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   Home » Melquiades Amplifier » The Milq’s power supplies and rectification. (4 posts, 1 page)
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  »  New  Melequiades PSU..  Re: Do not built LF Melequiades....  Melquiades Amplifier  Forum     8  45370  02-13-2006
  »  New  The single-stage Milq and power Supplies...  Just the tank...  Melquiades Amplifier  Forum     10  53447  05-03-2007
07-13-2007 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,337
Joined on 05-28-2004

Post #: 1
Post ID: 4743
Reply to: 4743
The Milq’s power supplies and rectification.

Since adding the one-staging 3 channels have triggered the replacement of all magnetiks in the Super Milq’s power supplies:

http://www.GoodSoundClub.com/TreeItem.aspx?PostID=3694

http://www.GoodSoundClub.com/TreeItem.aspx?PostID=4708 

I was wondering if I could give a try to the idea that is hanging around my head for quite some time. In my former experiment the debate of SS rectification vs. tube rectification was won by ultra-soft and ultra-fast switching SS rectification with unavoidable following by input choke. The tubes rectification had no bass…. But it is DSET, and my single-stage HF channels will have the bass to begin with… Not to mention that I have in Super Milq individual filters for HF and LF section…

So, I very much am considering this time to implement (or at least to try) for HF channels the rectification around TV dumping diodes. I was looking for 19AU4, that it 175ma half-wave tube. There are also the 12BE3, 17BE3, 6BE3, 6BZ3 but I would like to have more powerful, at least a half amp tubes. Do anyone know any powerful TV dumping diode?

Rgs, Romy the Cat


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
07-14-2007 Post does not mapped to Knowledge Tree
cv
Derby, United Kingdom
Posts 173
Joined on 09-15-2004

Post #: 2
Post ID: 4746
Reply to: 4743
Damper diodes

Hi Romy

6CJ3 (or equivalent) is the one you want. Though I've not used them myself, I have pals who regard them highly, FWIW.

It has an average current rating of 350mA, but don't forget that for a given draw on the supply, the average current through the rectifiers depends on the configuration of the supply. If you use a centre tapped transformer and 2 diodes, with choke input (of course) then you can just about feed a stage drawing 500mA and stay at the spec of 350mA average through the tube.

Did you already order the iron without centre taps? Getting the centre tap well balanced is another matter as well - you want accurate turns count on each half winding and even then, depending on the type of transformer, the DCR on each side may be slightly different so you can equalise this with an external resistor.

Anyway, look forward to hearing how you get on with this and the transformer experiments.

cheers
cv

07-15-2007 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,337
Joined on 05-28-2004

Post #: 3
Post ID: 4753
Reply to: 4746
The rectification experiments, it will be Schottky as well.

Hi Chris.

After much consideration I decided do not make one new toroidal “compromised” transformer that would be able to serve  the needs of my solid-state rectification AND damping diodes at the same time. For solid-state I need 3A/220V but for damping diodes I would need two coils with much higher voltage. It would be possible to do it in one transformer but it would be larger geometrically then I would like it to be. I have ordered the transformers for SS rectification and when (and if) I will try the damping diodes I will have a separate transformer.

For a time being my first step will be substitute my 35ns fast-soft switching FRED diodes with Schottky  on 6C33C's plate – it should be theoretically “better”.

http://www.goodsoundclub.com/pdf/SchottkyBridge.pdf

Sometimes after that I will try the damping diodes… if I found motivations. I do feel that with input chokes, a good SS might do just fine, not to mention the diodes maintaining problems and the needs for an extra soft start… But you never know and I would like do NOT keep the damping diodes trying out of my radars. Anyhow, for a time being I will pick some of those 6CJ3...

Rgs, Romy the cat


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
12-13-2007 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,337
Joined on 05-28-2004

Post #: 4
Post ID: 6116
Reply to: 4753
The death the vacuum tube rectifier?

The switching UHF spikes that were SS rectifiers main “issuers” are gone.  Schottky Diodes with no forward or reserve recovery always did the best but they never were able to care a lot of voltage. The new denegation of Silicon Carbide Diodes are here and they looks like make any theoretical advantage of tube rectification not applicable. 600V, 1200V, 2000V – no problems for Silicon Carbide Diodes.

http://www.infineon.com/dgdl/SDT12S60_Rev.2.2.pdf?folderId=db3a304412b407950112b408e8c90004&fileId=db3a304412b407950112b439db0f6efa

The only problem for Silicon Carbide Diodes is price – they are expensive.

The Digikey sells them for $11:

http://parts.digikey.com/1/parts/419003-schottky-600v-12a-to22022-sdt12s60.html

so the set of diodes for Super Milq would be $264. Sure, it is not end of the world by tangible.

OK, here is the deal. If you during this winter give food for homeless Cats in your neighborhood then you have moral rights to contact Pdasee. Pdasee lives in Wean, Austria and he will sell you the above mentioned diodes for 1 euro each. Pdasee might be contacted at business@vollbio.de

Rgs, Romy the caT


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
Page 1 of 1 (4 items) Select Pages: 
   Target    Threads for related reading   Most recent post in related threads   Forum  Replies   Views   Started 
  »  New  Melequiades PSU..  Re: Do not built LF Melequiades....  Melquiades Amplifier  Forum     8  45370  02-13-2006
  »  New  The single-stage Milq and power Supplies...  Just the tank...  Melquiades Amplifier  Forum     10  53447  05-03-2007
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