# All other things being equal..



## Robert1950 (Jan 21, 2006)

...What is the output (sound) difference between 4, 8 and 16 ohms???


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## nonreverb (Sep 19, 2006)

If you're referring to tube amps, nothing as long as the impedance of the output transformer and speaker are matched.


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## GTmaker (Apr 24, 2006)

first of all, I love this question.

I have another question...
I have an amp with 4 ohms, 8 ohms and 16 ohms outputs...
I also have a cabinet with (2) 8 ohms speakers...
I can go 4 ohms OR 16 ohms with the speakers. 
Plugged into the appropriate output jacks does this make any difference to the amp, speakers or the oveall tone.
G.

Just one more question..
Do speakers really care if you hook them up in series or parallel..( not talking about total Ohms output)?


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## greco (Jul 15, 2007)

GTmaker said:


> Plugged into the appropriate output jacks does this make any difference to the amp, speakers or the overall tone?


If the impedance matches (which is what you are stating) ...I'm going to say "NO" is the answer to this question.



GTmaker said:


> Do speakers really care if you hook them up in series or parallel..( not talking about total Ohms output)?


Again, I'm going to say "NO".

However, if your speakers are emotional, they might "care" and be elated if wired in series and depressed if wired in parallel (or the reverse).
FINE PRINT: Sorry...I just couldn't resist. I'll buy the coffee next time.


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## keto (May 23, 2006)

Actually, it might make a difference. I forget the tech behind it, and might butcher this explanation badly but someone who actually knows what they're talking about will be along sooner or later. Essentially flowing the charge thru the output of the amp, it might sound differently at 4, 8, or 16, even if going to an exact rated match, because of how the transformer is made. But it is going to be a small difference, possibly imperceptible. Or, maybe you crank it up loud and can clearly hear a difference. Probably depends from amp to amp and transformer to transformer.

Series/parallel, Ima gonna say 'no' also. In that case, it's straight up electricity with no transformer doing any translating so to speak.


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## Granny Gremlin (Jun 3, 2016)

Series / parallel doesn't sound different, and power handling remains the same, but there is an argument for parallel, in that if a speaker goes, you still have another to provide some load. With series, if one goes you'll have an open circuit. Get it quick enough and with most decently robust amps no problem, but if that goes on long enough bad things happen.

A minor consideration, cause when you blow a speaker you'd likely be right there to turn it off, but still.


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## Guest (Oct 23, 2016)

How about size and rated power?
ie, I have a Weber 10" 30 watt 8 ohm that I use with my Traynor 1/4 horse (25 watt).
Would using, say a 12" 60 watt 8 ohm speaker (vintage 30) make any significant difference?
I once had the opportunity to plug it into a 412, 200 watt 8ohm cab and it sounded fuller/louder.


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## Robert1950 (Jan 21, 2006)

Further Question: What would happen if you ran a tube amp rated at 4 ohms into an 8 ohm speaker cab??


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## isoneedacoffee (Oct 31, 2014)

Robert1950 said:


> Further Question: What would happen if you ran a tube amp rated at 4 ohms into an 8 ohm speaker cab??


I was actually advised to do this. Why? I have the new traynor yba1 mod1. It's 40 watts. I replaced the two speakers in my cab for 25w greenbacks (8ohm each) making a 4ohm load. To further protect the speakers I was advised by mike at traynor to use the 8 ohm output from the amp. 

Would you agree that this was sound advice? What is the wattage output difference between the 4 and 8 ohm outputs?


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## High/Deaf (Aug 19, 2009)

Robert1950 said:


> Further Question: What would happen if you ran a tube amp rated at 4 ohms into an 8 ohm speaker cab??


Generally, a 2X mismatch is acceptable (anything but 4:16 basically), unless the amp has some weak components. In fact, Mesa even recommends trying it for tonal variety.

To the original post, it better not. If you hear a difference between two different matched impedance connections, say 4:4 or 16:16, it's probably because of the interconnects. A 4 ohm connection will see more current between amp and speaker and if you are hearing a difference, it's probably because the speaker cable or connectors are adding resistance somewhere. They should sound the same, all things operating correctly.

I think some people think they hear a difference between two matched connections of the same equipment because of confirmation bias and the fact that you can't quickly A/B test it, it takes time to rewire things. People want to hear a difference so they do.


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## nonreverb (Sep 19, 2006)

There is no difference for all intents and purposes. The advantage using a 16ohm system is to minimize line loss. Let's say you have a length of speaker cable that has a 1 ohm resistance across it's length. Plugged into a 16ohm type system, it will have 6% more resistance across the cable. Using the same cable in a 4 ohm system, will have 25% more resistance using the cable. As you can see, in this application, the 16 ohm system is far more efficient. Applying this principle to combo amps or head/babs doesn't really apply or has any real advantage. IMO the different impedances have been kept in production so combinations of speakers can be made to work with amp outputs.


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## High/Deaf (Aug 19, 2009)

Yes, but it takes 250' of average 16ga speaker cable to get 1 ohm of resistance. Most speaker cables should be only measurable in mhos, not ohms. So in practical applications, there should be no difference between a matched 16 ohm or 4 ohm connection, all other things working correctly.


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## Granny Gremlin (Jun 3, 2016)

laristotle said:


> How about size and rated power?
> ie, I have a Weber 10" 30 watt 8 ohm that I use with my Traynor 1/4 horse (25 watt).
> Would using, say a 12" 60 watt 8 ohm speaker (vintage 30) make any significant difference?
> I once had the opportunity to plug it into a 412, 200 watt 8ohm cab and it sounded fuller/louder.


Different speakers will sound different (obviously), but further to that, using a higher wattage speaker (more than double amp output vs about the rating) has the result of (depending on the speaker) greatly reducing (possibly even eliminating) cone breakup. This is great for cleans and articulation/responsiveness, but if you're using a low watt amp so you can be dirty at reasonable volume, cone breakup is a really significant and desirable part of that.

As for the 4x12, obviously the cone breakup thing applies, but further, (again depending to a degree on the speakers in question) more speakers will generally be louder than fewer. The reason is that it will tend to be more efficient and therefore louder.

You didn't explicitly ask, but then there's the issue of driver size. As always, the specific speaker in question makes a difference, but as a general rule, bigger speakers have a larger cone volume and can therefore push more air and therefore reproduce more bass. The trade off is that they are heavier and facing more, shall we call it, wind resistance, so larger drive units tend to be less responsive - you may have heard people say that 15s are sluggish. Other than increasing power handling (not much of a consideration anymore, but back in the day they didn't have a single drive unit that could take more than 40-50 watts) the reason they use multiple smaller drive units in a cab is to get the bass response of a larger speaker, but retain the attack of smaller ones - see the Ampeg SVT and 8x10 fridge - that's what people love about it.


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## Granny Gremlin (Jun 3, 2016)

.


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## Robert1950 (Jan 21, 2006)

Okay, line lose. What would be the difference if you ran a 5w 4 ohm tube amp into a 8 ohm 1x10 cab using a a 5 ft proper speaker cable??


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## greco (Jul 15, 2007)

Robert1950 said:


> Okay, line lose. What would be the difference if you ran a 5w 4 ohm tube amp into a 8 ohm 1x10 cab using a a 5 ft proper speaker cable??


This topic can really get one's head spinning due to the scrambling of one's grey matter.

IIRC...(from GC forum member Wild Bill and the "mice nuts" days) some of the additional factors (not for the "difference" ...but for concerns related to this being hard on the amp) that need to be taken into account are:

How loud are you playing?
For what duration are you playing at the loud levels?
How large/capable is the out put transformer? 

Sorry, I read your _"What would be the difference..." _after formulating my response. Oh well...I'll be more careful next time.


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## Robert1950 (Jan 21, 2006)

To scramble a little more grey matter. What if I was running a 4 ohm 5w tube amp through a Weber Mini Mass Attenuator into a 1x10 8 ohm cab. The amp would be around 7 (2:00). The Attenuator has 4/8/16 ohm switch. Would I it at 4 ohm for the amp or at 8 ohm for the cab???


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## jb welder (Sep 14, 2010)

laristotle said:


> How about size and rated power?
> ie, I have a Weber 10" 30 watt 8 ohm that I use with my Traynor 1/4 horse (25 watt).
> Would using, say a 12" 60 watt 8 ohm speaker (vintage 30) make any significant difference?
> I once had the opportunity to plug it into a 412, 200 watt 8ohm cab and it sounded fuller/louder.


Aside from the great responses of others, another significant consideration when choosing speakers is sensitivity. This is basically a rating of loudness per watt. It is spec'd in db. A speaker that is 3db more sensitive will give you a loudness boost that is roughly equivalent to doubling the power of your amplifier.



isoneedacoffee said:


> I was actually advised to do this. Why? I have the new traynor yba1 mod1. It's 40 watts. I replaced the two speakers in my cab for 25w greenbacks (8ohm each) making a 4ohm load. To further protect the speakers I was advised by mike at traynor to use the 8 ohm output from the amp.


A tube amp will put out it's rated power when impedance matched to it's load. Mismatching will decrease the power delivered a little bit (depending on degree of mismatch). The exact decrease will depend on the particular amp. I would guess in your case maybe 20% decrease. So you will be less likely to reach the 50W that your speakers are rated to handle. (The Traynor is rated to put out 40W clean but can exceed this at high distorted levels)



Robert1950 said:


> What if I was running a 4 ohm 5w tube amp through a Weber Mini Mass Attenuator into a 1x10 8 ohm cab. The amp would be around 7 (2:00). The Attenuator has 4/8/16 ohm switch. Would I it at 4 ohm for the amp or at 8 ohm for the cab???


For the Weber mass, I would think it should be matched to the amp rather than the cabinet. Best to double check with Weber anyway.


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## nonreverb (Sep 19, 2006)

High/Deaf said:


> Yes, but it takes 250' of average 16ga speaker cable to get 1 ohm of resistance. Most speaker cables should be only measurable in mhos, not ohms. So in practical applications, there should be no difference between a matched 16 ohm or 4 ohm connection, all other things working correctly.


More often than not back in the day, PA systems (all manner of public address systems) ran considerable lenghts of wire from amp to speaker hence the 16ohm standard. Many might not realize that there was actually a 32ohm standard as well as the 70 volt high impedance system once upon a time as well. All to address line loss. In other words, 16ohm system is a still used vestigial system introduced several decades ago.


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## sulphur (Jun 2, 2011)

I picked up some Webers a few years ago, a Blue Dog and a Silver Bell.
At the time, I had a fairly bright amp. I was recommended to go with a higher wattage to tame/smooth out the highs.
I think that there's something to that affect on the Weber site somewhere.
I also got 16 ohms to run parallel at 8ohms.

These ended up in my YGL1.
On the back of the amp, it's say "Minimum 4 ohms".
I believe that in the manual it recommends 8 ohm and there was an 8 ohm GB in there stock.

So, the Blue Dog went into the combo and the Silver Bell went into the extension cab.
As these are 16 ohm speakers and are run parallel when the extension cab is plugged in, so they run at 8 ohms combined.
When I'd just run the BD in the combo, there's disernible attenuation on the output level.
Not huge, but quite a noticable difference.


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## nonreverb (Sep 19, 2006)

There would be as 16ohm is 100% mismatch. The increased reflected impedance on the power tubes would slightly lower their output and alter the sound a bit. What happens is the transformer absorbs the higher swing of the AC voltage which is known as flyback. At high settings, this flyback voltage can be so great (over 1000VAC in some cases) that it can literally punch a hole through the transformer primary winding insulation.....Marshalls are notorious for this problem with higher impedance speakers on a lower amp impedance setting. Having said that, you're probably safe.


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## sulphur (Jun 2, 2011)

I tried it at home once, really to just try each speaker on its own.

I did it twice at band practice, by accident. 8)


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