Posted by 2wo [ 71.242.20.199 ] on June 29, 2006 at 21:25:24:
In Reply to: 6Ah4 Amp posted by manualblock on June 28, 2006 at 17:58:13:
Hi M,
I am not familiar with the 6AH4, so I looked it up in my trusty ‘GE essential characteristics’ ( a great quick reference book by the way).
The kicker here is the high plate resistance (Rp), requiring the < 7K transformer. Most of the good affordable multiple tap transformers, like the Lundahl or James run about 3K to 6.5k. The higher K transformers tend to be for the high power triodes like the 845, so get expensive.
If the designers feel that 6.5K will do. The James transformers at about $150- $200 a pair are a fine choice and will be right at home in any number of future amps. I have a pair in my DRD amps.
If 6.5K is to low, or over budget, take a long look at the Hammond 125 series. At $20-$35 each, they are not the last word in thunders bass, or shimmering highs but are pretty pretty damn good for the money. Have a look at Angela. http://www.angela.com/catalog.html
Keep in mind that I would not expect more than a 1-1.5W with this tube. So thunder is probably not in the program.
I don’t want to dissuade you from your project but have you considered the 2A3, at about $30…John
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