Need basic Information about Subwoofer and Coax Audio Cables

[therock003]

Just a couple of beginner questions for my audio setup.

-Why does the cable that came with my subwoofer has 2 kacks on each end. One looks like a purple RCA cable which you connect to the woofer, and the Receiver respectively, and then it has got a second jack on each ends which is a plain 3.5mm jack that does not connect to anything. Whats its purpose?

-I need to connect an audio device to my AV-Receiver through coaxial interface, but i dont have a coaxial cable at the moment. Is it ok if i hook a plain Red/White RCA cable until i get a coaxial cable (Of course whichever colour is connected in one end, the same will be on the other.

[jagabo]

Some devices (like a computer audio cards) use 3.5mm jacks rather than RCA connectors.

[therock003]

Some devices (like a computer audio cards) use 3.5mm jacks rather than RCA connectors.

You mean as output for the woofer?

Ok and as for the coaxial cable can you confirm please if i can use an rca jack indeed. I googled and they say thats no problem i just want to make sure.

So an coaxial is just a heavy duty rca with wider shielding and gold braided ends?

[CBC]

https://www.informit.com/articles/article.aspx?p=349880&seqNum=2

[johnmeyer]

It would help to know the make and model of the subwoofer. Have you looked at the instruction or setup manual? These are usually easily available online.

I agree with the other people that the 3.5mm jack could simply be an alternative connection. It could also be some sort of control line. I have not seen this with subwoofers, but it is quite common on A/V equipment to have a 3.5mm jack used for either infrared input (IR via and electrical rather than optical input) or simple control, like on/off.

[Cornucopia]

"Pix or it didn't happen".
IOW, we need much more info from you. Pictures would be good, but detailed model# info is just as helpful.

I agree, likely the cable with the dual connectors is probably just designed to cover varying devices and their varying connection types.

"Coax" is a confusing term, because while most people might (rightly) assume it connotes an F-type RF connector with with a solid single wire conductor core surrounded by rather thick insulation, then a braided shield/ground, then the outer covering. But the term can also apply to RCA-type phono connections, as they are similarly constructed (though usually w twisted/braided innermost conductor, and much less insulation).

Which one are you referring to?

Note: many/most subwoofers are active subs, so their connection is often not post-power amp, but are line-level from the pre-amp. And that is why they often make use of RCA connections, since those are ubiquitous on pre-amps & receivers.

Scott

[johnmeyer]

"Coax" is a confusing term, because while most people might (rightly) assume it connotes an F-type RF connector with with a solid single wire conductor core surrounded by rather thick insulation, then a braided shield/ground, then the outer covering. But the term can also apply to RCA-type phono connections, as they are similarly constructed (though usually w twisted/braided innermost conductor, and much less insulation).

Which one are you referring to?

Scott,

I had the same question, and it threw me for a moment because, as it turns out, some subwoofers DO have a coax connection.

Mine does.

The early 1990s Velodyne subwoofers had a feedback servo that modified the cone excursion in real time in order "articulate" the bass more precisely. Even though everything in a subwoofer happens at extremely low (below 120 Hz) frequencies, the control signal was actually a very high frequency, feeding back what I assume was first or second derivative (i.e., rate of change) information to the controller which was a separate unit, designed to be mounted in an equipment rack in a closet. So the connection was two wires, via banana plugs, to provide the low frequency signal, and some RG59 or RG6 coax for the feedback signal.

-----------

Velodyne ULD-15 and other high-end subwoofers
https://www.stereophile.com/subwoofers/velodyne_uld-18_amp_uld-15_subwoofers/index.html

[Cornucopia]

@johnmeyer, that's one reason I wasn't discounting the description as a matter of course. I knew there were some that did. But those are rare. I assume that feedback unit dynamically adjust the damping. Not sure whether that ultimately is a bonus or not. Hope it sounds good.
Reading that article reminds me of being in church sitting next to an organ that has true 32' pipes!! Talk about low notes, you DO feel it.

Scott

[therock003]

I solved my problem since my Receiver offers direct connection to the iphone, but for future reference i would still like to know whats going on. So i f you would care to entertain this discussion, the whole thing goes like this.

I initially wanted to connect my mobile to a usb DAC (C5DAC) and then using coaxial to go to my AVR (Harman Kardon 151s). So that i had a direct digital connection until i reached the receiver and not use the phones 3.5mm jack headphone as an output to the RCA on my AVR and chop everything down.

The in/outs are those

http://audio-ph.ru/media/storage/image/20160907/1473235200873399.jpg
http://audio-ph.ru/media/storage/image/20160907/1473235296954170.jpg



Reminder, its just a theoretical conversation at this point since i can connect iphone via usb directly so theres no moe point for any of that. Its just a matter of if i ever want to carry out a signal this way so it reaches something digitally through the coaxial output

EDIT: Oh and BTW heres the image of that cable i was talking about. Each end has both the woofer jack in RCA format and 3.5


[Attachment 52790 - Click to enlarge]

[Cornucopia]

That special sub cable could be 2 independent parallel runs (rca<-->rca, 3.5mm<-->3.5mm) that you choose from, or they could be Y'd at one or both ends. If they are Y'd, you'd best not use that cable and instead just use a single, normal straight rca<--rca to avoid the possibility of introducing hum.

The "coax" that you have been referring to is the coaxial form of SPDIF (the other being the optical form, aka "toslink"). You can basically use a standard rca<-->rca (though there is some minor impedance differences between std analog rca/phono and spdif coax, but it won't matter with digital). Spdif is a digital connection. And that particular one on your amp is a digital input only, no output. That's standard for most amps.
I looked up your C5DAC and it appears to have it's own proprietary physical form of "coax out" that would guess based on the picture that it is using a TRS 3.5mm connector. But don't take that as gospel - I strongly recommend you get with the manufacturer and get an adapter cable so that it can go into the rca-type "coax" spdif input on your amp. I notice on their website they show it going into one of their branded amp/dac devices, so maybe they don't have an adapter but expect you to buy this additional device (which from the pic is primarily going back to analog). You COULD buy or craft your own 3.5mm<-->rca adapter cable, but without knowing the pinouts you could possibly damage a component, so best to get something manufacturer approved (unless you have the full schematics and it's obvious).

Scott

[johnmeyer]

The "coax" that you have been referring to is the coaxial form of SPDIF (the other being the optical form, aka "toslink").

Oh wow, how did I miss that?? I feel like an idiot. Thanks for figuring that out.