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I have a Zapco ST-1350XM II amp for (2) IDQ 10 subs that I am going to buy. Is there any advantage or disadvantage in wiring for 1 ohm vs 2 ohm. Wanted some opinions before purchasing subs.
 

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I have a Zapco ST-1350XM II amp for (2) IDQ 10 subs that I am going to buy. Is there any advantage or disadvantage in wiring for 1 ohm vs 2 ohm. Wanted some opinions before purchasing subs.
Some subwoofers behave differently in their dual 2 ohm versions vs their dual 4 ohm versions because they have slightly different ts perimeters. Take for example the AudioFrog GB12 subwoofers I recently purchased. At the time the dual 4 ohm version was backordered but when I modeled them in Bassbox pro I noticed that the GB12 D2 was louder on less power and had a slightly different curve. This also shows up in the AudioFrog frequency charts on their website in the ported configuration. The D2 has a higher sensitivity rating but also has slightly less XMAX. If you live in a hot climate and or the amplifiers you have are in a tight space it might make more sense to go with a higher expedience configuration because the amplifier would generate less heat. In the past using 1 ohm final loads was all the rage because amplifier power was expensive and you could get more power with a 1 ohm final load but today amplifier power is cheap so now you can go with a larger amplifier that is more efficient and produces less heat and it doesn't cost a ton of money to do that now.
 

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Three of those 7 posts disagreed with one another, "lower ohms make the amp work harder", "higher ohm load makes it work harder" another said it didn't matter. Posts were all over the place.
 

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Being from the Phoenix area where we have 4-5 months of 100°+ weather I guess I could do the amp a favor and just run at 2 ohms. Having 400-450 watts available to each sub should be sufficient.
 

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Three of those 7 posts disagreed with one another, "lower ohms make the amp work harder", "higher ohm load makes it work harder" another said it didn't matter. Posts were all over the place.
Heat is the enemy of electronics and a lower ohm load will make the amplifier flow more current which is harder on the mosfets and electronics even when its designed for it. Higher ohm loads have never been known to hurt an amplifier even if its harder for them to push more current through and so they just flow less amperage, which in the end does not hurt the amplifier.
 

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Thanks for the replies. I found a test of that amp and even though it was a refurbed unit it did not perform to advertised ratings, but even if it is only 400W per sub that should be fine for my build. I will order a couple of 2 ohm DVC subs next week.
 

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I have a Zapco ST-1350XM II amp for (2) IDQ 10 subs that I am going to buy. Is there any advantage or disadvantage in wiring for 1 ohm vs 2 ohm. Wanted some opinions before purchasing subs.
Check out Ryan Blankenship's amp dyno on youtube of that exact amp. He dyno'd a refurbished amp that didn't quite measure up. He later dyno'd a brand new 1350xm and said the same mosfets blew at 1 ohm. I thought the dyno of the refub amp was a fluke but since the same exact thing happened to the new amp it would deter me of running those amps at 1 ohm.
 

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I'm running the ST-1000 @ 2 ohm for two GB12s and it's PLENTY of power.
 

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Some subwoofers behave differently in their dual 2 ohm versions vs their dual 4 ohm versions because they have slightly different ts perimeters. Take for example the AudioFrog GB12 subwoofers I recently purchased. At the time the dual 4 ohm version was backordered but when I modeled them in Bassbox pro I noticed that the GB12 D2 was louder on less power and had a slightly different curve. This also shows up in the AudioFrog frequency charts on their website in the ported configuration. The D2 has a higher sensitivity rating but also has slightly less XMAX. If you live in a hot climate and or the amplifiers you have are in a tight space it might make more sense to go with a higher expedience configuration because the amplifier would generate less heat. In the past using 1 ohm final loads was all the rage because amplifier power was expensive and you could get more power with a 1 ohm final load but today amplifier power is cheap so now you can go with a larger amplifier that is more efficient and produces less heat and it doesn't cost a ton of money to do that now.
Sorry to be late...but some good info in there mate...appreciated!

Sorry to 'hijack' the thread gonzo...but JC's statement made me think of the potential for differing responses if running a DVC sub at 1 or 2 ohm...? I am considering something similar and had not thought about any effect on the model...

With that said I am rusty as hell on car audio due to <life> having drawn me away...so I may have just asked a stupid question...I can't remember if ts parameters for a DVC sub change if the coils are parallel or series and whether or not that effects the enclosure design...I don't even think I have BB installed anymore :eek:

My apologies but I also had to comment on that link. It did not make any sense and did not answer the OP's question...props JC for putting it back on track.

Peace
 

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I’m no expert in Thiele & Small Parameters so don’t hold me to anything below. I just cut and paste the AudioFrog GBD2 vs D4 perimeters below for comparison sake. I’m guessing the major differences are in the voice coils themselves where the D2 has a shorter and lighter voice coil and the D4 has a longer and heavier voice coil although the Mmd says otherwise. This also explains why the D2 has slightly less XMAX with the shorter voice coil. If the voice coil and weight are less on a speaker than the sensitivity should go up and you sacrifice some bandwidth as a trade off. The D2 wired at 1 ohm has a sensitivity of 95 db at 2.83 volts/1meter and the D4 is 92 db wired at 2 ohms. The inductance is also greater on the D4 and again I’m guessing due to having a longer voice coil. Also attached is a picture of the model in BB showing the predicted response based on these ts parameters. Some things to note are that not all companies share these differences between D2 and D4 drivers of the same models and a lot of them only post the series parameters or the ones that look best to the misinformed so it can be difficult to get good information.

Thiele & Small Parameters:

Revc: 1 Ω or 4Ω
[email protected]: 0.33 mH (2 Ω configuration)
Mmd: 183 g
Mms: 189 g
Cms: 153 µM/N
Vas: 57 liters
Fs: 29.5 Hz
BL: 8.37 TM (1Ω configuration)
Qms: 8.44
Qes: 0.52
Qts: 0.49
Xmax (1-way linear): 17.6 mm (11/16”)
Basket Displacement: 4.17 liters (0.147 ft3)

Thiele & Small Parameters:

Revc: 2 Ω or 8Ω
[email protected]: 0.58 mH (1 Ω configuration)
Sd: 510.7 cm2
Mmd: 177 g
Mms: 184 g
Cms: 171 µM/N
Vas: 63.7 liters
Fs: 28.4 Hz
BL: 11.47 TM (1Ω configuration)
Qms: 8.82
Qes: 0.52
Qts: 0.49
Xmax (1-way linear): 19 mm (11/16”)
Basket Displacement: 4.17 liters (0.147 ft3)

In the picture of the graph the D4 subwoofer has a slight advantage below 48 Hz but above that the D2 is louder by a significant amount with less power.
 

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Three of those 7 posts disagreed with one another, "lower ohms make the amp work harder", "higher ohm load makes it work harder" another said it didn't matter. Posts were all over the place.
Both are correct, they are speaking from different perspectives... allow me to maybe shed a little light...

Lower ohms make the amp work harder... well the amp will draw more current, dissipate a little more energy as heat... so technically it’s working harder... but for a given power out (eg 1ohm 1500watt vs 2ohm 800watt on the same amp for example) at a given power (say 500watts) the 1ohm load will have slightly less distortion as it’s further away from clip...

Higher ohms make the amp work harder... well at higher ohm loads for a given power the amp will be working nearer to its rail voltage and therefore nearer to clipping and also be slightly less efficient, plus distortion will generally be slightly higher

So both are correct kind of...

For a certain amp, if it’s stable to a lower load I’d always run it at the lowest impedance as for a given listening level requiring x power the lower load will always be further away from clipping and therefore have less distortion unless it’s a really crappy amplifier who power supply and output section struggles to deliver the current/power it requires 👍🏼
 

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Your electrical system and your amp would be happier at 2 ohms, long term, all else equal. And remember, it takes 2x the power to achieve just a 3 db gain. You probably won't notice a lot of difference with the extra power at 1 ohm compared to 2, IMO.
 

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...I can't remember if ts parameters for a DVC sub change if the coils are parallel or series and whether or not that effects the enclosure design..
Some of the parameters change, but it all leads to the same box for the same sub. Bl changes, Re changes, Le changes, some others change, Bl^2/Re remains the same. Same sub, same box, no matter how it's wired, as long as you still use both coils.
 
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