Little cheapo 10W stereo amp modules

[reelguy]

That's a good idea ! Thanks..

Peter W.....Reelguy.

[Yorkie]

I've made aluminium temporary front and back panels and mounted mine on a little baseboard (about 7" x 4"), and have fitted the stereo input sockets (RCA and 3.5mm), a power socket and spring-clip speaker sockets on the rear panel. It's functional, if not pretty! When I get time I'll probably make a nice wooden case for it and a front panel with lettering etc. For now, I've fitted some 'chicken head' knobs on which I had to hand. I'll keep a lookout for some small splined knobs some time which will push on/pull off.

It's a bit awkward to mount the amp as the PCB at the front protrudes further out than the threaded bushes of the controls, so I bent the front mounting panel to enable the controls to be mounted and to clear the PCB. I could possibly have got away with using two nuts on the control bushes to bring a flat from panel far enough forward to clear the PCB. (Further down the line, I may make a flat front mounting panel and see if it will give clearnace with two nuts per shaft.). At the rear of the PCB I drilled three holes through it the ground plane and made three 6mm diam brass pillars tapped 4BA with bolts through them to secure the rear of the PCB. Some pics attached.

I discovered that the two pole on-off switch on the volume control pot was open circuit - probably due to tarnished contacts from >30 years in storage. I drilled a 1mm hole carefully in the perimeter of the black plastic switch section on the rear of the twin gang pot as near to the bottom as I could- the 5 O' clock position looking at the rear of the pot. I squirted Servisol through the hole and worked the switch on & off several times which sorted it.

Just need to wire up the sockets now.

Other than that, I've been up and down ladders trying to tame a conifer hedge before the birds start nesting in it as they are threatening to do.

[Refugee]

The little amplifier looks like it would have been mounted with the track side of the PCB facing the inside top cover so that the volume control is on the right and the edge of the PCB would have been in a slot in the rear of the front panel.

[Joe]

Good job, David.

These are the knobs I used.

- Joe

[Yorkie]

Thanks Joe.

Oddly enough, I almost bought those when I odrered the speaker and stereo sockets from them the other day, but when they described them as 'push on', I didn't know if they were for splined shafts or shafts with flats on them. From what you say, I guess they'll be splined and thus, well suited. Neat little knobs in a range of colours and at a bargain price as with almost everything from Spiratroncs.

Ill get my order in!

[AlanBeckett]

You really pushed the boat out there on price yound Joe

Alan

[Daniel]

Not sure whether this thread is still alive but I thought I would comment to ask a question that I have been trying to figure out and hopefully one of you could help me. 1stly when I am working everything up ie 12V 2ah adapter from my box of many things electronical and some second hand speakers that I got from cash converters in my town centre for a 10er (quite a good set actually for the price) btw there  8ohm I think and 8 ohm or 4ohm tweeters not sure will double check. I plug everything in and turn it on I get the pop from the speaker like always but when I connect my phone and start playing bass heavy( ish) music  I get a real amount of distortion even when I adjust the bass and treble pots seems to me a little better but not much.

• Is 2ah enough for the little amp (contacted Chris at bardwells and he said the maximum current draw would be 400mah at full pelt (volume) so I thought it would be fine on 12v 2ah considering the amp goes from 6v-24v.
  
• Am I using the correct speakers because I'm placing the amp in a potable system that I am building which will also be housing a 12v 2600mah rc NiMh battery attached to the amp as well ( via double pole switch on.off.on) so that I can run it on a mains  a.c.to dc adaptor and charge the batterys or run it on battery on its own.
  

Please could someone help I would be so gratefully 

Thankyou Daniel

[Mark Hennessy]

What do you mean by "2ah"? That's a battery specification, not a power supply specification. Do you mean 2A?

Don't worry about speaker impedance. Those numbers are very approximate; impedance varies wildly with frequency.

Most likely, you are driving something into clipping. If you have an oscilloscope, it would be easy to verify whether that's the case, and indeed, whether it's the phone or the amplifier. A partial cure to the latter would be to raise the supply voltage (read the datasheet carefully), but actually, you could just be expecting too much from it - especially if the speakers are decent quality hi-fi speakers that tend to be inefficient.

Some care is needed when working with rechargeable batteries. Lithium types are obviously the scariest, but NiMh types also need to be treated with respect.

[Refugee]

• Am I using the correct speakers because I'm placing the amp in a potable system that I am building which will also be housing a 12v 2600mah rc NiMh battery attached to the amp as well ( via double pole switch on.off.on) so that I can run it on a mains  a.c.to dc adaptor and charge the batterys or run it on battery on its own.
  

Please could someone help I would be so gratefully 

Thankyou Daniel

Does 2600ma rc mean that an old remote control model battery is being used?
Model batteries usually have a very hard life and will have nothing left for anything more than a small LED lantern.
You need to test the fully charged battery with a volt meter and a car bulb to see how much the voltage goes down on load.

[Daniel]

Yes I meant to put 2a I will be using a 2a psu and yes sure I may be expecting a little to much from a tiny amp but I've seen post where people have ran them at 9v and they said they sound brill is that still the case. And I'm not sure of the speaker specs I will have to check and get back to you when i get home as out atm. And as for the batterys I will be using an rc battery that I got from eBay because I have seen you tube videos of someone building a speaker and using the same one I order for theres and it work brilliantly and into to be careful of batterys I'm using the rc one instead of s sla because of weight and size