Unity horn build

Found these snippets of info from DIY forums...so it does act as a 6th order bandpass but NOT to extend within the horn. Questions were asked about how the Danley SH50 can go down to 50hz when it`s horn mouth is so small and wouldn`t support horn loading down there. We were looking at extending our present horn out to get down to 100hz but seems we were barking up the wrong tree!

JLH ...
With the Danley Synergy horns the role of the woofers is a little different than most people think. In most of the Danley models the woofers take over from the mids at around 300Hz. They get horn loaded through entry ports just like the mids do from 300Hz down to about 135Hz. Depending on the model, 135Hz to 150Hz is all the mouth size will support for horn loading. Everything below the frequencies supported by horn loading is handled by bass reflex. In order to get the bass reflex section to match the sensitivity of the horn loaded section, the bass reflex is tuned up in frequency and made to peak in a narrow band. (When is the last time you’ve seen a pair of 12” woofers tuned to 80Hz?) So, you’re shooting for a very peaked reflex response to complement the horn loaded section. In normal life you would never design a bass reflex enclosure to behave this way because it would be a one note wonder. However, for the Synergy this is exactly what you need to extend the lower frequencies to exceed what is possible with the mouth size.

Tom Danley ...

Fwiw, the horn loading and effect of the low pass filters ends around 100Hz on an SH-50 (hard to separate it into the separate bits), the lowest part is the radiation from the ports which are short passages that extend to the rear and delay the driver’s rear signal which combined with the compliance form a stubby lumped tapped horn / vented box style acoustic phase.


So the very short tubes are just to correct the rear bass reflex path length to get that peaked response...

So back to the drawing board for us! Now we can do both parts of the driver in Hornres ...front as a standard Unity and the rear as a reflex ignoring the horn mouth...Hmmmm

.p.

I fail to see tube ports in SH46, SH64, SH69, SH96

Edited by CoblosBrengose - 11 February 2013 at 1:48am

it hadn't occurred to me that there was any horn-loading of the bass section going on. 1/4 wavelength of 150Hz is 56cm which is less than the length from bass tap to mouth. will try modelling as a ported horn (which I have designed before) and see what I get. usually in a ported horn the radiation from the two sides in inherently in phase because of the helmholtz resonator inverting the rear radiation - ports on both sides in going to screw up the crossover region. or is the port on the front of the driver tuned higher than the passband so the chamber is just acting as a LPF loading the driver into the horn and not affecting the phase???

Edited by snowflake - 11 February 2013 at 12:38pm

We  are running our Unities without any LPF on the mids with a passive crossover HPF and pad for the highs. The mids filter themselves pretty well on their own and adding a LPF seemed to screw with the phase. We got a pretty flat response and phase with a simple 2nd order crossover at 1.2k.

Gotta be someone close to you that can lend you some measurement kit...I`m interested to see how your mids work out!

.p.

done some A/B listening comparing my unity to a martin audio EM76. unity goes just as high and midrange is audibly clearer. EM76 sounds honky in comparison. going to add a couple of Beyma 10MI100 for mid-bass which should go down to 110Hz @ 108dB with 2.83V. then try and measure the impedance and design a passive crossover should be a good box for about £400 in parts

got hold of a behringer ultracurve deq2496 and condenser mic and done some measurements on the box at the top of thread. unity horn is now +/-3dB from 200Hz to 18kHz apart from one on-axis dip at 3.5kHz. off axis there is some HF roll-off and the response around crossover (1.3kHz) dips a bit.