Hoffman Amplifiers Tube Amplifier Forum
Other Stuff => Effects => Topic started by: TwoAlpha on June 30, 2015, 02:39:10 pm
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Here we go!
As mentioned over in the Introduce Yourself section, my only previous build, and it wasn't even tubes, was a Dynaco Pat-5 way back in 1974 or so.
At first the thought was to get into tube building with an amplifier, and since my preference leans towards simpler amplifiers without built in effects, I had been browsing through old Fender and Marshall schematics, and the various kit suppliers web sites, looking for an amplifier that might fit in between the ones that I have.
There was a bit of a problem though, I've already got a few decent tube amps around the house right now so there really isn't a pressing "need" for another.
For some reason the Fender Vibrato circuits had caught my attention as I was looking at the various schematics, I spent a bit of time learning more about them. The ReVibe was showing up in the various searches and it seemed like the perfect project for me, a combination of Leo's stand alone reverb and one of his best tremolo circuits.
I've made changes to the schematic and layout, just couldn't help myself. The reverb is in front of the tremolo now and has had the original buffer added back in, using the unused portion of the phase splitter 12AX7. My thinking was to have the configuration more in line with the way it was back in the early and mid sixties.
The one other change that might be made would be to make it so it could be used in an effects loop.
Here are my current schematic and layout, the parts are on the way from Hoffman Amplifiers as of yesterday morning. Any comments or suggestions will be greatly appreciated.
edit: updated both schematic and layout to include a grid leak resistor on V4-B, thanks sluckey!
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I like this idea. Looking forward to see the project grow. Keep us posted.
BTW, you need a grid leak resistor on the grid of V4B. Several easy ways to add to your layout. I would just connect a 1MΩ resistor between the wiper of the MIX pot and the ground buss.
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Thanks for catching that for me sluckey, I can almost see how I missed that one! It's fortunate for me that I won't have to jury rig it onto the board I've already ordered.
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Wow, the parts arrived at my door this morning, very impressive considering the potential for sitting in limbo at the border! Have to finish off a repair in progress before I can get started on it.
I see another mistake I've made already, there are turrets in the mounting holes on my nice new board!
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Wow, the parts arrived at my door this morning, very impressive considering the potential for sitting in limbo at the border!
:blob8:
........ there are turrets in the mounting holes on my nice new board!
They drill out pretty easy from the back. :icon_biggrin:
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It was a simple task getting those extra turret's out, hopefully the rest of my errors will be that easy to fix.
The temptation to load up the board was too much to resist, it ended up looking a little industrial/rugged but should work ok. Time to get some holes in the chassis so I can start mounting things up.
(http://i65.photobucket.com/albums/h231/jdglencross/ReVibe/DSCN2241_zps4pedkesm.jpg)
This board is almost as long as the chassis, I can see now how sluckey made better use of his board area so that it could be shorter and leave quite a bit more room. I should still be ok though, one more tube socket but no cap cans to squeeze in.
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Board looks good.
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Thanks sluckey, striving to be neat and orderly but it's a bit out of character for me. :smiley:
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A bit more progress, managed to get all but one of the holes cut into the chassis. The last one will be done once I get my hands on a Fender pilot lamp assembly.
(http://i65.photobucket.com/albums/h231/jdglencross/ReVibe/DSCN2242_zpsa3bnijz3.jpg)
(http://i65.photobucket.com/albums/h231/jdglencross/ReVibe/DSCN2244_zpshsf34rva.jpg)
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Time to get some wiring done.
(http://i65.photobucket.com/albums/h231/jdglencross/ReVibe/880256d2-50f5-49a2-a0bc-c86d810031c0_zps4rujmtmm.jpg)
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Is that a 'short' reverb spring tank?
If so, the shorter tank will limit the reverb depth, fullness/lushness.
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Yes, it's a Ruby Tubes tank out of a Traynor TRM-30 that I just happened to have laying around. We'll see how long it survives.
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What are the specs for that tank? The revibe will want...
Input Impedance 8 Ohms
Output Impedance 2250 Ohms
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The model number is a bit different, RRVSA2E1A2C1B. It's a short tank with two transmission springs, the dc resistance is 47 ohms for the input, 48 for the output. Looks like I'm going to be ordering a new tank.
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... The revibe will want...
Input Impedance 8 Ohms
Output Impedance 2250 Ohms
... the dc resistance is 47 ohms for the input, 48 for the output. Looks like I'm going to be ordering a new tank.
D.C. resistance does not equal impedance. Looking for "Traynor TRM30 Reverb Tank" yielded results for 600Ω input, 2250Ω output impedance tanks. You'll need to order a tank, but only because the desired tank will be 8Ω input impedance rather than 600Ω.
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Thanks for that HotBluePlates, I had stumbled across a conversion chart which gave me enough information to know that the tank I had did not mesh with what the revibe requires. May as well get a proper Fender style replacement now.
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Looks cool. I want to build one.
It might be nice to have a switch to put the vibrato before or after the reverb.
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Very nice work. Nice idea as well.