Pair Monacor SP-60/4 in a stuffed port aperiodic cabinet? What size cabinet? - diyAudio
Go Back   Home > Forums > Loudspeakers > Multi-Way

Multi-Way Conventional loudspeakers with crossovers

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 13th September 2012, 02:57 AM   #1
diyAudio Member
 
danielwritesbac's Avatar
 
Join Date: Nov 2007
Default Pair Monacor SP-60/4 in a stuffed port aperiodic cabinet? What size cabinet?

I'm building a portable, outdoor pa use, portable speaker to fit a bicycle rack. Winisd's ported box figure for a pair of Monacor SP-60/4 was too big and didn't seem to represent any stuffing, so either ported or stuffed port is fine, but the WinISD size is not. I also need cabinet bass emphasis to about +5 for outdoor use tuning and that should help to shrink the size a bit.

I've really no clue for cabinet size (the pair in a single cabinet). Help?
I need your suggestions.

Here's some figures for the speaker.
Impedance (Z) 4Ω
Resonant frequency (fs) 65Hz
Suspension compl. (Cms) 0.8mm/N
Moving mass (Mms) 4g
Mech. Q factor (Qms) 2.10
Electr. Q factor (Qes) 0.64
Total Q factor (Qts) 0.49
Equivalent volume (Vas) 6 l
DC resistance (Re) 3.3Ω
Force factor (BxL) 2.9Tm
Voice coil induct. (Le) 0.2mH
Voice coil diameter 25.5mm
Linear excursion (XMAX) 2mm
Eff. cone area (Sd) 55cm2
__________________
Tools, Models & Software for DIYClipNipper boostLM1875 TurboPowerful TDA7293 kitTDA7294 pt2pt ♦ My post has opinion.
  Reply With Quote
Old 13th September 2012, 06:31 AM   #2
diyAudio Member
 
danielwritesbac's Avatar
 
Join Date: Nov 2007
WinISD seems to say that the pair of woofers fits a 10.5 liter box, if minimum sized, and any smaller would be much harder to tune. Is that correct?
So, my question is, would an aperiodic go a smaller and/or have more bass extension than ported?

P.S.
Also driving each woofer from a series cap, of 1000u (-0db@80hz, -3db@60hz -6db@40hz), to give the TA2020 battery powered amplifier decreased load at subharmonic (running 60z at 1/2 power, 40hz at 1/4 power saves the battery) and, in theory, slightly flub the electronic dampening at lowest pitches to fit smaller box. That's a modest trick at best. Yet, in a 0.5l cardboard box, one of these little woofers is doing unexpectedly well on bass.
__________________
Tools, Models & Software for DIYClipNipper boostLM1875 TurboPowerful TDA7293 kitTDA7294 pt2pt ♦ My post has opinion.
  Reply With Quote
Old 13th September 2012, 11:10 AM   #3
diyAudio Member
 
chris661's Avatar
 
Join Date: Feb 2008
Location: Sheffield
Blog Entries: 8
I'd put the series cap at line level - at speaker level it'll interact with the impedance peaks in interesting ways (usually a peak in output at each impedance peak - when one of the peaks is below port tuning, this isn't desirable).

For outdoors use, its worth avoiding a flat alignment - its difficult to get LF outdoors, so (using a trick that's been in the HiFi industry for years) use the port to create a bump in the response before rolloff - that way, it sounds like there's bass without there being any.

Chris
  Reply With Quote
Old 13th September 2012, 11:45 AM   #4
diyAudio Member
 
mondogenerator's Avatar
 
Join Date: Sep 2009
Location: City Of Villans
Blog Entries: 1
if im not mistaken the cap is for QB5 (I or II?) alignment. However, im not sure if the OP goal is to extend bass or increase power handling. Im guessing the former.
__________________
Every new piece of knowledge pushes something else out of my brain - Homer.....................Simpson
  Reply With Quote
Old 13th September 2012, 11:50 AM   #5
diyAudio Member
 
Saturnus's Avatar
 
Join Date: Jun 2005
Location: Copenhagen, Denmark
For optimum "boombox" tuning intended for outdoors use. You need to tune the cabinet to Q=1.207, instead of Q=0.707 as is the normal compromise used in indoors intended (home stereo) speakers. The result will be roughly same in audio quality, so pay no heed to people saying that it will have sloppy bass as that is not the case. In fact in audio quallty, you can basically say that outdoor Q/2 = indoors Q. So it's in fact even better dampened at Q=1.207 than an indoors speaker is at Q=0.707.

To figure out the optimum cabinet size, use winISD or other software and assume Q=0.707. Take the Vb (box volume) from that and divide with Pi. And take the Fb (box resosnant frequency) and multiply by square root of 2.

In short:

Indoors Q = outdoors Q / 2 (assumes that we compare speakers in a small room to semi-free field where speaker is relatively close to ground)
Vb = Vb / Pi
Fb = Fb * 2^0.5

As for using a series cap. Don't bother. Change the input cap on the amp instead.

Last edited by Saturnus; 13th September 2012 at 11:58 AM.
  Reply With Quote
Old 13th September 2012, 11:54 AM   #6
diyAudio Member
 
mondogenerator's Avatar
 
Join Date: Sep 2009
Location: City Of Villans
Blog Entries: 1
+1 good point Saturnus
__________________
Every new piece of knowledge pushes something else out of my brain - Homer.....................Simpson
  Reply With Quote
Old 13th September 2012, 12:15 PM   #7
diyAudio Member
 
Saturnus's Avatar
 
Join Date: Jun 2005
Location: Copenhagen, Denmark
To further expand on the above.

If you plot the new Vb and Fb figures into winISD, you'll notice a 2.83dB peak (usually) somewhere in the 120-160Hz area. In psychoacoustic effect that corresponds to being perceived as flat to that frequency divided with square root of 2. So if it peaks at 144Hz, it's perceived flat to 100Hz.

In principle perceived flat means exactly that. Output without noticable loss. So it doesn't correspond to the normal -3dB point which is the frequency where output is noticeably lower but rather the start of the roll-off in regular tuning. For something that corresponds closely to a -3dB point, assume that it goes about 10% lower in frequency than the above calculation indicate as the flat frequency range.

Last edited by Saturnus; 13th September 2012 at 12:25 PM.
  Reply With Quote
Old 13th September 2012, 03:50 PM   #8
sreten is offline sreten  United Kingdom
diyAudio Member
 
Join Date: Nov 2003
Location: Brighton UK
Hi,

You can use the demo version of Basta! to model the
effects of series capacitor interaction with the speaker.

rgds, sreten.
__________________
There is nothing so practical as a really good theory - Ludwig Boltzmann
When your only tool is a hammer, every problem looks like a nail - Abraham Maslow
  Reply With Quote
Old 13th September 2012, 05:17 PM   #9
diyAudio Member
 
danielwritesbac's Avatar
 
Join Date: Nov 2007
Quote:
Originally Posted by Saturnus View Post
Indoors Q = outdoors Q / 2 (assumes that we compare speakers in a small room to semi-free field where speaker is relatively close to ground)
Vb = Vb / Pi
Fb = Fb * 2^0.5
Seems good, but unfortunately I couldn't read it well enough to do the maths, there being no similar examples to follow for decoding it. So, what's the cabinet size?

When playing with the WinISD, I was going for attempting a +5 bump on the bass for outdoor tuning. That got it down to 10.5l. Could it be made smaller?
__________________
Tools, Models & Software for DIYClipNipper boostLM1875 TurboPowerful TDA7293 kitTDA7294 pt2pt ♦ My post has opinion.
  Reply With Quote
Old 13th September 2012, 07:55 PM   #10
diyAudio Member
 
Saturnus's Avatar
 
Join Date: Jun 2005
Location: Copenhagen, Denmark
Quote:
Originally Posted by danielwritesbac View Post
Seems good, but unfortunately I couldn't read it well enough to do the maths...
No idea what the problem is but I'll just let these 2 pictures explain it instead.
Attached Images
File Type: jpg Monacor1.JPG (45.7 KB, 384 views)
File Type: jpg Monacor2.JPG (44.8 KB, 364 views)
  Reply With Quote

Reply


Hide 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
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Recommend 8" Driver for Aperiodic Cabinet konut Subwoofers 4 17th September 2008 11:16 AM
Sealed sub: cabinet size?? Klimon Subwoofers 4 10th August 2006 11:26 AM
Cabinet Size of Satelites ??? ralph-bway Multi-Way 2 29th October 2003 09:51 AM
Reflex port under the cabinet ?? gary f Multi-Way 21 26th October 2003 10:17 PM
Monacor SP 60/8 needed Cambe Swap Meet 1 1st August 2002 12:59 PM


New To Site? Need Help?

All times are GMT. The time now is 02:59 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2