Well, that was linked via some Oris horn related sites... And I love those amps! So elegant!
As to the dome-horn combination, here's another example -- maybe a better one:
http://www.audiodesignguide.com/my/monitor.html
As to the dome-horn combination, here's another example -- maybe a better one:
http://www.audiodesignguide.com/my/monitor.html
I have a couple of pair of "multicell" tweeters made by Pioneer. See photo below.
It's a faux multicell. The vanes are just glued into the horn and don't go all the way back. It's a small, transparent dome tweeter. Not a bad driver, decent off axis.
I may try to extend the vanes farther down into the throat of one pair to hear if it makes a diff.
It's a faux multicell. The vanes are just glued into the horn and don't go all the way back. It's a small, transparent dome tweeter. Not a bad driver, decent off axis.
I may try to extend the vanes farther down into the throat of one pair to hear if it makes a diff.
Attachments
If you want constant directivity and low higher order mode production from a dome driven horn/waveguide, you need a shallow near field waveguide of the sort described here.
http://sound.westhost.com/articles/waveguides3.htm#s7
http://sound.westhost.com/articles/waveguides3.htm#s7
this is more the way I intended it. The phase-plug we see in conus mid-drivers and in ring-radiators are different from the slitted wave-guides we see in compression-drivers. They do not fullfill the same task imho. I wonder why no 'plug' is used in compression-horns allthough beyma for instance has a td 400 and a td400/N with a little extra 'horn' in the beginning of the horn to enhance high frequencies. A multicell-horn never expands to such a hughe air volume at the mouth in every cell apart but does this by using multiples. Could it be that the hughe amount of air (the big surface ) I causing irregularities just because of the lack of horn-surface (here I mean the horn-walls)? Just trying to connect the dots between JMLC's findings about the importance of the mouth circumference and positive posts about multicells AND (call me stupid) the flow of air trough a 'spaghetti'-exhaust of a racing car: it seems to have a good influence on the opening and closing of the valves: better controlled flow, less backward pressure,.....? Crazy, perhaps? It doesn't hurt, a can assure you!
Something to do with laminar flow and chaos?
Something to do with laminar flow and chaos?
lieven said:
I spent some time with exhaust tuning as well as waveguides. The concepts are completely different. The exhaust (and intake!) lengths need to be exactly equal in length from junctions to avoid cylinder pressure pulses from different cylinders from arriving at the same time. When properly done one cylinder exit pulse actually pulls out the pulse from the next cylinder substantially reducing back pressure and increasing performance. This can ideally only be done at one RPM however.
The problem of diffraction will affect 10-15kHz region so can be neglected. Exit diameter is without tolerance and horn moulding can be +-1mm in reality so I suspect it is better make a bit smaller horn entrance and let user to sand transition by the hand? Horn model and mould is now ready.
Attachments
gedlee said:
Earl, when you were tuning exhausts, you could play with tube diameter and lenght to have high or low Q efficiency, didn't you? Peaky top performance or broader rpm-range with more average results? Isn't that the same as building a big horn vs a multicell or a 2-way high-frequency system compared to a less efficient and 'performing' 1-way system? Same goes for the number of cylinders. Torque or horse-power?
just teasing you in order to make you think, you've got the brains, I've got doubts and questions 
No, exhaust diameter was not a factor in "tuning", only in total back pressure. Much like horns, however, sharp area transitions would reflect the pulses and this could be seen in the torque curves as higher and lower torque. The idea was to minimize reflections and to time the arrivals at junctions so that the pulses had the right phases to get the peak in the torque curve where you wanted it.
On the intake, runner length was the key aspect as it would set the mass of the resonance and a large peak in the torque would occur at the resonance. Many cars had dual runners which would switch from one length to the other to tune this resonance to the RPM closest to that which the engine was operating at.
Sorry for the OT - back to your regularly scheduled channel.
On the intake, runner length was the key aspect as it would set the mass of the resonance and a large peak in the torque would occur at the resonance. Many cars had dual runners which would switch from one length to the other to tune this resonance to the RPM closest to that which the engine was operating at.
Sorry for the OT - back to your regularly scheduled channel.
jzagaja said:
Nice
I have these exit angles from Swedish supplier
It was quite a job to find it, through contact to Beyma
Others gave me angles on waveguide when asking for driver exit angles
But cudos to Jari Lønnberg for caring to find these specs
CP750Nd, 24
CP750Ti, 24.60
CP755Nd, 12.60
Seems to be the same, so ok I guess
24 degree exit angle seems a lot, but maybe due to center plug design
While Dr. Geddes post above may be off topic it is on topic to a degree I think. Some where back in the past they used the kadency effect - using stepped pipes to reflect back at the steps. This is the defraction we talk about isn't it. They were in some cases as effective as the smoother megaphones as I recall. Why it is on topic is because this is, as I understand it, the reverse of what we are trying to achieve with loudspeakers.
jamikl
jamikl
lieven said:
Most folks here seem to think that a smooth transistion is best, at least for Hi-Fi. So the mouth of the horn should have the same angle flare as the CD throat, then smoothly change to whatever the horn flair is.
It's nice to see some angles listed - thanks for the detective work guys!
Any other opinions?
Balanced Mode Radiator, "flat piston" I've got from Systemline is quite unbalanced at 3rd mode (11,5kHz). I suspect power response must be calculated because what I hear is rather smooth driver. It can be easily attached to a horn so that compression chamber forms. The idea with mass balance is to put 10-50mg at highest mode nodal line or average nodal lines for first few modes. Nodal mapping must be performed. You can also see that BMR unit from Naim Ovator changed during last month - earlier had foam damper at the center and at Munich it is absent. They still tweak the construction before serial production.
