hth2412 said:
The major feature of the Onken cabinet is that the port area equals the driver Sd. There are also some alignment issues, but you can Google "Onken" and do the reading. The problem with most modern drivers is that the Vas is too small to make the concept work. I have been looking specifically at the FE127E, and the required port length is 12-15" to tume to 70 Hz. This posses some difficulties with a 9.5 liter cabinet!
Bob
Greets!
Indeed! In Thuras's BR patent, which is where the original 'Onken/Ultraflex' is depicted, he states that Sd = Av was used strictly to simplify his electrical equivalent ckt. equations, but somewhere along the line it became 'gospel' as the ideal.
To keep the (13) vents short and tune it to the 12" nominal test driver's 40 Hz Fs, it had a ~15.84 ft^3 Vas, with only a 10 g Mms and a usable 50-10 kHz BW! My kind of wide BW driver.
Unfortunately, few have survived.
Anyway, folks normally either and/or just keep increasing Vb until the vent length is managable and damp them as required or use an Av = Sd * 0.75 to 0.9.
GM
Indeed! In Thuras's BR patent, which is where the original 'Onken/Ultraflex' is depicted, he states that Sd = Av was used strictly to simplify his electrical equivalent ckt. equations, but somewhere along the line it became 'gospel' as the ideal.
To keep the (13) vents short and tune it to the 12" nominal test driver's 40 Hz Fs, it had a ~15.84 ft^3 Vas, with only a 10 g Mms and a usable 50-10 kHz BW! My kind of wide BW driver.
Unfortunately, few have survived.Anyway, folks normally either and/or just keep increasing Vb until the vent length is managable and damp them as required or use an Av = Sd * 0.75 to 0.9.
GM
Thank you all, for your advise.
The idea came when I visited planet_10 (http://www.planet10-hifi.com/css.html), when using driver Adire's FS125s for mini onken. I though If possible replaced FS125s by Fostex 108 EZ.
I had already BLH so that why I want a bookshelf .
The idea came when I visited planet_10 (http://www.planet10-hifi.com/css.html), when using driver Adire's FS125s for mini onken. I though If possible replaced FS125s by Fostex 108 EZ.
I had already BLH so that why I want a bookshelf .
Hi Hai,
I've got your mail and can say that the Fe108ES plays in around 6 liters closed or 12-13 liters BR.
here is a simulation with a horn for the the fostex with my method.
length: 0,55m
throat area: 30cm²
mouth area: 60*25 cm
rear chamber: 13 liters
exponetial
in a small room? why not? could be a try worth.
cya Till
I've got your mail and can say that the Fe108ES plays in around 6 liters closed or 12-13 liters BR.
here is a simulation with a horn for the the fostex with my method.
length: 0,55m
throat area: 30cm²
mouth area: 60*25 cm
rear chamber: 13 liters
exponetial
in a small room? why not? could be a try worth.
cya Till
Attachments
Hmm, not bad. I'd be cautious though as it stands -there's a massive peak at cut-off according to your sim (what did you use BTW?), which will make for a boomy sound, especially as it's right in the zone that many recording engineers tickle up to add some extra weight. I know a small peak of 1 - 2 db isn't usually noticeable, but this as it stands breaks the limits by some margin. That impedance curve is pretty vicious too -only PP valve amps that can swing some current or one of Nelson's trans-conductance power amps need apply methinks, unless you've got a high power SS amp with a big resistor in series with the driver.
On the up side, above cut-off, it looks great -slightly decreasing response as frequency increases, which will make for a subjectively warm sort of presentation that'll be very easy to listen to over the long term, and very little ripple indeed. If you can just get rid of that large peak, I think you'd be really on to something there. Worth pursuing IMO.
Cheers
Scott
On the up side, above cut-off, it looks great -slightly decreasing response as frequency increases, which will make for a subjectively warm sort of presentation that'll be very easy to listen to over the long term, and very little ripple indeed. If you can just get rid of that large peak, I think you'd be really on to something there. Worth pursuing IMO.
Cheers
Scott
HI Scott
I've build a simular projekt with the Vifa 10BGS (you can find it here: http://www.hornlautsprecher.de/vifahorn.htm )
As you can see at the second sim we also have had a peek at the end. After we have build this horn and measured the frequenz he couldn't find/hear this peek. That is in most cases the difference between the simulation an a real projekt.
I haven't build this horn so I can't tell if it realy works. But as I know from my past projekts it could and I have a good feeling.
The impedance is like a BR.
I am using a single ended MOSfett with 15W/channel/8Ohm. Its pretty simular to the nelson pass ALEPH 0 and a NAD216. All my horns have these kind of imp. and I have never had a problem.
Maybe someone has the time and the wood to build a testbox to see if the horn worx. I haven't got a Fe108ES so I can't try it.
Till
I've build a simular projekt with the Vifa 10BGS (you can find it here: http://www.hornlautsprecher.de/vifahorn.htm )
As you can see at the second sim we also have had a peek at the end. After we have build this horn and measured the frequenz he couldn't find/hear this peek. That is in most cases the difference between the simulation an a real projekt.
I haven't build this horn so I can't tell if it realy works. But as I know from my past projekts it could and I have a good feeling.
The impedance is like a BR.
I am using a single ended MOSfett with 15W/channel/8Ohm. Its pretty simular to the nelson pass ALEPH 0 and a NAD216. All my horns have these kind of imp. and I have never had a problem.
Maybe someone has the time and the wood to build a testbox to see if the horn worx. I haven't got a Fe108ES so I can't try it.
Till
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