Month: December 2009

All amps at the mo’. Read up a little on the TDA2003 and realised the one I’d made was sorted to amplify at 10x but others were using them at 100x so I changed a resistor, divided by ten, and it’s doing everything as it should.

But this small interval between having it not really work to having it work had me designing another one but using a tube… actually I think I wrote about this yesterday… but suffice to say I designed up an amp then went out and found nearly all of the parts I’d need, measured a speaker and found some wood for the box then cut out some aluminium for the electronics to sit in. My plan was to try and make the amp from scratch in one day… but I didn’t make it but I did get this far.

Oops, left the camera plugged into the PC so the batteries have drained again and need charging and it never came with a power supply to run it on 3V. (later on…)

So it’s two stages of tube amplification which is the same as any fender amp from the Golden era then into a j-fet set up as source follower to drive big muff style tone stack, which I suppose I should allow to be bypassed by a switch, then into the TDA2003 at 100x amplification.

I was going to do one of those step by step things, photo essays, pic of the parts, the sheet of aluminium and the plank of wood for the box, the alloy cut and marked, then drilled filed and folded but the camera was on charge… well the batteries (as they are now), so I did it all to the stage of folding up the enclosure and mounting all the hardware.

Today I’m going to make up a small jig of sorts to wire up all the pots to the tag trip and tube base simply because once the chassis is folded it’s really hard to get the stuff soldered up in situ.

The plank is a bit of something or other, an exotic softwood grown here that I picked up in Patamahoe years and years ago and still have enough to make a box and sides. Almost blood red is the wood, so yummy, The speaker is a 12″ alnico magneted Plessey NOS with paper cone and ribs which I also got years ago from a guy in Christchurch. I bought a whole bunch of them for about 10 bucks each and put four in a quad box. Those four sound the best and feature the ribs only around the middle circumference of the speaker cone. The ones I have left, theres three, are either completely without ribs or have ribs all across the cone face. I’ll dig out the other two and use which ever I only have one of for this amp and save the other two for a duo tub at some stage.

I think also that I’ll do a line out on this amp and have a 9V out for fx. The line out will come in handy if I want to do a psuedo stereo thing and maybe send mono signal to this amp then maybe a tremolo into another one.

Always more ideas! Even this morning I thought about doing something with speakers along the lines of the last one in the barbecue tub, the 15″, simply because when I picked it up to move out of the way to photograph the amp chassis, I placed the big speaker tub on top of a frying pan lid and immediately thought that I could suspend a smaller speaker in that… my brain then goes off into the ramifications of crossovers, active or passive?, and how neat it would be to have a whole bunch of different sized speakers suspended in various containers and the whole bunch sitting in a sprung frame so the speakers could flop and jiggle with the sound it emits.

Some chap asked a question about multiple speakers a month or two ago on DIYstompboxes and the consensus was that many the same in series parallel combinations, so it stayed at 8 ohms or whatever, was entirely feasible as long as the wires to the speakers weren’t too long and inductive capacitance became an issue… or was it reactive capacitance. Something beyond my ability anyways that simply means long cables need more power to drive and suffer treble loss which is why systems in buildings, intercoms etc, sound tinny and obscure beyond the cheapness of the speakers… even though they ride the signal on a 50VDC carrier.

I’ve already got unfinished stuff in the pipeline that I’m losing interest in as well as a few projects almost completed that I have almost completely lost interest in and I’m now I’m thinking of a radio tower of speakers in sprung shells. Ideas are always fun to play with and often bringing them to reality and the trouble is often brings can be even more fun!
It would be far sounder physically (sounder as in mechanically sound and physically in regard to physics) to suspend the speakers as I have with wire in the openish enclosures but to then add springs, one or two from above and one behind, from the enclosure to the frame.

It’s kinda is making more sense to me because I’ve got absolutely loads of interesting speakers and an active crossover I made a few years ago that was going to be part of a monitoring system for some PC recording.

One more big bit of furniture to store somewhere though but I do have to work up some significantly aesthetically pleasing pieces that bridge the gaps between furniture making, sound sculpture and plain old art to get photos to send to the Pollock Krasner Trust over in NY next year so maybe this is the thing to do?

Then on the back of it I could suspend a reverb plate, ala Felix the incomparable, so the reverse thrust of the speakers, through the ports on the rear, is picked up and fed back into the system… Shit Bro, I want One!

Yesterdays little play with the TDA2003 amp had me trying different speakers on the end of it simply because at such low wattage output the sensitivity of the speaker is all important. Being the enclosure was quite limiting I couldn’t use the 12″ which actually sounded the best and had to make do with a 5″ vifa I had set aside for an eventual set of monitors.

But I’m now warmed up and upon visiting DIYstompboxes I came accross a thread on sticking a 12AX7 tube before the amp and this isn’t a bad idea as theres an old trick where you can use two power transformers back to back to get the power requirements you need to power a tube with both 12V for the filaments and anywhere over 250VDC for the plates.

The first transformer is set up normally. 240 in and 12 out and you run the filaments for the tube on that. Also you’d throw in a diode bridge and get 12-15VDC off that to drive the TDA2003. Then you grab another 240/12 transformer and throw the 12V you already have into the 12V winding of the next transformer and it gets brought back up to the 240VAC on the other end. This is bridge rectified and smoothed with 400V caps because 240VAC rms becomes about 340VDC. This is more than enough to drive the plates on a 12AX7 tube and it may be prudent to knock it down a bit as the max plate voltage for a 12AX7 is something like 300VDC.
Going into 15-18V windings, instead of 12 will cut it down a bit as it’s the ratios that count here and a 240/12 has a ratio of 20/1 whereas a 240/15 has a ratio of 16/1. 12 x 16 = 192, 192 x 1.414 = 270 and thats a bit closer to be suitable for the plates of a 12AX7 tube.

The 1.414 is about changing rms to a peak value as rms means root mean square and is the AC waveform averaged out but because we are charging caps after a set of diodes then those caps will charge to the peak voltage available in the AC waveform.

Incidentally for those of you that might not know. We measure the wall voltage here as 240VAC and what that means is that we have both positive and negative sides to the waveform and the 240 means that we have peaks running from 240 x 1.414 which is 340 to the peaks so when one is zapped the waveform going into your body goes from 340 positive to 340 negative which adds up to 680VAC +/- accross the complete waveform. So the next time someone says that 240V zaps are quite a shock you can say it was actually closer to 700 that nearly found the heart muscle.

Next thing you do is measure your resistance from hand to hand or from hand to foot and you’ll be able to ascertain how much current you’ll actually have passing through your body at the speed of light. My resistance from hand to hand is about 2 megs so 700 / 2,000,000 = .00035 which is just about half one thousandth of an amp. No wonder they just surprise me. The lower your resistance the higher the current will be and this is why some people get terribly deadly shocks while others merely go “f#ck!” ( a few other things count like perspiration etc, and that counts alot as the salty water is quite a good conductor and so much of the current travels through the perspiration of a sweated person, paths of least resistance and all that.)

But back to amps and I’m going outside to build a little amp using a glass bottle (containing thoriated tungsten), some iron and copper and the odd bit of doped silicon. Hopefully it’ll be louder than all my recent attempts… which still aren’t loud enough to cut above the noise floor at Handmade.

I’ve always found that at this time of year I’m affected by the general malaise that seems to be part of the christmas season. I kinda figured it out years ago after wondering why I would suddenly lose interest as the holidays started and by watching for effects I eventually put it down to the nature of the overlying consciousness at work on all of us.

When the society is out working I can work… but when they decide to do nothing and are thinking of rest (which I incidentally think they think harder about than anything) then all the available creative space seems to be gone and so I just veg until they all get back to work.

This was illustrated last night when a TV star was interviewed about what she was doing for her holidays and after saying several times that she was just going to chill completely for the whole two weeks she then proceeded to explain all the trains, planes and automobiles she’d arranged to be using as she shuffled between three chill out zones.

I’m sorry but I just don’t get that at all. Well I do but I think it’s silly to think one is chilling out while travelling back and forth across the country almost without rest with brief intervals between to acclimatise and before one even gets their bearings and a sense of where they are to be zooming off to some other relaxing place. The sum result being I basically do as little as possible and just let the population at large get it out of their systems.

But we are here for music and related and on that front I did the thing at Handmade last week, the 23rd, and it was yet another working it out kinda gig but it did go rather better than the first one and we ended up almost getting chucked out. My friend Doug joined me and I learned yet again, or remembered, that there is a time and a place for letting those unskilled about the nuances of music making… almost free rein on ones setup. Then Tom turned up, sorry I don’t know his last name, and listened for a while then took over when Doug and I went for coffee down the front.

Whatever huh, but on the promotional side (which is a little scary) I’ll be doing a interview and a little instrument tinkering on Bfm this coming sunday morning. I’m unsure of the exact time right now but it’ll be sometime between 9 and midday on the 3rd.
I love the idea of new experiences, my last little radio interview on said station was way back in the middle of the last decade, but I’m somewhat averse to letting the public know they are going on. I prefer the concept that people are in the right place at the right time which is why I often do things unannounced… even visits accross town. That said I’ll be plugging the Handmade thing, Vitamin S and DIYstompboxes and maybe even this blog.

Back to the Handmade and it’s aftermath. Tom, Doug and myself were down at the car loading the stuff in and discussing the relative merits of the place and the what of its when one of Toms friends arrived in the vicinity and Tom said they were going to be jamming at the Wine Cellar. I dropped Doug off at his studio, can’t call it a house as it’s completely filled up with paintings, offered him my place if I go overseas, and then returned to Town to catch some of Tom and said friend. Tom was on electric guitar and friend was on double bass and they then did some blues. Kinda Cajun blues and I was reunited with the concept of playing guitars normally and the major scale of A. It was great! Both Honkin’ and Tonkin’ were in attendance. I went home and picked up the guitar and realised they’d bin playing in one of my favourite scales.. A major!

But I have done a little work. Below is something I threw together and after finishing I realised it wasn’t what I wanted. It does what I want but the aesthetic is not what I realised I wanted. I’m also quite happy to admit I do actually suffer from that which I sometimes accuse others that being I don’t actually know what I want until I see whats made.

This is the moonlight amp with a speaker, the power supply for the fx, and a container for leads and fx… on wheels.

My unresearched idea for a combo amp. Unresearched because I just let it build itself and because of that it’s far more like a furniture piece than a usable, efficient musical instrument… far too carnivally. But I’m not adverse to the concept but I’ll bin this, as an instrument, and start again I think.

This though is far closer to having something that’ll do the job, pack away nicely yet still retains the ideas of art that appeal to me.

And down there at the back, with all the little holes around it, is the actual amplifier.

Bottom right is the power supply which is 18VDC at a little under two amps so it should be enough to give me about 10 watts.

The above is a ten watter using valves so one can see the obvious advantages of using silicon for amplification. The amp chip is a TDA2003, which costs about 5 bucks from RS, and I’m hoping that attaching it directly to the pot will be enough heat sinking for it. The idea being that the holes drilled increase the surface area around the chip, just like a regular heatsink has fins, while also allowing the required scarcity of metal to allow the lowish frequency of molecular vibration that is heat to be able to dissipate. Solid state amps require big power supplies and big heatsinks because to do what you want them to they are actually very wasteful of power. Anywhere from 50 to 75% of the power needed is wasted as heat. So for ten watts of output one needs at least 20 watts of input power and this is why the power supplies, and heatsinks, are so big on SS amps.

So there you go and because of the radio show being moved from Wednesday night to Sunday morning, and lots of peple back at work, I’ve a few ideas up my sleeve about new things I can build that’ll, as usual, go out into the world untested, usually mostly untried, and “try” to make them work!

Tube, or Valve amps, don’t suffer such in adequacies… they suffer other ones. The parts are big and often heavy and use alot of real estate and are expensive, relatively… but they often sound better and tend to last a long time.

Last night we had the end of year bash for vitamin S and it was kinda equal amounts frustration and fun, not at all because I took along an old friends sixteen year old son who aspires to be a drummer, but thats beside the point because at the end Ivan told me there was a monitor in the bin. Well two monitors but only one was working. So this morning I was dropping the young lad at his Dads workplace, but he hadn’t arrived at 6.45 when we got there, so off we went into town to troll through a bin. The bin was full but I’d been told where it was so it was actually really easy to get out. Man it was a really badly packed bin and shame on the people there for such inefficient use of resources… even if they are chucking them out.

Took it home and plugged a mic in and powered it up and it went but not well. Took it apart and popped the hidden switch from line to mic and found a 4 Ohm piezo tweeter on the bench then carved it up to fit. The one in there was an 8 Ohm magnet and winding type and was mounted like the guy was a farmer and using tools from the landrover. Actually it wasn’t too bad but one needs an incredibly long phillips head screwdriver to get the back off and the tweeter replacing had been done without taking the back off and so what could have been quite a nice job wasn’t so good… and the tweeter was the wrong impedance anyways. So I chucked some foam in there, should have found some dacron but was too lazy, and put it together and it was suddenly much, much better. Looked it up on the net and this stuff, active speakers, have all sorts of circuit protection and other stuff but they’re basically just a couple amplifier chips on a heatsink with two speakers…thank God for car stereos and the surfeit of low voltage chips for their use. The most expensive bit on it though would be the power supply and the toroidal transformer… even more expensive than the speaker. I’m tempted to keep it but it’s ugly as sin, like an unfit fat girl in stretchy lycra, so I think I’ll just flick it off to the highest bidder on trade me… though maybe I should take it and see if Ivan the Terrible wants it.

Ivan impressed me the other day by playing a sink… a stainless kitchen one with two springs bolted accross it… beautiful sounds it made too!

To the side of the monster in smooth black injection (ABS) molded plastic is a 15″ jensen picked up years ago at cash coverters and mounted in a barbecue body. I was going to put it on stands but on trying it out as it is, and having some holes in the back, it’s really easy to move it about and get lots of different feedback tones. I’ve gotten four different notes so far and it’s quite easy to play them. I originally planned to use springs but the ones I had weren’t strong enough, as I was going to mount the front face vertically, and it sagged so I replaced them with taunt welding wire but seeing that I’m using it horizontal maybe I’ll go back to the springs as they were fine in that orientation and I’m kinda wondering what it’d sound like with the speaker bouncing up and down.

So I used it last night and my little moonlight just doesn’t cut it and I think it’s time to get the big amp out of hiding. I built a tube amp years ago with lotsa 12AX7’s and 6V6 or 6L6 output valves in push pull but I’ve never fired it up. The case didn’t come out like I wanted and I needed some switches to fire the different channels so into the waiting list option it went. So maybe it’s time to get 15 watts of tube power into my arsenal. What I’m kind of afraid of is that’ll lead into needing to haul around the quad with 4 x 12 but that’d just be silly having to load the car up with that lot every monday just to get the sounds I end up getting used to… what I really need is to build a champ type single ended amp with minimal parts and about 5 watts of power and use my one great 12″ alnico magnet’d ribbed paper cone speaker.

Oh my God, this amp is packed with features and thats gonna be the case at the end of my three year obsession learning how to do it. It’s kind of a super hot rodded fender of the soldano, mesa boogie variety. Black plate unmatched Jan 6V6’s that can be switched btween fixed and cathode bias, switchable Negative feedback or none and then two channels with separate tone and volumes and an effects loop and a balanced/ unbalanced line out off the speaker output. Thats just from memory so I think theres actually more going on but I just can’t remember.

I had it sorted to switch channels using relays so I could footswitch on the fly but my dreams of being a stage centre shreiking solo guitar hero are long gone so I think I’ll change it round to normal everyday switches on the front and rewire the little relay power transformer as a 9V DC out for FX. I look at this and it’s like about 400 -500 bucks worth of parts and maybe 60-100 hours of assembly and design but I suppose a hand wired boutique amp is worth many thousands of dollars, if it does what its supposed to do, and hopefully this will.

So the Vogue badge goes on a aluminium grill and I should get my brother to Tiger skin some bark tan leather and upholster it and then do some beaten copper corner pieces with little bronze or brass screws. Talk about doing Rich on a budget!

Then the reason all of this has even come about is that I had two other people playing my stuff last monday, after I’d had a go, and realised the speaker on the floor wasn’t cutting through so I planned to build a stand for the speaker so it was off the ground at least 600mm and while I was at it I was going to mount the moonlight amp below it because I’ve never gotten around to putting it in a case and I bent one of the valves pins a week or two ago because everythings exposed on the top… so I thought it would be a good idea to bolt it up into a framework of a speaker stand. While I was going over these ideas and how to do it all I got to thinking of, firstly, cutting away most of the body of the amp so the wiring underneath was exposed while also cutting great big holes in what was left to make it even more interesting looking and from there realising the flatness and squareness of it all wasn’t really to my liking so I went to the idea of taking a piece of aluminium sheet and biffing the hell out of it to make a body more in line with the organic forms I use in my welding.

I know it’s bad form, as the aluminium (or steel, copper silver etc) body on all electronics is so for the reason of being a condusive earth plane while also being a cage of sorts to stop the internals acting like antenna to other signals in the ether, but I’d love to do a tube amp almost inside out where the low impedance circuit could be a tracery of jewels strung around the glass bottles and in a hand beaten body that uses a combination of metals, bloody dangerous of course because we’re talking at least 250 Volts DC (hmm, maybe a safety cage around it all) … maybe if I get some money from overseas (Pollock Krasner trust)… or maybe I’ll just fuckin’ do it anyways!

My new saying… If you can’t beat ’em… get weirder!

This is what I think I’ll be working with for a while or untill some cash comes on-line and I can get to a bunch of unfinished projects can be finished.

The instrument has two bass strings and two piezo’s with preamps and tends to be sensitive enough to be able to play just about everything on it. Yesterday I was going to cut some notches in the wood of the body of it to also have a guiro to play, I’ll get around to it by wednesday and 10 acre block though.
From the piezo’s I go into a phaser pedal and that works really well with the long notes I can get but is somewhat problematic with the resonance setting the feedback note and it’s frequency… I think anyways. Then it’s into the Boss DD-7 which is a miraculous delay pedal I’m just starting to get my head around. Just setting and forgetting doesn’t work with this as the repeats being the same speed gets kinda monotonous but working the speed and feedback and turning the pedal on and off to work over the tails is lotsa fun.

Then it’s into the looper, Boss RC-2, but it’s not used so much as I’ve yet to really understand the possibilities of it but I’m making a little headway.

Last night, after I did a set, Ivan had a go with the setup and I realised how important it is to work the settings on the delay, but he seemed to be having fun… until Karen pushed him off and she started playing it. She seemed to be having fun but was a little too tentative and mystified by the available sounds… but it was interesting watching her.

Next step is mounting the speaker above and away from my hearing. I kinda listen to Rohans advice about speaker placement and stuff but it doesn’t work for me as I need to have the music going out louder than what I require for monitoring so when I place myself between the speker and the outside world… they can’t hear me!

Oh and the mischevious little box with glass tubes on top is the moonlight designed by Simcha Delft of NZ Musician and even features one of his handwound output transformers. Lovely little amp!

I went along last night and eventually set up the equipment I’d taken up the back of Handmade. I had waited till 8.30 in the hope that some others or elses would turn up but nobody with stuff musical ended up in the vicinity.
I was so worried about that but should be over it as it’s happened lots of times before regarding my art. I suppose I’m not the aquaintance type and just have a few close friends so I haven’t got that network of musical buddies to call on. That said, which is a little too self depracating, I didn’t really do much to advertise the show… well almost nothing and my little talk to the Vitamin S crew on monday wasn’t very long on info and quite short on charm I suppose.
So I’m over it and learned quite alot about the space though I could have learned more and will go next time with an attitude adjustment.

The space is like a highpass filter that works really weirdly. It’s hard to get any volume at the end of the long hall I set up in yet the highs and the mids can be heard down the front even with music playing on the internal system. So the noise floor is quite high to start with and then once you get a bit of volume and a certain amount of balance then the highs and mids are thrown down the room while the bass bounces around where your playing.
I only had my small amp, which was made originally to test fx at home without lots of setup and big amps, which would hardly be a single watt of power and it just couldn’t cut through the ambient noise.

So it’s a very problematic place and I’ll go back next time with a bigger amp and a better mixer.

But the guy who was working there, doing burgers and coffee, was really encouraging and said I really should keep it up as the sounds he was able to hear were interesting and intriguing and that it was worth following up on for a month or two just to see what happens. I suppose I agree and will go with that attitude adjustement and live by the name of the thing.

I had the Boss looper so I could build up a host of repeating sounds to jam over and I think I’ll carry on with that particular notion.

Next Wednesday is the 10 acre block workshop at Vitamin S which rules out the 16th and I’ve got an idea that the 23rd will be a totally spazed out chrissy shopping frenzy but I think the 30th will be the next installment.
I’ll redo the flyer with a mind to starting yet another blog, No Rules… except to listen, and then take it from there… actually maybe the 23rd would be good?
Now we go here, the No Rules Blog

I found a site the other day and it’s a wonderful mixture of circuit bending and stand alone DIY electronc stuff.
Named after the friendly ghost
I was led to it by a drone box link I found somewheres and when I found the schematic I was intially perturbed by the apparent complexity but upon further examination and drawing it out in a slightly more comprehensive manner it’s not actually too hard to understand.
If dull electronics observations and circuit analysis aren’t your thing then go here
but if you don’t mind that kinda stuff then open this
It looks complicated but once you break it down to discrete blocks it’s actually quite simple and fun filled.

One section of a 40106 hex inverter (remember the simple synth by Tim Escobedo?) acts as a master clock then this is fed into 4 sections of 555 timers (a 556 is just two 555’s in one package) so you get 4 lfo signals. The 10k’s to transistors and diodes hanging off various junctions are the indicators and don’t need to be there if you don’t want gizillions of flashing LED’s. Then theres a switch at the end to invert ot otherwise the LFO output and another switch to turn the lfo signal on and off. At this point the rest of the 40106 sections come in as the drone signals so each oscillator has it’s own LFO which can have the LFO inverted or otherwise and on or off. These signals are the mixed with an incoming signal and go into a summing amp with a low pass filter tacked onto it.

Pretty straight forward stuff really and quite simple for what can be acheived. I think what I’d add myself would be a momentary switch on the output of each oscillator to ground the signal and with the 4 it’d be quite playable as a stutter effect.

Then we go into a distortion module which is basically a fuzz face circut that has a mixer built around it which also looks kind of complicated but once drawn out with a bit of space around it it’s quite simple.

Last in line is a parallel set of band pass filters that can also be mixed into the signal and from there it goes to a volume then out.

I’d have to say that this is very elegant way to acheive alot in a very small space and you’d almost need 4 classic analog synths with some keys taped down and four sets of hands to acheive the same thing.

Notice also that the Master clock output has a bunch of outputs called in, out and thru. At this point you can modulate the clock signal with whatever… could even have a mic input?
This is the designers page on what goes on with all the controls
And theres even a forum for builders!
Good Golly… don’t you just love the internet?

Here we go… I set a date, the 9th of December 2209, as the starting and then had to do the drawing… so here it is.

My idea is to just have people arrive, with instruments and various noise makers, and then make it up as we go along. Simple as that. I’m kinda thinking that it’s be interesting for the musicians to disperse accross the room, in small groups or alone, and have any audience, therefore, also dispersed. This may work or it may not but it’ll remove visual cues anyways and leave everybody alot more reliant on using the ears.

As for the picture, it’s directly cut from the first issue of the comic “The Umbrella Academy” and is of a small girl leaning against the window of an airship and looking down on Paris and seeing her fellow “students” embroiled in a disaster while there erstwhile teacher stands resolute behind her. But away from the comic the little scene offers a much more sinister range of possibilities… but it’s strong as a composition for black and white and so I’ll keep it. For me it’s kinda like the standoff between paternal authority and feminine creativity and I kinda think that ones initial meeting of the noise and music thing can be the same as ones feelings around the pre supposing about what the graphic means.

So turn up about 8pm on the 9th and we’ll take it from there.

Two power points upstairs and I’ll get some extension cords and multi boxes.