Adam A7 : bass reflex question

Scube · Post by **Scube** » Sat Jan 17, 2009 1:46 pm

Hi There, I know that currently Live 8 topics rule but I try all the same.

I've purchased a couple of Adam A7, actually great loudspeakers. I pass over their quality and I ask you: do you think there are problems if I plug the bass reflex holes? Can this procedure damage the loudspeakers?

This question is because I've a problem with low-reflections and this method make the sound super dry and compact. A friend of mine have a couple of Dynaudio and he plugged the reflex holes on his vendor's advice. I just want to be sure that I will not destroy my new toys. Suggestions?

Scube

P.S. Oh..usually I like to work with a not-excessive volume

Superchibisan · Post by **Superchibisan** » Sat Jan 17, 2009 5:59 pm

it will not damage your speakers at low volumes. but at extreme high volume, it might have a detrimental effects.

after having blue sky exos, i don't understand ported design. people just use it for extended low freq response, but to me, it sounds terrible. why not just make your speaker extend that low!

Tone Deft · Post by **Tone Deft** » Sat Jan 17, 2009 6:08 pm

listen to them for a while before you go messing with them. you don't yet really know how they sound. sounds like a dumb idea anyway, if you want to adjust the sound, use the adjustments on the back. reflections are a problem with the room, not the speaker. you're not actually fixing anything with your suggestions, you're just covering the problem up.

8O · Post by 8O » Sat Jan 17, 2009 6:15 pm

Also, depends what you plug them with. My Dynaudio hifi speakers came with purpose-designed foam plugs that can be used if required. I'd use a similar material and not something completely opaque like huge gobs of blu-tac (you'd be surprised what some people do...).

Edit: What Tone Deft said. I've never needed the foam plugs for my own Dynaudios.

heavensdaw · Post by **heavensdaw** » Sat Jan 17, 2009 6:47 pm

Tone Deft wrote:listen to them for a while before you go messing with them. you don't yet really know how they sound. sounds like a dumb idea anyway, if you want to adjust the sound, use the adjustments on the back. reflections are a problem with the room, not the speaker. you're not actually fixing anything with your suggestions, you're just covering the problem up.

+1

Hd

Tone Deft · Post by **Tone Deft** » Sat Jan 17, 2009 7:38 pm

re-thinking this, I know your problem, I had the same situation, it's not room reflections (noted by "usually I like to work with a not-excessive volume.")

I brought my Adams home late one night, plugged them in and put on some mp3s, they sounded awful, resonance around 100Hz, I blamed the mp3s and went to bed. next day, same thing, wtf? I contacted Adam, they recommended Auralex oam pads to put under the monitors. instant fix!!

problem is, I put them on the shelf on top of my desk, a very poor place to put them, sitting on top of a not well supported piece of wood, this caused the resonance.

you want monitors to either be completely floating in the air or sitting on something ROCK solid, anything in between leads to unwanted resonance. sound is just air pressure waves hitting our ears. those pressure waves are the speaker cone pushing on the air. in turn the speaker cone pushes against the cabinet, the cabinet pushes against whatever its sitting on. if it's sitting on an unstable surface, that will affect how effectively the cone can push against the air. an analogy would be pushing a kid on a swing while you're standing on a skateboard as opposed to standing firmly on the ground.

floating or sitting on solid rock, you get a flatter frequency response (no resonant peaks.) if you float them, you can lose some bass response, so turn up the bass with the controls on the back per your liking (I left mine alone.) likewise sitting on solid rock you might get too much bass, so you might want to turn the down.

hth tell your friend the same thing, he's crapping on his speakers plugging the bass port, AFAIK they're not designed to be optionally plugged, it seems so unscientific and inexact. if you plug them, how much do you plug them? with what? too much slop in that fix for it to seem reasonable.

8O · Post by 8O » Sat Jan 17, 2009 7:52 pm

Tone Deft wrote:hth tell your friend the same thing, he's crapping on his speakers plugging the bass port, AFAIK they're not designed to be optionally plugged, it seems so unscientific and inexact. if you plug them, how much do you plug them? with what? too much slop in that fix for it to seem reasonable.

From my Dynaudio manual, after many suggestions about positioning and stands:

To minimize low frequency reflections, which will be heard as a thickening of the sound, the Focus models can be adapted to the room's acoustic character by using foam plugs in the bass reflex port. This will essentially attenuate the room-induced boost in the low frequency range by dampening the deep frequencies, yielding a more clear and tight sound and minimized reflections when the loudspeaker is positioned near rear walls.
Fully insert the foam port plugs packed with your loudspeaker into the bass reflex tube, to attenuate the bass output (if required).

Note: that quote is for hifi speakers typically used in the living room, not monitors.

Tone Deft · Post by **Tone Deft** » Sat Jan 17, 2009 7:57 pm

thanks for that. I googled a bit, people do use this technique, I just find it odd. maybe it is perfectly fine, sometimes the obvious simple solutions are the most elegant. try both techniques, use your ears, keep it simple and don't muck with them too much, they're well designed, gotta respect the engineering that went into them.

edit - IMO it seems that you have a resonance problem. foam in the port limits the frequency of your monitors but won't fix the resonance. foam under the monitors will fix the resonance and you won't lose frequency content.

my $0.02, I'd be curious to hear how this works for you.

muthafunka · Post by **muthafunka** » Sun Jan 18, 2009 2:28 am

I'd go looking at positioning, stands and maybe building some bass traps for your room. You can buy/use 3 small isolator feet under each speaker too, this should help. If what you're hearing is resonance and you block the holes to correct it, you're basically replacing your speakers with your walls to produce those frequencies and will possibly lose a lot of subtle frequencies as your walls probably have a poorer response than the A7s

The A7s have years of engineering in their design and the port is there for a reason. True the Dynaudio manual said you can block the ports but the Adam one doesn't. I reckon working on your room/set-up will give you much better long-term improvements. You spent all that cash on the Adams and they're beautiful monitors, why hobble them with a botch job?