Building a Small Stereo Boombox. Does this wiring layout look OK?

[LBKosmo]

Greetings to all!

This is my first DIY audio build and I decided to make a small stereo boombox that I can sit on a desk or table. It's going to use a Sure Electronics 2x8w @ 4Ω Amplifier board with a 50K Stereo potentiometer to control the volume, and two Visation FRS7-4 2.5" Full-Range speakers.

I just wanted to post up the wiring layout I drew up to make sure it all looks alright seeing as this is my first project and would like to do my best to not screw it up.

Thanks in advance!

 

[spwalek]

It looks OK to me. You may just have to increase the LED resistor depending on it's type/current rating.

 

[LBKosmo]

Thanks for the reply! I appreciate it. The LED will be a 5mm Green LED with a forward voltage of 2.2VDC/20mA, so 560Ω seemed right on the money according to the online calculators I queried.

 

[Mooly]

Many modern high brightness LED's can be too bright for comfortable viewing at only 1ma or so. Trial and error is the only way I'm afraid.

 

[LBKosmo]

Thanks for the tip. Much appreciated.

 

[Kip McGee]

You need to use a fairly large switch . Or a Relay . A smaill .5 amp switch will never hold up running the main power rail of the amp. you also need to add a fuse.

 

[LBKosmo]

I planned on using the following switch:

SPST Miniature Rocker Switch 060-670

It's rated at 6 amps @ 125VAC. What size fuse would you recommend?

 

[KMossman]

anyone else concerned about not having a star ground?

 

[KMossman]

What size fuse would you recommend?

3A SB

 

[LBKosmo]

Thanks!

How would you recommend implementing a star ground into this wiring? It will be powered by a 12V AC/DC Power Adapter and will only have a two-wire circuit.

 

[KMossman]

I see 3 wires for the signal, and 2 wires for the power, though there is the common ground.

For star ground, simply bring all the ground wires to one point. As it, I think there are 5 ground points, which raises the possibility of hum.

 

[LBKosmo]

So you're saying I should tie all the negative ( - ) wires to one point regardless that this is a two wire circuit and does not have an earth ground as would be found in a three-wire circuit?

 

[Mooly]

Beware that the speaker output marked - (minus) on your diagram may not be the same - as everywhere else. It may well be a bridge amp with floating load so don't connect the speaker - points together or to anything else.

The input grounds and PSU grounds (yes the - becomes "ground" in a single rail amp probably are the same point but check first before doing anything.

 

[LBKosmo]

Thanks for the information Mooly!

This is my first build so I appreciate the help from everyone.

 

[prezden]

Just a thought on your choice of the TPA3110 amp.
I have built small portables with this amp and the TA2024 and the TPA3122. The 3110 does not compare to the 2024 and 3122 amps (all from Sure). With a few mods the 2024 or 3122 can sound really good in a small portable. They both work well with a 12V Lion battery pack for portability. This of course is just one person's experience and others may have some different thoughts.

 

[Octavia]

Hmm Prezden, when you say the TPA3110 amp does not compare to the 2024 and 3122 amps can you be a little more specific as to what you find the differences to be?

 

[prezden]

The 3110 is 8W whereas the 3122 and 2024 are both 15W. Beyond the I'm not technically savvy enough to say. Sound wise at least to my ear the 2024 and 3122 have a much fuller, louder sound. I modified both the 3122 and 2024 with larger and better quality power caps.

 

[LBKosmo]

I plan on using Visation FRS-7 (Link) speakers and they are rated at 8W/15W Max. Would I be OK running these using either of these boards:

Sure Electronic's TA2024 2x15w

Parts-Express Brand TA2024 2x15w

 

[Octavia]

I've seen other comments on the TPA3110 being sonically better than the tripath. With efficient speakers 8w vs 15w shouldn't really mean all that much. I don't have any direct comparison although I have the dayton tripath with to me sounds quite good although not quite up there with my el84 tube amp. At $10 I think I'll pop for a 3110 and see for myself.

 

[LBKosmo]

I think I am going to stick with the TPA3110. It's nice and inexpensive, and I think will fit my needs for this small project. I've read it sounds great as well.