Magic Matt Posted September 7, 2014 Share Posted September 7, 2014 (edited) I've moved, and as a consequence, I actually have some space to build the DIY cabinet I wanted to make a year ago! Hooray! My plan is to start simple - I'm thinking good quality driver, simple cabinet, make it look nice, and enjoy it. If it works well, I can always think about building a better one, and transfer the driver. It'll be a simple box, rectangular bass port, 130 litre, tuned to 25Hz (hopefully), built with 15mm void-free ply, braced, and lined inside with 26mm dacron. Fingers crossed! However, I don't really want to build a combo (although that's what I'm still using now), and the idea is not to have to take my existing heavyweight amp. I need an amp head! I like fairly deep bass tones - I mostly play blues and soul, so it's not thunderous loud rock. I would like a head that's going to make the most of that driver, and give me a nice wide range of bluesy, jazzy tones to play with, dipping into the odd bit of funk/slap or rock for the odd number we do. My current Peavey 115S combo seems to manage pretty well across the board for this, but I'm hoping I can at least match it if not better it with my first build (too ambitious?) I want to spend as little as I can get away with, and I'm happy to buy second hand, but not sure what to look for. Recommendations please? Edited September 7, 2014 by Magic Matt Quote Link to comment Share on other sites More sharing options...
Bill Fitzmaurice Posted September 7, 2014 Share Posted September 7, 2014 [quote name='Magic Matt' timestamp='1410084748' post='2545885'] It'll be a simple box, rectangular bass port, 130 litre, tuned to 25Hz Recommendations please? [/quote]How did you arrive at that? The C2515 models to the flattest possible response in 412L tuned to 33Hz. That's silly large, of course, but points out why one should think thrice about using the C2515. It can work in 130L, but you wouldn't tune it at 25Hz. 40Hz is the lowest you'd want to go. 25Hz would make the port unmanageably long, and would cause a serious loss of maximum output, while there's no benefit to be gained from tuning that low. Quote Link to comment Share on other sites More sharing options...
Magic Matt Posted September 7, 2014 Author Share Posted September 7, 2014 [quote name='Bill Fitzmaurice' timestamp='1410094346' post='2546001'] How did you arrive at that?[/quote] Well unless I'm using it wrong, WinISD.... I've since been playing with it and now I have a 120L box (50cm wide, 80cm tall, 30cm deep) and it seems to say that to tune to 30Hz I'd need 4 vents, 10cm wide, 3cm high, and 28cm deep (most of the depth of the box)... hence I thought I could just put a false bottom in with a 2cm gap at the back and a hole at the front for the bass port, and just use some 32mmx32mm batons to split the port into 4 channels. Am I wrong? The only reason I'm aiming for that sort of size is that I know it can fit into the boot of my car without having the seats down, which is extremely useful. Quote Link to comment Share on other sites More sharing options...
Bill Fitzmaurice Posted September 7, 2014 Share Posted September 7, 2014 Why tune so low? Maximum output demands, even for a low F# six string, lie between 40 and 70Hz, so you should be looking at the maximum SPL chart to find the tuning that gives the best result in that range. Tuning lower than 40Hz robs you of maximum output in the 40-70Hz bandwidth, and it makes the cab larger than it needs to be. If you have a 4 string you should be tuning even higher, 45-50Hz. Quote Link to comment Share on other sites More sharing options...
Magic Matt Posted September 7, 2014 Author Share Posted September 7, 2014 (edited) [quote name='Bill Fitzmaurice' timestamp='1410121810' post='2546410'] Why tune so low? Maximum output demands, even for a low F# six string, lie between 40 and 70Hz, so you should be looking at the maximum SPL chart to find the tuning that gives the best result in that range. Tuning lower than 40Hz robs you of maximum output in the 40-70Hz bandwidth, and it makes the cab larger than it needs to be. If you have a 4 string you should be tuning even higher, 45-50Hz. [/quote] I freely admit this is because it's my first time trying to build a cab, so I'm not that sure of what I'm doing. I thought I was supposed to be trying to eliminate the "hump" on the gain chart? I've obviously confused myself somewhere... point me to something that I should be reading? Edited September 7, 2014 by Magic Matt Quote Link to comment Share on other sites More sharing options...
Magic Matt Posted September 7, 2014 Author Share Posted September 7, 2014 Ok, so I downloaded WinISD Pro and tried to put the parameters in direct from the spec sheet.... same as I had in WinISD... http://www.eminence.com/pdf/Basslite_C2515.pdf This happens... [IMG]http://i.imgur.com/2woU7wn.jpg[/IMG] ...oh. Bugger. Now I don't know what to do. Quote Link to comment Share on other sites More sharing options...
Bill Fitzmaurice Posted September 7, 2014 Share Posted September 7, 2014 (edited) [quote name='Magic Matt' timestamp='1410126455' post='2546474'] Ok, so I downloaded WinISD Pro and tried to put the parameters in direct from the spec sheet.... same as I had in WinISD... [url="http://www.eminence.com/pdf/Basslite_C2515.pdf"]http://www.eminence....slite_C2515.pdf[/url] This happens... ...oh. Bugger. Now I don't know what to do. [/quote]That's because WinISD is more accurate in the spec calculation than Eminence, going to more decimal places. Only put in as many specs as required, let WinISD calculate the rest. That means Qes,Qms,Vas, Fs, Re, Le, Sd, Xmax and Pe. As for eliminating the hump, you do that by using the correct size cab. Since you're undersizing the box you'll have to live with the hump. Edited September 7, 2014 by Bill Fitzmaurice Quote Link to comment Share on other sites More sharing options...
Magic Matt Posted September 8, 2014 Author Share Posted September 8, 2014 Ok... but if tuning the cab lower gets rid of the hump, and doesn't seem to make a huge difference to SPL on the graph... why is that bad? ...can't I just turn the amp up a tiny bit more to compensate? (I expect I'm missing something crucial here, but I don't know what) Quote Link to comment Share on other sites More sharing options...
Balcro Posted September 8, 2014 Share Posted September 8, 2014 Tuning the cab lower will only reduce the hump but it will not be eliminated. Reducing the hump will make it easier to re-balance the sound via the amp or bass eq. Cut the bass and boost the mids. However, tune too low and and the already weak low-bass power-handling will suffer drammatically. Give yourself a shock by clicking on the (Transfer function magnitude / SPL menu) button and selecting maximum power! There's more to tuning than simply achieving the highest SPL. Do as Bill suggests in post #7 and just enter the parameters he has listed; winISD will do the rest. Then save it. Likewise, when it comes to adjusting the response, tune it as Bill suggests. Balcro. Quote Link to comment Share on other sites More sharing options...
Bill Fitzmaurice Posted September 8, 2014 Share Posted September 8, 2014 [quote name='Magic Matt' timestamp='1410136424' post='2546529'] Ok... but if tuning the cab lower gets rid of the hump, and doesn't seem to make a huge difference to SPL on the graph... why is that bad? ...can't I just turn the amp up a tiny bit more to compensate? (I expect I'm missing something crucial here, but I don't know what) [/quote]Look at the Maximum Power and Maximum SPL charts. Quote Link to comment Share on other sites More sharing options...
Magic Matt Posted September 8, 2014 Author Share Posted September 8, 2014 Now I have WinISD Pro working, it makes more sense! The normal WinISD doesn't have Maximum SPL etc. so the only thing I had to look at was what thisseems to call "Transfer function magnitude". I can see how the tuning is affecting the Maximum SPL now - makes far more sense! So my bottom E (which in some blues numbers is played a lot) is 31Hz fundamental. Having done some more reading that seems to be saying that the main amount of energy is at 2x fundamental (62Hz) with the "definition and punch" being somewhere up in the low kHz range. I sometimes tune down to D (28Hz) so that would mean most energy at 56Hz.... alarmingly close to the 45Hz-50Hz you recommended. I then played around with the tuning, looking at cone excursion and Maximum SPL, and it seems as if 38Hz isn't that much different to 47.5Hz overall, except the 38Hz produces more at the fundamental for the bottom E. [IMG]http://i.imgur.com/Po4sHgl.png[/IMG] [IMG]http://i.imgur.com/ibV59T3.png[/IMG] Is it just the slightly higer Maximum SPL that makes the higher Hz a better choice, or would the 38Hz be better? Also, looking at the somewhat alarming cone excursion graph, should I be putting a passive highpass filter on the speaker to protect against any very low frequencies (thud from an amp etc?) ? Quote Link to comment Share on other sites More sharing options...
Bill Fitzmaurice Posted September 8, 2014 Share Posted September 8, 2014 Low 'E' is 41 Hz. Most amps have a high pass filter built in to prevent over-excursion below 40Hz. Maximum output above 50Hz is what matters. Quote Link to comment Share on other sites More sharing options...
Magic Matt Posted September 9, 2014 Author Share Posted September 9, 2014 Ok (feel free to call me an idiot any time you like, lol) ... at least I'm trying though! So, I'm looking to get the most output I can over 50Hz, but avoid getting the 41Hz low E dropping too far down that steep slope, otherwise it will be much weaker than the other notes... yes? That's making more sense... as now I'd be tuning the box to 46Hz, which is as high as I can go before the 41Hz starts to massively drop off... [IMG]http://i.imgur.com/O3dGVIr.png[/IMG] ...am I making a bit more sense? Quote Link to comment Share on other sites More sharing options...
Phil Starr Posted September 9, 2014 Share Posted September 9, 2014 I know Bill and I have been known to fall out over just how difficult it is to design a 'successful' cab but there are a lot of things to think about, and to learn. Google for an online signal generator, plug in a decent set of headphones and listen to a 1000Hz signal as loud as you can bear it then change the frequency to 41 Hz. You probably won't hear it although it will be at the same volume as the 1kHz signal. You'll also be amazed at how low a tone it is, we almost never hear anything that low because our ears aren't really designed to work down there. Fundamental isn't really that important, once you play with drums and guitar playing too it is even less so. Now think about the wavelength of the sound, if the floors and walls are within half a wavelength they are going to reflect the sound and it will be like having extra speakers and the bass will be too loud, If the room is small you can't really propagate the bass because the room is shorter than the wavelength, if it is big then because the room is going to be a wavelength or two long at certain frequencies you are going to get standing wave resonances set up. Mostly real bass is just a problem in most rooms. The modelling software concentrates on the low frequencies and there is a tendency for us to obsess over them as a result. Concentrate on getting a smooth response and keeping excursion in limits and you'll get a better cleaner sound. The whole point of the port is that it gives you a bit of extra output at around the frequency the speaker naturally cuts out, put it too low and it might just as well not be there because it will never make a sound, too high and it will unload the speaker meaning real excursion problems if you do put real bass at high power through it. FWIW I think it is great you want to do this, you are going to learn loads and you'll almost certainly end up with a usable speaker first time and a better one in subsequent builds, one day you will be as boring as i am Quote Link to comment Share on other sites More sharing options...
Magic Matt Posted September 9, 2014 Author Share Posted September 9, 2014 Not boring at all - I'm finding it all fascinating (even if I'm not any good at it yet). Quote Link to comment Share on other sites More sharing options...
Bill Fitzmaurice Posted September 9, 2014 Share Posted September 9, 2014 [quote name='Magic Matt' timestamp='1410264681' post='2547594'] So, I'm looking to get the most output I can over 50Hz, but avoid getting the 41Hz low E dropping too far down that steep slope, otherwise it will be much weaker than the other notes... yes? [/quote]No. While the low E note has a fundamental of 41Hz most of its content is in the harmonics. For reference, a Fridge f3 is 58Hz. No one complains about how it handles the low E. Quote Link to comment Share on other sites More sharing options...
Magic Matt Posted September 9, 2014 Author Share Posted September 9, 2014 I've never tried to use a fridge as a speaker cab... if I ever joina punk band I'll give it some thought! Got me rethinking now... 2 x 12" might be better? - smoother overall response in a small cab than a single 15"? [IMG]http://i.imgur.com/YuSx3sM.png[/IMG] Quote Link to comment Share on other sites More sharing options...
Balcro Posted September 9, 2014 Share Posted September 9, 2014 In your last post (with the two graphs) You've set the input to 200 watts. Without changing anything else, click on the "maximum SPL" tab and from the drop down menu select "Cone excursion". You've exceeded xmax by 1.5mm. at about 77Hz! Keep that up for long and you won't have an undamaged Basslite. All the features and parameters are there to be married together. They're listed for a purpose. Yes, it's loud, but for how long. Balcro. Quote Link to comment Share on other sites More sharing options...
Bill Fitzmaurice Posted September 9, 2014 Share Posted September 9, 2014 I'd always go for two twelves over one fifteen, and for that matter two 1x12 over one 2x12. If you're thinking of a course change you should consider my Simplexx 12, as all of the R&D is done, as is the forty years of experience that went into that R&D. You just have to put it together. Quote Link to comment Share on other sites More sharing options...
Magic Matt Posted September 9, 2014 Author Share Posted September 9, 2014 (edited) I had a look at - [url="http://billfitzmaurice.info/Simplexx.html"]http://billfitzmauri...o/Simplexx.html[/url] - sorry if I'm being an idiot again, but I couldn't see what drivers I'm supposed to buy for them...? I'm basically trying to stick to Neo drivers simply because I live on the first floor and have to carry the things up and down stairs all the time. Is there much cost difference in building two 1x12" rather than one 2x12" ? ...and the only power tools I have take batteries, so the idea of the plans being simple is VERY appealing! lol Edited September 9, 2014 by Magic Matt Quote Link to comment Share on other sites More sharing options...
Bill Fitzmaurice Posted September 9, 2014 Share Posted September 9, 2014 [quote name='Magic Matt' timestamp='1410301280' post='2548088'] I couldn't see what drivers I'm supposed to buy for them...? [/quote]None, until you have the plans in hand and are able to weigh the options. There's very little difference in the cost of two 112 versus one 212, the only major one being the need for more jacks with two cabs. Quote Link to comment Share on other sites More sharing options...
Magic Matt Posted September 9, 2014 Author Share Posted September 9, 2014 [quote name='Balcro' timestamp='1410292765' post='2547974'] In your last post (with the two graphs) You've set the input to 200 watts. [/quote] Yes, I forgot to set it back to 100 watts before I took the screen shot, lol However, at 200 watts, the 2x12" setup actually copes, which is pleasantly surprising. [IMG]http://i.imgur.com/wRrexwF.png[/IMG] Quote Link to comment Share on other sites More sharing options...
Magic Matt Posted September 9, 2014 Author Share Posted September 9, 2014 [quote name='Bill Fitzmaurice' timestamp='1410301793' post='2548095'] None, until you have the plans in hand and are able to weigh the options. There's very little difference in the cost of two 112 versus one 212, the only major one being the need for more jacks with two cabs. [/quote] Well the amount of learning in the plans is probably worth their weight in gold at this point, so I shall order some right now! Quote Link to comment Share on other sites More sharing options...
Marvin Posted September 10, 2014 Share Posted September 10, 2014 (edited) As a first build, Bill's Simplexx cabs are a great starter. It's about as straightforward as you can get I'd say. The plans are very detailed, got great tips and advice on the build process and provide a number of driver options to suit taste and/or budget. Edited September 10, 2014 by Marvin Quote Link to comment Share on other sites More sharing options...
Magic Matt Posted September 10, 2014 Author Share Posted September 10, 2014 Yes, I've read through the Simplexx 12 plans a few times now - might actually be starting to sink in... I'm very tempted by the two 1x12" route, rather than a single 15", because I can build them one at a time, which means the expense can be spread out a bit too. Quote Link to comment Share on other sites More sharing options...
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