Axiettes of evil
I have had some Goodman Axiette drivers for years and years with no proper boxes for them. As they only can be mounted from the rear (that came out wrong but you know what I mean).
It is a fullrange driver with high sensitivity and also quite high resonance frequency
Paramètres haut-parleur de THIELE et SMALL, sans filtre ni ampli
I have these grand plans for real Onkens for 15” drivers, but I newer seem to get to them, then I read on French site (see above) about tuning of the Axiette in a kind of undertuned bass reflex. So then it stuck me why not make the Axiettes a Onken type of enclosure and try out various ideas in a smaller scale.
So the box is made of 16mm MDF apart from the port walls that are 12mm MDF. Then I have used soft wood for braces and radiusing/ decoration
I could not get a proper tuning and at the same time get a port area equal to the cone area, so I added a 12mm radius bend in the opening of the ports as well as adding a 21 mm radius along the inner part of the ports. The ports are 16mm wide so the total surface area in the begining and end of the ports are about 176 cm2 and with a about 30 cm port lenght and a 45 Liter box the tuning is a bit above 50 Hz. Not the undertuned way of the french site but what the heck
Painting the inside of the ports was stupid as it interferes with the gluing of those small partitions strips. Next time I will use some water based dark wood stain that does not mess with the gluing. I stapled 10mm felt to some of the braces and the sides top and bottom are all lined with 10 felt. Betwen the two braces running down the back I have jammed some fistfuls of BAF.
I used a lot of bolts and captive nuts to bolt the baffle to the rest of the box. The cutout is roughly chamfered to ⅓ ro ½ of the baffle thickness, more work could be done here. I have used Neutric Speakon connector instead of the usual binding posts, I love them and will convert all my amplifers to speakon including my vintage Sansui power amplifer. I do not understand how little we have progressed on speaker connectors in 50 years. The DIN was OK for its time with low powered tube amps, then came the spring loaded terminal with its frayed cable ends and risk of shorts if the “frays” bridged plus and minus. The Binding posts of today and banana plugs of today sure offer golden bling but that is about it.
But back to the Axiette, here how it looks
It does look strange on such small stands but this is what I have.
How does it sound
Right of the bat it sound well balanced, the real bass slam is missing but everything is there in the right proportions. High sensitivty, a guesstimate is mid to high 90s for 1W. Susan Vega: Tom’s diner, sound fantastic
Duffy: Rockferry, still really good
Adele: Rolling in the deep, not to good it does not get the real weight behind it.
Kroumata Percussion Ensamble, BIS CD-232, The BIS record company have a warning label that they do not use compression at all. I have heard this particular percussion ensamble many times and I can testify that as much of the slam and impact is preserved, as far as I can judge it within the limitations of my rooms and speakers. Here it sound good but it still lack the real slam, if this is due to lack of bass or softening of midbass I do not know
Vent tuned to about 55 Hz. That 500 Hz peak is not intrinsic to the box as other drivers does not have that peak
3 cm response dip closely matches the tuning of the box, quite well balanced response, adding 50 and 100 cm show a slow decline above 2 kHz and a sharp peak at 10 kHz. I have to wait until I can measure time domain response and harmonic distortion before finding out more measurment wise.
I also measured the port output
I do not find this congruent with either the impedance dips nor the dips in amplitude of the driver output so I have yet to make head or tails out of this so any pointers is most wellcome:D
The side walls are vibrating more than I expected, when I build Onken style boxes for 15” I will make sure that they are very well braced. The axiette sound really nice if I avoid to complex music, it it is the cone that is soft and can not “slam” or if the light weight (Mms of 11 gram) cone that is more sensitive to reflections in the rellatively lightly damped cabinet I do not know. I think that the Axiettes sound better than the Lowters I have heard but they are far far behind the magic of the Voxative speakers. So a really respectable driver designed more than 50 years ago, but not a magic blast from the past. Perhaps time to use those boxes for other things...;)
Great job! A single large fullrange can be nice indeed. It slightly makes me think of these 49 liter boxes I built a while ago, in which I tried Richard Allan CG10T and Philips AD9710, as I almost went for Oken-style venting and also use bolts for the front panel.
Vent has been changed to 3" port in the back of the cab since, tuned to 40hz.
The 9710 is meant to be used facing upwards or away from the listener, remember it dates back to mono days, Facing forward the it spits and snarls in your face. Have you tried the EQ described Philips 9710/
Extension seems good on your drivers despite no whizzer.
Haven't you guys heard? You're wasting your time mucking about with vintage speakers...:rolleyes:
Love those Axiettes of Evil BTW...ditto the Philips...and Richard Allans
in my sat-horns Trumpet, Horn, Schalmei the 9710 will be lifted
below ~700 Hz, so you get the full potential of the driver but
you need a bass.
In my double horns it would play also, bass down 30 Hz, no bass impedanz
below 50 Hz 4 Ohm, for TUBES.
look SAXOPHON, POSAUNE XL, RDH20
I made LCR filter to reduce that peak at 11-12 kHz, measured the filter and it has a about 20 Ohm peak were it should. Installed it and measured frequency response before and after, no difference what so ever! It then dawned on me that a full range driver has higher than nominal impedance above 10 kHz. I measured with the driver still on the baffle, and noted that 500 Hz peak again but more pertinent to this 30-40 Ohm in the 10-20 kHz octave no wonder that the RCL filter does not do much. Adding a Zobel flattens the impedance a lot. I hope this will sort out that peak.
Here in Sweden there is plenty of 9710 around, there was a very successful company that used the 9710 and then clones and DIY versions came to the market so you often get get them on a fleamarket for very little money. In the UK it should be the Goodman and Elac fullrange drivers that are to in good supply.
Stig Carlsson of Sonab brand used 9710 as I understand. Philips themselves had DIY designs that used this driver both as front and up firing.
There was both the Carlsson Kolboxen as well as a version with a 800 Ohm version of 9710 driven by a tubeamplifer with no output transformer. We had many local companies that made loudspeaker "inspired" by Sonab loudspeakers so old 9710 and other Philips drivers are easy to come by as is Seas, Peerless and to some extent ScanSpeak and Isophon.
Well now I have listened to and measured that RCL filter along with the Zobel filter, I can not really say if it is an improvement. I now have increased the hole diameter to 190 mm and installed the Fane Studio 8M, it is a monster of a driver about 103 dB/ 1W. On this running it flat out it sound quite nice on Susan Vega and the Percussion of Kroumata is fantastic. I plan to cross it at about 4 kHz to a Beyma 21P tweeter with analog active crossover 24 dB/octave, but that will end up in other fora.
The Philips 9710 in a forward facing enclosure seemed to sound better when a slot diffuser of the Kolster/Brandes? type was placed in front of it.The Karlson enclosure does something similiar but a reflex enclosure of around 70L tuned around 40Hz(slightly below Fs) worked well with this model.
|All times are GMT. The time now is 07:47 AM.|
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2015 DragonByte Technologies Ltd.
Copyright ©1999-2015 diyAudio