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Advice on small loudspeakers, Sealed or Ported?
krafty
post Feb 7 2013, 20:04
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I am projecting a small pair of loudspeakers.
The use will be with a computer. Perhaps with an amp of 20W inbetween the two.

I have 2x100W 2" tweeters and 2x40W 4" car loudspeakers. Brands are good enough.
The enclosure is about 220mm (height), 142mm (width) and 143,8mm (depth).
It will be constructed with 9mm MDF.

Big question right now:

Do I go for the sealed design or do I go for the ported design?
I already know the pros and cons but I heard that some are particularly better with different kind of application.
Please answer ASAP, because I will be finishing the CAD models tonight and tomorrow I have to hand over the cabinetmaker.
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mzil
post Feb 12 2013, 21:37
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Car speakers are designed for cars.
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Arnold B. Kruege...
post Feb 13 2013, 15:33
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QUOTE (mzil @ Feb 12 2013, 15:37) *
Car speakers are designed for cars.


Not so much. Car speakers are designed to work in certain spaces with enclosures that fit into available space. The space inside a car follows the same laws of physics as any other room. The space for the enclosures is limited, but that is often the case anywhere else.

In a car there are major concerns with clearing enough free space so that speakers can operate free of obstructions, adversely reflecting nearby surfaces, and panel resonaces.

The drivers are themselves pretty conventional, often drawn from the same stocks and designs that are used for home speakers. The mounting holes may get moved around, etc. The drivers are bought in 10,000 and larger lots, so the manufacturers can be very accommodating.

Given that I live in the Detroit area and the audio community here is of a reasonable size, I have the opportunity to converse freely with many of the designers of car sound systems and their consultants. Some of these people are my closest friends. This is what they tell me. They tell me that a speaker driver is pretty much a speaker driver. Some of these people are just about the sole designers of systems that have sold 100,000s of copies with retail values up to several thousand dollars.

As a rule US manufacturers have vehicle sound quality, even for base systems, as an unusally high priority. A $50,000 car with a bad sound system is so much junk to most owners when they drive it routinely. Of course our car designers pay attention to cup holders as well. ;-)

There are a number of engineering samples that must be disposed of at the end of a project and some of them end up in personal systems. The designers whip out the Thiel/Small parameters for the driver and run some box design program and build accordingly. Sound familiar? ;-)
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mzil
post Feb 13 2013, 17:34
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QUOTE (Arnold B. Krueger @ Feb 13 2013, 10:33) *
QUOTE (mzil @ Feb 12 2013, 15:37) *
Car speakers are designed for cars.


Not so much. Car speakers are designed to work in certain spaces with enclosures that fit into available space.

Car speakers such as his, which sell for $2.15 in US dollars for TWO, are typically designed to have no specific "enclosure", at all, and work instead on the principal of infinite baffle, for example on a rear deck where the volume of air in the trunk is relatively vast [and immaterial to the driver's performance, it just needs to be isolated from the forward radiation to prevent bass cancellation] compared to the smaller ported or acoustic suspension box designs we might use in a home.

This post has been edited by mzil: Feb 13 2013, 18:30
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Arnold B. Kruege...
post Feb 14 2013, 14:54
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QUOTE (mzil @ Feb 13 2013, 11:34) *
QUOTE (Arnold B. Krueger @ Feb 13 2013, 10:33) *
QUOTE (mzil @ Feb 12 2013, 15:37) *
Car speakers are designed for cars.


Not so much. Car speakers are designed to work in certain spaces with enclosures that fit into available space.

Car speakers such as his, which sell for $2.15 in US dollars for TWO, are typically designed to have no specific "enclosure", at all, and work instead on the principal of infinite baffle, for example on a rear deck where the volume of air in the trunk is relatively vast [and immaterial to the driver's performance, it just needs to be isolated from the forward radiation to prevent bass cancellation] compared to the smaller ported or acoustic suspension box designs we might use in a home.


Most car speakers end up in the dash or the doors where the air volume is finite. The car trunk is usually reserved for the back volume of a subwoofer where again it is often not exactly infinite. It is not uncommon at all for there to be dedicated sealed volumes for car speakers.

http://a248.e.akamai.net/pix.crutchfield.c...SYS-o_spkr.jpeg
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mzil
post Feb 14 2013, 19:17
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QUOTE (Arnold B. Krueger @ Feb 14 2013, 09:54) *
Most car speakers end up in the dash or the doors where the air volume is finite.


Typical in-dash speakers optimistically work on the principle of infinite baffle, "free air", no dedicated, boxed volume of air that that act upon or "see". Designers would like to think the dash has no holes to allow the back wave from entering the cabin and canceling the front output, or in actual practice they act more like "open baffle". They are not ported nor acoustic suspension designs and there is no enclosed box structure hidden inside the dashboard; trust me. You do understand that the volume of air doesn't have to be literally infinite in order to call it an "infinite baffle design", right?

Although the volume of air in a car door is in a sense an enclosure, true, the volume of air in a typical, unmodified car door exceeds his inexpensive, 4-inch speaker's Vas, and therefore the speaker system would effectively act as an infinite baffle there as well, not acoustic suspension , nor ported. Building smaller volume enclosures into car doors for 4-inch drivers, such as his, is not common, at all, except possibly for some highly modified, competition level designs by the likes of your friend Richard Clark. Ask him.

If your knowledge of how car speakers are typically used is based on seeing his state-of-the-art, award winning work, you would have a poor understanding of how things are in the real world of consumer car audio, both factory level and typical after market upgrade level. [A field I worked in for many years, BTW.]

Subwoofers, usually trunk mounted, are the speakers in a car where one might more typically expect to see an average consumer make an enclosure/box design, sometimes using the entire trunk itself as the enclosure, such as ported or acoustic suspension, although subs are sometimes simply mounted as free air designs on the rear package tray, as well. When done this way the design is correctly called "infinite baffle", even though the volume of air is again, not infinite.

[I suspect the OP's 4 inch woofers would not work out very well as subwoofers, however, for either car or home.]

I have no idea why you included that picture of a car door speaker. If you were trying to make a point with it, please verbalize it.

This post has been edited by mzil: Feb 14 2013, 19:55
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Arnold B. Kruege...
post Feb 14 2013, 21:40
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QUOTE (mzil @ Feb 14 2013, 13:17) *
[I have no idea why you included that picture of a car door speaker. If you were trying to make a point with it, please verbalize it.


The closed mind could not see the built-in enclosures.
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Posts in this topic
- krafty   Advice on small loudspeakers   Feb 7 2013, 20:04
- - pawelq   Often different types of drivers are used in porte...   Feb 7 2013, 20:31
- - DVDdoug   If you know the Thiele-Small paramaters you can us...   Feb 7 2013, 23:34
- - krafty   Ok, thanks for answers. Well... I am not aware of...   Feb 8 2013, 00:55
|- - pawelq   QUOTE (krafty @ Feb 7 2013, 18:55) The sp...   Feb 8 2013, 15:57
- - krafty   I get what you mean about not knowing RAM Bus, CAS...   Feb 8 2013, 16:35
|- - pawelq   One more observation (not that there aren't mo...   Feb 9 2013, 19:20
- - krafty   Ok, I realized I just overlooked some of the thing...   Feb 8 2013, 20:06
- - krafty   Well, about sealing and ported, I gave up. The woo...   Feb 10 2013, 01:15
|- - pawelq   The capacitor will serve as a simple high-pass fil...   Feb 10 2013, 04:32
- - krafty   Ok, so I have here the 2-way crossover calculator....   Feb 10 2013, 06:45
|- - pawelq   QUOTE (krafty @ Feb 10 2013, 00:45) Ok, s...   Feb 10 2013, 08:34
- - krafty   QUOTE Obviously it has to be in the drivers' o...   Feb 11 2013, 03:10
|- - pawelq   QUOTE (krafty @ Feb 10 2013, 21:10) I rea...   Feb 11 2013, 16:44
- - krafty   pawelq, thanks for all the info. Yes, it can be tr...   Feb 11 2013, 19:34
- - krafty   pawelq, Please take a look at values for my midra...   Feb 11 2013, 23:54
- - krafty   I am playing around with WinISD, and soon I will p...   Feb 12 2013, 01:47
- - Arnold B. Krueger   QUOTE (krafty @ Feb 7 2013, 14:04) I am p...   Feb 12 2013, 15:32
- - krafty   Yes, I have been there already and am running a to...   Feb 12 2013, 18:19
- - mzil   Sealed. The fact that you have to ask the questio...   Feb 12 2013, 19:20
- - krafty   mzil, I was playing with WinISD beta, and I enter...   Feb 12 2013, 20:07
- - krafty   First of all, I would like to thank the folks who ...   Feb 12 2013, 21:03
|- - julf   QUOTE (krafty @ Feb 12 2013, 21:03) I sti...   Feb 12 2013, 21:27
- - mzil   Car speakers are designed for cars.   Feb 12 2013, 21:37
|- - Arnold B. Krueger   QUOTE (mzil @ Feb 12 2013, 15:37) Car spe...   Feb 13 2013, 15:33
|- - mzil   QUOTE (Arnold B. Krueger @ Feb 13 2013, 10...   Feb 13 2013, 17:34
|- - Arnold B. Krueger   QUOTE (mzil @ Feb 13 2013, 11:34) QUOTE (...   Feb 14 2013, 14:54
|- - mzil   QUOTE (Arnold B. Krueger @ Feb 14 2013, 09...   Feb 14 2013, 19:17
|- - Arnold B. Krueger   QUOTE (mzil @ Feb 14 2013, 13:17) [I have...   Feb 14 2013, 21:40
- - krafty   QUOTE f not, you will probably have a problem with...   Feb 12 2013, 23:07
- - krafty   I am doing a port on the front of the box, below t...   Feb 13 2013, 23:06
- - krafty   I am doing a port on the front of the box, below t...   Feb 13 2013, 23:10
- - krafty   Hey guys. I have received a notice from the wood ...   Feb 14 2013, 16:07
- - mzil   QUOTE (Arnold B. Krueger @ Feb 14 2013, 09...   Feb 14 2013, 23:51


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