Transformer question...

[B2D]

Recently in an issue of Guitar World in the Tech Ed section, a reader wrote in asking what the tonal differences between 8 and 16-ohm speakers were.

Matt Bruck, the writer for the column, responded that if you compare two of the same speakers with different ohmages side-by-side, the 8-ohm model will have a greater midrange content than the 16-ohm model will. This is consistent with what I've learned from various people on here over the years...

THEN he said something that kinda surprised me. He said:

My preference is for a 16-ohm cabinet driven by an amp at its 16-ohm setting. This is because an amp's 16-ohm setting uses the output transformer's full winding; the 8-ohm setting uses only part of the output transformer. In other words, the 16-ohm setting gives you all the tone the amp is capable of producing.

My question is this - is it true that 16 ohm settings use the full transformer coil to do the work and 8-ohm settings only use half? If it is can someone explain to me how that works, electronically? I usually run an 8-ohm output into an 8-ohm cab, am I not getting "all the tone the amp is capable of" that way?

Any light shed on the subject is appreciated.

 

[STRATDELUXER97]

Re: Transformer question...

I always thought that each impedence selection was just a certain tap taken at a given point within the windings...I always thought also,that the 16 ohm setting would give more gain at the output because of "possible" coil saturation..

Not sure if I really even know what I'm talkin about either? LOL

 

[Artie]

Re: Transformer question...

John, you are correct. At least on the first part. When they wind a multi-tap transformer, its like winding a tapped pickup. They stop when they get to the 4 ohm amount, add a wire, then keep winding. When they get to the 8 ohm point, they add another wire, and then continue on to the 16 ohm point.

While technically, the 16 ohm point does use more output windings then the 4 or 8 ohm taps, I can't really say whether or not there's any advantage of one over the other. This starts to get into an area where I just don't have enough experience to say.

 

[Scott_F]

Re: Transformer question...

In my own personal experience, I've always found the difference to be pretty subtle. But, that's what we all live for, right?

In the case of my Tweed Pro, I had it as a Tweed Super 2x10, running 4 ohms total impedance. Then as a 1x15, I'm using an 8 ohm. Theoretically, I'm using "all" the windings at 8 ohms instead of 4. (only options were 4 and 8 on this OT). I firmly believe the amp sounds 10x better with the 8 ohm 1x15, but I'm betting it has more to do with the speaker than the OT impedance.

 

[STRATDELUXER97]

Re: Transformer question...

Marshall always set their amps up for the 16 ohm load and I always wondered why? Fender/Boogie liked 4 ohms when they used 2 speakers together...

 

[Jeff Seal]

Re: Transformer question...

This happens to be one of my favorite subjects.... the tone difference is actually quite substantial from 4/8/16.. (I personally run 16 ohms almost all the time, I even wired my 4 412's to 64 ohms..switchable back to 16...to run 16 G12T75's at 16 ohms...too bad I don't get to use it very often..)

<---this pic is one of the few times....although you can't see them, there are two more 412's right next to them.

The 16 ohm winding does allow the entire secondary side of the tranny to be used and it usually ends up being a "wider" spectrum than 8 or even 4 ohms.
Since the transformer doubles the amount of windings from 4 to 8 and then quadruples the windings from 4 to 16, the greater the number of windings, the less phase cancellation will occur within the tranny thus more lows, or conversely less lows and low mids when using the 8 or 4 ohm tap. (Thus creating the impression of more mids.)

This in no way implies one is better than the other, Eric Johnson wires all his 412's to 4 ohms and, needless to say, it works quite well for him . But it is definitely worth exploring....and since we happen to be here, same applies with pickups.... I'm happiest tone wise with my Marshall 800 running at 16 ohms through all 16 G12t75's, and my SD SH-6's.....heaven!!! (although rather "impratical"..)

Jeff Seal

 

[aleclee]

Re: Transformer question...

Everything affects everything. Just because something like number of transformer winds affects tone doesn't mean that "more=better".
Think about this one: the 16 ohm speaker has a different number of winds in its coil, too.

 

[Gearjoneser]

Re: Transformer question...

If you're comparing 1/2 power to full power, the full power always sounds better, probably for the reason stated.

I only know what my ears thinks is best, and that's a 100W 16ohm amp running into a 4-12 16 ohm amp. I've heard every other variation with tons of amps, and there's nothing that packs the toneful wallop of that combination. Of course, that combo isn't feasible for everyone's situation, but I still think it sends the most shivers up my spine.