Speaker ohms Tone ?

PGLive

True Tone will only be achieved in Heaven
Gold Supporting Member
Messages
772
Hi All,
In an 8ohm amp (5e3) will I hear tonal difference if I run a 16 ohm speaker?

Thanks!
 

Sherwood

Member
Messages
490
The theory: no tone change.

The actual fact: Yes and no. I'll explain..

Your Output Transformer (OT) will perform differently at diffrent speaker loads.

Keep in mind that on a guitar tube amp the OT is the biggest tone "color" generator:

1- Lets say your amp has 16-8-4 ohm taps (those are your OT's out jacks) and you plug in a 16 ohm cabinet at the corresponding 16 ohm jack. You're going to get all of your OT windings working to produce your tone. That usually means a smoother and harmonically rich tone;

2- Now, lets say you plug in a 4 ohm cabinet at the corresponding 4 ohm jack (not using the 8 nor the 16 ohm taps). Your OT now is taped, not all windings are working to produce signal (tone). That usually means more volume with less compression and a generally stiffer feel to the tone;

3- Now, if you create a mismatch by conecting that 16 ohm cabinet at the 4 ohm output tap/jack you're going to get a volume drop, wich generally bring a little more sag back into the tone. Still, not all of the windings of your OT are working to produce your tone and you may find you like the greater harmonic content of the matched 16 ohm tap better.

Theoretically, all things in your amp's circuitry are connected receiving energy and creating tone it was designed to produce, but the final and key elemento, the OT, will perform differently at varying speaker loads.

By all means, experiment... not at home volume, but at rehearsal volume.

I alway prefer the feel my amps produce at the maximum impedance my amps OT have and matched impedance cabs. But that's me..

A disclaimer: If you plug in a cabinet with lower load (ohm) than the corresponding amp's jack, you'll reduce the lifespan of your tubes and possibly overheat your OT. Damage may happen after some time doing so. But if you do that on a transistor amp, you'll blow it at once and for good.
 

ironman28

Member
Messages
627
:facepalm
No theory required. A mis-matched impedance on the amp out put will result in a reduction of power and a reduced bandwidth. In most cases this is audible. Some amp manufacturers use mismatched loads as a "tone" control to be set however you like. A properly designed and built tube amp will have no problems with mis-matched loads. There are some poorly designed transformers in vintage amps that are more likely to have problems with high impedance mis-matches.
Whether or not a 16 ohm tap has a better tone is purely subjective. The 4/8/16 ohm taps are there for your convenience. All the windings in the transformer are energized regardless of what tap is used. If the "full windings" myth had any validity, amp builders would still be using OTs with a single secondary for the best tone.
 

BlueRiff

Senior Member
Messages
7,745
:facepalm
No theory required. A mis-matched impedance on the amp out put will result in a reduction of power and a reduced bandwidth. In most cases this is audible. Some amp manufacturers use mismatched loads as a "tone" control to be set however you like. A properly designed and built tube amp will have no problems with mis-matched loads. There are some poorly designed transformers in vintage amps that are more likely to have problems with high impedance mis-matches.
Whether or not a 16 ohm tap has a better tone is purely subjective. The 4/8/16 ohm taps are there for your convenience. All the windings in the transformer are energized regardless of what tap is used. If the "full windings" myth had any validity, amp builders would still be using OTs with a single secondary for the best tone.
One question - if OP uses 16 ohm speaker against an 8 ohm output - will he half the wattage of the amp?
 

PGLive

True Tone will only be achieved in Heaven
Gold Supporting Member
Messages
772
Thanks all..

I figure if you are going up in ohms the tubes would run less hotter, thus, change in tone..
 

Sherwood

Member
Messages
490
:dunnoSome years ago Guitar Player Magazine published a great article from Gerald Weber on this subject, where he states that although the output transformer is fully energized all the time the amp is "on", by tapping it at a fractional impedance you are using less of it.. hence there might be a difference in feel and tone.

I clearly hear a difference. And it may be a good or bad one depending on what you're after. So, by all means, experiment.
 
Messages
7,833
A larger load than expected is going to give you a middier tone. Lower impedance drivers are usually brighter in general.
 




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