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Re: yell if you want other options... [message #30094 is a reply to message #30093] |
Sun, 09 January 2005 03:56 ![Go to previous message Go to previous message](/forum/theme/AudioRoundTable/images/up.png) ![Go to next message Go to next message](/forum/theme/AudioRoundTable/images/down.png) |
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Wayne Parham
Messages: 18752 Registered: January 2001
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Illuminati (33rd Degree) |
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Hi Douglas, Are you planning to build one of these, by any chance? My plate is pretty full right now, and while I plan to build one, it might be a little while. I'd sure like to see an actual model built and tested. Subjective listening impressions welcome; O-Scope measurements might be cool too. Thanks again for all you've done for this project and for this forum. Wayne
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predictions and more options [message #30095 is a reply to message #30094] |
Sun, 09 January 2005 07:33 ![Go to previous message Go to previous message](/forum/theme/AudioRoundTable/images/up.png) ![Go to next message Go to next message](/forum/theme/AudioRoundTable/images/down.png) |
PakProtector
Messages: 935 Registered: May 2009
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Illuminati (2nd Degree) |
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Hey-Hey!!!, I have built three like it already. The first was SS rectified and had cheap-o coupling caps. It sounded really good. I built two after that with increasing complexity( like you'd expect anything else, right? ).I have another in process which I mentioned as having a schematic in hand for. Just got the big PS choke from Heyboer, and the active load valves from Radio Electric Supply and a bunch of other stuff cleaned up from my slavage box. Top plate on Monday... This gives me a reasonable assurance that it will sound excellent. L-C filter and tube rectifier( either hybrid Graetz-bridge or perhaps get two of the 230V Hammonds and pure valve rectifier...), are definatly an improvement on the all 1N4007 C-R-C-R-C I used at first. One could try the Cree Schottky types. 1A/600V are ~$1 from Tubebuilder in Maryland and are zero recovery time. I tried them in a full bridge amplifier circuit, and found an improvement over Fairchild's Stealth types. The most important modification will be cascoding the active load circuit. One more gate-stopper and one more 2540 and it is done. The 'top' mosfet is the one which will need the heatsink, so leave room to add another, or swap it. If you decide on resistive loads, you'll need a second filter stage. move the big oiler to the output end and put a 450vdc 'lytic in its place. regards, Douglas
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I know you`d like it... [message #30160 is a reply to message #30142] |
Thu, 20 January 2005 15:25 ![Go to previous message Go to previous message](/forum/theme/AudioRoundTable/images/up.png) |
Damir
Messages: 1005 Registered: May 2009
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Illuminati (2nd Degree) |
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Actually, in SE amp (1) I slowly build (long breadbording phase), I use toroidal PTs (2), "ordinary" 5V4G rectifiers (3) CLC filter (4) with MKP first cap, but electrolitic second (5), actually, 2x270uF (6), 130 Ohms 10H choke (7), even add 10 Ohms resistors between the secondary and the rectifier (8), maybe I`ll bypass electrolitics with MKP closer to the 300B (9)... Huh, I really tried, but can`t do 10 Mortal Sins in Audio...sorry. In my defense, I use small 35VA transformer for the heater (6,3V) and filaments (2 x 5V) and separate 300VA transformer with HV 2X360V + 2 x 5V for the rectifiers. Few swithes, and I have standby function like this: main switch on - small trafo is "on" through power resistor (~0,8 Uh on the load), then standby switch "on", and both transformers are "on" - IDH rectifiers provide ~30 sec. more "slow start". In standby, HV is "off" and heaters/filaments are heated with 0,8Uh...
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