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Here's the Jack Darr schematic


 :
1/29/2006 2:02 AM
Steve A.
Here's the Jack Darr schematic
    Thanks for the tip! The schematic was on Page 109 in the edition I have:  
 
http://www.blueguitar.org/new/schem/electar/Ediphone_EA-50.GIF  
 
    I was going crazy trying to find the split plate load shown in the schematic I posted earlier! :(  
 
Steve Ahola
 
1/29/2006 4:11 AM
Steve A.
To thoroughly confuse everybody...
    ... I decided to rename the files referenced in this thread. :(  
 
    The original EA-50 file is now:  
 
http://www.blueguitar.org/new/schem/electar/Epiphone_EA-50-early.jpg  
 
 
    The Jack Darr schematic is now:  
 
http://www.blueguitar.org/new/schem/electar/Epiphone_EA-50.GIF  
 
    I drew up a wiring diagram of the "virgin" EA-50 (although this drawing does show the new power supply caps):  
 
http://www.blueguitar.org/new/schem/electar/Epiphone_EA-50_layout.GIF  
 
 
    And the chassis pix are now:  
 
http://www.blueguitar.org/new/schem/electar/modnotes/Epi_EA-50_pix.zip  
 
--Enjoy! This would be a slick point-to-point project, with no circuit board just 3 terminal strips and 5 tube sockets.  
 
Steve Ahola
 
1/30/2006 4:52 PM
Steve A.
Slick tone control mod...
    The modded EA-50 had a 100k audio pot with a rotary off switch which replaced the rotary on-off switch. The "top" of the pot connected to the "top" of the volume pot, and is connected to the wiper with a 0.01uF cap. The "tail" of the 100k pot was connected to ground.  
 
    With the pot in the lowest position, it cuts the highs with a parallelled .01uF cap and 100k resistor going to ground. With the pot in the highest position the cap is removed from the equation and we have a 100k load to ground. And in the intermediate positions you get a nice mix of the cap and the resistances...  
 
    FWIW the only other mod I noticed on that EA-50 was a 220k grid stopper after the volume control instead of a 100k one in the schematic. But there may have been other mods I didn't notice.  
 
Steve Ahola
 
2/7/2006 1:16 AM
Steve A.
OT for 6AQ5's?
    Just wondering what OT would work with a pair of 6AQ5's in push-pull... this amp sounds really smooth and would be a good alternative to a Champ, which is kinda rough. This would be a fun project to build!  
 
Steve Ahola
 
2/7/2006 7:53 AM
Sonny ReVerb
Looks like a Hammond 1608 or 1609 would work fine:  
 
http://www.hammondmfg.com/1608.htm  
 
A pair of 6AQ5's in PP put out around 10 watts. I'd like to try something like this as well; I got several NOS 6AQ5's in a batch of tubes I bought at a Ham Fest last year.  
 
Sonny
 
1/31/2006 5:11 PM
Sonny ReVerb Link to scans of Jack Darr Amplifier Handbook
I found a site that has the scans of the Jack Darr Amplifier Handbook someone mentioned. It's broken up into several PDF files:  
 
http://www.pacificrecone.com/JackDarrBook.html  
 
Enjoy!  
 
Sonny
 
2/1/2006 5:16 AM
TD Madden

I cna never find Section Three of the Handbook, most likely the schematics....anyone seen that scan?
 

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