#1
Before you say anything, yes I did read the stickies I just didn't understand them. I already have a head at the moment it's an Ashdown MAG and I'm now looking for a cabinet. I'm not sure of how to match impedance. I know from the stickies that you want a cab that has higher or equal to wattage than the head, but I'm not sure about ohms. I'm also not sure what the impedance is of that head I think it's 8ohms but I'm not sure. What is the impedance that would match an 8ohm head? Would a 4ohm cab match an 8ohm head? Or a 4ohm cab match an 8ohm head? And what would you suggest for cabs? I've been looking at Carvin but I'm not sure yet because I don't know how to match them. Keep in mind I only want 1 cab.
Last.fm

Fender Deluxe Players Strat > Big Muff > LPB-1 > Moog Ring Mod > MXR Dynacomp > MXR Phase 90 '74 > Fender Hot Rod 410 (soon)
#2
Most of the time you can't get one cab to go with a head, most of the time you need to buy two Cabs to get the most out of your head
All I want is for everyone to go to hell...
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Quote by DisarmGoliath
You can be the deputy llamma of the recordings forum!
#3
The head doesn't have an impedance, what it has is a minimum the impedance of the cab you use can be. If a head says its minimum impedance is 2 ohms then that means you want a 2, 4 or 8 ohm cab.

Your MAG will be perfectly happy with a 4 or 8 ohm cab.
#4
Heads don't have ohmages. They merely pump different wattage at different ohmage and have a minimum ohmage that they can maintain and not catch fire or some othwer terrible thing. That head can use any ohmage over 4 ohms. So any cab combination that results in 4 ohms or less is fine.
#5
It is advisable to get a cab with an impedence that allows you to build on the rig for example if the amp will run into a minimum of 4ohms then you should start with an 8 ohm cab so that later on you can add another 8ohm cab which will give you the 4ohm impedence where your amp produces it maximum ouput.
Start with a single 15" 8 ohm cab and add a a 2x10+horn cab later.
G&L L2500
Squier Affinity Jazz Bass 5
Ashdown RPM pre-amp
Ashdown Little Giant 1000
300 watt 15" powered cab
450 watt 15" powered sub bass cab
2x10 + horn
1x15x10 + horn
#6
Actually, amps have an output impedance: 2,4,8 ohm. There is a big ol' transformer sitting out on the amp output. When you match the speaker impedance to the output impedance of the amp, you will be delivering maximum power to the speaker. If you go less than the impedance of the amp it will draw too much current through the transformer; if you go more than the impedance then there isn't enough current to rattle the neighbor's windows.

Take these guy's advice: they know their amps/cabs/bass stuff. if you buy a 8 ohm cab, you can always buy another and parallel it to bring it down to 4 ohms
#7
Quote by terb
Actually, amps have an output impedance: 2,4,8 ohm.

The impedence range is usualy 4 to 16 ohms, some amps claim to work down to 2 ohms; my feelings are that for bass this is not always prudent.
G&L L2500
Squier Affinity Jazz Bass 5
Ashdown RPM pre-amp
Ashdown Little Giant 1000
300 watt 15" powered cab
450 watt 15" powered sub bass cab
2x10 + horn
1x15x10 + horn
#8
Quote by John Swift
The impedence range is usualy 4 to 16 ohms, some amps claim to work down to 2 ohms; my feelings are that for bass this is not always prudent.

What do you think about mono-bridging in stereo amps? From what I understand, there's the equivalent of running power amps in series, i.e. both power amps running at 2 ohms each, giving the combined wattage value of both power amps at 2 ohms, but together operating as 4 ohms?
Quote by Cody_Grey102
I was looking at a used Warwick Vampyre LTD 5'er for about $200. I went home to grab my wallet and came back and some jerk with an epic beard got it already..
#9
Thanks for the help guys. I hate to turn this into a gear thread, but what would you suggest I look at?
Last.fm

Fender Deluxe Players Strat > Big Muff > LPB-1 > Moog Ring Mod > MXR Dynacomp > MXR Phase 90 '74 > Fender Hot Rod 410 (soon)
#10
I don't know much about power amp circuitry (just learning about it now) if you parallel the output transformer with another transformer it will drop the impedance to half... so im not sure how a power amp like thefitz mentioned works. Maybe by putting them in series it allows for the extra current draw?.
#11
most amps i've seen (this would be in the power amp only category) that only go down to 4 ohms per side only let you bridge at 8+ ohms per side.
i thought i had magic fingers once, and had uncovered the fountain of love.

turns out my girlfriend was just peeing on me.
#12
Well, most modern stereo amps have a 4-ohm mono bridge and 2 ohm per side operations. SWR SM-500 to 1500, Ampeg SVT4PRO, Carvin BX600-1200, a few Edens I believe...
Quote by Cody_Grey102
I was looking at a used Warwick Vampyre LTD 5'er for about $200. I went home to grab my wallet and came back and some jerk with an epic beard got it already..
#13
Quote by thefitz
What do you think about mono-bridging in stereo amps? From what I understand, there's the equivalent of running power amps in series, i.e. both power amps running at 2 ohms each, giving the combined wattage value of both power amps at 2 ohms, but together operating as 4 ohms?
That's how I ran my old Studiomaster 1200D power amp, in stereo it was 600 watts per side each into 4 ohms or 1200 watts bridged into 8 ohms.
G&L L2500
Squier Affinity Jazz Bass 5
Ashdown RPM pre-amp
Ashdown Little Giant 1000
300 watt 15" powered cab
450 watt 15" powered sub bass cab
2x10 + horn
1x15x10 + horn
#14
Quote by John Swift
That's how I ran my old Studiomaster 1200D power amp, in stereo it was 600 watts per side each into 4 ohms or 1200 watts bridged into 8 ohms.

Wow, that's a lot of power into an 8-ohm cab.

But what do you think of the fact that the modern ones are running at 2 ohms each, 4 ohms total instead of 4 ohms each, 8 ohms total? Is it not safe?
Quote by Cody_Grey102
I was looking at a used Warwick Vampyre LTD 5'er for about $200. I went home to grab my wallet and came back and some jerk with an epic beard got it already..
#15
Quote by thefitz
Wow, that's a lot of power into an 8-ohm cab.

But what do you think of the fact that the modern ones are running at 2 ohms each, 4 ohms total instead of 4 ohms each, 8 ohms total? Is it not safe?


It would seem that todays power amps are up to it although on this side of the pond you don't see too many 4 ohm cabs that would get you down to 2 ohms.

At one time I had a 2x10+horn peavey that was 4 ohms so I wired the speakers in series to make it 16 0hms with my 8 ohm 15" taking the bulk of the work that gave me around 5.3 ohms.
G&L L2500
Squier Affinity Jazz Bass 5
Ashdown RPM pre-amp
Ashdown Little Giant 1000
300 watt 15" powered cab
450 watt 15" powered sub bass cab
2x10 + horn
1x15x10 + horn