modding ampeg cab's Ω switch

[fithers]

heya fellas!

i just got a sunn coliseum 300 and am hunting for cabs. i'm looking for a 4Ω 215, 410, or even a 610 if i can find one.

i really like the ampeg cabs for their sound and build/tilt-back and yesterday i checked out a b25 and a v4b. They both had a switch on the back that lets you alternate between 4Ω and 16Ω but i'm wondering if it would be possible to mod this to toggle between 2Ω and 4Ω?

im pretty new to all of this.

the coliseum 300 is rated at 120W at 8Ω, 200W at 4Ω, and 300W at 2Ω. I want to have the option to blast 300W without having to lug a 2nd cab around. This Ω switch mod would be most crucial.

whadda you think?

[coreyfyfe]

2 and 4 wouldn't be possible. The 4 and 16 toggle switches between series and parallel wiring with two 8 ohm speakers. If you put in 4 ohm speakers you could do 2 and 8 ohms, but there isn't a way to wire that kind of setup to 2 and 4 with good results.

[fithers]

thanks man, 2 and 8 might actually be better. would i be able to do it myself or is it a job for a tech?

[coreyfyfe]

If you have one of those cabs already, all you'd have to do is swap in some 4 ohm speakers for the 8 ohm speakers and you're good to go. Finding the right speakers that will sound good with that cab isn't necessarily as easy as it may sound though.

If you're talking about adding a switch to a 2x15 cab without one, unless you know how to do the wiring, I'd let someone with experience do it. It's not a hard thing to do, but IMO I like to know things are done right.

[panama]

Do this right and get 2 4ohm 810s.

[KramerBassFan]

You Canno' change the laws of physics.

[fithers]

i don't have one yet but there is a b25b cab for $300 i might grab, then it would just be a matter of swapping out the speakers for a pair rated at 8Ω?

[fithers]

lol

[fithers]

any ~$100 speakers you would recommend?

i would love to have an enormous rig but i live in a tiny apt in nyc and don't have a car.

[BassmanPaul]

Originally Posted by fithers

i don't have one yet but there is a b25b cab for $300 i might grab, then it would just be a matter of swapping out the speakers for a pair rated at 8Ω?

As Corey intimated in his post, it's not that simple. The drivers have to match the enclosure to work at their best. You will have to measure the box and its ports, if any, and plug the values into a box design program like WinISD. Please read the FAQ on page one for more on this.

[coreyfyfe]

Originally Posted by fithers

i don't have one yet but there is a b25b cab for $300 i might grab, then it would just be a matter of swapping out the speakers for a pair rated at 8Ω?

The B25 cab came with 8 ohm speakers (hence the 4/16 switch). You'd want to find 4 ohm 15s that fit the specs of the cab. As Paul said, if you want it to sound good, you'll want to go through the specs of the cab and speakers to get it right. For under $100 each? Probably wont find much. You'd be better off just using the cab at 4 ohms, or better yet, getting a different cab that is 4 ohms and has more speaker area (like an 8x10).

[krovx]

I would just invest in buying the right cab...find a 4 ohm cab. You will pay more but it sure beats messing around, having it not work out, selling all the parts at a lost to only end up buying a 4 ohm cab. Save yourself the time, money, and headache.

[fithers]

right on thanks guys. i'm asking because i would really like to be able to get all 300watts out of my head with one 2Ω cab. i think the speaker swap sounds pretty reasonable and there are a couple on ebay i could spring for.

any winners?
15 4ohm bass speaker items - Get great deals on Musical Instruments, Computers Networking items on eBay.com!

[fithers]

the biggest argument against my plan here is that i have no idea what i'm doing

[RickenBoogie]

and, "getting maximum wattage" from your amp is not nearly as important as having good, plentiful speakers, re: both tone ,AND volume. Just because the amp puts out max wattage at 2 ohms, does not necessarily mean a single 2 ohm cab is the best solution. Best bet, a pair of good 4 ohm cabs, preferably with many speakers each, ie: an 810.

[coreyfyfe]

Originally Posted by fithers

the biggest argument against my plan here is that i have no idea what i'm doing

That's probably the most disconcerting thing about the whole experiment. Getting an extra 100 watts out of that head will give you a modest volume boost. Having more speakers will give you just as much, if not more of a volume boost.

[coreyfyfe]

Originally Posted by KramerBassFan

You Canno' change the laws of physics.

You can try, but only if you have a good marketing department *cough*accuswitch*cough**cough*

[Bass_Pounder]

Originally Posted by fithers

right on thanks guys. i'm asking because i would really like to be able to get all 300watts out of my head with one 2Ω cab. i think the speaker swap sounds pretty reasonable and there are a couple on ebay i could spring for.

Originally Posted by fithers

the biggest argument against my plan here is that i have no idea what i'm doing

No offense, but it is abundantly clear............

Especially because you are making a big issue out of getting 300 watts Vs 200 watts from your head.

Increasing from 200 to 300 watts (with all else being equal) will only give you around 1.5 to 2db increase, which is not even audible.

[panama]

Dude. 2 810s is going to sound worlds better than pumping 300 watts through a 2ohm 215.

And don't buy random good deal speakers off of ebay. Sheesh.

[dincz]

Originally Posted by Bass_Pounder

Increasing from 200 to 300 watts (with all else being equal) will only give you around 1.5 to 2db increase, which is not even audible.

It will be audible (1dB change is just audible) but definitely not significantly. More speakers needed.