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SET Asylum Single Ended Triodes (SETs), the ultimate tube lovers dream. |
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SET Asylum Single Ended Triodes (SETs), the ultimate tube lovers dream. |
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In Reply to: RE: HF-81... posted by kevinkr on July 16, 2008 at 10:27:36:
Hi Kevin,
Can I make some suggestions in three areas, regarding this 45 amp schematic?
Hope you take this right, as I do not want to offend.
AUDIO CIRCUIT :
1) Change R6, the "congested" 1K value, to 120 or 121 ohms, nicer !!
2) If you thought it sounded "stressed" at 275 VDC P-K , wait till you try reducing the B+ P-K by 10 VDC more, and ALSO reduce the current by about 20%...(to 28 mA.) and it will sound EVEN LESS STRESSED and sound NICER !!
The globe 45s will last and last also !!
TUBE REGULATORS:
1) I find series regulators are not good enough on their own.
2) On the output of each regulator, add a high quality capacitor, ( GE or ASC OIL, etc.) in the range of 85 to 110 uF. You will restore the low end, and it will be necessary to have this amp play linearly.
( Ha ! You may find you need a real SE output, when you pass some bass through the Eico P-P output )
FILTERING of B+:
1) Whenever possible, eliminate series resistance in the power supply to the finals, especially with DHTs.
You have R4 and R5, 110 ohms and 12,000 ohms of added series resistance, or 12,110 ohms total. It must be avoided through better design. Lets reduce that series resistance by 605-fold. Lets also use a L input filter.
Do this:
L1/C1/L2/C2. Ls are 10 ohm Triad C-40Xs. Cs are 47 to 50 uF, I'd use Panasonic 47 uF /450 VDC caps, ED series. The Ls and Cs are small and inexpensive.
Kevin, at one time or another, I have done all these changes, and I know they will give you the biggest bang for the buck, and work like gangbusters!!
Let me know how it sounds to you, once you hear it.
Jeff Medwin
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Follow Ups
- RE: HF-81... - drlowmu 07/18/0814:41:14 07/18/08 (0)
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