Well, not much going on but the rent really but I’ll try and muster up something of interest though still find it peculiar anybody could be interested – hey!
I’ve built a pair of loudspeakers. From a flat pack kit. The idea is to use a 4” full range driver and use a low powered amplifier, preferably valve to power them and reproduce the full frequency range.
To my mind it almost works but I added a pair of tweeters to enhance the top end and their contribution is subtle but noticeable.
The 4” drivers are Mark Audio CHP70’s and the guy who supplied the flatpacks cut the baffle with a recess to take these drivers. I opted for the cabs in 18mm birch ply but could have have gone for MDF, which is cheaper.
I originally had every intention of spraying them matt or satin black but I like the look of the wood so much I am now going to coat them with about six coats of clear acrylic satin varnish after giving them a very good sanding.
When I assembled them I didn’t really have enough clamps but muddled through somehow, I borrowed the clamps in the pix from Dave The Bass, occasional forum member here.
Here’s some pix:
And here’s how they can look in black or white:
So how do they sound? To my ears, very very good and they’re sounding better as they become ‘run in’. They won’t be to everybody’s taste and will not overpower you with bass but the bass is there and it’s tight and controlled.
Seperation is really good and all detail is there. They sound best with acoustic and classical music and some light jazz as well but I’m listening to rock music on them ok.
They are mounted on outriggers for acoustic isolation, I made those from 30mm x 6mm metal strips from Wickes and secured them to the cabinet bases with M8 threaded inserts and bolts. They sit on black coned spikes. I have tried them with and without acoustic foam and to my ears they sound better without.
I’m surprised they sound as good as they do as apparently they suit being placed in a corner better and as you can see mine back on to a curtain behind of which there is a double glazed window in a sliding door.
They are powered with a 10 watt a channel push-pull valve amplifier I made around 26 years ago from an Elektor magazine design. Now just waiting for the weather to be bright and sunny for a couple of days so I can sand and varnish them outside.
When I get some more money I hope to build a pair of single ended valve amplifiers which apparently sound better than my push-pull (two output valves) arrangement.
Oh, forgot to mention, the ‘super-tweeters’ as they’re known, are fitted with a 3.9 ohm 5 watt wirewound resistor in series and an 8 ohm 5 watt wirewound resistor in paralell for power attenuation and a 1.5uF polypropylene capacitor in series with the ‘live’ side of the signal path to filter out bass frequencies.
They are constructed from a Post Office cardboard poster mailing tube fitted at the front with a plywood ‘donut’ glued in place and the tweeter is mounted on this. The base is made from lengths of broom handle and large wood nails and the whole shebang is sprayed matt black.
Some links:
Cheapo mdf horn cabinet ready built, not really recommended:
Frugel Mk 3
Attenuation calculator:
Power me down baby
CHP70 full range driver, this is where I bought mine from: (Edit: This link only goes to home page for some reason but the speaker is in there if you're interested)
CHP70
Super tweeter, I bought mine from here, Canada:
Tweet tweet
To accompany my system I have redesigned my audio switcher. Mine has five inputs and no rec out facility. A friend of mine has compiled a PCB that allows for six inputs and rec out where the phono sockets are mounted directly onto the PCB and the whole thing is then mounted on the case rear panel.
I did make a six channel switcher on veroboard but although it worked, the extended layout of components introduced some hum. I’m going to try and cure it but this seems like a better idea.
Here’s a few pix of progress with a PCB printout stuck with Pritt glue to the rear panel. The transformer was one I had lying about and the power supply board is a kit from Maplins, cost a tenner and can be adjusted between 2 and 30 volts. I have it set to five volts and this will be used to operate the relays that switch audio signals:
Just waiting for Fat Guts, aka as Fattus Guttus or ‘Slim’ to finish making the PCB now.
Next up, me plantz. Haven’t posted any plant pix lately. Some of you may remember my Yukka plant but we had a real bad storm in April and it literally blew the top off of it. A headless Yukka plant corpse is now reported to be roaming the streets of Greenwich town at night terrorising tourists and muggers alike, which is possibly a good thing.
Other than that I’ve had problems with leaf munching. Whatever’s chewing big chunks out of my plants has spread and it now affects 4 or 5 plants. I thought it was leaf cutter bees (thanks for the suggestion TC
) but I’ve only ever seen one or two bees that match their description all year. Also, no ants were spotted this year.
In an attempt to stop it I sprayed the affected plants with bug spray which I absolutely hated cos I probably killed some spiders and I like looking at the spiders. Since then, problem seems to have stopped but this may just be due to the onset of winter and bugs having a kip til Spring. Or whatever bugs do in winter. Die?
I did find a small green caterpillar about a week ago, now wondering if maybe I have a whole host of these and they’re the culprits, here’s a pic:
I’m considering buying some netting and covering the affected plants just before Spring to see if that stops the damage, not sure yet.
Here’s some pix of all plants as they are, taken today, with some close-up shots showing the damage. Note that the fresh leaves on the tree plant, which only recently appeared, have not been eaten at all.
This first pic shows a plant named Coleus, Gay’s delight (no snickering back there) and a week ago it was full of foliage but now most everything’s dropped off leaving mostly just those two big stems. Wondering if this is normal for winter or whether it has the lurgey.
Leaf munch:
These are the boots I was wearing in me Glastonbury pix from 4 years ago, they finally gave out, split leather upper where it joined the sole.
Leaf munch:
Leaf munch:
Other things, recently fitted a sound mixing desk to a theatre within a school and whilst I was there the class change pips clock went up the chute so I shot over to my suppliers at Bow, copped one on account, zoomed back and installed and programmed it. School was happy cos Ofsted inspectors were in and they urgently wanted their class change pips signals to work. Sometimes I just get lucky like that. But that’s been the only work of note I’ve had in several months.
Sophie offspring now settling into her role as a teacher and gaining confidence but says it’s very hard work, extending into the evenings often.
I had been looking for a juicer cos I really don’t get enough fresh fruit and veg and I thought if I could juice up some carrots, spinach and stuff and slurp it down it would be good for me. Cruised Comet and they didn’t have a one. Looked online, they all seemed either crap or too expensive.
Then lo and behold (oh look, a star in the East they exclaimed) (oops, sorry, wrong celebration) itsme was floggin’ one. So I bought it. And it works. I have made some orange juice. But bloody blimey, what a lot of hard work for a glass of orange juice, lol, half a litre of juice, three tons of washing up. Oh well, tis good for me
Talking of juicing (did that sound rood?) when I see those commercial machines in Airports, holiday resorts and houses of ill repute I notice they put whole oranges in the machine. This juicer manual says remove peel and pith – your views, oh knowledgeable peeps? Whole fruit or not to whole fruit?
And lastly, to end on a sad note, my good friend Johnny Foster has bowel cancer. He’s about 69 or 70 years old and he told me ten days ago of his biopsy results. Oh fek.
He’s going to undergo chemotherapy, radiotherapy and possibly surgery at the local Queen Elizabeth Hospital. I would have preferred for him to be treated at Guys & St Thomas’ Hospital, who done the deal for me, but that’s the way the cookie crumbles I suppose. Maybe Guys only do certain types of cancer.
Johnny, here’s lookin’ at you kid, I’m routing for you, good luck.