davewantsmoore Posted March 26, 2016 Posted March 26, 2016 transient response This is a very often poorly defined term. What exactly do you mean when you think of "transient response" ? So would transient response around resonance suffer in the smaller enclosure (assuming eq'd to same FR). Still trying to get my head around this :-/ No. If two speakers have an identical frequency response then by definition they also have an identical "transient response". (the frequency response and 'transient response' are simply two different ways of viewing the same information) The larger box will present a different load to the amplifier, and you can see this in the electrical impedance curve and the amplifier load VA curve in post #54 The larger box, will allow more cone excursion at low frequencies for a given input power .... and hence make more bass at these frequencies
Neo__04 Posted April 8, 2016 Author Posted April 8, 2016 (edited) Hi again, Just popping back in with some updates. Finally got around to starting my build. Been hectic at work and havent had the time or motivation to get started. So... Considering its my first set of speakers, first time using a router for this sort of work. They front of the speakers came up perfect. Speakers fit perfect, perfect cutout, perfect rebate. Couldnt be happier. So far i've glued the top,bottom and sides together. Tonight i glued the front on. So hopefully over the next few days i should have them assembled and i can do some testing. A couple of pics attached. Edited April 8, 2016 by Neo__04 2
Neo__04 Posted April 11, 2016 Author Posted April 11, 2016 Im back and I need some help. I have assembled the first speaker, screwed on the back panel for the moment while testing. Hooked up via a minidsp for the crossover. Running of a Behringer UCA202 usb Dac Taking some measurements in REW with a calibrated Umik-1 mic. Mic is 1m away from speaker, pointed level at tweeter. These speakers have 0 bass. The box works out at around 21.5 litres not taking into account the drivers. There is no stuffing inside at this stage. For my testing, they are around 81db at 109hz, then they drop to around 77.5db by 100hz, They are 10db down by 92 hz. No high pass filter used for the testing of the bass. Unibox says FB is arond 56.5hz, F3 78.7hz I'll attach a graph. Surely this seems wrong? Any advice would be great. Thanks heaps
davewantsmoore Posted April 11, 2016 Posted April 11, 2016 (edited) Surely this seems wrong? Yes. The rolloff is much steeper than expected. This isn't caused by the box size or absence of stuffing. Is the "screwed on back panel for testing" air tight? It could be a small air leak causing this. Otherwise? I assume both drivers have the same behaviour? :/ Edited April 11, 2016 by davewantsmoore
Neo__04 Posted April 11, 2016 Author Posted April 11, 2016 I havent got the other speaker together yet as im waiting for speaker terminals. Its definately not air tight, i only put a screw in each corner while i was stuffing around learning and measuring. Well thats my stupid fault then, So hopefully i can assume thats all it is, its just very leaky
Sub Sonic Posted April 11, 2016 Posted April 11, 2016 (edited) Is the box completely air tight as DWM mentioned? If so, could you possibly post an impedance plot of the bass speaker in the box? SS Edit: oops I just saw your post above :-) Edited April 11, 2016 by Sub Sonic
Neo__04 Posted April 11, 2016 Author Posted April 11, 2016 Yeah its my fault, lol. Ok, so im happy it sounds good apart from the lack of bass sub 100hz. Im happy to glue it up and seal it. Before I do, is there a general recommendation on how to stuff/fill a speaker like this? Once i work that out, ill seal it up and test it out again
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