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Tube DIY Asylum Do It Yourself (DIY) paradise for tube and SET project builders. |
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Tube DIY Asylum Do It Yourself (DIY) paradise for tube and SET project builders. |
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In Reply to: Lafayette schematic posted by jec@afo.net on June 19, 2015 at 12:55:06:
That setup uses AC heating. You need tubes with a hum bucking heater to have any chance at an acceptable residual hum level. The obvious choice is buying culled phono grade Sovtek 12AX7LPSes from a reliable dealer, like AA sponsor Jim McShane.The 0.01 μF. O/P coupling caps. combine with the downstream I/P impedance to form a high pass filter. FYI, those caps. combine with 100 Kohms to "corner" at (sic) 159 Hz. Working into 500 Kohms gets the "corner" down to a marginal 31.8 Hz. Don't connect the Lafayette unit to a SS line stage, unless modifications are made.
I hope I'm wrong, but it seems that unit was intended to be used with old GE carts., whose internal inductance contributes to the RIAA EQ. Another "gotcha" is the I/P impedance. Modern MM level carts need a 47 Kohm I/P impedance, not 6 Kohms.
Eli D.
Edits: 06/19/15
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Follow Ups
- RE: Lafayette schematic - Eli Duttman 20:11:38 06/19/15 (5)
- Chrome Cutie Preamps have .1 uf final cap; not .01...Hum is easily controlled... - Interstage Tranny 08:56:11 06/21/15 (2)
- RE: Chrome Cutie Preamps have .1 uf final cap; not .01...Hum is easily controlled... - Eli Duttman 10:47:11 06/21/15 (1)
- RE: Chrome Cutie Preamps have .1 uf final cap; not .01...Hum is easily controlled... - jec@afo.net 14:32:31 06/21/15 (0)
- And the 2nd Stage is Grid Leak Bias :( - Triode_Kingdom 20:57:52 06/19/15 (1)
- RE: And the 2nd Stage is Grid Leak Bias :( - Eli Duttman 09:37:35 06/20/15 (0)
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