4x10 cab questions?

[Ausbass1970]

Gday from West Australia.
This is my first post on something that has had me intrigued for a while now.

1) I'm using an old SS600 min 4 ohm load Labsystem Head with two speaker outputs and Labsystem 410h 450w @ 8ohms cab.
Ibanez sr405qm.

Playing in 2 bands. Playing everything from Adelle to Bon Scott. Doors, Pink Floyd, U2, Amy Winehouse, Robert Cray....

I totally love the sound. Its the first rig I've owned that I didn't have to fight with to get the sounds I'm after.

Now, lean back, here comes the drill:
I get the feeling that people often ask the wrong question when they ask "can I rewire my 8ohm cab into a 4ohm load?"
Knowing the answer to this question made me look in other directions. So here it is;

Would it be possible to rewire the cab into 2 separate banks of 2x10's, retaining the 8ohms of each bank but having a separate input jack for each bank of 2x10's.
Thus drawing out 2 8ohm loads into the one cab creating 1x4ohm load?

I was considering a switch so I could switch it from 4x10 to 2x2x10..

Also, what to do with the single tweeter?

What are the pros and cons of doing something like this?
Or is this just a case of temporary insanity from insomnia?

Anyways.
Looking forward to your thoughts.
Cheers
Andrew.

 

[Mushroo]

It is possible to rewire your 8 ohm 410 cab to 2 ohms, 8 ohms, or 32 ohms total. There is no 4-speaker wiring solution that can possibly give you 4 or 16 ohms total.

You said your head is "minimum 4 ohms"? Double-check the manual, but this probably means it is perfectly safe to use with an 8-ohm cabinet, and you have absolutely nothing to worry about.

(edit) @voided3 has a more accurate answer, if your drivers happen to be 32 ohms.

 

[voided3]

If your 4x10 cabinet is 8 ohms, each individual speaker most likely is either 8 ohms (wired as a set of four in series-parallel) or 32 ohms each (all wired in parallel, as often seen in Ampeg cabinets).

If each individual speaker is 8 ohms, your two most logical wiring options are series-parallel for a total 8 ohm load (as it is now, most likely) or all in parallel for a 2 ohm load, which your amp does not support. If you break out the speakers into pairs, each pair can either be:

• Wired in series, 16 ohms per side. Combining each side in parallel would result in an 8 ohm load.
• Wired in parallel, 4 ohms per side. Combining each side in series would result in an 8 ohm load, and combining each side in parallel would result in a 2 ohm load (which your amp doesn't support).

If each individual speaker is 32 ohms, your only logical option is to leave it as-is in parallel for a total 8 ohm impedance. As above, you could break it out into a 16 ohm stereo pair, but it wouldn't provide a benefit.

The TL;DR version: No, if your 4x10 is 8 ohms, you cannot rewire it to be 8 ohms per side stereo for a total 4 ohm load.

You can replace your speakers with either 16 ohm or 4 ohm drivers to get a final 4 ohm impedance, but that opens a whole other can of worms about driver compatibility with your existing cabinet.

Also, and I presume this is the goal, you won't get an appreciable increase in headroom going from an 8 ohm 4x10 to a 4 ohm 4x10. Adding a second identical 4x10 will probably blow down your house, though.

 

[Old Garage-Bander]

In general cabs are designed and tuned to work with the intended drivers.
To do what you propose may entail physically separating the space, inside the cab, between the two pairs of speakers.
You would need to consider if four speakers in a common space is equal to two pairs of speakers in half the space.

From what I can tell, your amp is a single (mono) amp with two output jacks.
That being the case, one speaker cable from one of the jacks to all 4 speakers is no different than two cables from each jack to two pairs of speakers. You gain nothing and may well have ruined your cab, or at least affected how it sounds.

 

[Ausbass1970]

If your 4x10 cabinet is 8 ohms, each individual speaker most likely is either 8 ohms (wired as a set of four in series-parallel) or 32 ohms each (all wired in parallel, as often seen in Ampeg cabinets).

If each individual speaker is 8 ohms, your two most logical wiring options are series-parallel for a total 8 ohm load (as it is now, most likely) or all in parallel for a 2 ohm load, which your amp does not support. If you break out the speakers into pairs, each pair can either be:

• Wired in series, 16 ohms per side. Combining each side in parallel would result in an 8 ohm load.
• Wired in parallel, 4 ohms per side. Combining each side in series would result in an 8 ohm load, and combining each side in parallel would result in a 2 ohm load (which your amp doesn't support).

If each individual speaker is 32 ohms, your only logical option is to leave it as-is in parallel for a total 8 ohm impedance. As above, you could break it out into a 16 ohm stereo pair, but it wouldn't provide a benefit.

The TL;DR version: No, if your 4x10 is 8 ohms, you cannot rewire it to be 8 ohms per side stereo for a total 4 ohm load.

You can replace your speakers with either 16 ohm or 4 ohm drivers to get a final 4 ohm impedance, but that opens a whole other can of worms about driver compatibility with your existing cabinet.

Also, and I presume this is the goal, you won't get an appreciable increase in headroom going from an 8 ohm 4x10 to a 4 ohm 4x10. Adding a second identical 4x10 will probably blow down your house, though.

Thank you.

If your 4x10 cabinet is 8 ohms, each individual speaker most likely is either 8 ohms (wired as a set of four in series-parallel) or 32 ohms each (all wired in parallel, as often seen in Ampeg cabinets).

If each individual speaker is 8 ohms, your two most logical wiring options are series-parallel for a total 8 ohm load (as it is now, most likely) or all in parallel for a 2 ohm load, which your amp does not support. If you break out the speakers into pairs, each pair can either be:

• Wired in series, 16 ohms per side. Combining each side in parallel would result in an 8 ohm load.
• Wired in parallel, 4 ohms per side. Combining each side in series would result in an 8 ohm load, and combining each side in parallel would result in a 2 ohm load (which your amp doesn't support).

If each individual speaker is 32 ohms, your only logical option is to leave it as-is in parallel for a total 8 ohm impedance. As above, you could break it out into a 16 ohm stereo pair, but it wouldn't provide a benefit.

The TL;DR version: No, if your 4x10 is 8 ohms, you cannot rewire it to be 8 ohms per side stereo for a total 4 ohm load.

You can replace your speakers with either 16 ohm or 4 ohm drivers to get a final 4 ohm impedance, but that opens a whole other can of worms about driver compatibility with your existing cabinet.

Also, and I presume this is the goal, you won't get an appreciable increase in headroom going from an 8 ohm 4x10 to a 4 ohm 4x10. Adding a second identical 4x10 will probably blow down your house, though.

Thank you. Voided3.
All speakers are 8 ohms and each bank would have its own direct line from the back of the amp.
Yes the SS600 is a min 4ohm load.

Much appreciate your time and input.

 

[Ausbass1970]

In general cabs are designed and tuned to work with the intended drivers.
To do what you propose may entail physically separating the space, inside the cab, between the two pairs of speakers.
You would need to consider if four speakers in a common space is equal to two pairs of speakers in half the space.

From what I can tell, your amp is a single (mono) amp with two output jacks.
That being the case, one speaker cable from one of the jacks to all 4 speakers is no different than two cables from each jack to two pairs of speakers. You gain nothing and may well have ruined your cab, or at least affected how it sounds.

That's exactly what I wanted to hear.
Thank you so much for clearing that up.

 

[Mushroo]

All speakers are 8 ohms and each bank would have its own direct line from the back of the amp.
Yes the SS600 is a min 4ohm load.

Can your amp handle a 16 ohm load?

If the answer is yes, then here's what you can do:

Wire each bank of 2x10 in series. This will give 16 ohm for each pair. If you connect 1 bank to your amp, then it sees a 16 ohm load. If you connect 2 banks in parallel, then your amp sees a 8 ohm load.

You don't want to wire each bank of 2x10 in parallel. That would result in 4 ohms per bank, or a combined 2 ohms for 2x2x10, which could damage your amp.

There's absolutely no reason to do this project (it won't improve the sound of your cab, or make it louder) but it is an interesting intellectual exercise.

 

[voided3]

All speakers are 8 ohms and each bank would have its own direct line from the back of the amp.
Yes the SS600 is a min 4ohm load.

In that case, I would not modify the cabinet.

If modified, the cabinet would be either 4 or 16 ohms per side, resulting in a final 8 or 2 ohm load when both are hooked into the amp, unless you replace the speakers (which I don't recommend unless the drivers are blown).

I presume your amp is solid state. There's no harm in running it at 8 ohms, it will just put out a little less power. Adding speakers is the more efficient way to add usable volume, and you're already using a 4x10 so that's a good sized cabinet. If you need to go louder, a second 8 ohm 4x10 will A) double your speaker area and B) drop you down to the minimum 4 ohm load.