Square speakers affect on small room freq response!

[wm]

hi,

i have a small home studio with fairly difficult acoustics. the room has been treated with about 8x 4" rockwool slabs and a few 1" slabs. this improved the response a lot but still left many problems mainly in the form of boomy low mids (200-500hz). a few months ago i decided to try new monitors and still cant believe the difference its made all around the monitoring spot freq response. i previously had square speakers (mackie hr624) and swapped to genelec 8030A with their MDE curved enclosure plus sub. this instantly made a massive difference to the problems i was having in the low mids. which i can only assume is a result of the curved enclosure (plus iso pod) over the regular square one of most other monitors?

i thought others with difficult acoustics may be interested in this massive improvement in my already treated room, and maybe some experts could give their views/explanations, since i dont often see much emphasis on this area, perhaps since there is only one (i think) monitor company making curved enclosures.

heres a 20-20 sweep of the response at mix postition 624 (top) vs 8030:



the difference below 90hz is due to deciding to go for a separate sub unit over the 8040s lower extension, which has allowed me to position and level it to get flatter response than posible solely with speakers in my room. this response was done a few months ago when i had both speakers and set them up the same, its since been improved though (100-200hz higher, 200-500hz lower) by moving the monitors higher and repositioning some treatment.

anyway i took lots of readings with my ECM8000 all showing the huge monitor change improvement, and audibly its meant ive had to remix many things, at last i can rely fully on my ears not references.

if this improvement is because of the curved enclosure then i assume it would be far less in larger rooms, where the reflections have a larger volume to bounce round.

my studio room:





(old pic, speakers arent on cds anymore, and werent for testing above )

thanks,

[Ethan Winer]

i have a small home studio with fairly difficult acoustics. the room has been treated with about 8x 4" rockwool slabs and a few 1" slabs.

That's a decent sized room, and adding another eight 4-inch thick traps in any remaining corners will only help.

> i previously had square speakers (mackie hr624) and swapped to genelec 8030A with their MDE curved enclosure plus sub. this instantly made a massive difference to the problems i was having in the low mids. <

I can attest that the 624s are very flat, though their 49 Hz low frequency limit hides deep bass problems in the room. When you add a sub you introduce yet another chance for waves to combine in and out of phase (peaks and nulls) in the air. I have 624s in my living room home theater, with a top of the line SVS sub, and my response is amazingly flat. But I also have 40 traps in that room!

> which i can only assume is a result of the curved enclosure <

Doubtful. Really, the best solution is more bass trapping. As always.

--Ethan

[wm]

hi ethan,

thanks for your response. but you seem to be denying the affect ive seen from changing the monitors? i know the mackies are ruler flat (even more so than the genelecs +/-2db), but im telling you changing the monitors definately made a massive difference (note. having the genelec sub on/off makes no difference to the lower mid range improvement i talking of since the crossover is 85hz, i even started with 8040s from the shop and had the same improvement in the 200-500hz range, but with these for some reason i had worse sub response than the mackies because the low end trough moved (perhaps because the genelecs arent so deep, so further from front wall?), this is mainly why i switched to the 8030s plus sub to get back the 50-60hz sweet spot). both the fronts of the 624s and 8030s were in exactly the same positions whilst i was testing, and the improvement is massive all round the mix position. dont get me wrong the treatment is making a huge difference too. i have since done tests removing it all and reapplying with the genelecs as monitor, and the difference is nice and big still, i have 100+ response graphs for every piece i add and position tried. im in no doubt that adding more would improve things further and only take me closer to anechoic response, but its difficult because the walls are very soft so i can only put nails/pins into the sparsely laid beams.

im also thinking even if my room was reflection free id still have colouration from the furniture. i have a fairly standard desk in my room which seems to have a significant impact, despite the bottom of the speakers now being 8" from the top surface. i have tried changing the desk to one with 4 legs instead of the 2 slabs which are on most computer desks (whilst keeping the monitors and mic in same positions of course) and the difference was very noticable, although v small compared to the improvements from treatment and genelecs. i can also see the solid top surface has an affect by covering it with a thinner rockwool slab and witnessing another worthwhile improvement to the lower mid range (note. i dont suffer from the 160hz desktop boost some monitors have compenstion eq for). so i am considering building a desk with a perforated steel top.

another thing ive discovered is if i put the genelecs inside of the mackies then their response become very boomy too. this is far from accurate testing since the genes are now in a slightly different position, but has made me consider the posibility that putting speakers inside of one another in general is v bad for response (at least in small rooms).

anyway ive long had problems with an over active 200-500hz region in that room which ive always struggled to compensate for, it was amazing changing to the genelecs and hearing that region pop down a good 3-4db. i have remixed many tracks now to get the mids more accurate. but it seems a shame monitor shapes impact on room freq response may remain a secret to the public (not genelec), assuming my findings are valid. but i understand how unreliable a nobody internet source could be.

regards,
will.

[Ethan Winer]

Will,

> you seem to be denying the affect ive seen from changing the monitors? <

Not at all. But your graph compares Mackeis with no sub to Genelecs with a sub, so it's apples to oranges.

> having the genelec sub on/off makes no difference to the lower mid range improvement <

I believe you! It's probably an SBIR (boundary distance) type issue. If the speaker locations differ by even one inch a lot can change. Can you easily post a graph comparing both speakers with no sub on either?

> both the fronts of the 624s and 8030s were in exactly the same positions whilst i was testing, and the improvement is massive all round the mix position. <

Again, I believe you, but not being there in person makes it difficult for me to determine the reason.

> im also thinking even if my room was reflection free id still have colouration from the furniture. <

Getting rid of all early reflections will probably reduce the difference between speakers.

--Ethan

[wm]

hi ethan,

thanks for your response again, i appreciate the time taken.

im confused though, i dont get what the sub has to do with anything? ive compared 8040s with no sub against 624s with no sub, 8030s no sub against 264s no sub, and 8030s with sub against 624s no sub. all the same mid range improvement with the genes.

of course i appreciate moving mic and/or speaker a cm can change the response a lot! and thats why im not concerned with for exmaple the dip in the highs on that 624 waveform above, because up there the response changes instantly i move the mic, but the low mids dont change *much*, they stay boomy everywhere around the mix position. i tried for a long time refining the mackies positions for the best response. forward and/or down means more boomy 200-500hz, up meant less boom but worse sub response etc.

anyway in a few weeks i will be doing more testing with my 8030s in a friends studio (when its built) vs their 624s, to see what happens in a totally different small (12x12x7) studio. i'll report back.

all the best,
will.

[Ethan Winer]

Will,

> im confused though, i dont get what the sub has to do with anything? <

Even though your sub crosses over at a low frequency, it still has an effect at higher frequencies. For example, if the crossover is at 100 Hz and the slope is 6 dB per octave, then the sub is only 6 dB down at 200 Hz and only 12 dB down at 400 Hz. I have no idea if that's how yours is set up, but it's certainly possible for a sub to contribute up into the low mids.

> i appreciate moving mic and/or speaker a cm can change the response a lot! <

Here's another thought: How did you measure above 200 or 300 Hz - with sine waves? If so, you should try pink noise at 1/3 octaves instead, or find a program that can average the sine waves to 1/3 octave. At low frequencies you want high resolution to see the true extent of the nulls and to see the Q of the modal peaks. But at higher frequencies 1/3 octave averaging helps avoid the localized effects of comb filtering.

> up there the response changes instantly i move the mic, but the low mids dont change *much*, they stay boomy everywhere around the mix position. <

Okay, I agree, you're assessment is probably right.

--Ethan