16 ohms versus 8 versus 4

[korovamilkdud]

So maybe you have a halfstack. You know to match your impedences properly, like a good lad.

But is there a specific change happening within the amp's and cab's guts when switching back and forth between the two? In other words, 8ohm amp output to 8 ohm cab, 16 ohm output to 16 ohm cab, etc..:scratchch

 

[Kane17]

Re: 16 ohms versus 8 versus 4

hmm...a bit tired in thinking right now..but My GUESS is that for most amps its just receiving the output power from a different tap off of the transformer. I'm not sure if the AMP will feel the difference, however since many people get improved sound from swapping transformers I'd guess the change would be along the same lines in terms of speaker output. Probably minutely if noticeable.

As far as a cab switching, I've seen switches that change from series to parallel wiring (ie Power going through each speaker one after another vs power going through 2 sets of speakers on a half-stack simultaneously). The change is in the wiring but not the speakers themselves. The options can be limited on these because of the math..most practical ones are switchable 4 and 16 ohms.

PS, also I'm not quite sure if thats what you were asking about. Am I talking about what you are talking about?

 

[jones]

Re: 16 ohms versus 8 versus 4

hmm...a bit tired in thinking right now..but My GUESS is that for most amps its just receiving the output power from a different tap off of the transformer. I'm not sure if the AMP will feel the difference, however since many people get improved sound from swapping transformers I'd guess the change would be along the same lines in terms of speaker output. Probably minutely if noticeable.

PS, also I'm not quite sure if thats what you were asking about. Am I talking about what you are talking about?

You are right on the different tap bit.

Also, the lower the number the less the resistance, the more efficiently the amp will run. IE, put out more power and volume. Off course, if you are not running very efficient speakers, you may not notice.

 

[Kane17]

Re: 16 ohms versus 8 versus 4

Also, the lower the number the less the resistance, the more efficiently the amp will run. IE, put out more power and volume. Off course, if you are not running very efficient speakers, you may not notice.

Ah, that makes sense. Good to know. Thanks

 

[Funkfingers]

Re: 16 ohms versus 8 versus 4

Fiddling with the loudspeaker impedance selector affects the loading on the power stage valves (tubes). Underloading the power amplifier stage is a good way of destroying it and/or your output transformer.

 

[korovamilkdud]

Re: 16 ohms versus 8 versus 4

PS, also I'm not quite sure if thats what you were asking about. Am I talking about what you are talking about?

That's about right. The phrase, "how the amp feels" was the vibe.

 

[guitfiddle]

Re: 16 ohms versus 8 versus 4

as long as the ohmage matches the load, you'll get max rated power...there's no real advantge to any of them, but for how you want to run the speakers.

 

[CTN]

Re: 16 ohms versus 8 versus 4

I am not a good lad, i mismatch the impedances from amp to cab in a not so harmful way.

i go 8 ohms on the amp to 16 ohms on the cab.

My amp is only capable of 4 or 8 ohms. Cab's only capable of 4 or 16. I tried it with 4 ohms on each side, but it honestly sounds a lot better at 8/16 ohms

i'm gonna see if i can rewire my cab for 8 ohms cuz then it'd sound mucho better methinks, and there'd be less chance of it blowing up one day

 

[guitfiddle]

Re: 16 ohms versus 8 versus 4

I am not a good lad, i mismatch the impedances from amp to cab in a not so harmful way.

i go 8 ohms on the amp to 16 ohms on the cab.

My amp is only capable of 4 or 8 ohms. Cab's only capable of 4 or 16. I tried it with 4 ohms on each side, but it honestly sounds a lot better at 8/16 ohms

i'm gonna see if i can rewire my cab for 8 ohms cuz then it'd sound mucho better methinks, and there'd be less chance of it blowing up one day

Most tube amps will take a 100% difference in ohmage either way if the transformer is decent...I used to run my Music Man from the 4 ohm tap into an 8 ohm cab, but it sounds better if I match them.

 

[CTN]

Re: 16 ohms versus 8 versus 4

yeah I think i'm gonna have to get some 8ohm speakers, cuz the G12T-75s i have in there right now are all 16 ohms.

 

[eschoendorff]

Re: 16 ohms versus 8 versus 4

What about the utilization of the transformer windings? I was running a Marshall DSL into a Marshall 1960 cab - both set to the 4 ohm setting, thinking that I would get more power and tone at the least resistance.

Then one day I tried both head and cab on the 16 ohm setting and it made a wrold of difference in the sound. Someone had said taht it was because at the 16 ohm tap, I was using all of the transformer windings. Any truth to that? Can anyone explain how this could make everything sound better? I basically upped the resistance and now the amp sounds better? It just seems counter-intuitive...

 

[CTN]

Re: 16 ohms versus 8 versus 4

I think it has something to do with the frequency response that comes outta using all the transformer windings. might have more resistance, but the frequency response is more sonically pleasing...or something.. *shrug*

 

[korovamilkdud]

Re: 16 ohms versus 8 versus 4

:scratchch

 

[jones]

Re: 16 ohms versus 8 versus 4

What about the utilization of the transformer windings? I was running a Marshall DSL into a Marshall 1960 cab - both set to the 4 ohm setting, thinking that I would get more power and tone at the least resistance.

Then one day I tried both head and cab on the 16 ohm setting and it made a wrold of difference in the sound. Someone had said taht it was because at the 16 ohm tap, I was using all of the transformer windings. Any truth to that? Can anyone explain how this could make everything sound better? I basically upped the resistance and now the amp sounds better? It just seems counter-intuitive...

Yes I have heard that before, especially with Marshalls. Although some of my friends who run Egnator rigs swear they sound better off the 16 ohm tap as well.

 

[marvar]

Re: 16 ohms versus 8 versus 4

What about the utilization of the transformer windings? I was running a Marshall DSL into a Marshall 1960 cab - both set to the 4 ohm setting, thinking that I would get more power and tone at the least resistance.

Then one day I tried both head and cab on the 16 ohm setting and it made a wrold of difference in the sound. Someone had said taht it was because at the 16 ohm tap, I was using all of the transformer windings. Any truth to that? Can anyone explain how this could make everything sound better? I basically upped the resistance and now the amp sounds better? It just seems counter-intuitive...

Well, you wouldn't get any more power, at any given setting, as your amp is only capable of X? amount of watts, and a watt is a watt.
I have heard some discussion about using the full windings vs tapped or lower ohms, One camp says using the full windings utilizes more of the iron in the transformer,ie; more tone,or a different "feel"
the other camp says it's easier on your amp to run at lower ohms, ie: less heat
My thought is: The amp was designed to run into certain loads, set for what load you have, unless you are trying to create a certain tone. as mentioned in other posts.

 

[glassman]

Re: 16 ohms versus 8 versus 4

Actually, it depends on the transformer, or more specifically, how it was manufactured.

A standard output transformer with multiple taps will likely have very little difference in tone between the different taps as long as the tap matches the load.

An interleaved transformer with multiple taps will behave a little differently. Interleaving increases the capacitive coupling of the transformer, improving the coupling of higher frequencies. Unlike inductive coupling where only the utilized portion of the secondary couples with the primary, capacitive coupling utilizes the entire winding regardless of which tap is selected. This means using the 4 ohm tap will result in a brighter output since inductively, approximately ¼ of the secondary is being utilized and all of the secondary is capacitively coupled. On the 16 ohm setting the output will be flatter (frequency response) with full coupling in both regards.

Another consideration, regardless of construction, is that the 4 ohm tap is utilizing less windings than the 16 ohm tap. The bandwidth will remain the same. The 4 ohm tap, with its superimposed “air gap” may be slightly less efficient (most noticeable in an interleaved transformer) but it MAY have an improved transient response that would be to an equally small degree. This is entirely dependent on the quality of the laminations used, NOT the size.

The biggest problem with transformer design today is that they are being designed by EE’s that are trained in power transfer at a fixed frequency (power transformers) where it is entirely appropriate to throw more iron at a transformer to improve efficiency. The main issue with adding iron is that while it will increase bandwidth, it also increases eddy current losses and the hysteresis losses associated with lesser quality steel is still there. Higher quality steel will accomplish a full bandwidth coupling with less mass AND lower hysteresis losses. The whole notion these days that a bigger transformer is a better transformer is based on flawed engineering principles.

***edit*** There...I guess my 20+ years in the quality/applications engineering side of the magnet wire business wasn't a total waste after all!

 

[crguti]

Re: 16 ohms versus 8 versus 4

good transformer's knowledge Glassman. :notworthy

 

[jeremy]

Re: 16 ohms versus 8 versus 4

glassmans post is great. the other thing to take consideration of is that running your cab at different impedances changes the way the speakers are wired and that can change tone too.

in a typical marshall 4x12 with the 4/16 mono option
4 ohms = four 16 ohm speakers in parallel
16 ohms = two pairs of (two 16 ohms speakers wired in parallel) wired in series

the series wiring will sound a little fatter but not as open

 

[korovamilkdud]

Re: 16 ohms versus 8 versus 4

Didn't expect such informational awesomeness in Transformers thread. This is cool.