davewantsmoore Posted December 3, 2018 Posted December 3, 2018 2 hours ago, hollowboy said: This is my go-to page For example.... If you look at this pic from that page Two things are causing the response to be higher than zero. Room gain, and room modes. The room modes are causing ~+6dB peaks ... and causing nulls which are theoretically infinite (ie. total cancellations of the sound ... so a long way below zero .... you don't see them clearly due to finite frequency resolution) The room gain is causing the slow rise, beginning at about 100Hz, and increasing all the way down to ~+30dB at very low frequencies. You can see for example, the 11dB peak at 45Hz. This would be made of of some modal peak and some room gain.
Primare Knob Posted December 3, 2018 Author Posted December 3, 2018 It can only be ~+6dB ... so it is likely a combination of effects you're seeing in this data. More charts of things in different places could start to separate them out.No EQ or bass lift, just room. Concrete slab with double brick walls.
davewantsmoore Posted December 3, 2018 Posted December 3, 2018 43 minutes ago, Primare Knob said: No EQ or bass lift, just room. Yep - OK. So the room gain part, can be trivially corrected for, and doesn't change anywhere in the room. The mode part will change with the arrangements of sources, listeners, etc .... and needs more "thought". Consider them independently. 1
Primare Knob Posted December 3, 2018 Author Posted December 3, 2018 Yep - OK. [emoji106] So the room gain part, can be trivially corrected for, and doesn't change anywhere in the room. The mode part will change with the arrangements of sources, listeners, etc .... and needs more "thought". Consider them independently.I was getting to that conclusion from your replies. Edit: based on this, will a dual 12" X 2 subs produce 105dB in my room, and some below? I got the feeling that the specs of 19Hz DIN from my subs aren't exactly a reality.
davewantsmoore Posted December 3, 2018 Posted December 3, 2018 56 minutes ago, Primare Knob said: dual 12" X 2 subs produce 105dB in my room, and some below? 4x 12" drivers? (ie 2x 2x12") Yes... a basic calc (ignoring room gain) says 4x 12" pistons need to move ~9mm to make 105dB @ 20Hz ..... but to make this SPL at 10Hz, they need to move 36mm (ie. 4x), which they probably can't. ... but you very likely don't need them to hold their same SPL capability as you drop lower in Hz, due to the increasing room gain.
Primare Knob Posted December 3, 2018 Author Posted December 3, 2018 4x 12" drivers? (ie 2x 2x12") Yes... a basic calc (ignoring room gain) says 4x 12" pistons need to move ~9mm to make 105dB @ 20Hz ..... but to make this SPL at 10Hz, they need to move 36mm (ie. 4x), which they probably can't. ... but you very likely don't need them to hold their same SPL capability as you drop lower in Hz, due to the increasing room gain.Can you tell me how you got to these numbers? I can't seem to model it as the max I find is around 99dB for 9mm excursion of 2x12" sub. Do you assume a +6dB for a second sub at 20dB as it is within 1/4 wavelength distance for that frequency?
davewantsmoore Posted December 3, 2018 Posted December 3, 2018 10 hours ago, Primare Knob said: Can you tell me how you got to these numbers? I can't seem to model it as the max I find is around 99dB for 9mm excursion of 2x12" sub. Do you assume a +6dB for a second sub at 20dB as it is within 1/4 wavelength distance for that frequency? That's right..... So 1double the excursion (18mm) is double the volume displacement (which is +6dB) is 105dB. Yes, it is +6dB when you double the number of drivers.
Primare Knob Posted December 4, 2018 Author Posted December 4, 2018 Modelling with the Dayton 12" RSS315HO in a dual opposed, I can do with a cabinet net volume between 25-35 litres, which comes down to a cabinet size of 370mm - 400mm square box. The 35 litres cabinet does model 2dB more output at 20Hz. This is calculated on 1400W of intput.This includes, 2x 3.5 liter for the drivers, 1 x internal bracing, double thickness baffles.The same 400mm cabinet with a single Dayton RSS390HO models 1.5dB less output with 800W, roughly the same as the 370mm cabinet with 2 X 12".This includes, 1 x 5.5 liter for the driver, 1 x internal bracing, double thickness baffle.Both the RSS315HO and RSS390HO sell roughly for the same price,$300aud each landed here, only I need twice the number of drivers for the 12" version.Both versions will do the job.To keep the cabinet small I am back at looking at a Pro Amp instead of a plate amp.I am considering the iNuke6000 and a fan mod to keep amp and fan noise low as it can do 2200W RMS into 4ohm.For the single 15" I might consider the crown XLS2500 that is up for sale in the classifieds, or I could spend the $600 in savings towards the Hypex FA502, but that will increase box size as it is recommended to put it in its own sealed enclosure.
davewantsmoore Posted December 4, 2018 Posted December 4, 2018 2 hours ago, Primare Knob said: 370mm - 400mm square box Nice. This is a pretty tiny subwoofer. 2 hours ago, Primare Knob said: The 35 litres cabinet does model 2dB more output at 20Hz. 2dB is reasonably significant. 2 hours ago, Primare Knob said: This is calculated on 1400W of input. I think that's not a deal breaker .... but keep in mind this is a lot of power to ask the driver to turn into heat.... but as always, it's all a matter of trade-offs. 2 hours ago, Primare Knob said: Both the RSS315HO and RSS390HO sell roughly for the same price,$300aud each landed here, only I need twice the number of drivers for the 12" version. Seems like the single driver, then. 2 hours ago, Primare Knob said: To keep the cabinet small I am back at looking at a Pro Amp instead of a plate amp. Keeping the electronics away from the subwoofer, will give you a lot more flexibility with moving/placing the sub. 2 hours ago, Primare Knob said: towards the Hypex FA502 The hypex modules have built in DSP. You might want that... you might not (as you have DSP elsewhere).
Primare Knob Posted December 4, 2018 Author Posted December 4, 2018 I done a bit more reading and it seems the iNuke6000 is just a sort of bridged iNuke3000, and asking it to deliver 4ohms is considered challenging. Does someone know if the ratings of the Crown amplifiers are RMS or peak. The Crown side doesn't mentioned it, but a couple of retail site quote it as RMS. Edit: The specs say Maximum average power rating at 0.5% THD at 1kHz.
Wozza_Lee Posted December 4, 2018 Posted December 4, 2018 Having owned a few pro amps the iNuke 3000 is the bang for buck winner.Fan mod is a must, I have not used the crowns but hear good things,but are a bit more $$.There are other behringer amps that seem to be good. But with the replacement of the iNuke they will be hard to beat
Wozza_Lee Posted December 4, 2018 Posted December 4, 2018 Lots of time I have used/know of people that use the iNuke 6000 with 4ohm amps without trouble 1
Primare Knob Posted December 5, 2018 Author Posted December 5, 2018 https://forum.speakerplans.com/behringer-inuke-nu6000-vs-kam-kxd7200-bench-tested_topic69202_page1.htmlI found some test measurements on this forum. It looks like for my 800W peak for a single 15" should be fine and keep distortion levels low and heat low. The only thing that I don't know how to take is, the power draw and feedback seems to be somewhat uncontrolled. Should I put it on its own power point and circuit?
davewantsmoore Posted December 5, 2018 Posted December 5, 2018 54 minutes ago, Primare Knob said: The only thing that I don't know how to take is, the power draw and feedback seems to be somewhat uncontrolled. Should I put it on its own power point and circuit? I would not think so .... but if you have the option available, then why not?!
Primare Knob Posted December 6, 2018 Author Posted December 6, 2018 I've done a bit more reading and found a couple of threads that the crown XLS /XLI have a roll off starting above 20Hz that doesn't make this a good match for a sealed subwoofer. I am still struggling to understand that a Behringer is a good amp. They are pushing things to fit a cheap budget, and I find it difficult to believe that you will end up with a good amplifier. It does a job, but to what extend? Feel free to convince me otherwise with facts rather than opinions, as I am trying to change my opinion. The other alternative I found is a Peavey IPR2 3000 which a lot of people seem to prefer as an "better" alternative, but again opinions. I am probably overthinking thimgs, as usual, but I like the chance to understand my decisions, as my knowledge is limited.
davewantsmoore Posted December 6, 2018 Posted December 6, 2018 (edited) 11 hours ago, Primare Knob said: Behringer is a good amp Behringer has a bit of stigma caused by low price products and copying of IP. The reality is that the other brands you list, while more well known, don't have necessarily better products ..... and model to model this could vary a lot. You posted a link before to a tear down of amps - pages like this are good to see what you really get in a specific model. The sort of page which understands that it's the value of capacitance, as opposed to the brand or price of the capitance, which is the more important thing. Buy one and try it .... if you are unhappy send it back, or sell it on for a small loss. Edited December 7, 2018 by davewantsmoore 2
Wozza_Lee Posted December 7, 2018 Posted December 7, 2018 Over on AVS forums they have done a full set benchmark testing of the behringer inuke amps 1
Primare Knob Posted December 8, 2018 Author Posted December 8, 2018 Parts are ordered. 2x Dayton RSS390HO and 1X Behringer iNuke6000.Parts that are still on the list:Speakon connecters, external fan modification, timbers.I am thinking about doing a 9mm MDF and 9mm plywood combination with the plywood for externally for the looks.Forgot to ask, but does a subwoofer needs passive adjustments as I ordered the amp without any DSP. 1
davewantsmoore Posted December 8, 2018 Posted December 8, 2018 If you're going to bother laminating two bits of wood.... then go a bit thicker on at least one. Especially if you are not planning crazy 3d bracing.
Primare Knob Posted December 8, 2018 Author Posted December 8, 2018 I was planning to use this as an example,https://www.parts-express.com/dayton-audio-15-ultimax-subwoofer-and-cabinet-bundle--300-709718mm MDF and 6mm Plywood?Does the box needs some internal stuffing? And I was thinking on glueing and screwing the internal box and glue/laminate the outer shell which has nice 45 degree edges.
Nada Posted December 8, 2018 Posted December 8, 2018 1 hour ago, Primare Knob said: ......Forgot to ask, but does a subwoofer needs passive adjustments as I ordered the amp without any DSP. Nice drivers. Regarding crossover and equalisation can you change your order and get an amp with DSP or are you wanting to use something like a miniDSP?
Primare Knob Posted December 8, 2018 Author Posted December 8, 2018 Nice drivers. Regarding crossover and equalisation can you change your order and get an amp with DSP or are you wanting to use something like a miniDSP?I am using DSP at the source, but that only works for both subs at the same time. I was trying to avoid another layer of DSP but forgot that the individual subs might need some adjustments.I bought the amp on eBay from DJ City.
davewantsmoore Posted December 8, 2018 Posted December 8, 2018 3 hours ago, Primare Knob said: 18mm MDF and 6mm Plywood? Yep... something like that. 3 hours ago, Primare Knob said: Does the box needs some internal stuffing? No 3 hours ago, Primare Knob said: And I was thinking on glueing and screwing the internal box and glue/laminate the outer shell which has nice 45 degree edges. Screws can help it go together a lot easier, and means you might not need so many large clamps. If you are going to laminate the outside skin after you have built the box .... then it can be a challenge to get enough and even pressure. 1
almikel Posted December 9, 2018 Posted December 9, 2018 (edited) On 08/12/2018 at 1:19 PM, Primare Knob said: Does the box needs some internal stuffing? 21 hours ago, davewantsmoore said: No agreed. Longer answer there's an interesting article over on Data Bass testing subs with/without stuffing https://data-bass.com/data?page=content&id=79 Stuffing is more of a requirement for woofer/mid boxes that are large enough, and run high enough to have modes generated inside the box - modes will be generated if the longest dimension of the box > wavelength/2. If you ran your subs as high as 100Hz --> wavelength = 3.44m and wavelength/2 = 1.72m...and all the internal dimensions of your subs will be smaller than that. Stuffing does make the "apparent" volume a little large, but too much can reduce efficiency... ..,as Dave says it's not needed for your application. On 08/12/2018 at 11:55 AM, Primare Knob said: does a subwoofer needs passive adjustments not if you're going to do Xover and EQ elsewhere using DSP - which I would strongly recommend...a passive Low Pass Xover at 24dB/octave for the sub requires big caps and chokes and can't be tweaked for frequency without buying new components. Much easier to implement with DSP, which will provide EQ also. On 08/12/2018 at 1:24 PM, Primare Knob said: I am using DSP at the source, but that only works for both subs at the same time. I was trying to avoid another layer of DSP but forgot that the individual subs might need some adjustments. Is the iNuke available with or without DSP? If that's the case, and it wasn't too late to change your order, I would do so (edit - buy the amp that had DSP). It just provides more flexibility down the track, where you may find you want to apply different EQ to each sub... ...free tools like Multi Sub Optimiser require the ability to tweak EQ and delay per sub...but you could implement something like MiniDSP later. 21 hours ago, davewantsmoore said: If you are going to laminate the outside skin after you have built the box .... then it can be a challenge to get enough and even pressure. laminate boxes can be tricky...the lazy DIYer in me says if you like the plywood look, just use 32mm MDF and veneer it afterwards... but looks is something I'm not highly qualified to advise on - I just use Duratex these days (it's a black ripple look), it's very good at hiding lots of things and looks great IMHO. cheers Mike Edited December 9, 2018 by almikel clarification 1
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