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Planned DIY builds

July 8, 2007 Buddhism 9

Doug Self’s Audio Amplifier Book on Amazon

Hey Martin, hope you had a good week. Here is the link for some of the
stuff I want to eventually DIY
Check out
Neve 1272
Urei 1176
SSL Compressor
Pre 10 48
API pre amp
Tell me what you think?

I noticed the oscilloscope, that I guess is used to see problems in the waveform, which is obviously from electrical dysfunctions. I also noticed that the out put waveform is a lot bigger. Is that due to the pre-amp side of things? Now is this not the same as turning up the volume or does it have more to do with dynamics/headroom of the sound?
It seems that everyone is always seeming to add a transformer to give it a specific sonic colour? Is this correct?
Hope you have a great weekend and maybe we’ll get to enjoy some of those creations
I’ve added a few books that might build on the knowledge for this post – SP


9 Responses

  1. Strangely says:

    Check this post, for links demonstrating the wacky ways to package electronic circuitry!

  2. Strangely says:

    Hi Paul

    I fished around a bit more on the Self site. This page is his base for all the audio stuff he’s written. He’s even got the script and a pic of the box from the Wireless World article I remembered reading! No circuit though, I don’t think. You want to try and familiarise yourself with all his stuff so you can spot the snake oil in other people’s stuff. Nearly everything he’s written is to do with analogue and he tends to accept that if the bits and bitrate are high enough in ADC/DAC’s, then the audio in the digital domain will be perfect. It’s as I say; all the distortion and sound colouration come from the very first point in the chain after the mic element and the final bit of converting electrical energy into sound again (the loudspeaker) (that’s assuming that the internal levels are matched so there’s no clipping, which is horrid). In the analogue domain you have to keep the levels balanced at every point in the chain just the same, but you have to make sure the impedances are right as well. That’s more work in the design and usage processes!

    Snocap etc. That’s a bummer cos I like the look and feel of the snocap setup better than the 7digital. What do you mean about delaying the release date and pre-sales stuff? I can’t see how you do that in the online world.
    I see and agree with what you’re saying about everyone doing it cos it’s easy and everything’s average so it’s harder to get noticed. Actually, I’m not too bothered about that. I just want it out there for people if they decide to look. The performance aspect of it all was the bit I didn’t really like doing, which is why I was drunk all the time I guess. So when I do get round to putting out stuff it’ll probably be all online under my former moniker as there already is an old interest base (having a small track record for the Crawling Chaos name) with new interest popping up from online radio stations etc. I do feel that I have to get all the old stuff out there as a kind of completion to the project which I actually ran away from cos it was killing me at the time. A bit like closure to a bereavemment. I’m trying to make the cause and mission come from complete faith in the Gohonzon. This isn’t blind faith but I feel that I’m making causes with sincerity, and the Gohonzon will keep me in harmony with the universe, giving me protection but not necessarily the outcome I may be expecting…. I think that’s about what I mean, near enough. Probably. Yeah! Right action, right cause! Buddhism is action!

    On that subject. Do you get Sensei’s guidance? If not, these are the instructions:

    If you have a friend(s) who would like to get To My Friends directly get them to send an E-mail to the following address and just simply write – “subscribe”

    from there on it is all automatic!

    Strangely Perfect (Rees)
    Crawling Chaos
    Foetus Products

    All component things in the world are changeable. They are not lasting. Work hard to gain your own salvation. Do your best.

    Nam Myoho Renge Kyo
    Nam Myoho Renge Kyo
    Nam Myoho Renge Kyo

  3. paul says:

    Hey man, unfortunately I work on the weekends so wont be able to make it. I bet its gonna be cool though. As of snocap, Shannon had one of her friends set it up because you have to have a bank account in America. You can however do exactly the same thing through 7digital. You can sign up for free and put up 4 songs of which you can sell. To put up more songs than that you pay something like £70 a year, which is cool because if you sell more than 4000 songs in a week(approx) that is enough to break the top 40 chart. You can delay your release date for a specific week as stock pile pre sales to up your sales for that specific week for more sales. Realistically though, with the advent of anyone being able to release a song unfortunately everyone is. So now the market is totally saturated. You therfore have to have a big fan base and doing consistent gives to even start thinking about moving songs. What do you do, you may ask. Well the best thing is to try and get your music anywhere and everywhere. Shannon is having her songs placed with some independent movies and such. Im entering remixes, doing colaborations and thinking about podcasting my songs and doing some DJ mix mp3s. Anything to just get your skills out there and build a following/buss whatever you call it. The internet has made it easier on one form but way harder on another because now there is so much average stuff out there its harder for your future fans to find you. Its not all bad though, cause the enjoyment is in the music itself and the creation. Hopefully over the next week or two I will have my mobile set-up on the road. It will be a 6in 6out analog plus adat, 2 mic pre-amps with limiter on a laptop and a couple of mics. Plus Ableton and Reaper and oodles of plug-ins. So if you can get a mixer, PA and some space we could have a mess around. See what comes out. Have a think Paul

  4. paul says:

    Hey Martin, checked out Douglas Self. Pretty interesting stuff. He definetely knows what hes talking about. Heres also some more stuff for you too. Let me know what you think
    auroraaudio (link dead)
    Have a good one

  5. Strangely says:

    Hi Paul

    The tape just gives heaps of proper stereo delays with the decay(s) set by the amount of feedback that is re-injected into the mix. You could set it for a very slow runaway condition which was nice when I used it on a dripping tap! (careful nopt to get the mike wet) Very nice build-up. The only trouble was that it used two mixer channels and a buss to itself, so you had to think ahead about what you needed to do. I should imagine that it’s a piece of piss in the digital domain without any tape hiss. However, correct me if I’m wrong as I haven’t got into that in any detail yet. And no, I haven’t got any gear yet apart from me, my brain, a few computers, a acoustic guitar and a simple keyboard. I’m looking at mikes, headphones and soundcard box/interface thingies. There seem to be quite a few ways to do this stuff and I haven’t got money to burn!!

    I’ve just had some excellent news about Holly, one of my former band members and a bit of a hero (he wrote throwing pins, one of my favourite tunes). He’s playing in Blyth on 20th July. Do you want to come? I’m having an idea to pop up for the weekend after the men’s course. His band (him and his missus) are called “The Symptoms”. On MySpace they’ve done a rework of a Crawling Chaos tune called “Trouty Hobin” which he’s called “the punk trout”. Hey! It’s my riff and virtually my sound on the keyboard!! Twat!

    I’ve had extra info and extra links put up from quite popular sites as well which should knock me up the rankings a bit.

    You may be able to help me. I want to get onto the SNOCAP site as it’s looks a professional setup… They only take US addresses at present and no date of when they’re going worldwide. How did you get yours (Shannon’s) set up? Have you any advice on that sort of thing.

    I MUST go to bed now. This is getting ridiculous!


  6. paul says:

    Hey Martin, wow thats cool about the echo. So basically going through the tape acted as a slight pre-delay. Thenn you used the faders of those return channels to add as much or litle of that effect. Thats fucking cool. Ive done something similar with an fx module on an aux and then brought that into another channel and used that aux send level for feedback. But by doing it through the tape you get a warmer sound/echo/reverb. Cool. Do you have any gear at this point? Paul

  7. Strangely says:

    Hi again.

    Just been updating some links…

    I forgot to say that the echo was usually a reel-to-reel tape running
    at 7.5, 15 or 30 inches per second. I did it from a special foldback
    output on my mixer I made, feeding the stereo output from the tape
    into two channels and then re-sending the two outputs back to the tape
    with the left going to right and vice-versa. This would be the signal
    path for anything sent from the echo send (foldback) channel:

    Guitar(say) dry to main steroe mix outs
    Guitar(say) wet to left tape input
    Left tape output to spare mixer channel panned hard left
    Dry direct Output of this fed back to the right tape input as well as
    a tiny bbit of bleed back to itself Right tape output to spare mixer
    channel panned hard right A bit of this sent straight to echo bus
    again as primary positive feedback send.
    These two channels fed into main mix via sliders to get correct balance.

    We used this setup live which I mixed on stage to get it right. When
    we played the electric ballroom the PA guy said we had more wires than
    Genesis (who he’s just done)!!!

    Sometimes I’d stick a speaker in a room and mic up the room sound to
    feed it back into the mix. The key is that I made my own mixer and
    added three outputs to each mixer input channel, two sent to busses by
    potentiometers to adjust volumes and one direct output, post tone
    controls. I really needed more ins, outs, and busses but ran out of
    box “real estate” to put all the hardware. This is the reason why pro
    studio mixers are so big. The electronics is easy; it’s just finding
    somewhere to put all the sockets, knobs and sliders! And deciding how
    to do the buss routing and switching!

    Macabre Royale is a slowed down version of a tune called “Newspapers”,
    heavy on the first snare drum echo (room then a teeny bit of tape)with
    the bass guitar being heavily fast flanged as well. The flanger was a
    bucket brigade device using a state-of-the-art chip, for the time,
    which I stuck in a cheap box made from sheet aluminium. I could
    twiddle all the parameters though. It’s what gives the funny voice on
    Sex Machine amongst other things.

    Skiall was a bit of a jam me and Jeff did. The sound was so good, the
    only thing to add was itself which we did with a stopwatch! We fed
    itself back to the 4 track at full speed on 2 tracks and then at half
    speed so that both versions finished at the same time. It was then a
    question of setting the levels on the four tracks and doing a bit of
    extra EQ.

    Strangely Perfect
    Crawling Chaos
    Foetus Products

    All component things in the world are changeable. They are not
    lasting. Work hard to gain your own salvation. Do your best.

    Nam Myoho Renge Kyo
    Nam Myoho Renge Kyo
    Nam Myoho Renge Kyo

  8. paul says:

    Hey Martin, hope you had a great weekend. Thanks once again for all the great info. Checked out all those links. Still a little bit over my head. Slowly working my way through it all though. Thought Id also start off with, What are volts, ohms etc. Cool, now Im starting to feel a little easier. Now can look at schematic and see, resistor, earth, capacitor. Yeah, rock on. Checked out your site too. Some really cool and interesting stuff. I especially liked Macabre Royale and Skiall. Liked the photos and reference to mushrooms. The soud you got was way cool. It was all recorded to tape, wasnt it? What kind or reverb fx did you use, or did you just mic up the room. Thanks also for the plug in “Recent”. boy-band Paul, that made me laugh.
    So here is my next installment in the quest for all things analogue. I hope you enjoy pre amp 1048 oscilloscope pics
    If you notice, he says it has a very high headroom. Is this to do with signal to noise ratio in
    respect of clarity from low volume to high volume of sound.
    My thoughts being that if you used the top waveform and wanted to raise the overall sound, because the wave is so small(quitest to loudest) if you turned up the gain it would also bring floor noise up. Whereas, on the lower wave, because the wave is so dynamic (there is more distance between the noise floor and loudest peak)you would get a more cleaner sound. Does that make sense? Actually, Im not even sure if it makes sense to me!
    As of 20hz-70khz and not 20hz to 20khz, it has something to do with the fact that even the human ear can only pick up sounds from 20hz-20khz if you eq the sound above 20khz it will have am effect on the sound below 20khz. As far a s I undestand anyway.
    There are 2 men who seem to be the leaders in Audio engineering and they are Ruper Neve with Rupert about 70 designs, including talk of frequencies above 20khz) and Geoff Tanner( who used to design Neve stuff
    back in the 70s
    I think you will find these men of extreme interest. Let me know
    Have a great week. Look forward to our next meeting in cyber world

  9. Strangely says:

    This shows all the op-amp and circuit making stuff I’ve been blabbing about. I checked the chip maker’s site as well. The 1512 is the chip to use , not the 1510. It has just over half the noise of the 1510 at low levels. It’s total amplification is 6db down but that’s nowt as other stages can make that up. The guy gives you everything except the circuit, but with 30mins you could work that out from the board plans, which are good. The inside workings of the chip are interesting. See the maker’s schematic at: You’ll see that the inside of the op-amp (for that’s what it is), contains more op-amps! Like Russian dolls! It also shows you hoe the gain is derived from the ratio of two resistances. That, apart from all the other stuff I mentioned about op-amps, is the beauty! You’ll see that one of the applications for the chip is a “Differential Summing Amplifier”.

    This will be better known to you as….a mixer! See how easy it is? Neve 1272: A six transistor amp! Very hard to get a good frequency response. A much better one, if I recall, was by a guy called “Douglas Self” published in Wireless World, 1976, I think. Yes, here’s some links. All his circuits are in his book.

    This link gives a modern preamp. The page has hover links telling you what the bits do! I think it’s a nice tidy board with sensible description and layout.

    As for the 1272, the circuit is at I can trace the signal path as follows: Single input at U through decoupling capacitor C8 to transistor TR4 connected as common collector output, which goes directly to the input of TR5. This has HF decoupling via the capacitor C2 to stop rf oscillations. TR5 is configured as common emitter follower output through C14 which produces an out-of-phase output at S and as common collector which goes to TR6, another emitter follower producing in phase output at P, thus it gives balanced output across S-P. A lower voltage unbalanced output is at T. The input impedance of the first stage looks like 120k, which seems high so I must be missing something. The next stage is similar with input at L. TR1 is common collector then there is the two-stage Darlington of TR2 & TR3 driving the primary side of the output transformer TX. Negative feedback is by the tap on the potentiometer RV1 through R2 to the base of TR1 which has a lot of HF decoupling to prevent parasitic oscillations through the use of C2, C3 & C5. DC blocking is via C1 & C4 and power line smoothing through the use of C6 & C7. All transistors have bias resistors which I can list as R3,R4,R6,R8,R11,R12,R9,R13,R5,R6 (R5 & R6 also provide fixed negative feedback to TR4), R17,R18(which do the same) * * * * * * * * * * * * This bit just shows how you can go about reading a circuit. It was a bit like my electronics exam in 1975!

    UREI 1176: It’s a compressor gives the circuit diagram. The key component is the FET Q1 which was a BF245A, made by various makers. It’s still being made and costs $0.067 each if you buy a thousand. This’ll be about 10p from a supplier! I reckon total electronic parts would be £15… For a nice box, meter, buttons & switches and transformers (if used). That could be £300 off the top of my head. Nice boxes, knobs and facias cost money. The whole article is at: Another is at BTW, they all mention using a BC107 transistor. Use a BC109C as it has much better gain and noise characteristics. The BC107 is good as a emitter follower driver though. (how do I remember this shit?)

    SSL compressor: is the circuit. As you can see it’s chocker full of op-amps, the TL074 was a quad package one I think and the NE5532 was a twin. The key component is the DBX202 which is a plastic packaged circuit of separate bits. This may be hard to get. It’s a VCA which means voltage controlled amplifier. What other sorts are there? A current controlled amplifier! What’s the difference? They are relating to the key core component on the chip which has all the surrounding circuitry as support. If you look at which shows the internals for the dbx202, you’ll see Q1 is a FET, the U2724E or another, possibly the 2N3187. These are Field Effect Transistors as opposed to the other sort, bipolar transistors. These are the differences… FET: current passing through device is controlled by a “pinch” region produced by a electric field across the device produced by a voltage. This is the gate voltage and it’s thus a voltage controlled device. Bipolar:electrons(current) injected into the base-emitter region of a transistor change the conductivity from the emitter to the collector regions. Thus it’s current controlled device. If you couldn’t get a dbx202, you could always make one on a small circuit board with the diagram shown in the above link. It’s even got BC109C’s in it! It looks like quite a complex project, but not impossible. The bits aren’t expensive, just the boxes and other hardware.

    Pre 10 48: don’t know what you mean! API pre amp:the 212L looks to be a very expensive piece of kit at $695 for one channel. Everything depends on the one monolithic chip. It’s modular so you just slide them in to a standard 19″ rack. The specs at show freq response up to 70kHz with a 0.25db peak at 60kHz. This is totally pointless. The spectral noise chart they show goes from 10Hz to 20kHz, which is standard, so what’s the bit from 20kHz to 70kHz for if you can’t hear it? The chart shows the HF noise to be up to 20db worse than the low to medium range. As you will now know this is Johnson noise and shot noise. What’s it mean? It means that from the graph, if you mike something up and amplify it by 60db, then the cicuit noise is still 45db quieter…which is good. Is it worth it? I don’t think so.

    Oscilloscope: where were you looking at that? The scope is basically a fancy voltmeter. You can use it to show dc volts which appear as straight lines or ac. You stick your probe into where you want and look at the signal. The probe usually has a very high input impedance (originally valves were used at the preamp stage but most scopes use FETs for the input which means an input impedance of many Megohms). You can watch the signal getting amplified by touching various points in the path and then see what happens as you turn things up! Usually you use a sine wave test tone and watch for either clipping or crossover distortion.

    Transformer: these are to match impedances and step voltages up or down. Because they are inductors they affect the frequency response of a circuit. If you want to call this sonic colour then so be it. Input/output waveform sizes: Lets get back to basics… A mike has a very low output. All mikes are little electric generators, just like a nuclear or coal or hydro power station or a car alternator; only smaller. A lot smaller! The reason they have a low output is that the element has to be very small and light to respond to air movements (sound). If it is too heavy, the sound wave won’t be able to push it, so no output. So it’s light which means there isn’t much mass to make electric energy with. We need the electric energy to push our big loudspeaker cones or magnetize our tape (or hard drives nowadays). This takes a lot of electricity; a big PA speaker coil is capable of handling 300W say although only a fraction of a percent is turned into sound energy. Most goes in heating the speaker coil! To get from the low voltage output of a mike to line levels, say, the signal needs amplifying from 0.2 millivolts (open circuit) say to about 1 volt which is 5000 times. To get the voltage for a loudspeaker, we need about 100volts peak to peak, which is another 100 times. The hfe of a single silicon transistor can be from 30 to 300. If we call the hfe 100, hfe roughly equates to the gain, so 5000 amplification can be done with two transistors ie 100 times 100 which is 10,000. Three transistors give a million. So why do all the circuits have heaps of transistors and stuff? Because the gain is not linear across the frequency spectrum. That’s what all the feedback and capacitors etc are for; to flatten the frequency response so that amplification is the same across the desired frequency range. Also, transistors that can handle large values of current (power transistors for the PA) are crap for small signal amplification, and vice-versa. So the scope is showing the amplification. The word “preamp” can be applied to the little preamp box as a whole, or the first transistor stage in the little preamp box (or any amp box in fact!). Dynamics and headroom are different. Dynamic range is the difference between the loudest and quietest sound a system can take. The human ear is a good example. You can hear quiet sounds and the very loudest give you ear pain and eventually partial or full deafness. Electronics is the same be it a single transistor stage or a comlete box of gear. It’s a system. The quietest is just above the background noise and the loudest is when the system is just about to clip the waveform. Once a signal has been amplified to a decent level, the headroom defines the amount that you can go louder before clipping starts. So if you’ve gone up to 1v pp and your amp power supply is 0-30V that means 15V pp, you can amplify the signal another 15-fold which is about 10-12 db. This is the value that you get when you turn a normal bass or treble right up or a slider on a graphic equaliser…. These aren’t by accident you know! It’s made this way because of the limitations, so that’s why the line level is the way it is; it’s a good compromise. Hope this helps. Keep at it. It’s all a best fit for the job really. From my point-of-view, once I’d got the sound pre-amped up, I’d keep it all in the computer. All the compressors and stuff can be modelled really well now, and are getting better and cheaper all the time.

    Strangely Perfect
    Crawling Chaos
    Foetus Products

    All component things in the world are changeable. They are not lasting. Work hard to gain your own salvation. Do your best.

    Nam Myoho Renge Kyo
    Nam Myoho Renge Kyo
    Nam Myoho Renge Kyo

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