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I feel like I should know this.

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If one included a turn on delay circuit, could you just skip the 5AR4 and use a bridge rectifier or make one with 4 diodes?
Rob C

The world was made for people not cursed with self-awareness

Follow Ups:

RE: I feel like I should know this. - SteveBrown 15:25:20 09/04/13 (1)
Under no circumstances should you install a bridge rectifier - you'll be WAY over voltage. If you switch to SS, you should configure as a full wave rectifier, NOT a bridge (e.g. 2 diodes not 4).
- RE: I feel like I should know this. - Corndog71 10:23:52 09/11/13 (0)
  Thanks. Got it. I should've known that but got confused by the 4 wires going to the rectifier tube. It made me think 4 connections... 4 diodes...
  
  Then I looked over the schematic again and instantly got it.
  
  Rob C
  
  The world was made for people not cursed with self-awareness
RE: I feel like I should know this. - xaudiomanx 17:58:50 08/15/13 (8)
You could use a SS rectifier without a delay circuit if you have caps that can handle the voltage increase or you can use a delay circuit or an inrush limiter but as the voltage comes up it will be higher with SS rectification than with tube by about 40-50 VDC so you still have to make sure the caps can handle the extra voltage.

I happen to like SS rectification in some amp circuits. Most PP amps like the Dynaco stuff is to my liking. I feel tube rectification was used to keep the voltage down but it having a cap right on the rectifier really defeated the purpose.

I also felt the amp sounded better with a 40UF cap on the rectifier then a 100R resistor right off the rectifier with a 40UF cap putting the output tranny B+ right there then the choke with a 40UF cap then leave the rest of the power supply circuit as it was. The amp sounded more lively with an extra stage of decoupling with the output tranny B+ wires before the choke. But that's only my opinion. I got the idea from a good friend and I figured it can't hurt to try it. The circuit then becomes C/R/C/L/C/R/C/R/C power supply. With a SS rectifier you could probably eliminate the choke and cap totally by adding more capacitance on the rectifier(80UF or a little more).
- RE: I feel like I should know this. - Corndog71 11:02:01 08/17/13 (7)
  I probably should've elaborated. I plan to use Clarity TC caps which are 700V film caps. I was thinking C(45uF) L C(110uF) R C(110uF). This is what I did for my ST35 to good effect.
  
  Obviously this will not be in a stock enclosure. I've just had too many issues with tube rectifiers that I would just rather go solid state. Copper Caps are another option but I would almost prefer to avoid the socket connection altogether and keep it internal.
  
  The turn on delay circuit would allow the heaters to warm up before applying high voltage.
  Rob C
  
  The world was made for people not cursed with self-awareness
  - RE: I feel like I should know this. - xaudiomanx 09:40:41 08/18/13 (5)
    Too much UF on the stages after the choke. The TC's(time constants)are affected. Never go more than double the stock amount.
    - RE: I feel like I should know this. - petercapo 14:06:25 08/19/13 (3)
      I would appreciate hearing more about the time constant issue. How does one know when the time constants have been adversely affected, and what exactly constitutes adversely affecting the time constants?
      - RE: I feel like I should know this. - xaudiomanx 05:33:09 08/20/13 (2)
        
        In Reply to: RE: I feel like I should know this. posted by petercapo on August 19, 2013 at 14:06:25
        
        Hi Peter,
        
        I really don't know if it is totally the TC's or just limiting bandwidths to get other bandwidths more pronounced.
        
        The only thing I do know about it is that when you add loads of capacitance to the stages after the choke you create other issues to the sound. That is why when someone says after they do a power supply mod the bass is great and the highs are outstanding, usually it's because they compromised other areas of the bandwith. A good friend and a very qualified tech told me it was the TC's that was inadvertently affected. Maybe another audio hobbyist or tech would call it something different. I know I heard this myself whenever I did a mod using loads of capacitance after the choke. Depending on the type and amount of capacitance used would determine the type of sound I was hearing.
        
        The rectifier, unless it was changed to SS(which lots of them were changed to) usually had 20UF but going to 40UF max was OK but that was the limit before the rectifier went into explosion. Better quality rectifiers could handle a bit more but that's all. SS there was no limit but the turn on was hard.
        
        RE: I feel like I should know this. - petercapo 06:46:48 08/20/13 (1)
        
        In Reply to: RE: I feel like I should know this. posted by xaudiomanx on August 20, 2013 at 05:33:09
        
        Here is some software from Duncan Amps for making calculations on a variety of power supply parameters:
        
        http://www.duncanamps.com/psud2/index.html
        
        Perhaps it could show what the limits are for the amount of capacitance before there is limiting of the frequency response, I don't know. I have downloaded the main software but haven't figured-out how it works yet. I think you might have to download some other files.
        
        Regards,
        Peter
        
        http://www.duncanamps.com/psud2/index.html (Open in New Window)
        
        RE: I feel like I should know this. - xaudiomanx 10:44:51 08/20/13 (0)
        
        In Reply to: RE: I feel like I should know this. posted by petercapo on August 20, 2013 at 06:46:48
        
        Hi Peter,
        
        If you ask Tre' on DIY Tubes he would tell you that the Duncan download for power supplies is only a tool to get you started. I have my friend Danlaudionut draw me a schematic whenever I am going to build something. He uses Duncan to get it going. The rest I do with my ear because at the end of the day what you listen to is all that matters. There are many parameters that go into designing anything, especially audio. Most of the stuff built was done long before Duncan had this download. The Duncan site just makes thing easier to get started.
    - RE: I feel like I should know this. - Corndog71 09:53:23 08/19/13 (0)
      I don't suppose you could elaborate on this a bit? Does it matter that the TC caps have very low ESR? 45uF-1.4 mili-ohms, 110uF-1.6 mili-ohms
      
      I guess I could just use the 45uF caps. That'll save a few bucks.
      Rob C
      
      The world was made for people not cursed with self-awareness
  - RE: I feel like I should know this. - xaudiomanx 09:36:33 08/18/13 (0)
    You could also install a simple rail switch but you have to manually turn it on and off. The less you put in the less can break.
    
    If you are having trouble with tube rectifiers it could be that you have too much capacitance right on the rectifier or you are using cheap rectifiers.
RE: I feel like I should know this. - petercapo 17:55:19 08/15/13 (1)
I am assuming that whichever time delay you are thinking of warms up the filaments before applying B+. Delaying application of B+ is one thing, while easing current inrush is something else � the one does not necessarily imply the other. You would lose the slower turn-on of the 5AR4 unless the delay board has inrush limiting built-in.
Left by themselves, solid state diodes will not have nearly the voltage drop of a 5AR4, which could easily overstress the power supply and other parts of the amp.
So if you want to use a time delay and solid state diodes, you might consider doing something to compensate for these issues.

Edits: 08/15/13 08/15/13 08/16/13
- RE: I feel like I should know this. - xaudiomanx 18:06:12 08/15/13 (0)
  That is why I suggested going to a higher voltage handling cap. One of the mods I did was an out board cap bank on a separate chassis to allow me to make the caps to whatever voltage and capacitance I needed. I tied the cap bank to the main amp chassis power supply with a heavy duty power cord consisting of 4 conductor wires.
  
  Another good mod which made a huge difference sonically was going to an all metal film power supply or motor run caps on a separate chassis in place of the electrolytic cap(s). I left the original can cap in for appearance but it wasn't used in the power supply at all.

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