Audax AM21LB25ALBC 8" Paper Cone Full Range new at Madisound!!

[planet10]

A small (47 litre), short, un-braced end-loaded ML-TL, i expect much better can be done. The internal width is also narrower than i would use for an 8”, even a little wider would have beneficial impacts.

dave

 

[Tannhauser]

How about this:

Is this the design from the Rouault Acoustics website? My French is not so good, but it looks like it might have been designed by the same person who designed the driver. Can that be right?

 

[mctavish]

Yes, this is the manufacturers data sheet design. It states that bracing should be placed in two places, but for some reason it does not say that on this diagram.

Dave, if you would recommend a MLTL for this driver what would it look like?

You say wider would be better, could one just modify this design and add bracing?

 

[bobikdartanan]

50L vented box looks the best, for group delay. HF- at high inductance of the coil, not much, but maybe it sounds good.

 

[planet10]

Dave, if you would recommend a MLTL for this driver what would it look like?

Scott designs the horns & TLs, i just draw them. He has been pinged.

dave

 

[GM]

For those reading French.........

Paramètres haut-parleur de THIELE et SMALL, sans filtre ni ampli

+1, a great site I've used for ages and Google does a plenty good enough translation for those of us who only know a few popular phrases from movies.

GM

 

[vinylkid58]

Seems to model ok as a BR. A little upper bass lift. Damping in the line should knock that down.

Une ligne de transmission accidentelle.

jeff

 

[GM]

I thought it simmed great in the BR, MLTL I posted using Hornresp, but apparently not: Audax AM21LB25ALBC 8" Paper Cone Full Range new at Madisound!!

GM

 

[planet10]

~42 Hz MLTL

Vb = 91.45 L net
L = 152.4 cm/60"
Am = 600 cm^2
So = L*0.349
Ap = 214 cm^2/33.17"^2
Lp = 1.9 cm/0.75"
Po = L*0.848

QC GM?

dave

 

[Stixx]

Just stumbled across this thread...
I remember the driver from the test/feature in HobbyHifi back then...

The case that planet10 suggested looks fine to me and will boost the lower midrange some (baffle step).
So it needs to be measured again in the final case (as always) and then you can decide about the neccessary network (notch filter).

The response has quite a dip in the upper midrange that will be even deeper when you try to adjust the bump @3.5kHz that most likely will be too "hot".
But a suitable notch will take care of that and can be adjusted to your liking by changing just the resistor (within reason).
I would probably also tame the rising response at 8kHz because the 30 degree response is rising as well...

@mctavish... when you need help with your french I will be happy to assist.
Bonne continuation!

 

[mctavish]

Wow! That was fast!

Thanks Dave, GM, and everyone else.

I wont be able to buy any wood until next week, but then its on!

I will make sure to take pics of the build. I am really curious to see how this compares to the Fostex FF225k that I have now, and the Fe203en and FE206esr that I have had...

The Seas Fa22rcz that I had was also one of my Favourites.

From the build quality and features though I feel these might be better than the others. I have had them breaking in and they are very detailed and musical, not to much high frequency energy as the datasheet would suggest.

I think the key here is the dampening applied to the cone and whizzer and the phase plug. Both of which are missing on the Fostexes and the Seas.....

 

[GM]

QC GM?

Thanks! Looks fine to me except missing port offset [P0]: ~60*0.848 = ~50.88" [7/8"] down or ~9.12" [1/8"] up [i.d.].

What with all the different drivers available these days combined with folks wanting myriad HxWxD combinations, kind of surprised you don't have generic online drawings for the [3] basic [ML] TLs with A/B/C/etc., dims for us to just post a chart.

GM

 

[planet10]

GM,

Vent was in the right position, just needed to ad the dimension. The picture in the earlier post updated and this is the pdf

http://p10hifi.net/forum/GM-AudaxAM21L-MLTL-081220.pdf

You can take any of my images and tweak them, i never start from scratch, this one started out fom an earlier A12 ML-TL you did. Scott does that all the time.

dave

 

[GM]

Arg! Now that I can blow it up enough to clearly read it, the vent dia. = [214*4/pi] = ~16.51 cm/165 mm/6.5", so assume best to just list diameter for reference and show a dimensioned slot of whatever ratio ya'll normally use.

GM

 

[planet10]

The vent is derived from your A_p = 214 cm²/33.17”²

214 = πr²

so

r = sqrt(214/π) = 8.25 cm

d -> 16.5 cm

I did the arithmetic wrong the 1st time, fixed, pdf updated

dave

 

[GM]

Thanks! Know this problem well, so now rely on Google on-line calculators for math.

GM

 

[solonaika]

If I recall correctly, called it simple way to get a high quality loudspeaker. I have made a variation on Hobby Hifi's Da Capo open baffle loudspeaker, using the Ciare CH250. I do my own filter design, but I did try out the Hobby Hifi filtering.

 

[Tannhauser]

Mctavish, any update?