1x18 Horn

Here's some pictures for everyone to have a look at.


First here is three horns. Green plot is 1850. Blue plot is my new horn.
Red plot is the WSX. WSX plot is the horn translated to a cabinet width of 600mm.





The new cabinet plotted as a pair.





This is the first prototype. The mk2 has changed slightly, and still needs a bit of work to make it even easier to make, but the horn will not be changed much, if any.


In all the rest of these plots, the drivers used for comparison purposes are a Void V18-1000 and
a Celestion FTR18-4080-HDX. If you have your doubts, and think the sensitivity is too low for it to do what is shown, then I had the same opinion, and dismissed it from consideration at first. I can say now that when placed in this new horn, except for two points at 60 hz and 110 hz where they are equal, the Celestion is louder at all other frequencies up to 120hz, than the void in an 1850 horn, and at some points, up to 3db louder, when compared watt for watt. Some of you will no doubt be saying that it must sound really muddy or woolly. Well it doesn't!. It sounds only slightly warmer than the void, which does sound 'hard', and it also has a bit more depth to the lower frequencies. You can't tell the difference between the void in an 1850 and the Celestion in the new horn, it's just as punchy, and dynamic, and except for the deeper, lower frequencies giving it more depth, they sound and play the same.


So here goes with some plots. Hornresp does show the Void as peaking a bit too much at 60 hz. Also the trough is not as pronounced as shown. It starts at 70 hz and is about 3db down at 80 hz, but back up and going higher than the 70 hz level, at 90 hz. The peaks at 120hz and upwards for both drivers are not as great as shown. I have measured this. The Celestion stays flat from 70 to 120 hz, the Void is only ever at this same level at 110 hz and at the peak at 60hz. So a bit of interpretation of the plots has to be done, especially at the 60 hz and 120hz upward areas. Having driven this driver alongside a void, I have no hesitation in saying it is an equal when used in the correct horn, up to 800 watts or over. I have yet to be able to drive it past xmax, when using music, as opposed to sine wave input, and this has been in excess of 800 watts rms. I have also included some comparisons between this and the C18-650el, but I think with a 1000 watt voicecoil and a higher xmax, the celestion has the better chance of surviving the punishment.


All horns have been plotted in half space.


Parameters for single cabinet.





Parameters for group of 4.





Here's a plot of the new horn against the 1850 and wsx. All single cabinets. Red WSX, Blue 1850,Green HDX.





Here's a plot of 4 cabs combined, Red WSX, Blue 1850, Green HDX





This is a plot at 3200 watts into 8, series parallel.


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This is a comparison of the HDX and a C18650el in a 186 horn. Red is C18, green is HDX





Comparison of HDX and C18 in the new horn. Single and multiple of 4.





Comparison of HDX and C18 in WSX, single and multiple of 4.





So what does everyone make of this?. Any good?. I am not making any claims for a far better cabinet than anything else, just that it is a viable alternative that may offer a slightly lower extension on the bottom end.


One thing is for sure, and that is the driver has to be considered when using a horn with a larger rear chamber. I was at first comparing this with the PD186, and more recently with the C18650el. I think that the Celestion has the edge when considering power handling and durability.
Cost of driver at normal prices is slightly higher than the C18, about £10, however if anyone would be interested in a group buy, the Celestion would be £107. See the for sale section.


Cabinets. The WSX weighs in at the top and is 572 litres external volume. Next is my new horn at 513 litres, but if using the HDX, weighs about the same as the 1850 when using a void. 1850 is 456 litres.
Weighs in at about 85 kilos with the Void.
Both the 1850 and the HDX horn use about the same amount of ply, I know I can get one out of less than two sheets. So cost wise I think that the new cabinet is fairly competitive. Especially when taking the driver into account. Ease of build is the next factor, and by the time I've got the final design done, it will be as simple as possible.
As a conclusion, I think here is a viable and cheaper alternative, especially for the less experienced builder. I'm going to be making a fair amount of these cabinets, because a few of the locals have shown a keen interest. So I might be able to arrange for a bulk build, again if anyone is interested, and is not confident enough to build their own, and the price is around £170 for the fully made up carcass.
Final plans will be published soon, but there will be a few changes to the cabinet that is depicted above. The front is a bit wider, and the access hatch is on the side of the chamber, not on the top as shown. Top and side being relative to orientation, obviously. The cabinet will then shrink a bit in length.


I hope at least , that I have provided a little food for thought, if nothing else.


Happy Building!.

Just noticed an error in the first combined plot. WSX is in factBLUE and the 1850 RED.
Sorry gents. Haven't found any others though!. I guess that you would have sussed this anyway.

Great stuff, informative posts, and what looks like a very good design. I notice you're using some CAD to do your layouts....can you give any advice about this? Can you define the horn flare parametrically then just fold the central axis? How long does it take to draw up a decent folding scheme?

Keep up the good work!

@tommysb, I wish it were that simple, but cad certainly makes the tedious bits quicker and far more accurate. However, a fairlycomplex design like thistakes about 4 hours to get most of the donkey work done, then another hour or so to check everything is right, before you decide that you don't like something, or something don't quite fit right!. You normally wind up looking for the last 15 litres for a rear chamber, or the throat just doesn't quite look right. It is a lot easier to make corrections to existing work, and nothing gets thrown away. I wouldnormally start a horn by drawing it straight, possibly in four or five straight sections that represent the flare of the horn, then breakit down, and wrap it round the bends. A goodstarting calculation would be to get hornresp or some other program to give you the system volume, work out how big you want to make the front, HxW then enclose the required volume within the required length (plus30 to 40 litres of volume for the internal panels, then start laying it into the box. Most sections can be copied, cut and pasted in with a bit of rotation, but it is always the folds that take the time.If you are thinking of getting cad, or already have access to cad, than I would recommend you use it. Once you learn a few basic operations to get you through the first bits of drawing, getting the restof it just becomes easier and faster with more use. The auto snaps to centre of line, end of line, perpendicular lines and tangent to and from arc functions make life really easy. I would recommend anyone designing to get at least a basic cad program!. Hope this may be of help.

great help thanks! I will have to look for something decent on Linux. I'll let you know how i get on...
Edited by: tommysb

@Tommy

QCad is a good linux 2D package, easy for learning and quite powerful, try to avoid linuxcad at all costs.

@simon

I agree with the 1850 plots, and your horn's.
The WSX one is a bit funny though, that's the one I'm going to attempt to crack on hornresp when I get home to my computer in a week and a half. I've got turbocad too, so will attempt to do a similar model. Using an arc to represent horn length when coupled was a good idea, your diagram reminds me of Grame's (Centauri's) guide to horn folding on AutoCAD.

You've designed a winner, it seems. Have you tried running this without the 15" kick section, comparing it directly with the 1850, under a 12" horn (not yours, apparently it's for 200hz up, maybe you could borrow a pair of MTs from a gent on this site?). Also, have you tried the HDX in the 1850 horn?

Have you gotten around to doing any measured plots as well?

Sorry for all the questions, I would run the sims myself but i haven't got access to hornresp at the moment.

Hi Deadbeat, I wish I could get some properly measured plots for this horn. Anyone in the Dorset vicinity with the appropriate equipment willing to do me a favour?. I can't afford toget it done otherwise. However, I have done some measurements as I have already stated. The mic I'm usingisfrom the days when I was involved with the production of some active studio monitors. We used to use imp for some general test plots. The mic itself is a WM60 cartridge with a line output preamp, calibrated courtesy of liberty instruments. I don't know if anyone is familiar with this mic, but it is reasonably accurate within the frequency ranges that I've been using.(35hz - 12khz +/- 0.5db calibration specs).The preamp has been tweaked and re-calibrated to get it to this stage.So I have measured this horn to some degree of certainty. As I have said before, the horn was measured against a void loaded 1850, and came out louder at all frequencies except for 60 hz and 110hz,where they were equal.The hornresp plots were slightly exagerated at 60 hz for the void, and the hump at around 60hz on the plots posted were not that high. They were at the same predicted level asmy new horn. As far as the upper band above 100hz is concerned, this wasmy next point to verify!. I see you have been thinking along the same lines. Tomorrow nightwill be the next available time when most of the equipment will be back in the workshop for me to use for testing. Those acid heads will insist upon using the rig, as is, for gigs!.There is a possibility that the predicted rolloff at the higher end is not as great, especially when you consider that the peaks above 120 hz as predicted by hornresp aren't there either. The best I cando at the moment would be to produce a graphing of theRELATIVE levels of the 1850/ Void, and the new hornin the range of 35 to 250.
Next time I send you drawings, I'll use native TCW format instead of DXF.
Unfortunately, the 1850 horns were made with M8 t nuts fitteddue to my son's insistance.
I said that M6 would be good enough if using 8 bolts and give enough room for a bit of tolerance. However he insisted on M8 and we had to drill out the chassis to fit the Voids!. They did actually state on the specs that they were M8 fixing holes.
So I don't want to start drilling out the HDX's to make them fit the 1850 horns!.
I'll look forward to the plots you produce for the WSX. I can then judge how far my model was accurate, and then make some adjustmentswhen(if?)you findthe errors. How about AKABAK?, I've heard it's very good. Care to comment?. The arc in front was me re-inventing the wheel again, but it was the result of reading RM's explanation of the HD15 horn that triggered it. Also plotting the horn path at 20mm intervals and taking the tangent from the next 20mm circle seemed to be the most logical and easiest method. I had to devise a means of modelling the extended horn that 'looked right'. Not sure if I've over-cooked it though. Anyone know of a source where the real math is explained and quantified?. (one where a complete dummy can understand it, I mean!)
Got to get Back to more mundane priorities like life in general, or I'llbe an audio divorcee, and I stillhavn't done the plots for the mid range etc. Absolute priority!.
Thanks for the vote of confidence.

Hi Simon.

Congrats on your hardwork, and numerous investigations.

If you go thru some of the older posts on SP, You will see I have also recognised a number of associated factors.

Yes, mid to lower BL drivers will yield flatter, more rounded plots in hornresp. And sound wise, at powers <= 600W, I'm sure many would be warmer and much deeper.

However, when you compare higher BL, lower Vas, Low qts drivers like PD1850/V18-1000/Turbomax 1200/ in larger chamber horns like WSX/CV SL36, you realise, the mid to low Brigade exceed their Xmax, at much lower power input. Especially if Vas is over 250.

Which is why, even though the WSX is designed for RCFL18P300, with V18-1000 it will smoke many, many flh cabs. Due to larger chamber for added low end sensitivity, but high BL /low Vas driver staying in control up to approx 1kw.

Perhaps you would also like to sim CV SL36 with PD1850/V18-1000/18TBX100 ?

There are very few large venues that wouldnt be shook to bits with 8x WSXtras, hanging off an Inf8 Mk2/ 9001.

Edited by: levyte357

@levyte, Thanks, it has been a bit of a hike getting to this stage. Ithink that the boundaries for your 600w figure have just been raised a bit, using this driver. I will agree whole-heartedly with your summation of the low bl, high vas , although if you areinfering this driverhas a vas greater than250,you might have got itmixed with the HDX's brother the FD. The FD is 328, but the HDX is 184. (if you were just generalising -ignore the comment)Also, when comparing with, say the popular C18-650el, The voice coil power is up by over 30%, and comparing thequoteD xmax of the C18, itis up by more than 50%. ( I know the concensus of opinion regardingthe C18.) Never have said that this is any better than the WSX, someone else prompted the comparison to be made in the first place.I have tried to do some comparisons with the Void, and have said that the limit on the new driver is around 800 watts on numerous occasions. Everybody will know that the Void is capable of far greater power handling, and I don't think I have ever implied differently.
I don't think anyone who is a dedicated user of WSX has anything to worry about from this design and driver, especially when the wsx is powered with the big 3 in question.
I would like to say that the original intention for this was to provide an alternative that would cost far less, and so that sims of this with more costly drivers would bedefeating the objectof the exercise. Enough has been done to put things in perspective.
I think I have demonstrated that for a multiple of 4 this cabinetand driver combination is capable ofanaveragespl of over 140dbin half space, with peaks far in excess. This has to be a significant achievement for a budget priced driver.
I have said on a different thread, that the more efficient,higher rated drivers with the bigger amps will always win;- and I agree with you, at1000 watts + the HDX would be burnt toast.
This exercise was not a contest to see what was best, it was to see what could be achieved on the lowest budget, and still provide an acceptable quality of sound and performance.This design has justraised the stakes slightly on the budget end of things.
Anyone who wishes to do some sims using themodel above can alter the rear chamber volume to suita favoureddriver and reach their own conclusions. If anyone would like to suggest slight modifications on the design, like throat area / vrc that would suit a higher rated driver and provide significant improvements on the plot, post themup and let's have a look!. A higher power version could be very interesting.(My own is in the pipeline at the moment, as it is a natural progression from this starting point).
I would like to think that this forum is more about new alternative designs that are free from copyright or patent, not for promulgating the already known virtues of the larger manufacturers.This is just my take onthings, and I am implying nothing by saying this, nor impugning anyones' comments or views. I do valueany input, and try to take everyones' opinion into account. They're all valid. I'm just trying to put it in context.Again, I thank you for the recognition of the effort put in.

I've simulated cv bin, sl 36, ab 36 and earthquake...if you want I can post it