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The Dynaco Tube Audio Forum

Dedicated to the restoration and preservation of all original Dynaco tube audio equipment - Customer support for Tubes4hifi VTA tube amp and preamp kits and all Dynakitparts.com products


4 posters

    changing the color tubes emit

    wedg714
    wedg714


    Posts : 74
    Join date : 2011-11-23

    changing the color tubes emit Empty changing the color tubes emit

    Post by wedg714 Wed Dec 07, 2011 5:40 pm

    i recently saw somewhere a dynaco amp that could change the color that the tubes emitted. does anyone out there know how this is done?
    wedg714
    wedg714


    Posts : 74
    Join date : 2011-11-23

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    Post by wedg714 Wed Dec 07, 2011 6:26 pm

    it was on ebay and it was a st-120 item # 150700540959. someone asked how he did that and he answered "very carefully" would really like to know how to do that . nice effect
    richtp
    richtp


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    Join date : 2011-11-18
    Location : Sterling MI

    changing the color tubes emit Empty Re: changing the color tubes emit

    Post by richtp Wed Dec 07, 2011 9:09 pm

    I think that they use led's to change the tube colors. I know you could mount an led in a 9 pin preamp tube socket. I am not sure about an octal tube with a base though?? I saw a few amps on ebay like that too.
    mantha3
    mantha3


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    Join date : 2010-11-10

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    Post by mantha3 Wed Dec 07, 2011 9:43 pm

    McIntosh is doing an anniversary amp with LEDs under the tubes.. Most people complain that you can't turn the LEDs off. I guess if it were me I'd like to be able to turn the LEDs off.

    I think you can just drill a hole in the center pin of the KT88s and GZ34s to get the light up into the tube. Or angle the LED towards the tube at an angle from behind the tube.

    Def. LEDs for the effect. Just some LEDS, a drill and some high temp silicone to hold in place. It could be a 12 volt walwart power to supply the LEDS or something.. Or some of the tube heater power.

    Gimickey... I dun know. Could be cool to see up in person.

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    Guest
    Guest


    changing the color tubes emit Empty Re: changing the color tubes emit

    Post by Guest Wed Dec 07, 2011 11:37 pm

    It is a cool affect - my c220 has LEDs that you can switch off and on - you need
    to remove the cover to see them though - here is a shot I took with the cover off:


    changing the color tubes emit Co_14811
    Roy Mottram
    Roy Mottram
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    Post by Roy Mottram Thu Dec 08, 2011 2:48 pm

    I've built quite a few preamps with either blue or violet LEDs under the tubes, here's a photo on one on my SP12 preamp
    With an RGB LED you can have an infinite variety of colors and intensitys
    On an octal tube, "very carefully" would be drilling a small hole (very carefully!) into the locator pin

    changing the color tubes emit LED-12
    wedg714
    wedg714


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    Post by wedg714 Thu Dec 08, 2011 3:15 pm

    how do you power the led's?
    Roy Mottram
    Roy Mottram
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    Post by Roy Mottram Thu Dec 08, 2011 8:43 pm

    resistor and filament power
    wedg714
    wedg714


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    Post by wedg714 Fri Dec 09, 2011 7:59 am

    do you have a diagram including resister values?
    wedg714
    wedg714


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    Post by wedg714 Fri Dec 09, 2011 12:34 pm

    the main question i have is: can you tap into the 6.3 volts on pins 2 and 7 of the outputs and pins 4 and 5 on the 6an8 or do you need a seperate filament transformer
    Roy Mottram
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    Post by Roy Mottram Fri Dec 09, 2011 1:42 pm

    same as powering any other LED, most LEDs need about 2v. The resistor value can be anything in a range that will give the LED around 3 to 10 ma of current, so with 6v filaments I'd try a 470 ohm resistor, with 12v filaments a 1K usually works very well, some blue LEDs are too bright, so a larger resistor. Take the voltage right off the tube filaments, can be either AC or DC, doesn't matter, an LED will work with either, but if it's DC then the polarity needs to be correct. LED is connected in series with resistor. It won't hurt to hook it up backwards, it just won't light up.

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