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On a DIY mission!!!

Discussion in 'Pro Audio Equipment' started by Cucco, Jan 23, 2006.

  1. Cucco

    Cucco Distinguished Member

    Okay, I'm sick of being afraid of my soldering iron... :lol:

    Here's what I'm planning to start with.

    I have a ART ProVLA. I kinda like it on a lot of things, but I want better and more! So, here are the first things that I'm gonna attempt.

    1 - replace all potentiometers with detented controls (likely Penny and Giles - both for general overall quality and for availability). I get a woody over detented controls - I wish EVERYONE would detent!

    2 - replace the tubes. I'll probably do this first - maybe even today. I get radically different sound out of the left and right channels. Left is heavily distorted and outputs a non-symmetrical waveform, right looks and sounds fine. I think I'll go for GT Gold series. Yeah, I know there are far better tubes out there, but I've been pleased with other GT Golds in the past - and what they do is test a bunch of tubes and rate them into their Silver, Gold and Regular lines. The consistency from one Gold Series to the next is there.

    3 - replace the power supply. I don't know how much advnantage I'll get out of this with the ART, but I HATE the attached power cord. So, I figure I'll give it a whirl and see if there's a benefit.

    These will be my first steps. If I'm confident from there out, I may get down to the board level and start picking and choosing components to replace. Goodbye chinese capacitors - hello British split-foils!

    We'll see.

    So, I have a few DIY questions.

    1. When DIY'ing cable, I use a torch and a mechanical arm to hold the cable and connectors respectively. I tin the cable leads and then apply solder to the connector. Then, I place the cable on the connector and apply precise heat. So far this has worked FAR better than any attempts I've had at soldering. I use a couple different blow torches for instrument repair for very detailed work, so I'm pretty good with them - as far as getting heat where I want it and how much I want.

    Does anyone know any serious disadvantages to me doing it this way?

    2. Where is a good place to get DIY parts?

    I've got a source on some good P&G faders/potentiometers, but caps and power supplies and so on - a little tough!

    2. b. Who makes good board components (caps, resistors, etc.)?

    I think that's it for now. I'll keep everyone posted. Who knows, maybe I can make a mastering limiter out of this thing yet.

    BTW - the reasons that I'm dissatisfied are:

    1. Inprecise. I can NEVER return the device to the same place twice. Part of this is due to the lack of detents, the other is that ARTs markings are essentially useless. Their thresholds are wrong, their ratios are wrong and their output level indicators are wrong. I hope to correct this with better potentiometers and some paint!

    2. Sound. I genuinely LIKE the sound of the unit when it is the right sound. BUT, I think it could be far more versatile than it is. I just don't understand why a piece with this design should impart SO much color!

    More later........

    J. :D
  2. Kev

    Kev Well-Known Member

    as with all subjects
    Knowledge is everything

    too many questions !

    Soldering - practice makes perfect

    Parts - many many place will have what you want
    very basic answer
    resistors - %1 tollerance metal film
    caps - electros 105 deg types
    other caps MKT is a good filter type
    POTs - very hard to get quality these days

    it would be much easier to take the question one at a time with some specifics to refer to
  3. mdemeyer

    mdemeyer Active Member

    For parts, I like Digikey for a good selection of components:


    Good selection and stock. Doesn't mind small quantity orders.
  4. Cucco

    Cucco Distinguished Member

    Thanks Mike. I'll contact them.

    Okay, so my first evening of tinkering was successful.

    I replaced the tubes with Mullards from GT (12AX7M) and already the unit sounds quite a bit better. Also, the distortion is WAY down.

    Next, I checked the resistance of the attenuators.

    They are marked:

    Threshold - C10K (I measured 4.8K ohms though. It is also hooked to a resistor, but I did not check the value - my color:number memory wasn't good, so I figured I'd check it out later.)

    Ratio - B100K (I measured 74K ohms)

    Output gain - B10K (I didn't get to measure it, my son got cranky).

    I also got a new soldering iron - it's in the form factor of a soldering gun but with the fine tip. 30W. I find it SO much easier to use!!!

    So, here's the next problem - P&G potentiometers come in values of 1,5, and 10K. Could a simple resistor in the path fix this, or is there another solution?

  5. Reggie

    Reggie Well-Known Member

    A torch? That sounds crazy. I would probably kill myself. I don't know a lot about their heating properties, but I would think it wouldn't be able to heat joints as quickly and non-destructively as the soldering iron. And I would personally prefer a pencil iron to a gun, but different strokes.

    I've seen a few other people have similar ideas about the VLA, but few people get farther than changing the tubes and perhaps caps. I don't know but maybe it would need to be basically redesigned to change its character too much from what it is. Everything has its use I guess. You should build a G*S*S*L as a learning guide. and as a kick ass comp. It's too easy.
  6. Cucco

    Cucco Distinguished Member

    You'd be surprised. The torch actually heats the joint very quickly, since it's output is as high as 1200 degrees farenheit. I'm quite used to using it on very precise jobs. Trust me, when I hit my $10,000 french horn with a torch, I'm sure to hit it EXACTLY where I want it and no where else. It takes a bit of practice, but they can be VERY precise.

    Also - the gun I just got is only a gun in form factor, the tip is just like a pencil iron. I just have a far easier time manipulating the gun. Obviously, a regular gun's tip is WAY too broad. Just practicing tonight, I was easily able to unsolder two potentiometers and 4 capacitors and resolder them from a broken POS headphone amp I had laying around.

    I'm hoping to take what is a decent or even usable limiter for "ghetto" mastering and make it a viable mastering tool. I don't doubt that this may be a hell of an effort, but I'm willing to learn and work on this.

    I figure or $300 to start and then maybe $500 or so in mods, if I can make it sound THAT much better, it might be worth it.

    Once I'm done, I might send it over to John Scrip and see what his opinion is. I think he has one unmodded and could give me a good impression as to whether it was worth the money and efforts.

  7. Cucco

    Cucco Distinguished Member

    For potentiometers, I've been looking at all sorts.

    The output needs to be an attenuator and the threshold and the ratio need to be potentiometers, no? Or am I stupid and they all need to be the same thing, just different resistance values?


    PS - God DANG stepped attenuators are expensive. 24 position switches are around $130 and up per piece! That would be $1000 upgrade just for the stepped attenuators! No wonder mastering gear costs so much!
  8. Kev

    Kev Well-Known Member

    if you are really interested in DIY


    ask me for direct links to things hidden at the Factory

    my home site for some interesting DIY links
    The GSSL is a fine compressor ... even in it's standard form

    walk before you try running
  9. therecordingart

    therecordingart Well-Known Member


    The DIY bug will bite you! Be careful! I started building stompboxes then moved on to an SSL based compressor, and I'm now tackling the Pultec, LA2A, and some Neve stuff!

    When I don't need "quality" parts I normally go through http://www.futurlec.com because their prices are fractions of DigiKey and Mouser, but their selection is smaller.

    Good luck on the ART....you can go to Blacklionaudio.com and contact the guy that runs it because I believe he has mods layed out for this unit.
  10. Cucco

    Cucco Distinguished Member

    Thanks Art! You're the bomb!

    I've just been bitten. I started taking apart $*^t last night that wasn't broken, just so I could practice soldering. So far, my USB hard drive enclosre has been field stripped and put back together and to my amazement, still works!! (I didn't get nuts and take chips off, just some caps and some resistors...)

  11. axel

    axel Guest

    kev wrote:

    i am not totally shure if today but it was usually not a problem (at least in europe... the last time i ordered some was about two years ago) to get penny & giles pots 'n' faders, they cost a fortune, but they are simply the best. just the question if it makes sense to stick a few hundred euro / dollar pot into a DIY, to save money (i mean with DIY-ing)

    sorry, just talking a whole lot-a-rubish.
  12. Kev

    Kev Well-Known Member


    you have to pay for the info ??
    this stuff was all discussed at both Tech Talk and now the LAB
    I hope those prices do include the parts.

    just do a search !!
    just two of many at the LAB
  13. Cucco

    Cucco Distinguished Member

    Yep. I just talked to Dale Manquen - the US distributor for P&G. He would have no problem getting me some new pots. But, they only have them in 5K and 10K values. Two of the pots (out of all six) are 100K. I would probably have to go to ALPS for that.

    They are around $160 each!!! ZOINKS. I don't mind dropping the $$ if it's worth it. The fact is, I actually dig the ProVLA as it is, but hear room for considerable improvement. I'm thinking I could really polish this turd into something quite nice if I keep working at it.

    Does anybody have any recommendations for lesser expensive but still high-quality pots. (Given the unit's original price and it's total potential, I'm deciding whether $900 of upgraded pots is really going to make sense...)

  14. Kev

    Kev Well-Known Member

    If you were here I could take you to my local shop and show you and chose a pot for each job

    it's my experience that lets me do that

    you need a pot that fits the physical location
    otherwise you will need to do some metal work
    what hole size do you have ?

    Then there is the shaft size and type and whether you want to re-use the original knob.
    what shaft size and type ?

    Then there is value and type ... say Log 100K
    what value and type ?
    the hardest is the reverse log pots

    JLM have some detented reverse dual log pots in a couple of values and can be set up for a variety of situation.

    take things one at a time and give some specifics
  15. Zilla

    Zilla Active Member

    Torch and soldergun?... forget about it.

    Once you try a quality iron and solder, you will understand why. Making a good solder joint is key to making good electrical connections while avoiding damaging circuit components. Get a Weller WTCPT with an assortment of tips (600, 700, 800 degrees). Silver bareing solder like Wonder Solder is also worth the price.

    Good pots are hard to find. But it is easy to replace them with stepped attenuators. Repeatable and better sonics.

    Quality part sources:

  16. Cucco

    Cucco Distinguished Member

    Thanks Kev.

    I pretty much am taking things one item at a time. Right now, it's the pots. Next, it will be the caps and the opamps. The tubes are already a done deal.

    As for the size, I'm not concerned in the slightest. The chassis has so much room behind the knobs, anything will work. (even the REALLY big ones). Also, the pots can bypass the small daughter circuit board as they are wired (not traced) to the motherboard from there.

    The resistance factor and the tapers are easy. I've already detailed those. The thresh and ratio are linear tapers (standard, not reverse) and the output is log.

    As for knobs, I'm not worried. If I have to, I'll cut new ones - machining ain't a problem.

  17. Cucco

    Cucco Distinguished Member

    Thanks Scott!

    Don't get me wrong - the torch I've only used in the past cuz I'm good with it and only on cable jobs. (And I'm talking a precision torch, not some huge Benzomatic... :wink: )

    The gun is not a traditional gun. It is a true soldering iron with multiple tips. It's just held like a gun. The tip is still the fine point soldering iron type tip.

    I already dropped the cash on the good solder. (Lead free, silver). I have tons of that laying around. I use it for musical instrument repair. Lead solder is a BAD idea when it comes to brass instruments...

    I'll check out the sources.

  18. Kev

    Kev Well-Known Member

    Most of my stuff uses the simple pots I find at Jaycar
    ... even so, I hand pick them based on feel
    I very rarely have to change them
    and some items have been in service for 10 years +

    when I need stereo or recall I'll use a rotart switch
    Lorlins are fine for a start and they have a 1 pole 12 position
    beyong that comes the Elna's

    For minature PCB switches and pots ... Farnell, RS, WES Digikey all have extensive catalogues to choose from.

    I would change the hole or Knob if I didn't have to
    so again
    what holes size, shaft size and type ??
  19. Cucco

    Cucco Distinguished Member

    I really don't mind modding the hole or the knobs (in fact, I'm getting new knobs regardless. The existing ones are plastic. I'll be making milled aluminum or epoxy lacquered bronze ones).

    But the hole is .3" in diameter. Using my trusty micrometer, I got .294 but was able to "stretch" it to .3" In reality, .275" would be a good fit without too much wiggle room (room for dirt) but still enough that I won't have a tough time mounting it.

  20. Kev

    Kev Well-Known Member

    my catalogues are in mm
    for example the Lorlin switches are M9.0 for hole cut out and 6.35 mm(1/4inch I s'pose) for shaft

    I think they come in both flat and round but not splined
    the PCB mount rotary that JLM uses is a splined shaft and so is his pots

    but the pots are very small at 16 mm and have the 41 detents

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