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Started by 5thumbs, November 10, 2009, 02:52:23 PM
Quote from: 5thumbs on November 10, 2009, 02:52:23 PMI work on Kustom Tube 12A combos from time to time and have a couple of these amps kicking around my house at any given moment. If you replace the 4558 IC with something hi-fi like an OPA2134PA, these $100USD amps are positively charming and useful as a practice, recording or workbench amp.Since nobody else has previously posted this schem, I figured I'd share it with y'all. Good luck!
Quote from: joecool85 on November 10, 2009, 04:27:28 PMWhats the difference you get when you change that chip? Better quality? Better tonal reproduction? Louder?
Quote from: J M Fahey on November 11, 2009, 08:54:26 AMIf someday you could post a couple of pictures, including some "guts", they will be welcome.
Quote from: phatt on November 11, 2009, 07:31:49 AMBTW I think the schematic has a bobo next to *R40 and R42* looks like a dead short to me as drawn that shorts out the secondary winding of the power transformer. Just thought I'd mention it.Cheers, Phil.
Quote from: J M Fahey on November 11, 2009, 08:54:26 AMHi PhattYes, you are right.Another error is the undefined connection between D42 and D45.I usually fiund many "official factory" schematics, with dumb unexplained errors.I guess that they are there on purpose, so any technician will recognize them as such, and in a service situation, the dead amp is there, on the bench, and the actual wiring can be checked, but a non-tecnician, who can read a schematic and solder but not really understand design, will fail when trying to clone something, based only on an Internet downloaded schematic.Even worse are "reverse engineered" schematics, when some component is not accurately read or some tracks get mixed.
Quote from: J M Fahey on November 11, 2009, 08:54:26 AMHi 5thumbs (I'd *love* to hear you tapping a 5 string bass he he), thanks for sharing.
Quote from: Brymus on November 14, 2009, 06:34:16 PMWhat kind of sound do the 4X4148s to ground give after the first triode?
Quote from: Brymus on November 14, 2009, 06:34:16 PMI just tried something similiar with red LEDs and found 2 sounded great but 4 only added a little dirt not very noticable.
Quote from: Brymus on November 14, 2009, 06:34:16 PMHow does the low plate voltage affect the clipping the make?My triodes are closer to 250V- 300V plate voltage 80v seems low.
Quote from: Brymus on November 14, 2009, 06:34:16 PMAlso why are they biased with 2k2 instead of 1k5 or 820r?Is it because of the low plate voltage?
Quote from: Brymus on November 14, 2009, 06:34:16 PMAnd finally have you tried added a bypass cap to either triode?Seems like the first one could have a 4.7uf on a switch for a nice warm boost or even a .2 - .68 for some top boost .Thanxs for sharing the schematic and pics,Its nice learning about new stuff.