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TH & Unity Horn - Solar sound system

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Phil B View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Phil B Quote  Post ReplyReply Direct Link To This Post Topic: TH & Unity Horn - Solar sound system
    Posted: 09 February 2012 at 11:59pm


So since moving down here to Aus I`ve been helping some mates with their 12v systems, bit different from work playing with huge PA`s!
So the plan is to make a modular , very efficient outdoor PA that runs off either a 12v battery bank or from a 24v bank with 240v invertor. The system has to travel as small as possible but then has to be big enough to cope with some big desert parties!
We have an Ultradrive ( my old one shipped over from the UK!) and are looking at these for the 24v -240v invertor system...... http://www.pascal-audio.com/amplifier-modules.html 
1 x  Pro3 module a side could run 2 or 3 TH`s easily and 2 x 700 for the Unities would be plenty. They are very efficient and small...perfect!

 I pushed them down the direction of TH`s with barn doors and Unity horns for the simple reason of efficiency and size. They were looking at Bill Fitzm LAB12 designs but I swayed them away from those as they would need a large number of boxes ( which are huge already!) and they wouldn`t have the power to run them?
We ended up with 15" Tapped Horns using 12mm ply which are small and light enough to handle on your own, then barn doors can be added for outdoor venues.  Unity horns are very, very efficient with a decent coverage and we are looking at stacking them inside each other for transport. They will be pole mounted on top of 2 horizontal TH`s with a yoke to allow them to be angled around.
So the first 15" Th`s have been built ( following the Single Sheet plan from J Bell on DIY audio) loaded with RCF 15p200`s and we sat down to measure with and without barn doors...







The blue trace is a single box on the floor, red and green are with different sized barndoors. The Blue trace of the box itself matches what has been measured before with a hump at 120hz and a dip at 170 hz ( ish) . We simply wedged old ply onto the top and sides for the door measurements but they show what happens. There`s an obvious overall gain but there`s some nice smoothing after the 120hz hump. We went all the way out to silly big extensions but the best compromise seems to be around 600mm deep , 1800mm wide and coming off the horn itself and not the end of the box.

The first two boxes having their barn doors fitted at a festival ( that`s my son inside the horns!! he loves them!)



So the system got named because of the extensions...it`s now called the " Strap-On Soundsystem" !!! Jeez some girls have filthy minds....


The Unity horns are waiting on the 5" drivers to turn up but will be a B&C De16 on the throat and will be a 60 x 60 first section flaring to a 90 x 60 second section.
After having read a mountain of white papers and articles it seems that the size , position and depth of the holes is critical to get the mids to go high enough to meet the 1" and go low enough to meet our subs. So the plan is to build a very rough prototype and then start making
different sized and positioned holes for the mid range tap, measure it and see what works!

We are still thinking about maybe making them a 3 way Unity horn by using some 10" low mids and a further tap but seeing as the TH`s go up to 250hz easily it might not be needed and we`ll see what the measurements come up with!

More to follow

.p.













Edited by Phil B - 24 October 2021 at 1:48am
Mostly harmless.... except if catering is shut.

Solar Sound System Shennanigans..http://diyhifi.biz/
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SamV View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote SamV Quote  Post ReplyReply Direct Link To This Post Posted: 10 February 2012 at 12:27am
Epic. How much are the Pascals?
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Phil B View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Phil B Quote  Post ReplyReply Direct Link To This Post Posted: 10 February 2012 at 1:14am
Still waiting on a price to get them to Aus . I`ll let ya know.

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Mostly harmless.... except if catering is shut.

Solar Sound System Shennanigans..http://diyhifi.biz/
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Phil B View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Phil B Quote  Post ReplyReply Direct Link To This Post Posted: 01 May 2012 at 2:30pm
So an update....the 2 x SS15 TH`s are complete with barn doors that clip on and off. Very neat system and all packs down to single boxes and a couple of flat sheets...

The other 2 are built and await fitting out

Here`s a photo from a little shindig in the Bush over Easter weekend. Managed to get a bit of measurement done as well ( just to annoy the relatives eh!). Amazing amount of bass/ sub for such little power. They only pulled 300w and it was more than enough!




And today we finished the first prototype unity horn. A very rough , quick build to test the new Celestion 4"`s that we picked up yesterday....literally cut/ screw/ silicon sealant!

We have started the first prototype with a 45/45 degree first section flaring out to 90 in the horizontal





And an afternoon of testing ensued...which turned into an evening and on into the night!



Notice small child....oblivious to it all!

So at the end of this marathon build / test/ re-build /re-test we have a working box that performs better than the sims. Other people have measured Unities against Hornres and Akabak and they don`t seem to quite follow the predictions. Ours certainly didn`t ! We tried shims under the mid drivers to increase the front area and it did the reverse of what Hornres said it would? BUT the main plus point is that the 4"`s go well above 1k to meet the B&C 1" so we can try different slopes and see if we can iron out the 2k bump in the B&C`s response.

Another plus point was that it was barely ticking over ( no input or output lights on the Ultradrive and 0.5v on the mid drivers ) but clearly audible from 20m and it was crystal clear even at that distance. All the talk about Unities say they have this characteristic and it`s awesome to actually hear it !

Only downside was the horizontal coverage of the 1" which sloped off dramtically after the 45 degree to 90 degree flare. Was going to happen but we didn`t expect it to be so drastic...

Next one will be 45 / 60 flaring to 90 in the horizontal ! The sims reckon we`ll loose a slight bit of gain on the mids but keep the dispersion down to the 250 hz we need.

Another day of beeps and hisses awaits .....that`ll keep the neighbours happy

.p.





Mostly harmless.... except if catering is shut.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote toastyghost Quote  Post ReplyReply Direct Link To This Post Posted: 01 May 2012 at 3:30pm
Loving the measurement mic with gas bottle stand!
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Post Options Post Options   Thanks (0) Thanks(0)   Quote davey t Quote  Post ReplyReply Direct Link To This Post Posted: 01 May 2012 at 6:04pm

You want those 4" drivers as close to the 1" as possible. I recommend replacing that thick ply you are using to mount that 1" on with a piece of 5mm aluminium. This is reduce the distance from the 1" diaphragm to the 4" exit holes. 

What size holes are you using? do you know how to work out the right delay/xover frequency to get the 1" and 4" to sum correctly? 

The 1" will have a 45 degree dispersion because it is only the first part of the horn which is loading it. The 4" mid will have a wider dispersion. 

good work!
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Teunos Quote  Post ReplyReply Direct Link To This Post Posted: 01 May 2012 at 6:22pm
If you haven't done so yet, apply a sealant or automotive grade primer to the inside of the horn, specially the throat where the HF enters the horn. This will prevent the woord from soaking up the HF and extend the response.
Best regards,
Teun.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Phil B Quote  Post ReplyReply Direct Link To This Post Posted: 01 May 2012 at 11:37pm
Originally posted by davey t davey t wrote:


You want those 4" drivers as close to the 1" as possible. I recommend replacing that thick ply you are using to mount that 1" on with a piece of 5mm aluminium. This is reduce the distance from the 1" diaphragm to the 4" exit holes. 

What size holes are you using? do you know how to work out the right delay/xover frequency to get the 1" and 4" to sum correctly? 

The 1" will have a 45 degree dispersion because it is only the first part of the horn which is loading it. The 4" mid will have a wider dispersion. 

good work!


The reason the thick ply is there is to provide a smooth transition from the 1" to the horn flare....this is what it looks like inside...




We made the horn deliberatly shorter to allow that extra wood so as to shape the horn entry point.

Yes it was correctly time delayed , we let the Ultradrive do a few auto aligns and it matched what we saw with the response, and what I guessed it would be. I didn`t have Smaart working but will get some proper phase traces at the crossover point next time.

Holes were 12mm dia in a 12mm sheet of ply. We started with 10mm holes but they seemed to cut off the lower response compared to the 12mm. The 4mm spacers were supposed to extend the top end response but in reality they made it worse? We thought maybe mounting the driver flat on the horn the cone might be touching at full excursion so maybe we`ll put in a 1mm spacer and remeasure. An alternative would be to rebate a surround cutout but it would be pretty tricky!
Also we will try some frustrum holes...like this ...



That might give us an even better upper response whilst keeping the low extension.

The traces we got from Holm Impulse were doing weird things low down. We would get different traces from either pink noise or a sine sweep? In the end we used pink noise and an rta to see which was correct and it seems the pink bursts in Holm gave a better representation of the lower end?? It`s probably Holm trying to guess the lower end, under the 150hz filter we put in.

Having 45 degree 1"s is not so bad, but for outdoors with them set maybe 3-4m apart it won`t be enough. It was an experiment with the 45 degree anyway!





Yes Mr Teunos I forgot about giving it a primer coat! It`s very rough cheap ply so would def be pretty bad for the 8k and above!

Anyway it`s a start and we won`t be making the 4 x real ones until we`ve got a response that works with a decent coverage!

.p.


( oh and Toasty that was the gas cylinder from the bar which we had drunk dry! Makes a pretty solid mic stand if a bit heavy)




Mostly harmless.... except if catering is shut.

Solar Sound System Shennanigans..http://diyhifi.biz/
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Post Options Post Options   Thanks (0) Thanks(0)   Quote slaz Quote  Post ReplyReply Direct Link To This Post Posted: 01 May 2012 at 11:55pm
Fookinell mate .... thats quite a rig you got developing there.
Not exactly "tuck it under your arm and toddle off down the road with it" style though eh ? LOL

What about powering it ? Got plenty big PV panels ?
REMEMBER....POLITICIANS AND DIAPERS SHOULD BE CHANGED OFTEN AND FOR THE SAME REASON
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Phil B Quote  Post ReplyReply Direct Link To This Post Posted: 02 May 2012 at 4:08am
Powering is via Richies fire truck at the moment ( It`s in the background in one of the above photos). He has a decent set of 12v amps and the truck has some SERIOUS batteries and panels. He has developed his set up over about 10 years but has mainly only powered 2 x small full range boxes off it plus a Cinema projector.
When we get the Pascal amps we`ll have to see how much power it draws off the wall on a set of 240v amps then get inverting to that spec! Not the most efficient way but I haven`t yet asked the Pascal lot if they can adapt any modules to 12v dc supply? Probably not but worth asking?

Next on my very full list of things to do!

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Post Options Post Options   Thanks (0) Thanks(0)   Quote davey t Quote  Post ReplyReply Direct Link To This Post Posted: 02 May 2012 at 9:20am
Yea those 4" celestions should work very well... the fs is about right and they look right. I'm not sure that your holes are big enough, most people use around 20mm diameter... 12mm sounds a little small to me

My conclusions after 2 prototypes on the unity were that a close approximation to danleys boxes can be made, however the problem is always going to be the fact that you are running that 1" compression driver right down to <1.5khz which never stood well with me. I always tried to get those mid to go as high as possible and sit as close to the 1" as possible. You can smooth the transition from round to square with a bit of filler.

Have a look at red spade audio ... he's got an interesting 90x45 design he's working on using the same mid drivers.

Keep up the good work! I wanna see some plots and xover settings next please
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Phil B Quote  Post ReplyReply Direct Link To This Post Posted: 02 May 2012 at 11:50am
Funnily enuff we bought the Celstions through a group buy organised by Mr Redspade Audio!
Been following his builds and had a few emails back and forth with him about our plans.

As for the 1" going down to 1.5khz it seems to do this quite easily? Moving the holes closer might improve the top end but we`ve already got the mids going upto 1.5 khz so we are looking at low end extension more. I`m not sure we can get higher than 1.5khz but we`ll def try a few more experiments!

We would have preferred a nicer driver like a DE25 or a BMS but everything audio in Aus is either outrageously expensive or not available here! So these drivers were scavenged from another set of boxes and the whole rig is supposed to be as much re-cycling of old materials we can get our hands on. The RCF`s for the subs were bought second hand and needed a bit of love to get in working condition.

As for lots of plots of the Unities.....well that will have to wait till we`ve got another horn built and run some comparisons ....But here`s the SS15 Tapped horn subs with and without the Barn Doors, LPF at 150hz. Bit of a difference! Really not sure what Holm is measuring low down, we think that it`s not catching the sweeps against background noise and just trying to fill in the blanks, even at quite high volumes. This is with a 40hz HPF , no idea of slope,  in built into the 12v amp ( which is going to be disabled soon)








.p.


Edited by Phil B - 02 May 2012 at 11:51am
Mostly harmless.... except if catering is shut.

Solar Sound System Shennanigans..http://diyhifi.biz/
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