Bluetooth amplifier for rear speakers running from leisure battery

[CJW]

Hi. Quite chuffed with this and wanted to share. I installed some rear speakers (Focal RCX-100 4” Coaxial) with a view to adding them to my head unit. After monitoring my starter battery, and seeing it sit at about 12.3-12.4V, I then wished I could run sound off the leisure battery to avoid ever flattening the starter whilst in camp. Rather than try and power the head unit off the LB, I found this unit on eBay and thought it worth a punt.



The specs seemed right - Bluetooth 5.0 and a class D amplifier, but £25? It’s gotta be sh*t, right? Well, no… it’s actually really good, especially for voice and pretty handy for music too. I’m not talking about blasting a campsite, I’m wanting to listen to something while prepping food for the family etc.

It fits in the cubby hole (finally, found a use!) and draws only 0.15A. Will accept dc voltage from 9-24V.



It’s got a rubbish name - Miniampl and is made by the equally badly named Nobsound. The cables etc it comes with are trash but the unit itself is OK.

It sounds great, and I’m picky. I can’t get over how little power it draws when playing.



Next stage is to add a speaker switch in the cubby hole so I can choose whether the Focals stand alone like this or as rears as part of the main van sound system.

 

[jimc91]

Nobsound - where’s Jog?

 

[Ivor]

Hi. Quite chuffed with this and wanted to share. I installed some rear speakers (Focal RCX-100 4” Coaxial) with a view to adding them to my head unit. After monitoring my starter battery, and seeing it sit at about 12.3-12.4V, I then wished I could run sound off the leisure battery to avoid ever flattening the starter whilst in camp. Rather than try and power the head unit off the LB, I found this unit on eBay and thought it worth a punt.

View attachment 151477

The specs seemed right - Bluetooth 5.0 and a class D amplifier, but £25? It’s gotta be sh*t, right? Well, no… it’s actually really good, especially for voice and pretty handy for music too. I’m not talking about blasting a campsite, I’m wanting to listen to something while prepping food for the family etc.

It fits in the cubby hole (finally, found a use!) and draws only 0.15A. Will accept dc voltage from 9-24V.

View attachment 151475

It’s got a rubbish name - Miniampl and is made by the equally badly named Nobsound. The cables etc it comes with are trash but the unit itself is OK.

It sounds great, and I’m picky. I can’t get over how little power it draws when playing.

View attachment 151476

Next stage is to add a speaker switch in the cubby hole so I can choose whether the Focals stand alone like this or as rears as part of the main van sound system.

Hi CJW, really curious about this set up you have, is the miniamp powered off the main or leisure battery? Currently? Really like the idea of being able to switch the speakers to the head unit or the amp. Assuming you just Bluetooth stream from your phone to the amp?

 

[CJW]

Hi @Ivor. The miniamp is powered off the leisure battery and draws just 0.15A. I didn’t want the risk of draining the starter by accident.

I changed my head unit a few months back which meant that my rear speakers are now attached to both the head unit and the MiniAmp in parallel. The end result being that the rears work from the head unit when I’m using that, and just the rears work from the MiniAmp. I never operate both systems at the same time.

Yes, it’s just seen as a BT device on my phone and works well - connects every time.

If you decide to do it, I can sketch you a simple circuit diagram.

Chris

 

[Ivor]

Hi @Ivor. The miniamp is powered off the leisure battery and draws just 0.15A. I didn’t want the risk of draining the starter by accident.

I changed my head unit a few months back which meant that my rear speakers are now attached to both the head unit and the MiniAmp in parallel. The end result being that the rears work from the head unit when I’m using that, and just the rears work from the MiniAmp. I never operate both systems at the same time.

Yes, it’s just seen as a BT device on my phone and works well - connects every time.

If you decide to do it, I can sketch you a simple circuit diagram.

Chris

Hi CJW, that sounds like a great set up! Thanks for replying. So you’ve just connected both units to the speakers via a bus bar a similar? No switch needed ?
We’ve got a little 12v tv which has terrible onboard sound, so like the idea of plugging it into the miniamp via aux.

 

[CJW]

No switch needed *in my case*. I read somewhere that (if you have a standard head unit) if your van starts up and the rear speakers aren’t detected, it could knock the fader function out, so it would be imperative to have the switch in the right position before EVERY ignition cycle (yikes). As it happened, I upgraded to a third party head unit which doesn’t try to be clever like that so no switch is now needed.

I just twisted the head unit speaker output wire and the wire that goes to the speaker itself together, and connected them to the MiniAmp using the hefty screw terminals on the back. Photo attached - pulled the unit out to show you.

Aux would work - there’s a stereo 3.5mm mini jack on the front. You could run a cable to a convenient point near the telly.

 

[Ivor]

No switch needed *in my case*. I read somewhere that (if you have a standard head unit) if your van starts up and the rear speakers aren’t detected, it could knock the fader function out, so it would be imperative to have the switch in the right position before EVERY ignition cycle (yikes). As it happened, I upgraded to a third party head unit which doesn’t try to be clever like that so no switch is now needed.

I just twisted the head unit speaker output wire and the wire that goes to the speaker itself together, and connected them to the MiniAmp using the hefty screw terminals on the back. Photo attached - pulled the unit out to show you.

Aux would work - there’s a stereo 3.5mm mini jack on the front. You could run a cable to a convenient point near the telly.

View attachment 209424

That makes sense, so technically the speakers are always connected to the head unit. Mines a std unit so this would matter.
Assume then you’ve taken the headline out in the cab to run the cables down the pillar and up the back of the dash? How much of a job did you find it?
Also, how good is the Bluetooth connection with your phone/device? Solid?

 

[CJW]

That makes sense, so technically the speakers are always connected to the head unit. Mines a std unit so this would matter.
Assume then you’ve taken the headline out in the cab to run the cables down the pillar and up the back of the dash? How much of a job did you find it?
Also, how good is the Bluetooth connection with your phone/device? Solid?

The headlining doesn’t need to come totally out - with a decent cable puller it was possible to do it by removing the handles above the door, the Sun visors and the headliner junction strip at high level where the bulkhead would go.

BT is BT5.0 - very solid a great range. Never let me down.

I don’t know if you’ll need a switch. Perhaps it will be fine just connected as mine is, but making sure that the MiniAmp is always off when you start the ignition. The power supply to mine has an isolator, but pressing the big dial on the from does switch the unit off too.

 

[Ivor]

Now the challenge is where do I put the speakers. Is your van a camper? Did you go with speaker pods or have you mounted them elsewhere?

 

[CJW]

I put mine near the C pillar. Because our u-shaped seat / bench means people sit very close to the tailgate, couldn’t really use the corner mounts. Works well.

 

[Ivor]

I put mine near the C pillar. Because our u-shaped seat / bench means people sit very close to the tailgate, couldn’t really use the corner mounts. Works well.

View attachment 209512

hI @CJW , finally getting around to this, going to take my time with it. Just picked up some speakers so going to run all the cables for them and the little amp (going to put it in the same spot you have). Can I ask about the power to the amp? did you just use the power supply that came with it or, because it will take 9V, you've just wired it directly to the battery?

 

[CJW]

hI @CJW , finally getting around to this, going to take my time with it. Just picked up some speakers so going to run all the cables for them and the little amp (going to put it in the same spot you have). Can I ask about the power to the amp? did you just use the power supply that came with it or, because it will take 9V, you've just wired it directly to the battery?

Hi. I wired it to the leisure battery with the appropriate fuse. Mine says 9-24v supply. I cut the plug off and soldered supply wires to it. I also have a switch to isolate it so I know it won’t be depleting the battery if the van isn’t used for a while.

 

[Ivor]

Hi. I wired it to the leisure battery with the appropriate fuse. Mine says 9-24v supply. I cut the plug off and soldered supply wires to it. I also have a switch to isolate it so I know it won’t be depleting the battery if the van isn’t used for a while.

Good shout with the switch. So you discarded the transformer that came with it as that's only needed for 240v supply right? Can I ask how you ran the audio and power leads? Sorry for all the questions, just helps me avoid mistakes where I can.

 

[CJW]

No problem.

Yes, since the unit is designed to run at automotive voltage, the mains transformer isn’t necessary.

Power goes from my LB to my switch panel, then to a fuse, then to the unit.

My rear speaker cables go to the main loom that runs fore<>aft above the passenger sliding door.

Power and speaker cables, once into the cabin area at high level, go above the cabin ceiling panel into the cubby hole.

Does that explain or would a sketch help?

 

[Ivor]

Ahi

No problem.

Yes, since the unit is designed to run at automotive voltage, the mains transformer isn’t necessary.

Power goes from my LB to my switch panel, then to a fuse, then to the unit.

My rear speaker cables go to the main loom that runs fore<>aft above the passenger sliding door.

Power and speaker cables, once into the cabin area at high level, go above the cabin ceiling panel into the cubby hole.

Does that explain or would a sketch help?

Hi there, me again,

I’m finally getting around to this, got all the bits needed and I’ve cleared next weekend to do this along with adding some additional lighting.
Can I ask; with the unit in the cubby, did you just drill a hole though to where the cab light sits and pull cables through there? Dropping the light unit out first of course.
Thanks in advance

 

[CJW]

Ahi

Hi there, me again,

I’m finally getting around to this, got all the bits needed and I’ve cleared next weekend to do this along with adding some additional lighting.
Can I ask; with the unit in the cubby, did you just drill a hole though to where the cab light sits and pull cables through there? Dropping the light unit out first of course.
Thanks in advance

Yes - it’s completely invisible once done.

 

[gazd]

Hi,this looks like an excellent set up,do you have a link to where you brought it from?I've had a look and can't seem to find the same one
Thanks garrie

 

[CJW]

Hi,this looks like an excellent set up,do you have a link to where you brought it from?I've had a look and can't seem to find the same one
Thanks garrie

I think this is the same unit with a new case design. Same manufacturer, same spec. I got the option with the power supply to chop the cable.

Pardon our interruption...

 

[Ivor]

I think this is the same unit with a new case design. Same manufacturer, same spec. I got the option with the power supply to chop the cable.

Pardon our interruption...

Yeah that’s the one I’ve got, I’ve tried it with a power adapter on 240v in the house and works a treat.
@CJW , you’ve chopped the plug on the power supply, it should work fine though with the right connector and a length of cable, in-line fuse straight to the leisure battery? Am I right?

 

[CJW]

Yeah that’s the one I’ve got, I’ve tried it with a power adapter on 240v in the house and works a treat.
@CJW , you’ve chopped the plug on the power supply, it should work fine though with the right connector and a length of cable, in-line fuse straight to the leisure battery? Am I right?

Almost:

Yes, since the unit is designed to run at automotive voltage, the mains transformer isn’t necessary.

Power goes from my LB to my switch panel, then to a fuse, then to the unit.