Some years ago I was given a ten inch speaker which had been used as an extension from an Ekco A144. It was mounted to an odd-shaped piece of wood as it had previously been built into some panelling.
Despite having no use for it I hoarded it as I knew it was low impedance and if I ever did need such a thing it would be very difficult to get another.
I dug it out while working on my Pye and I then decided it was worthy of a case and from there it was but a small step to adding an amplifier.
Electronically it's nothing to shout about, being based on an LM386 IC. Power is from a transformer out of an old PIR flood-light put through an LM317. There was no danger of its voltage raising to a harmful level but the regulator is an easy way of getting rid of hum.
Here's the finished circuit-board and a front view of the case. The latter isn't fully completed as it needs a finish coat of paint and the volume pot will need changing as the current one is the wrong value, 50k instead of 10k, and isn't in the best of health either.
This picture is of the control panel featuring the mains switch at the top. Below that are switches for gain, either 20 or 200, and what is supposed to be a "Bass Boost" but is more like a top-cut to my ears. The sockets are a mono input, a stereo socket with mixing resistors and the bottom one is directly connected to the speaker and putting a plug into it disconnects the amplifier.
The other outstanding job is the fitting of a back but that can wait until I sort the pot. I'm wanting a few for other jobs so will be getting an order off fairly soon. At least it gives a chance to show the interior layout.
It's been an enjoyable job and most of the interest has been in the wood- and metal-work. I can certainly sympathise with Col over the quality of plywood and I wasn't trying to get a particularly good finish - if things had gone better on that front I would have French polished it. No, Col, I am NOT going to veneer it; it's a workshop 'Tool' and should look as such.
I've taken inspiration from Col and David but didn't try to aim for their standards. That said it's far better than the lash-ups I normally produce (they are often literally lashed-up with tape and bits of wire) and at least I'm not ashamed to show it off.
I'll shortly be building a simpler and smaller battery-powered version.
Cheers
- Joe
Despite having no use for it I hoarded it as I knew it was low impedance and if I ever did need such a thing it would be very difficult to get another.
I dug it out while working on my Pye and I then decided it was worthy of a case and from there it was but a small step to adding an amplifier.
Electronically it's nothing to shout about, being based on an LM386 IC. Power is from a transformer out of an old PIR flood-light put through an LM317. There was no danger of its voltage raising to a harmful level but the regulator is an easy way of getting rid of hum.
Here's the finished circuit-board and a front view of the case. The latter isn't fully completed as it needs a finish coat of paint and the volume pot will need changing as the current one is the wrong value, 50k instead of 10k, and isn't in the best of health either.
This picture is of the control panel featuring the mains switch at the top. Below that are switches for gain, either 20 or 200, and what is supposed to be a "Bass Boost" but is more like a top-cut to my ears. The sockets are a mono input, a stereo socket with mixing resistors and the bottom one is directly connected to the speaker and putting a plug into it disconnects the amplifier.
The other outstanding job is the fitting of a back but that can wait until I sort the pot. I'm wanting a few for other jobs so will be getting an order off fairly soon. At least it gives a chance to show the interior layout.
It's been an enjoyable job and most of the interest has been in the wood- and metal-work. I can certainly sympathise with Col over the quality of plywood and I wasn't trying to get a particularly good finish - if things had gone better on that front I would have French polished it. No, Col, I am NOT going to veneer it; it's a workshop 'Tool' and should look as such.
I've taken inspiration from Col and David but didn't try to aim for their standards. That said it's far better than the lash-ups I normally produce (they are often literally lashed-up with tape and bits of wire) and at least I'm not ashamed to show it off.
I'll shortly be building a simpler and smaller battery-powered version.
Cheers
- Joe
