2-way Unity horn 250hz-20khz |
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snowflake
Old Croc Joined: 29 December 2004 Location: Bristol Status: Offline Points: 3118 |
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this all rather depends on what mids you use and what impedance you make for the mid section but: if you end up padding down your tweeter you can put a bypass cap on the series resistor of the L-pad and effectively put in a high shelf equivalent to the gain reduction that the pad puts on the the tweeter. this will then dictate which tweeter you choose and how much HF roll-off it has.
I'm not sure what T.D. means about a paralell inductor in that diyaudio thread so maybe there is a completely different way to go about this. |
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fatfreddiescat
Young Croc Joined: 15 October 2010 Location: N.E.Wales Status: Offline Points: 1081 |
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My take on it is that the inductor is pat of the highpass filter, by being directly connected across the driver terminals it effectively shorts the driver out at low frequencies, hence damping any diaphragm movement caused by the other drivers in the waveguide. With a capacitor in series the driver is effectively decoupled from the amp.
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citizensc
Young Croc Joined: 16 October 2015 Location: Perth,Australia Status: Offline Points: 532 |
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By this do you just mean the simple Le value in mH as published on the B&C website? Or the Klippel model which includes Le2 and Re2? I understand that inductance impacts on the HF response of a driver, even in the context of subwoofers (look at the B&C DS series drivers) but this cant be the sole determinant of HF response in a compression driver can it? Not with how many other variables there are? Do we not have to take phase plug geometry, compression ratio, reflectors, diaphragm material, diaphragm geometry among other things in to account as well? With regards to passive crossovers, right now my focus is to get the horn to work acoustically and just use DSP (Linea ASC48). Once I have figured that part out, I may attempt to build a passive xover. |
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snowflake
Old Croc Joined: 29 December 2004 Location: Bristol Status: Offline Points: 3118 |
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so you can make a first order filter like this with just an indcutor in parallel (though even with an L-pad it's going to draw significant power out of passband). but isn't this also true of all even-order passive filters? - the Le is paralell with the driver will short at low frequencies and damp the tweeter with back-EMF. |
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fatfreddiescat
Young Croc Joined: 15 October 2010 Location: N.E.Wales Status: Offline Points: 1081 |
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Exactly that, though the inductor wouldn't necessarily be directly accross the driver in the case of a 3rd order filter or if followed by an L pad etc. If the driver were to be connected directly to the outputs of an amp then then the amps damping factor will do the job.
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fatfreddiescat
Young Croc Joined: 15 October 2010 Location: N.E.Wales Status: Offline Points: 1081 |
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PS would love to come and have a listen to ur sounds when all this lockdown malarkey has passed, we were planning on doing a night in Bristol with my system this year until it turned into a washout.
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snowflake
Old Croc Joined: 29 December 2004 Location: Bristol Status: Offline Points: 3118 |
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yes, definitely let me know if you are ever down here. Would be nice to get all the gear out the lockup. It's strange this unity horn stuff - even though I've managed to build some that seem to work pretty well, I still don't think I understand a lot of what is going on! been thinking about what Danley says about caps in series and inductors in parallel. Does that imply that if you put a DC blocking cap in series with a driver you reduce the damping factor to almost zero at low frequencies? |
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fatfreddiescat
Young Croc Joined: 15 October 2010 Location: N.E.Wales Status: Offline Points: 1081 |
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Yes, a dc blocking cap does just that, as to whether it is a problem or not is another matter, I guess when you have the mids and lows sharing a waveguide, the pressure at low frequencies will be higher so more potential for issues, think Dave Rat came to the same conclusion when he was loosing hf drivers on cabs that were not plugged in but close to others that were. Do give me a shout when you do have something planned, my brother is in Bristol, used to make visuals for the recursive dome and also my son has another year at uni there.
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Elliot Thompson
Old Croc Joined: 02 April 2004 Location: United States Status: Offline Points: 5172 |
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The simple Le value has been the standard for decades and, you should use that for reference when comparing various drivers than Klippel. The reason is, not every manufacture follows the Klippel topology which, can lead to assumptions that may not be correct when comparing various drivers.
A compression driver is a loudspeaker so, it is not an exception to Le. There is a co-relation between the Le and the impedance load at the given frequencies above 10 kHz for high frequency components.
The Horn does play a factor on the impedance curve. However, like cone speakers, compression drivers are generally measured in free air. This eliminates any limitation or escalation from the horn deducting/contributing to the compression driver's frequency response. Compression drivers usually offer a very smooth response. However, things will become more jagged when placed in a horn.
If the manufacture did not specify a particular horn on the
advertised compression driver charts, one should not assume the driver was
measured on a horn. It would be best to contact the manufacture to confirm your
assumptions. Best Regards, |
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Elliot Thompson
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Phil B
Old Croc Joined: 21 November 2004 Location: Melbourne Status: Offline Points: 2322 |
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Just to go back a bit...
Did you look at the Syntripp when you were thinking of your original plan? https://www.diyaudio.com/forums/multi-way/264485-syntripp-2-2-virtual-single-source-horn.html We built a pair for an install here in Melb with B&C drivers about 5 years ago and they perform really well. With more modern Neo drivers they would be very light weight? There's loads of info in that thread as well.. As you were... .p. |
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BigSoundNorthWest
Registered User Joined: 29 November 2014 Location: Manchester Status: Offline Points: 290 |
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Hello,
extremely nice to see you back on SP Kyle :) |
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citizensc
Young Croc Joined: 16 October 2015 Location: Perth,Australia Status: Offline Points: 532 |
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I have looked at a lot of different projects but not the Syntripp, it looks interesting, I like the idea of being able to separate it in to two parts. It is how ever a different set of compromises to what I am aiming for. I hope for much higher sensitivity and do not need an f3 that low. The other thing is I want this system to be purely 'me'. All my designs, something I can be proud of. While I would like the system to pay for its self at some point, one of the main reasons for the project is to challenge my self.
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