Micro amp collection

Discussion in 'Shock Brother's DIY Amps' started by BluesBlooded, Nov 21, 2016.

  1. BluesBlooded

    BluesBlooded Friend of Leo's

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    Tons of fun. I have a LP and a couple of pedals in the middle of production begging me to return to them and I just can't. This amp thing is so much fun:D

    Turning the components 180 degree was exactly what I was going for. I'm giving also the new chassis more room so I do not have components stuck underneath the board That was a collosal pain .

    I will recheck. I've moved then so often I lost count.

    From PT to Central Tap to V2 - V1 - Lamp. This is the shortest possible route.

    Almost:)

    I will also try to move the OT around to see if it stops the hum. If I can only figure out how to plug the headphones for the headphone trick everyon is talking about. Still searching.

    I'm still commited to do the new chassis even if I can tame down the hum because I want to properly acknowledge Rob's design and I have another idea for the labeling I want to try on the aluminum. I even ordered new caps to do the board. This way I will be able to play this current one until I'm ready to transplant the trannys.
     
  2. D'tar

    D'tar Friend of Leo's

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    I like shortest route for the most part but something like this would be an exception IMHO. The current needed to feed the lamp would have to travel across v1. V1 as stated needs to be the quietest it possibly can therefore a longer run of heater wires hugging the chassis leaving v1 at the end of the heater circuit may give better results.
     
    Last edited: Jan 31, 2017
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  3. BluesBlooded

    BluesBlooded Friend of Leo's

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    There's nothing like trying.

    I'll do some test tonight
     
  4. D'tar

    D'tar Friend of Leo's

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    Just for informational purposes, this is all I could come up with on the headphone test. Any one have more to add or comments on this procedure. Maybe Rob could add something like this to his page. And as we have found out maybe a little more clear explanation of first time start up procedures.:)



    From The Gear Page;


    "First set up the power transformer. If it's not installed yet, all the better, but if it is, this will still help. If the PT is not installed, wire up the primaries to a power cord, but do not wire up any secondaries-- tape the ends of the secondaries. If the PT is installed, fine, just make sure there is no circuit on any of the secondary leads (pull all tubes, and disconnect leads and tape them as necessary).

    Now set up the signal transformer (output, reverb, whatever). Hook one set of OT secondaries (your choice, but I usually go from ground to the highest impedance tap, don't worry about impedance matching here!) to a set of headphones. Tape the primary leads.

    Put the headphones on, plug in the power cord, and start moving the signal transformer around. Try it all over the chassis, and also rotate it. While you might expect the least hum with the transformers as far from each other as possible and at right angles (and that may be the case for you), it might come at an odd angle and/or position. Sometimes the least hum occurs when the transformers are side by side. When you find the quietest spot, use a permanent marker to mark where the mounting holes should be."


    Ken Moon, Jun 14, 2010
    Ken Moon, Jun 14, 2010
     
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  5. brogh

    brogh Assistant Admin Staff Member

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    wow, I catched in late on this thread, BluesBlooded this is spectacular ! great work, i like your designs.

    Well Done !
     
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  6. BluesBlooded

    BluesBlooded Friend of Leo's

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    Rewired the whole shebang. To make sure I don't mix the v2 4-5pin to v1 4-5pin, I used two different color wire.

    [​IMG]

    Move them away from the signal as possible.

    [​IMG]

    And tested. Well let me tell you that my hopes were high and they were terribaly crushed. The same level of noise. But it was worth the try.

    I then proceeded to tape the AC wire as suggested by Andrew.

    [​IMG]

    And yet again, the same level of hum. Not much more to try for now.



    Thanks for the research D.

    So basically, I could try this with my trannys on a table before even trying to design a chassis right? Neither one of them need a load of some sort?

    Well thank you Bro!
     
  7. BluesBlooded

    BluesBlooded Friend of Leo's

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    Could it be that my center tap is not working?

    [​IMG]

    It is right out of the OT and the black is connected to one screw on the chassis.
     
  8. D'tar

    D'tar Friend of Leo's

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    That would be my understanding. hopefully someone that has done it would chime in.

    Honestly, ive never disconnected a center tap to experience the difference. I did have a bfdr clone on the bench with 2 burnt 100r artificial tap completely crumbled into pieces and the amp was as quiet as anything. installing new r did not seem to affect noise level at all.

    Rob mentioned his hum was the pilot lamp too close to v1 or the input jack. have you tried removing it to a different location outside the box temporarily.

    Also realize everything you do could affect everything you have already tried. revisiting your trials with each change can produce new results.

    Im rooting for you here!
     
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  9. awasson

    awasson Poster Extraordinaire

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    Also.... something @D'tar copied from the gear page that I forgot to mention earlier. Power trans and output trans should be at right angles to each other so that their windings are not parallel to each other. If they are parallel, they will I induct with one another but with the windings at 90 degrees they will have less interference with one another.
     
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  10. Average_Joe

    Average_Joe Tele-Meister

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    I have a ham radio model Yaesu 817 that needs the incoming power wires wrapped around a toroid to mitigate the A/C power supply noises.

    Similar to this :
    [​IMG]

    and while playing radio I have discovered how noisy the cheap Chinese wall warts for other devices can be, our modern existence is awash with interference.
     
    Last edited: Feb 1, 2017
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  11. BluesBlooded

    BluesBlooded Friend of Leo's

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    After moving things around a bit, I think I've settled for this design


    V1 is farther from the PT

    Light and power switch are away from input
    [​IMG]

    Power line and fuse close to PT and far from input

    Output on the right side
    [​IMG]

    Input on the right side
    [​IMG]

    Top view

    [​IMG]

    Inside view

    Output transformer very close to the output. At 90 degree of the PT both horizontally and vertically.

    [​IMG]

    [​IMG]

    Not too much wire criss crossing or long runs.

    Of course I will dress the wires and add the resistors on the output jack for both the speaker load and feedback. Plus the mica cap on the master volume

    Please review and tell me if I should be able to eliminate the HUM

    I kept the placement of components as close I could from Rob's design.
     
  12. keedba65

    keedba65 Tele-Meister

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    The layout looks good to me.

    Good luck!
     
  13. BluesBlooded

    BluesBlooded Friend of Leo's

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    Andrew, I ordered from digikey.ca yesterday and got it today by fedex for only 8$ of shipping. That was great. Thanks for the tip

    I also ordered caps and such from thetubestore.com in Hamilton. The order got here today as well, but the clumsy mailman did not put the key in my box.:mad:

    Thanks Kevin!
     
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  14. frankenxtein

    frankenxtein TDPRI Member

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    The first amp I built , I wanted to box it up and send it to somebody. lol
    I haven't done one of these , on a board. Just built another amp based on Robs Push Pull Micro Deluxe in a cable TV box. It's quiet but under powered
    Some notes :
    http://el34world.com/Forum/index.php?topic=21486.0

    These things are so small , the board is kind of big (I'm too cheap) but , if your going for a certain look. ;)
    Tag strips and point to point is too cheap ;) it's easier if you lay your components out then position the tag strips. I'm using top and bottom of the tag strips. Things that need to change are on top , dropping resistors , cathode resistors , power supply connections for convenience of safe start up. Using cheap radial caps .... they go on the bottom of the tag strips , leaving top for resistors/wires. B+ wires on bottom except for the OT Plate.
    Someone told me if it was easy everyone would build their own amps :p .

    Some stuff that has worked for me:
    All AC connections , lamp (left out on this last one here) , power switch , fuse , power cord. to one side. I've taken a liking to 1m pots with a switch. Master volume on the Micro Deluxe and the Bright switch are closest to my power supply side of the box. The only AC on the other side is the signal.

    This is the first time I laid the heater wires down on the chassis. Having them up 1 inch above in 3 other amps. I guess it would depend on the design. I think I like adding the heaters last above all the stuff. Really quiet that way and one doesn't mess with the other. I used used in the first attempt at building one of these , I thought they were noisy. I added them as back up but thought using a tube rectifier was quieter. I really don't know too much though so ...... probably BS eh?
    Although my amps are kinda crude they are all tube.

    This last adventure was somewhat a disappointment and a success. It's a very quiet amp compared to my SE amps. It isn't loud so using it in a situation where you need a over the top nasty sound , at acoustic guitar levels. This is the one does that. The disappointment is my PT isn't enough to get a clean sound I want , at a little higher volume.

    Someone said to have the PT center tap attached to the first filter capacitor ground point. They were building something else but , I thought I'll try that.

    Fixing to swap some parts into the other Micro Deluxe based chassis that has the power to get the B+ needed for my 12BH7A . I'd swap power supply's but their not the same design. This one will become a 6QA5 or 6BQ5 probably with the others VM 733 Output transformer.

    Last numbers
    V2 Push Pull
    12AU7 (Baldwin NOS)
    plates 287.1v drop is 11.89v using @818 ohm resistor

    ( 11.89v divided by 818 = 0.01453 X 287.1 = 4.173 )

    V1 12AT7 (JJ New)
    p1- 136.8v
    p3- 1.99v
    p6- 133.1v
    p8- 2.0v
     

    Attached Files:

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  15. frankenxtein

    frankenxtein TDPRI Member

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    In other chassis now , sounds good
    V2 (12BH7A RCA)
    Plate 354.9v
    Cathode 15.97v
    675 ohm cathode resistor
    (15.97 Divided by 675 = 0.023659 X 354.9 = 8.39)

    V1 (12AT7 JJ)
    P1 146.v
    P3 2.18v
    P6 142.8v
    P8 2.22v

    Then I changed cathode resistor to a 817 ohm

    V2 (12BH7A RCA)
    Plate 361v
    Cathode 16.85v
    817 ohm cathode resistor
    (16.85 Divided by 817 = 0.02062 X 361 = 7.44)
     
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  16. frankenxtein

    frankenxtein TDPRI Member

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    Used used .... What the heck does that mean ? lol Used "Diodes" You probably figured that out ;) It would be interesting to know how to properly tie the Deluxe Micro Preamp to the input of other power tubes like , 6AQ5 , 6V6 , 6BQ5 :D
     
  17. robrob

    robrob Poster Extraordinaire Ad Free Member

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    To properly tie the Deluxe Micro preamp to other single ended power tubes you simply have to lower the power tube grid stopper (470k below) and grid leak resistors. The power tube grid leak is the 1MA master volume pot.

    For the 6V6 you would need to change the grid stopper to 15k and change the master volume to a 250KA pot. For other power tubes look a their spec sheet to determine the max allowable grid resistance and change the grid stopper + master volume to keep the resistance below the max.
     
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  18. frankenxtein

    frankenxtein TDPRI Member

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    Thank you very much. :) I'll have to get into the amps I've added your preamp to , they work but I figured they might be hooked up improperly (all of them). This should keep me busy for a bit. It is more satisfying understanding why these things work. Where as starting out is more like paint by number.
    Should the 1meg master volume pot on my latest build with the Push Pull 12BH7 be different too? That one is kind of confusing. The layout is showing the same 1meg pot but , the note below the little insert is 500k pot? Other than the PT , OT , and the 12AT7 instead of a 12AY7 ... ... er no headphone jack. It's pretty much what's there in that layout.

    PS: I ordered a couple of Audio taper 250k's and 500k's , just don't have any with the short shaft pots that I'm using. 6BQ5 shows a max of 1meg grid #1 ..... Tube Depot is across town ;) so they love me :p
     
    Last edited: Feb 8, 2017
  19. BluesBlooded

    BluesBlooded Friend of Leo's

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    Preparing an order from McMaster and looking for turrets solder terminal and cannot find it. I would've been sure they had about everything possible.

    Anyone knows if they do and under what name or even better the item number?

    Thanks
     
  20. Dan Miller

    Dan Miller Tele-Meister

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    I don't think McMaster carries them. I order mine from Watts Tube Audio (http://tubeamplifierparts.com/turre...-Board-Terminals/p/41739143/category=11567061).

    If you don't already have one, you can get the #32 drill bit from McMaster.
     
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