They are about of equal importance, if you are going to compromise, do what's easiest
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OK, I answered my own question.
If I enter a big throat area into HornResp (S1=S2 for example), the cancellation occurs exactly at the 1/4 wave frequency of the section 1 length. If I use a small throat area, the the cancellation notch rises in frequency.
They are about of equal importance, if you are going to compromise, do what's easiest
Touché
The only downfall of a wider mouth is slightly more ripple in the response charateristics. But again - it's only sims, maybe real life measurements show different results.
/Thomas
Member
Joined 2003
If you're looking for "better than budget" then I guess the Pyle and Goldwood offerings are out. There really aren't any hi-end mid drivers that work that I know of. The fact that the mids are horn loaded and bandpass filtered negates the need for anything super fancy. You might look at the 5" Misco used in the original Lamda Unities. The Misco I think is this one: JC5RTF-B | Misco Speaker Company
I think weltersys has had luck with the 6" closed back Eminence Alpha, but I would think you'd need a CD that's comfortable at 1k or less.
I think weltersys has had luck with the 6" closed back Eminence Alpha, but I would think you'd need a CD that's comfortable at 1k or less.
Blatant self promotion:
My Miscos didn't sell last time around, so I re-listed them at a discount.
If you're thinking about doing a Unity horn my auction listing has the DE25 compression drivers and four of the Misco drivers which will work very nicely. You'll need to seal off the baskets but that's easy.
IMHO, the most suitable fives are the Pyle PDMR5 and the Misco sealed back unit. As noted in my last post, I have a set of four Miscos for sale on Ebay which are very similar to the units used in the Lambda Unity horn, but with the following enhancements:
1) higher motor strength
2) a hybrid neodymium-ferrite motor
It's an open-back unit tho.
Earlier in the thread, JLH noted a preference for an accordion surround, due to reliability issues with foam. The Miscos have an accordion surround; the Pyle has a foam surround.
I have used the Alpha 6 (open back) in straight conical horns with an acoustic crossover around 3500 (low crossover at 110 Hz) and the Alpha 8 on offset horns with the acoustic crossover around 1000 Hz and low crossover of 100 Hz.
Art
Since I couldn't get that Celestion 4", I went for the Misco RDC3T-A. It works damn well from what I've done with them so far. The best thing about them is that they were originally designed as a tweeter so once horn loaded they present a nearly resistive impedance. This makes it easier to use in a Synergy horn because you don't have to worry about its resonance screwing up the lower end frequency response. Its low end response is then purely controlled by the local area of expansion (i.e. local flare rate). I ordered a half case of them (30) and tested them all after breaking them in for 48 hours. Below are the overall average T/S parameters. The only way to come up with Vas was to use the sensitivity method with Smith & Larson Speaker Tester.
Fs = 1240Hz
Re = 7.76 ohms
Qes = 6.5631
Qms = 4.9345
Qts = 2.7557
Le = 0.4587 mH
Vas = 0.0559 L
Bl = 3.36
Cms = 3.36E-05
Rms = 0.77
Sd = 34.21 sq cm
Although the Misco is not available to the european consumer I'm curious of how low it will be possible to load this driver (4 units i Synergy configuration).
I realize it's possible to load below fs, but won't distortion rise significantly as you go lower?
I'm asking, because I've found a european candidate which I'll have to do some T/S measurements on:
http://www.lautsprechershop.de/pdf/ciare/ciare_ht080.pdf
Maybe JLH would be so kind and share his thoughts on this one. I would be so very greatful!
/Thomas
The special thing about the RDC3TA is it behaves in an almost purely resistive manner when horn loaded. There is no resonance peak to mess things up. The response of the RDC3TA takes on whatever the local area of expansion is. If the local area of expansion is 600Hz, then the RDC3TA plays down to 600Hz. I don't know how low it can be loaded, but 4 of them loaded down to 600Hz can drive you out of them room without a hint of audible distortion.
Thanks, John.
That is kind of the same scenario I'm hoping for with the Ciare. I'm not sure how the horn loading effects the impedance as its almost purely resisitive from specs.
I was also looking at the Visaton M10 as a candidate. I'm just not fond of the large dip (~14dB @ 700-1400Hz).
/Thomas
I have also made some decent sims with the Eminence LA-6 CBMR. The thing that worries me is that it requires fairly large entry holes to keep the compression ratio low. This could mess up the high frequency response. I'll have to make some sawdust to verify.
Also, I'm not sure if the LA-6 can make it to 1500Hz in real life.
/Thomas
Also, I'm not sure if the LA-6 can make it to 1500Hz in real life.
/Thomas
Don't be concerned. The raw response of the RDC3TA looks like crap too. However, it straightens up once horn loaded. Red trace is frequency response, blue is phase.
Attachments
Compression ratio doesn't matter. I size the entry holes to only be big enough to keep the air velocity through the port below 17 m/s at my desired SPL level. If I can achieve this with a 20:1 compression ratio, then that is what I use. Do not get hung up a certain number for your compression ratio.
Thanks again, John!
A trial:
I've made a rough HornResp model for the Eminence LA-6 CBMR with a 10:1 compression ratio - just a round number.
I'm aiming just below 120dB (one driver)
From the velocity profile, it seems that the ports can be made even smaller as the velocity does not exceed ~2.5m/s.
Any comments on this?
/Thomas
