TS Parameters of Philips 8inch

[t.antony]

Few members have asked for the TS specs of this driver. Posting the measured parameters of the driver I have. I think this speaker is now available in the Boston acoustics catalog as model number HQ48002.


Fs = 83.86 Hz
Re = 7.10 ohms[dc]
Le = 787.75 uH
Qes = 1.46
Qms = 6.12
Qt = 1.18
Mms = 9.70 grams
Rms = 0.834214 kg/s
Cms = 0.000371 m/N
Vas = 26.88 liters
Sd= 226.98 cm^2
Bl = 4.980546 Tm
Sensitivity(2.83V/1m) = 92.80 dB


Regds...

 

[gobble]

Few members have asked for the TS specs of this driver. Posting the measured parameters of the driver I have. I think this speaker is now available in the Boston acoustics catalog as model number HQ48002.


Fs = 83.86 Hz
Re = 7.10 ohms[dc]
Le = 787.75 uH
Qes = 1.46
Qms = 6.12
Qt = 1.18
Mms = 9.70 grams
Rms = 0.834214 kg/s
Cms = 0.000371 m/N
Vas = 26.88 liters
Sd= 226.98 cm^2
Bl = 4.980546 Tm
Sensitivity(2.83V/1m) = 92.80 dB


Regds...

Thakns, I think I saw these on SP road, I was thinking of getting some drivers and place them in a rudimentary open baffle (read plank of wood) to test the first power up of amp and while I adjust biasing and listen .. os as not to damage my more expensive speakers.

How much are they? Where did you get the specs? Are there smaller 4" drivers available? These are wideband drivers right?

Cheers

Thanks

 

[t.antony]

Hi Gobble,

They are priced around Rs.250 and available at Globe Industries in SP road.

I saw another Bolton 6.5 fullrange @ around Rs.600. These full rangers (aka widebanders) could be good from 100hz to around 8khz. If you need smaller units try with the inexpensive tv speakers. Listen to them and choose the ones that sounds best

I measured the specs using the software Limp and my pc's sound card (Xonar D2X). Limp is a module in the Arta Audio Measurement and Analysis Software

Regds...

 

[biyer]

Hi Antony,

Great work.Awesome.
Have you decided on a cabinet design??
I too have the same driver..

 

[t.antony]

Hi Antony,

Great work.Awesome.
Have you decided on a cabinet design??
I too have the same driver..

Many DIY'ers are not aware of this old gem, i think this driver is capable of reproducing the lower mids (100 to 400) exceptionally good. IMO the female voice had a life like quality to it.

Planning to use them as midranges in a narrow open baffle atop my future H frames. In normal listening tests, the response above 6k seems a bit non-linear to me, these drivers need supporting tweeters crossed around 4k for full range operation. I haven't measured the frequency response yet, will update this thread once done.

Owing to the the high Qts and lower Vas, this driver could do well in a open end Transmission Line. Even though it's good for open baffle use, the low frequency reproduction is poor due to the high Fs.


Regds...

 

[t.antony]

Update...

I mailed the TS specs to a friend for simulation in Martin King's TL mathcad worksheets, the response graphs looks impressive compared to the expensive Focal 8V 4412. I am currently in the process of emulating a suitable enclosure for this driver, will post my findings.

Regds...

 

[hemantwaghe]

@ T antony ..thanks.
Ihave Philips CTN 48002 , a pair gifted by DR Jaudere..
so are these drivers same?

Any very easy to make design ( I mean a known dimensions rectangular box..)?
BTW I bough small boxes of 8 inch speakers from lamigton road and planning to test it..

 

[t.antony]

hemantwaghe,

Yes I am using the same drivers.

My goal is to get the lowest bass extension from these drivers, that's why i am opting for a TL. The quarter wave resonances in the TL will help the driver work efficiently below it's resonant frequency. AFIK for this driver the closed box is not a good option as the response will roll-off rapidly before the Fs.

However closed box might be suitable if it's intended to be used from 100hz up, crossed suitably with a sub. I haven't tried anything in that direction, but expecting this driver to be boomy in such an enclosure.​

Abhishek,

My optimism is based on the initial simulation results. If it turns out well, I will be glad to share the details with the DIY community.​

Regds...

 

[t.antony]

The only thing that doesn't look right is the high qts value. Do you think it's going to be an issue?

In the classic TL design 0.7 is considered as the maximum Qts to expect good results. I think the TL alignment tables from Martin King also had the higher limit set at 0.7. But there were people reporting success with higher Qts drivers in Diyaudio with contradictions as well as some including Martin reporting the bass on the boomy side.

Bob Brine mentions high Qts low Vas drivers suitable for TL use. As the Philips falls in this category, I did a crude test, fitted one in a cardboard box stuck to a 5 foot long pipe 5 inch in diameter. The pipe was placed on a 4' high vegetable "mesh" crate. The response didn't sound boomy to me. IMO finding the optimal cross sectional area for TL to match this driver is important for success.

Regds...

 

[vivekphadnis]

This looks like a worthwhile try. How is the build quality of the drivers?

 

[t.antony]

How is the build quality of the drivers?

Build quality is OK for a driver at this cost. You can find couple of pics of this driver here - http://www.hifivision.com/diy/10444-another-plan-open-baffles-2.html

Regds...

 

[ark]

Hi,

I picked up the other variant of this speaker, HQ48414. The power rating is 25 watt nominal/40 watt max, SPL is 93dB.

Abhishek

Hi, I purchased the same drivers from SP road. I am in the process of building a 2way speaker , mainly for testing the chip amps I am building.

Can anyone suggest a good tweeter that goes well with this driver ?

I contacted Corrson to see if they have any old stock left but unfortunately they just have one peerless woofer and few capacitors left :-(

 

[sunilraj]

The india make philips driver is pretty old in design and till retains the same. I have couple of these made in late 80's. They came with soft and very light delicate paper cone. Belive me they don't need tweeter, I run them as single driver system with a huge 350liters tightly closed enclosures. Their mid range is beautiful and plenty of tight bass.
Recently I added a bulb shaped cone plug in place of dust cap, the sound become more clear and softer. I also experiment with bullet shape, but bulb shape sound much better.
I am planning to pair this with a sub-woofer for that added punch.

Good sound may not cost $$$s

 

[biyer]

The india make philips driver is pretty old in design and till retains the same. I have couple of these made in late 80's. They came with soft and very light delicate paper cone. Belive me they don't need tweeter, I run them as single driver system with a huge 350liters tightly closed enclosures. Their mid range is beautiful and plenty of tight bass.
Recently I added a bulb shaped cone plug in place of dust cap, the sound become more clear and softer. I also experiment with bullet shape, but bulb shape sound much better.
I am planning to pair this with a sub-woofer for that added punch.

Good sound may not cost $$$s

With such huge volume Would they make good floorstanders??

 

[t.antony]

...
Recently I added a bulb shaped cone plug in place of dust cap, the sound become more clear and softer. I also experiment with bullet shape, but bulb shape sound much better.

That is an interesting tweak, have you fixed it atop the pole piece or voice coil? A picture would be helpful.

Regards.

 

[sunilraj]

With such huge volume Would they make good floorstanders??

NO, I converted the wall-Roof by partitioning the same using braced plywood.
The speakers are fixed location and cannot be moved.

 

[sunilraj]

That is an interesting tweak, have you fixed it atop the pole piece or voice coil? A picture would be helpful.

Regards.

I think if you fix the plug top voice coil, it will introduce distortion. I used a magnetised nail at the bottom of the plug and placed on the magnet pole. The nail should be fixed little off centre so that the plug will not drift when the driver is in virtical position.

I have some pics, will post soon.

 

[ark]

The india make philips driver is pretty old in design and till retains the same. I have couple of these made in late 80's. They came with soft and very light delicate paper cone. Belive me they don't need tweeter, I run them as single driver system with a huge 350liters tightly closed enclosures. Their mid range is beautiful and plenty of tight bass.
Recently I added a bulb shaped cone plug in place of dust cap, the sound become more clear and softer. I also experiment with bullet shape, but bulb shape sound much better.
I am planning to pair this with a sub-woofer for that added punch.

Good sound may not cost $$$s

Thanks Sunil.

But the damage is already done. My box is almost ready and without a tweeter it wasn't looking nice at all . I picked up an Alpine tweeter from a car audio shop.

It is a 30W RMS, 4Ohm, 88dB sensitivity unit. It comes with a built in 3.3uf cap. The freq response shows flat from 7K-20K.

Philips woofer is 8Ohm. I am thinking I will just connect them in parallel and see how it sounds. May be the extra load will compensate for lack of sensitivity of this tweeter?

 

[biyer]

NO, I converted the wall-Roof by partitioning the same using braced plywood.
The speakers are fixed location and cannot be moved.

Any suggestions for a simple box design??

 

[sunilraj]

Any suggestions for a simple box design??

The problem with this driver, it is suited only for closed box design(air tight with no leaks). The volume should be big to get good bass. Any thing around and above 60lts is good. Use narrow baffle size (9") and do listing test for best Y axis position on the baffle, You can do this by using 4-5 sectors for front baffle (do not use glue but screws to mount the same).