 to be 16 ohms, would it still be safe to run it parallel with a 4 ohm cab (i.e. run amp to jack of 4 ohm cab and other jack of 4 ohm cab to the 16 ohm cab)? Many times over the years I've run 8 ohm cabs that way and never had impedence problems with my amps. Only time I've had problems was running a 4 ohm cab & 8 ohm cab together (which I did over 20 years ago & I blame on being young & ignorant).
A 4 ohm cab and a 16 ohm cab in parallel will give you about a 3.2 ohm total load and most of the sound will come out of the 4 ohm cab. If both cabs are 4 ohm two speaker cabs, I recommend wiring them both internally in series to make them each 16 ohms, and then running them in parallel for an 8 ohm total load. Your amp will thank you.

 Vince Klortho 10-11-2013 07:03 PM

Quote:
 Originally Posted by monkeybass68 (Post 14980690) I've got a 2x10" cab that's wired to 4 ohms. It has 2 - 8 ohm speakers. Can someone tell me how to I wire it to 16 ohms (so I can run it parallel with another 4 ohm cabinet & make rig run at 8 ohms)?
You can run the two cabinets in series to get an eight ohm load.

To do that, I think it is better to make a little box with the connectors wired in series. That way you can use standard speaker cables for all connections. Otherwise you have to be sure to label your custom cables and be certain that you don't use them in unintended ways.

The wiring diagram posted previously shows how to do it. Instead of the speaker terminals you would wire to jacks in exactly the same way.

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