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a load of newbie questions + martin audio Q's |
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teeth 
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Joined: 05 July 2021 Status: Offline Points: 566 |
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 Topic: a load of newbie questions + martin audio Q'sPosted: 05 July 2021 at 11:13pm |
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hi there, firstly, massive respect to every one of you, you are dead friendly, and all know your stuff. i'm really new to this so missing some basic principles, perhaps you can help. don't have anyone to show me this stuff, i'm just feeling my way around! i feel like these are maybe silly questions, i'm starting to understand power and ohms and the rest of it, but i'm sure there's some bits i'm missing. i've just picked up a pair of Martin F12, i want to build a little martin PA. i have heard martin stuff before and i really like the way it sounds. it's not too big too. i see they are 300w with 1200 peak, so i can power two with my 900w amp, right? it's a studiospares 900+ trojan. or do i have to have an amp that's rated higher than the peak? for 2 speakers, that would have to be over 2000w, right? i will now need to get some subs, it seems like the S12 or S15 will be best. (any opinions on those are welcome!) they are 500w, or 1000w peak, so i need to get a minimum of 1000w amp for these, but probably a 2000w one to be safe? i see they have built in cross overs, does this mean that i don't need to get a crossover? the F12 is "2kHz passive" and the subs are "120Hz passive / active" one last question! i see that at the top of page 9 here, there is a diagram showing the amp going in to the sub, and then chained out to the top. https://martin-audio.com/downloads/archive/userguides/BKLINE_EN.pdf is it possible or safe to do that with one amp? i have seen amps that go up to 6000w! could you do left and right subs and tops off one amp in that case? is it better to have an amp for the subs, and an amp for the tops? ok, think that's it... wish there was a guide or a book or something about all of this stuff, i'd eat it up! thanks in advance! teef
Edited by teeth - 05 July 2021 at 11:14pm |
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itskabini
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Joined: 03 April 2019 Location: London Status: Offline Points: 49 |
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Posted: 06 July 2021 at 9:57am |
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total wattage of an amp isn't the important number, you need to look at the ohm rating of the speakers, and see what each channel of the amp can deliver into that ohm rating When looking at subs, you're right that it's best to get stuff from the same range if possible, and I'd also look at the S18, and maybe stay away from the s12. Two S12s is likely to be a lot quieter than you're two F12 main speakers. I think the best pairing would be with two S18 subs. Although this does depend on what kind of music you want to play, and what your priorities are for things like weight. Two S15s would probably be OK too. In any system there needs to be something called a crossover or LMS (loudspeaker management system) to divide the frequencies up between the main speakers and the subwoofers. Normally this will be external and in a special device like a behringer ultradrive or DBX driverack, however the martin subs have a switch on the back which enables a high pass filter on the link output when set to "passive" This means you can use just one amp and no external crossover, however you will need two subs (one for left and right) If you want to go this way you'll probably need to sell your amplifier and get one more powerful one, as subwoofers take a lot more power than main speakers. Martin say this configuration is a 4 ohm load, so you'll need an amplifier that's able to do about 2000W into a 4 ohm load and with 2 channels (something like a Behringer nx6000d or a t.amp e-1500). Generally you want your amp to be able to deliver about the "peak" rating of the speakers If you're only going to ever want 2 subs and two tops, then using the built in filters on the subs with a big amplifier is probably the way to go, but if you think you might want to expand the system one day, then I'd recommend to get an external crossover and manage it all yourself there. Although you'll still need an amp like I mentioned above to run the subwoofers. |
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teeth
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Posted: 06 July 2021 at 11:27am |
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thanks itskabini, i appreciate you taking the time to type that! maybe it will be cheaper to get 2x smaller amps than one beefy one? then i can have one do the left, and one do the right. and i can utilize "bridge mode" to fully utilize the power of the amp. so maybe 2x1000w amps would do the job? if not definitely 2x2k or 2x3k. so am i correct in saying that the S15/18 series DONT need a crossed over input, but the F series do? does that 2kHz passive x-over actually do anything then? what would happen if i just plugged in an amp with no x-over? thanks again. more reading to be done.
Edited by teeth - 06 July 2021 at 11:29am |
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itskabini
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Posted: 06 July 2021 at 12:04pm |
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Bridge mode doesn't always help out. If we think of the situation with your Studiospares amp, in bridge mode it can deliver 900W into 8 ohm, although only on one channel, or it can deliver 300W on two channels into 8ohm or 450W on two channels into 4 ohm. Adding two 8 ohm speakers to one channel makes it a total 4ohm load, you can look up how resistors in parallel work to find out more about this. This means that if you bridged your amp, and connected it to both a sub and a f12, you'd be attempting to drive a 4 ohm load with something that is only meant to power an 8ohm load.
Also if you only have one sub and intend to use the built in crossover, you won't have a stereo signal anymore The f12s have two drivers in them, but you only need to supply it with one signal, the internal crossover will split that signal into the signal for the tweeter (over 2.2kHz) and the woofer (below 2.2kHz). If you just plug the F12s straight into your amp it will work fine but have not much bass due to the lack of a subwoofer. You need something that will split up the frequencies so that the low ones come out of the sub and the high ones (over about 120Hz) come out of the F12s Generally It's best to have one amp that deals with your tops, and one that deals with your subs. As what you need from each kind of amp is a bit different. You could in the short term run two subs and two f12s off just your studiospares amp, with one of each connected to each channel. but it wouldn't be very loud. What's your approximate budget for putting the rest of the system together? and what is your "end game" system as that will make it easier to decide what to get in the meantime
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teeth
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Posted: 06 July 2021 at 12:11pm |
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thanks for all of that :) "end game" is a portable and decent sounding PA. so i'm thinking 2xF12, 2xS15, then two amps in a rack would be great. so i'm really leaning towards doing the 4ohm chaining set up to be honest! no crossover = 1 less thing to carry and buy, haha. budget... not sure. i think i can find a pair of S15's for £500, and say another £300 for amps. seems doable from what i've seen, those behringer NX's are about £150. https://www.ebay.co.uk/itm/255043339491?epid=5039167370 i'm thinking i could get two of those, bridge mode, one for each side? seems like a very cost effective solution! thanks for explaining the crossover in the F12, that makes sense.
Edited by teeth - 06 July 2021 at 12:23pm |
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itskabini
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Posted: 06 July 2021 at 12:39pm |
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The behringer ones aren't known for being the best sounding but they are definitely good value. If the aim is to reduce things carried, I think one nx6000 can do the same job as two nx3000. as the nx6000 has 2 channels that can each do 3000W into 4 ohm. There's a version called the nx6000D to which has some EQ and limiting that could be useful for learning more about how soundsystems work in the future. I think it is £360 with the regular nx6000 being £300. The limiters in it will be useful for making sure you don't blow any of your speakers in future. Keep hold of the studiospares amp too, as using that for tops and the behringer on bass with an external crossover will likely sound better than using just the behringer amp and the crossovers in the subs.
Personally I'd aim for s18 over s15, especially for dance music, as they'll go a fair bit louder and deeper. Oh and make sure the switches on the subs are set to "passive" when you want to use the crossover in them, or you might risk blowing out your tops. |
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itskabini
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Posted: 06 July 2021 at 12:40pm |
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Actually, I've just had another idea, if your're not worried about stereo imagine, you could use one channel of the nx6000d for subs and another for tops using the active crossover built into the behringer, that could give you a bit more flexibility and let you set proper limiters.
There is a lot of people saying that the behringer amps don't sound good for tops, but as a way to get started it should be Ok, until you can afford something better. Edited by itskabini - 06 July 2021 at 12:42pm |
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teeth
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Posted: 06 July 2021 at 1:40pm |
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cool, thanks for that. i feel you on the 18's but they are over double the price of the 15's, so think it will have to be 15's for now. will look in to all this amping stuff, right now i'm leaning towards doing the one or two amps doing the left/right chaining thing (what's this called by the way?) because i can maybe get two less powerful amps (2x1000w?) and then upgrade down the line. i'll keep an eye out for a big 6000w thing though. that would be perfect. having said that, there is a NX3000 and NX1000D on ebay, that would do my subs and tops respectively...? EDIT: no, they are only 4ohms out!
Edited by teeth - 06 July 2021 at 1:41pm |
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itskabini
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Posted: 06 July 2021 at 2:20pm |
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Yeah i guess a lot of people are wanting the 18s over the 15s
two less powerful amps normally isn't cheaper than one large one. the nx6000d is £360 new where as the nx3000d is £260 on thomann including taxes. If you buy new you'll at least get a warranty of some kind. One channel is left or right, so one channel will be doing left sub and left speakers, and the other channel doing the right sub and right speaker. one top and sub on each amp channel will present a 4 ohm load which is fine. the nx3000d has 2 channels that can each do 900W into 4 ohm where as the nx6000d can do 3000W into each channel. To start with just get the 15 subs and use your current amp, then upgrade later on if its not loud enough. An amp that isnt powerful enough doesn't cause any problems but will just make the speakers quieter
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teeth
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Posted: 06 July 2021 at 2:25pm |
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thanks, that's really good to know. appreciate all this advice, will let you know how i get on!
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Earplug
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Posted: 06 July 2021 at 3:55pm |
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Yes, the few dB you will lose is not that important. Very often that is lost with overheating the speaker and subsequent power compression. The very important thing when using any amp, especially if you don't have headroom, is not to hit the clip. Make sure that you are sending a clean signal to the speakers. And especially with the cheaper Class D stuff. |
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Earplugs Are For Wimps!
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Bams
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Posted: 06 July 2021 at 4:15pm |
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Regarding cheaper class D amps, if possible, buy new or young ones with warranty. there isn't a lot you can do on them when they break down and are not always as durable as old iron.
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itskabini wrote: