Compact 2 Tube Reverb Layout

Discussion in 'Shock Brother's DIY Amps' started by robrob, Jun 16, 2014.

  1. robrob

    robrob Poster Extraordinaire Ad Free Member

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    Last edited: Jun 17, 2014
  2. Phil_tre

    Phil_tre Tele-Holic

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    Very cool Rob ! but how do you open a .diy file ?? I'm on a Mac, OSX 10.9.3...

    Thanks

    Phil.
     
  3. Commodore 64

    Commodore 64 Friend of Leo's

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    Nice pic, I downloaded it for future use. I have a couple tanks and transformers at home right now, just need to figure out where/how to use them.
     
  4. robrob

    robrob Poster Extraordinaire Ad Free Member

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    The layout was created using the easy to use and free DIYLC (Layout Creator) and from the DIYLC website:

    platform independence, will run on any machine having Java JRE/JDK 1.6.0_10 or newer
     
  5. robrob

    robrob Poster Extraordinaire Ad Free Member

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    Here's the bill of materials:

    [​IMG]
     
  6. LeroyBlues

    LeroyBlues Tele-Holic

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    So what would it take to make this a stand alone reverb unit? This looks simple enough, and I'd like to make one for the 5f1, and 5e3, I made a few years back. I'd need a power transformer and a rectifier, tube or diode, right? And what else? Any ideas or information, or is this not possible?
     
  7. robrob

    robrob Poster Extraordinaire Ad Free Member

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    This reverb circuit is designed to tap and return the signal between two preamp stages so it should work with amps with fx loops but it would not work with a guitar or mic connected directly to its 'Signal In.' For that you should be able to easily use the unused half of V2 as a preamp. I'm building a prototyping board and this would be a good idea to test.

    For an fx loop only stand alone reverb you would need to add a power transformer, rectifier and filter caps to deliver 400v DC (with step down to 240v) and 6.3v AC for the tube heaters. If you go with a tube rectifier you'll also need 5v AC for the cathode heat. To keep it compact I'd recommend going with 1N4007 diodes for rectification.
     
    Last edited: Jun 17, 2014
  8. robrob

    robrob Poster Extraordinaire Ad Free Member

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    Here's the stand alone design which has not been tested yet. The power transformer and rectifier are not shown:

    [​IMG]
     
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  9. LeroyBlues

    LeroyBlues Tele-Holic

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    It's got me thinking. I'll keep checking in.
     
  10. andyfromdenver

    andyfromdenver Friend of Leo's

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    Cool thread!

    I pulled the add-on two tube reverb from Clark Amps out of my Vox, cause something is popping and acting up. Tube swapping did nothing, so I did the hard thing and ripped it out, which will be a mega pain to rewire in, there wasn't enough wire length to work on the reverb without removing it. (I'm thinking a plate resistor is bad or something)

    I may email him and ask permission to post the scheme, cause it's biased and different from the fender style. If it's a known design once I draw it out, I'll link it.

    I plan to draw it out maybe any interested peeps pm in a week or so (need to rehearse for a show).
     
  11. robrob

    robrob Poster Extraordinaire Ad Free Member

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    Here's the schematic from the AA1164 Princeton Reverb showing the 'add on' reverb circuit shown in the first post:

    [​IMG]

    The 12AT7 Reverb Driver is using both halves of the tube in parallel to amplify the signal to drive the reverb transformer. The reverb transformer exchanges voltage for current to drive the tank input transducer (simply an electromagnet that physically moves the spring). The tank's output transducer turns the spring movement back into a weak electrical signal which the recovery amp (half of the 12AX7) amplifies to send out the reverb level pot.

    When the reverb pedal's switch is closed it grounds the recovery amp's grid to kill the reverb signal.

    Note that all of the signal flows through the reverb tank so this circuit's output is 100% wet. The dry signal bypasses this circuit through the 'tap circuit' made up of the paralleled 2.2M resistor and 10pF bypass cap shown at the top of the layout diagram.

    [​IMG]
     
    Last edited: Jun 18, 2014
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  12. Commodore 64

    Commodore 64 Friend of Leo's

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    I'm confused. I see diode rectifiers and a PT, so they do appear to be shown. What are the specs on the PT? We want 400v rectified, so something like 300-0-300 or 330-0-330?
     
  13. robrob

    robrob Poster Extraordinaire Ad Free Member

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    I edited the layout after I posted so it says "PT not show" but it is. I don't know the power transformer specs yet. It will be a low power PT with center taps for the main output and filament heaters. If you use a PT with no center tap for the B+ then you must use a 4 diode rectifier (bridge rectifier).
     
    Last edited: Jun 19, 2014
  14. Commodore 64

    Commodore 64 Friend of Leo's

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    I took the liberty of reposting this for you over at ppwatt. I hope that's OK. I'll share anything I learn there. (Or you should join!) http://www.wattkins.com/node/23047

    I have most of the parts needed. Just need to choose a PT. I have an MPS 325.2 just sittin' (it's my back-up/guinea pig). I'd like to help you/build this too (Easier to troubleshoot new designs when more than 1 person is doing it, IMHO).

    Here's a ppwatt schematic:
    [​IMG]
     
  15. robrob

    robrob Poster Extraordinaire Ad Free Member

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    I have a 375-0-375 PT and a variac for my prototype setup so I can play with the voltage to get the 400v B+ needed but I have to build the circuit first. I have separate 6.3 and 5v transformers so the variac doesn't screw with their output.

    Commodore, I posted in your cross-thread.

    I added a 'Dry Signal Out' jack to the stand alone circuit which simply keeps you from having to use a guitar Y-cable to feed the amp and the reverb unit. If your amp has two or more inputs you could plug your guitar into the reverb units input and patch the 'Dry Signal Out' into one amp input and the 'Wet Signal Out' into the other and control the volume of the reverb using the 'Reverb Level' pot.
     
    Last edited: Jun 19, 2014
  16. robrob

    robrob Poster Extraordinaire Ad Free Member

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    I found this Weber 'Adverb' layout which uses a 6k6 to drive the reverb transformer:

    [​IMG]

    Three tubes, more controls and much more complexity.
     
  17. robrob

    robrob Poster Extraordinaire Ad Free Member

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    I removed the grid stop resistor since the Fender 6G15 and Weber Adverb don't use one. I also suggest using shielded wire for the connection from the input jack to tube V2B grid (ground the shield only at the input jack end):

    [​IMG]

    Here's the bill of material for the stand alone compact reverb:

    [​IMG]

    Here's the DIYLC file for the stand alone circuit: http://robrobinette.com/images/Guitar/5E3P_Build/Tube_Reverb_Stand_Alone.diy

    I'll report here when I start testing the circuit.
     
  18. robrob

    robrob Poster Extraordinaire Ad Free Member

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    Last edited: Jun 21, 2014
  19. zeppelinofled69

    zeppelinofled69 Tele-Meister

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    I just got a small power transformer with 2 non center tapped secondaries.

    1 secondary gives me a rectified, and unloaded voltage of 425VDC
    the other is a 6.3V secondary.

    I think I can make this transformer work, as long as it can supply enough current.

    Any idea how much current this might require from the HT winding?
     
  20. robrob

    robrob Poster Extraordinaire Ad Free Member

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    It's going to be a very small current draw with the HT powering only one 12AX7 and one 12AT7--probably less than 15 milliamps. The heater draw will be 0.6 amps.
     
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