Input on these two drivers for a small sealed sub?

[peace brainerd]

I'm building a small budget home theater sub for limited space and for very low to moderate listening.

I've got limited room so I'm going to make it as flat and wide/long as possible.

I plan on using a pair of either of the two drivers listed below wired 4 ohm. Look like very good price values.

Does either driver look better suited for the idea? They both appear to be ok for sealed or ported. I'd prefer sealed. I do realize that xmax is limited for sub use, but pairing them helps a bit and I done enough diy'ing
to be confident that this won't be a limitation for my listening preferences.

Can anyone offer suggestions for Internal dimensions for a sealed box for either of these drivers paired?

I'd like to mount them side/side bottom firing and will be using this amp...

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An externally hosted image should be here but it was not working when we last tested it.

MCM Audio Select 50 Watt Subwoofer Amplifier Module | 50-6268 (506268) |
$39.99

• Fully adjustable 12dB/octave crossover from 70Hz~150Hz
• Overload, thermal and fuse protection
• High density trim gasket
• LED indicator light that can be custom mounted

Specifications:

• Minimum speaker impedance: 4ohm
• Power output (RMS): 50W @ 4ohm, 30W @ 8ohm
• THD: 0.1%
• S/N ratio: Greater than 90dB
• Power requirements: 120VAC, 60/50Hz
• Overall dimensions: 10 ? (H) x 5 ¾" (W) x 4" (D)
• Required cutout: 9 ¼" (H) x 4 ½" (W)

An externally hosted image should be here but it was not working when we last tested it.

An externally hosted image should be here but it was not working when we last tested it.

MCM Audio Select 6 1/2'' Polypropylene Cone Woofer | 55-1185 MCM Audio Select 6 1/2'' Woven Carbon Fiber Cone Woofer | 55-1545 |
$12.49 /// $13.49

Polypropylene cone /// Carbon fiber cone
Rubber surround /// Rubber surround
Stamped steel basket /// Stamped steel basket
1" voice coil /// 1.25" voice coil
17.7oz. magnet /// 17.7oz. magnet
Specifications:: Power Capacity: 45W/60W RMS/peak /// 50W/100W RMS/peak
Sensitivity: 87dB (W/M) ///86dB (W/M)
Impedance: 8ohm /// 8ohm
Re: 6.0ohm /// 6.6ohm
Le: 0.44mH /// 1.39mH
Frequency response: 40Hz~7KHz /// 35Hz~6KHz
Fs: 40Hz /// 35Hz
Qts: 0.50 /// 0.39
Qes: 0.66 /// 0.42
Qms: 2.07 ///5.51
Vas: 29.65 (liters) /// 32.27 (liters)
Xmax: 2.4mm /// 2.5mm
Frame diameter 7.40 /// 6.50

(Frame diameter of the carbon fiber woofer is almost an inch larger so the SD of these drivers appears to be comparable
despite the appearances in the photos)

Thanks so much for any help.

 

[peace brainerd]

8 inchers Probably a much better choice, paired, for just a couple of bucks more?
Or are the 6.5 inchers just fine for what I'm talking about building?

An externally hosted image should be here but it was not working when we last tested it.

An externally hosted image should be here but it was not working when we last tested it.

MCM Audio Select 8'' Polypropylene Cone Woofer | 55-1190 (551190) | MCM Audio Select 8'' Woven Carbon Fiber Cone Woofer | 55-1550 (551550) |

$15.29 /// $19.99
Polypropylene cone/// Carbon fiber cone
Rubber surround /// Rubber surround
Stamped steel basket /// Stamped steel basket
1" voice coil /// 1.5 inch voice coil
17.7oz. magnet /// 30oz magnet

Specifications::
Power Capacity: 70W/100W RMS/peak /// Power Capacity: 75W/150W RMS/peak
Sensitivity: 87dB (W/M) /// Sensitivity: 90db (W/M)
Impedance: 8ohm /// Impedance: 8ohm
Re: 6.8ohm /// Re: 6.0ohm
Le: 0.63mH /// Le: 1.55mH
Frequency response: 30Hz~3.5KHz /// Frequency response 30Hz-5KHz
Fs: 31Hz /// Fs: 30Hz
Qts: 0.55 /// Qts: 0.35
Qes: 0.77 /// Qes: 0.37
Qms: 1.89 /// Qms: 4.37
Vas: 65.76 (liters) /// Vas: 59.01 (liters)
Xmax: 3.8mm Xmax: 1.5mm


Wow. Where the heck did that 1.5mm Xmax come from? That's really cutting it close.
The 10 inch version of this driver jumps from 20 dollars to 55 dollars with just about the same specs so this is where the
good value kind of diminishes quickly.

1.5mm xmax work out ok for paired drivers at very low to moderate listening? No doubt it's longer throw than the tiny paper 4/5 inch
driver that's in the cheapo Sony sub that's currently under my 50" plasma television. I've never bottomed that one out but it's really easy
to run it into distortion.

 

[richie00boy]

The polypropylene version of either of those two as you need the higher Qts in a sealed sub to help you get lower. What is your size limit? As I think you may not be too happy with the box size needed.

 

[peace brainerd]

Don't understand. I thought Qts was the most significant single TS parameter as well when considering sealed/ported.

But this website seems to suggest another calc...
Sealed or Ported Enclosure Calculator

....and inputting the Fs and Qes from any of these drivers does not even seem calculable according to their inputs.
I click and it just gives me a zero. Did I miss a step?

Sealed or Ported Enclosure Calculator Help

Efficiency Bandwidth Product (EBP) = Free Air Resonance (Fs) / Driver Electrical "Q" (Qes)

Just doing this manually seems to give me .8333 How is that supposed to be represented on a 0-200 scale?

Here's where that "get help for the sealed vs ported calculator" brings me.....

So I tried to follow through the rest of the site using the parameters for that MCM 8inch poly cone driver.
This is what I get from the same webpages using their simple box calculator

What about that first matter of EPB = Fs/Qes ?
There are no options for inputting paired/dual drivers.
Is there a freeware calculator out there that will do so?

 

[bjorno]

Don't understand. I thought Qts was the most significant single TS parameter as well when considering sealed/ported.

But this website seems to suggest another calc...
Sealed or Ported Enclosure Calculator

....and inputting the Fs and Qes from any of these drivers does not even seem calculable according to their inputs.
I click and it just gives me a zero. Did I miss a step?

Sealed or Ported Enclosure Calculator Help
Just doing this manually seems to give me .8333 How is that supposed to be represented on a 0-200 scale?

Here's where that "get help for the sealed vs ported calculator" brings me.....

So I tried to follow through the rest of the site using the parameters for that MCM 8inch poly cone driver.
This is what I get from the same webpages using their simple box calculator

What about that first matter of EPB = Fs/Qes ?
There are no options for inputting paired/dual drivers.
Is there a freeware calculator out there that will do so?

Hi,

You’ve entered Qes= 42 but should be 0.42. Then Vas should be 32.27L or 1.1396 cu.ft.

That's why all came out wrong.

The EBP = Energy Bandwidth Product is an indicator of speaker type suitability, i,e. both suggested drivers would do well in a closed or in a ported box but the carbon coned would be better to use in a ported box..

b🙂

 

[peace brainerd]

You’ve entered Qes= 42 but should be 0.42. Then Vas should be 32.27L or 1.1396 cu.ft.

That's why all came out wrong.

An externally hosted image should be here but it was not working when we last tested it.

Thanks for that. I'm an idiot.

For a sealed box it's kid of a decision between the 6.5 and the 8 inch driver. I'll have to do some more plugging in and figuring out volume for dual drivers.

 

[bender460]

Here is an option for you.. Using two 6.5" MCM drivers. Makes a nice sounding little sub.

MCM Audio Select 6 1/2'' High Excursion Aluminum Cone Woofer | 55-1862 (551862) | MCM Audio Select

 

[tb46]

Hi peace brainerd,

It's a long time ago, but my experience with the inexpensive MCM woofers has been that their T/S parameters have no relationship to the product. I ended up having to use the drivers I received in isobaric arrangements to make them work (the 55-2421 being somewhat of an exception to the rule). In other words: don't spend too much time designing before you have measured the drivers.

If you're looking for 6-1/2" woofers, how about the 55-2970 for $5.99 ea ($5.39ea. @ 4+).

Or, the 8" price leader: 55-3231 for $7.49/$6.79 @ 4+. Use sealed isobaric in a smallish sonotube, dirt cheap and easy build.

Regards,

 

[peace brainerd]

$11.55 55-1860.................$14.99 55-1862................$17.75 55-3862

Seems like with all these low priced drivers price creep comes all too easily. For just a few bucks more it becomes.... "why not"? Unless in certain cases the less expensive driver is superior.
Is the cast basket 55-3862 a better driver for the extra $2.75?

Or, the 8" price leader: 55-3231 for $7.49/$6.79 @ 4+. Use sealed isobaric in a smallish sonotube, dirt cheap and easy build.

That's certainly an idea.

Thanks for all the input so far. I really appreciate it. I'll look more closely at all of it.

 

[bjorno]

55-1862................$17.75

Seems like with all these low priced drivers price creep comes all too easily.


[/QUOTE]

Hi,

No,I think the 55-1862 driver is a real bargain and have data you can rely on.
Why not build one or two single folded T-TQW's using 2 Drivers in parallel connected to your suggested amp.
I believe the performance would show up to be very good and IMO with a SPL capability loud enough for very pleasant listening sessions.

BTW. In the previous picture I posted I wrote: D.B. Keele JR. Optimal Closed Box...should be Opt. BR instead.

b🙂