a matter of ohms

[Sgt.]

I was wondering when you have to match a speaker to an amp you look at ohms. 4, 8, and 16 ohms are common with guitar speakers/amps. Why do we have speakers in different ohm ratings? The answer I think lies in the number of windings around the magnet ... the 16 ohm speaker is going to have more windings and I assume therefore that a 16 ohm speaker is hotter than the 8 ohm version (all things such as wattage considered equal).

Then there are humbucker sets with ohm ratings and mismatched so the bridge pu is hotter than the neck pu ... again the bridge pickup is going to have more windings and is at a higher ohm rating and therefore hotter?

Is that basically the gist of the 'ohm' rating ... the number of windings around the magnet determining how 'hot' the speaker or pickup is? help ... i'm completely eletronically illiterate!!!

[Guest Farnsbarns]

I was wondering when you have to match a speaker to an amp you look at ohms. 4, 8, and 16 ohms are common with guitar speakers/amps. Why do we have speakers in different ohm ratings? The answer I think lies in the number of windings around the magnet ... the 16 ohm speaker is going to have more windings and I assume therefore that a 16 ohm speaker is hotter than the 8 ohm version (all things such as wattage considered equal).

Then there are humbucker sets with ohm ratings and mismatched so the bridge pu is hotter than the neck pu ... again the bridge pickup is going to have more windings and is at a higher ohm rating and therefore hotter?

Is that basically the gist of the 'ohm' rating ... the number of windings around the magnet determining how 'hot' the speaker or pickup is? help ... i'm completely eletronically illiterate!!!

 

No, you could almost say the opposite, an 8 ohm speaker could be said to be "hotter" than 16 ohm. Running an amp with the lowest load it can take will generally equal more sound but it isn't really that simple either. You'll get all sorts of relies here, my advice would really be to buy a good book or read lots of inline articles (not forum posts) and educate yourself.

[Ryan H]

(Paraphrased from Jeff Bober (Budda Amplification Co-Founder, EAST Amplification founder) in his Premier Guitar article in June of 2010)

 

"A 16 ohm speaker uses a thinner, lighter wire with more turns on the voice coil than an 8 ohm speaker. The extra turns increase it's sensitivity to high frequencies due to inductance. So by nature, a 16 ohm speaker will sound brighter than an 8 ohm speaker of the same model."

 

-Ryan

[Riffster]

Then you add the fact that the 16 ohm tap uses more winds in the output transformer.

[Valeriy]

An effect from ohms , here, there, everywhere is different :)

 

For guitar pickups this is not very significant, here is more significant as that: the number of windings, the force of magnet, the width of pickups as, for example, the width of a single coil pickup is narrower than that one in a humbucker, accordingly, they are very different in the sound.

[Sgt.]

An effect from ohms , here, there, everywhere is different :)

 

For guitar pickups this is not very significant, here is more significant as that: the number of windings, the force of magnet, the width of pickups as, for example, the width of a single coil pickup is narrower than that one in a humbucker, accordingly, they are very different in the sound.

 

I just wondered why we even have choices when it comes to impedance, but Ryan H.'s answer is the best explanation we have yet.

I know simple stuff like matching a speaker to an amp impedance is important (more important to solid state, less important to tube amps), but the ohm is everywhere guitar electronics are involved ... pickups, pedals, speakers, amps, ... I'm not so sure it matters too much outside of matching the speaker to the amp.

[Guest Farnsbarns]

I just wondered why we even have choices when it comes to impedance, but Ryan H.'s answer is the best explanation we have yet.

I know simple stuff like matching a speaker to an amp impedance is important (more important to solid state, less important to tube amps), but the ohm is everywhere guitar electronics are involved ... pickups, pedals, speakers, amps, ... I'm not so sure it matters too much outside of matching the speaker to the amp.

 

The Ohm is a unit of resistance (aka impedance). Every component in every electrical circuit, right down to every length of wire has some resistance so it is inevitable that you will see it a lot.

[Valeriy]

Generally, may seem strange, however a matter of ohms may be important in jack connectors etc B) . In usual inexpensive jacks contact-cleats are often a non-monolith with a jack, and as by means of a screw or a rivet, i.e. by means of a touching. Over time, it is oxidized, the sound may be degraded dramatically because of that.

 

Of course, it is possible to buy an expensive jack, but if it is necessary many jacks for a home studio etc? Well...… I just treat slightly these contact-screws by means of soldering at once as I buy and after that they works long and well and the sound too .

[rocketman]

Or you can use superconducting materials to make a 0 Ohm speaker. Read this (warning geek stuff).

[capmaster]

(Paraphrased from Jeff Bober (Budda Amplification Co-Founder, EAST Amplification founder) in his Premier Guitar article in June of 2010)

 

"A 16 ohm speaker uses a thinner, lighter wire with more turns on the voice coil than an 8 ohm speaker. The extra turns increase it's sensitivity to high frequencies due to inductance. So by nature, a 16 ohm speaker will sound brighter than an 8 ohm speaker of the same model."

 

-Ryan

For inductance, the opposite is fact. It would come into account for speaker impedances higher than a few kiloohms due to parasitic and stray capacitances - like with magnetic guitar pickups and inferior output transformers.

 

The skin effect might make a difference on theory, but cables are affected much more by it than coil wires and still won't cause problems within the human audio frequency range.

 

Then you add the fact that the 16 ohm tap uses more winds in the output transformer.

There should be no problem when designed well, used in a well-designed amp circuitry and loaded properly. Fine audio frequency transformers won't affect tone audibly, and most problems will occur in the bass range, if at all.

[badbluesplayer]

The reason speakers are made with different impedances is to be able to accomodate amplifiers with different requirements, and at the same time, offer a variety of speaker arrangements, like one, two or four speaker cabinets.

 

The math works well with 2, 4, 8 & 16 ohms drivers. [thumbup]

[Riffster]

Then you have the fact that that speaker impedance is nominal not actual, because impedance fluctuates when in use.

 

We all know that if you measure the ohms on a speaker you will not get the nominal value.

[Riffster]

There should be no problem when designed well, used in a well-designed amp circuitry and loaded properly. Fine audio frequency transformers won't affect tone audibly, and most problems will occur in the bass range, if at all.

 

I did not think it was a problem at all. The sound is however different.

[capmaster]

I did not think it was a problem at all. The sound is however different.

Sorry, problem was the wrong word, no offense. The different sound, however, is likely to be caused by the different mass of the coil rather than any other property. In so far any power amplifier with a low damping factor will contribute to a different tone. All the different mechanical resonance peaks and notches of the speaker driver will make for a different tone then.

 

For several Marshall JCM 800 and JCM 900 100 watt heads I can say that their transformers work closely the same at different loads. Operating four 16 ohms speakers in parallel through the 4 ohms leg creates the same sound as using two pairs of two of speakers in series connection each driven in parallel by the 16 ohms output.

 

A similar test with Acoustic and Fender amps was a bit flawed - they just offered 4 or 8 ohms outputs, and the different number of speakers affects volume and tone even if acoustically separated. More power makes poweramps and power loudspeakers adding more odd-order harmonics, so the sound will forcibly be more trebly. Since the amp's reaction is different from that of the speakers - the latters of same build, of course -, a valid comparison seemed impossible to me.