Does a build in speaker project sound similar to a cardioid speaker ?

[Marc v E]

I just had a brainwave that lead me to this question.

My understanding is that a cardioid speaker projects the bass forward in order to minimize reflections of the back wall.

A build in speaker has an almost infinite baffle which, I presume, causes the bass sounds to reflect almost immediately after the speaker cone, which should result in me not noticing a difference between the direct and reflected sound. Is this correct ?

And if there are benificial effects of building a speaker into a wall, can the same be said of placing speakers in a wide bookcase ?

 

[Heinrich]

And if there are benificial effects of building a speaker into a wall, can the same be said of placing speakers in a wide bookcase ?

I'm likewise interested. I recently built a speaker (DIY) that is intended to be used inside a filled bookshelf. Dr. Toole wants the direct sound to be flat, not tilted. The Harman tilt originates to a bigger part in soundewaves that go around the speaker box, and these are quite bassy. The latter is missing with real bookshelf mount.

What consequences are expected, what should I focus my attention on? Can I measure it?

The usual suspects in regard to cardioid show good adherence to the tilt, though.

 

[kimmosto]

In DIY scene some may start to balance half space and cardioid speakers with VituixCAD's initial slope targets for half space designs. For example this is one of my favorite small half space designs:

Slope target ranges are opaque green (ON+LW), orange (PIR) and blue (SP). Slope ranges are based on logic and experience that PIR slope should be close to same as with conventional full space design. Assuming that tweeter does not have wave guide or wave guide is very shallow, on-axis and listening window should be tilted slightly down compared to full space design. Sound power is much less tilted down compared to full space design because there's no pressure at rear sector which is attenuated at HF with conventional box concept. Minimum DI is 3 dB without rear radiation so directivity is quite naturally very smooth with conventional drivers are layouts.
This concept is really brilliant for any kind of listening, but common problem with zero-diffraction designs is that they require quite much free and smooth wall area. For example 70 cm around speakers without any steps.

 

[Heinrich]

Slope target ranges are opaque green (ON+LW), orange (PIR) and blue (SP). Slope ranges are based on logic and experience that PIR slope should be close to same as with conventional full space design. Assuming that tweeter does not have wave guide or wave guide is very shallow, on-axis and listening window should be tilted slightly down compared to full space design. Sound power is much less tilted down compared to full space design ...

Basically the bass/mids are a bit elevated in the direct field , 4dB in this case, as to compensate for the latter, the leaner diffuse field. Anyway, I'm looking forward for a reasonable discussion of this topic. My not that recent attempt to start this got a bit scrambled.

One additional aspect maybe. Since the spekers are tied to the wall, they cannot be toe'd in.

 

[kimmosto]

One additional aspect maybe. Since the spekers are tied to the wall, they cannot be toe'd in.

Wall concept does not need toe in or out assuming that distance between the speakers is not too long and tweeter is conventional (dome) without or with shallow wave guide such as Seas DXT. Zero-diffraction concepts support very wide range of listening distances close to 0 i.e. forehead between the speakers. Soundstage is large - kinda room-filling. I know a case where 1238 was replaced with this individual:

Active preset could/should have slightly more bass if room acoustics is harsh.
Note. These samples show some diffraction due to recessed baffle, frame for fabric cover and finite measurement baffle. More ideal application does not have those.