Archive for the ‘how to’ Category

Primer: Pitch-Bending a Walkman

January 24, 2008

Welcome to the first in a series of posts where I will highlight a specific technique I have learned and instruct you on how to to the same yourself. This first one is on pitch-bending tape recorders. There a couple ways to go about this, but i’m just going to outline my preferred method here. Firstly though, here’s a list of what you will need to do this project.

    1) A soldering iron/solder and some experience in using it. Radioshat ones are ok, but usually have a very large tip, all will be much easier if you get a nicer pencil tip iron from one of your many friendly online electronic parts dealers.2) A cheap walkman. The one pictured cost 5 bucks. Go to your thrift store. The early nineties models are great and really simple.

    3) Some hook-up wire. Either get it at Radioshat, or if you like scavenging stuff, buy and old parallel printer cable, cut off the ends, slice ‘er open and harvest the wire. It’s typically multi-colored, stranded, and thin, all good things. Plus you can get like 36 yards of it from one cable, that costs fifty cents at the thrift store. Not bad.

    4) A potentiometer, or pot for short. This is a bit more difficult. If you are not already an electronics nerd like me, you probably don’t have 100 different kinds of these just laying about, so you will need to get one. Hopefully you have something better than Radioshat near you and you can go and get a few different types for cheap, or, search for grab-bags on ebay. If you are anything like me, this will not be the last electronic project you do, so the leftovers will come in handy. The unfortunate thing about this project is that the pot you will need is entirely dependent on the walkman you have. The general range I have seen in pot values between walkmen, is anywhere from 2k to 10k. If you can’t find out, I’d go for 5k and hope for the best. Or if you happen to have an multimeter, you can measure what size you will need.

    5) Some kind of drill. A dremel would be best as they tend to have a bunch of bits, which is handy, but you could get by with a regular drill.

    6) Wire strippers/cutters. You can get by without these, but it will be easier with them.

    7) A desoldering system of some sort. I use a solder-sucker from Ratshat, but you can use whatever you like.

Ok, lets get started. Firstly, you will need to open your walkman. If you chose your subject well, removing the back panel from the walkman will expose the circuit board, solder side up, like the drawing below.

walkman with the circuit exposed

Once you have exposed the circuit board, look for a pattern resembling the three solder points (yellow dots on the image) in the highlighted area above. They will always have a hole in the center of them, as shown, and if you look through the hole you will see an object with a small slot, the size of a mini screwdriver blade in it. This is a miniature trimmer pot. Those three points are it’s three legs, which correspond to the three legs on a full-size pot.

potentiometertrimmer potentiometer

Desolder the mini-pot and remove it from the board. You will most likely need to remove the circuit board to do so, so be careful that in doing so you don’t dislodge any important components. Once you have dislodged the mini-pot, examine it closely to see if it has any indication of it’s resistance printed or stamped on it. This marking could be extremely small, so look close. If you do happen to find a marking, take note of it, and if you can, buy the same value for your new full-size pot.

Now you will have three empty solder pads on your circuit board. Cut three 5 inch or so, pieces of wire and strip an eight of an inch or so of the shielding from either end. Twist the ends some to “braid” them tight, and then coat them in solder. This will ensure a solid connection to the board. Now, insert the end of one of the bits of wire into one of the holes and solder it to the pad. Repeat this for the remainder of the wires. You should now have three bits of five inch wire sticking up from your circuit board. Take note, or mark the wire that connects to the furthest of the three solder pads from the others, this will be the middle lug of your pot.

Side note: Sometimes one of the solder pads has a resistor connected to it. If your walkman has one of these, test bypassing that resistor and soldering in front of it in the series, instead of directly to the corresponding solder pad. On walkmen that have had this feature, I have found it to greatly increase the pitch range of this mod. I’ve had some that had a speed range from nearly “fast-forward” speed to barely moving.

Now that we have established connections to the board for your pot, we need to find a good place to mount it. This can be quite tricky depending on what walkman you have. I have found that often the cheaper the walkman, the less sophisticated the circuitry, the more room under the hood. You may have to get creative with your pot placement, but be careful to check that when the pot is in place it is not inhibiting any of the other functions of the walkman. I can’t tell you how many times i have installed pots and then realized that once they are in there the case can’t be closed. Trust me, it’s a bummer.

Once you have made a place for the pot, solder the three wires to the three legs of the pot. It will help to make a solid connection, if you first coat each leg of the pot with solder. remember, that the wire coming from the furthest solder pad from the rest (the furthest right in my image) gets connected to the center leg of the pot. The others can be connected as you like, but i usually like to make it so that when i turn the pot right the motor speeds up and when left, it slows.

Now that your pot is connected and functioning, mount it in the spot you made for it, and seal the walkman up. Congratulations, you just pitch modded a walkman!

For even more fun, you can do the same mod, but instead of using a mechanical pot to replace the trimmer pot, you can use a photoelectric cell. If you have never heard of one before, they are potentiometers that look like very small solar panels and react to light. They sell these as grab bags at Radioshat. If you’d like to try this, it’s a bit easier that modding with a mechanical pot.

photoelectric cell

To use a photocell, just connect one leg of the photocell to the solder pad furthest from the others in the pic I posted and the other leg to one of the other of the three points i highlighted. Only one will work, and it depends on your walkman which it is, but there are only two options, so I’m sure you’ll figure it out. This kind of mod makes a sort of tape driven phototheremin. Record some tape loops of drones and play it by using your hand to shade the photocell.

This concludes our first Primer, I hope someone out there finds this useful. Please feel free to ask questions in the comments if something’s not clear.

Oh, and of course there has to be a sound sample! This is a few tracks of various tapes being played on the pitch-bent walkman that I layered up. Enjoy!

- Pitch-bent walkman

Wonders of the cassette tape loop, part 3

January 20, 2007

A couple of weekends ago, my wife and I had the rare opportunity to spend a saturday together (she generally works saturdays). Of course it had been a while since we had been to one of our favorite thrift shops “The 2nd Mile Center” and eaten at one of our favorite middle easten eateries “SAADS” so we decided west philly was the destination.

2nd Mile is often a dead end, but sometimes looking around is really the fun part. This particular time went like most others, in that I didn’t really find anything as I made my usual rounds. Until… I was about to walk out, when I noticed a familiar shape. The shape of a cassette four track!

I owned a tascam for a while, but never really used it due to it’s overwhelming complexity. This one however, was one of the small low-end Fostex models. And, for $20, it was worth it even if all I ended up with was parts.

Fostex Four track

It had been a while, but I knew I had read about using these machines with loops. So I searched around a bit and finally found what I was looking for. The gist of it, is that you have a loop cassette and four tracks, that means, four loops running at once. And, you can punch in, so you can build loops on the fly. With the fostex, it’s even better, because one flick of a switch routes whatever input you are going in to, to whatever track you want to record to. So it could even work as a live performance tool.

I just got around to playing with this thing today and I can see why someone brought it to the thrift store. The pots short out, the jacks short out and it has some other issues as well. For me though, none of that matters as I’m not going to be using it to record my new pop punk combo.

So I sat down with a freshly spliced loop cassette in hand and started fooling around.

Cassette Tape Loop

I immediately saw potential in this set up. The tracking sucks, which adds great wow and flutter effects. It overdrives easily too. The first bit of sound i put in came screeching back sounding like something out of a horror scene in a sci-fi movie. This thing mutates everything you put into it in wonderful ways.

What I find even more interesting about this set up is that I never know where I am in the loop, so when I record, I can only really control what notes I play. Where they end up being placed is pretty much up to the machine. This of course excites me, given my interest in generative music and chance opperations.

One of the instruments I fed into this system was a circuit-bent animal keyboard thing. If you slow it down really far, the kids songs it usually plays become unrecognizable and instead it seems to be playing a random sequence of beautiful tones. This already chance based music became even more interesting when randomly edited together by the four track.

After a while the music sort of took on a life of it’s own. I think it came out beautifully, especially for the first try. I can assure you there will be much more of this to come. Especially once I rig up a punch in pedal. Enjoy!

- Star Platform Foothold

Wonders of the cassette tape loop, part 2

December 9, 2006

I was originally planning on going through my tape adventure chronologically, but since I forgot some of my notes at work, I’m going to move ahead in the storyline.

The Cassette Tape Echo

In my quest for a cheap tape echo, i tried innumerable techniques. I added extra playheads to the tape players, I added a playhead inside the tape cassette, Built arms to hold tapeheads and ran tape around them. No matter what, nothing eventful ever really happened.

At some point, I realized that if I had the leads from the additional playheads running back into the tape player, I was esentially recording with 2 heads, instead of recording with one, playing with the other. Then the idea of Frippertronics came to me. I could use 2 tape players. One to play, one to record!

Frippertonics, broke with my original plan, in that it did not appoximate the WEM Copicat. Instead of it making a nice controllable echo, it generated more of a return system. Even though it was not my original idea, I was intrigued by the possibilities, so I started trying to figure out how i could go about assembling a Frippertronics cassette unit.

After some searching I came upon 2 tape recorders that had plastic sides I could cut through so that the tape could run from one player to the other. I then built a loop using 2 cassettes that I also cut open and then joined.

Cassette Frippertronics diagram: (clicky clicky)
Cassette Tape Loop Frippertronics

Robert Fripp and the Frippertronics system:
Frippertronics

As you can imagine this doesn’t exactly work like a charm. However, it was quite charming. The main issue with this settup is the really poor tape tracking. The tape warbles along, jittering and dragging all the time. This is in part due to the fact that only one of the tape reels is moving the tape along.

The ideosyncracies of this setup actually turned out to be quite pleasing. I really liked how whatever you played into it, got re-interpreted by the system on the way out. As I was playing with it, I had the rare forsight to record it. So of course I present it to you here. What you are hearing is an old Yamaha, single oscillator synth played through the cassette loop Frippertronics system. I basically am just improvising mindlessly and listening to the playback. I later added some slap delay and reverb to soften the very square wave sound of the synth, and it actually dresses up quite nicely.

Enjoy!

Cassette Tape Frippertronics

Wonders of the cassette tape loop, part 1

December 5, 2006

I have an odd obsession with tape. I love the way it works, the way it sounds, the way it can be degraded, everything about it.

When I was a freelance designer and had a LOT of time on my hands, I did a lot of experimenting with tape. Almost entirely cassette tape. Why cassette tape you might ask? Cassette tapes and players are cheap, and readily available and if you break anything, you are at worst out a couple of bucks. I have destroyed about a hundred walkmen and other various tape players in the the past few years. If those were reel to reel recorders, I’d be broke by now.

I have built crude mellotron devices, tape theremins, loopers, loop mixers, crude tape delays, etc etc etc. The thing that started it all though, was the simple idea of the cassette tape loop.

In the time before detailed wikipedia articles the idea was just a rough concept that existed pretty much only in my mind and the minds of a few others, who to my shegrin were not very vocal about techniques. I ended up figuring out the Chandler loop (the name of which I just found via the wiki, which I also just found) and improving on it somewhat to get longer loops.

Here are the 3 basic looping techniques for cassettes:

Standard cassette tape loop Chandler cassette tape loop Möbius cassette tape loop

Here is a diagram of a standard Chandler loop: (yes the tape does rub in one spot, hence the modified version below)

chandler loop diagram

And here’s one of my Chandler loop cassettes, modified for longer play:

Modified Chandler cassette loop

Initially, I was inspired by the idea of being able to build a self contained tape echo, a concept that eluded me until earlier this year, and functionally still does. Ideally I wanted to fabricate my own WEM Copicat. Of course, that’s an extremely complicated feat, especially for an electronics novice like myself, but I was obsessed with it, as I knew it was (if only faintly) possible.

So, in the process of breaking way more tape players than I care to admit I began to get more into the loops I was making than my original goal. I would randomly record music (original or otherwise) onto cassettes of various lengths and then play back the loop to see if anything accidentally musical happened. I’d play a few at once at times and improvise on accoustic guitar along with it.

My partner in crime complete with pitch control:

tape player
tape player

Eventually it occured to me to take the erase head off so that i could keep recording layer after layer onto the tape. This by far was one of the most exciting things for me at that time. It was so primitive and damn near uncontrolable, but it made the most amazing “instant music”. Some of the loops ended up actually being quite listenable for a period of a few minutes until you got sick of them.

The sheer nature of the process of recording these kinds of loops forces you to plan and limit yourself. Limits and planning are in my mind, some of the greatest assistances to creativity. You can fit a couple of tracks in before it geats to murky, so you have to record the least prominent thing first and work towards the most prominent. You have to be aware of the tape running so as not to overdub too many times. I recorded tons of stuff this way, most of which got promptly recorded over. It’s so much fun, it’s hard to stop fooling around with one loop, and before you know it, you record something too loud and it kills it.

At some point I got the idea to perform this destructive recording process, where I kept adding to the loop, then recording the result on my computer, then adding and recording again. I edited all of the bits together as one “piece” which is what I offer you today. I hope you enjoy it.

I have more cassette tape loop adventures to cronicle here, which is why this is titled “part 1″, so look for more in the future.

Tape loop collage 1


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