In Reply to: Just finished a 6EM7 amp! posted by Mike9186 on November 13, 2003 at 08:05:30:
Mike -Glad you like the amp, and thanks for the kind words. I've been away from the Asylum for a bit, so may have missed earlier postings.
This amp was a try at simplicity and low cost - and one that worked very nicely. I never wrote up the power supply formally as it was based on my junk box. I built the entire amp using parts I had lying around.
I've never tried parafeeding this design, but would agree with Bas's comments. Grab some good oil caps, you may be very pleasantly surprised.
I've never found that the 6EM7 needs grid stoppers in this (or several other designs). Then again, playing with the 6C45 and 417A's really made me appreciate them in other amps.
If it's running very hot, measure the voltages. The cathode resistor on the second section does dissipate a bit of heat, as it has 140v across it. As with most DC coupled designs the interactions between sections is a bit more critical than in cap coupled designs.
Lastly, consider trying different batteries. Ironically I did find that different NiMH batteries sounded different. I don't really want to trigger an "audiophile approved" marketing line for batteries! I'm using some "Rayovac Ultra" 1600ma Chinese made batteries currently.
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Follow Ups
- Re: Just finished a 6EM7 amp! - Gary Kaufman 11/13/0313:18:16 11/13/03 (3)
- He's back! - AnandR 14:55:22 11/13/03 (0)
- the amp is settling in - Mike9186 13:34:43 11/13/03 (1)
- Lastly, do you have any ideas where can I find some decent priced oil caps? - J Epstein 11:49:54 11/14/03 (0)