Why does logitech have a capacitor- dual 2 inches

[scott68]

I opened a Logitech 530 satellite and I noticed a capacitor on the 2nd speaker. It is wired like this:
Green wire from amp to + on 1st spk and white wire from amp to neg on 2nd spk

On 2nd speaker, a capacitor across + and - on 2nd
Then a white wire from positive on 2nd speaker to neg on first speaker.
Thanks

 

[jrh0516]

Interesting filter that sums flat. Only impact is to reduce impedance at higher frequencies. I've not seen it before.

 

[phase_accurate]

BSC

 

[Don Hills]

The effect is to "short out" (bypass) the second speaker at high frequencies.
Actually, it's not for BSC. Note that the two drivers are in series at bass frequencies, this results in half the power so no net gain compared to a single driver with twice the power.
The main reasons are to (a) reduce the excursion for a given bass SPL and (b) to have only a single driver operating at high frequencies. If both drivers covered the full range there would be significant "lobing" effects where the sound level would vary depending on your head position.

 

[HumbleDeer]

I guess your questions are answered now. Logitech stuff isn't great, but the thought put into it is often neat to look back at.

The box on my Z906 might not have been great but for the size it wasn't bad at all. Never any chuffing.

 

[picowallspeaker]

Same for the Z523 that I rescued 3 months ago: never any chuffing !
Maybe it's due to the passive, a MDF disc

 

[HumbleDeer]

Same for the Z523 that I rescued 3 months ago: never any chuffing !
Maybe it's due to the passive, a MDF disc

Only vented enclosures can chuffing. Obviously, your passive radiator box won't chuffing because there's nothing the air sheers over.

 

[picowallspeaker]

BTW I recycled it by putting a car speaker - despite a bad group delay, it works good !
And the $5 bluetooth can with digital amplifier does the job ( ugly !)
The problem is how to get dispose of the 16 V/2A PSU and the 3 channel amp PCB, not to mention the ugly set of 1.5"'s

 

[phase_accurate]

Actually, it's not for BSC. Note that the two drivers are in series at bass frequencies, this results in half the power so no net gain compared to a single driver with twice the power.

You are right. I think I shouldn't post before being awake. If it were current driven (what I don't expect it to be) then it would actually be possible to do BSC like that.

I guess it is most probably there to reduce lobing higher up.

regards

Charles

 

[scott68]

Thanks guys, now that I know about lobing, it brings up another question. I'm building a small portable, hopefully with a better sound then most, system. The Left, center and right speakers ( 3") will have a 2 inch space between them with the woofer and passive radiator out the back. Is that going to be a problem?
thanks

 

[TBTL]

If left / center / right are on the same side (same panel), then you get the lobing issue again. That is no big problem in a portable loudspeaker however.

 

[HumbleDeer]

You're not going to be in a fixed and calculated listening position with those. With stationary more permanent setups you'd want to avoid it.

Sent from my Archos Diamond S using Tapatalk

 

[scott68]

Thanks, for those comments. As a reference, using a permanent seat, how far does the left and right need to be spaced apart? I assume that depends on how away the permanent seat is. Is there a formula for that? And if you add a center speaker, how does that affect the lobing?

 

[picowallspeaker]

There are two ways ( for making a stereophonic recording )
Place two microphones ( on axys ... ) in front of the musical venue
According to their POLAR response they will caption the sound(s) arriving
so there's an internal "timing" in this system that it's been created, where time & distance move together, and during reproduction it will be released.
The real difference between a live sound and a reproduced one is that with the latter you lose the sense of distance related to sound intensity ( as you can walk and approach to the source, louder ).

The other way of making a media with stereo tracks, well, use more than 2 mics, or ....

 

[scott68]

I'm not sure I follow what you are trying to tell me?

 

[picowallspeaker]

With dual tracks ( stereo)
you obtain a stereo image by making the summation at your ears of what arrives from the L and R channel.
Check how phase ( which contains the timing information ) combines from both sources, as it has been mastered. It's the same information that the mics captioned. Different if the master is obtained from mixing & added reverb etc.

The lobe ( I think ) is a characteristic of the polar diagram.