Wiring a 2-12" cab - is series or parallel brighter?

scottcw

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Which produces a brighter tone when wiring a 2-12" cab - series or parallel?

Also, I have 2 16 ohm speakers. Is it safe to wire in series for a 32 ohm load if my amp only has an 8 ohm output jack?
 

Grumpyfatman

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32
Parallel seems to have more bass and treble. Series seems a little warmer. I've read this on other boards but I also did a bit of testing on my own. My testing was done with 2 8 ohm V30s in an open back Egnater TOL 100 combo amp. In parallel it's 4 ohm, in series it's 16 ohm. Same speakers, different tap on the output transformer. Not an exact scientific test though because there are usually differences in tone between taps on the OT. Different amounts of windings on the tranny make for greater inductance and therefore varying amounts of treble.

If your amp is a tube amp I wouldn't mismatch that far. If you're using a solid state power section it would be OK but it won't be as loud.
 

HKGuns

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92
Huh?

How you wire them up is based on the OT not the tone you're after. Output impedance isn't brighter or darker. It is different.

8 to 32 ohm? Only if you like buying transformers!
 

alaskagrown

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284
You could wire different speakers differently to get the same impedance, for example two 4 ohm speakers in series or two 16 ohm speakers in parallel are both 8 ohms. I don't know about the sonic difference, but I'd assume wiring in parallel would be better because in series, you've got a voltage drop across the first speaker, so the second speaker isn't getting as much and they're mismatched.
 

scottcw

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That being said, you should try to match impedences. So series would be best in your application 2-16 ohm series for 8 ohm load.
Wiring in series doubles your impedance. 2-16 ohm in series = 32 ohms.
 

retrobob

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2,326
With some amps you can get away with a 50% mismatch.
But an 8 ohm amp with 32 ohm load is a way big mismatch and a disaster waiting to happen. Hook the two 16 ohm speakers to 8 ohms.
 

KeithC

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Is there a power handling difference with parallel or series?

I know running a 40 watt amp in parallel into 2 speakers splits the power at 20 watts per speaker.
Is it the same thing when wiring in series?

FWIW I have wired the same amps and speakers both ways and my ears couldn't hear any tonal differences.
But, I was just wondering about the power thing!

Sorry to semi hi-jack :AOK
 

sickboy79

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12,724
IMO - with the same cab - parallel is brigher and tighter than series wiring. I base this off wiring a vintage Marshall 4x12 with G12H30s (16 ohm each). My ears found that paralled yielded a tighter bottom, clearer highs and overall sound. This was wiring the cab to 4 ohms. Series/parrel wiring (my cab to 16 ohms) seems to have a sweeter and warmer sound. The bottom isn't as tight (but not loose by any means), more midrange, and sweeter/warmer top end. And it also depends on the amp in question that you are using with the cab. Both wiring schemes have their advantage. Use your ears for what you like best.
 

hamfist

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1,595
but I'd assume wiring in parallel would be better because in series, you've got a voltage drop across the first speaker, so the second speaker isn't getting as much and they're mismatched.
I'd always assumed this is a myth.

When you wire up light bulbs in series, you don't get the "first" in the circuit being brighter, followed by all the others in the circuit getting progressively dimmer. My understanding is that speakers (or light bulbs) in a series circuit all experience exactly the same voltage and current.

And to anyone who actually knows about these things - please feel free to comment !
 

Electric I

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3,374
I'd always assumed this is a myth.

When you wire up light bulbs in series, you don't get the "first" in the circuit being brighter, followed by all the others in the circuit getting progressively dimmer. My understanding is that speakers (or light bulbs) in a series circuit all experience exactly the same voltage and current.

And to anyone who actually knows about these things - please feel free to comment !
Light bulbs in series, if they're of equal wattage, will draw the same current & have equal voltage drops. The same principles apply for inductors (speakers) as well.
 

rockon1

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12,465
Which produces a brighter tone when wiring a 2-12" cab - series or parallel?

Also, I have 2 16 ohm speakers. Is it safe to wire in series for a 32 ohm load if my amp only has an 8 ohm output jack?
No its not safe to run your 8 ohm amp at 32 ohms! Thats a recipe to fry the output tranny fast! Something about flyback voltages aching inside the OT.

Generally speaking a mismatch of one in one direction or the other is OK ie:8 ohm amp with 16 ohm cab,8 ohm amp with 4 ohm cab but not more than that as in 4 ohm amp with 16 ohm cab etc.

Im sure someone will elaborate but dont try it in the meantime. Bob
 

mprvise

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6,404
I've never even heard of a 32 ohm cab - do people really do this?

I try to play it safe and always match the cab to the output from the amp. Having several cabs that are wired differently has produced some brief accicental mismatches when swapping things around - no blown amps yet thank goodness!
 

HKGuns

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92
I'm pretty sure you can drive a higher ohm load speaker with a lower amp out. i.e. You can drive a 32 ohm speaker with an 8 ohm amp out, but it will not be as loud. You cannot (and should not) drive a 4 ohm speaker with a 16 ohm amp output.

That being said, you should try to match impedences. So the best thing would be 2-16 ohm wired for 8 ohm load.
Not to be argumentative, but this is not the case. 8 ohm OT to a 16 Ohm cabinet is OK as long as you have a strong OT. As the poster above said, one mismatch in either direction is "usually" OK.

As I stated. Wiring an 8 ohm OT to a 32 ohm cabinet is a quick way to fry an OT.

A mis-match is a mis-match, the direction of the mis-match doesn't matter.
 

rockon1

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Not to be argumentative, but this is not the case. 8 ohm OT to a 16 Ohm cabinet is OK as long as you have a strong OT. As the poster above said, one mismatch in either direction is "usually" OK.

As I stated. Wiring an 8 ohm OT to a 32 ohm cabinet is a quick way to fry an OT.
Absolutely.


A mis-match is a mis-match, the direction of the mis-match doesn't matter.

Thats not my understanding. While a cab ith a higher impedance than the amp may put the OT in harms way from flyback voltages its safer to run a cab with lower impedance than the amp(ie;4 ohm cab with 8 ohm amp) . It actually puts less stress on the output transformer and more on the power tubes. Bob
 

suhr_rodney

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1,072
Parallel means lower inductance, brighter tone.
It's been a long time since my EE classes and theory doesn't always teach practicality. The current is greater in series, certainly, and that lowers inductance (assuming magnetic flux is constant). It makes sense that could affect the tone. Never thought of it, frankly. Interesting post!
 

rockon1

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12,465
As far as series vs parallel. I find series to be slightly looser and slightly edgier/complex sounding. Parallel seems more dampened and slightly less complex/bright.
 

mmorse

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961
Absolutely.





Thats not my understanding. While a cab ith a higher impedance than the amp may put the OT in harms way from flyback voltages its safer to run a cab with lower impedance than the amp(ie;4 ohm cab with 8 ohm amp) . It actually puts less stress on the output transformer and more on the power tubes. Bob
I saw a video some time back of Greg Germino demoing one of his amps with a couple of 412 cabs each with different speakers. He played through one cab and then the other. He played through each cab with the impedance matched and then once each with a mismatch in each direction. In other words, the cabs were 8 ohms and he played the amp at 4, 8 and 16 ohms. His point was that you could get tonal variations by impedance mismatching. The implication was that you could go one step in either direction.
 

rockon1

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12,465
I saw a video some time back of Greg Germino demoing one of his amps with a couple of 412 cabs each with different speakers. He played through one cab and then the other. He played through each cab with the impedance matched and then once each with a mismatch in each direction. In other words, the cabs were 8 ohms and he played the amp at 4, 8 and 16 ohms. His point was that you could get tonal variations by impedance mismatching. The implication was that you could go one step in either direction.

Generally speaking -yes.
 

rockon1

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12,465
No problem, I always match things up. In home systems you can drive 8 or 16 ohm speakers with 2 or 4 ohm output amps with no problem. However, you cannot drive 4 ohm speakers with higher ohm amps unless you want to buy another amp. Maybe it's different with Guitar tube amps.
Solid state and tubes react differently to load changes. Its always safe to run higher impedance loads with a SS amp. However power output is greatly reduced. If you go below the minimum rating for a SS amp it will fry.
 




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