Suggestions on how to calm bass down on Wharfedal Pacific PI 40's

[mixter_v]

I have the pacific PI 40 speakers hooked up to my Sony STR DA 1200ES AV amp. When listening to audio, the soundstage is good, apart from frequencies below around 150 Hz, where the bass has lost its definition. The speakers are floor standing on a wood floor, so cannot use spikes directly.

I move them about 30 cm from the back wall to reduce the accoustic effects of rear radiation.

Any suggestions on how to calm bass down without resorting to using equalisation adjustments.

[Cal Weldon]

Stick a sock in it.

Try running your ports aperiodic. Adjust to suit.

Try also placing the speakers on a piece of carpet or padding to help decouple it from the floor.

[mixter_v]

Hi, Carl,

Not sure what you mean by running my ports 'aperiodic'. Can you please expand.

[David Gatti]

Remove the bass driver and add more stuffing - dacron, polyester or wool. That will dampen the bass response and clean up the mids a bit.

[David Gatti]

Aperiodic - basically a stuffed port creating a slow release of air pressure.

[PeteMcK]

lift them up from the floor, (in Aus we can use milk crates - not very aesthetic but most useful device known to workshop man...)
that will diminish the effect of room gain somewhat & hence clean up the low end...

[gedlee]

Use multiple subs.

[BlueWizard]

First, let's establish that this speaker is rear ported. I couldn't find any pictures of it, but the newer Pacific Evolution 40 appears to be front ported.

If it is rear ported, the 12" (30cm) from the back wall is not enough. I would guess it need to be minimum 0.5 Meters to 1.0 Meters, and likely at least 1.0 Meters from the side wall.

Though, if it is front ported, that may be adequate.

Also, I think 'stuffing' the port only applies to rear ported cabinets.

Although, it depends on why you are stuffing them.

You make two seeming contradictory statements -

- You want to calm the bass
- Bass has lost definition

The first implies too much bass, the second implies not enough.

Also, you say it lost definition; does that imply it once had bass definition, and if so, how are the present circumstances different from those previous more favorable circumstances?

Are you sure your AV amp is set up properly?

Are you using the system with a Sub?
Is the Sub set up properly?
Just to be sure, how is the Sub setup? Crossover? Phase angle? Slopes?

You are not using spikes with the speakers. Can we assume that the bottom of the speaker cabinets is just sitting on the hardwood floors?

Any chance the wood floors are floating. I've recently read of several people having problems with floating wood floors. Several tried solid stone/concrete type masses under the speaker with no improvement. What finally worked was an MDF box filled with sand acting as a low stand for the speaker. The Sand Box also sat on some polypods to help isolate it from the floor.

I think before we can make an accurate guess about your situation, we need a few more details.

Steve/bluewizard

[mixter_v]

Hi,
Thanks for the replies so far. To clarify further:

I am not using a sub
The PI40's are the old version of the evolutions - main difference is cabinet construction, so they are front ported.
There is plenty of bass, but from about 150Hz it loses definition. What I mean by this is, for example, a kick drum is deep, but not tight, same for bass guitar.
The floor is a floating floor
The speakers are about 1.1m high, so I do not want to raise them too much otherwise the top fitted tweeters will be firing over my head.
AV amp set up fine, when on CD source, I am using analogue direct signal feed, so no EQ settings are being made.

[BlueWizard]

This came up in a discussion recently in a UK AV forum about speakers spikes.

Floor standers & Spikes
http://www.avforums.com/forums/showthread.php?t=812799

Which in turn lead to a discussion of Isolation vs Coupling. Under some circumstances the purpose of Speaker Spike is to couple the speakers as tightly to the floor as possible.

Others have put polypod or Deflex under speakers or other various HiFi equipment to isolate it while still having it sit solid on a surface.

This eventually turned to putting various forms of mass under the speakers. Some people have found putting slabs of marble or granite under the speakers helps couple and isolate them. Granite kitchen cutting boards work well and are relatively cheap.

But on floating wood floors, one person found that granite slabs didn't work at all. So, he created a 6" MDF box filled with sand, that we referred to as 'soft mass' to distinguish if from the 'hard mass' of granite, concrete, and other stone.

It seems that this 'soft mass' does work exceptionally well on Floating Wood floors.

His boxes are 6" thick, but that served his speakers well, and when you see the picture of his speakers (in the thread linked to above) you will see why.

In your case, I could picture something with a larger base, maybe 1.5" to 2" deep, braced, and filled with sand.

Also, note that the 'sand box' person in the above discussion place polypod under the base to isolate if from the floor. The PolyPods are a very special acoustic rubber, that seems hard under normal circumstances, but at low frequency if become vaguely liquid and converts vibration into heat. They can be used to isolate all kinds of music equipment; turntables, CD players, etc....

I don't have a solution to your problem, but maybe there is something in what I've said that will help. Prior to this AVForums conversation, I have never considered that Floating Floors might be a problem.

Steve/bluewizard