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 NEW  Matt presents bias and operation data for the 6V6 tube in SE operation - 6V6 Single-Ended (SE) Ultra Linear (UL) Bias Optimization.

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PostPosted: 12 Jul 2011, 01:37 
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Joined: 28 Jan 2011, 11:51
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Use a NOS rectifier for best sound . Try hunting down a few 5Z3 (5U4G on UX4 base) . Cheaper than a modern production 5U4G and no doubt better sounding

BDA


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PostPosted: 06 Feb 2012, 18:57 
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Matt was kind enough to put together an article about Power Supply Design for Vacuum Tube Amplifiers and we have added it to the site.

http://diyaudioprojects.com/Technical/T ... -Supplies/

Cheers

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PostPosted: 06 Feb 2012, 22:07 
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Location: Chilliwack, BC
Awesome!

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PostPosted: 08 Feb 2012, 12:54 
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Joined: 30 Apr 2011, 11:13
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Location: Malta
I recently tested a couple of 866a and one of them is fully "silvered" when cold and even when warm and working for about 30min with a load it still does not clear

That said it works perfectly and has a drop down voltage aprox 3v lower than the others i tested.

Could it be that it just has alot of mercury or is it some thing i should worry about


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 Post subject: Re: MV Tube Rectifiers
PostPosted: 20 Feb 2012, 00:06 
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Joined: 19 Feb 2012, 23:32
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I don't see any issues with MV rectifiers if placed in a circuit properly.
I personally love their menacing blue flicker in the dark :)

I'm about to embark on a quite large build, but my first priority is the power supply before anything else!
The power supply will be separated from the mono blocks ( weight issues ) as there will be a lot of iron on top of that box...
2 x 600V 2A transformers tapped every 50V plus the heater transformers for the bias and heater transformers for the HV plus the Giant PIO caps and the Two 5-10H chokes.
Expecting power supply to be in the 60+ pound range!
The main reason for that is that my HV rectifiers will be FOUR 866AX NOS tubes i picked up from a local guy :)
the bias supply will be FOUR 5U4GB to feed the power hungry KT88 ( KT120 latter ) Quartet on each mono block.


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PostPosted: 20 Feb 2012, 10:36 
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Joined: 04 Jun 2008, 20:59
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Location: Arizona, USA
Hi Matt, Great write up. :thumbsup: For lots of reasons, I use fast SS rectifiers in my projects, but tubes certainly could work. This is particularly true as they are class A amps and the required B+ current is both known and consistent.

Good listening
Bruce

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PostPosted: 21 Feb 2012, 03:08 
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Joined: 19 Feb 2012, 23:32
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Whats the absolute maximum ratings for the 5U4 ?

The 866A's broke in transit from the north end... He wasn't happy that he was out $350, but i do have to call him a dill hole as he just laid them in a box with nothing in between them and tossed them into the trunk :/


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PostPosted: 21 Feb 2012, 13:38 
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Location: US Pacific Northwest
5U4GB Ratings:

PIV: 1500V
Steady State Peak Plate Current: 1000mA
Tranisent Peak Plate Current 4.6A

For other ratings see the GE Data sheet: http://tubedata.milbert.com/sheets/093/5/5U4GB.pdf

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PostPosted: 21 Feb 2012, 16:36 
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Joined: 14 Feb 2010, 13:13
Posts: 663
Location: Lisbon, Portugal
Matt,

Do you have a pdf from your great PSU tutorial? :)


Cheers!

Miguel


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PostPosted: 21 Feb 2012, 21:17 
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HT Performance wrote:
Do you have a pdf from your great PSU tutorial?
Yes I do. I'll send you a message.

Gio; What are the chances of posting the PDf as a downloadable file? :lightbuilb:

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