8 ohm 4x12 vs 16 ohm 4x12 - any difference??

[Lord Toneking]

discuss

 

[mortega76]

Taken from this thread: http://www.vintageamps.com/plexiboard/v ... 0&p=857899

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mixohoytian wrote:can anyone hear the difference in mono?
I mean when it's properly plugged in 8 ohm speaker out to 8ohm cab or 16 ohm out to 16 ohm cab
I've heard there is better bass response out of 16ohm...?



The frequency response of the same model speaker in its 8 ohm and 16 ohm versions will be identical. Speakers are offered in different impedances to provide more options for multiple arrays.

There are some folks who claim that - on certain amps - sound is better off the 16 ohm tap of the output transformer than the 8 ohm tap. I've not heard that myself, so I can't confirm or deny. I tend to prefer 16 ohm speakers as they allow me more combinations (single, dual, quad, full stack) without getting too low of net load.

mixohoytian wrote:looking to put g12h-30's in a 4x12
would like he flexibility of stereo wiring, but that would mean getting 8 ohm speakers...unless I'm mistaken



Could be done several ways. If you wired two 8 ohms in series, they'd pose a 16 ohm load to the amp. If you connected two such pairs in parallel, that'd be an 8 ohm total load.

The way the Marshall Stereo cabs do it, each pair of 16 ohm speakers is wired in parallel, resulting in an 8 ohm load per pair in Stereo mode. The Mono switch combines those two pairs in Series, netting a 16 ohm load.

All depends on what you're trying to accomplish.

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[JakeAC5253]

As the load shown to the head decreases, efficiency increases, but stress on the transformer also increases as it has to keep up at a greater rate of work. Think of it as taking your cars RPM meter to redline (4Ohm) vs driving at low RPM's (16Ohm). Don't get caught up in the 'speakers of a certain ohmage have a certain sound', as I believe it to be mostly bullshit. If something can't be proven electrically, then I take it with a grain of salt. Lower ohm loads should in theory produce more accurate output tones since the amp is operating at closer to peak efficiency.

 

[glpg80]

As the load shown to the head decreases, efficiency increases, but stress on the transformer also increases as it has to keep up at a greater rate of work. Think of it as taking your cars RPM meter to redline (4Ohm) vs driving at low RPM's (16Ohm). Don't get caught up in the 'speakers of a certain ohmage have a certain sound', as I believe it to be mostly bullshit. If something can't be proven electrically, then I take it with a grain of salt. Lower ohm loads should in theory produce more accurate output tones since the amp is operating at closer to peak efficiency.

the first part of your statement is true, the last part is not quite right, i think you're close but are not wording it correctly and mixing personal opinion.

the deal with setting ohms has nothing really to do with the speakers here and everything to do with the output transformer and what is really going on behind the scenes. efficiency measured with impedance ratios is more of power efficiency and less 1 to 1 ratio efficiency. there are natural roll off points with output transformers in their design, the primary impedance which differs transformer to transformer and only suites to meet power tube datasheet standards, and also the purpose of an output transformer in the first place - to convert high voltage low current into high current low voltage.

in car stereo systems the overall power efficiency is indeed a 1:1 ratio and the lower the secondary impedance the better, but in valve amplifiers this is nowhere near the same design.

in these amplifiers the higher the impedance on the secondary the more efficient it is, the lower you go, the more you load the secondary in regards to current source of the primary. you are only adjusting the windings ratio of the secondary itself.

you can hear a difference in mil-spec transformers on which tap you have selected if build tolerances are tight and high quality iron and high quality insulators are used between the windings.

connecting speakers in series parallel or parallel series is only better distributing the source current - however the impedance rules have to be followed for the output transformers secondary windings to not overheat and short.

true output power is complicated. on another forum i have wrote out notes on this in detail but its still complicated to measure what goes in versus what goes out, it is not a simple "the lower the better" rule of thumb here. impedance although measured in ohms, is also dealing with reactances and is an indepedent variable Z - not R like resistance which is also measured in ohms.

 

[steve_k]

Good question and good topic. This may be a job for Mr. Scumback himself, since he is the self-professed Sultan of Scum and may can offer a more technical view....

On a practical level though, at a higher ohm impedance, you are holding back pressure on the amp. Decrease the impedance, you are holding back less on the amp. Unplug the load and the transformer has no resistance and runs away. I wouldn't begin to suggest that I can hear a difference in any amp at various loads, but I can sit down with a few of my amps and clearly tell a difference. Whether it is knowing or imagining, I think an amp at 16 ohm sounds a little smoother and less harsh and a little more compressed than an amp at 4 ohm load. I think it was with my Twin Jet, I was running it with a 16 ohm rear load cab and got dialed in. I put it to 4 ohm and tried it with 2 x 8 ohm 412's with the same speakers and immediately, it lost some of the grunt and compression which was replaced with loos,e hollow and very open tones. The tightness went away.

So, as a rule, I try to go for a 16 ohm load anymore with anything. Some say you can hear a difference in running an amp on the 8 ohm tap with a 16 ohm cab as opposed to running it on the 16 ohm tap. I think once you play and get used to the certain reactions you come to expect between amp and cab, then make any change that affects the looseness or tightness of the amp, you will tell a difference. It may be small, but you can tell.

Steve

 

[JakeAC5253]

Where did opinion come into play? I said more accurate not better. I use an 8 ohm cab, so go figure.

 

[Lord Toneking]

The reason I'm asking is that I have a Splawn 4x12 coming and he usually uses 16 ohm speakers but in my case he only has 8 ohm speakers at the shop right now. I'm anxious for the cab and told him to just go ahead a load it with the 8 ohm speakers

I'm just wondering if I'd be better off waiting for 16 ohm speakers??

I do have a Splawn 2x12 that is 8 ohms and I guess I could run the two together at 4 ohms, but my whole purpose of the 4x12 is to do a wet/dry setup with the 4x12 being my dry cab. So matching the ohms on each cab wouldnt matter being that a separate power amp is going to be powering my 2x12... make sense??

I just want what will sound best..or would anyone really notice?...even a ToneKing like myself

 

[Lord Toneking]

Where did opinion come into play? I said more accurate not better. I use an 8 ohm cab, so go figure.

Arent all Mesa cabs 8 ohms anyways?

 

[glip22]

Not sure if he has changed his mind since this: Have you changed your mind Mr. All that is all in the speaker worlds?


Originally Posted by Braciola
I emailed this question to "the tone doctor" over at Celestion.
Interesting reply....

There are only slight tonal differences between 8 and 16ohm most of which comes from the way the amp interacts with that impedance. Generally a 16 ohm is a little tighter at the bottom end but it is only very slight.
regards
The Doctor

This has been my experience as well. The difference between 8 & 16 ohm speakers is negligible. I think it's one of those "speaker myths" that should be ignored.

I know alot of folks who swear they can tell the difference in tone, but I feel they've based their opinions on old speakers that had manufacturing or other cone/aging differences, and that's how that myth got started.
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[JakeAC5253]

Where did opinion come into play? I said more accurate not better. I use an 8 ohm cab, so go figure.

Arent all Mesa cabs 8 ohms anyways?

I fail to see how that factors into it. Explain to me how saying Mesa on the front changes the science being discussed, and I will answer this question.

 

[steve_k]

The reason I'm asking is that I have a Splawn 4x12 coming and he usually uses 16 ohm speakers but in my case he only has 8 ohm speakers at the shop right now. I'm anxious for the cab and told him to just go ahead a load it with the 8 ohm speakers

I'm just wondering if I'd be better off waiting for 16 ohm speakers??

I do have a Splawn 2x12 that is 8 ohms and I guess I could run the two together at 4 ohms, but my whole purpose of the 4x12 is to do a wet/dry setup with the 4x12 being my dry cab. So matching the ohms on each cab wouldnt matter being that a separate power amp is going to be powering my 2x12... make sense??

I just want what will sound best..or would anyone really notice?...even a ToneKing like myself

I doubt you will be able to tell anything between 16 and 8. And, for what you are doing, running them on separate amps, that is ok. And, whether your cab was 16 or 8, should you decide to run both cabs on the same amp, an 8 and a 16 would have to be run off the 4 ohm tap, as would 2 x 8 ohms. So, you are not losing anything by going with the 8 ohm.

Steve

 

[Vrad]

To me, the 16ohm cab sounds brighter and crunchier. Possibly more responsive.
The 8ohm cab is warmer. Highs are a bit rolled off, smoother.

 

[glip22]

To me, the 16ohm cab sounds brighter and crunchier. Possibly more responsive.
The 8 ohm cab is warmer. Highs are a bit rolled off, smoother.

Less highs in the 8 ohm. 16 uses the most windings of the transformer.

 

[glpg80]

To me, the 16ohm cab sounds brighter and crunchier. Possibly more responsive.
The 8 ohm cab is warmer. Highs are a bit rolled off, smoother.

Less highs in the 8 ohm. 16 uses the most windings of the transformer.

 

[Vrad]

To me, the 16ohm cab sounds brighter and crunchier. Possibly more responsive.
The 8 ohm cab is warmer. Highs are a bit rolled off, smoother.

Less highs in the 8 ohm. 16 uses the most windings of the transformer.

Yes

 

[glpg80]

To me, the 16ohm cab sounds brighter and crunchier. Possibly more responsive.
The 8 ohm cab is warmer. Highs are a bit rolled off, smoother.

Less highs in the 8 ohm. 16 uses the most windings of the transformer.

Yes

Clipman to the rescue!

 

[Vrad]

To me, the 16ohm cab sounds brighter and crunchier. Possibly more responsive.
The 8 ohm cab is warmer. Highs are a bit rolled off, smoother.

Less highs in the 8 ohm. 16 uses the most windings of the transformer.

Yes

Clipman to the rescue!

It's a bird... it's a plane... it's Clipman!

 

[sled]

an 8ohm 4x12 cab comparison versus a 16 ohm 4x12 cab is meaningless.

first off the same speakers can't be used. throw out that test. four 8 ohms speakers can't be wired to 16 ohms and four 16 ohms speakers can't be wired to 8 ohms.

now, a 16ohm 4x12 versus the same set of speakers in the same cab wired to 4 ohms can be tested. likewise, four 4 ohm speakers wired to four ohms versus the same wired to 16 ohms can be tested. the same speakers must be utilized for the comparison.

what's going to happen is an averaging versus additive impedance affect. each speaker's impedance versus frequency response affects the other speakers and what total impedance the amps output sees. a parallel or averaging response is different than a series or additive response. these are very complex interactions.

 

[Vrad]

an 8ohm 4x12 cab comparison versus a 16 ohm 4x12 cab is meaningless.

first off the same speakers can't be used. throw out that test. four 8 ohms speakers can't be wired to 16 ohms and four 16 ohms speaker can't be wired to 8 ohms.

now, a 16ohm 4x12 versus the same set of speakers in the same cab wired to 4 ohms can be tested.

what's going to happen is an averaging versus additive impedance affect. each speaker's impedance versus frequency response affects the other speakers and what total impedance the amps output sees. a parallel or averaging response is different than a series or additive response. these are very complex interactions.

My observations are based on the same cab and the same speakers.
16 ohm GB Reissues
vs.
8 ohm GB Reissues

16 ohm GB's crunchier and brighter
8 ohm GB's smoother and darker

 

[sled]

an 8ohm 4x12 cab comparison versus a 16 ohm 4x12 cab is meaningless.

first off the same speakers can't be used. throw out that test. four 8 ohms speakers can't be wired to 16 ohms and four 16 ohms speaker can't be wired to 8 ohms.

now, a 16ohm 4x12 versus the same set of speakers in the same cab wired to 4 ohms can be tested.

what's going to happen is an averaging versus additive impedance affect. each speaker's impedance versus frequency response affects the other speakers and what total impedance the amps output sees. a parallel or averaging response is different than a series or additive response. these are very complex interactions.

My observations are based on the same cab and the same speakers.
16 ohm GB Reissues
vs.
8 ohm GB Reissues

16 ohm GB's crunchier and brighter
8 ohm GB's smoother and darker

they're different speakers. useless test.