Tweet
Originally posted by g-one
View Post
-
I didn't really check that closely but it has to have the reference resistor, I can't see how the thing would work without it and it works pretty good. The web schematic has to have an error in it. Anyway that's all academic now, the customer has picked it up after we played it through my test cabinet for a while and that thing has some tone, punch and a reasonable amount of power. The high end distortion gets a little radical but I think that's the charm of the amp, it has just the right amount of rectifier sag that would make an old blues man blush... I bet it would be superb for harmonica as well.... That's $1.00 for the chalk mark and $49,999.00 for knowing where to put it! -
The big reveal
Just thought I would come full circle on this one and show you the fully restored amp...
Sorry, I just noticed that the pictures are sideways... D#$!m iPhone!... That's $1.00 for the chalk mark and $49,999.00 for knowing where to put it!Comment
-
That's a rats nest PTP! They can be pretty quiet if done with thought but a PITA to repair...Comment
-
There's another mistake on the "web" schematic. The 6sc7 has the cathodes of both triode sections internally connected. So, the "inverter" stage does not have a grounded cathode, its cathode shares that 3.3K resistor and bypass cap used by the triode section above it. The author of the schematic probably mistook the grounded shield pin on the 6SC7 (metal jacket tubes!) for the 2nd cathode.Comment
-
I do believe that the 6SC7 has a shared cathode, internally.
http://www.r-type.org/pdfs/6sc7.pdfComment
-
I do believe that the 6SC7 has a shared cathode, internally.
http://www.r-type.org/pdfs/6sc7.pdfComment
-
Maybe I phrased that unclearly- I stated that there was a mistake in the schematic. Then I stated that the 6sc7 has its cathodes internally connected. The schematic shows the cathodes as separate, one going to ground, one going to a 3.3K resistor. So the mistake is that they are shown as NOT internally connected. Whoever drew it up mistook the shield pin on the 6sc7 for a 2nd cathode.Comment
Comment