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Tube DIY Asylum Do It Yourself (DIY) paradise for tube and SET project builders. |
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Tube DIY Asylum Do It Yourself (DIY) paradise for tube and SET project builders. |
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In Reply to: Power amplifier with ONE tube posted by RM on March 10, 2003 at 14:49:13:
Hi,Not to dampen your enthusiasm, but I suspect two 6S45 in parallel will loose a lot of the magic. Low Mu Triodes have enough difference between valves to cause audible problems. With the medium mu and high gm 6S45 the effect will likely be much more pronouced.
How about using two 6S45 in push-pull, but with a little "trick"? What you do is to build the main forward path just like the "Semper Musica", but with a PP OPT of 10k nominal A-A impedance.
In fact, I could think of a few moderatley large (30VA...50VA) torroid mains transformers of the 115V+115V : 6V+6V (or 9V+9V) variety that will show very low leakage inductance. They would hence be suitable to give 12k (6V windings in parralel to 8 Ohm Voice Coil) or 5k (9V windings in parallel to 8 Ohm Voice coil) primary impedances.
Anyway, construct a complete second amplifier path using the second 6S45 and other halve of the primary but drive the grid via either a transformer tap or resistive divider from the previous triode. I think taking the drive to the second 6S45 with a 100 Ohm Pot and some resistors on either side to limit the adjustment from one of the two secondary windings should work okay.
You will need to have actually a small adjustment range in any case to match this, the second "driven" 6S45 should clip slightly before the one in the forward path. Of course, adjsuting the ratio of signal division between the two valves will give a chance to adjust the sound "to taste".
Sayonara
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Follow Ups
- 6S45-PE PSE... - Kuei Yang Wang 04:01:32 03/11/03 (13)
- Re: 6S45-PE PSE... - stelios 07:10:33 03/14/03 (0)
- Re: 6S45-PE PSE... - Brian C. 04:43:37 03/11/03 (11)
- Re: 6S45-PE PSE... - fatbottle 05:44:26 03/12/03 (9)
- Re: 6S45-PE PSE... - Kuei Yang Wang 10:03:15 03/13/03 (4)
- Re: 6S45-PE PSE... - fatbottle 16:24:16 03/13/03 (3)
- Re: 6S45-PE PSE... - Kuei Yang Wang 02:33:48 03/14/03 (2)
- Re: 6S45-PE PSE... - fatbottle 07:29:55 03/14/03 (1)
- Re: 6S45-PE PSE... - Kuei Yang Wang 14:14:10 03/14/03 (0)
- Re: 6S45-PE PSE... - Brian C. 07:26:22 03/12/03 (2)
- Re: 6S45-PE PSE... - fatbottle 08:29:06 03/12/03 (1)
- Woo woo woo, so much to do do do.... - Brian C. 09:54:06 03/12/03 (0)
- Re: 6S45-PE PSE... - fatbottle 06:12:23 03/12/03 (0)
- Me too. Thanks Kuei (nt) - RM 06:52:09 03/11/03 (0)
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