brennyE Posted December 3, 2006 Author Share Posted December 3, 2006 oooops! so i did [:$][][:#] Hmmm I suppose you are right. Although now I have discovered how easy (and not to mention kinda fun) it is to build your own amplifier, i feel I am going to be churning out many more in the next 2 years[] I do have a few amplifiers around the house when I add them up...... 2 5channel receivers, 1 -220W amp, 2- 350WRMS amps (getting finished off) and the HK in my bedroom.....not to mention the behringer on the way[] so now I want to stop buying amplifiers for a while and build my own! I want to build a tube amp, and a small class A amplifier to start with.[8-|] For the record......I cant wait to get this sub ported and fired up!!! If it doesnt perform better than the RW-12 I am going to be majorly pi55ed off! but like you said....its all about the learning......its all about the learning brenny......... (begins to tear hair out in anticipation) Quote Link to comment Share on other sites More sharing options...
nicks sig Posted December 3, 2006 Share Posted December 3, 2006 Hey Brendan. Things seem to be coming together pretty well... I've actually heard the sub playing in person (...er, not that you can do it anyother way...lol 'heard a recording'......); back on topic, must say its not a bad effort at all for a first enclosure and sub choice. Looking forward to hearing what it will be like with the new amplifier, will be quite a goer. Do feel your pain though... i too kick my self for choosing the driver i did, but as said, you cant say you havnt learnt anything from doing it... lmao... look at all the old enclosures i have laying around? you'll get there too... haha. Good luck man! and congrats on saving the whole project ya self! (our wages are abismal at the best of times...). Nick. Quote Link to comment Share on other sites More sharing options...
darkside Posted December 3, 2006 Share Posted December 3, 2006 Actually, I've had some wierd results off of Win-ISD too. Ionce modeled a Madison Dragon 18(http://madisonamps.com/products/drivers/dragon.htm) and got like 75dBsat 7hz! Granted, it was in a 20 cu. ft. box (33" x 33" x 33" cube). Also I can tell you now, brenny, you are not that young, as I still live with my parents... Quote Link to comment Share on other sites More sharing options...
brennyE Posted December 4, 2006 Author Share Posted December 4, 2006 DARKSIDE: 75db at 7hz! wow that really is wierd..... especially with an FS of 34hz! not to mention an Xmax of 19mm........I suppose the only true way to see how a sub performs before you build it is test one exactly the same as the one you are building[] I love doing designs on win isd, but i always take the results with a grain of salt. As Dr Who said, their are many factors that these programs cannot take into consideration. NICKS SIG: oh yeh we are going to have some goooood bass at parties with the 2 15's going now[] should be fun. Also I founf out in the new house we arebuilding we are going to have a loft in the shed (upstairs level with retractable stairs) so Ill have a nice little dedicated listening room....a very big one as the shed is bigger than my current house [] Quote Link to comment Share on other sites More sharing options...
darkside Posted December 4, 2006 Share Posted December 4, 2006 Yeah, I sure would like to build that, but it wouldn't happen anytime soon if at all... Quote Link to comment Share on other sites More sharing options...
brennyE Posted December 11, 2006 Author Share Posted December 11, 2006 I just got some more time to do some more fidling with the subwoofer on win isd (amplifier is almost payed off) and found something that worries me greatly! Going through the help files, I decided to check the delay time on the port so I can see if it will sound crappy (could have kicked myself for not doing this earlier!) and found that I have a 33ms delay at 30hz, 22ms at 35hz and so on so forth........After reading the help file this sounds very bad indeed as it says you should have at most 14ms at all the frequencies your music will be listened to at! are these numbers I am getting as bad as they look to me? if so how noticible will the port noise be? I know the way to fix this is to add more ports, or more port diameter, but I cannot do this because with my current calculations with 2 85mm ports, they both have to be 15inches long (which is as long as I can have them in my enclosure) I would very much appreciate it if any one had any views/help for me, as I want to port this sub because apart from the delay it gives me great frequency response, SPL and low cone excursion before 30hz (where the sub will be "cut off" at) Look forward to hearing back! Quote Link to comment Share on other sites More sharing options...
DrWho Posted December 12, 2006 Share Posted December 12, 2006 Delay time on the port? Are you referring to group delay? The audibility of group delay is dependant on the frequency range you're talking about. For example, 50ms at 20Hz is much much less audible than 15ms at 200Hz. The audible result is a smearing of the notes in that frequency range - a loss of definition. For subwoofers, I personally try to design for a group delay peak below 50ms at the F3 of the system. And then you want a gradual decrease as you go down in frequency (like cut the group delay in half for every octave you go up). You want to avoid large peaks as they will be indicative of resonance in the system (especially since they'll often be near the tuning frequency and impedance peaks of the system). Group delay, however is not a straight up signal delay - it's a measure of how fast the phase is changing. As far as port noise, this is going to directly correlate to the air velocity - not the group delay response. The more velocity, the more chuffing. The ideal rule of thumb I've always heard is to keep it under 10 m/s. But this is rather unreasonable and most people go by the 20 m/s rule. However, you'll find a lot of subwoofer manufacturers going with velocities as high as 50 m/s at peak output. The idea here is that you're usually going to be listening at quieter volumes (bringing the port velocity down), but for those times when you've got things blasting you're probably not worried too much about how clean the signal is. Quote Link to comment Share on other sites More sharing options...
colterphoto1 Posted December 12, 2006 Share Posted December 12, 2006 pie are squared What? you're an idiot look at it again pi r squared [] Like my Dad (one of those double-engineers- Doc will understand) used to say: "Pie are not square, pie are round" Ok, engineering humour isn't the best, I know. M Quote Link to comment Share on other sites More sharing options...
Jay481985 Posted December 12, 2006 Share Posted December 12, 2006 In line with drwho said keep the port velocity at less then 33m/s What i try and see when using win isd is half the max rms wattage and then keep the port velocity under 33 m/s Also group delay is subjective as some will not even notice it when it is at 50m/s Quote Link to comment Share on other sites More sharing options...
darkside Posted December 12, 2006 Share Posted December 12, 2006 Group delay??? F3??? How fast phase is changing??? I'm so confused!!!!![*-)][:^)] Quote Link to comment Share on other sites More sharing options...
DrWho Posted December 12, 2006 Share Posted December 12, 2006 F3 is the -3dB point of the frequency response. It's just easier to say F3 (or F6 or F10) than to say "the -3dB point" [] As far as phase....look at the phase response plots in winISD. You should note that different drivers with the same frequency response will have the same phase and group delay response. But the steeper the frequency response rolls off, the faster the phase changes and the higher the group delay is. Quote Link to comment Share on other sites More sharing options...
CAS Posted December 12, 2006 Share Posted December 12, 2006 pie are squared What? you're an idiot look at it again pi r squared [] Like my Dad (one of those double-engineers- Doc will understand) used to say: "Pie are not square, pie are round" Ok, engineering humour isn't the best, I know. M I love nerd humor!!! I'm serious!!! When at NASA we had all sorts of ultra-academic jokes and limericks around. I love it!!! Quote Link to comment Share on other sites More sharing options...
brennyE Posted December 12, 2006 Author Share Posted December 12, 2006 ah I feel at peace again....all is as it should be. at half power, which I am calling 400WRMS ( I am not about to believe the claimed 1200WRMS power handling) the port air velocity is a peak of 32ms at 30hz, and anything below that doesnt matter becasue it is all being cut off! I knew this subwoofer was going to "sound bad" generaly speaking before I even started this project. I was just worried for a moment their that it would sound so bad it would be unusable. apparently not. And also, to fit the ports in that I have in mind can I use these port kits http://www.jaycar.com.au/productView.asp?ID=CX2685&CATID=&keywords=port&SPECIAL=&form=KEYWORD&ProdCodeOnly=&Keyword1=&Keyword2=&pageNumber=&priceMin=&priceMax=&SUBCATID= I wanted to use these because they are angled up at 30degrees making it easier in my enclosure to fit the length of the ports. Also while im at it I may as wel ask some questions to save asking them later! ok, when I port the sub should I take out all of the accustic stuffing I have in place? and with the amplifier I am getting for the sub, I actually believe that it will be able to deliver in excess of 1000WRMS in bridged mode (by looking at the amps internals it looks like it could do the job), being such a substantial amount of power, what cabling should I use to internally and externally wire the sub? (the amplifier will probably be sitting on top of the subwoofer making for very short wire runs) and last but not least, I read somewhere that PA gear (like the EP1500 I am getting) needs high gain input signal to be able to work at it's best. this should not prove a problem for to long if true because an equaliser with a activ crossover is on the way soon after the amp.when i first get the amp I will be playing the the amp off my HK3480's subwoofer out jack, lowpassed at 100hz (a bit to high but I can deal with it for a while) Thanks again for setting me straight! Quote Link to comment Share on other sites More sharing options...
Jay481985 Posted December 12, 2006 Share Posted December 12, 2006 acctually...... the hk3480 lowpass is 150 hertz....... you can get in line attenuators that would help basically its a crossover on the rca line and can get from partsexpress. Also yeah you should always go with half rms watts as most speakers do not do well with max power. that in terms of group delay, excursion, port velocity etc. remember half rms and full rms is only around 3 db (a little louder) but is so much more so when seen on winisd with said above. Quote Link to comment Share on other sites More sharing options...
brennyE Posted December 12, 2006 Author Share Posted December 12, 2006 wow 150hz??? what were they smoking when they created that magical figure. I suppose the HK was only designed to drive small speakers in an office or spare bedroom (thats what the manual says anyways!) so the high crossover for the sub would make sense in that case. Although I think 120W per channel is a tad bit large for a reciever designed to drive small speakers in small rooms. oh and with that attentuator for PE I shall have to look into that. But I live in Australia so I'll have a look now to see how much shipping is (or if I can get a simular product here) ahhhh if I lived in the US I would have a TC-2000 15" in my room right now (and would probably be saving for the LMS-5400) ahhh I how I do love TC sounds (but the loving relationship with me and TC will never happen due to the huge shipping costs, fees and warranty problems involved with ordering one to the land down under) Quote Link to comment Share on other sites More sharing options...
Jay481985 Posted December 12, 2006 Share Posted December 12, 2006 http://www.partsexpress.com/webpage.cfm?DID=7&WebPage_ID=3&Start=2&ObjectGroup_ID=745&sm=1&so=2&desc=ASC Quote Link to comment Share on other sites More sharing options...
brennyE Posted December 12, 2006 Author Share Posted December 12, 2006 cheers jay Quote Link to comment Share on other sites More sharing options...
darkside Posted December 14, 2006 Share Posted December 14, 2006 OK, so I went back to WinISD (I use pro alpha) and redid the MadisonDragon thing, 20 cu ft box etc etc. Well the first results were off 1watt. I went back and redid it with the proclaimed 1200 watts RMS ofthe driver and got 98 dBs at 5 hz! Now, call me skeptical, but I'm notsure that's possible with that woofer in a box that big as the boxitself is so huge it probably cant handle all the power... Quote Link to comment Share on other sites More sharing options...
DrWho Posted December 14, 2006 Share Posted December 14, 2006 what's this obsession with 5Hz??? Quote Link to comment Share on other sites More sharing options...
darkside Posted December 14, 2006 Share Posted December 14, 2006 No obsession, its just really low and I don't think its possible with that sub... Quote Link to comment Share on other sites More sharing options...
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