Pair Monacor SP-60/4 in a stuffed port aperiodic cabinet? What size cabinet? - Page 2 - diyAudio
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Old 13th September 2012, 08:23 PM   #11
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Thank you!
My USA university education was enough to avoid making WinISD's implausible footlockers, but not enough to replace that with the right size cabinet. Since the cabinet sizes you've shown look much more plausible/practical, I would love to know what software you've used?

Anyway, if I read it right, that software gives accurate close box figures and I subtract a third of the box for ported.

It appears to be for a single driver. Am I correct in assuming that 3.63l *2 is suitable for 2 of Monacor SP-60/4? Inflating the cabinet to make room for my epic amount of circuit boards and the batteries results in an estimated 8l size cabinet. Correct?
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Old 13th September 2012, 09:17 PM   #12
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With 6mm hardened birch composite, my enclosure size for 2 Monacor sp-60/4 is?
23.5cm (slightly below saddle height)
13.4cm (slightly wider than bicycle rack)
31cm (slightly longer than bicycle rack)
This fits the bicycle well.
I hope the size is right for the speakers.
Starting to cut lumber. . .

Remaining question:
Number of port tube(s)?
Diameter of port tube(s)?
Location of port tube(s)?
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Old 14th September 2012, 03:48 AM   #13
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Quote:
Originally Posted by danielwritesbac View Post
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
FYI, when I load the theoretically most accurate specs [Sd, Re, Cms, Mms, BL, Qms], WinISD Pro calculates significantly different specs than T/S, making the cab significantly larger & tuned higher.

GM
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Old 15th September 2012, 07:04 AM   #14
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Default Cabinet photo

Slightly steampunk?
Anyway, still sanding. . .
P.S.
What's the recommended location(s) and diameters(s) for the port tube(s)?
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Last edited by danielwritesbac; 15th September 2012 at 07:13 AM.
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Old 15th September 2012, 11:01 PM   #15
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Quote:
Originally Posted by danielwritesbac View Post
Am I correct in assuming that 3.63l *2 is suitable for 2 of Monacor SP-60/4?
To maintain the same response, tuning, yes. Note that the number of vents double also. That, or a single larger one that maintains ~ the same vent efficiency.

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Old 16th September 2012, 02:54 AM   #16
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Default Vents?

Two small vents/ports less boomy than one large vent/port?
Well, for the enclosure pictured in post 14, where do the vents/ports go?
I'm not experienced with ported speakers (except for refit/repair jobs), so I need someone experienced to tell me where to put the holes. Help?

P.S.
There is a speaker for the largest panel on front and there is a speaker for the largest panel on back. It is a bipolar outdoor speaker arranged for maximum broadcast range.
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Old 17th September 2012, 12:36 AM   #17
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Quote:
Originally Posted by danielwritesbac View Post
Remaining question:
Number of port tube(s)?
Diameter of port tube(s)?
Location of port tube(s)?
Depends on what physically fits best overall.

Depends on the amount of power they need to handle at a low vent mach [air velocity], i.e. < ~17.2 m/sec at box tuning [Fb].

What Fb are you planning to use and how much power are the drivers likely to need and/or is available?

In acoustically small cabs, i.e. its pass-band WLs are very large compared to the vet box volume [Vb], vents can be positioned anywhere and they will still seamlessly sum, so wherever on the cab it’s convenient.

GM
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Old 17th September 2012, 12:37 AM   #18
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Quote:
Originally Posted by danielwritesbac View Post
Two small vents/ports less boomy than one large vent/port?
Not if they have ~the same efficiency, i.e. vent mach. When there’s lots of vents Vs one though, such as an Onken alignment, there will be differing audible performance due to the individual vent’s harmonic structure, acoustical damping.

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Old 17th September 2012, 10:11 PM   #19
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Quote:
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What Fb are you planning to use and how much power are the drivers likely to need and/or is available?
I don't know how to answer the FB question, except that I'm trying to stay near the specs that Saturnus posted. I pepped up the cabinet size slightly, to make room for frame, braces, batteries, and quite a few circuit boards.

Amp power:
TA2020+ClipNipper running on solar+battery in the range of ~12v to 15.3v (overcharge protect drainers have switched on at 15.3v, amp actually runs normally at typical automotive voltages 13.5 to 14.8 range). There's also a dual asymmetric soft clipper installed at input to help prevent x-max. The soft clippers and the limiter were both aligned while the amp was running from a 12vdc regulated source. So, consider 20 watts per channel +5db more headroom.

Quote:
Originally Posted by GM View Post
Not if they have ~the same efficiency, i.e. vent mach. When there’s lots of vents Vs one though, such as an Onken alignment, there will be differing audible performance due to the individual vent’s harmonic structure, acoustical damping.
I do favor a greater number of smaller ports, sounds more like aperiodic (less boomy) but easier to calculate. But I don't know how many ports to use.
There's speaker drivers on both sides of the enclosure, and so for balanced stereo, do I need ports on both sides of the enclosure?
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Last edited by danielwritesbac; 17th September 2012 at 10:14 PM.
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Old 19th September 2012, 02:56 AM   #20
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OK, so a ~75.33 Hz tuning [Fb].

OK, with this tuning you’ll run out of linear travel at ~2 W, so allowing for a little overdrive, 5 W max below Fb. Hope your limiter never fails.

At only 5 W, the vents can be quite small, 2.5 cm dia. x 5.3 cm long.

Again, you can put the vents wherever they will fit since the diameter of a 75 Hz WL is ~57.55” and/or where they sound best overall to you, though in theory you shouldn’t be able to hear any difference unless you overdrive the cab so hard that the vents audibly ‘whistle’/’chuff’.

That said, the pioneers of audio concluded that for a simple reflex like this one, putting the vents as close as practical to the driver is best overall, so your call.

GM
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