SB Acoustics SB20FRPC30-8 (8" Fullrange Cheap Monster II)

[TNT]

Looking good! Thanks!

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[jzagaja]

What do you think?

 

[jzagaja]

Max absorption wavelength in Fano-type silencer is inversely proportional to ring thickness and propotional to helix angle, thus we need to run two coils for this two main peaks and higher harmonics.

 

[jzagaja]

Three times larger Vb.

 

[nandappe]

I tried measuring the on-axis response of the SB Acoustics SB20FRPC30-8 driver with a ping pong ball attached to the phase plug.
There is a slight change above 5kHz.

In terms of perceived sound, the presence of the ping pong ball results in smoother high frequencies.
It's intriguing how the addition of just one ping pong ball can alter the perceived sound.

 

[jzagaja]

Be careful because some plugs can have influence only in the near field.

 

[kp93300]

I tried measuring the on-axis response of the SB Acoustics SB20FRPC30-8 driver with a ping pong ball attached to the phase plug.
There is a slight change above 5kHz.

In terms of perceived sound, the presence of the ping pong ball results in smoother high frequencies.
It's intriguing how the addition of just one ping pong ball can alter the perceived sound.


View attachment 1185046

How do you fixed the ping pong ball ?

 

[nandappe]

How do you fixed the ping pong ball ?

The phase plug and the round shape of the ping pong ball fit together perfectly, so I simply attached it using a very thin double-sided tape.
It's so lightweight that it doesn't fall off either.

 

[duvixan]

Do you recommend the ping pong mod?
Are the sb20frpc30 your main listening speakers?

 

[nandappe]

Do you recommend the ping pong mod?
Are the sb20frpc30 your main listening speakers?

I think it's worth trying since ping pong balls cost around $1 for 6 piece.
Whether it's good or bad is up to individual judgment.

SB Acoustics SB20FRPC30-8 is a sub, while MAOP10 is the main speaker.

 

[BHD]

Try a ball of foam, like one of those stick on clown noses. It sounds silly but it might be interesting.

 

[kp93300]

The phase plug and the round shape of the ping pong ball fit together perfectly, so I simply attached it using a very thin double-sided tape.
It's so lightweight that it doesn't fall off either.

Hello
Is this mod reversible ?

 

[nandappe]

Is this mod reversible ?

Yes, we can attach and detach the driver without damaging it.

 

[zman01]

nandappe,

The ping pong ball mod reminds me of images I have come across on the Internet of Lowther drivers with large phase plugs.

 

[Freedom666]

I am sure the ball does do some dispersion. Must be audible.

I like the idea.

 

[Stanislav]

For fun re. strange phase plugs, check this out, at the end of the article, from Tony Gee:

 

[Andreani Gianluca]

Excuse me . does anyone know how to open the sabaj box a20a 2022?

 

[duvixan]

Modded Lowther from Rethm speakers (nsfw)

 

[Ivo]

For fun re. strange phase plugs, check this out, at the end of the article, from Tony Gee:

20-25 years ago, before I had a measurement mic and DSP, listening, non-destructive modding and listening again were my only tools. It was so much fun. ;-)

Back then, foam between a whizzer and main cone was my most effective tweak, but I remember it really only worked well when the driver had excess treble. Some treble was usually lost and it really hurt when the driver didn't have heaps to spare.

I also remember covering the baffle with a fairly thick layer of some damping material, like a folded fleece blanket or fiber material, would remove an edge from the sound. I guess I was working on baffle effects with that.

I once made tractrix horns for lowther drivers and while the square ones were good, I had made uneven petal horns that sounded soooo clean. I have yet to apply the same to regular sealed box etc designs, but avoiding standing waves and reflections in the midrange in any possible way must be a priority.

 

[Andreani Gianluca]

Parametri Thiel Small e raccomandazioni for this driver
https://www.petoindominique.fr/php/mysql_thiele_seul.php?hp=7852