BillFitzmaurice.info

At the venue I work, I've blown one of my subs and world welcome advice on driver replacement.

The subs were taken from the disused nightclub across the road and were almost certainly scratch built. Not massively pretty but perfectly useable. I would say they're based on SpeakerPlans 1850 Horn but couldn't be sure. They run 35Hz-95hz.

They were loaded with 600w JBL 2241 units which worked well until we upgraded the amp that drives them to a 3600VZ. I replaced them with Eminence Omegas which lasted 3 months. Waste of time! These were then upgraded to Precision Devices PD918s which have been thumping away nearly everynight for the last 6 years without complaint. Until now!

After recieving poor communication from PD regarding this now obsolete unit, I gave up with them and decided new drivers were the way forward. I have looked at a number of drivers and read various comments, reviews and experiences on use of Celestion units. Specifically the FTR18 4080HDX model looks to have an attractive spec at a very reasonable price.

http://celestion.com/product/86/ftr184080hdx/

I have had many good experiences using Celestion speakers in many situations from the BX units in my Yamaha F15, the C10 and C15s in my old Trace Elliot bass guitar rig, the Truvox in my current Ashton bass rig and even the ancient G15C in one of my WEM cabs.

Any thoughts or advice to why I should not fit this unit? My interpretation of the specs suggest it's suitable for horn loading, the 8mm xmax and 1000w coil would be peice of mind in this demanding application.

Many thanks, Matt

Sorry it's not BFM but thought this the best place to ask!

You may be better suited to ask @ the speaker plan forum since it seems to modeled after one of their designs.

You need to software model the cab to find drivers that have the correct specs to work with it, which includes finding out the safe operating voltage that the driver can work to, and then you have to limit the amp output to that voltage.

I assume there is dedicated horn enclosure software?

I'd love to understand better how different driver parameters affect the response in a given horn. And of course, how a different horn changes the response of a given drive unit. I've sifted through lots of the stuff on here but can't help but feel I'm only scratching the surface.

Most of my work has been done with direct radiating enclosures over the years.
I've used Eminence designer to design a few cabs for for a chap over on another forum which was a success but this is where I want to be to move myself and my company forward.

I have no interest in joining the Speakerplans forum as I'm hoping this will be an isolated incident and If I had my way, the 18s would be replaced with some T48s. I would love to build a full BFM rig for the venue infact although can't see that happening anytime soon.

Many thanks for your patience chaps.

Hornresp is a popular horn modelling programme.
Available at:
http://www.hornresp.net.ms/

I've not messed around with it, but I believe it can be a bit of a handful to get a handle of at first.

If the design is based on Rogs designs use the 1850 or 1851 monsters for max SPL. Or use a Fane 18XB or PD186, the celestian also looks good. All great drivers for horns. The Eminence 18's seem to perform rather poorly.

If i remember correctly the 1850/186 horns are not supposed to run down to 35. How many of them do you have?

Grant Bunter wrote:Hornresp is a popular horn modelling programme.
Available at:
http://www.hornresp.net.ms/

I've not messed around with it, but I believe it can be a bit of a handful to get a handle of at first.

I'll have a look at that, thanks Grant, you're a star!

Bas Gooiker wrote:If the design is based on Rogs designs use the 1850 or 1851 monsters for max SPL. Or use a Fane 18XB or PD186, the celestian also looks good. All great drivers for horns. The Eminence 18's seem to perform rather poorly.

If i remember correctly the 1850/186 horns are not supposed to run down to 35. How many of them do you have?

I had a look at the Fane and other PD drivers and they may well still be used. The reason I asked was I can only find a couple of references to anything other than the PD units being used. I have always respected Celestion as being up there with the best.

I have two close / next to each other so I was hoping for a bit of coupling although I haven't V-plated them or anything. I might roll the HPF up to 38/40 HZ just to protect the drivers better. When we had them, I knew nothing about them so simply put a sweep on them and put the HPF just at the point before it began to roll off steeply..

Just as a foot note and conclusion to the story..

There has been a big shake up at the venue recently and now we're moving forward again. After a touch more research, I took the plunge and have installed above mentioned Celestion.

It's a lovely looking speaker with great build quality. The heavily vented magnet assembly, cast frame and monster suspension certainly look as if they will do the distance. It's been in for two weeks and sounds 'run in' now which is great. It seems to sound a little more controlled than the 918 still in the other box.

Many thanks to those who contributed.

But -and this is respectfully - it seems to me that you've paid out for another driver and every time it gets powered up, it's a fingers crossed approach because you don't seem to have any limiting policy in place. Being a horn cab you've re-loaded, you won't get any warning if you overpower it, just a dead cab. I'm not the one to advise you on non BFM cab modelling to find its safe voltage limit but you have to find a way to do it. I've never been able to take a c'est la vie approach to blown drivers because over here in Britland, an Eminence 3015LF - a much used horn sub driver - is $300 in your money. You will find, if you read enough posts, that all the T30,T39/T48/T60 users - most of them builder/users - on this forum are owners of a Driverack or Behringer DCX2496 for low pass/high pass and limiting. You absolutely have to have one.

wounded horse wrote:I'm not the one to advise you on non BFM cab modelling to find its safe voltage limit but you have to find a way to do it.

+1, especially if it's an 1850. That design only goes to 50Hz, so it barely even qualifies as a sub, and it's going to run out of excursion and thermal capacity very early on if it isn't high passed at 50Hz.

wounded horse wrote:because over here in Britland, an Eminence 3015LF - a much used horn sub driver - is $300 in your money.

Um... I guess you didn't notice, but Vtype's in 'Britland' too... and btw, what's a $ ??
+1 on limiter (although probably only counts as a half as I'm a bit of a newbie!)

If these cabs are based on 1850's or 186's then they are meant to be ran in groups of 4 or more. They will not play below 50 hz in singles or pairs (not very well anyway). They gain lower extension when grouped. There is a significant difference in chamber size between the two as well which will impact the performance of the drivers.

Whilst it still is a 'suck it and see' to a degree, I have implemented more savage limiting (now -6dB up from -3dB) and rolled my HPF up to 42hz with an 18dB/oct roll off.

The Celestion has a greater motor strength, a much larger xmax and a 1000w coil compared to the PD918. I expect the heavier duty driver to be tough enough to work in this application.

I am gonna crunch the numbers though as I have aquired another pair of these monsters with their JBL 2241s still intact. I will measure their dimensions and punch it into my freshly downloaded copy of 'hornresp' so then I have all the info in black and white.

VTypeV4 wrote:Whilst it still is a 'suck it and see' to a degree, I have implemented more savage limiting (now -6dB up from -3dB) and rolled my HPF up to 42hz with an 18dB/oct roll off.

The Celestion has a greater motor strength, a much larger xmax and a 1000w coil compared to the PD918. I expect the heavier duty driver to be tough enough to work in this application.

I am gonna crunch the numbers though as I have aquired another pair of these monsters with their JBL 2241s still intact. I will measure their dimensions and punch it into my freshly downloaded copy of 'hornresp' so then I have all the info in black and white.

You might want to look over at http://www.speakerplans.com They have this design measured, tested and calculated with all drivers from the crappiest Skytec to the big boy Fanes & PD's. All the hornresp input data can be found there as well.
Both the 1850 and 186 are great cabs but they will eat your drivers if not highpassed correctly.

I'll have a look over there, thanks..

My slight issue is that i'm not 100% sure they're 1850 horns, they might be Earthquake / CL36 copies..

I'll post some pix over there..

Cheers Chaps!