Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

micro subwoofer a-la velodyne microvee
micro subwoofer a-la velodyne microvee
Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 28th July 2017, 02:27 PM   #1
robinlawrie is offline robinlawrie  United Kingdom
diyAudio Member
 
Join Date: Feb 2008
Default micro subwoofer a-la velodyne microvee

im running some calculations on a possible mocro subwoofer using the tangband W6-2100 6.5 inch subwoofer

Tang Band W6-2100 6-1/2" RBM Flat Panel Subwoofer 4 Ohm



and a pair of 6.5 inch passive radiators in a 10- 15 litre box. the box would be barely bigger than the driver surrounds.. so.. really, really small.

its my first time working with passive radiators (theoretically at this point)

i was looking at the nice cheap dayton audio 6.5 inch jobbies here:

Dayton Audio SD175-PR 6-1/2" Passive Radiator

their excursion is a tad low (9mm vs 10 mm for the tang band) but there will be two of them so acceptable i think.


anyway, being a bit of a (total) noob in the theoretical side of speaker design, im a bit lost in winisd.

ive input the driver parameters, and simulated a vented enclosure in a 15 litre box. with a tuning frequency of 26 hz, for starters. the response curve looks great for such a small box. , down only 3db at 30 hz, and 10db at 20hz.

using the effective diameter of two of the passive radiators, i get a vent 18.1cm diameter and 734 cm long

however, the air mass ( and hence PR mass ) is a feeble 17 grams.

given the starting mass of the pair of PR's is 75 grams, working backwards, the equivalent vent would be 3.3 metres long, and the box would be tuned to circa 15 hz.

obviously this is useless. i may as well not bother with the PR's

making the box larger seems to make this even worse.

bringing the box right down to 5 litres, i get a more massive vent and therefore a heavier PR, but a) its impossible to make a box that small for these cones, and b) the freq resp. graph looks horrible, and worse than a single driver in a 10 litre sealed box.

what am i missing? where on earth do i find a pair of 6.5 inch passive radiators that only weigh 8.5 grams each ?!

considering eminence sell a passive radiator at 8 inches and a few hundred grams in weight, it seems odd my design with a slightly smaller cone is calling for unobtanium light PR's

its very likely i have just entirely messed up the calculation process... ?


on a related note, in winisd i get no SPL curve (says i need to input the spl of the speaker? its not supplied for the tang band speakers..)

i also cannot find a cone excursion graph, which seems quite a critical thing to check..


any brainpower you lot can lend me would be most appreciated as always.

i need a miniscule sub as the other half doesnt want more boxes in the room, and im only trying to add a bit of grunt and take the load off my modest mission 780'se's running on a gainclone amp i built. i figure a pair of these might be just the ticket if i can figure out the maths.


alternatively, should i just stick a pair of these drivers in small sealed boxes and eq the heck out of them? they have reasonable excursion and the curves are not bad even in a 10 litre enclosure. id need to add 5-6db at 30 hz and 3db at 20hz to match the PR's. not that id go that low really.

it would certainly be a simpler build.
  Reply With Quote
Old 28th July 2017, 05:50 PM   #2
Crashpc is offline Crashpc  Czech Republic
diyAudio Member
 
Join Date: Nov 2008
Hey. I think that counting with equivalent bassreflex port is not good way. In new WinISD, you cenrtainly have the choice of passive radiator, so you donīt have to rely on bassreflex estimations. Try that one, and maybe it will end up better....
  Reply With Quote
Old 28th July 2017, 06:06 PM   #3
chris661 is offline chris661  United Kingdom
diyAudio Member
 
chris661's Avatar
 
Join Date: Feb 2008
Location: Sheffield
You're missing a factor from your calculation - the passive radiator surround has it's own set of parameters. You can't consider PR mass alone.

WinISD Alpha can simulate PR enclosures.
Last ones I did, I just measured the impedance curve and played with mass until I was happy.

Chris
  Reply With Quote
Old 28th July 2017, 06:27 PM   #4
robinlawrie is offline robinlawrie  United Kingdom
diyAudio Member
 
Join Date: Feb 2008
thanks for the pointer! the passive radiator setting in winiso pro seems to give a massively different result. Unfortunately the hard drop off in gain is offputting! goes from -4db at 40 hz down to -15 at 30.

are there any rules-of-thumb as to how much mass you can load on a PR ?

i assume heavier loading places more demands on the woofer?

ive also discovered i can use a linkwitz transform (which admittedly i know almost nothing about) to try and approach the performance of the PR using a sealed box. its very interesting to see the massive amounts of cone excursion generated by this method... im just randomly changing parameters at the moment to see what i can get while keeping under the xmax of the driver.

if anyone knows of a 6.5 inch driver with 3cm of cone travel ill be sorted!

seriously though, any amazing , cheap 6.5 inch sub cones out there which might be suitable for such a project, ive not heard of? since the last time i used tangband their prices have tripled...
  Reply With Quote
Old 28th July 2017, 07:08 PM   #5
troystg is offline troystg  United States
diyAudio Member
 
troystg's Avatar
 
Join Date: Apr 2004
Location: In a dream, Please don't wake me...
Quote:
Originally Posted by robinlawrie View Post
........
if anyone knows of a 6.5 inch driver with 3cm of cone travel ill be sorted!

seriously though, any amazing , cheap 6.5 inch sub cones out there which might be suitable for such a project, ive not heard of? since the last time i used tangband their prices have tripled...


Anarchy Woofer DIY Sound Group
__________________
Troy
Thinking positive doesn't make things better, it makes you a better person.
  Reply With Quote
Old 28th July 2017, 07:18 PM   #6
wolf_teeth is offline wolf_teeth  United States
diyAudio Member
 
wolf_teeth's Avatar
 
Join Date: Mar 2006
Location: Indiana
My Triumph subwoofer uses the W5-1138 and a pair of Peerless PRs in a 9" cube. Will that work?
Wolf
__________________
Photobucket picture pages: http://photobucket.com/Wolf-Speakers_and_more
Writeups/thoughts/blogs: http://techtalk.parts-express.com/blog.php?u=4102
  Reply With Quote
Old 28th July 2017, 07:30 PM   #7
robinlawrie is offline robinlawrie  United Kingdom
diyAudio Member
 
Join Date: Feb 2008
That anarchy woofer looks awesome. 25mm xmax?! biggest question is.. can i get it in Europe?


-wolf.. do you have any further info on your sub? sounds similar to my idea...
  Reply With Quote
Old 28th July 2017, 07:33 PM   #8
robinlawrie is offline robinlawrie  United Kingdom
diyAudio Member
 
Join Date: Feb 2008
ah.. ive just noticed the xmax is actually "only" 12mm.. the "peak to peak" is 25mm..

so, basically the same as the tang band w6-1139 (13mm xmax)
  Reply With Quote
Old 28th July 2017, 09:47 PM   #9
robinlawrie is offline robinlawrie  United Kingdom
diyAudio Member
 
Join Date: Feb 2008
im trying to enter the parameters of the anarchy driver into the winisd pro alpha, but every time i hit save it says there are errors with loads of the parameters, and that i should consult the (nonexistant) help.

i get the same result when i try and enter the specs of another tangband sub.

alpha version problem? bit limiting if i can only use the provided speaker profiles.
  Reply With Quote
Old 28th July 2017, 09:54 PM   #10
Crashpc is offline Crashpc  Czech Republic
diyAudio Member
 
Join Date: Nov 2008
Dunno. If you add some parameters, let the other get counted, instead of hand writing it. If you have Qes and Qms, let Qts alone. It will count itself. The same works for Vas, Mms and Sd....
  Reply With Quote

Reply


micro subwoofer a-la velodyne microveeHide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Velodyne MicroVee 1000 rms Class-D Amplifier Humming Problem Soundfreak87 Class D 23 1st August 2019 02:09 AM
Velodyne MicroVee Subwoofer Plate Amplifier dudaindc Swap Meet 2 1st May 2016 10:51 AM
FS: Velodyne subwoofer amps... Stuart Easson Swap Meet 19 3rd March 2014 01:17 PM
Velodyne subwoofer Bablo Subwoofers 0 12th February 2013 02:20 AM


New To Site? Need Help?

All times are GMT. The time now is 02:09 AM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 14.29%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Copyright ©1999-2019 diyAudio
Wiki