Some suggstions on the speakers?

[darkbluemurder]

Ideally you want 16ohm total to get the optimal sound from your amp.

Is that true or is it a myth?

Other problem with 16 ohms total in a 2x12 is you have to go with series wiring which is a bit less safe (for your amp) if one of the speakers blows or if something fails in the cab, since the amp won't see a load. (I'm not saying anything you don't know, I know you build amps and know way more about amps than I do, I'm just saying this for Thomas's benefit.)

It is a myth. If your amp has an output transformer with taps for different loads they are purely there for convenience.

And the other point you mentioned is very valid. If one speaker of a series fails, the cab will be silent. If one speaker of a parallel wired cab fails, the other will continue to function - unless is overpowered by the fact that it now has to handle the entire power from the amp.

Cheers Stephan

[dave_mc]

^ 

(a) I like 16ohm cabs.
I use 16 ohm because I think a lot of output transformer winding patterns tap the 16ohm wind to get the 8ohm and 4ohm tap. 16ohm uses the whole secondary. I'm not sure how true that is of ALL OT's. though. IT'll vary according to winding pattern.

(b) The other thing to consider I believe, is the "push" of the speaker which is related to its construction and various trade offs like wire gauge on the voice coil for a given speaker. The "push" calculation is something I was reading about recently that was put online by a celestion tech I think... although I can't find it now. But 8ohm speakers have more "push" and thats partly why they sound different to 16ohm versions of the same speaker. Although there are enough differences due to manufacturing that can also have an impact. If I can find the thread I'll post it up. It was interesting.

(c) The point about the series wired 8ohm speakers is good though. It's true that if you have series wired speakers and one fails your head will see a zero load and that is a bad thing.

(a) Yeah, I know that (in theory) if you use 16 you're using "all" of the OT's windings, but does that actually translate to any benefit in the real world? I know I was satisfied (with my limited trying) than any differences were small enough that they weren't worth worrying about- and I was changing the type of wiring too (series to parallel) which should also affect the tone slightly.

Not saying it necessarily doesn't make a difference, just I hear so many of these myths about guitar tone that I pretty much start out from a point of scepticism these days

(b) I wasn't aware of that, that's interesting. I know every so often you hear people who've been able to try both say that the different impedance versions of the same speaker can sound slightly different... but then as you said, manufacturing tolerances can also lead to differences.

(c) Yeah. I mean, it's not ideal if a speaker fails, since the load is at the wrong impedance... but it's a lot better than no load.

I suppose though that at least if you get no sound (as in series) it's pretty obvious, and you know to fix it. If you weren't totally on the ball a speaker could possibly fail when wired in parallel and you might not notice it.

[Dmoney]

yeah, I think with all these things it's minor differences.

I've been trying to find more about the impedance affecting tone. I can't find the original thing I read. It was something like two similar speakers, say an 8ohm V30 and a 16ohm V30, will potentially sound different due to manufacturing tolerance, but also because the voice coils have different gauge wire, and a different amount of turns on the voice coil, making one voice coil heavier than the other. The 8ohm voice coil I think uses less turns of heavier wire, and the 16ohm uses more turns of lighter wire. A 4 ohm speaker often uses to the same wire as a 16ohm, but its cut into two length that are wired in parallel. So the weight of the coil, and the inductance differences due to voice coil winding (and probably some other stuff) can potentially have an effect. But still, it's not going to be night and day. Just slight differences in sensitivity and response I guess.

[dave_mc]

^ Thanks. Yeah like a lot of these things there's sometimes a difference between theory and practice- I'm not saying in theory there might not be a difference, just (as I said, based on my very limited trying) in practice the difference seems to be subtle at most. And that's before you consider how prone the guitar world is to myths!

Of course, it's also possible that the difference might be more noticeable with different speaker models- maybe the ones I tried minimised the differences (I was also using two mixed speakers in the 2x12, so maybe that affected it, too).

[Toe-Knee]

I've actually found it to be a really drastic difference going from 4ohm yo 16ohm. It's a lot brighter and the lows and as murky in general. More punch as such.

It's significantly more noticable with my MKIIC+ when ran at 16ohm it's a little too bright and edgy so 8 is a good middle ground on that. However the original IIC+ only had 4/8ohm taps

[dave_mc]

That's interesting. Maybe different amps and speakers do affect how much difference it makes.