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Ohm-age

Daveypunk

Daveypunk

May 12, 2019
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0
#1
So I have a 8ohm 400w 1x15 Warwick cab, I run this with a 4ohm amp, it’s okay....

I’m planning on adding a 10inch 8ohm Midrange driver wired in parallel to increase output and gain more from the amp.

Is there anyway of adding a horn (similar to the SWR Triad) without messing the Ohm-age about? If so what rating would this and the Mid driver need to be?!

Cheers
 
#2
The word impedance isn't that complicated.

Mixing a 15 and a 10 at the same impedance isn't wise. They will receive the same power and your 15 will be limited by the 10, which may risk a short life. Another 15 or a 2x10 shall work better.

Provided a well adjusted filter, horns don't affect impedance.

The sticky at the top of the amp forum shall help you.
 
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#9
Daveypunk said:
So I have a 8ohm 400w 1x15 Warwick cab, I run this with a 4ohm amp, it’s okay....

I’m planning on adding a 10inch 8ohm Midrange driver wired in parallel to increase output and gain more from the amp.

Is there anyway of adding a horn (similar to the SWR Triad) without messing the Ohm-age about? If so what rating would this and the Mid driver need to be?!

Cheers
Click to expand...

I believe the SWR Triad had a problem with blowing up the 10" driver. In order to prevent this you should apply an HPF to the 10" so it doesn't exceed its mechanical power handling limit. While your at it, you might as well apply a complementary LPF to the 15" so you don't get a lot of destructive phase interference in the mids. In other words you probably need a crossover network between the 15" and 10".

Many bass speakers run the mid range without an LPF, but you will need an HPF to protect the horn. The HPF for the horn could be selected based upon the natural roll off of the mid driver. Or you could go ahead and put an LPF on the mid driver as well, so your system functions as a true 3-way design.

HPF and LPF sections modify the system impedance. In the filter's pass band, the impedance is low so the amp sees the nominal impedance of the driver. As the frequency approaches the cutoff of the filter, the impedance starts to rise. So when you have complementary LPF and HPF sections, one sections cuts off as the other starts passing signal. The idea is there is a smooth transition of impedance through the crossover region, and the amp sees the nominal impedance of the drivers within their pass bands, unless other means are taken to modify the impedance. For example some crossovers are designed for an 8 ohm woofer and 16 ohm horn drivers, but present an 8 ohm nominal impedance to the amp.
 
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#10
Daveypunk said:
So I have a 8ohm 400w 1x15 Warwick cab, I run this with a 4ohm amp, it’s okay....

I’m planning on adding a 10inch 8ohm Midrange driver wired in parallel to increase output and gain more from the amp.

Is there anyway of adding a horn (similar to the SWR Triad) without messing the Ohm-age about? If so what rating would this and the Mid driver need to be?!

Cheers
Click to expand...

Welcome to TalkBass!!!!

The topic of mixing driver sizes and different cab physics can spark some interesting debates around here.

Here's the short version.

Frequency response and volume has as much to do with cab physics as it does driver size. So you could actually build an 8" cab that will sound more "boomy" than your 15" cab.

Mixing driver sizes and cabs might sound amazing. But it might sound like warm garbage. Phase cancellation (I think) AMD several other terms play into it. The sticky up top has a lot of good reading on the subject.

Hope you get it all hammered out.
 
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#11
Daveypunk said:
So I have a 8ohm 400w 1x15 Warwick cab, I run this with a 4ohm amp, it’s okay....

I’m planning on adding a 10inch 8ohm Midrange driver wired in parallel to increase output and gain more from the amp.

Is there anyway of adding a horn (similar to the SWR Triad) without messing the Ohm-age about? If so what rating would this and the Mid driver need to be?!

Cheers
Click to expand...

You are essentially describing the engineering behind the infamous Ampeg SVT-1510HE cabinet. The brilliant minds at Ampeg back in the day thought it would be a good idea to run two very different drivers in parallel with a crossed-over horn. As one might expect, it's difficult to find one of these cabs that doesn't have a blown 10" driver in it.

Some advice: Ditch the 10" midrange driver idea. Either buy a second Warwick 15" cab, or start over with an adequate 3-way cab (if you're into bi-amping).
 
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#19
Wasnex said:
IMHO....all of you who continue to bust on the usage of "Ohm-age" need to develop a sense of levity :rollno:.
Click to expand...

But is it not also our responsibility as seasoned, knowledgable players to correct inaccurate terms when we see them and to teach where we can? The OP just joined our ranks on Sunday, welcome @Daveypunk, he now knows the correct term for what he is asking about. :)
 
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