Cheap/DIY bluetooth amp for old bookshelf

[cooolsunny]

Guys I have a pair of old Philips bookshelf speakers (impedance 6ohm), they were part of an old hi-fi music system. Now I am thinking of converting these speakers in to a Bluetooth enabled system. so I need advice on how that can be done on a budget.

specs of original amp that was driving these speakers were --
output - 2*25w rms
snr > 67dba
frequency response 80-15000 hz

i found that this can be achieved in two ways:
1. buy a cheap amp like lepai and add a Bluetooth receiver. total Cost approx. 5200
2. buy a bluetooth amp board like this TDA7492P 50W+50W CSR8635 Bluetooth 4.0 + a 12 volt 5 amp power supply. total cost approx. 1800

so now i want suggestions from audio gurus/ diy experts about these options. whether the second option work and if it will work will it be able to match original systems sound quality.
is there any other option that i can use. i am open to change them to two separate mono blutooth speakers.

sources that i am using are pc, win phone, ipad, android phone.

PS. i want to do it as cheaply as possible without compromising on sound too much. and i am not electronics expert but willing to learn and experiment if parts are available easily.
PPS. i have unused laptop adapter 19.5 v 4.5 amp, an atx 400 watt power supply and access to parts inside the old amp like transformer, caps etc. if any of these can be used to power the board.

 

[greenhorn]

I think that option 2 should be fine - the board i see online seem to support 8-24V, so the laptop adapter should work fine as a PSU

the bluetooth adapter may be the weak link - most of the cheaper ones I've seen are rather ordinary sounding. (are decent, but not exceptional - ok for that budget range)

matching the original system, probably may not happen, but you will come pretty close for a fraction of the price

 

[cooolsunny]

I think that option 2 should be fine - the board i see online seem to support 8-24V, so the laptop adapter should work fine as a PSU

the laptop adapter I have is a cheap Chinese one. will it cause white noise or distortion.
and the power supplies available for 500 rs or so, are they better then this adapter.
plus I found Nobsound Hifi Mini Bluetooth around 4k. any views on this.
BTW thanks for taking time out for answering.

 

[regeHA]

Not into DIY, but instead of BT why not go wireless with something like Chromecast Audio. Handles more than MP3s and makes for better quality up to 24/96. Plus, you get tons of audio stations too.

Budget amps I've heard Topping and liked it, but not sure how it compares DIY though.

 

[greenhorn]

I'd say buy the board - they seem to be 1.5K INR or so. and see if the adapter makes any noise. if yes, they we can worry about the psu upgrade then.

these Chip amps have very decent supply voltage rejection ratios, so should be able to manage.

 

[cooolsunny]

thanks for the chromecast idea regeHA, but it will take the cost higher and I can always add it later.
@ greenhorn this is also available TPA3116 + CSR8645, this board has more power and better Bluetooth chip. Somewhere else I found that csr8654 supports APTX. any views?
although there are some youtube videos about tpa3116 distortions but only 1 or 2. either the board is not famous or bad enough to warrant more videos.
thanks for replying

 

[z@m]

If you're willing and able to tinker, go with option 2!

IMHO, a Lepai amp doesn't offer better sound quality than the board in question.

Images of the board on Ebay seem to indicate that it has a 3.5mm stereo input jack. So in the event that the on-board bluetooth adapter doesn't impress, you can always connect a separate receiver later on. Logitech sells one such for ~1k INR.

Good luck!

 

[greenhorn]

most of the common versions of this board don't seem to have aux in
make sure the one you're buying does

 

[cooolsunny]

most of the common versions of this board don't seem to have aux in
make sure the one you're buying does

I can't find any board that supports Bluetooth and aux in both. there is one SMAKNA 3116 board that has aux in but that costs 5500rs.

any views on TPA3116 + CSR8645 board. does it support aptx.

and is it advisable to order from banggood, 7492 board cost just 799rs there .
@ greenhorn I am going to be certified member of your Cheapskate Audiophile Society .

 

[greenhorn]

I can't find any board that supports Bluetooth and aux in both. there is one SMAKNA 3116 board that has aux in but that costs 5500rs.

something like this
TDA7492 50W+50W CSR8635 Bluetooth 4.0 Audio Receiver Digital Amplifier Board AUX-in Integrated Circuits from Electronic Components & Supplies on Aliexpress.com | Alibaba Group

yes indeed. you are not far from enlightenment

 

[tnvijay]

There are a number of USB Bluetooth mp3 boards. Costs around 400. They are very good sounding, if it's used with a preamp before poweamp.It's widely available in most
electronic shop. it has a aux input also. You can consider TDA2050/LM1875 STEREO AMP ,from eight audio, India.Costs around 200. If you can use the existing trafo and. build a decent dual power supply, you can easily get a good music system, within 1k. These cheap Chinese decoder modules are not to be underestimated, just by their cost

 

[Audiodoc]

You can buy the avantree bluetooth transmitter cum receiver for around 3000 and add a good class D amp. The avantree supports aptx which is better than a2dp of common bluetooth receivers and you can use it with other equipment too.

 

[cooolsunny]

You can buy the avantree bluetooth transmitter cum receiver for around 3000 and add a good class D amp. The avantree supports aptx which is better than a2dp of common bluetooth receivers and you can use it with other equipment too.

I have an ipad 3 does that support aptx. I think the source should also support this codec. am I right.

 

[cooolsunny]

There are a number of USB Bluetooth mp3 boards. Costs around 400. They are very good sounding, if it's used with a preamp before poweamp.It's widely available in most
electronic shop. it has a aux input also. You can consider TDA2050/LM1875 STEREO AMP ,from eight audio, India.Costs around 200. If you can use the existing trafo and. build a decent dual power supply, you can easily get a good music system, within 1k. These cheap Chinese decoder modules are not to be underestimated, just by their cost

are these 2050 and 1875 based amps are better then 7492/ 3118 boards that are available with Bluetooth. can you link me to some article where I can learn about building power supply using old components( I have never made anything electronic but I know what is a transistor and what is a capacitor or resistor)

 

[Audiodoc]

I have the iPad 3 unfortunately it does not support aptx. However my samsung s4, s6edge, tab s and note 10.1 does. The avantree is the best bluetooth adapter that I have definitely better than the logitech one.

 

[greenhorn]

another cheap option if you can buy from abroad
Stereo 2.0 Nobsound Mini Bluetooth 4.0 Amplifier Wireless Receiver HiFi Digital Audio Player for phone/tablet/TV/Computer-in Amplifier from Consumer Electronics on Aliexpress.com | Alibaba Group

 

[cooolsunny]

another cheap option if you can buy from abroad
Stereo 2.0 Nobsound Mini Bluetooth 4.0 Amplifier Wireless Receiver HiFi Digital Audio Player for phone/tablet/TV/Computer-in Amplifier from Consumer Electronics on Aliexpress.com | Alibaba Group

this is what I asked you about in one of the earlier post. this sure looks good.
I am thinking about ordering 7492+bluetooth board. that is the cheapest and most common solution currently.
is it advisable to order from aliexpress or banggood instead of ebay.in. it will save me around half the money.