Vibro Champ Build #2

Discussion in 'Shock Brother's DIY Amps' started by Phrygian77, Aug 31, 2019.

  1. Phrygian77

    Phrygian77 Tele-Afflicted

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    IMG_20190830_171812.jpg This starts with a 16" tall slightly deeper cabinet with blonde cosmetics. An Eminence 1028k is on the way. OT is a ClassicTone 40-18030, and the PT is a 40-18027. I'm going to try using the 550VAC secondary with a GZ34, and a Tung-Sol 6V6GT to see where that gets me. Plate voltage may end up too high, so I've got a JJ 6V6s I can drop in if needed. The 40-18109 with the 550 secondary, SS rectified, put me at 360 with a Tung-Sol 5881 running at 21 watts idle.

    This will be the first time I'll be be using mostly CC resistors, just for fun, and Sozo caps (except the tremolo). I'm going to sub in a .022 instead of the .047 for the mid cap. Mid resistor will be the stock 15k instead of a 6.8k. I'm not aiming for clean tones this time around.
     
    Last edited: Aug 31, 2019
  2. King Fan

    King Fan Friend of Leo's Ad Free Member

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    Sounds like a great plan. You made me look... at this:

    40-18027 copy.png
     
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  3. Phrygian77

    Phrygian77 Tele-Afflicted

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    I've been using them in my PR builds. I get around 415-422VDC with a GZ34 using the 630VAC secondary. I used the M6 version in my last Vibro Champ, since I knew it was going to be idling over 20 watts.
     
  4. Phrygian77

    Phrygian77 Tele-Afflicted

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    IMG_20190903_194959.jpg
     
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  5. TequilaCaster

    TequilaCaster Tele-Holic

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    Beautiful! My favorite amp! My favorite speaker too! I am sure your final product will be amazing.
     
    Last edited: Sep 3, 2019
  6. Phrygian77

    Phrygian77 Tele-Afflicted

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    I've never used one before, but it's supposed to be a copy of the old CTS alnico. I have two CTS orginals, and two recones in a Super Reverb. Awesome sounding speakers, so I'm looking forward to trying this out. I may put a pair in my brown Super build if I like it.
     
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  7. Phrygian77

    Phrygian77 Tele-Afflicted

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    The last Vibro Champ build, I did it with a 6.8k mid resistor, like the majority of blackface amps. With a 5881 output tube, and a bigger speaker, it was a lot like a non-reverb blackface Princeton.
     
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  8. Phrygian77

    Phrygian77 Tele-Afflicted

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    IMG_20190903_231847.jpg
     
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  9. tubedood

    tubedood Tele-Meister

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    Phrygian77 I am watching this thread like most of yours... Eagerly! You do great work and share ideas and tips we all benefit from.

    I used to have an old late 60s Vibro-Champ. She was in great condition. I sold it to buy Christmas presents a long time ago when I was a single Dad.
     
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  10. Phrygian77

    Phrygian77 Tele-Afflicted

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    I hear you, man. I sold my '70 Princeton Reverb during the recession a little over 10 years ago.
     
  11. Phrygian77

    Phrygian77 Tele-Afflicted

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    Also a single dad at the time.
     
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  12. Phrygian77

    Phrygian77 Tele-Afflicted

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    I'm fortunate to be in a position to be doing this right now. I've been building over the last several years, and I've been fortunate enough to attract locals. Since John McNeese left for Athens, there's been no one reputable to work on vintage amps in the area.
     
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  13. theprofessor

    theprofessor Friend of Leo's

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    That is a gorgeous cabinet, and I'm sure the amp will sound fantastic with that 1028k. I can't wait to see the build!
     
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  14. Phrygian77

    Phrygian77 Tele-Afflicted

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    Drilling and filing 16 gauge galvanneal, my least favorite part of a build using these chassis.

    IMG_20190929_010722.jpg


    Since the cabinet is deeper than a standard Vibro Champ cabinet, I drilled rear holes for the internal speaker jack, an extension cab jack, the RCA tremolo jack, and an NFB switch. Extension cabinet jack will be a Switchcraft 13A wired in parallel with the 12A jack. Transfer circuit on the 13A will switch to the 4 ohm secondary when an 8 ohm extension cabinet is plugged in. I did this on my last Princeton Reverb build also.

    Mounting holes for the grounds are also done. One thing about these Vibro Champ chassis, compared to the PR chassis from the same maker, is that the mounting holes for the PT are smaller and slightly off. I filed the mounting holes them to make it fit, but that's a pain. The next time I'm just drilling the holes slightly larger.

    Also the mounting centers for the 9-pin sockets are off. I had the same problem with the last VC build. I still need to file those to fit. Then, I may need to tweak some of the front panel holes. I didn't do it on the last build, but I should have because some things were slightly off. Although, you really had to look closely to notice.

    IMG_20190929_010752.jpg
     
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  15. Phrygian77

    Phrygian77 Tele-Afflicted

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    Spent a bunch of time today filing away on the holes in the front of the chassis to get the faceplate to line up better. Still have some more to do. I'd like it a little lower, but I can live with it.

    These were taken before I started ...

    IMG_20190929_131508.jpg

    IMG_20190929_131548.jpg

    IMG_20190929_131617.jpg
     
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  16. avspecialist

    avspecialist TDPRI Member

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    Beautiful so far, i’m looking forward to see the progress
     
  17. Phrygian77

    Phrygian77 Tele-Afflicted

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    I don't know why the mounting centers are wrong for the 9-pin sockets on these VC chassis, but their PR chassis have the correct spacing. Anyway, this was last of the filing that I had to do on the chassis. Now the real work can begin.

    IMG_20190930_183506.jpg


    Test fitting the faceplate and chassis in the cabinet...

    IMG_20190930_224157.jpg
     
  18. Phrygian77

    Phrygian77 Tele-Afflicted

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    IMG_20191003_231239.jpg
     
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  19. Phrygian77

    Phrygian77 Tele-Afflicted

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    IMG_20191005_151504.jpg

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  20. BigDaddy23

    BigDaddy23 Tele-Meister

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    Nice!

    In pic 2 above - What's that between the V2 and V3 sockets? A test point??
     
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