• Re: The new 845 and 300B+ - Rasim 01:35:35 03/30/05 (0)
  In Reply to: The new 845 and 300B+ posted by bcherry on March 17, 2005 at 19:02:24:

  Brian,

  What do we need to modify if we decide to use this 300B+ on LD+? How much power can we get with the OPT LD+ has?

  Thanks,
  Rasim
  
  

  ---
• Re: The new 845 and 300B+ - J. Mikell 17:58:28 03/20/05 (3)
  In Reply to: The new 845 and 300B+ posted by bcherry on March 17, 2005 at 19:02:24:

  Why is the 845 smaller than the 300b? seems kind of off...
  On another subject, will the valve art 845B ever be back? and if so, do you plan to carry the metal plate version as well?
  Thanks,
  Mikell
  
  

  ---

  • Re: The new 845 and 300B+ - bcherry 15:36:43 03/21/05 (0)
    In Reply to: Re: The new 845 and 300B+ posted by J. Mikell on March 2, 2005 at 17:58:28:

    845b and 845m: Sure they be back when when they fix them.

    The 300b+ can comfortably put out 20watts into 1k5. So the plate needs to be big. But filament current draw is at least 2x 300b.

    The 845 even though a bit smaller puts out +2w over the standard 845 spec.

    Brian
    
    Take control! DIY.
    
    

    ---
  • Re: The new 845 and 300B+ - McAllan 10:46:03 03/21/05 (1)
    In Reply to: Re: The new 845 and 300B+ posted by J. Mikell on March 2, 2005 at 17:58:28:

    Because it's a 300B+ and not an ordinary 300B.
    300B+ is longer. How it else differs from the ordinary 300B I can't tell but I remember reading somewhere they without problem can be used instead of an ordinary 300B. But if desired it can pull more power than the ordinary version.
    Hope someone can confirm this.

    -Morten
    
    

    ---

    • Re: The new 845 and 300B+ - zarniwoop 15:19:48 03/21/05 (0)
      In Reply to: Re: The new 845 and 300B+ posted by McAllan on March 21, 2005 at 10:46:03:

      Jeez, that plate is huge.. must be good for 75W dissipation... if the rest of the internals can cope with that.

      seems like a waste to put it into a stock 300B circuit, loafing along at 400V, 75ma or somesuch. The WE can output 16W at max ratings. This should readily give 20-25W... if you design around it specfically.
      
      

      ---
• The new 300B+ 1st cut... - Thorsten 13:36:17 03/18/05 (2)
  In Reply to: The new 845 and 300B+ posted by bcherry on March 17, 2005 at 19:02:24:

  Hi,

  The first thing I did was to hook up the 300B+ to my lab PSU and test Brians remark of 3.6A heater current had me scared.

  Well, alarm bells off, both draw a short peak of 3A+ on switchon but settle at < 2.4A, the LD+ Heater supply is designed to cope with that.

  Okay, I happen to know that Master Liu runs the 300B+ "low & Hot", that is loads of current, low anode voltage, low load, sorta 350V/160mA/1K5.

  So, just to be perverse I'll try the opposite, namely 450V/120mA/2K5. This according to P-Spice simulations with a VERY ROUGH model for the 300B+ (Brian, do you have Sofia curves for the 300B+?) should allow 20W+ for 5% THD limit.

  The 310A from the 91 Frontend looks servicable if we crank up the Anode Voltage to 250V with 135V screengrid voltage (slight change in cathode R).

  If I find the time this WE I'll give this whirl.

  Ciao T
  
  

  ---

  • Re: The new 300B+ 1st cut... - bcherry 01:12:36 03/22/05 (1)
    In Reply to: The new 300B+ 1st cut... posted by Thorsten on March 18, 2005 at 13:36:17:

    Maybe some variation with the filaments then as Liu confirmed he was getting 3.6 current draw with his.
    Liu has it set up to run 120ma/400v/1k5 with the big cores.

    No curves for the new 300B+ yet. In fact no Sofia anymore as replaced it with an Amplitron. Will do some curves soon as I get some pending issues out of the way.

    Will be neat if you can implement the 310a. We're really in a groove with this tube.

    Brian

    
    Take control! DIY.
    
    

    ---

    • Re: The new 300B+ 1st cut... - Thorsten 01:18:39 03/22/05 (0)
      In Reply to: Re: The new 300B+ 1st cut... posted by bcherry on March 22, 2005 at 01:12:36:

      Hi,

      > Maybe some variation with the filaments then as Liu confirmed
      > he was getting 3.6 current draw with his.

      Hmmm. They PEAKED at 3.6A, but dropped to 2.4A once the heaters had stabilised....

      > Liu has it set up to run 120ma/400v/1k5 with the big cores.

      Well, I have decided on 120mA/450V/3k myself and to accept that at really low frequencies the OPT will saturate.

      > No curves for the new 300B+ yet. In fact no Sofia anymore as
      > replaced it with an Amplitron. Will do some curves soon as I get
      > some pending issues out of the way.

      Thanks. I used the curves from old 300B+ Datasheet, not sure how close this matches.

      > Will be neat if you can implement the 310a. We're really in a
      > groove with this tube.

      Looks like we need a little bit more swing into a little bit more capacitance than the 310A is happy with.

      See my new post up there:

      http://www.audioasylum.com/forums/DIYHiFi/messages/4943.html

      for my current ideas.

      I'm butchering a dreadfully build Amp from Dared for the chassis, driver 76 & 5687.....

      Ciao T
      
      

      ---
• wow, interesting! - Ed Sawyer 19:37:52 03/17/05 (4)
  In Reply to: The new 845 and 300B+ posted by bcherry on March 17, 2005 at 19:02:24:

  is the 845 Thoriated-tungsten filaments? that 300b looks almost garish it's so LARGE and LONG. Daaaaamn. I'd think they would forego the ST_shape bottle, it's kinda useless @ that point. A big globe or straight-sided tube would look better IMHO. Dissipation must be enormous with a plate that big. Talk about long unsupported filaments - wow! Cool stuff, no doubt.

  -Ed
  
  

  ---

  • Re: wow, interesting! - bcherry 15:31:19 03/21/05 (1)
    In Reply to: wow, interesting! posted by Ed Sawyer on March 17, 2005 at 19:37:52:

    Ed
    No thoriated filament.

    Brian
    
    Take control! DIY.
    
    

    ---

    • hmm. the plot thickens - Ed Sawyer 19:33:28 03/22/05 (0)
      In Reply to: Re: wow, interesting! posted by bcherry on March 21, 2005 at 15:31:19:

      So, that will be somewhat unique: oxide fils on a graphite plate 845-oid... no one else makes them quite like that. Any idea on pricing? In general I am not convinced oxide fils are a good thing on 845 tubes...

      will it draw 10v/3.25A for fils? The Kron (the only other oxide 845) doesn't, IIRC....

      -Ed
      
      

      ---
  • For Brian - jojomau 05:31:27 03/18/05 (1)
    In Reply to: wow, interesting! posted by Ed Sawyer on March 17, 2005 at 19:37:52:

    Have the new 300Bs been installed for demo in your Mongkok showroom?
    
    

    ---

    • Re: For Brian - bcherry 15:30:06 03/21/05 (0)
      In Reply to: For Brian posted by jojomau on March 18, 2005 at 05:31:27:

      Not yet but a built up set is on its way. Will post some pics when it gets here.
      Brian
      
      Take control! DIY.
      
      

      ---

This post is made possible by the generous support of people like you and our sponsors:

Sonic Craft

---

[ Top of Page ] [ Contact Us ] [ Support/Wish List ] [ Copyright © 2025, Audio Asylum, all rights reserved ]

---

[ General ] [ Speakers ] [ Tubes ] [ Vinyl ] [ Digital ] [ Hi-Rez ] [ Video Asylum ] [ Cables ] [ Tweaks/DIY ] [ Music ] [ Films ]

---