DATS V2 and Infinity PS 10 Driver

[Alex2507]

I used the DATS to get free air measurements and a Vas value. Plus the impedance and phase showed nup. I don't know how to get the images here but printer, camera and photobucket get me this:

Holy smokes, photobucket doesn't want to cooperate but I waited it out.

Here:






Obviously I'm fumbling pretty bad so 'how to' on sharing images etc would be good. The plate amp had a melt down on a spot too tight to solder up/jump so an external amp got wired up. That needed EQing real bad and now the EQ is crapping out. It was a major pain to set up with REW and measurements, etc. Now I have a toy and the T/S parameters. I need help modeling this driver. It comes in a box that has a 3"x10" port fluted on both sides and a plate amp that could be removed for a gain of 0.18'^3 on what is an existing Vb of 1.1'^3 box. It had a terrible 60 Hz peak.

Anyway there it is.

 

[its phillip]

Use imgur for hosting images

 

[everettT]

How did you get VAS, in an baffle or with weight added?

 

[Verdinut]

I used the DATS to get free air measurements and a Vas value. Plus the impedance and phase showed nup. I don't know how to get the images here but printer, camera and photobucket get me this:

Holy smokes, photobucket doesn't want to cooperate but I waited it out.

Here:






Obviously I'm fumbling pretty bad so 'how to' on sharing images etc would be good. The plate amp had a melt down on a spot too tight to solder up/jump so an external amp got wired up. That needed EQing real bad and now the EQ is crapping out. It was a major pain to set up with REW and measurements, etc. Now I have a toy and the T/S parameters. I need help modeling this driver. It comes in a box that has a 3"x10" port fluted on both sides and a plate amp that could be removed for a gain of 0.18'^3 on what is an existing Vb of 1.1'^3 box. It had a terrible 60 Hz peak.

Anyway there it is.

Alex,

It's a ported box and in this situation, you should have two impedance peaks. The impedance curve only shows the upper frequency peak but you can get DATS to show a frequency range that goes down to 5 Hz where you would see the lower impedance peak as well.

Cheers,

 

[Alex2507]

How did you get VAS, in an baffle or with weight added?

added weight

Alex,

It's a ported box and in this situation, you should have two impedance peaks. The impedance curve only shows the upper frequency peak but you can get DATS to show a frequency range that goes down to 5 Hz where you would see the lower impedance peak as well.

Cheers,

In the cabinet I got two peaks but free air only got me one. I'll lower the Hz and try again tonight. Thanks.

 

[Alex2507]

Alex,

It's a ported box and in this situation, you should have two impedance peaks. The impedance curve only shows the upper frequency peak but you can get DATS to show a frequency range that goes down to 5 Hz where you would see the lower impedance peak as well.

Cheers,

Yup, free air only gets me one impedance peak. In cabinet gets two. Still looking for an 'optimal' box/port size as I suspect Infinity might have chosen to have the 60 Hz bloat to fool the Bose crowd.

 

[Verdinut]

Yup, free air only gets me one impedance peak. In cabinet gets two. Still looking for an 'optimal' box/port size as I suspect Infinity might have chosen to have the 60 Hz bloat to fool the Bose crowd.

This driver has a Qts of 0.65 and is not designed to work in a ported box. It is a perfect match for the sealed cabinet which Infinity supplies with it.

 

[Alex2507]

This driver has a Qts of 0.65 and is not designed to work in a ported box. It is a perfect match for the sealed cabinet which Infinity supplies with it.

This driver has a Qts of 0.65 and is not designed to work in a ported box. It is a perfect match for the sealed cabinet which Infinity supplies with it.

It was sold in a ported box. What makes you think a PS 10 is a sealed sub?

 

[Verdinut]

It was sold in a ported box. What makes you think a PS 10 is a sealed sub?

I just mentioned above that a woofer or a subwoofer with a high Qts of 0.65 is not suitable for a ported box. I built several ported cabinets over many years and I know the mechanics of drivers and how to analyze speaker specs.

Ask anyone who is knowledgeable about speaker specs and builing speaker enclosures who will confirm my opinion.

 

[Alex2507]

I just mentioned above that a woofer or a subwoofer with a high Qts of 0.65 is not suitable for a ported box. I built several ported cabinets over many years and I know the mechanics of drivers and how to analyze speaker specs.

Ask anyone who is knowledgeable about speaker specs and builing speaker enclosures who will confirm my opinion.

I believe you, there's a misunderstanding.

It is a perfect match for the sealed cabinet which Infinity supplies with it.

Infinity did not supply a sealed cabinet with this driver as you seem to be saying.

 

[Verdinut]

I checked on the web and that PS10 sub comes with a ported box as you confirmed.

I've just verified with the BassBox 6 PRO software with the specs that you provided for the driver. BassBox indicates that the EBP (Efficiency Banwith Product) of the driver is 45 and it would usually be best suited for a closed box. It recommends a 1.5 cubic foot closed box which would provide an F3 at 43 Hz. which could be EQ'd to obtain better low frequency response.

There are exceptions for some designs and this driver seems to behave rather well in a small ported box. This however does not exclude that it would perform badly in the 1.5 cf sealed box.

 

[Alex2507]

this driver seems to behave rather well in a small ported box.

Would you mind running the numbers through Bass Box and telling me what they come up with for Vb and port size?

I can get 1.28 cubic feet pretty easy with the existing box by removing the plate amp and making the port external. Actually the question here is what port size would I need with a 1.28 cubic foot box?

 

[Verdinut]

Alex,
It's not that I don't agree to run the BassBox software per your request. I'm having problems with the software, some of the functions don't work as designed.
I uninstalled and reinstalled the software but there are still some bugs. I will have to try to contact Harris Technologies for resolving the problem.
Perhaps, if you knew another member who has access to BassBox software, you could get a faster answer. Otherwise, I'll get back to you as soon as I get help from the supplier of the software. Sorry about the inconvenience.

If you just want to put the duct outside the cabinet, if there's an existing duct as I assume, I would just try by reducing the length of the duct a little bit. For example, if it's 10 inches long, I would just shorten it by 1½ inch or so. But, you will not get much of a noticeable improvement by putting the ducted port out of the box. However, if you doubled the internal box volume, then you would get more LF extension but at the expense of reduced transient response due to the high Qts of the driver. There are always compromises involved in the design of woofer or subwoofer enclosures.

 

[Verdinut]

Yup, free air only gets me one impedance peak. In cabinet gets two. Still looking for an 'optimal' box/port size as I suspect Infinity might have chosen to have the 60 Hz bloat to fool the Bose crowd.

For your information, if you run the DATS software with the sub as installed in the ported box, the lowest impedance figure between the two peaks is the box tuned frequency.

 

[Alex2507]

I just checked over at PETT and found some settings I needed to adjust so my numbers might not be right. Volume settings and format weren't maxed out or set for CD. The education continues.

If a mod spots this deleting the thread might be best to avoid people wasting time until I get my ducks in a row.

Thanks.

 

[Alex2507]

the lowest impedance figure between the two peaks is the box tuned frequency.

That's 39 Hz. The two peaks are 18 Ohms at 22 Hz and 60 Hz in box.

The RBH I replaced the Infinities with has a 26 Hz low point and the first peak is 8.5 Ohms at 16 Hz. The second peak is 14 Ohms at 48 Hz.

 

[Alex2507]

Okay. Here are some tips for future Alex: It's real important to keep the speakers and mic on the USB Audio Codec set at 100 and to keep the speaker properties under the advanced tab set to CD quality 16 bit/44100 Hz ... and you have to hit Apply and OK.

The last round of #'s came from dvd quality.

 

[Alex2507]

Playing around with the DATS V2 and things I do understand to some degree, I compared the Q of the sub with the amp housing installed the normal way and this way:



The Q shot up from around 1 to around 1.4. Wrong way. I assume stuffing the enclosure to tie up space would make it go the right way.

The User's guide has a thing on designing Zobel Network. That's cool. A minute ago I didn't know what that was. Learning is hard.

 

[Swerd]

The User's guide has a thing on designing Zobel Network. That's cool. A minute ago I didn't know what that was. Learning is hard.

Zobel networks, if I understand them correctly, are rarely needed in home audio when solid state amplification and properly designed 2-way or 3-way speakers are used. Apparently, they were used more often in the past with vacuum tube amps.

Is your post about a sub woofer? If a low-pass filter is used somewhere around 100 Hz or lower, why use a Zobel? The low-pass filter should keep the driver well below any frequency where a Zobel circuit might work to keep the impedance from rising. I didn't read the whole thread and may have missed something mentioned earlier that explained this.

Zobel networks were invented in 1923 and were widely used in telecommunications over long copper wire land lines.
Zobel networks as used in home audio.

 

[Verdinut]

IMO, Zobel networks (for impedance compensation) should be used when designing passive crossovers on all drivers that show a significant increase in impedance with rising frequency.

From a reliable source, I was told that Dynaudio may not still be doing it, but they used to implement Zobel networks on all their drivers, even on some tweeters if it improved performance.

There's a good article from Rod Elliott (Elliott Sound Products) relating to passive crossovers and Zobel networks:

http://sound.whsites.net/lr-passive.htm#s3.1