Harvard reverb - first finished build in a while

Discussion in 'Shock Brother's DIY Amps' started by Nickfl, Mar 29, 2020.

  1. Nickfl

    Nickfl Tele-Afflicted

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    Looking back in my files, it looks like my last build was finished some time around June of last year... so I guess I'll file finishing this one under the bright side of the world grinding to a halt.

    Really though, my dry spell had more to do with moving to a new house last summer and then the birth of my second child in November, but lots of things converged to get me back to work with a soldering iron in my hand recently and the upshot is that a build that I started thinking about some time in late 2018 is now ready to fire up for the first time.

    This is my Harv-o-verb, basically a 5F10 and a 6g15 reverb mated together inside the same chassis. I started thinking about this project back in December 2018 in this thread.

    Then started working on it last September when I posted a thread about scratch making the chassis.

    I got as far as populating the eyelet board before life got in the way a kept me away from my workbench until about two weeks ago. I've been working on it here and there since and finally got a couple of solid hours during the kids nap time this afternoon to finish it up.

    Here are some gut shots of the finished job.

    The Harvard section:

    IMG_20200329_184024.jpg

    The reverb section:

    IMG_20200329_184028.jpg

    And the whole thing in all of its single channel 8 tube glory:

    IMG_20200329_220935.jpg

    I was very happy to find it worked flawlessly (other than having to swap the OT primary leads due to NFB squeal) and to my surprise and delight it is absolutely dead quiet at idle, so the time and effort spent on my layout paid off!

    My initial impressions of the tone are very favorable, though I've learned that those initial impressions should always be taken with a grain of salt...

    Pics in the cab coming soon, and maybe a sound clip or two if I have any spare time...
     
  2. jsnwhite619

    jsnwhite619 Friend of Leo's

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    I love a Harvard! Nice build!

    Sent from my moto g(6) using Tapatalk
     
  3. jsnwhite619

    jsnwhite619 Friend of Leo's

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    Is it kind of like a tweedy Princeton Reverb?

    Sent from my moto g(6) using Tapatalk
     
  4. Nickfl

    Nickfl Tele-Afflicted

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    On paper it sort of is, but from my 10 minutes so far of playing it I would say it is starkly different.

    The harvard section (which I built so it can be plugged into without the reverb) is a lot fuller sounding than my PR build and IMO has a much better overdrive, I've never been all than happy with the blackface princeton's dirty tone.

    My initial impression is that the reverb is also very different from the blackface reverb, and much superior. Kind of like the difference between the BF tremolo and the earlier bias vary versions, more complicated, but lusher and fuller. Again, initial impression on a new build, so there may be some rose colored hearing happening... but I think it may really put the BF Princeton Reverb to shame.
     
  5. FenderLover

    FenderLover Poster Extraordinaire

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    Just went back and looked at your schematic.
    Bravo, sir. Bravo.
     
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  6. jsnwhite619

    jsnwhite619 Friend of Leo's

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    Demo clips!

    Sent from my moto g(6) using Tapatalk
     
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  7. Nickfl

    Nickfl Tele-Afflicted

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    As promised, some more pictures of everything installed in the cab:

    IMG_20200330_152848.jpg

    The speaker is a Weber 12a125, I had to take off the dust cover to clear the 6sq7 tube. That speaker was in my 6g3 inspired amp originally but I ended up deciding I wanted a British voiced speaker for that amp and it has been sitting waiting for its moment ever since, I think it is a good match for this build.

    IMG_20200330_155116.jpg

    Note the different colored chicken head knobs for the reverb controls and the amp controls. This was completely random chance as I had not thought it through and these were the last 5 chicken head knobs in my parts stash. Total lack of planning on my part, but it worked out perfectly!

    IMG_20200330_155139.jpg

    And the front. I have been wanting to do a wide panel type cabinet for a couple of years and actually started building this one two years or so ago for a build that ended up going into an old reel to reel tape deck cabinet instead. When I decided to build this amp it seemed like a good reason to pull this cabinet off the shelf and put some "tweed" (fabric store twill actually) on it.
     
  8. El Tele Lobo

    El Tele Lobo Poster Extraordinaire Silver Supporter

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    Nice! When do we get to hear it?
     
  9. MasterEvan07

    MasterEvan07 Tele-Meister

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    This is cool. I've been wanting to make a 5E3 again, but one with properly implemented reverb would be awesome.
     
  10. AlbertaGriff

    AlbertaGriff Tele-Afflicted

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    Wow, sweet!

    Like others, I would love to hear what this sounds like.
     
  11. chas.wahl

    chas.wahl Tele-Meister

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    Since your build is dead quiet at idle, I'd like to see what the layout of transformers and chokes is -- if you have photos, or a diagram, that is. Definitely not asking for you to disassemble it. Nice concept and execution. Looking forward to hearing it playing.
     
  12. jsnwhite619

    jsnwhite619 Friend of Leo's

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    I've built a few stock Harvards, and using the standard layout and good lead placement, they are pretty easy to get dead quiet up to 9-10 on the dial.
     
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  13. Nickfl

    Nickfl Tele-Afflicted

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    Obviously you can tell where the PT is and how it is oriented from the gut shots, here I've indicated how the OT and reverb transformer are mounted:

    ink (1).png

    The other factor would be the way I've laid out the eyelet board to keep the filter caps as close as possible to the tubes they are supplying and tried to keep the DC supply loops from those caps as small as possible.

    As @jsnwhite619 indicated, the Harvard is inherently pretty quiet and that is actually aided by my having used a metal tube for the first gain stage of the Harvard section here with its grounded metal shell providing additional shielding in that noise sensitive position. Outboard reverbs are notoriously prone to hum, but the extra filtering from the Harvard, the hum rejection of the Harvard's push pull power section and the fact that it is all mounted in the same chassis with a shared ground scheme have eliminated a lot of the things that can cause noise issues in more traditional builds.
     
    Last edited: Apr 4, 2020
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  14. Nickfl

    Nickfl Tele-Afflicted

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    I'm still really loving this amp, I spent some more time with it this afternoon and decided to record a demo. I found that the dynamic mic I tried at first made it sound really dull and ended up going with a large diaphragm condenser, which recorded much more true to the actual sound in the room. The guitar is a telecaster and I switch back and forth a bit between neck and bridge pickups.

    The first section is with the volume at about 11 o'clock and reverb turned down fairly low. Second section, volume 11 o'clock and reverb turned up. Last section volume up to 4 o'clock and reverb turned back down just a bit.

     
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