Measuring speaker cone diameter-is 6.5inch equal to 5.5 inch

[rpanand25]

I got Infinity P 163 bookshelf from US recently. Somebody bought from Harman directly and brought it. The measurement of mid woofer is advertised as 6.5 inch. when i measured the diameter it measured 5.5.inch. :sad:
Can someone explain where the one inch has gone? are they taking into account some hidden cone area?
Amazon.com: Infinity Primus Two-way 6 1/2-Inch Bookshelf/Satellite Speaker (Black, Each): Electronics
i have attached image

i have measured from outer of surround on either side

 

[rpanand25]

perhaps i should measure as a curved surface using a thread then measure on tape the curved surface length thus accounting for the extra inch.

 

[mpw]

Generally it is outer to outer and that includes the woofer frame on which it is bolted to the front baffle

 

[Fantastic]

This is a gray area.
The speaker size mentioned in print is usually the 'outer' size of the driver frame. But many drivers have strange frames and the 'outer' location could be any point on the frame that they choose !
The actual size that is used for measurement and as a physical parameter is typically from the middle of the surround on one side to the middle of the surround on the other side. This makes it just slightly larger than the physical 'cone' . The surround being the flexible part of the driver between cone and the metal ( or plastic !) frame.
So measure the diameter of the actual cone and add the width of the surround ( on one side).
So , yes, some 'large drivers' actually have smaller effective cones ! Nothing you can do about it ! Is it a con?... sure ! But that's how it has been done all these years .
This should also make it clear that not all 6.5 inch drivers have 6.5 inch cones and even between themselves there are bigger and smaller cones ....so they are all not equal performers ! Typically the ones that are mid/woofers have much wider surrounds and so 'much smaller' effective cones.
Applies to drivers of any size !
Now go get yourself a drink and drown your sorrows !

 

[rpanand25]

This is a gray area.
The speaker size mentioned in print is usually the 'outer' size of the driver frame. But many drivers have strange frames and the 'outer' location could be any point on the frame that they choose !
The actual size that is used for measurement and as a physical parameter is typically from the middle of the surround on one side to the middle of the surround on the other side. This makes it just slightly larger than the physical 'cone' . The surround being the flexible part of the driver between cone and the metal ( or plastic !) frame.
So measure the diameter of the actual cone and add the width of the surround ( on one side).
So , yes, some 'large drivers' actually have smaller effective cones ! Nothing you can do about it ! Is it a con?... sure ! But that's how it has been done all these years .
This should also make it clear that not all 6.5 inch drivers have 6.5 inch cones and even between themselves there are bigger and smaller cones ....so they are all not equal performers ! Typically the ones that are mid/woofers have much wider surrounds and so 'much smaller' effective cones.
Applies to drivers of any size !
Now go get yourself a drink and drown your sorrows !

If this is so then why nobody takes up standardisation of cone size measurement . This also becomes like rms,peak power,program power at various frequency ranges, at various distortion levels etc leaving the field wide open for marketing whiz kids and leaving us more confused and cheated

 

[mpw]

which is why you need a :cheers:

so leave the measuring tape alone and judge by your ear only.

what are you going to pair these with ?

they are good looking speakers and quite low on price too.

rgds

 

[htfan17]

Its the same as TV screen sizes buddy. A 32 inch will never be 32 inch screen...always lesser.

 

[Hiten]

Hello rpanand,
Most bookshelf have around 5.5 inch driver. In my opinion If you think positively these drivers should image well compared to larger driver. I have heard some bookshelf studio monitors with 8 inch driver and a tweeter. I didn't like the sound. I am presuming that with specification in mind you opted for a little larger driver to get little more low end extension. But again in my personal opinion it would not make significant difference. If you want proper full range sound you will need to add a subwoofer regardless of 1 inch difference. Other option I guess is if you place speakers in a corner or near wall you can get little more bass sacrificing minor low end quality. All these differences are subtle to be easily identified. That way I feel my self lucky if you know what I mean. As Fantastic and mpw has said don't worry enjoy your new speakers.
Regards.

 

[rpanand25]

Thanks all of you for sharing in my ONE INCH SORROW:lol::lol::lol:
I know infinity primus has P143 and P 153 bookshelf with 4 inch and 5.25 inch bookshelves and i assume they would measure short.

Yes I bought these as an economy offerings and did not expect rated bass response of 49Hz presumably at +-3db as I had read reviews. what i know was that have some sparkle at top end, image very well, built like a tank(for the price), have a proper cross over and stiff cone/surround to emphasize on mid frequencies despite rated low frequency response and have a long break in period of 100 hrs plus.

I donot have a proper amp as such and was toying with all T amps etc but wanted to go for regular integrated. Presently i am using as a satellite to my F&D F 690U and Intex 2600 blaster computer multimedia speakers turn by turn. This is because Intex lets me turn down the bass all the way down and hear only the infinitys.The F&D has residual bass even if it is turned all the way down thus allowing sub to function. But the surprise is that without any sub crossovers the sound is very pleasant and the infinitys seem to unravel congested tracks well considering that i am predominantly using mp3 tracks alongwith some FLACs through computer 3.5 mm out. I would like more body to the mids but given my source material and the new drivers, it is expected.

Yes I am looking for integrated till such time i get Emotiva etc when somebody comes from US. I missed the marantz 6004 sale in hi fi mart. A pre owned one can also do till that time and am looking at various offerings.

I find them good looking and weighty at 7.5 kgs. each. Fit and Finish is very good at the price point. I hope they also hit at least 55 Hz despite some reports to the contrary.
Lastly I am thinking of taking up with Harman to get their feedback. i donot expect much but still it is required.

 

[shkumar4963]

OP. You are measuring it correctly.

 

[rpanand25]

The following reply I got from Harman is quoted below



"
From: HCG Customer Support 5 <[email protected]>
Date: Fri, May 29, 2015 at 12:38 PM
Subject: RE: Harman International Case # 00382213: Infinity Primus Bookshelf Speaker Complaint ref:_00Di0fiJD [ ref:_00Di0fiJD._500i0PmE99:ref ]



Hello,

This is a 6.5. You cannot measure the actual woofer. The whole speaker has to be measured from the basket which is the entire diameter of speaker the metal part.

Thank you,
Starr Thompson
Harman International
Level 3 Technical Support
"

 

[Sumanta]

Is diameter of a driver used in any speaker design calculation considering T/S parameters? That's why manufacturers use their own "standard" methodology. What shall be diameter of an oval driver then?

 

[Srinath_seshadri]

Infinity's 6.5 is almost to the outside of the frame, which is covered up by your plastic silver trim piece.
I've measured speakers that are spec-ed as a 12 to over 13". Those JBL LE 140's are that way.
Cool.
Srinath.

 

[GeorgeO]

I guess these guys are selling speaker size like the real estate companies sell their flats by "super built up area".

 

[sunilkm]

Infinity's 6.5 is almost to the outside of the frame, which is covered up by your plastic silver trim piece.
I've measured speakers that are spec-ed as a 12 to over 13". Those JBL LE 140's are that way.
Cool.
Srinath.

My understanding was that the diameter value specified is including the rubber part around the cone.

Is the plastic/fancy/ any other trim around is also included in the dia? If yes, then it is difficult to understand the cone size and actual cone dia

 

[Srinath_seshadri]

Usually the outer of the surround is about 1/4-1/2" under the speaker size.
And yes, the real estate analogy applies ...
My house is 2800 sqft ... no its not, it was speced to be 2723 by the builder. We didn't install 2 optional walls. So we get like 10 sqft more. So, no not 2800.

Infinity is notorious for rounding up to the nearest profitable number by the advertising manager. Sorta like HP ratings from cars or motorcycles ... you see we have this car with 400 horse power, but these horses have been through a famine and can barely stand up.

Is the plastic/fancy/ any other trim around is also included in the dia? If yes, then it is difficult to understand the cone size and actual cone dia

You're over thinking this. There is a 1/2-3/4 inch of speaker frame and surround, screws etc etc under the plastic, all that is added to the number. If you want to be happier you can say you have a 6.2165" cone. Or just follow infinty's idea and go with 6.5.

Cool.
Srinath.

 

[alpha1]

All the more reason to follow the maxim:
Performance counts, not the specifications.