Crosspost: Changing cab impedance

[nos]

I posted this in the DIY forum, but thought I'd pose the question here too.

 

The bass player in my band wants to try a different impedance rating in his bass cab. It is a single speaker rated at 8 ohms. The head (Traynor YBA200) he bought from me sounded really good through my 4 ohm cab but I sold it to someone else. It sounds pretty farty with his 8 ohm cab. He wants the 4 ohms without buying another cab.

 

So here's what I want to do: I want to simulate adding another speaker to the cab by putting 8 ohms of 200W wire-wrapped resistors in parallel with the existing speaker. This would drop the rating down to 4 ohms. I'd put it in an external box with heatsinks.

 

Do you think this would accomplish what we're looking for? Any idea how it would affect tone?

[misterhinkydink]

It will only make it quieter. What are the other differences in the two cabinets?

[AntiStuff]

I think it will work, but it'll be a lot of wasted power. Make sure it's heatsinked properly.

[guitargod0dmw]

If it's a single 8 ohm speaker, why not just replace it with a single 4 ohm speaker?

[Zeromus-X]

I don't see how this is going to make the change you think it's going to make. You'll be sending more power out of the amp, then splitting it to two outputs, thusly halving the power it's getting. At best you're going to be sending the speaker LESS power than you started with, thus driving the amp harder, thus making it sound even more... "farty".

[nos]

 

It will only make it quieter. What are the other differences in the two cabinets?

 

 

I don't have his cab in front of me, so I'm not too sure about it. It's a Trace-Elliot and I'm pretty sure its a single 15. My cab was an Ampeg 412HE.

 

I'm thinking the 4ohm speaker might be the way to go.

[Jazz Ad]

The Traynor YBA200 is a tube amp.

It puts out exactly the same power at 4 or 8 ohms.

Your friend's problem is elsewhere.

[J.]

Jazz Ad is right. The impedance has nothing to do with it. If your bass player is unhappy with his cab, then he needs to get a different one. The ohm rating on a speaker cabinet does not determine how it sounds - in fact it doesn't have anything to do with it at all. Granted, an amp will put out a little more power into a 4 ohm cab than an 8 ohm cab (all else being equal), but the difference is usually negligible.

 

The reason the amp sounds different through the two cabs is because the cabs themselves were very different. A Trace Elliot 1x15 is a very different beast than an Ampeg 412HE.

 

I wouldn't waste your time trying to mod the guy's cab. It's best to look for a different one if he's unhappy with the performance.

[Crescent Seven]

 

Granted, an amp will put out a little more power into a 4 ohm cab than an 8 ohm cab (all else being equal), but the difference is usually negligible.

 

 

The volume difference between an 8ohm and 4ohm configuration in the same cab is going to be nil. If your bassist wants more volume, he needs to add another 8ohm cabinet. If I remember the formula right, you basically need to deliver 10x the power to give you 2x the volume, and the power increase by going from 8 to 4ohms is less than double. However, more drivers will give you more sonic output at the same power.

 

Dicking around with resistors and such is a good way to potentially mess up the amp, with no real benefit.

C7

[guitargod0dmw]

The Traynor YBA200 is a tube amp. It puts out exactly the same power at 4 or 8 ohms. Your friend's problem is elsewhere.

 

Damn! I always forget that! Maybe this time it will stick...

And to think...I own a {censored}ing tube amp.

[nos]

Thanks for the help, y'all. He was trying not to have to buy another cab because he likes the one he has when he uses his Trace V4. Plus its small and pretty light. Unfortunately, it (the V4) overheats sometimes and shuts down. The Traynor is his backup.

 

So... anyone have any good suggestions? Price is very important, but even more so is availability. He needs something GC would carry or could order. He's not one to buy sight-unseen.

 

I'm a bass player too, so I do speak bass. But I don't shop around, so what do you say?