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 Subiectul mesajului: no compression driver?...
MesajScris: Lun Feb 27, 2006 4:02 am 
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...well, not quite like a res one. but all this talk of funktion gear did get me thinking, just how high can we go with a paper cone. whilst i was seriously talking about the prospect of no compression driver, it would be to go the way of a quality super tweeter.

consider something like a decent powerful fane or jbl bullet, pretty effortless from 6.5k up to way into the bat realms, simple fixed 40 degree conical dispersion, no hf waveguide to build and a unit physicaly small enough to be time aligned with the high mid through placement safe in the worry that it won't affect low mid horn performance. this will be cheaper and lighter than a compression driver and horn.

all you need to do is make the high mid play happily up to around 7 kHz...

james.

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 Subiectul mesajului:
MesajScris: Lun Feb 27, 2006 9:56 am 
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Membru din: Joi Oct 27, 2005 7:33 pm
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7 Khz will NOT be easy, to say the least , if not impossible with a cone driver...

do you want to go down the meaty comp driver route for the mids ?

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 Subiectul mesajului:
MesajScris: Lun Feb 27, 2006 1:02 pm 
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The 18-sound 6ND410 plays from 200 Hz~8 kHz, at 102 dB, and it's cheap too.
The powerrating is 180 Watts.

I have one as mid in my 15"wedge drummonitor, driven by a 350W/8 Chevin, and it's still working.

The 10NDA610 goes from 100 till 6100, at 103 dB, 400 Watt

It might be a nice idea

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 Subiectul mesajului:
MesajScris: Lun Feb 27, 2006 1:41 pm 
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Carl scrie:
The 18-sound 6ND410 plays from 200 Hz~8 kHz, at 102 dB, and it's cheap too.
The powerrating is 180 Watts.

I have one as mid in my 15"wedge drummonitor, driven by a 350W/8 Chevin, and it's still working.

The 10NDA610 goes from 100 till 6100, at 103 dB, 400 Watt

It might be a nice idea


those specks are for direct radiating mode

in a horn things are not the same

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ing. Mircea Bartic
Director general

Poweraudio Romania
Str. Gheorghe Sincai, Nr.26 Bistrita
Telefon: 0766332366
E-mail: office@poweraudio.ro
www.poweraudio.ro
facebook.com/poweraudio.romania


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 Subiectul mesajului:
MesajScris: Lun Feb 27, 2006 4:47 pm 
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Yes, you are right, but it "feels" to me that that only applies to the low end, or is the hi end of the freq.range also affected by a (straight) horn?
And if so, will it limit the range as a rule of thumb?

Another problem that i just thought of is the beaming.
Applying a phaseplug would offcourse remedy that, but makes the cab more difficult for those of us without a woodlathe.

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 Subiectul mesajului:
MesajScris: Lun Feb 27, 2006 5:45 pm 
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Membru din: Joi Noi 17, 2005 3:22 pm
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Unfortunately, the top end is also affected by the horn for several reasons. A horn will have better efficiency towards the low end of its tuning, and in our case where we are trying to get a controlled narrow dispersion, that means a long horn with shallow taper which will unfortunately be tuned low. An initial faster flare taper will load the top end better, but it will still be neccessary to pick a driver that has increasing sensitivity with increasing frequency, which the 6ND410 does provide.

The other problem is reflections and path length differences in the throat causing cancellations, and this is where the phase plug comes into play.

A phase plug won't neccessarily reduce beaming, and if not designed properly, can make matters worse. Beaming is determined by the width of the throat - as the frequency rises, the wavelength becomes smaller in relation to the throat width and the horn will eventually lose control of the dispersion. As we are looking at a narrow dispersion horn anyway, I don't think beaming will be a problem at any frequency we are likely to get up to.

I'm hanging out to get hold of a couple of the 6ND410s to play with, but unfortunately I am being stuffed around severely by one of my customers, and it has impacted on my relationship with my supplier....... so I can't get hold of them just yet... :x

Cheers
Graeme


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 Subiectul mesajului:
MesajScris: Lun Feb 27, 2006 6:13 pm 
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i was working on the principle that a phase plugged cone high mid would be essential to achieve this goal, a driver like the 6" neo 18sound or that trickno rcf would be a step in the right direction. it is a good deal higher than we had been thinking about going i'll admit, but if we could crack the formula there would be many benefits.

nice bullet tweeters already have the desired tight symetrical dispersion patterns built in as standard, plus they extend well up to the highest frequencies without trouble. they would have to be pretty loud, but such items exist. anyway, the main benefit would be the lack of a crossover point in critical information regions. i was playing with the crossover from my 10" mids to the 1.5" cd over the weekend and i was consistently amazed how high stuff like vocals actually goes. whilst the fundamentals are low (ish) the higher harmonics dictate the tone and timbre of voices.

to be fair, it does require higher performance from a cone high mid horn than has been achieved in diy before, make or break will be in the phase plug. dustcapectomy anyone?

james.

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 Subiectul mesajului:
MesajScris: Lun Feb 27, 2006 6:46 pm 
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Membru din: Joi Dec 29, 2005 4:04 pm
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Okay thanks Graeme,
Learned a thing or two today, although it gets difficult for me now.
You already guessed that i am not an experienced horn designer probably? :oops:

BR<

Carl

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 Subiectul mesajului:
MesajScris: Lun Feb 27, 2006 11:05 pm 
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Membru din: Mie Noi 16, 2005 7:04 pm
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Graeme,

By your site, I would say you have the most experience with phase plugs. You managed to get the Beta 8 up to 2500 and claimed you could have possibly gotten higher with additional work. You also pushed the Alpha 6 damn high with narrow dispersion.

Would it be possible for you, either hear or on your page, to offer additional detail on the throat and plug geometry for the Alpha 6? I've been working on some autocad drawings and would love to compair notes prior to starting on prototypes.

Jim


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 Subiectul mesajului:
MesajScris: Mie Mar 01, 2006 10:28 am 
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Membru din: Joi Noi 17, 2005 3:22 pm
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Jim,

Yeah, I should change and add a few things to that Phase Plugs page based on what I have observed with the Alph6 experiments, but never seem to get the time to compose something.......

The arrangement I have been using consists of the baffle hole being 110mm diameter (just slightly smaller than the outside edge of the cone), and the phase plug is 94mm diameter. The rear of the plug is machined to the same profile as the cone / dustcap, and sits about 5mm away from it. What happens after that is dependant on the flare used. So far, the horns I have been doing for the Alpha6 are designed for wide coverage, and the flare therefore initially transforms to a vertical slot. In this case, the plug is similar to that used in the JBL 2405 slot tweeter. I try to get the plug shape to give a rough exponential expansion within its length, and a flare rate a little faster than the rest of the horn.

Here is pic of the plugs:
Imagine

The wire mounts clamp between the speaker and baffle.

Cheers
Graeme


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 Subiectul mesajului:
MesajScris: Mie Mar 01, 2006 4:39 pm 
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Thanks Graeme,

Once I've had time to finish up the drawings, I'll forward a copy to you. Your input is very much valued.

I'm working with a "lesser" driver than most here would use (I got a great deal on them!), but I feel the proto types may be useful in identifing dispersion and some of the geometry.

I'll post as I proceed.

Great discussion!

Jim


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 Subiectul mesajului:
MesajScris: Sâm Apr 01, 2006 11:50 pm 
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Membru din: Vin Mar 31, 2006 12:53 pm
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Tony Andrews is able to do it because he has spent the last 40 years desperately trying to avoid using compression drivers. Additionally he has the R&D budget of FunktionOne behind him, which is quite substantial thanks to the reputation he has. Additionally he has several patents covering phase plugs that are actually attached to the magnet sructure of the cone, thus he is able to get the front chamber volume right down.

The guy is my hero, and I would love to see a DIY speaker with a paper cone all the way up to 6kHz, but I would say not possible.


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