Speakerplans.com Homepage
Forum Home Forum Home > Plans > New Projects Forum
  New Posts New Posts RSS Feed - Garage Sub
  FAQ FAQ  Forum Search   Events   Register Register  Login Login

Garage Sub

 Post Reply Post Reply
Author
Message
NevilleT View Drop Down
New Member
New Member
Avatar

Joined: 04 May 2022
Location: Southampton
Status: Offline
Points: 6
Post Options Post Options   Thanks (0) Thanks(0)   Quote NevilleT Quote  Post ReplyReply Direct Link To This Post Topic: Garage Sub
    Posted: 04 May 2022 at 7:13pm
Hi All,

I want to make a sub that will fit under my bench in my garage workshop.

I have some fixed design points:

The enclosure will be made of 18mm birch ply and needs to have the following external dims:

695 mm width
450mm high
350mm deep

The driver I intend to use is a JBL 15" M252-8 (specs below)

I plan to use a Behringer Ultradrive Pro controller and a Thomann T-Amp S100 which can be configured in bridge mode if required.

I have no particular preference on whether the enclosure is closed or vented - but if vented, then something I can make in the workshop like an oblong 'tube'.

So I'd like some suggestions on the enclosure type/bracing/filling/etc.

Many thanks in advance

Nev


Fs(Hz) 50.7
Vas(l) 137
Qts 0.56
Qms 4.6
Qes 0.643
Bl(Tm) 12.8
Mms(gr) 79
Cms(mm/N) 0.125
Rms(kg/s) 5.45
Le(mH) 0.43
Re(Ohm) 4.2
Sd(sq.mm) 88000
Vd(l) 0.559
X-max(mm) 6
X-mech(mm) 0
Diameter (inch) 15
Max Power(W.) 600
RMS Power(W.) 300
Number of Coils 1
Impedance Z-Nom(Ohm) 8
Reference efficiency ?0(%) 2.68
Sensitivity(dB) 1-W 96.3
Sensitivity(dB) 2.8-V 99.1
Back to Top
Elliot Thompson View Drop Down
Old Croc
Old Croc
Avatar

Joined: 02 April 2004
Location: United States
Status: Online
Points: 4982
Post Options Post Options   Thanks (0) Thanks(0)   Quote Elliot Thompson Quote  Post ReplyReply Direct Link To This Post Posted: 05 May 2022 at 1:52pm
That is a very small box for a driver offering the above TS Parameters. Reflex would be your best option. As for Bracing, this box is already too small for the driver in question. The last thing you want to do is lose even more internal space with bracing. Damping will tone down the standing waves which will be very helpful as the box will ring like a bell due to using a driver with the above TS Parameters in such a small enclosure.  

Best Regards, 


Edited by Elliot Thompson - 05 May 2022 at 1:54pm
Elliot Thompson
Back to Top
NevilleT View Drop Down
New Member
New Member
Avatar

Joined: 04 May 2022
Location: Southampton
Status: Offline
Points: 6
Post Options Post Options   Thanks (0) Thanks(0)   Quote NevilleT Quote  Post ReplyReply Direct Link To This Post Posted: 05 May 2022 at 2:04pm
Many thanks for your help.

So a smaller driver then?  a "12 or maybe a "10?

Ringing like a bell is not what I want..
Back to Top
Elliot Thompson View Drop Down
Old Croc
Old Croc
Avatar

Joined: 02 April 2004
Location: United States
Status: Online
Points: 4982
Post Options Post Options   Thanks (0) Thanks(0)   Quote Elliot Thompson Quote  Post ReplyReply Direct Link To This Post Posted: 05 May 2022 at 2:11pm
Yes. The smaller the driver, the greater the chances of the driver seeing the fixed cabinet dimensions as a larger enclosure. The TS Parameters will still play a factor of course! That JBL would give you a -3 dB around 54 Hz - 59 Hz in such an enclosure. 

Best Regards,
Elliot Thompson
Back to Top
NevilleT View Drop Down
New Member
New Member
Avatar

Joined: 04 May 2022
Location: Southampton
Status: Offline
Points: 6
Post Options Post Options   Thanks (0) Thanks(0)   Quote NevilleT Quote  Post ReplyReply Direct Link To This Post Posted: 05 May 2022 at 2:28pm
I also have this 12" driver kicking around.. So would this be better?

Eminence Beta 12CX
Nominal Basket Diameter 12", 304.8mm
Nominal Impedance* 8 ohms
Power Rating: Watts 250W, Music Program 500W
Resonance 47Hz
Usable Frequency Range 57Hz - 4.6kHz
Sensitivity*** 97.3B
Magnet Weight 38 oz.
Gap Height 0.31", 7.92mm
Voice Coil Diameter 2", 50.8mm


Thiele & Small Parameters:

Resonant Frequency (fs) 47Hz
DC Resistance (Re) 5.42 ohms
Coil Inductance (Le) 0.64mH
Mechanical Q (Qms) 5.64
Electromagnetic Q (Qes) 0.52
Total Q (Qts) 0.48
Compliance Equivalent Volume (Vas) 120.94 liters / 4.27 cu.ft.
Peak Diaphragm Displacement Volume (Vd) 188.6cc
Mechanical Compliance of Suspension (Cms) 0.3mm/N
BL Product (BL) 10.79 T-M
Diaphragm Mass Inc. Airload (MMs) 38 grams
Efficiency Bandwidth Product (EBP) 90
Maximum Linear Excursion (Xmax) 3.5mm
Surface Area of Cone (Sd) 538.9 cm2
Maximum Mechanical Limit (Xlim) 10.4mm


Mounting Information:

Recommended Enclosure Volume: Sealed 26.9-70.79 liters / 0.95-2.5 cu.ft., Vented 32.85-158.58 liters / 1.16-5.6 cu.ft.
Driver Volume Displaced 0.071 cu.ft. / 2 liters
Overall Diameter 12.03", 305.6mm
Baffle Hole Diameter 11.07", 281.2mm
Front Sealing Gasket Fitted as standard
Rear Sealing Gasket Fitted as standard
Mounting Holes Diameter 0.25", 6.4mm
Mounting Holes B.C.D. 11.59", 294.3mm
Depth 4.47", 113.5mm
Net Weight 7.8 lbs, 3.54 kg
Shipping Weight 10 lbs, 4.54 kgs
Back to Top
Elliot Thompson View Drop Down
Old Croc
Old Croc
Avatar

Joined: 02 April 2004
Location: United States
Status: Online
Points: 4982
Post Options Post Options   Thanks (0) Thanks(0)   Quote Elliot Thompson Quote  Post ReplyReply Direct Link To This Post Posted: 05 May 2022 at 2:41pm
The standing waves are reduced and, you should be around -3 dB @ 49.6 Hz. It is a coaxial speaker so it is aimed for Full-range (using a screw-on compression driver) usage. What else do you have?

Best Regards, 
Elliot Thompson
Back to Top
NevilleT View Drop Down
New Member
New Member
Avatar

Joined: 04 May 2022
Location: Southampton
Status: Offline
Points: 6
Post Options Post Options   Thanks (0) Thanks(0)   Quote NevilleT Quote  Post ReplyReply Direct Link To This Post Posted: 05 May 2022 at 7:07pm
I tend to screw old drivers to the roof of my workshop and there is a motley collection...
I have some very old 12" Fane & McKenzie drivers from guitar amps i'm guessing wouldn't great for a sub.  I also have some dual concentric 6"? Tannoy drivers from some DC2000 HiFi speakers.
These cabinets had two drivers. The bass ones had a surround that perished.  The top speakers were dual concentric and those are still viable.  Helpfully there are no usefull markings on them so I have no idea what the specs would be.
Back to Top
ceharden View Drop Down
The 10,000 Points Club
The 10,000 Points Club
Avatar

Joined: 05 June 2005
Location: Southampton
Status: Offline
Points: 11667
Post Options Post Options   Thanks (0) Thanks(0)   Quote ceharden Quote  Post ReplyReply Direct Link To This Post Posted: 05 May 2022 at 10:43pm
Hi Neville! Welcome to Speakerplans! I'm trying to think if I have anything knocking around which might work in such a cab.  I might have a 12" which I was saving for a bass guitar project but enough years have passed that I probably won't ever get round to it!
Back to Top
NevilleT View Drop Down
New Member
New Member
Avatar

Joined: 04 May 2022
Location: Southampton
Status: Offline
Points: 6
Post Options Post Options   Thanks (0) Thanks(0)   Quote NevilleT Quote  Post ReplyReply Direct Link To This Post Posted: 06 May 2022 at 11:22am
Hi Chris!  We need to talk!  Drop round for a coffee.
Please email at nevillet01@gmail.com

Back to Top
Lucasdude View Drop Down
Registered User
Registered User


Joined: 16 March 2013
Location: London
Status: Offline
Points: 471
Post Options Post Options   Thanks (0) Thanks(0)   Quote Lucasdude Quote  Post ReplyReply Direct Link To This Post Posted: 06 May 2022 at 5:26pm
I had some of those M252-8 drivers many years ago in some JBL I745 dual reflex cabs. They sounded awful. I tried them in some other bass cabs and they also sounded very poor. I suspect drivers with a very low BL like those are better suited to bass/mid than sub duties, even though the I745 had annoying NL8 sockets and were marked "VLF" for their connection!


Edited by Lucasdude - 06 May 2022 at 5:28pm
Back to Top
 Post Reply Post Reply

Forum Jump Forum Permissions View Drop Down

Forum Software by Web Wiz Forums® version 12.05
Copyright ©2001-2022 Web Wiz Ltd.

This page was generated in 0.109 seconds.