There are many great subwoofer projects scattered all over the AVSForum as well as the internet. It would be useful to have an index, which is the objective of this thread. Just point to your favorite subwoofer details page and then I will add it to the index. We can figure out how to organize it once we have a nice big list.
12" Peerless XLS dual passive radiator sub project (passive radiator) by Adrian Mack
12" THT is alive! (12", horn) by moab_dan
13.8cubic foot, mach5 IXL18.2.2 build (ported, 18") by N8DOGG
15" TC sound LMS curved box build (sealed, 15", aesthetic, *hall of fame*) by ClintonH
18” down-firing EGG shaped sub build (sealed, 18", aesthetic) by Gmichael2
2 Wolfhorn SDX’s as a riser (horn) by FUN4ME
21" Maelstrom Curved Box Build (sealed, aesthetic) by corock
36" THT^Cube (horn) by dykz34
3.75 cu.ft. sealed sdx15 w/ oaudio 500w plate amp (15" sealed) by RodK
$700 playhouse sub (ported, FI Q18") by scpete26
8x 18" LMS Ultra 5400s in 4 sealed enclosures (sealed, *hall of fame*) by notnyt
8x 18" LMS 5400 Ultras Sealed to 27 Cube 15hz Ported Build (ported, *hall of fame*) by notnyt
Air Supply's DUAL THT/Small Room Build (horn) by Air Supply
Almighty Subwoofers (ported, 15", pro-audio drivers) by Stig Erik Tangen
Altec 18" in 4m long transmission line (transmission line) by Jack Bouska
Bedlam in Goliath: RE Audio XXX18 subwoofer build (ported, 18", *hall of fame*) by Ricci
Bon Voyage! My first DIY subwoofer (sealed, 12") by Danielson99
Building subwoofer using 18LW1400 driver in vented box (slot ported, 21", pro-audio driver) by DL86
Beer Fridge, Sidewinder, Blast Furnace, Snorky, Infinite Baffle, etc. (several projects) by Collo
The BlackReign: 2x21" sealed sub (dual 21" sealed) by scomed99
The Bonecrusher (dual 15" w/quad passive radiators by rightbrained
Canadian_Dude's CSS SDX15 with 2 CSS PR1816 passives (passive radiator) by Canadian_Dude
Collaborative Tapped horn project (tapped horn) by paulspencer
CSS Quartet12 (TRIO12) H in 24" Cube (passive radiator) by caper_1
CSS TRIO12 Front Loaded subwoofer 16hz F3 (horn) by mwmkravchenko
Danley DTS-10 "Super Spud" DIY kit (low-tuned tapped horn) by Tom Danley
Dave's THT Build Thread (horn) by Dave (DL86)
Dave's Quad 18" Fi IB (infinite baffle) by Avus_M3
Dayton 12" 1.2 cu ft (sealed) by Ken Cline
Dayton RS sub project: Assault on SQ (quad 15", sealed, aesthetic) by engr_dave
DIY HiVi SP10 Subwoofer Project (10" ported) by Adam McCall
DIY Duel Front Firing Peerless Sub (sealed, dual 12") by Trofius
Dragonslayr's THT Build (horn) by dragonslayr
DS1200 & DS1500 (sealed and vented, 4 plans) by Rythmik Audio
Dual 15" "Mofo" build (dual sealed) by Jay1
Dual 18" Sub Project (MK II) (dual, ported, 18") by Sam aka s_carter
Dual GR SW-12-08 + Rythmik A370PEQ Servo Sub (sealed, dual 12", aesthetic) by Stereodude
Dual Opposed AV15H Subwoofer Build (sealed, 15") by pdc
Dual opposed sealed JBL GTI MKI 15" sub build (dual 15", sealed) spanish68
Easy Button End Tables 24" x 21" x 36" (slot ported, 18") by NEO Dan
Easy Button End Table MAX 26.5" x 24" x 37.5" (slot ported, 18") by NEO Dan
Ebony and Ivory, dual 18" LMS-5400 Endtables (sealed, aesthetic) by jpmst3
Ezcl's Sub (sealed, 3x12") by Ezcl
eD custom built sub enclosure - TC Sounds 15" LMS-5400 (sealed) by shadowofnight
Ed 16Ov.2 - SF6 = Sealed Box Sub by MegaFlop
Ed 18-inch Sono's (began as 4 ported sonotubes, now 8 sealed sonotubes) by MKtheater
Eric's DIY 12" Subwoofer (short sonotube, ported) by Eric
First Look - TD-18H+ by Tack
Four 18" LMS-5400's (4x18" w/eight passive radiators, aesthetic, *hall of fame*) by robertcharles
Funky Waves 18” LMS 5400 + 2 PR build by lukeamdman
Gjallerhorn (18" LMS tapped horn, *hall of fame*) by Ricci [build details begin on page 11, post #304]
High output 8" Tapped horn (8" tapped horn) by tsloms
Home-Made Home Theater Subwoofer (sealed, 12") by Matt
Infinite Baffle Subwoofer (4x15") by Jonathan Foulkes
Is this wood any good? by javygonx
IXL 18 meets the "Easy Button" (ported, 18") by NEO Dan
Jai's LMS-5400/Passive Radiator design (passive radiator, 18") by jmcomp124
Jason's DIY Subwoofer (Rythmik Audio DS12 kit, sealed, 12") by Jason
JL Audio Enclosures Suggestions for Each Driver
(click on the driver, then scroll down to "Click Here For Recommended Enclosure Specifications")
13W7 Enclosure Specifications by JL Audio
Joining the THT club (dual horns, hall of fame documentation) by notnyt
Karl's Sub Project (sealed, 10") by Karl
LAB Subwoofer Project (horn, *hall of fame (technical)*) by Tom Danley
" http://www.prosoundweb.com/article/lsp_documentation_page_drawings_photos_specs_and_more/ "
(you have to cut and paste the link for this one)
Large.. Dual 15" RL-p Unit(ported, aesthetic) by steve nn
Lilmike's Cinema F-20 (horn) by lilmike
Lilmike's Cinema T-6 (horn) by lilmike
LMS 5400 Ultra X2 Build (18" sealed) by RDKing2
Lord of the Bass: The Two Towers(ported, sonotube, 2x18") by ssabripo
Lord of the Bass: Return of quad Sealed King (sealed, 4x18") by ssabripo
Maelstrom-X PR build...my first DIY by vili
Master SUB Woofer with ETON 12/680/60 HEX (sealed, 12") by Doede Douma
MAW-10 DIY Ported Subwoofer (ported, 10", $110) by Giovanni Militano
MBM - 2 x JBL 2226H by Myggpower
Meet MadMAX (HUGE horn) designed by Maxmercy, built by MX48 aka Moto
MFW-15 Project Advice Needed (15" sealed) by Scott C
My first TC SOUNDS DIY sub! by maintrain
Myn's Tuba HT Build Thread (horn) link 1
Myn's Tuba HT Build Thread (horn) link 2 by mynym and designed by Bill Fitzmaurice
Nate's THT build thread (horn) by natemu06
Peerless XLS10 Subwoofer with Passive Radiator (passive radiator, 10") by Vikash Chauhan
Pi Speakers - 12pi Basshorn (horn, two part kit) by Wayne Parham, Pi Speakers
PPI Pro 12 Vented Sub Build by lowpolyjoe
Project 'Cube 2007 [Rubik's cube sub] (sealed) by Zachary Paisley
Project Quick, Easy & Cheap – IXL18.4 LLT by mynym
Project: Subwoofer (ported, 10", aesthetic, *hall of fame*) by Antti 'Drakmin' Hakala
Project Wolfhorn (horn) by Oklahoma Wolf
Quad Tumults (build thread pending) by kgveteran [this one is awesome]
RB's Tuba HT (horn) by Rightbrained
Ready to DIY; starting with a THT low profile sub (horn) by maxcooper
Reece's THT build just had to be a follower (horn) by reecew
RL-P18 meets the "DOH! button" (ported, 18") by btp
RS1200, The Triska Sub, The Boogieman, The Drake, Rump Thumper (several projects) by various engineers
Russell's Ported Boxes with Cheap Speakers by Russell Burrows
Rythmik 15 Red Oak Sub build (sealed, 15", aesthetic) by rolandtk
Scott's Dual RL-p18 'LLT' twins (ported, 2x18") by Scott Simonian
Sealed Audiopulse Axis 15 times 4!(sealed, 4x15") by toddbagwell
Sealed dual LMS 18" 5400 build by lukeamdman
Sealed Maelstrom-X (sealed, 18") by Willd
Sealed TC Sounds LMS-R 15 Build (15", sealed) by brybo86
Shiva Subwoofer - The Destroyer Has Arrived! (ported, 2x12") by Dan
Single sheet TH challenge (15" horn) by jbelljbell
Sunosub I, II, & III by Patman
SonoSub with Mach5 IXL 15.2.2(sonotube, ported, 15") by salvasol
Subwoofer Made from Sonotube and the Hsu 12" by Ron Stimpson
Subwoofer Project (sealed, 12", aesthetic) by Scott Chilcote
Super THT build thread (horn) by superedge88
Taking my 15" DIY subs to the next level (ported, 15") by Erich H
TC-2000 Sealed (sealed, 15") by Warpdrv
TC Sounds 15" LMS-R in laminated ply enclosure (sealed, 15", aesthetic) by young13
TC Sounds 3000 15" sub (sealed, 15", aesthetic) by spanish68
The 10triple10 - 10" Subwoofer w/3 10" Passive Radiators by Dan
The Biggest SUBWOOFER of the WORLD (horn, *hall of fame*) by Busto Arsizio
The Raven (dual opposed 15" sealed) by bossobass
Thing One and Thing Two (Dayton HF 15's 500w Oaudio) (sealed) by mcsoul
Reed Exodus Anarchy 25hz Tapped Horn (6.5" tapped horn) by radman12 and lilmike
The Reed TubaHT Build (horn) by radman12
The Saint's Folded Horn Subwoofer Project (horn) by Mark Taylor, The Gourmet Saint
The Thrifty Thumper (sealed, 12", aesthetic) by Robert Trim
The Ultimate Pair (passive radiator, 2x15" drivers, 4x18" pr's, minor aesthetic) by Nasty N8
THOR (sealed, 12") by Siegfried Linkwitz
Tremor Twins (ported, 2x15") by Rightbrained
Tuba Home Theater Build by Revolt
Twelve 10" NHT Subwoofer Build(4 sealed enclosures, 3x10" ea.) by Erich H
Two 5cf Dual Opposed MFW-15's Build (dual, 15") by Mpray1983
Usil's 6.3 cuft - 12" Shiva - Ported - Almost Done = Pictures by Usil
Usul: 4 x AE-IB15 line array IB sub by Mike R
Video's 15" TC2000 LLTs (ported, 2x15") by Video
"Washing Machine" Adire Tempest 15" Subwoofer Project (sealed, 15") by Magnetik
What You Can Do With a 21.25" Cube (15" TC-3000/100L sealed/HPSA1000) by Dan
William Cowan's DIY Projects (Tapped Horn, A Tale of 3 12"s, Infinite Baffle, Soffit-Mounted Clamshells, etc.) by William Cowan
Warpdrv's Dual Opposed 18" LMS's..... "The XLerators" (3x dual opposed 18" sealed, aesthetic) by Warpdrv (cabs by AESpeakers)
Wolfhorn SDX (tapped horn) by Oklahoma Wolf
Yet another dual opposed AV15 build (dual 15", sealed, aesthetic) by djarchow
Yet another dual opposed mfw 15 build (dual 15", sealed) by Audiophile34
Yet another THT build... sure, why not? (15", horn) by bbowers
...more to come.
------------------------------------------
Other collections of subwoofers & project ideas:
Bass Horn projects online by diyAudio.com
Best TL Sub Design You Have Seen? at diyAudio.com
DIY Gallery at AVS Forum
DIY Subwoofer Showcase at HTGuide
Member's Subwoofer Database at Home Theater Shack not sure why this link has been busted
http://www.hometheatershack.com/foru...-database.html
Subwoofer & Enclosure Tutorials by JL Audio
Various Horn Projects at speakerplans.com
Econowave build thread. No, not a subwoofer, but since many builds find their way into the subwoofer range:
http://www.audiokarma.org/forums/sho...d.php?t=150939
Historical honorable mentions:
The Acoustic Temple at Skara Brae Constructed circa 3200 bc; in use for roughly 600 years; 135db@1.6hz; by Entheogenic Shaman
[Fast forward to the 29 minute mark in the video for details]
Stonehenge. Resonant frequency of inner circle ~10hz, outer circle ~5hz.
(more later)
.
There are many great subwoofer projects scattered all over the AVSForum as well as the internet. It would be useful to have an index, which is the objective of this thread. Just point to your favorite subwoofer details page and then I will add it to the index. We can figure out how to organize it once we have a nice big list.
12" Peerless XLS dual passive radiator sub project (passive radiator) by Adrian Mack
12" THT is alive! (12", horn) by moab_dan
13.8cubic foot, mach5 IXL18.2.2 build (ported, 18") by N8DOGG
15" TC sound LMS curved box build (sealed, 15", aesthetic, *hall of fame*) by ClintonH
18” down-firing EGG shaped sub build (sealed, 18", aesthetic) by Gmichael2
2 Wolfhorn SDX’s as a riser (horn) by FUN4ME
21" Maelstrom Curved Box Build (sealed, aesthetic) by corock
36" THT^Cube (horn) by dykz34
3.75 cu.ft. sealed sdx15 w/ oaudio 500w plate amp (15" sealed) by RodK
$700 playhouse sub (ported, FI Q18") by scpete26
8x 18" LMS Ultra 5400s in 4 sealed enclosures (sealed, *hall of fame*) by notnyt
8x 18" LMS 5400 Ultras Sealed to 27 Cube 15hz Ported Build (ported, *hall of fame*) by notnyt
Air Supply's DUAL THT/Small Room Build (horn) by Air Supply
Almighty Subwoofers (ported, 15", pro-audio drivers) by Stig Erik Tangen
Altec 18" in 4m long transmission line (transmission line) by Jack Bouska
Bedlam in Goliath: RE Audio XXX18 subwoofer build (ported, 18", *hall of fame*) by Ricci
Bon Voyage! My first DIY subwoofer (sealed, 12") by Danielson99
Building subwoofer using 18LW1400 driver in vented box (slot ported, 21", pro-audio driver) by DL86
Beer Fridge, Sidewinder, Blast Furnace, Snorky, Infinite Baffle, etc. (several projects) by Collo
The BlackReign: 2x21" sealed sub (dual 21" sealed) by scomed99
The Bonecrusher (dual 15" w/quad passive radiators by rightbrained
Canadian_Dude's CSS SDX15 with 2 CSS PR1816 passives (passive radiator) by Canadian_Dude
Collaborative Tapped horn project (tapped horn) by paulspencer
CSS Quartet12 (TRIO12) H in 24" Cube (passive radiator) by caper_1
CSS TRIO12 Front Loaded subwoofer 16hz F3 (horn) by mwmkravchenko
Danley DTS-10 "Super Spud" DIY kit (low-tuned tapped horn) by Tom Danley
Dave's THT Build Thread (horn) by Dave (DL86)
Dave's Quad 18" Fi IB (infinite baffle) by Avus_M3
Dayton 12" 1.2 cu ft (sealed) by Ken Cline
Dayton RS sub project: Assault on SQ (quad 15", sealed, aesthetic) by engr_dave
DIY HiVi SP10 Subwoofer Project (10" ported) by Adam McCall
DIY Duel Front Firing Peerless Sub (sealed, dual 12") by Trofius
Dragonslayr's THT Build (horn) by dragonslayr
DS1200 & DS1500 (sealed and vented, 4 plans) by Rythmik Audio
Dual 15" "Mofo" build (dual sealed) by Jay1
Dual 18" Sub Project (MK II) (dual, ported, 18") by Sam aka s_carter
Dual GR SW-12-08 + Rythmik A370PEQ Servo Sub (sealed, dual 12", aesthetic) by Stereodude
Dual Opposed AV15H Subwoofer Build (sealed, 15") by pdc
Dual opposed sealed JBL GTI MKI 15" sub build (dual 15", sealed) spanish68
Easy Button End Tables 24" x 21" x 36" (slot ported, 18") by NEO Dan
Easy Button End Table MAX 26.5" x 24" x 37.5" (slot ported, 18") by NEO Dan
Ebony and Ivory, dual 18" LMS-5400 Endtables (sealed, aesthetic) by jpmst3
Ezcl's Sub (sealed, 3x12") by Ezcl
eD custom built sub enclosure - TC Sounds 15" LMS-5400 (sealed) by shadowofnight
Ed 16Ov.2 - SF6 = Sealed Box Sub by MegaFlop
Ed 18-inch Sono's (began as 4 ported sonotubes, now 8 sealed sonotubes) by MKtheater
Eric's DIY 12" Subwoofer (short sonotube, ported) by Eric
First Look - TD-18H+ by Tack
Four 18" LMS-5400's (4x18" w/eight passive radiators, aesthetic, *hall of fame*) by robertcharles
Funky Waves 18” LMS 5400 + 2 PR build by lukeamdman
Gjallerhorn (18" LMS tapped horn, *hall of fame*) by Ricci [build details begin on page 11, post #304]
High output 8" Tapped horn (8" tapped horn) by tsloms
Home-Made Home Theater Subwoofer (sealed, 12") by Matt
Infinite Baffle Subwoofer (4x15") by Jonathan Foulkes
Is this wood any good? by javygonx
IXL 18 meets the "Easy Button" (ported, 18") by NEO Dan
Jai's LMS-5400/Passive Radiator design (passive radiator, 18") by jmcomp124
Jason's DIY Subwoofer (Rythmik Audio DS12 kit, sealed, 12") by Jason
JL Audio Enclosures Suggestions for Each Driver
(click on the driver, then scroll down to "Click Here For Recommended Enclosure Specifications")
13W7 Enclosure Specifications by JL Audio
Joining the THT club (dual horns, hall of fame documentation) by notnyt
Karl's Sub Project (sealed, 10") by Karl
LAB Subwoofer Project (horn, *hall of fame (technical)*) by Tom Danley
" http://www.prosoundweb.com/article/lsp_documentation_page_drawings_photos_specs_and_more/ "
(you have to cut and paste the link for this one)
Large.. Dual 15" RL-p Unit(ported, aesthetic) by steve nn
Lilmike's Cinema F-20 (horn) by lilmike
Lilmike's Cinema T-6 (horn) by lilmike
LMS 5400 Ultra X2 Build (18" sealed) by RDKing2
Lord of the Bass: The Two Towers(ported, sonotube, 2x18") by ssabripo
Lord of the Bass: Return of quad Sealed King (sealed, 4x18") by ssabripo
Maelstrom-X PR build...my first DIY by vili
Master SUB Woofer with ETON 12/680/60 HEX (sealed, 12") by Doede Douma
MAW-10 DIY Ported Subwoofer (ported, 10", $110) by Giovanni Militano
MBM - 2 x JBL 2226H by Myggpower
Meet MadMAX (HUGE horn) designed by Maxmercy, built by MX48 aka Moto
MFW-15 Project Advice Needed (15" sealed) by Scott C
My first TC SOUNDS DIY sub! by maintrain
Myn's Tuba HT Build Thread (horn) link 1
Myn's Tuba HT Build Thread (horn) link 2 by mynym and designed by Bill Fitzmaurice
Nate's THT build thread (horn) by natemu06
Peerless XLS10 Subwoofer with Passive Radiator (passive radiator, 10") by Vikash Chauhan
Pi Speakers - 12pi Basshorn (horn, two part kit) by Wayne Parham, Pi Speakers
PPI Pro 12 Vented Sub Build by lowpolyjoe
Project 'Cube 2007 [Rubik's cube sub] (sealed) by Zachary Paisley
Project Quick, Easy & Cheap – IXL18.4 LLT by mynym
Project: Subwoofer (ported, 10", aesthetic, *hall of fame*) by Antti 'Drakmin' Hakala
Project Wolfhorn (horn) by Oklahoma Wolf
Quad Tumults (build thread pending) by kgveteran [this one is awesome]
RB's Tuba HT (horn) by Rightbrained
Ready to DIY; starting with a THT low profile sub (horn) by maxcooper
Reece's THT build just had to be a follower (horn) by reecew
RL-P18 meets the "DOH! button" (ported, 18") by btp
RS1200, The Triska Sub, The Boogieman, The Drake, Rump Thumper (several projects) by various engineers
Russell's Ported Boxes with Cheap Speakers by Russell Burrows
Rythmik 15 Red Oak Sub build (sealed, 15", aesthetic) by rolandtk
Scott's Dual RL-p18 'LLT' twins (ported, 2x18") by Scott Simonian
Sealed Audiopulse Axis 15 times 4!(sealed, 4x15") by toddbagwell
Sealed dual LMS 18" 5400 build by lukeamdman
Sealed Maelstrom-X (sealed, 18") by Willd
Sealed TC Sounds LMS-R 15 Build (15", sealed) by brybo86
Shiva Subwoofer - The Destroyer Has Arrived! (ported, 2x12") by Dan
Single sheet TH challenge (15" horn) by jbelljbell
Sunosub I, II, & III by Patman
SonoSub with Mach5 IXL 15.2.2(sonotube, ported, 15") by salvasol
Subwoofer Made from Sonotube and the Hsu 12" by Ron Stimpson
Subwoofer Project (sealed, 12", aesthetic) by Scott Chilcote
Super THT build thread (horn) by superedge88
Taking my 15" DIY subs to the next level (ported, 15") by Erich H
TC-2000 Sealed (sealed, 15") by Warpdrv
TC Sounds 15" LMS-R in laminated ply enclosure (sealed, 15", aesthetic) by young13
TC Sounds 3000 15" sub (sealed, 15", aesthetic) by spanish68
The 10triple10 - 10" Subwoofer w/3 10" Passive Radiators by Dan
The Biggest SUBWOOFER of the WORLD (horn, *hall of fame*) by Busto Arsizio
The Raven (dual opposed 15" sealed) by bossobass
Thing One and Thing Two (Dayton HF 15's 500w Oaudio) (sealed) by mcsoul
Reed Exodus Anarchy 25hz Tapped Horn (6.5" tapped horn) by radman12 and lilmike
The Reed TubaHT Build (horn) by radman12
The Saint's Folded Horn Subwoofer Project (horn) by Mark Taylor, The Gourmet Saint
The Thrifty Thumper (sealed, 12", aesthetic) by Robert Trim
The Ultimate Pair (passive radiator, 2x15" drivers, 4x18" pr's, minor aesthetic) by Nasty N8
THOR (sealed, 12") by Siegfried Linkwitz
Tremor Twins (ported, 2x15") by Rightbrained
Tuba Home Theater Build by Revolt
Twelve 10" NHT Subwoofer Build(4 sealed enclosures, 3x10" ea.) by Erich H
Two 5cf Dual Opposed MFW-15's Build (dual, 15") by Mpray1983
Usil's 6.3 cuft - 12" Shiva - Ported - Almost Done = Pictures by Usil
Usul: 4 x AE-IB15 line array IB sub by Mike R
Video's 15" TC2000 LLTs (ported, 2x15") by Video
"Washing Machine" Adire Tempest 15" Subwoofer Project (sealed, 15") by Magnetik
What You Can Do With a 21.25" Cube (15" TC-3000/100L sealed/HPSA1000) by Dan
William Cowan's DIY Projects (Tapped Horn, A Tale of 3 12"s, Infinite Baffle, Soffit-Mounted Clamshells, etc.) by William Cowan
Warpdrv's Dual Opposed 18" LMS's..... "The XLerators" (3x dual opposed 18" sealed, aesthetic) by Warpdrv (cabs by AESpeakers)
Wolfhorn SDX (tapped horn) by Oklahoma Wolf
Yet another dual opposed AV15 build (dual 15", sealed, aesthetic) by djarchow
Yet another dual opposed mfw 15 build (dual 15", sealed) by Audiophile34
Yet another THT build... sure, why not? (15", horn) by bbowers
...more to come.
------------------------------------------
Other collections of subwoofers & project ideas:
Bass Horn projects online by diyAudio.com
Best TL Sub Design You Have Seen? at diyAudio.com
DIY Gallery at AVS Forum
DIY Subwoofer Showcase at HTGuide
Member's Subwoofer Database at Home Theater Shack not sure why this link has been busted
http://www.hometheatershack.com/foru...-database.html
Subwoofer & Enclosure Tutorials by JL Audio
Various Horn Projects at speakerplans.com
Econowave build thread. No, not a subwoofer, but since many builds find their way into the subwoofer range:
http://www.audiokarma.org/forums/sho...d.php?t=150939
Historical honorable mentions:
The Acoustic Temple at Skara Brae Constructed circa 3200 bc; in use for roughly 600 years; 135db@1.6hz; by Entheogenic Shaman
[Fast forward to the 29 minute mark in the video for details]
Stonehenge. Resonant frequency of inner circle ~10hz, outer circle ~5hz.
(more later)
.