Banana Plugs to subwoofer (RCA) conversion

Banana Plugs to subwoofer (RCA) conversion

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Discussion

Autopilot

Original Poster:

1,155 posts

142 months

Friday 6th December 2019
quotequote all
Hello All,

I'm doing a house renovation and building all the cabling in to walls to keep things nice and tidy. The AV Receiver is located under the stairs and terminates in to an audio patch panel in a small server rack. The speaker cabling then runs through the walls and ends up as small plates with banana plugs where the speakers will go.

As a subwoofer uses a single cable with single connector at each end, I kind of expected the plates where the subs will plug in to have a single RCA connector on the wall so that I can use a sub lead from the wall plate to the subs. Instead, I have banana plugs which has speaker cable running through the walls back to the patch panel.

He informs me...and I have no reason not to believe him, that I can essentially make a cable that has 2 banana plugs on one end and a single sub connector on the other end (I'm not using LFE).

Having a look on the internet, I have found one or two examples of these types of cable, but it's been few and far between.

My first question is:

Can I use speaker cable with the necessary converters at either end to run a sub? I will obviously need a single sub connector from the amp to a pair on banana plugs on the patch panel and then at the other end, a pair of banana plugs going in to a sub connector.

My second question is:

Has anybody done this or bought cables of this type? I'm happy making them, so if in principal this all works, I dare say I'll make something up rather than buy anything so I can bespoke it to my needs.

Many thanks

Autopilot



SS2.

12,425 posts

196 months

Friday 6th December 2019
quotequote all
Don't see any problem doing that, although I might opt for a screened two-core cable.

I'd probably buy a pre-made sub cable (with phono plugs at both ends), cut one end off and fit banana plugs to the +ve & -ve cores.

red997

1,282 posts

167 months

Friday 6th December 2019
quotequote all
should be fine;
RCA outputs from processors are relatively low impedance (i.e. 300 ohms) to drive coax cables (relatively high capacitance).
Driving speaker cables is easy for the processor;
Input of your active sub will be relatively high impedance (i.e. 10K ohms), so a nice and easy drive.

At worst case, depending on the length and placement of your speaker cable, you may have some noise pickup from surrounding equipment on the unshielded speaker wire.
I would however be very surprised if you do, and it will almost certainly be inaudible

Autopilot

Original Poster:

1,155 posts

142 months

Friday 6th December 2019
quotequote all
Thanks guys, that’s exactly what I was hoping to hear. I do happen to have two brand new unused sub cables asking to be chopped up so will most definitely use those and add banana plugs to the other end. Both runs should be quite short as the sub will be positioned right by the socket on the wall so will only be 50cm or so and the amp end is about 1.5 metres from the audio patch so will be fairly short that end.

Thank you!!

TonyRPH

10,462 posts

126 months

Friday 6th December 2019
quotequote all
If the cable running through the walls isn't shielded, you will end up with a lot of hum.

Your proposed idea as I understand it:

AV Receiver ----> screened 'phono' cable ---> banana plugs ---|| wall || banana plugs ---> screened cable ---> sub.

Is this ^^^ correct?


Autopilot

Original Poster:

1,155 posts

142 months

Friday 6th December 2019
quotequote all
Yes, that’s exactly the setup. One thing that has been considered is that the speaker cables are in completely separate runs and away from power cables for that very reason

TonyRPH

10,462 posts

126 months

Friday 6th December 2019
quotequote all
I'm 100% sure that will hum.

Good luck.

Mr Pointy

6,350 posts

117 months

Friday 6th December 2019
quotequote all
TonyRPH said:
I'm 100% sure that will hum.
Why will it hum?

gizlaroc

15,367 posts

182 months

Saturday 7th December 2019
quotequote all
TonyRPH said:
I'm 100% sure that will hum.

Good luck.
I agree.


Autopilot

Original Poster:

1,155 posts

142 months

Saturday 7th December 2019
quotequote all
I prefer Red997’s response to be honest 😀

I’m fairly close to testing it all, I’m doing the Server rack end of business at the moment, so will update. If it fails miserably, I will of course lie, say it’s the best thing ever and quietly rip cables out and redo it quickly 😀

I’ll report back in soon!

Thanks for your responses

TonyRPH

10,462 posts

126 months

Saturday 7th December 2019
quotequote all
Mr Pointy said:
TonyRPH said:
I'm 100% sure that will hum.
Why will it hum?
Because the unshielded speaker wire running through the wall doesn't offer any protection against mains hum pickup.

I had a poor quality screened cable 4M long that induced hum in my sub, despite me routing it away from mains cables and other potential sources of hum.

You need to bear in mind that the purpose of a sub is to amplify very low frequencies, and as such it is unusually sensitive to hum when using the RCA inputs.

This is unlikely to be a problem when using the high level inputs (if it has any).

megaphone

8,863 posts

209 months

Saturday 7th December 2019
quotequote all
I agree it may hum, I'd be setting it up and testing it before going too far, cable really should be screened signal cable.

I have done a similar job where the electrician ran in mains flex instead of a screen cable, it worked for me however it was a 'balanced' signal, hot, cold and ground, so was able to get away with the mains flex.

Alternative option is to use passive subs and put an amp at the headend.

tdm34

6,619 posts

168 months

Saturday 7th December 2019
quotequote all
I'd just change the wall plates for the correct ones, if there's only a short distance between the plates as you said it should be easy to draw a correct shielded rca cable through using the speaker cable your contractor used, won't cost fortunes, because if you don't you will get hum by using non shielded cabling, back in the day I used to do a lot of AV installs and one of my customers had pre wired everything including using normal speaker cable for his sub which ran ran across the room under a laminate wooden floor, i'd told him specifically not to do it that way but he did and his sub hummed like crazy, luckily he only had to remove the skirting board for me to fit a much longer shielded rca cable around the room.

TonyRPH

10,462 posts

126 months

Sunday 8th December 2019
quotequote all
Autopilot said:
<snip>

I’ll report back in soon!

Thanks for your responses
So how did it go OP?

Did you get some hum?

gizlaroc

15,367 posts

182 months

Sunday 8th December 2019
quotequote all
Autopilot said:
I prefer Red997’s response to be honest
Of course you do, that is the answer you wanted to hear.



You will be sending 1.5v over a long run cable with no shielding.

My Rel sub hums now with shielded cabling, and it is only 3m.


TonyRPH

10,462 posts

126 months

Tuesday 10th December 2019
quotequote all
Am I the only one who gets annoyed when an OP doesn't provide us with thread closure?

Oh well...

Red 5

677 posts

138 months

Tuesday 10th December 2019
quotequote all
TonyRPH said:
Am I the only one who gets annoyed when an OP doesn't provide us with thread closure?

Oh well...
You’re not alone, but it’s getting more of a rare occurrence, that any thread you contribute to will be concluded by the OP
Nobody likes to offer advise / opinion only to be ignored after all.

It’s a sad fact, that DIY AV projects often end up like this frown

The blind leading the blind (or electricians), then looking for impossible / implausible fixes for easy to avoid schoolboy errors, that end up good costing money to fix.

Running speaker cable to a sub is one of the most popular mistakes!

Unscreened cables essentially act like an antenna, which when connected to a big amp and LF unit, will be heard as a hum.







Autopilot

Original Poster:

1,155 posts

142 months

Monday 16th December 2019
quotequote all
TonyRPH said:
Am I the only one who gets annoyed when an OP doesn't provide us with thread closure?

Oh well...
I'd not forgotten! My partner has selfishly been in hospital so has completely wrecked my plans to finish my install. Women eh!!

I will most definitely give an update but won't get a chance to do anything until the weekend as I'm up to my neck in work this week. The electrician working on my house is going to be there on Thursday and Friday so was hoping to have this all done by now so that I could get him to feed some new shielded cable and swap the banana plug sockets over to RCA if required. I'm quite tempted to get him to do it anyway without testing but don't feel that will give the right closure for this thread smile

I'll update soon!!

Some Gump

11,409 posts

144 months

megaphone

8,863 posts

209 months

Tuesday 17th December 2019
quotequote all
Get the electrician to put in a screened cable but leave in the speaker cable as well, then you can test and play and it's always there if you need it for something else.