2015-12 Repair Solarvox speakers

This was to be an easy one. HA! Anyway... I have a number of HiFi speakers from the '60s - '80s and they take up space. Sorted them out and found this pair have a sound I like but a blown tweeter.

The label on the back is interesting...

I found an appropriately rated tweeter from JayCar and fitted it. It sounded very very bright. A series resister would be all that's needed to reduce the level of the modern more efficient driver but doing that by listening and changing the resistor seemed fraught.
I decided to try measure it :

• Make sweep and noise files and play them  on the left then right channels
• Use the Tascam recorder to grab a recording 
• Have a look at the spectrum of the recordings and adjust until they match.

Generate tone:  sox -n sweep1.wav synth 10 sine 10-20000
Generate noise:  sox -n wn1.wav synth 10 whitenoise

Then play it back and record it on the tascam.

Script:

while true ; do for F in *.wav ; do echo "Playing [ $F ]" ; play $F ; sleep 1 ; done ; done




Note the rug on the chair to create a special sound proof recording area.



After some trial and error the spectrogram of white noise seems the best way to see what's going on. Got these from
sox infile.wav -n spectrogram outfile.png
after trimming the tascam recordings down to just the white noise burst.

This is the new tweeter 

This is the original.













An 8 Ohm resister seemed to be about right:

I did both speakers as the high end is clearly better.

2015-09 Line out for the Yamaha CN-70

I got this for $30 or less. I have the room right now and it seemed in good nick and is. I removed an odd mixer that had been added but came without its power supply so was useless. I had been hoping to use it for a line out. (The organ is very well built for service).
That got me thinking about adding a line out. Found a circuit diagram. Found some room on the side panel. Had the parts.

Test Point 82 clearly indicated on the main board is just before the Expression peddle and the main Vol so that's about right. Drilled a hole and made a plate to hold a 6.5mm jack socket.

Mounted it, soldered it up and tried it out.

Noisy but good. I think the way to fix the noise would be to go back toward the tone banks, make a low noise amp and pick it up from there. There'd be no rhythm or auto play stuff that way though but I was toying with giving them their own outputs anyway. Maybe later.
Sounds AWESOME through last months PTOM (a spring line reverb tank reverb. must write it up). Very Marty Rev 

2015-02 Control surface for audio processing

I've been considering a sound processing language for a while. Looked at supercollider and liked it but never really did anything with it. Tried again recently and found chuck. I had a play and liked it. Not sure why I prefer it but it's something like: less elegant but faster to code.
The missing bit was an interface so effects and apps writen in chuck could be conveniently controlled during performance or production.
Found interface.js which can use OSC to send messages to any osc aware system/program (which chuck is) and has a constrained but easy to use way to build a panel of controls. These panels are accessed as web pages served by an included server so a tablet can access it.
Presto:  The knobs, sliders and buttons are all touch sensitive on the tablet and you have a versatile touch sensitive control surface that can talk to chuck.

Details follow:

Notes on installing chuck.
I use Fedora both 20 and 21 on two different machines with the CCRMA repo (CCRMA fed21 repo here) with:

       sudo dnf install chuck
       sudo dnf install miniaudicle

The standard packages seem OK.  ( I did build from source to try to fix the windows in miniAudicle not remembering their locations between sessions: got bogged down in QT, but the build was process was reasonable )
The way I use it is to start  jack (with qjackctl) then run miniAudicle.
You'll get an IDE, a console window (shows error, information and print type debug messages) and an execution control window (called Virtual Machine). Like this:

The doc's are a bit out of date for the osc stuff but  these examples are current and will set you right.
You start the virtual machine then use the IDE to edit and run code. Lots of good examples to play with in the link above. (you don't have to use jack: there's  miniAudicle-pulse and miniAudicle-alsa if it suits you better)
Update: Nearly there. A bit stuck on the OSC stuff and chuck keeps locking the osc message stream. Nuts.

2015-01 7" record boxes

I have kept my LPs well sorted and it pays; You can find things and duplicates show up so you can keep the best LP.
But 45's have lived in stacks unsorted except of a fav's pile.
No more.
The mid shelf of LP store was always put aside for 45s but getting boxes ? I could not do this. Nothing was the right size, so I must make some.
Got some thin and strong cardboard boxes from the recycling at work, some cutting and hot glue and here they are:

I made them the same depth as the shelves and just wide enough so that 5 fit on each shelf. Much denser and more accessible too.
Freed up a bit of much needed space so now I get to move the LPs around to make room and then sort the 45's into categories I guess.

• Cut the box into sections.  1 for the front, 1 for the back and one for the bottom and sides.

• 
  

  I use a cutting mat and box cutter to make the parts. To score the bends I used the end of a median paint brush. Be careful to crush but not cut the cardboard.
• Hot glue the parts together.

Box cut into sections for parts