"Dresssing" wiring

Discussion in 'Amp Tech Center' started by seekir, Oct 6, 2014.

  1. seekir

    seekir Tele-Holic

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    I'd never heard the word "dressing" applied to circuit wiring till I got the instructions for the Fromel mod I'm doing on my HRDx. I gather the two power transformer leads should be wound together and all other lead pairs are supposed to be arranged to cross each other at right angles, all of which is supposed to minimize "noise, hum, and oscillation" (caused by EMF?). The Fromel mod instructions are to cut all the wire ties originally installed. I guess no new wire ties are recommended when the amp's reassembled.

    Any opinions/tips?
     
  2. Ed Storer

    Ed Storer Tele-Holic Silver Supporter

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    You have the essence correct. There are more wires that should be twisted; anything with AC (such as heater wiring, power on light) and reverb control.

    The basic rule is to eliminate close parallel runs of power and signal wires.
     
  3. seekir

    seekir Tele-Holic

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    I did some online research, and admit I find the theory of dressing and arranging leads correctly is a bit mysterious. The "heater" moniker for wiring seems to refer to post-power transformer leads, is this correct? The Fromel instructions clearly describe them as the green wires in my HRD which I believe originate from the PT, so I can easily identify them, but I'm curious to know exactly what "heater" refers to.

    If anyone has a photo or link to a photo of good HRD-specific lead dressing I'd sure appreciate seeing it.
     
  4. Wyatt

    Wyatt Tele-Afflicted

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    Vacuum tubes require their cathodes to be heated in order to work.

    All vacuum tubes then have a heater filament wire inside that needs to be powered to provide that heat.

    There is a dedicated "heater" or "filament" secondary on your PT to provide the 6.3VAC needed to power the heaters of the power and preamp tubes. In connects to Pins 2 and 7 for the 6L6GC's and to Pin 9 and Pin 4/5 (connected to each other) on the 12AX7.

    "Lead dress" is about isolating the inference between high current and low current wires and between AC and DC wires.

    To my knowledge all the heater connects to the tubes are on a PCB on the HRD. But the wires form the PT to the PCB should, indeed be Green. As to "good HRD lead dress" I don't see the issue...most of the amp is PCB, the PT wires only run a couple of places and none of them are around the signal path. If there was no hum/noise before, redo them the way they were.
     
  5. seekir

    seekir Tele-Holic

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    Thanks for the clarification on the "heater" term. The Fromel guys evidently disapprove of the stock scheme for arranging and confining the floating leads not printed on the board. The green wires were not twisted together, and numerous other wires that originate from the power and standby switches and the fuse were grouped with wire ties along with the heater lead pair. Their instructions are to cut all these ties and discard them, and dress these pairs according to proper dressing protocols (which am not expert in) when reassembling the amp. I believe you are correct about all the tube connections being printed on the narrow secondary board they are mounted to. "Ribbon" wires connect this PCB to the main PCB. I did not note any extraordinary hum in this amp during the brief periods that it worked properly, but taking steps to minimize noise would seem to be a good plan if rearranging the leads can help.
     
  6. boredguy6060

    boredguy6060 Friend of Leo's

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    The term "lead dress" is a very common term in amp forums.
    Its talked about because its very real, you can cause or eliminate a lot of noise that gets amplified by having certain wires running parrallel and twisting them so that they cross at 90 degrees.
     
  7. muchxs

    muchxs Doctor of Teleocity

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    I was lookin' for a proper Cubist painting as context for this:

    .
     

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  8. FrancoisVillon

    FrancoisVillon Tele-Meister

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    Visual Art Analogue for a MuchXS Princeton Reverb

    OK, consider the bait taken for the remarkable-looking Princeton Reverb clone that is, I hope, destined for a certain NYC client in the near future.

    Picasso's guitar collages are the obvious move but a bit too literal, not to mention too literary, for the job you need done here. You might instead consider more rectilinear artwork like these two Mondrians, a fuzzy one from early on in his career, which is more or less abstracted from a natural object (a tree if I remember correctly):

    [​IMG]

    or, for an even better fit, try on this more recognizable and harder-edged picture, Broadway Boogie Woogie, from later on in his career:

    [​IMG]
    Though somewhat incredible sounding, I'm told Mondrian experts can detect forgeries based upon mathematical proportions favored by the artist and put to use in his painting practice that forgers don't know about.

    Actually, a better bet might be the contemporary artist Peter Halley, about whom I'm no expert--although I've read he's influenced by circuit design and electronics nearly as much as he is by the ways architects structure social space in order to surveil and control human activities. Mondrian, on the other hand, after the fashion of many other early modernists, sought visual correctives to society-wide spiritual turmoil. (Who wouldn't want to completely remake the human sensorium with bold swaths of color?) Here's a recent Halley for your delectation:

    [​IMG]

    Question: Are we amplifier freaks merely taking up Mondrian's project in the auditory dimension? I used to walk out of high volume band practices in a thoroughly altered but pleasing state of mind after bashing out my frustrations through a 100 watt Marshall half stack. Microtonality- and experimental tunings pioneer La Monte Young has taken the concept pretty far in his Well Tuned Piano, performed on a custom-built Bosendorfer. Anyone been to Young and Marian Zazeela's permanent installation The Dream House on Church Street in NYC? It hurts, as you can see from this photo of some folks taken in situ, but I do recommend it. You may, however, find yourself delighted to re-emerge afterward into a city that seems profoundly peaceful.

    [​IMG]
     
    Last edited: Oct 8, 2014
  9. muchxs

    muchxs Doctor of Teleocity

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    The only time nearby Canal Street seemed profoundly peaceful was at 4:30 a.m. back in 1984.

    It might have been during one of those false alarm hurricanes when everyone tapes up their shop windows and gets outta town.
     
  10. Wyatt

    Wyatt Tele-Afflicted

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    The heater wires don't have to be twisted...the idea is that they be kept parallel to one another. We twist them because that keeps them beside one another and always "parallel" to each other, even when curved. Cable ties provide a similar, if less attractive, effect.

    All the wires coming form the PT are AC and "emitter" wires, keeping the heater wires bunch up with them does no harm. I would really have to see the rest of the chassis to note any problem points.

    But the key sensitive wires that have to be isolated form the AC wires are all at the other end of the chassis, most important are the connections to the tube grids, everything introduce before the grid is amplified...and amplified again and again by every tube down stream. The upside to PCB deigns is preamp grids, screens and plates can be routed for minimal interference.

    All I'm trying to say is don't pull you hair out over it.
     
    Last edited: Oct 9, 2014
  11. Petimar

    Petimar Tele-Meister

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    For this old bald guy, this will be a very useful one liner. :D
     
  12. Petimar

    Petimar Tele-Meister

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    That pic MuchXS posted was stunning. I know nothing about wiring in an amp but that is beautiful looking work!
     
  13. Ed Storer

    Ed Storer Tele-Holic Silver Supporter

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  14. seekir

    seekir Tele-Holic

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    I've learned that it's a bit more complex than this. Ed is correct as the Wikipedia site affirms. The winding apparently does stiffen lead pairs, which is believed to minimize vibration/movement of the leads which can add to noise, but the winding also creates opposite polarity in divisions of the wire length. This apparently cancels noise producing EM:
     

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  15. Paul G.

    Paul G. Friend of Leo's

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    Stunning, but obviously a custom rewiring job by a master with a bit of OCD.

    Take a look at this, it's a HiWatt DR103, and this is how they came from the factory. All mil spec, they make incredible clean power, are quiet and pretty much unbreakable.

    P.
     

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  16. ce24

    ce24 Poster Extraordinaire

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    Yep the Mondrian paintings originated from painting of a tree. He then started to pull the background forward thru the gaps in the tree branches then stylized the forms into his cubist style that you see in his later paintings and that evolved into his color blocking we se later on. then this jumped more recently into the fashion world of color blocking for womens fashions. nuthin new in the world.
     
  17. FrancoisVillon

    FrancoisVillon Tele-Meister

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    Yes, the Harry Joyce influence on the Muchxs Princeton Reverb is clear.

    Kind of interesting how many amp builders were ex-military, ex-military contractors, or individuals who learned electronics from folks who had worked with electronics in the service, don't you think?

    Ken Fischer and Randall Smith spring to mind as examples but I know there are others.
     
  18. FrancoisVillon

    FrancoisVillon Tele-Meister

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    Except, perhaps, for works of art by Mondrian, Picasso, or Duchamp before these artists created them?

    As much as I believe--make that know--that there is nothing new under the sun, and as skeptical as I am about the usefulness of art in the world, you have to admit that modern art did its jobs very well.

    Problem is, the project of artistic modernism and the program of social change to which it was usually connected always failed.

    The $10.50 question: Why did modernism always fail?
     
  19. ce24

    ce24 Poster Extraordinaire

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    I really can't imagine someone as seemingly versed as you are in art to be.... "skeptical as I am about the usefulness of art in the world" Art is the history/story of mankind thru the ages. It speaks to the very core of our being. Thinking outside he box is what art teachs us...this is where humankind moves forward. Fun stuff to discuss in a bar....kinda tuff on a chat room...:D

    chers ce24
     
  20. FrancoisVillon

    FrancoisVillon Tele-Meister

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    I think my skepticism is founded in the failure(s) I alluded to in a previous message. Attempts to improve upon the conditions of life-- attempts which modern art and artists were more often than not wedded to--often led to disaster: Constructivist optimism somehow led to totalitarianism in Eastern bloc nations. Realism in modern painting was aligned with failures of late 19th century anarcho-socialist revolutions in France. Other modern art movements operated in Spain, Italy, and Germany alongside well-documented uprisings that failed to stave off fascism or, later on, nip rampant consumerist capitalism in the bud. Then, of course, you had the mollifying and co-opting of Cubism and Abstract Expressionism as representative styles of supposedly "liberal democratic" parts of the planet that are, as everyone knows, oligarchical states operated by a small number of individuals and corporations who deploy immensely concentrated wealth to serve their own interests exclusively. And so on.

    We could get more specific, but then I'll only get more depressed about it.
     
    Last edited: Oct 21, 2014
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