Using highest speaker load for best tone?

[MetalMedal II]

As a New year’s resolution, I’m gonna stop procrastinating and ask this question that’s been bugging me for some time. One of the gear article’s from the November GP Shop Talk discussed speaker impedance and matching to an amp. Fine, been there and I know the basics. The author then states that it’s best to use the highest ohm speaker load that the amp can handle. I don’t want to confuse things, so I’ll just quote it:

“When a transformer is made, it is wound for the largest impedance – the other impedance taps are just a smaller percentage of the whole transformer. So, for example, on a 16 ohm transformer the 8ohm tap would be placed at 70.7% of the full winding. If there were a 4 ohm tap, it would be placed at 50% of the full winding. So if you were using a 4 ohm tap into a 4 ohm speaker, you would only be using half of your transformer! Think of an 8-cylinder engine with 4 of the spark plugs disconnected. It may run, but it won’t be optimum. Using the entire transformer winding means you’re getting full performance from the transformer.”

Is this right? So if I’m using an 8 ohm load for a an amp designed to use 16, 8 and 4-ohm loads, I’m not getting the best potential tone outta it? Cos if this is right, I gotta start rewiring some speakers!
Please discuss. Oh, and Happy New Year!

[Cygnus X1]

My opinion, just stay with a matched load.
Anything else and your playing with fire.

Edit...just using the highest tap as opposed to the lowest-not sure.
I'll have to research it.
I have 16, 8 and 4 ohm cabinets and don't notice a large amount
of difference in efficiency running with same amp.
The biggest difference is in the type of speaker (alnico vs ceramic, voice coil size, etc)
and the type of cabinets.

[DonP]

“When a transformer is made, it is wound for the largest impedance – the other impedance taps are just a smaller percentage of the whole transformer. So, for example, on a 16 ohm transformer the 8ohm tap would be placed at 70.7% of the full winding. If there were a 4 ohm tap, it would be placed at 50% of the full winding. So if you were using a 4 ohm tap into a 4 ohm speaker, you would only be using half of your transformer! Think of an 8-cylinder engine with 4 of the spark plugs disconnected. It may run, but it won’t be optimum. Using the entire transformer winding means you’re getting full performance from the transformer.”

This sounds correct to me.

FWIW, I use the 16 ohm tap on my DSL100 and Laney AOR's.

[Firebird V]

This is true but your Ohms switch on your head needs to be match or be lower or it will do damage. Assuming you have a switchable Oms head.
Your safe combonations would be:

16 Ohm head - 16 Ohm cab. Optimal.
8 Ohm head - 16 Ohm Cab. 70% power output from transformer. this is also good to do if you are running a 100w head in 50w mode because you have cut half power protecting the transformer from a surge)
4 Ohm head into 16 Ohm Cab. 50% power output from transformer

If you are running an 8 Ohm cab and have a switchable Ohms on your head.

8 Ohm Head into 8 Ohm Cab. Optimal.
4 Ohm Head into 8 Ohm cab. 50% power cut. (this is also good to do if you are running a 100w head in 50w mode because you have cut half power protecting the transformer from a surge)

4 Ohm Head into 4 Ohm cab. Only option is to match.

If you run a 4 Ohm head into a 16 Ohm cab you will hear a tonal difference. It sounds brighter and thinner. Sometimes people do this just because they like the sound. It will not harm anything and it does put less stress on the output tranny.

[chrisolson]

After running my Marshall a couple different way (4/4 & 16/16), I like the way it sounds 16/16. Not sure why, but it seems to keep thing a little tighter. Weird. BTW - 100 watt Marshall JVM .

[MetalMedal II]

Thanks for the responses. The article brought up something that I never thought of before and I just wanted what others' experiences were. I'm not rewiring any speaker cabs....yet!

[lhrocker]

If that's the case, does it mean a full stack would never sound it's best since the majority of the time, multiple cabinets are in parallel?

[toddstaples]

I know its a mental block, but Ive always liked my Marshall at 8 Ohm's. (2 16 ohm cabs, or 1 8 ohm cab)

[DonP]

If that's the case, does it mean a full stack would never sound it's best since the majority of the time, multiple cabinets are in parallel?

Correct. Unless you wired them up as 32 ohms with 4 8 ohm speakers each in series.

I think we are really splitting hairs here

[marcus]

Correct. Unless you wired them up as 32 ohms with 4 8 ohm speakers each in series.

I think we are really splitting hairs here

I'm going to have to agree with Don here, this effect has got to be subtle. Unless your output transformer sucks, and we all know amp manufacturers would never install a sub-par transformer, right?

[Cygnus X1]

I'm going to have to agree with Don here, this effect has got to be subtle. Unless your output transformer sucks, and we all know amp manufacturers would never install a sub-par transformer, right?

I use oversized output transformers in my low watt amps.
Rated for 15 watts, the most it will "see" would be 7 watts.

Plugs for 4, 8, and 16 ohms.
(I don't trust switches).
So I can immediately switch between different cabs, and I still don't hear much difference as long as the impedance is matched.

[marcus]

I use oversized output transformers in my low watt amps.
Rated for 15 watts, the most it will "see" would be 7 watts.

Plugs for 4, 8, and 16 ohms.
(I don't trust switches).
So I can immediately switch between different cabs, and I still don't hear much difference as long as the impedance is matched.

This is what I was talking about. With an ideal transformer, there will be no difference.

[markD]

i use the 4 ohm setting on my amps while running an 8 ohm load. i like the way it sounds and i have never had an issue. been doing it for YEARS.

[Robert Burns]

16 ohm VHT 4/12 cab for my left channel is plugged into the 16 ohm output of the amp... 2ea Crate 2/12 cabs at 6.8 ohms on a digital meter
are plugged into the "B" side of the VHT power amp, with the 4 ohm setting chosen. Keep the amp set lower than the actual impedence of
the cab...

[Cygnus X1]

i use the 4 ohm setting on my amps while running an 8 ohm load. i like the way it sounds and i have never had an issue. been doing it for YEARS.

I understand.
Running a 1/2 load usually isn't that big of a deal.
A good OT will take it, but mixing and mussing loads is usually counterproductive at best and risky at worst.

You just have to cross your fingers and hope the designer of the amp figured that mismatch in.

Just as many will take it fine as will give up magic smoke.

Can't say much for others than classic Fender or Marshall, but matching loads is usually the best way to get the most out of the amp.
I know I "design" that way.
(That is a very loose term in the amp world).
I just know what sort of signal it is pushing, what the output tubes like to see, and what OT I put in to accommodate.
The output transformer's very existence is to buffer what the amp puts out to what the load is after all is said and done.