Amp head > 8, or 16 ohms.

[Helmholtz]

If one speaker has a number that is double the other, then I was wondering if the voice coil was double the wire thickness, or I dont know cone thickness double ( wild guess but you get the idea ), or double the number of coils around the centrepiece thing. In which case, I would think there had to be a significant difference.

Now that's a different question.

Assuming the same speaker type, a 16 Ohm voice coil will have more turns of thinner wire compared with an 8 Ohm voice coil.
In some cases this will result in a slightly different frequency response.

I've seen published speaker frequency responses showing a little difference betwee 16 Ohm and 8 Ohm versions.
Typically differences are small and there's no general rule I'm aware of.

OTOH, speakers are no calibrated precision instruments and I would expect some sound variation even between different individual speakers of the same model and impedance.

[catalin gramada]

Now that's a different question.

Assuming the same speaker type, a 16 Ohm voice coil will have more turns of thinner wire compared with an 8 Ohm voice coil.
In some cases this will result in a slightly different frequency response.
.

Hey Helm, now that.s a interesting statement and I wonder if the damping factor is affected as well in a significant way please ?

[Helmholtz]

Hey Helm, now that.s a interesting statement and I wonder if the damping factor is affected as well in a significant way please ?

Damping factor would only be affected when "mismatching".

[J M Fahey]

If one speaker has a number that is double the other, then I was wondering if the voice coil was double the wire thickness, or I dont know cone thickness double ( wild guess but you get the idea ), or double the number of coils around the centrepiece thing.

Voice coil DCR which basically defines impedance follows a Cubic ratio; in this case a 16 ohm Voice Coil will use "third root of two" less diameter compared to an 8 ohm one, so 26% thinner wire, 26% more turns, keeping everything else the same.

Since Guitar speaker voice coils always have 2 layers, net effect will be copper weight will be lower and "pushing" force will be higher, for same driving current, so *acceleration* will be higher (imagine a more powerful less weight engine in a motorcycle) , perceived effect means speaker will be "snappier", bolder, brighter, more "in your face", all "typical" characteristics often attributed to Celestion speakers.

Their maintaining "outdated" 16 ohm impedance partly explains that.
Well designed large magnets certainly help.

I´ll post excellent Italian Jensen curves, showing exact same speaker in different impedances; the advantage at mid high frequencies is easy to see :



By contrast, 4 ohm speakers are dull, compared to same 8 and 16 ohm versions.

PS: you didn´t yet answer exact Celestion speaker you have.

[Helmholtz]

Zollner measured SPL differences of 5dB and more at some frequencies between individual Celestion 8 Ohm speakers of the same model.

[Sea Chief]

J M Fahey thanks for this very comprehensive reply, I wasn't expecting such detail.. but it's useful even if I can't glean much understanding from it.. apart from a very vague outline of the answer.

My celestion, is a 1973 30w, 16 ohm greeny looking, or grey/ green back, G12H. "75 hz bass response" it says too.. whatever that means.

Thanks, SC

[Chuck H]

You know... I'm still not even clear what the goal is here.

SC, are you wanting to know the difference in tone with a mismatch of ohms presented to the amp? Do you want to know if, say, two 4 ohm speakers wired in series sounds different from two 16 ohm speakers wired in parallel? Do you want to know if voice coil construction for different ohm spec speakers makes the speakers sound different? (<and in this case would that caveat matching the load to the amp?) Do you want to know what happens if you wire two speakers of different ohm specs in the same amp?

Do you just want to become instantly expert on the matter so there are NO questions??? (<impossible) Because most of the above has been alluded to in query or incidentally covered in responses.

If we knew your specific circumstances and goals clearly outlined this would be much easier. The thread seemed to start with something more specific and then drifted in all directions peripheral. It's sort of like the ICP thing with "Magnets!?! How do they work?" They're not going to get it. To them it's magic. Please try not to ask questions you really don't want the answers to because of the work it might take to understand them. It's very frustrating for the experts who have many years of experience. Concise answers are easy enough for them but it's impossible to distill their level of understanding into a post.

[Sea Chief]

You know... I'm still not even clear what the goal is here.

SC, are you wanting to know the difference in tone with a mismatch of ohms presented to the amp? Do you want to know if, say, two 4 ohm speakers wired in series sounds different from two 16 ohm speakers wired in parallel? Do you want to know if voice coil construction for different ohm spec speakers makes the speakers sound different? (<and in this case would that caveat matching the load to the amp?) Do you want to know what happens if you wire two speakers of different ohm specs in the same amp?

Do you just want to become instantly expert on the matter so there are NO questions??? (<impossible) Because most of the above has been alluded to in query or incidentally covered in responses.

If we knew your specific circumstances and goals clearly outlined this would be much easier. The thread seemed to start with something more specific and then drifted in all directions peripheral. It's sort of like the ICP thing with "Magnets!?! How do they work?" They're not going to get it. To them it's magic. Please try not to ask questions you really don't want the answers to because of the work it might take to understand them. It's very frustrating for the experts who have many years of experience. Concise answers are easy enough for them but it's impossible to distill their level of understanding into a post.

Hi Chuck, Ive been as clear as I can be in #1. G1 as I stated, is spot on, which means it has to be clear enough ( but if confusion remains, his summing up of my q is just a few posts above ).

The thread expanded in a very natural way; I asked a q, & such comprehensive answers came by that further aspects could then be thought of/ considered. But if my innitial q is not understood, then yes you may find it hard to follow I guess.

Ok I'll try & rephrase my q.

----

You see I innitially had the idea of buying an ac30 head. It has two output ports. 8 and 16. I have a 16 ohm speaker. I know that ac30's as a rule have two speakers, going into a single 8 ohm output. But forgetting the twin speaker aspect, as this doesn't factor in, due to my having only one speaker. N/ A.


Ok my q is perhaps simplified thus: what is the difference if i had an identical 8ohm speaker, & i plugged it into this amp's 8 ohm port..................

vs my 16 ohm speaker plugging it into the 16 ohm port? (as i asked in line 1 of #1). SC

[pdf64]

...I know that ac30's as a rule have two speakers, going into a single 8 ohm output. ...

Vintage AC30s typically have a pair of 8ohm speakers, wired in series. They connect to the common and 16ohm terminals of the 3 way block on the preamp chassis, below the input jacks.
I suppose that theoretically, a 30W G12H should cope as well as a pair of 15W Blues.
Vintage AC30s only tend to manage about 25W cleanish, low 30s overdriven.
In the case of the latter, my money would be on the Blues outlasting the G12H though.

[Sea Chief]

Vintage AC30s typically have a pair of 8ohm speakers, wired in series. They connect to the common and 16ohm terminals of the 3 way block on the preamp chassis, below the input jacks.
I suppose that theoretically, a 30W G12H should cope as well as a pair of 15W Blues.
Vintage AC30s only tend to manage about 25W cleanish, low 30s overdriven.
In the case of the latter, my money would be on the Blues outlasting the G12H though.

Hi pdf. Ok I hadn't thought of the max wattage aspect of a single 30w vs a pair of 15w. I wasn't really factoring this wattage aspect into my Q.

It was really simply what is the difference between a 16 oh speaker into any amp's 16 ohm port, vs an identical ( apart from the 8 and 16 difference) 8 ohm spkr into same the amp's 16 ohm port. Lets say both speakers rated @ 50w, the amp 30w.

I really just meant what would I hear, playing guitar. Anything? Half the volume? Twice the volume? Some noticeable tonal difference? No noticeable difference? Twice the bass? Half the bass? ( im only throwing into the hat vague ideas of what an answer could be).

One answer might be 'less bass with a 16 ohm spkr' from the replies... but I'm not sure if this is correct. Maybe it's not such a simple Q then or something.

Thanks, SC

[uneumann]

[QUOTE= What is, or what would be the difference between an amp head -with two output ports, 8, & 16 ohms- going into an 8 ohm speaker ( using the 8 ohm port), vs a 16 ohm speaker ( going into the 16 ohm port) ? [/QUOTE]

That's the question that was posed. I think it's pretty clear and Fahey answered it clearly... In summary, he made two main points.

1 - there is no volume difference. Both conditions provide the same room volume at the same amp/guitar settings. Both cases produce the same power output from the amp to the speaker.
2 - the 16 ohm speaker may sound slightly brighter (more treble) than the 8 ohm speaker (how much depends on the speaker type/brand/model).

So - to reiterate - there is no significant difference between the two cases.

I'll add my 2 cents... the treble difference is usually minor (IMO) and can be compensated for with a slight boost or cut of the amp treble control.
Also, the reason the amp has two ports (8 and 16) is so that you can plug in whatever type (8 or 16 ohm) of speaker you happen to have. It's a convenience. No matter what speaker you have, it can be used with the amp.

[Chuck H]

See,.. Now,.. This is what I'm trying to clear up.

First:

what is the difference if i had an identical 8ohm speaker, & i plugged it into this amp's 8 ohm port..................

vs my 16 ohm speaker plugging it into the 16 ohm port?...

Then:

what is the difference between a 16 oh speaker into any amp's 16 ohm port, vs an identical ( apart from the 8 and 16 difference) 8 ohm spkr into same the amp's 16 ohm port.

These are two different questions. One scenario keeps the amp matched to the load and the next creates a mismatch between the amp and the load.

[nosaj]

See,.. Now,.. This is what I'm trying to clear up.

First:



Then:




These are two different questiont s. One scenario keeps the amp matched to the load and the next creates a mismatch between the amp and the load.

Its like the difference between driving your car around town in 1st gear(non matched load) and driving around town with the selector on D(matched load) Both get you where you want to go but the engine(amp) works harder wearing out faster.
nosaj

[Chuck H]

Its like the difference between driving your car around town in 1st gear(non matched load) and driving around town with the selector on D(matched load) Both get you where you want to go but the engine(amp) works harder wearing out faster.
nosaj

This ^^^^^^^^^^^^^^^^^^^ in the case of a higher mismatched load. I'll add that in the case of a lower mismatched load it would be like driving around town stuck in 3rd gear.

Tonal differences would be a change in volume (it will be lower) and then any reactions from the amp itself due to operating under less than ideal circumstances. The "feel" of the amp will be different. Though not much and mostly at or beyond full output power (which is lower with a mismatched load regardless if it's high or low).

[Sea Chief]

See,.. Now,.. This is what I'm trying to clear up.

First:



Then:




These are two different questions. One scenario keeps the amp matched to the load and the next creates a mismatch between the amp and the load.

No, there is no discrepency. They are exactly the same question. One is just reitterating the previous, to be doubly clear as to what I am asking. Ijust don't understand how you can possibly read any difference. They both keep the amp matched to the speaker.

----

You are assuming I am asking what might be the difference with a 16 ohm spkr going into the 16 port, vs the same spkr going into the 8 port.

I am not.

Furthermore I am being as clear as I can possibly be, to specifically - not - be asking this.