Building an opto compressor from a kit

Discussion in 'Compressors / Limiters (analog)' started by DonnyThompson, Oct 16, 2017.

  1. DonnyThompson

    DonnyThompson Distinguished Member

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    (or anyone else who might be able to help)

    Hi guys :)

    So, lets say I have a little more than just a passing interest in perhaps building an opto compressor from a kit...and I want to start by familiarizing myself with basic electronics knowledge.
    Is there a good textbook I should start with to gain a greater understanding of what it would take to be able to build gear from a kit - similar to what Marco did with his new mic?
    Or does that sort of project require advanced skills?
    I don't mind putting the study time in, and realize that this knowledge won't come come in just a few days, or even weeks...
    Would there be an easier audio kit project - other than a mic or compressor - that I could start out with to get my feet wet? Something that, if I totally screw the pooch on, wouldn't be a "oh God kill me now" kind of price mistake?
    Thoughts?
    Thanks. ;)
     
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  2. Kurt Foster

    Kurt Foster Distinguished Member

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  3. DonnyThompson

    DonnyThompson Distinguished Member

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  4. Boswell

    Boswell Moderator Distinguished Member

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    It's a great idea, Donny, but it does depend fairly crucially on how much soldering experience you have. Modern kits are obliged to use unleaded solder, and this is much more difficult for inexperienced users to make reliable joints with.

    In the past year, I've been asked quietly by two different friends of mine to have a quick look at kits that their teenage sons have assembled but didn't work. In one of them, I could pull component legs straight out of their solder joints due to inadequate heat from the iron.

    My advice would be not to start with an exciting but relatively expensive kit, and instead go for a simple kit first to hone your techniques. I'll have a look round and see if I can come up with any suggestions.
     
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  5. audiokid

    audiokid Chris Staff

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    Warm Audio should make a kit!
     
  6. kmetal

    kmetal Kyle P. Gushue Distinguished Member

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    Are there any books tho? Something that would help a novice better understand what the electronic components do from an audio perspective?

    Like for instance I know a capacitor temporarily holds electrical charge. I still don’t know when you’d use one in an audio circuit or why, and how it affects the audio signal, which is by all accounts a negative one.

    I’ve watched MIT classes on YouTube, a bunch of EE stuff as well, but I haven’t found a good source for what the stuff does in audio terms. There’s plenty of books explaining what the knobs and faders do on mixers and gear, I’ve been empty handed in my search for something like that on a component level.

    Do books like this exist,? Or is it more you just start building and associating the peices/mods to the audio via trial and error?

    I feel like I’m just drowning in the deep end of things. Since I too like Donny have an interest in making some gear, or at least being able to communicate with gear designers on a reasonable level.
     
  7. kmetal

    kmetal Kyle P. Gushue Distinguished Member

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    Lol Neve too!!!
     
  8. dvdhawk

    dvdhawk Well-Known Member

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    Regarding the solder issue, I buy my solder (and solder accesssories) from MCM Electronics (Newark), right there in Ohio. I use 60/40 (60% tin /40% lead), but they also sell up to 40/60 (60% lead). Or it might be era appropriate to go nuts, and get solder that's 18% tin / 2% silver / 80% lead.

    Lead-free solder is a definite PITA.

    Donny, I'm installing a bunch of XLR / SpeakOn floor pockets and (10-pin) XLR wallplates this week - then the mating 10-pin cable ends. Only 95% of which will have to be done sitting on the floor. All the fun of soldering a patchbay without any of the comfort, light, or reasonable flat work surfaces of a proper workbench. It's loads of fun, you're welcome to join in. I'll supply the iron.
     
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  9. pcrecord

    pcrecord Quality recording seeker ! Distinguished Member

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    I do research complete and comprehensive compressor kit from time to time.. but I have yet to find one that seems affordable and hassle free.
    I'd be greatly happy to find one.
    You see I'm good with soldering but I have no electronic knowledge to evaluate and modify circuit. So to me microphone-parts.com was the perfect choice.. their manual are so simple to follow, it makes it easy.
     
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  10. kmetal

    kmetal Kyle P. Gushue Distinguished Member

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    Lmao... “without comfort, light, flat surfaces....”

    What’s the 10 pin connectors for???? just wondering.
     
  11. dvdhawk

    dvdhawk Well-Known Member

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    I'm using shielded (FTP, technically) Cat6a 23AWG for the Audio network connecting the mixer to the rackmount mixer/stagebox. I'm also using the same type of cable for the HDMI video distribution (from 3 different locations). This cable is probably overkill for the audio network, but essential for the video network - given the distances I'm sending the HDMI.

    A) The 10-pin XLR should be more durable and reliable than an Ethercon RJ-45 connector, over time.
    B) A typical RJ-45 network cable is 8-conductor, and the 2 extra pins on the 10-pin XLR will support heavier wire for control voltages (+12V DC) to remotely trigger the power sequencers in the amp racks.
    C) I can gender the Audio cable and the Video cable differently, so they're idiot-resistant. The wallplates will be labelled and color coded, but gendering them opposite will prevent any mistakes.

    The wallplates at each of the 3 locations will also have 5-pin DMX and a standard network connection. I'd much rather solder an XLR than terminate a normal Cat5/6 cable. The 23AWG version is 5x more difficult and time consuming.
     
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  12. Boswell

    Boswell Moderator Distinguished Member

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    I'm posting this rather tongue-in-cheek, but it's an interesting video, and there are some amusing stop-frame sequences near the start. The meat is from about 8 minutes in. @DonnyThompson: some useful info on soldering at the heavier end of the scale.
     
  13. DonnyThompson

    DonnyThompson Distinguished Member

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    LOL. even if they did I'm not confident in my ability at this juncture to turn a kit like that into a very nice boat anchor with a VU meter. Lol.

    Have you checked out the link to the list that Kurt posted above? There seems to be some very cool possibilities there!

    @Boswell I think I may be out of my depth with this whole idea pal. Yikes.
     
  14. Boswell

    Boswell Moderator Distinguished Member

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    No, don't get discouraged! It makes the point that there are techniques to learn as with any craft. The electronic end (small scale) of soldering is mostly straightforward, but it's amazing how many people I have seen do poor work simply because they do not have the right tools for the job.

    The video has a throw-away remark about on-site tool kits usually having a cheap under-powered soldering iron, which is exactly what you do not want if you have a time-constrained task to carry out on heavy-duty connectors. However, the same applies to small-scale home electronic assembly work, and a good-quality temperature-controlled iron is a very worthwhile investment.

    I had a look around at possible starter audio projects, and, out of curiosity, went back to the Hairball site. I have known of their products for several years ever since I gave a helping hand to an acquaintance who had decided to build one of their 500 rack units. I see their Bronze pre-amp kit is around $300, but does need a 500 series rack to house it. If you already have a 500 rack, this would be an interesting starter project, as having the rack removes the safety-critical bit of getting the mains end of things right. I was surprised to see they offer a Hakko temperature-controlled soldering iron as an option!

    Another place to look is Seventh Circle Audio. Their B16 model is a compressor card, but I have no operational experience of it, either at the construction level or as a final product.
     
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  15. pcrecord

    pcrecord Quality recording seeker ! Distinguished Member

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    I did open the link but didn't analyse the options yet.
    The Hairball solution seems complete and interesting but the calibration seems the hardest part to do. Where do I find an harmonic distortion meter I wonder ??
    http://www.hairballaudio.com/blog/resources/build-guides/fetrack-v2-buildbrstep-4-calibration

    The other thing is, the Hairball 1176 kits are 465$ and 595$. When a Warm audio WA76 is 599$ it makes you think twice.
    Where's the fun in that you'll say ! As much as I like DIY, if there's no money to save and with the risks of failing the project, I'm not buying.
    Unless someone can demonstrate how much better the kit sounds vs an all made one.

    Of course, I wouldn't build a classic compressor as my first project.. Start with a DI or a guitar pedal. If you are still confident after that, there's hope you won't screw up a more costly kit ;)
     
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  16. Boswell

    Boswell Moderator Distinguished Member

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    Use of a distortion analyser is a small, optional part of the setup, but I agree that they make it sound more complicated than it actually is. You are not trying to make measurements in this step, only adjusting for minimum harmonics. It can be done using your 24-bit audio interface feeding a DAW with a spectral analysis mode.
     
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  17. dvdhawk

    dvdhawk Well-Known Member

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    If I recall correctly, @Todzilla built a few of the Seventh Circle preamps and was very happy with the results. Maybe he'll chime in next time he stops by.

    Also for clarification, I prefer soldering SpeakOn panel mounts for durability wherever possible, but would not recommend soldering the cable ends for the reasons given in the video. It compromises the insulation, makes the wire inflexible at a critical spot, and makes it much harder to repair.
     
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  18. pcrecord

    pcrecord Quality recording seeker ! Distinguished Member

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    What do you think of the hairball quality vs an already made comp clone ?
    Is it worth it even at the same price ?
     
  19. Kurt Foster

    Kurt Foster Distinguished Member

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    an 1176 and an LA2a are different beasts. you are comparing apples to oranges.
     
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  20. DonnyThompson

    DonnyThompson Distinguished Member

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    Actually he wasn't, Kurt the Warm WA76 is a FET compressor styled after the 1176. I think you saw the "WA" part of the prefix and mistakenly thought he was referring to the WA-2A. Which is Warm Audio's Opto limiter. ;)
     
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