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51
Amplification (Pre/Power) / Re: How to Build a killer Amp
« Last post by stevenvalve on January 03, 2018, 01:18:43 AM »
I needed less voltage to run the RCA 45 tubes max 250v, instead of 50s max 450v, so i used a .47uf Duelund capacitor instead of a 45uf solen on the output of the rectifier, the voltage went down from 280v to 218v prefect for the 45 valves. The .47 has little affect on increasing the voltage unlike the a 15uf, but still seems to lower the noise floor.
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Amplification (Pre/Power) / Re: How to Build a killer Amp
« Last post by stevenvalve on January 03, 2018, 01:01:10 AM »
Best to run around 300v/0/300v to the rectifier. 400V/0/400v will probably have to much voltage, especially if you run the 15uf cap on the voltage out of the rectifier. The 15 uf cap is needed to lower the noise floor but it is a case of diminishing returns, a bigger cap will probably not lower it much more anyway, but it will not hurt. The other advantage of the 15uf cap is you get a voltage increase and that will allow you to run a lower voltage mains transformer. The UX250 or type 50 is good for 450 volts, but dont run that because that will shorten the life of your hard to find UX250 globes and could make them sound stressed. I run 250v/0/250v and that gives me around 280v-300v at the valve. the B+ switch is used to let the valves warm up before adding the currant, helps the valves last a lot longer. I must say my UX250 globe amplifier running this circuit is so good it is the end game for me, it really does sound real, but to get it there you must use the right bits and tune it correctly. My PX/4 amplifier is running the same circuit and same parts combination.
To help lower the AC filament noise run a 100R resistor from one 6.3v filament wire to ground as seen in the picture
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Announcements / Re: Seasons greetings to all our contributors
« Last post by kajak12 on January 02, 2018, 11:50:36 PM »
merry christmas all from lovely perth
oh and a happy new year
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Other DACs / Re: Marantz cd99 se limited .
« Last post by brenden on January 01, 2018, 01:43:24 PM »
Yep . Same chassis.
   The cd99 se limited  recieved lots of nice refinements trickled down from the cd12  but with the dual differential circuit of  the CD 94 mk2 . The cd99 and the later cd7 were the only machines to recieve the double crowns .
  Some refinements are apparent ,  some are not so apparent .eg a look at the main elna caps  you will notice the thick rubber  vibration /resonance control  on the  top. This was obviously a custom elna cap made  for Marantz . 
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Announcements / Re: Seasons greetings to all our contributors
« Last post by gamve on January 01, 2018, 07:51:38 AM »
Yep. Merry Christmas from sunny Queensland
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Other DACs / Re: Marantz cd99 se limited .
« Last post by stevenvalve on January 01, 2018, 03:20:11 AM »
I have seen wadia 3200, made by Marantz with the copper chassis
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Other DACs / Re: Marantz cd99 se limited .
« Last post by brenden on December 31, 2017, 04:38:13 PM »
Copper plated chassis .
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Other DACs / Marantz cd99 se limited .
« Last post by brenden on December 31, 2017, 01:29:14 PM »
  Comes standard with two   s1 double crowns  in dual differential mode .

    And happy new year to everyone !
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Been looking through my Stash of PX/4 - UX250 - UX245 and there was more, i could not fit them all int this cabinet. Going to sell most of these.
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Announcements / Re: Seasons greetings to all our contributors
« Last post by Jehuty on December 29, 2017, 02:41:18 PM »
Been away for a while, Merry Christmas and Happy New Year all!
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