Stereo Amp/Speaker kit into one pair of speakers

[tomdoughty]

I'm a beginner so please be kind and straightforward.
Building a Bluetooth Speaker from a kit but only using one Woofer and Tweeter.
The kit is a C-Note bookshelf speaker (stereo) and the Amp is a Dayton Audio KAB250v3. So the amp has 2 sets of speaker leads, but I will only be using one tweeter and woofer. I have built the crossovers, but want to know how to wire the speaker from the Amp without causing any amp damage. Should I just pair the -ves together and do the same with the +ves or do I need to build a stereo/mono converter? thanks! Tom

 

[dangus]

Something bad may happen if you wire the speaker leads together. Now, if that's a class-D amp, some of those amp chips have a mono mode where it is OK to tie the two channels together and drive lower impedance loads. You'll have to ID the amp chip, locate a data sheet, find out if it has a mono mode, and how to enable that, then solder to some tiny IC pins and/or cut some traces. It should be OK to leave the unused outputs unconnected, but you should modify the amp to sum the L and R outputs from the BT receiver to mono. If your amp is like the BT amp module I got from Banggood last year, the BT receiver is on a sub-board with pins conveniently labeled. Cut the L and R pins away, then solder resistors (10k to 47k, not critical) to the L and R ouputs from the BT receiver, then twist the free ends together and solder to an input pin on the amp portion. It might be reasonable to do something with the unused amp input, like tie it to ground through a resistor, or directly to the other amp.

 

[tomdoughty]

Class d?

thank you Dangus et al.. Yes, it's a class D Amp and I traced this so far. Bit of a riddle... KAB-250v3 2x50W Class D Audio Amplifier Board with Bluetooth 4.0
Quick Overview
The Dayton Audio KAB-250v3 Bluetooth Amplifier Board makes it quick and easy to add audio to your project, speaker build, point-of-purchase display, kiosk, or any location where music or sound enhances the experience. With an output of 2 x 50 watts, there is more than enough power to drive stereo speakers, yet the board is small enough to integrate into nearly any project.
Product Highlights
Efficient 2 x 50 watts of power from the Texas Instruments TPA3116 amp chip
Bluetooth 4.0 with aptX built directly into board -- no need for a separate module
New for v3 is a U.FL IPX coaxial connector for internal or external Bluetooth antenna (internal antenna included) and a Bluetooth pairing reset switch
Wire harnesses make installation quick and simple with no soldering required -- includes power and speaker cables
Separate ports for powering by battery or direct DC input from a power adapter
Optional accessories expand functionality and more
5-year Dayton Audio warranty

 

[rabbitz]

Maybe KAB-100M or KAB-60M would be more suitable as they are mono. Have no idea if they mix input stereo or Bluetooth to mono.

 

[tomdoughty]

thanks. Sadly, I already have the amp. I'll have a re-think. Just thought there would be a way of routing output from stereo into mono, simply and addressing the impedance with resistors. bugger!

 

[nigelwright7557]

you could invert channel 1 input into input 2 and then bridge the outputs.
if you speaker impedance is twice amps normal output impedance.

 

[tomdoughty]

impedance

Hi Nigel, I'm chuffed to hear a more simple sounding attempt at sorting this out. the amp board resistance is Supported Bridge Tied Load(Min)(Ohms) 3
and speakers are woofer 8ohms tweeter 4ohms. Now; presuming our idea is compatible , please would you guide me on what to do...? thanks Tom

 

[nigelwright7557]

Here is simple bridging circuit.
speaker connects to channel 1 output and channel 2 output.