In Reply to: RE: Stereomour w/45s questions posted by Jim_R on September 22, 2009 at 14:46:57:
No, the primary impedance design target is 4K for the new Bottlehead transformers. (Actually it looks like about 3947 ohms into 8 ohms on the 8 ohm tap, 3538 at 16 ohms with the new design). At the standard maximum operating point for the 45 (275v, 36mA) my nominal load design target is 3809 ohms. The RCA standard of 4600 ohms is a bit conservative relative to my nominal. But I will say, the best sounding 45 amp I've ever heard used a TFA-2004Ni at 3000 ohms so I am pretty confident that this load is going to sound good.An interesting third option is to set the amp up for 45 operation but plug in a 2A3. The voltage and current will be very close to the 45 design point, the output power will be in between the 45 and 2A3 levels, and the 2A3 will last longer at the more conservative operating point.
I have a shunt-regged 45 option in mind as well, using Zeners - not as good as a tube or hybrid regulator, but might be a modest improvement. No work on that until we get the basic product done though!
Edits: 09/22/09
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Follow Ups
- RE: Stereomour w/45s questions - Paul Joppa 22:00:05 09/22/09 (4)
- RE: Stereomour w/45s questions - jtkarma 04:00:07 09/23/09 (3)
- RE: Stereomour w/45s questions - tsingle999 05:49:07 09/24/09 (1)
- RE: Stereomour w/45s questions - jtkarma 07:08:21 09/24/09 (0)
- RE: Stereomour w/45s questions - Jim_R 05:05:35 09/23/09 (0)