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Looking for some mentoring on a dream system

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sugerman View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote sugerman Quote  Post ReplyReply Direct Link To This Post Posted: 19 December 2017 at 2:27am
Originally posted by kevinmcdonough kevinmcdonough wrote:


The absolute best DIY tops available just now are what are now known as the PM speakers designed by a very experienced guy called Peter Morris. They come in 90 degree dispersion for using on their own (PM90), 60 degree version for using 2 a side if you want more SPL (PM60) or you could even stick a 40 degree horn if you wanted to go 3 aside. They have a ported horn double 12" section and a BMS coax compression driver, so are a 3 way speaker over all. Sound amazing, better than even almost all pro cabs, are still actually a relatively easy build, and are just light enough to still go on a pole mount if they need to. 


These look incredible!!
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sugerman View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote sugerman Quote  Post ReplyReply Direct Link To This Post Posted: 19 December 2017 at 7:35am
@kevinmcdonough

If I decided to be crazy and aim for the PM tops how many would we need to balance with 4 X1's?

... And I guess we would need kick bins between them??

Thanks!

E
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Aman Gebru Quote  Post ReplyReply Direct Link To This Post Posted: 19 December 2017 at 7:36am
Its looking to me like like a bunch of X1's (maybe 8) and 3 pairs of double 15's with 1.5" HF drivers on 60 degree horns is a sensible route to go.

Here is what I see as the pro's to this approach.

If you need to you can just turn up with a pair of double 15's and do a wedding or small band. If you want to be a bit more impressive then chuck a single X1 under the double 15. Cross around 60 to 80Hz and you got a nice compact system. In fact if you had 3 pairs of double 15's and 6 X1's you could do 3 small hire outs at once.

Scalability. For bigger jobs run 2 X1's and 2 double 15's per side. You then have some more X1's and double 15's to make an awesome DJ monitor rig, or do another smaller job at the same time.

For the largest jobs take out 4 x1's and 3 double 15's per side. It would be a bit midtop heavy, but seeing as your using the 15's to meet the subs this is no bad thing.

Its also a relatively easy system to setup. Don't get caught up into thinking more bands are more difficult. If you can setup 1 band correctly you can do 20. Its a bit like a massive analogue mixer. If you know what one channel does you know what all the channels do, be it 8 or 80.

If you really want the best from a setup like this then I would run the double 15's 2.5 way, not 2 way active. This would require each 15" driver being fed from its own amp channel and its own processor channel. Run both the 15's with a HPF of say 80Hz, then run the bottom one with a LPF of around 300 to 400Hz, and the top 15" driver up to the xover point of the HF, so maybe around 900Hz to 1kHz. This way you get the smack of both 15's down low and just use the midrange from the top driver. This is done so that the xover point from one band to the other is done within a relativity close distance. If you run midrange though the bottom 15 as well, then there acoustic centre would be exactly between both 15's, making it a very large distance from there to the HF horn. Its a more difficult setup, but worth it if you want the very best from this type of arrangement.
 
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sugerman View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote sugerman Quote  Post ReplyReply Direct Link To This Post Posted: 19 December 2017 at 8:43am
@Aman Gebru

Really appreciating the specifics on xover points and relationships between components, it is educational!

Embarrassing question: "..... and its own processor channel" — Processor channel means crossover channel, or additional signal processing?
 
I am going to tweak my current setup as far as xover points to better understand this conversation and try some new things.

I am using a DBX PA2 [for now] and have the X1 passing 35–90, the 15"'s from 90–1k2 and the compression 1k2 up... I keep moving these points around but that is the general scheme. 

I think I will try bringing the 15" down a bit more to see what it sounds like.

Any other suggestions on experiments?

Thanks!

E

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Aman Gebru View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Aman Gebru Quote  Post ReplyReply Direct Link To This Post Posted: 19 December 2017 at 9:46am
"Any other suggestions on experiments"

I've not tried the DBX PA2, but if its anything like the original driverack, one experiment you could try is going to the nearest dustbin, opening up the lid and throwing the DBX into it. The original was without doubt the worst crossover known to man. They would have had to done something very radical to make the version 2 even useable. Get a DCX 24/96 and see how it compares sound wise to the DBX.

When I said its own processor channel, yes I meant crossover channel.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote concept-10 Quote  Post ReplyReply Direct Link To This Post Posted: 19 December 2017 at 9:56am
"If you really want the best from a setup like this then I would run the double 15's 2.5 way, not 2 way active. This would require each 15" driver being fed from its own amp channel and its own processor channel. Run both the 15's with a HPF of say 80Hz, then run the bottom one with a LPF of around 300 to 400Hz, and the top 15" driver up to the xover point of the HF, so maybe around 900Hz to 1kHz. This way you get the smack of both 15's down low and just use the midrange from the top driver. This is done so that the xover point from one band to the other is done within a relativity close distance. If you run midrange though the bottom 15 as well, then there acoustic centre would be exactly between both 15's, making it a very large distance from there to the HF horn. Its a more difficult setup, but worth it if you want the very best from this type of arrangement."

This is exactly what you want to do, once you have set it up it should sound very good, and you only have a two box rig, nice for transport and stacking.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote gen0me Quote  Post ReplyReply Direct Link To This Post Posted: 19 December 2017 at 10:46am
Here is why you cant get close to f1. Their mid flares are build on custom mids. They are not just 8" driver or 10" driver they are more like strokers without dust cap in the middle. Voids I guess have phase plugs ala compression drivers. If you compare this kind of horn/phase plug to standard horn like xtro or martins h3 you will find out the second one are not even close to first ones.

Forget about using dj monitors this way. 50 year old shitty build active monitor would be better than anything with dsp delays.

Those Peter Morrisons top have one the best type of kick section design that exist currently on the market. Also compression horn mid. Never heard them thought.

Edited by gen0me - 19 December 2017 at 11:31am
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Post Options Post Options   Thanks (0) Thanks(0)   Quote sugerman Quote  Post ReplyReply Direct Link To This Post Posted: 19 December 2017 at 11:06am
Originally posted by Aman Gebru Aman Gebru wrote:

 The original was without doubt the worst crossover known to man. They would have had to done something very radical to make the version 2 even useable. 

Damn, good to know, I absolutely can not stand poor technology. I had heard this was a decent entry level item...

Are these (below) points crossed over correctly or do I have it completely wrong and am losing Frequencies at the xover point?

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Post Options Post Options   Thanks (0) Thanks(0)   Quote kevinmcdonough Quote  Post ReplyReply Direct Link To This Post Posted: 19 December 2017 at 12:36pm
In terms of the tops speakers you build, you have a balance to find between 15" drivers and 12" drivers. 

15" drivers are good because you get a bit of an extended low end, and it works well if you think you're going to end up using them on their own a lot.  However they can suffer a bit sound wise through the crossover region to the compression driver, and don't always sound great for vocals. Many people prefer a 12" in this regard if they know they're always gonna use it with a sub and so don't need the extended low. Good 12" or good 15"ers these days will all cross over suitably into the X1's.

In terms of then going double, in general I'm not a fan of double 15" cabs.  They tend to be big and bulky for what they are, hard to transport and lift one manned, you're never getting them onto a pole to get some height on them that way, and if you do decide to use them on their own, for all that size and weight you don't actually get that much actual bass out of them. I'd rather take a single 15" (or 12") and a sub, which will not actually take up THAT much more room, but will be easier to manage as it's split over two boxes, and sound much better with proper sub. 

(though if you do decide to go that way using the idea of rolling the bottom one off early is a very good one.)

While it might be a bit much sub for live music or pop music etc, a single 15" top with good drivers each side will keep up with a pair of X1's each side for bass heavy dance music. While a 12" arguably would be smoother for sound, the 15" tops will be a bit more flexible in the future. 

So in total four X1's in total and two good 15" tops will give you a good starting point that will let you make a fair bit of noise for decent sized small events, let you get out and get some good gigs under your belt and hopefully make some money to invest further. 

Then you could look to move the 15" tops to DJ monitors (hence why the extra bass of 15" over 12" is an advantage), and start to look at a bigger system of maybe four X1's a side with some hornloaded tops and kick bins for your "big" system, but still being able to use it as the two X1 and 15" top set up for smaller gigs. 

That then brings things onto crossover points. Which really are a tricky thing.

The problem is that it's all well and good deciding what crossover points you'd like your speakers to be at. But that usually bears little resemblance to what the actual speakers wan't to do. Without some way of measuring them, you're really just taking a shot in the dark.

Now of course, it's an educated shot in the dark, as an X1 is a fairly well known quantity and people have a good idea of what frequencies it's good at playing at, and similarly most people a fair idea of what a 15" top should be doing. 

But to really dial it in and, most importantly, set the delays correctly at the crossover point so everything is in phase, really takes measurement. 

And note, this is the actual acoustic crossover point. Not just the "crossover point" you've set in your processor. That crossover point is essentially a fancy EQ point, a filter that you're saying you want the sound from one speaker to start to roll off at. But that's often quite different from where the actual frequency responses actually overlap. Especially true of bass music where the subs will be quite a bit louder than the mid and hi, and so push the actual acoustic crossover point up surprisingly high.

And then you need to consider than even all that is only part of the puzzle. If you're really doing it properly you also want to look at phase, so you can line that up as much as possible, and dispersion, so that you ave as smooth a transition between the bands as possible and don't end up too Christmas Treey!

Now of course, as a relative beginner no one expects you to suddenly be great a this all, I've been doing this a fair while and I'm still constantly learning all the time, but these are the kinds of things you wan't to think about and research and look into as you go forward. 


k
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osse View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote osse Quote  Post ReplyReply Direct Link To This Post Posted: 19 December 2017 at 1:11pm
My dream system would probably consist of PM tops and Josh Ricci Skhorn subs, size depending on audience.

Have heard neither but they should be something else
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Post Options Post Options   Thanks (0) Thanks(0)   Quote sugerman Quote  Post ReplyReply Direct Link To This Post Posted: 20 December 2017 at 9:18am
Thank you kevinmcdonough

All well noted. I completely understand this is a highly complex, nuanced and interwoven field of outputs and measurements. I need to find the most straight forward route in, and will certainly be looking for someone in my area with long term knowledge. I will learn the most I can reading and tweaking setups in the meantime!

Noted on the 12's. I am really loving the PM tops from what I see so far, I have been reading the original conversation on soundforums.net (https://soundforums.net/forum/low-earth-orbit/diy-audio/11601-new-diy-mid-high) and seems like an extremely high fidelity unit!

I will never be using the system without subs. Or, very very rarely.

I am assuming by what you said that the PM's crossover into the X1 just fine?

I can start making money with the system I have now by doing weddings with a rave twist, the sound is real good and there are non-stop weddings here in Bali so I just need to plan the next step.
 
Four X1's with Two PM (Maybe 60's to prepare for its eventual friends) would be something YOU would be happy with?

How can I go about taking some measurements without breaking the bank?

Again, thank you all!

Evan 





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Post Options Post Options   Thanks (0) Thanks(0)   Quote Hemisphere Quote  Post ReplyReply Direct Link To This Post Posted: 20 December 2017 at 11:09am
Behringer ECM8000 is a surprisingly good budget measurement mic. Plug into a USB soundcard like a Tascam us122 or similar (make sure it has phantom power on the mic input) - I've picked up this combo used for about 60 quid and there's free or low cost software that'll give you a response plot with these tools and a decent interface to analyse it. Room EQ Wizard ie.
Phase 1: Post on Speakerplans
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Phase 3: Profit!
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