Twin 18 P-Audio cab help
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Category: Plans
Forum Name: Other plans
Forum Description: Discussion / Questions about all the other plans
URL: https://forum.speakerplans.com/forum_posts.asp?TID=2364
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Topic: Twin 18 P-Audio cab help
Posted By: semtexsystems
Subject: Twin 18 P-Audio cab help
Date Posted: 10 August 2005 at 2:03pm
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Hi Ive been searching the www for ages and havent managed to find an answer to my problem, We have just bought 2 P-Audio subs model number p180/2242 where not sure on the best type of enclosure to build for them, i see the plans here for the P-Audio SD 18 but the sub spec is different, will this matter? if so any recomendations would be apreciated, Also as we have 2 would it be best to build 2 singles or 1 twin? we mostly play drum and bass with some hardcore at outdoor events heres the sub info http://www.p-audio.co.uk/products/db_product_1_5_p180_2242.htm - http://www.p-audio.co.uk/products/db_product_1_5_p180_2242.h tm many thanks Ben ------------- www.semtexsystems.co.uk |
Replies:
Posted By: ceharden
Date Posted: 10 August 2005 at 4:56pm
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The type of enclosure I'd suggest would normally be different for the
two types of music you play. For Hardcore, a horn loaded cabinet
would probably give better results, although probably not with only two
subs. For D'n'B the emphasis in the bass is much lower and would
suit an bandpass (X1). Since you want to use your subs for both,
the compromise and the simplest solution is to build a reflex (ported)
cabinet such as the G Sub. The decision between single or double cabs
is purely your choice on how portable you want them to be, ease of
stacking etc. What does the rest of your rig consist of? Two 18" subs for outdoor dance events seems a little small. |
Posted By: semtexsystems
Date Posted: 10 August 2005 at 6:33pm
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Hi As we are just building our system i think we will go for the bandpass design because of the lower end bass for the DnB, we will be getting more subs (and mids)before we do our next outdoor event, maybee some 15's or 12's to give more punch? I take it there is no sound difference in having 2 singles or 1 double rest of rig..... mmmmmm not too much atm as where just setting up 1) qsc-rmx2450 amp 2) a pair of peavey full range (white widdow cones) 3) sageline 2k amp if i decide to go for the bandpass enclosure do i need to recalculate the mesurements? or do i make it to the size of x1 on this site? cheers Ben ------------- www.semtexsystems.co.uk |
Posted By: ceharden
Date Posted: 10 August 2005 at 7:49pm
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Although the X1 would probably work with your driver as-is, it would be
best to check the tuning. Have you looked at any software such as
WinISD for calculating the response of cabinets? From the X1 plans on the site calculate the chamber volumes and port sizes then use them to simulate the cab with the original SD18 and your driver in WinISD. If both look similar, no changes will be needed. Dom has some X1's which have been altered in shape to make them easier to stack; you also might want to take the basic design and use it as a starting point for your own versions. The X1's won't sound good for hardcore as you need to cross them over to something else around 80-120Hz and won't deliver the punch you need. A few forum members have gone down the route of using X1's up to 80Hz then HD15's up to 160-200Hz with good results I believe. They'll be fine with the peavey's for most things however, and unlike horns are ok with just one per side. There's no real difference between two single reflex boxes stacked together and a double, in fact some doubles are exactly that with no internal connection. |
Posted By: semtexsystems
Date Posted: 11 August 2005 at 2:16pm
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Hi again thanks for your response again Ceharden as i said at the minute we want deep rolling bass for DnB, the punch will come later with some 15's just spent about 2 hours looking @ winISD both beta and pro... whooooosh!! over my head it goes i keep getting errors with the values i input from the specs on the site above, theres about seven problems in total also I have no "fle" or "kle" value Is there any other software you can recomend maybee a little more user friendly for us inexperianced noobs...lol thanks Ben ------------- www.semtexsystems.co.uk |
Posted By: ceharden
Date Posted: 11 August 2005 at 2:46pm
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I will concede that WinISD Pro can be a little fussy when entering
driver parameters. Read the help, it explains how to enter them
without getting error messages. You only need to input a few of
the params to get basic results, it can calculate a lot of them itself. While iit's not as powerful, WinISD beta is a lot simpler to use, I'm surprised you were having trouble with it. To start with, try using one of the included drivers to get the hang of it. Most other programs start getting more complicated again. * Start the program and select New from the toolbar * Pick a driver or enter your own parameters (new driver) * Select no. of drivers and type of enclosure then Finish * Play with the box size and tuning frequency With WinISD pro you can (more usefully) input the port length or tuning rather than just the tuning freq in the beta version. Hope this helps. |
Posted By: semtexsystems
Date Posted: 11 August 2005 at 4:16pm
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Thanks i got all the values in with no errors and had a play about with the graph thingy but still did'nt realy know what i was lookin for. However i did find that the line on the chart was almost identical to the eminance 18 kilomax( within 2 mm), wich is a recomended sub for the g sub design on this site, will this enclosure give me the bass im looking for? if so i will just use the mesurements on this site and make a couple again many thanks Ben ------------- www.semtexsystems.co.uk |
Posted By: rastaman
Date Posted: 11 August 2005 at 4:44pm
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You mean the C sub? The G sub doesn't mention any Eminence driver as being suitable. The fs (resonant frequency) of the two drivers is way different The Kilomax fs is 33Hz the P-Audio is 42Hz. The C sub must be tuned below 40Hz as it's for drivers with a low fs and it promises 35-90Hz, you can't get lower than fs from a driver unless it's in a horn (generally speaking). You're probable best bet is to take those values you plugged into WinISD, model the ported, 4th order and 6th order drivers, get the 'optimum box size' from the program and go from there. You'll probably need to tune the cabinet in the 45-50Hz range (ie it won't go any lower than this). I don't think sticking it in an unmodified C or G sub would be a good idea, it's not close enough to any of the recommended 18"s for any of the designs on the site, it's Qts is rather high, as is it's fs (read the speakerplans FAQ it will explain why) |
Posted By: semtexsystems
Date Posted: 11 August 2005 at 5:03pm
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thats right m8 the c sub.. o.k. now im gona ask a big favour i aint realy got a clue about frequencys and cab tuning! i keep reading all this stuff bout it all and as i say earlier its straight over my head. if i email the .dri file i created to you or anyone else who knows what there doing would you be able to take look and maybee give me some box / port dimensions? i know this soundas a bit cheeky but i dont want to spend a load of cash time and effort on a crap cab that aint gonna sound any good. i dont have much to offer in return however if your into your DnB / Hard house / Hardcore etc... we will gladly host a mix or 2 on our site plus we will place a link to your site. check http://www.semtexsystems.co.uk - www.semtexsystems.co.uk theres not much on it atm as its still under construction but it is getting better day by day. tell me to pi55 off if u like but i dont know what else to do as we have had thiese subs for about a month now already and they still sit in there box waiting to start partying thanks alot ben ------------- www.semtexsystems.co.uk |
Posted By: rastaman
Date Posted: 11 August 2005 at 5:15pm
OK, here's a plot I did in WinISD beta, just for the heck of it. I made
an alpha file as well, but it doesn't do boxes (do I need to upgrade?).
Looking at it, it looks like you would need a really large vented box
to get a decent response out of it. Thats just running with the defaults, you could play with the volumes and tunings of the 4th and 6th orders to get a smaller box with a higher tuned frequency. Either way, those drivers will need a fairly large box to ever go fairly low. What sort of frequency range were you hoping to cover? |
Posted By: semtexsystems
Date Posted: 11 August 2005 at 5:38pm
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top man there is an update http://www.linearteam.dk/default.aspx?download=winisdpro - http://www.linearteam.dk/default.aspx?download=winisdpro http://www.linearteam.dk/default.aspx?download=winisdpro -
as i say i dont realy know much about frequencys all i know is that we want deep rolling bass that rattles your spine. we mainly play DnB and we will be adding some 15's or 12's at a later date to give the system more punch. however ceharden recomended about 80 - 120 hz are the caculations you did for the 2242 http://www.p-audio.co.uk/products/db_product_1_5_p180_2242.htm - http://www.p-audio.co.uk/products/db_product_1_5_p180_2242.h tm or the 2241 http://www.p-audio.co.uk/products/db_product_1_5_p180_2241.htm - http://www.p-audio.co.uk/products/db_product_1_5_p180_2241.h tm we have the 2242's and ths frequencys quite different ------------- www.semtexsystems.co.uk |
Posted By: rastaman
Date Posted: 11 August 2005 at 5:49pm
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2242's I entered the data from the link you provided, I can post a copy
of that if you need it. I think is you tuned it higher, you could make
the boxes much smaller. Don't forget I'm no expert either. It looks to me halving the size of the box to 91.65l, without changing any other parameters, gives you a much less steep response curve, with a -3dB point @ 60Hz and a 0dB point of around 80Hz, the response isn't flat but it's within a dB, and I'm sure tweaking values would probably help. |
Posted By: ceharden
Date Posted: 11 August 2005 at 8:20pm
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Here are some alternative simulations I knocked up (after having my own
long argument with WinISD Pro, it's got some horrible bugs, have gone
back to Beta). If you are willing to go for the added complexity and size of a 6th order bandpass, there is some definite gain to be acheived. They'd certainly give you plenty of low bass, maybe lacking definition though. Personally I'd go for a reflex enclosure of about 200litres tuned to around 40Hz. While that seem a large enclosure, I use a lot of similar single 18" bins (B&C 18PZB46 loaded) and with well placed handles they're managable by one person. Good general-purpose subs for all music. Since this is your first excursion into cabinet design, from experience I'd recommend a simpler cab, reflex boxes are more forgiving on the tuning and much easier to build. Test boxes out of MDF could be a good plan, see what works/what you like the sound of. 
|
Posted By: semtexsystems
Date Posted: 16 August 2005 at 8:31am
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Hi o.k. im nearly there! im think im gonna build a 6th order box working with the above volumes, and as you suggested i will build a test box out of mdf first. my next querry is the vents, looking at winisd i think i need the following ports using a port diamiter 64mm Front chamber = 4 x 72mm = vent match 0.05 Rear chamber = 4 x 28mm = vent match 0.02 i think this will be ok as the vent i read the vent match should be below 0.16 in order to avoid whistling. could someone please confirm that im working this out correctly thanks in advance Ben ------------- www.semtexsystems.co.uk |
Posted By: ceharden
Date Posted: 16 August 2005 at 3:40pm
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I get the same when I use your port sizes. The box volumes I
suggested are quite large, gonna be a pretty big cab but you'll find
out whether it's managable when you build the test box. There
might be some scope to make it smaller at the expense of a bit of low
extension. What WinISD beta can't tell you is whether you'll have problems with driver excursion. The Pro version can, but the bugs seem to stop me inputting all the parameters.s Glad the image works, I can't test it myself as it's hosted on my own server in the house. |
Posted By: semtexsystems
Date Posted: 16 August 2005 at 5:29pm
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thanks alot for your help! as i say im gonna go for it and i'll post back in a week when i have got round to building it and let you know how it goes.. but before i do what do you mean by driver excursion? ------------- www.semtexsystems.co.uk |
Posted By: ceharden
Date Posted: 16 August 2005 at 5:45pm
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Excursion: How far the coil moves in the magnet from its mean (no
signal) position. The P-Audio you're using has an X-max of 6mm
which means it can move that far in either direction before the coil
moves too far out of the magnet. If you drive the loudspeaker
such that the cone is moving more than xmax you will first start to get
non-linearities in the sound wave it produces. If you drive it
even harder you can damage the loudspeaker by trying to push it further
than the suspension will allow and in some cases the coil may hit the
inside of the magnet in one direction. Basically the cabinet should be designed such that in normal operation the excursion of the driver does not exceed Xmax. Make sense? |
Posted By: Centauri
Date Posted: 16 August 2005 at 8:13pm
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Had a play with WinISD Pro myself (new version DOES have a few
issues). First problem is the specs on the link above are
INCORRECT - see P.Audio's http://www.paacoustic.com/ - official site . The specs here work fine in Pro. The above tuning suggestion will run out of excursion at 51 Hz at 400W, and it looks like the port diameter of 64mm will be too small - 102mm should be ok. The ported box is also excursion limited at 60Hz to 417W. In both cases, increasing the lower tuning to 50Hz will increase the power capabilty to 600W excursion limited - you trade off low extension for a bit extra volume. Cheers Graeme |
Posted By: semtexsystems
Date Posted: 16 August 2005 at 9:00pm
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hello mmmmthanks. Just when i thought id got something sorted! O.K. To increase the lower tuning to 50Hz will i need to change the box volume? or do i do this by just changing the vents? thanks ben ------------- www.semtexsystems.co.uk |
Posted By: ceharden
Date Posted: 16 August 2005 at 9:33pm
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I'm not sure the european P-Audio specs are purely wrong, comparing
with the official site shows a large difference between the two
drivers, they even look different in some respects. We need to be
doing the calculations with the drivers Ben actually has. So, Ben, where did you buy the drivers, and do they look more like the pics on the UK site, or the official (international) site. You'll need to alter both the volume and port size but lets check we're using the right driver params first. |
Posted By: Centauri
Date Posted: 16 August 2005 at 9:43pm
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The specs on the UK site just don't gell - the correlation between Fs,
Sd and Mms for instance is incorrect. Makes all the other specs a
little suspect. It could well be that they have upgraded the
driver recently, but accurate figures would be nice. In my sim I just adjusted port tuning (both front and rear), which shifted the response curve upwards a little in exchange for decreased excursion. Cheers Graeme |
Posted By: LunchieTey
Date Posted: 17 August 2005 at 2:35am
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Not sure how much this will help BUT... I use the p180/2241(different I know) in a 6th order cab of 120ltr/41hz rear and 70ltr 90hz front. The sims show it's not excursion limited until 36hz at 600wrms. 200ltr rear chamber seems mighty big for a single driver enclosure? My boxes are 200 total and seem quite big in person that's for sure. The plus side of these boxes is they sound great and are particularly adept at rattling some roof sheeting given more than 750wrms each(even 1.5k isn't a big drama-30hz highpass and slight eq dip on 20/25/30hz sliders(-3db)) Even with the 2242,low end extension won't change much at all if you knocked at least 50ltrs off the rear chamber.
------------- Speaker addict |
Posted By: semtexsystems
Date Posted: 17 August 2005 at 4:23am
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I had no idear that building a box would be such a pain! The subs where purchased from ebay so not to sure if there uk spec or not. There is some paramiters on the box they come in however i dont have them here, there at a friends house, i will ask him to post the deitails from the box when he finnishes work at 3pm (uk) thanks ben ------------- www.semtexsystems.co.uk |
Posted By: semtexsystems
Date Posted: 17 August 2005 at 11:16am
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HI there Here are the specs for the drivers we have. Many thanks Peter
------------- www.semtexsystems.co.uk |
Posted By: Timber_MG
Date Posted: 17 August 2005 at 11:59am
| HI, the specs on the box are worthless in my book. The C18-650EL for instance is specced as having a BL of 19 on the box, which is fortunately not true. |
Posted By: rastaman
Date Posted: 17 August 2005 at 12:54pm
| Weird, I thought that was the sites cockup, I remember looking at the specs on usspeakers.com and they were well different from the p-audio.co.uk, so which site has the correct values? I remember thinking it weird the C18-600 looked better than the C18-650. |
Posted By: Centauri
Date Posted: 17 August 2005 at 12:59pm
Good grief - different again  .....But at least those figures do gel. However it makes little difference to the simulation - the same limitations apply. Cheers Graeme |
Posted By: semtexsystems
Date Posted: 17 August 2005 at 8:23pm
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do you mean the the front and rear volumes stay the same? if so i think i will go ahead and build testbox to the dimensions mentioned earlier if not i have no idear what ill do thanks ------------- www.semtexsystems.co.uk |
Centauri wrote:
strange!!Posted By: semtexsystems
Date Posted: 18 August 2005 at 5:58am
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Hi, I just sent a email to paudio (both uk and usa)to see what they have to say on the matter, lets hope that someone there knows there stuff and can shed a bit of light on the subject. i'll post back here with any replies they send me as soon as i hear anything regards Ben ------------- www.semtexsystems.co.uk |