Punisher plots

doober wrote: The amp levels were set for the first sweep then not changed for the rest as more cabs were plugged in. This means the total impedance lowered, 8 - 4 - 2.66 - 2 ohm, and therefore total power input rises with each cab added, power per box drops. I though this was the most realistic way to compare plots rather than trying to make it a constant power at each sweep.

In fact power per box doesn't drop if not driven to maximum (clip). The graphs show it too, roughly 6dB more for each doubling of cabs, apart from the respons nicely flattening out to the low side, the more cabs play together.

doober wrote: I'm not sure why there are those notches on the single cab and three cabs measurement. Any comments?

Seems logical that 1 or 3 has a notch and 2 or 4 don't if they were on their side. I don't know if you measured only 1, 2 or 3 cabs connected in a stack of 4 or with 1,2 or 3 placed on their own for each measurement. Might be intresting to see how dips would occur (or less or not at all) if the cabs were placed with the mouth(s) to the soil or floor, meaning the underside of the cab(s) down. The majority of waves are found in that part of the mouth and as they 'see' an open space when exitting the horn or a cavity from another cab that's not connected to the amplifier, they will behave different than when they 'see' a mirror from the soil/floor or another cab that has the same waves propagating and adds the SPL, instead of disturbing it in some way. For one cab it's a dip that goes down about 7dB around 75Hz and that's a serious problem for a bass cabinet. Two cabs still behave somewhat funny, but less obvious than one. Three cabs have the same thing going on as one, less dip, but not as smooth as it should be or could be. At some points three cabs go a tad over the response of four and even if it's not in the area the cabs will be used in, it's an indication that this kind of placement on his side has issues. From four cabs on and more, the erratic behaviour is largely gone.
On a side note let me tell you that I had the same thing going on with KF940 cabs I used about 10 years ago. Stacks of four or more with mouths coupled, worked great, but three had to be with mouths down to the floor or the 'punch' was gone. I never took the time to measure it up, as I didn't find it exiting to know precisely how much and at what frequencies the trouble occured. I knew what caused it and worked around it. Some folks suggested to EQ it out, but this kind of problems can't be EQ'd out, only destroy speakers with no significant effect on respons whatsoever. The placement is the problem, not the response of the cabinet(s).


Edited by Peter Jan - 16 December 2009 at 11:07pm

Ibex wrote: What would you recommend for stacking two cabs? Bottom to bottom of each cab lying on their sides or both with their bottom against the floor ?

darkmatter wrote: Kinda raises the question of whether these can be used up to ~140hz when in a larger stack. People report honk at 120hz and that's pretty evident in the graphs for 1 and 3 cabs but not in the 4 cab response.

How much power your giving them dos not really matter if your not measuring spl, and if you haven't got calibration kit and expensive mics i dont think there is an awful lot of point in measuring SPL. it gives a good idea of frequency responce though,

thease plots seem to tally well with the plots i took in the summer, theres a couple of dips on mine but they came with every speaker, so proximity of walls would account for that.
http://forum.speakerplans.com/got-a-lot-of-plots-eh-wot_topic28237_post281115.html?KW=plot#281115


Seem to run smooth to about 42-43HZ then drop off sharply.

Anyway, nice one Doober for taking the time to do this!


Edited by Timebomb - 17 December 2009 at 1:27pm

doober wrote: Shortly after posting the plots I realised what was causing the dips. For the plot of one box I had an unpowered box sat on top. For the plot of 3 boxes I had a stack of four, one unpowered. It would seem that the unpowered box is sucking a bit of the energy from the powered one at those points.

Yeah 3 seem to sound a lot smoother than 2, i think there totally usable in 3s, what  software were you using?