Desktop TL template audio discussion

[Randy Bassinga]

I am messing with a pair of pioneer 6.5 inch coaxial drivers, 90wrms rating, low 85db 1w 1 m, 32hz to 49kz for desktop monitor use. I was auditioning drivers for my car and came across these and thought wow. These had the sound that I wanted. They were mounted on a large demo board on the wall about two metres apart. I will be placing them on a 2 m wide desk

I have been wondering what kind of box would be good for these. They were meant for car door mounting, so I am thinking around 6L sealed as a start, maybe. Would anyone have any thoughts or suggestions on this?

https://www.pioneer.com.au/shop/car/ts-d65f/

 

[Galu]

Car speakers do well in large sealed boxes. 6 L would be too small, I would consider 12 L to be a minimum.

Fill the box loosely with absorbent material.

P.S. The power rating is 90 W music power nominal, probably equivalent to around 45 W RMS.

 

[Randy Bassinga]

It's rated 90wrms and 270w peak on the box and manual. Not sure how good these ratings are, though. 12 litres is achievable. A transmission line for this speaker diameter would fit in the space too, there is about 2.5m headroom above the desk surface

 

[Galu]

It's rated 90wrms and 270w peak on the box and manual.

I went by the power specs in your link.

Unfortunately, no Thiele/Small parameters are given that would help in the design of a more sophisticated enclosure.

 

[Randy Bassinga]

That's it, there aren't much in the way of specs. I suppose the only way is to try it out in some likely enclosures

 

[wchang]

I think automotive bass drivers already do 40s nearfield without assistance, so TL might not help unless you really needed desktop 35hz or lower. Elevating the driver to reduce midrange reflections yet still receive low bass desktop boost would be helpful, if you can make a 1.8-2m long 1:5 highly tapered folded line.

My two auto drivers capable of deep bass are in ~10L sealed and ~15L 0.9m pseudo-TL (ready-made "7"-shaped labyrinth).

 

[planet10]

rare in auto-kand)

It's rated 90wrms and 270w peak on the box and manual

And is absolutely meaningless. Meaningless in the real world and then multiplied by 10 or so by the auto-hifi marketers.

What kind is it? Do you have T/S (rare in auto-land)?

But they are often designed for sounding OK in a big leaky box.

dave

 

[Sonce]

I have been wondering what kind of box would be good for these. They were meant for car door mounting, so I am thinking around 6L sealed as a start, maybe. Would anyone have any thoughts or suggestions on this?

https://www.pioneer.com.au/shop/car/ts-d65f/

This is "F" version, which means it is intended for use in "Free space" - i.e. on the horizontal baffle behind the back seats. It has Qts parameter around 1. As others suggested, minimal closed box volume is 12-15 liters, well damped.
On the other hand, the "C" version (TS-DF65C) has lower Qts parameter and is intended for use in "Closed box" enclosure (or maybe in vented box).

 

[planet10]

Or use the standard aperiodic formula, build as large a box as you can live with and then make it aperiodic.

dave

 

[Randy Bassinga]

Are these ones really that bad?

And is absolutely meaningless. Meaningless in the real world and then multiplied by 10 or so by the auto-hifi marketers.

What kind is it? Do you have T/S (rare in auto-land)?

But they are often designed for sounding OK in a big leaky box.

dave

 

[Randy Bassinga]

This is "F" version, which means it is intended for use in "Free space" - i.e. on the horizontal baffle behind the back seats. It has Qts parameter around 1. As others suggested, minimal closed box volume is 12-15 liters, well damped.
On the other hand, the "C" version (TS-DF65C) has lower Qts parameter and is intended for use in "Closed box" enclosure (or maybe in vented box).

I am not able to see the same code information. As far as I can tell, the “f” is for flush mount and “c” for component

Dave
Do you think these wouldn’t be able to handle a good 90wrms and sound bad with TL or sealed to 12 odd litres?

 

[Randy Bassinga]

I think automotive bass drivers already do 40s nearfield without assistance, so TL might not help unless you really needed desktop 35hz or lower. Elevating the driver to reduce midrange reflections yet still receive low bass desktop boost would be helpful, if you can make a 1.8-2m long 1:5 highly tapered folded line.

My two auto drivers capable of deep bass are in ~10L sealed and ~15L 0.9m pseudo-TL (ready-made "7"-shaped labyrinth).

Is that 2m unfolded length? I can fold that up two or three times

 

[planet10]

I have no idea. I have heard some pretty good ones and some really bad ones. The thing is you like what they sound like.

Just trying to help you get the best out of them as you repurpose them.

dave

 

[GM]

FWIW, a neighbor got some Hertz brand speakers awhile back and the published specs were 0.6 Qt/doors, 0.75 Qt/kick panel, 0.5 Qt/woofer. Subs were the inexpensive 12" JBL/0.55 Qt sold at big box stores wih output down to ~20 Hz in room, so much lower in a vehicle's cabin gain.

 

[olsond3]

I think the man cave office needs two car door panels hanging on the wall behind the desk with the speakers mounted in them. If you want to design the speakers rather than just build them, have a look at Arta software, the Limp program is free to use. With any PC sound input/output and a small cable you can assemble and a resistor you can use Limp to measure the parameters of that woofer. The Arta / Limp manuals explain how to make the cable and make the measurements. Those parameters entered into another free program, WinISD can compute the response for different box sizes. If you go with a small box, assuming you are using a PC for the source of your music, you can you software on the PC to boost the bass a bit. equalizerAPO or JRiver can accomplish that. If you're not in a hurry you could work through some of that and do really well with those.

 

[wchang]

Is that 2m unfolded length? I can fold that up two or three times

Right, length of the line. You can experiment on any vented speaker in a few minutes with a stiff cardboard divider forced through the driver hole to make a transmission line, mass-loaded (port). Then compare before/after (L/R).

 

[Harry72]

Not long ago I measured some Pioneer Splits D series(TS-D1720c) with DATS3, from about 10 yrs ago these are classified as a 6 3/4"(although they are more akin to the current High End Z series) so will be different but it'll give you an idea of they dont like small boxes and do not model well ported(needs a large box and high tuning).
I ended up settling on 16~18l sealed playing around with WinISD 3db down at 95ish Hz and total Qtc 1.1 (critically damped), a Qtc of .707 is impossible your talking several Kl to get down in the high .8's and that wont fit the use I need in car... or in my work van I should say 🤔
They do have a Kicker 10L5 right next to them and DSP in the HU so can hopefully get away with it "somewhat I hope"
You could probably get away with OB augmented with a nice near field sealed sub crossed over high(at least 150Hz)as they do have a nice mid sound,

Qts .873
Qes 1.018
Qms 6.118
Fs 76.95Hz
Vas 10.61 L
Mms 11.3g
Le .59(@1Khz)
Re 3.26ohm
BL 4.17988Tm
Sd 140.3mm2
SPL 88.8Db

Just for a laugh I've attached some pictures of this contraption set up that's going into my work van(Im a Handyman), it fits behind the safety cage barrier and sections off the cab from the back... greatly reduces the size of the Airconditioned space(its 42°C here currently)and keeps the noise of me tools banging about at bay!
And yes reminds me of my childhood headboard on my old bed!

 

[Galu]

Or use the standard aperiodic formula, build as large a box as you can live with and then make it aperiodic.

Let's take a 15 litre (approximately 0.5 cu ft) enclosure as an example.

To convert this otherwise sealed enclosure to aperiodic loading, you can drill a 5 x 5 array of 12 mm (0.5") holes in the rear of the enclosure.

The centres of the holes shall be 20 mm (0.75") apart and be covered internally with soft, felt like cloth to provide extra acoustic resistance.

With this design, only the internal walls of the enclosure (excluding the front and back) should be lined with absorbent material.

 

[VoxCelestial]

Unfortunately, those drivers' infinite baffle performance won't translate into good sound from desktop boxes.
Car door is ~40 l leaky sealed enclosure. This kind of auto speakers have weak motor with typical Qts of 0.8-1.5 and resonance frequency of 50-70 Hz. Perfectly adequate for inteded use case, perfectly inadequate for small box.

(note the extra-wide 120 dB vertical scale)

I would suggest coaxials intended for small boxes - Tang Band W6-2313 or 2314, KEF Uni-Q (can be bought separately new or used), SB Acoustics SB16PFC25 and so on.

 

[planet10]

My thots were similar to Galu’sl, you want something somewhere between a leaky sealed box and a boffle.

And you could do a prettier pattern. I would also use a bit smaller hole.

http://p10hifi.net/tlinespeakers/forum/boffle-RadioElectronics.pdf

http://p10hifi.net/tlinespeakers/forum/Boffle-patent.pdf

dave