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.

2012-04 Music and Video

I really need to finish a piece of music.

I had a general idea and planned to keep it simple; Some autoharp mic'd up close so all the key bridge noises and fingers on the strings and creaks etc. would be picked up then add some short wave radio noise and some tabla.

Setup the mic's. Do a sound check with the electric guitar first. Like the sound. Try some delay effects. Like that. Add some more. Sounding quite good and a sequence of notes comes together quite well. Do a take. Sounds good. Add effects. Yum.

Now the video.

I wanted this to be about Autumn. Dig out photos of Autumn of Daniel's farm and some dead tree and park photos. Get the TV23 image scripts out and generate some scenes with them. Fire up a video editor and mix the stylistically best fitting ones together to the right length and add the sound.

Quite nice really.

Upload to Youtube. http://www.youtube.com/watch?feature=player_embedded&v=A6Fl3EMZd2U

2012-02 Digitise Video tapes

I've had a few goes at this. always a bit half-hearted but I'd like to get rid of the tapes lying around and I have a gruntier system then when I last tried so I'll give it another shot.

# ***** Done: *****
# size is good.
# deinterlace is acceptable.
# cropping - could be better.
# Selects the correct video input (instead of the TV tuner) Check the size and rate settings.
# output to file. - works without fram dropping on video only - test with audio.
# audio capture. - need to set the capture channel via alsalmixer.
# sync to keep sound in sync - no noticable drift in 10 min tests
# A format better: 10min = 270meg. Try audio compression too ? Great - tiny now.
# Cropping top and bottom looks a bit out too. - Better, good enough for now.
# ***** Needs: *****
# nothing really - some good long tests.
# find out why the grab is sometimes textured and a restart fixes it.
mencoder -tv driver=v4l2:input=3:alsa:adevice=default:width=768:height=576 -vf pp=lb,crop=768:560 tv:// -oac mp3lame -lameopts preset=medium -ovc x264 -x264encopts pass=1 qp=40 -o deathrace2000.avi

# Result:
# Works very well indeed with 927M for a full length video that looks as good as the original and can be viewed close to real time with mplayer so you can record as you watch.
# Outstanding issue:
# find out why the grab is sometimes oddly textured and a restart fixes it.
# Workaround:
# Check recording with mplayer after a few seconds. Restart if not right.

mencoder -tv driver=v4l2:input=3:alsa:adevice=default:width=768:height=576 -vf pp=lb,crop=768:560 tv:// -oac mp3lame -lameopts preset=medium -ovc x264 -x264encopts pass=1 qp=40 -o deathrace2000.avi

# Trim and crop:
# ***** Needs: *****
# Needs to be sped up
# Needs to preseve quality.
# ***** Done: *****
# Start time: -ss hh:mm:ss.xx
# End time: - t seconds or hh:mm:ss.xx
# Crop: -vf crop=width:height:x:y
# the -vcodec copy overrides any -vf - fix quality: Use another codec.

ffmpeg -i deathrace2000.avi -ss 00:00:50.00 -t 20 -vcodec libx264 -vf "crop=656:560:54:0" dr2000-02.avi

That's all a bit sucky: Just trim instead and use the player to crop if needed. So I can just go:

ffmpeg -i deathrace2000.avi -ss 00:00:50.00 -t 20 -vcodec copy dr2000-02.avi

Which is blindingly fast and preserves quality.

2012-01 Low Noise Phono System

I've always had a little hum on the record player. So low though that even quiet music obscures it.
However it is there and I recently got a copy of Tibetan Bells. TB is very quiet indeed, with long passages where a single bell note fades completely before the next is struck.

[1] Check the amp.
[2] Check the cables.
[3] Check the record player.

Amp:
Found the Tuner input on the amp, which I had been using had some hum. Checked them all: The Tape input is quietest by far.

Cables:
OK.

Record player:
Both check out fine.



OK, the pre-amp in the amp is noisy so I got a general preamp kit from jcar (http://www.jaycar.co.nz/productView.asp?ID=KC5159) to try. Cheap enough to discard if not good enough.
It sounds great. Housed it in an old power supply case and it goes directly to a spare input on the PC sound card.
I can easily hear the original tape noise kick in as the cutting engineer switches it in when mastering the LP on Tibetan Bells so the total noise in the system here is less then in the original studio (1970's analog) and there's no discernible hum at all. An added advantage here is there is no need to use any mechanical switches any more. I just use alsa mixer to directly control the sound-card input level and switch between inputs on the sound card.

Here's a photo of the finished pre-amp disguised as a pedestal.

2010-09 Stereo patch bus

Tired of plugging in various new devices for recording or playback. It's a chore and messy to the point where I'm deferring audio projects on account of it.
Some simple patch panels to allow selecting / routing inputs and out puts are needed.

2008-11 Concrete Record Player

So its to be a record-player then: The Op-shop had some mint diamond styli for a few bucks so I bought them.
My Trusty Luxman skates a little and is too wide for the lundia. I felt like an audio project after all the PC based stuff so the Concrete Record Player Plinth is the POTM.
At last a home for my SME arm. Here you see all the parts I've been putting aside: The bearing, light weight patter and motor from a turntable with a crap arm but completely noiseless and stable - can't recall the brand. All sorts of cartridges and styli collected over the years and of course the pice of tone army resistance: a SME tone arm. Cost me $100(ish) in the 80's from a greedy eccentric who only prized it's resale value.

2008-07 Video for TIM

I've been taking a few good photos and seeing some neat old films and I'd like to do something where the problems are creative instead of technical or mechanical so a video for TIM sounds good.

Sort out the track(s).
Sort out and idea for it.
Sort out the tech' to do it.

OK well, sorting out the track and the treatment were kind of linked:

Something short and fun perhaps?: I had the idea of doing a space travel track based on animating graphics from styled on 60's SciFi paper back covers and sketched up an idea but it didn't jell. Those graphic artists were great and I only really realized how great until I tried to copy their style. I still think I'll have a go but I need to mull it over for a while.

Something with a very clear and simple process?: A photographic temporal cutup for a jazz track was another option so I bit of thinking that through made me realize that I have an idea for another project that is too close to that and I don't want them to bleed together. (And I'd already done something quite similar to this for another of the tracks.)

It looked like the epic track was going to be the one after all. I'd been holding off on this trying to find a way of using Camus's The Myth of Sisyphus using a weird old doll . But I need a better blue screen then I have right now and photos and lighting etc. etc.... too much. So trim it down: Rhinoceros by Inesco sounded easier and it fits the track almost as well. I could re-use an older idea I'd had and just plonk Rhino heads on the narrators as the film continued.

Easy.

So that was it.

The process was quite obvious after that:
Generate backgrounds:
Generate Narrators:
Use kino to put the narrators on the backgrounds.
Use cinelerra to edit the scenes in sync with the soundtrack.

Backgrounds: I picked through one of my piles of freak newspaper clippings and scanned then clipped and resized them in gimp. I sorted the images in to categories then dug up the script I used for the TV23 stuff and used that to make some video from them.

Narators: These are from a set of photos that disquiet. A lot. Trimmed them, sorted them and made temporalfilms oif them with the TV23 script.

Edited a narrator to inject more of the soul of the image owner back into it with kino. Used a custom png file as a mask for a luma wipe and set the start and end to 40% or so to fudge the narrator onto the background.

Finally got enough cinelerra skill to layer the back grounds and narrators onto a soundtrack and did a test run. I think it looks good enough not to use the Rhinos. Cool. Just the grunt work to do now.

A week Later: A few hours work and the figures and backgrounds are all done. I need to composite the figures onto the backgrounds and then mix them in cinelerra. I've been playing with cinelerra a bit and dont get the interface.

2008-03 Mic pre-amps

I've been using an old cassette recorder for a mic preamp and it fulls up a slot in my shelfs, isn't portable and has a bit too much noise.

2008-02 Digitize VHS cassettes.

I have a lot of old SciFi films I'd like to get onto my media server and then a friend had some old tapes he wanted converted too so that made it a good project of the month.