zeusecho

If you can choose the impedance of your cab, are there are reasons to use either the 4ohm, 8ohm, or 16ohm outputs on say a DSL50 or any applicable tube amp. Is it preferred to use one over the other?

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Doomhawk

you know i had a bunch of friends that always wired their cabs to 4 ohms. they always said it was more ballsy. i never heard a REAL difference. its just that 4ohms would be guitar signals - path of least resistance to the speakers. but if you like to hook up more than one cab to you rig i would always go with the highest resistance 16ohms. because if you had a 4ohm cab and wanted to hook up another. well it would be hard to find another 4 ohm guitar cab just laying around. and your amp doesn't have a 2 ohm tap.

PaoloJM

Hmmm, that doesn't seem to make a whole lot of sense to me.
Were your friends setting the cab impedance to 4 ohm and using the 16 ohm setting on the amp or what way around was it? I dont understand the piece about path of least resistance?

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zeusecho

Yea I thought the rule of thumb is the greatest efficiency with matched impedance between amp output and load. So technically it should not matter which setting is used as long as the amp matches the speakers.

But the reason I asked is becuase I heard people say the prefer one over the other so I was wondering if it was related to tone or amp performance at all.

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PaoloJM

To the best of my knowledge you are correct. Mismatched impedances will affect the tone as the frequency response of the amp is designed with the correct load intended to be attached. An incorrect load will skew this response and alter the tone but is also quite likley to damage your amp, particularily if the mismatch is large.
I dont believe different settings make any difference on the amp performance (cabinet type is a different area) once the impedances are matched but maybe there's something I'm missing...

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Rev2S

Hey zeusoecho. I was just reading about what you are asking about...here is one person's opinion on it below. Personally, I am going to run my two 8 ohm speakers in parallel at 4 ohms (2x12).

"Using medium to high gain OD as a reference

Series wiring- mid/upper mid and high end emphasis generally, smoother high freqs generally due to damped top end highs in the 5 to 6k range, less fizz. Additional tonal changes are slightly spongier attack and altered OD character, more complex and timbrally rich with more overtones ala the mid and top end emphasis.

Parallel wiring- low end and lower mid emphasis with more top end high sparkle or fizz, depending on the speaker and rig that can make the high end raspy or harsh to some. Low end is emphasized due to increased damping between 2 12" speakers in parallel, generallly tighter and more thump.

Think about how low end and sub cabs for Pro Sound Sys are parallel for better bottom due to coupling or dampening if in the same cab, it applies universally

Its impossible to predict how your rig will sound to your liking with either, try them both.

I had the fizz in my amp and wanted a smoother top using the same speaker. The Fizz can be that busy bee hive above your sound that robs your tone of clarity with medium or high gain tones and fast playing on the high strings. Clean or low gain OD tones are a different story and IMO parallel is better but since I mostly play with medium to heavy OD, and OD has the most potential to be painful if not as pleasing as it could be, I go for harder but smoother OD, more old school if you will.

I now use 2, 8ohm Series wired 12" speakers to get a more present upper mid and smoother top end OD with less harshness after trying 2 16ohm in parallel for 8 and 2 8ohm in parallel for 4ohms. When you think of speaker power handling just be concerned that your speakers can handle your ampos output in total but dont be afraid to reduce headroom if you want earlier onset of OD ala Speaker Breakup for a lower volume OD

You can generalize that more powerful speakers have later onset of breakup and vice versa which means you may need to be louder to get to X amount of OD, ignoring the tonal differences for the moment.

Just another aspect in addition to Series versus Parallel wiring.

Another observation and its my opinion but my ears tell me-

Parallel- for heavier OD tones, more modern tone as in todays tuned down uber bottom tones with raspy highs, tighter thump think Tool etc

for cleans, more headroom and usable travel on the guitar pot, more high end sparkle in the 5 to 6k range since the parallel spkr coil config means the extreme high end is not attenuated through each coil in series

more hifi sounding in general with bottom and very top end emphasis

Series- more vintage flavored with less bottom more mids and top end but not as extended into the Presence range of 5 to 6k more suitable for shred where you spend much time on strings 1, 2 and 3 etc. speed picking etc. Too much presence and its Razer Blades to the ears

Less headroom overall meaning less clean and its dependent on the rig of course


P.S. When it comes to clean or light OD to some medium tones, the results may not play out as I have described since the speakers are probably not in breakup.

My observations on Series and Parallel differences were made using medium to high OD tones and then a clean tone test simply by bypassing any OD pedals, backing down guitar pot. The same 2 tests were done with and without pedals for comparison and to eliminate any pedal coloration.

Parallel was 1st- OD was ok and clean was very nice for being able to get to scream with just a turn of the guitar pot, not channel switching

Series- OD improved dramatically for harder styles and tones but clean suffered, oh well


Try all and nay config in every which way to find the best for your rig and tastes"

I hope this helps...

poeman33

I remember reading an article that explained scientifically the tonal differences between 16 , 8 and 4 ohm cabs, but damned if I can find the article now. To over generalize, a 16 ohm cab will sound brighter. I chose an 8 ohm 4x12 for two reasons. 1) because it sounds a little warmer to my ear than a 16ohm cab, and 2) because I can use it with other amps that only have 8ohm outputs, should I ever get a Fender again for example.

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joeellistsl

The path of least resistance. The term ohm refers to the electrical resistance. The higher the number, the more resistance there is (i.e. 16 ohm more resistance than 8 ohm, etc.). I am not an electrical guru, so I can't give a more detailed explanation. I would set the value to what the manufacturer recommends, especially if it is still under warrenty. It may not damage your amp, but why take a chance.

Rev2S

Here is an thread from The Gear Page:

4, 8, 16 ohm taps - tone difference? - The Gear Page

PaoloJM

I know what the path of least resistance is it's just that I dont see how it is relevent here.

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Doomhawk

to answer your question PaoloJM...obviously they matched the impedance. it wouldn't be very smart if they didn't. it is relevant because he was asking what people prefer to use, and the differences between the ohm ratings. my answer was i didn't "really" hear a difference in the sound. that ohms are a measurement of resistance and that all the differences to me, relative to ohms, is how many speaker cabs you could hook up to your head.

JohnH

I havn't tried these tests to hear the sound difference. But from an electrical point of view, I think theres an advantage in using 16Ohms rather than 4Ohms, in terms of stress on the transformer.

So long as the impedances match, then the tubes are happy, and so are the primary windings. But with the secondary windings that drive the speakers, at four ohms, there is twice as much current flowing than at 16 ohms for a given power output (P=I^2xR). That means more power dissipated in each inch of the windings, and it's all in just 1/4 of the secondary winding length as compared to that used for 16Ohm output. I think that adds up to the same total power loss in the windings, but conncentrated into just 1/4 length.

Presumably transformers are designed to work like this and its all OK, but the 16Ohms seems more relaxed theoretically.

John

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PaoloJM

That makes sense to me, as you say the transformer design probably allows for this.
There is also the issues of mutual inductance in the cab itself. If mutual inductance was occuring in a cab then parallel wiring would tend to reduce it's effect whereas series wiring would tend to increase it. If that was the case then speakers wired all in parallel would tend to have a lower resonant peak than those wired all in series and series parallel would be somewhere between. If this was the case then the 4 ohm setting may be seen to have a slightly more bassy response. This might explain the findings in Revs post.

However I dont know enough about cab design to know if mutual inductance actually does ocuur in a cab. Does anyone else know?

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thegaindeli

The purest, simplest format is the single-speaker cab, where the lone driver presents no interference with its own tonal character. No two speakers of even the exact same make and size sound exactly the same (these are electromechanical components with multiple moving parts and numerous variables within their own makeup), and putting two or four speakers into the same cab will introduce a degree of "phase-cancellation" that affects the sound the cab produces as a whole. In fact, the slight "out-of-phase" issues presented by cabs with two or four identical speakers often work to improve a cab’s overall performance by smoothing out any harshness or woofiness that the same speakers might present individually.

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RachelMorgan

Sounds to me that it's just personal preference. Just make sure the speakers match up with the amp.

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zeusecho

Thanks for all the comments guys. Cheers.

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Marshall DSL50
H&K Switchblade 50W Combo
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Gibson LP Custom
ESP MH-301
Merz Custom Acoustic
Taylor 355ce 12 String