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Voice Kraft 12" inch
Voice Kraft 12" inch
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Old 12th July 2018, 06:03 PM   #1
Evergarden is offline Evergarden  Lithuania
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Default Voice Kraft 12" inch

Hello,

I'm working on a box for Voice Kraft GDN 30/80 12" inch subwoofer. Parameters: Fs 25 Hz / Qms 2.47 / Qes 0.3 / Qts 0.26 / Vas 270 liters / Bl 13 Tm / Mms 50g / Cms 0.000819 m/N / RMS 80W.

Trying to make 6th order bandpass:

1) 75 liters @ 29hz with 90 sq.cm port 34 cm lenght and 30 liters @ 76 Hz 120 sq.cm port 13 cm lenght.
2) 90 liters @ 29hz with 90 sq.cm port 28 cm lenght and 35 liters @ 72 Hz 120 sq.cm port 11 cm lenght.

However i'm not sure how 6th order bandpass is going to sound. So as alternative Bass reflex box is also a good option:

1) 75 liters @ 37 Hz with 90 sq.port 19 cm lenght.
2) 100 liters @ 35 Hz with 90 sq.port 15 cm lenght.

I would like to get some help and knowledge which box should I use and what should I change to make them better.
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File Type: jpg 7530_2970.jpg (130.4 KB, 196 views)
File Type: jpg 9035_2972.jpg (129.6 KB, 189 views)
File Type: jpg 75_100.jpg (134.1 KB, 192 views)

Last edited by Evergarden; 12th July 2018 at 06:42 PM.
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Old 13th July 2018, 09:44 AM   #2
chris661 is online now chris661  United Kingdom
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What are you trying to achieve with this subwoofer?

Chris
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Old 13th July 2018, 01:25 PM   #3
Evergarden is offline Evergarden  Lithuania
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I have to start with the fact that this is my first subwoofer. My knowledge about audio system and 6th bandpass/vented box is at best minimal. I want to make the best out of this subwoofers and get as much as possible deep and loud bass. That's why Fb @ 29Hz.
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Old 14th July 2018, 12:15 AM   #4
GM is offline GM  United States
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Greets!

Best overall performing 6th order will be either a tapped TL [TTL] or horn [TH], but need the rest of the specs to input into Hornresp: Sd, Re, Le @ 1 kHz, Pmax, Xmax

GM
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Last edited by GM; 14th July 2018 at 12:18 AM.
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Old 14th July 2018, 06:45 AM   #5
Evergarden is offline Evergarden  Lithuania
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Greets!

Best overall performing 6th order will be either a tapped TL [TTL] or horn [TH], but need the rest of the specs to input into Hornresp: Sd, Re, Le @ 1 kHz, Pmax, Xmax

GM

I have to start with the fact that this is my first subwoofer project. My knowledge about audio system and 6th bandpass/vented box is at best minimal. I want to make the best out of this subwoofer and get as much as possible deep and loud bass. I know that this subwoofer is not suitable or the best one to use at home. However I can't find anything better in my country Lithuania. If there is a better choice at 30-40 euros price tag I would like to know. I could try to find them in Ebay or Amazon (or any shop that ships to Lithuania).



Sd 500 sq.cm / Re 6.2 ohms / Le (not provided). However I have Flux density 0.7 T / Energy in air gap 388 mJ / Voice coil height 12.5 mm / RMS 80 Pmax 140 / Xmax (not provided)
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Old 15th July 2018, 05:04 PM   #6
GM is offline GM  United States
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It's not bad, basically vintage prosound specs, so just needs to be relatively very large to huge by today's standards to go low due to its very compliant suspension [high Vas]. Note that Vas becomes ~292 L based on Sd, Cms.

I don't keep up with component availability, but 40 euros [$46.75 USD] certainly wouldn't get me anywhere near this 'strong' a motor in the USA in a 12" woofer AFAIK, so have to wonder if these specs are anywhere near accurate.

If they are, then to go down to 20 Hz at highest practical peak SPL assuming a typical low power 12" ~6 mm Xmax will require ~560 L net and even then only generating > ~105 dB/20 Hz/m - ~115 dB/80 Hz/m XO point before any room gain is factored in, so cheap driver at the expense of a small closet sized, relatively expensive cab to make.

25 Hz = ~437 L net > ~108 dB/24 Hz/m - ~116 dB/80 Hz/m XO point, so the better choice overall for music and most movies.

30 Hz = ~366 L net > ~112 dB/30 Hz/m - ~118 dB/80 Hz/m XO point.

Stuck in a corner or at least laying on the floor up against a wall should generate some respectable SPLs though, especially if in a small room.

If these are too big and/or expensive, then there's smaller pipe horn options, though of course at the expense of lower peak SPL capability.

GM
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Old 15th July 2018, 09:41 PM   #7
Evergarden is offline Evergarden  Lithuania
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It's not bad, basically vintage prosound specs, so just needs to be relatively very large to huge by today's standards to go low due to its very compliant suspension [high Vas]. Note that Vas becomes ~292 L based on Sd, Cms.

I don't keep up with component availability, but 40 euros [$46.75 USD] certainly wouldn't get me anywhere near this 'strong' a motor in the USA in a 12" woofer AFAIK, so have to wonder if these specs are anywhere near accurate.

If they are, then to go down to 20 Hz at highest practical peak SPL assuming a typical low power 12" ~6 mm Xmax will require ~560 L net and even then only generating > ~105 dB/20 Hz/m - ~115 dB/80 Hz/m XO point before any room gain is factored in, so cheap driver at the expense of a small closet sized, relatively expensive cab to make.

25 Hz = ~437 L net > ~108 dB/24 Hz/m - ~116 dB/80 Hz/m XO point, so the better choice overall for music and most movies.

30 Hz = ~366 L net > ~112 dB/30 Hz/m - ~118 dB/80 Hz/m XO point.

Stuck in a corner or at least laying on the floor up against a wall should generate some respectable SPLs though, especially if in a small room.

If these are too big and/or expensive, then there's smaller pipe horn options, though of course at the expense of lower peak SPL capability.

GM

It's both expensive and big. Considering that subwoofer is at 38 euros price tag. There is no point to spend ~30 euros on a materials for enclosure. How about the pipe horn?
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Old 17th July 2018, 05:11 PM   #8
GM is offline GM  United States
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Hmm, not familiar with your local economy, but if this large a cab is only ~38 euros each and constitutes 'expensive', then your 100 L/35 Hz BR may be best option as going down to Fs in the simplest pipe will be still larger.

Anyway, a lightly stuffed, inverse tapered tapped pipe tuned to 25 Hz and limited to ~105 dB/m using a 100 Hz/4th order XO is ~113 L net and an even easier to fold 30 Hz simple TL [straight pipe] > ~105 dB from ~27 Hz/m is ~140 L.

GM
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Old 17th July 2018, 07:07 PM   #9
Evergarden is offline Evergarden  Lithuania
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Hmm, not familiar with your local economy, but if this large a cab is only ~38 euros each and constitutes 'expensive', then your 100 L/35 Hz BR may be best option as going down to Fs in the simplest pipe will be still larger.

Anyway, a lightly stuffed, inverse tapered tapped pipe tuned to 25 Hz and limited to ~105 dB/m using a 100 Hz/4th order XO is ~113 L net and an even easier to fold 30 Hz simple TL [straight pipe] > ~105 dB from ~27 Hz/m is ~140 L.

GM

Probably you are right. I should stick with this option "25 Hz = ~437 L net > ~108 dB/24 Hz/m - ~116 dB/80 Hz/m XO point, so the better choice overall for music and most movies.". Can you help me with enclosure design, because I have no idea how to make one. I'm working on Hornresp, however i'm lacking experience.
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Old 19th July 2018, 01:44 AM   #10
GM is offline GM  United States
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For starters, attached is the HR file to download/install to get basic dimensions, etc.. The rest, only up to a point, I mean I can answer questions, but not set up to calculate any folding, though Brian has a program that will help if more than a single fold: The Subwoofer DIY Page - Horn Folding

GM
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