Same cab, same speaker type - different Ohms in each cab

[BrianC]

So you have two cabs both loaded with two speakers of the same pair in each, one is and 8 ohm cab and the other is a 16 ohm cab.

Will they sound the same running at the proper amp setting?

PS: one might be wired in parallel and the other in series.

 

[elvis]

The 16 Ohms cab will be two 8s in series. The 8 Ohms will be two 16s in parallel. They will sound a little different. I prefer the 16 Ohms speakers myself.

 

[Deleted member 5962]

The 16 Ohms cab will be two 8s in series. The 8 Ohms will be two 16s in parallel. They will sound a little different. I prefer the 16 Ohms speakers myself.

I've only had singles of same kind of speaker, different ohms, but I did put them in identical cabs. This is tricky business, IMO... I preferred one with some amps/pedals/tones, and the other one with other amps/pedals/tones. What really got tricky, is that other factors start to introduce themselves, because I had one I preferred with one amp at moderate volumes, but when I turned it up loud, preferred the other one... but then you're throwing in cab size and resonances, room placement and contributions, etc., etc., IMHO. I had them right next to each other and both about a foot from the back wall, in the middle of the room wall (away from corners), so as even as possible. But I say that because I also took those two cabs to one of our guitar "get together weekends" and in a big open stage, lots of room, and the speaker well out into the room (20 feet from the back wall) my preferences changed from what I previously decided...

 

[GuitarJammin]

Then get two 8 ohm speakers in a 2x12 cab and experiment with 4 ohm as well. Don't have the same type of speakers in different ohm types, I think, in a rather un-scientific way mind you, that they feel different too swapping between 4, 8, and 16 ohm in the way the amp reacts to the player. Tone wise i can't say much, because i don't have the same speaker type in two different impedances.

My main motivator in cab selection is usually tone goals for what I'm about to do...I like all my cabs...but I need more amp heads now.

 

[RickP]

There is a very involved relationship between the speaker load, transformers, and the tube. When one variable changes, the parameters of all are affected. When you change speaker impedance, you change voltages elsewhere, including the tubes. Like moving the bias, that’ll affect a lot about how an amp feels or sounds. It can also effect how the amp smells, if you get outside the limits of the components!

I don’t pretend to be an expert, and have to go read up on it every time I start down this path.

 

[BrianC]

I tried the cab in question which is two 8 ohm speakers in series (16 ohms) with the amp running at 16 and at 8.

There was a VERY small tonal difference. Not enough not to just run it matched.

 

[shinksma]

So you have two cabs both loaded with two speakers of the same pair in each, one is and 8 ohm cab and the other is a 16 ohm cab.

Will they sound the same running at the proper amp setting?

PS: one might be wired in parallel and the other in series.

Will they sound the same? "Probably not."

Running the amp at 8 ohms means you are not using the full capability of the output transformer, which is obviously also capable of 16 ohms. The amp will react ever so slightly differently, probably.

Even if not that, as noted you have differently rated speakers in each cabinet. A 16 ohm speaker has more voice coil windings and probably bigger magnet, and that may impact the build of the housing etc. I would also wager that an 8 ohm version of a speaker model has a slightly different impedance graph vs the 16 ohm version. Not miles difference, but a difference.

And on top of that, you have two speakers in parallel vs in series. Speakers are never perfectly matched, just very very very close (usually), there's got to be some almost imperceptible difference in their physical build (tiny variations in voice coil wire thickness, different magnetic field form the rare earth materials), so the parallel set-up will cause one speaker to react a bit differently than the other because their impedances will play differently - you'll get ever so slightly different current flows through each speaker. The series setup causes each speaker to see the same current flow as the other (only one "pipe"), but the other speaker is "in the way" of the voltage, so they see only half the voltage - but again, not perfectly, because they are not truly identical.

For everyday purposes, I bet you could hear the difference if you really wanted to pay attention.

But I would also say: just rock that amp & speaker cab!

 

[wilburtmcgroarty49]

I don't understand this at all, but I've heard that if you connect speakers in series, they can cause a short circuit. However, please don't listen to me since I'm far from electronics judging by what happened recently. My speakers started buzzing, and I decided to fix it, but in the end, my speakers just burned out. Therefore, I have already decided to buy new ones and never fix anything on my own again. By the way, I chose between edifier r1700bt vs r1280db, and I think I will order the second option.

 

[RickP]

I do not understand this at all, but I have heard that if you connect the speakers in series, they can cause a short circuit

It’s a common configuration, though less common in two-speaker guitar cabs than parallel. Older Vox AC30s combos are series wired, for instance, though I don’t know how the newer Chinese ones are connected. Many 4x12 cabs (Marshall, for one) use a combination: series/parallel wiring. Properly connected, series wiring is as safe as any other method, and offers an option for creating certain resistance values with a given number of speakers. Whether or not that loading is safe for the amp in question is another matter.