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Discussion Starter #1 (Edited)
diy sub for my bro - big update**

Hi All,

Just modeled three subs, all 30litre box with a 3db gain at 38hz.

Thing is the tang band 8" is modelling very well. Just from looking at the grpahs it looks the best to me, how can this be the case when compared with the adire dpl12 or the mivoc aw 3000? Or am i looking at the wrong things.... I suppose the question is with a 30 litre limit what would be the driver of choice? (80 watt amp, 3db gain at 38hz - 30hz rumble filter)

Tang band w8-740 is pink line (30litre tuned to 28hz, port is 3"x20")
Mivoc aw 3000 is grey line (30 litre tuned to 26hx, port is 3"x23")
Adire DPL 12 is yellow line (sealed 30 litre - box fsc is 47hz)





 

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Elite Shackster
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Re: 3 subs, winisd critique if you can spare a moment.

Well for one thing anytime you port a box you will gain a flatter response and higher spl to tuning compared to a sealed enclosure. Also, the enclosure for the Adire is too small for a home theater application, giving you a Qtc of .945. Ideally this number should be somewhere around .7. Having a higher Q raises the sensitivity to higher frequencies and lowers sensitivity to lower frequencies as can be seen by your modeling. With enough power this can be overcome with eq, but it isn't ideal.

Personally, I'd try to see how the Adire models in a vented box and go from there. If you're limited to only 80 watts of power you'll want the extra output.
 

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Re: 3 subs, winisd critique if you can spare a moment.

Tangbands response is peaking at the tuning freq., looks like it is tuned lower than ideal.

Mivoc's response starts to fall sharply below 40hz, which suggests that the Mivoc is designed for a space with a strong boundary gain(eg. car's interior).

Adire's response is quite good, although it is in a smaller than ideal enclosure.

I'd definetly go with the Adire, first of all because of the good response, secondly because of the spimlicity of the build. As you reduce the volume of the enclosure, you have to use longer vents to get the desired tuning frequency. In this case you'll have to use >20" vents, which will further reduce the effective volume. A 3" 50cm(~20") vent will take up 6l, which means your 30l enclosure will become a 24l enclosure.

Anyways, it's your choice. If the 30l volume is strict, your best bet might be Adire. If you can go a little bigger, the Mivoc might work out better. You just have to remember that some car audio brands tend to exaggerate their driver's T/S parameters, which will make the driver look better, and simulations inconclusive. For example a common "mistake" is misspelling the inductance value(eg. 2.5mh -> 0.25mh). Also some car audio manufacturers market the mechanical excursion limits of the driver as it's xmax, instead of the normal point where BL is down 30%.
 

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Discussion Starter #4 (Edited)
Re: 3 subs, winisd critique if you can spare a moment.

i just modelled the adire with a 3"x15" port and it does now start to look to be the clear leader in terms of spl etc. I only modelled it sealed as that is what winisd suggested (newb alert)

tbh though for the ease of build the sealed box still looks good

here is the transfer function magnitude graph - adire with port is purple
 

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Elite Shackster
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Re: 3 subs, winisd critique if you can spare a moment.

Yikes! That's gong to be a tough sub to implement in a home theater. You want the flattest overall response for best sound. If you are limited to those three drivers and only 80 watts, I'd recommend the Adire in a sealed config or the TB 8". In all cases here you are amp limited, not driver limited.
 

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Discussion Starter #6
Re: 3 subs, winisd critique if you can spare a moment.

Yikes! That's gong to be a tough sub to implement in a home theater. You want the flattest overall response for best sound. If you are limited to those three drivers and only 80 watts, I'd recommend the Adire in a sealed config or the TB 8". In all cases here you are amp limited, not driver limited.
doh! dpl12 is 4 ohm so amp power is 150watt. I agree though, the dpl12 in a 30litre sealed is going to be the way to go.
 

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Re: 3 subs, winisd critique if you can spare a moment.

I remember when Raw Acoustics was making HT subs with the Tang Band W8-740C. The cube was 14 inches measured externally, it was built out of 3/4 inch MDF, and porting was two 2 inch ports 16 inches long. The ports used 45 degree elbows to make the length fit internally. It performed well in a small room.
 

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Discussion Starter #8
Re: 3 subs, winisd critique if you can spare a moment.

I remember when Raw Acoustics was making HT subs with the Tang Band W8-740C. The cube was 14 inches measured externally, it was built out of 3/4 inch MDF, and porting was two 2 inch ports 16 inches long. The ports used 45 degree elbows to make the length fit internally. It performed well in a small room.
I think the deal is done now on the dpl12's - the tang band does seem to model very nicely with 25litres, tuned to 30hz. Strange considering the dpl12 has over 5 times the vas and double the sd. Surely the dpl12 will blow the little 8 away in the real world.
 

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Re: 3 subs, winisd critique if you can spare a moment.

There's no replacement for displacement :) Vas (equivalent volume) isn't related to the amout of air displaced by the sub, but both Vd (Sd*Xmax) and Sd (cone surface area) are. Looking forward to your build thread, if you are going to make one, that is :T
 

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Discussion Starter #10 (Edited)
Re: 3 subs, winisd critique if you can spare a moment.

There's no replacement for displacement :) Vas (equivalent volume) isn't related to the amout of air displaced by the sub, but both Vd (Sd*Xmax) and Sd (cone surface area) are. Looking forward to your build thread, if you are going to make one, that is :T
lol I know, I had 2 different tang band subs on the way b ut they never arrived so got a refund. Now I have 2 x plate amps waiting for a build so need to buy something. I have at least 2 dpl12's coming maybe 4.. don't have the space for diploe though. One sub is for my brother in law the other is for my lounge. There will be a build...
 

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Re: 3 subs, winisd critique if you can spare a moment.

don't even go there.. i was part way through a build and my wife nearly devorced me!
Ouch! So IB is out of count. If you order 4 drivers, and one goes to your brother in law, that leaves you with 3 drivers. You could build active bass modules for your mains if you had 2 more amps. If you go with one driver, I'd definetly go with the 30l box. A vented box would inevitably be larger because of the volume the vent takes up.
 

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Discussion Starter #16
Re: 3 subs, winisd critique if you can spare a moment.

I assume you found the Adire DPL12 second hand somewhere?
yes Mike - on another forum, the chap has 4 of them. I am buying all4 to make his sale easy - I only need two.

He is selling them for 20 euro's each so they seem like a bargain really.

I don't have the room in my house for active mains.. I am trying to get some full range drivers to make some speakers but even they are limited to about 5 litres.
 

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Discussion Starter #17
Re: 3 subs, winisd critique if you can spare a moment.

:bigsmile: I now have 2 x adire dpl12's in my posession, along with the mivoc am 80 and some 18mm MDF. Hopefully start making sawdust tomorrow..

one more question though,., the dpl 12 has dual 6.8 ohm voice coils when i wire then in paralell they run at 3.6 using a multimeter. Will my mivoc be ok with this? it is only rated to handle a 4 or 8 ohm load.
 

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Discussion Starter #19
Re: 3 subs, winisd critique if you can spare a moment.

Congrats! Will you be posting pics?

What is the model of your amp? Are you going to be running both subs off of the amp?
I will be posting pics. only using one driver per sub, first sub is using a mivoc am80.
 
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