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Almost done 2a3 parafeed with Magnequest FS100 PC 60mA/120H
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Posted on February 8, 2024 at 06:49:42 | |
Posts: 4109
Joined: March 28, 2001 |
![]() tfa 2004 jr nickel output It is based on this schematic: But parafeed: Anyone out there also have a project with the FS100PC or FS100PF? This is the post by Paul Joppa that convinced me to go for it (15 years ago): Posted by Paul Joppa (P) on February 6, 2009 at 18:41:15 Just a thought for anyone interested ... In my experience, a larger impedance plate load always makes for better sound in parafeed. I've tried, or at least listened to, a wide variety of chokes as well as current sources. I once built a preamp with switched plate loads of 20, 24, 40, or 48 henries, for example (using 6BL7s parafeed to B7-5K) plus a current source - believe me, every inductance increase was an improvement. Extrapolating that experience, here's a really wild idea - get a pair of these gapped for 60mA and couple to a TFA-2004Ni with a 27uF capacitor. If you can afford the nickel core TFA (still the best sounding OPT I've ever heard), this choke is neither inappropriate nor unreasonably expensive. Feed it with a 2A3 running 275v at 55mA - cathode resistor 910 ohms - or if you're feeling flush, one of those 2.5v 300Bs at 300v, 60mA (same cathode resistor). Of course the greatest benefit will be in the bass, so use this to drive some ginormous efficient speakers with killer bass. I predict you will never hear sound as good with a 2A3. This was a reply to Mike's last call for these chokes: On the bright side--- these are really great plate chokes--- and we can airgap them for a range of plate currents--- all of the units are designed to handle 500 vrms at 30 hertz AC signal. DC (plate current) capacities are listed below. Each unit uses our EL coil design strategy (our SUPER designation). Each unit will be supplied with 18 gauge EE teflon lead wires. Each choke uses teflon insulation. We do NOT formally warrant this choke for high voltage applications. Each choke is wax impregnated. The nominal DCR (winding resistance) of this choke is 170 ohms. |
RE: It was a one off series in 2009, posted on February 14, 2024 at 08:54:27 | |
Posts: 38
Joined: February 17, 2005 |
![]() thanks, the bell ends look good in white. reminds me of these 5504 |
With tubes. First smoketest passed (ht off), posted on February 15, 2024 at 07:15:34 | |
Posts: 4109
Joined: March 28, 2001 |
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RE: Almost done 2a3 parafeed with Magnequest FS100 PC 60mA/120H, posted on February 16, 2024 at 08:13:06 | |
Posts: 4109
Joined: March 28, 2001 |
![]() Another pic |
I will say, posted on February 16, 2024 at 08:45:48 | |
Posts: 11158
Location: NJ Joined: December 11, 2000 |
hope they sound as great as they look!
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Better! nt., posted on February 16, 2024 at 09:23:23 | |
Posts: 4109
Joined: March 28, 2001 |
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Just kidding. Beauty is in the eye of the beholder, posted on February 18, 2024 at 04:02:27 | |
Posts: 4109
Joined: March 28, 2001 |
I'm happy with the way it looks and sounds. |
Power supply schematic, posted on February 20, 2024 at 00:23:04 | |
Posts: 4109
Joined: March 28, 2001 |
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Amp schematic, posted on February 20, 2024 at 00:25:31 | |
Posts: 4109
Joined: March 28, 2001 |
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RE: Amp schematic, posted on February 21, 2024 at 05:53:48 | |
Posts: 38
Joined: February 17, 2005 |
I'd like to see the underside if possible |
RE: Amp schematic, posted on February 22, 2024 at 02:26:52 | |
Posts: 4109
Joined: March 28, 2001 |
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RE: Amp schematic, posted on February 22, 2024 at 02:27:21 | |
Posts: 4109
Joined: March 28, 2001 |
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RE: Amp schematic, posted on February 22, 2024 at 06:07:20 | |
Posts: 38
Joined: February 17, 2005 |
thats wild! thanks |