Forgot to answer your question...
DIY aficionado here but I think if the caps remain charged the lack of soft start will be more bearable. Anyway, I never use them in my tube amps.
Just a few more comments before the BIG
D) premiere.... I'm a tube guy, this amp is gonna "compete" against a push pull amp that took me several years to perfect. This mofo is even hotter so not good for this period of the year here in Spain.
DIY aficionado here but I think if the caps remain charged the lack of soft start will be more bearable. Anyway, I never use them in my tube amps.
Just a few more comments before the BIG
D) premiere.... I'm a tube guy, this amp is gonna "compete" against a push pull amp that took me several years to perfect. This mofo is even hotter so not good for this period of the year here in Spain.
But......capacitors are capacitors....they are not batteries.
Yes. Capacitors will discharge due to designed (and leakage) paths typically within seconds/minutes after mains power is cut to the power supply.
Yes. As such, there will be an initial power surge when mains voltage is once again applied to the power supply.
Not as critical in vacuum tube amps, especially with vacuum tube rectifiers in them.
Yes. Capacitors will discharge due to designed (and leakage) paths typically within seconds/minutes after mains power is cut to the power supply.
Yes. As such, there will be an initial power surge when mains voltage is once again applied to the power supply.
Not as critical in vacuum tube amps, especially with vacuum tube rectifiers in them.
You say with "each transformer leg"--but you only have ONE primary transformer winding according to the schematic you provided. True? In-rush limiters typically go on the mains winding, so you would only need one--but it must be compatible with your 240v mains voltage.
As Can Am Man say it may take minutes or hours
Thing is the charge there can be preaty nasty and give you a bit of a shock
maybe even the day after as Jaco say what that charge would be?
Normaly Enoug to melt a tip of a screw driver as Murphy Laws aplly
Is it worth the risk for a few pence a resistor cost?
About inrush limiters I hate the things and once the caps are charged I bipass mine with a relay
They are necessary evil that alowd for a smaler fuse to be used again a question of safety.
Question what size of caps you use on the Valve amplifiers 10000 uF ?
On the F5 I have only 200000 uF at the moment so IMO both bleaders and Inrush limiters make sense to me.
Maind you you are more than free to do as you please.
I supose You have no Partner or Kids listening to music while you are not there?
Other thing that came to mind is that normaly you have an output transformer on the Valve amps so DC on speakers is not realy a problem.Is it?
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Bleeders: People bother with bleeders, because they discharge the capacitors more quickly (and more thoroughly, and more consistantly) than relying upon the leakage and circuit design to do it. Look at it this way: bleeders are a cheap insurance policy, for both DIYer's and manufacturers alike.
Either side: I'm not familiar with your national electrical codes, but perhaps someone else could advise. I'm thinking either side would be OK, but I'm just a guy who plays with 120 VAC and US electrical codes.
It doesn't take minutes. It can take days. I have measured 80% B+ voltage still stored on caps after not using the amp for a few days. It depends on several factors which escape my comprehension. Because I have observed that other caps in similar circuits only retain 20% B+ voltage after a few hours. Must be the leakage paths being too wide in some and too thin in others.
I have built some tube amps for friends and they had a bleeder resistor. The B+ in my amps is around 300 volts. I choose not to use bleeders. I generally switch off the amp while the music is still playing. Doing so the caps get discharged and I also learn something about caps and circuit behavior. In some circuits distortion comes right away after switching off, others take several seconds with no apparent distortion. Music dies off sweetly. Also, I have identified caps with problems doing this. Having said that, I appreciate your advice and the info given about where to place the inrush limiter.
I have built some tube amps for friends and they had a bleeder resistor. The B+ in my amps is around 300 volts. I choose not to use bleeders. I generally switch off the amp while the music is still playing. Doing so the caps get discharged and I also learn something about caps and circuit behavior. In some circuits distortion comes right away after switching off, others take several seconds with no apparent distortion. Music dies off sweetly. Also, I have identified caps with problems doing this. Having said that, I appreciate your advice and the info given about where to place the inrush limiter.
There is something about your two statements, above, that I find unsettling. Best of luck with your designs then, Cassiel.
You forgetting JFETs are normally open ?
Check out drain current in the J74/K170 datasheets for Vgs=0 and Vds=0
(aka thing bleeds itself)
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Some people find unsettling watching bike racing or watching a horror movie. I don't. As for the luck factor I just hope not to turn into a sleepwalker one night, open up my amp's chassis and stick my fingers where it hurts. BTW, the real scary thing is measuring voltages on live circuits operating with lethal voltages and I'm talking about 800 VDC not 25. I know the feeling of high current flowing through your chest. Not very nice but interesting nonetheless.
OK
As I said you are free to do as you please.
Especialy as there is litle risk to others in your case.
And I can only agree with you the trill of same current flowing troug your chest may have it's apeal.
Ac may shake you up a bit and it is suprising how far you can trow sometink when it bite
DC is a bit less trilling as whatever you hold you just grip harder and you do not let go
And by the way is not the Voltagge that send you to bog is the current.
As you mention Bike racing do those riders go around the track in their kegs and hair blowing in the wind?
There is no need to turn in to sleep walkers to open up the case and stick things in the wrong place we all do that sooner or later.
As I mentioned if sometink can go wrong it will does realy mather how much wrong it can be?
IMO a few pence to reduce the risk is quite sensible thing to do.
DC on the speakers annoys me as well it is also quite boring as speaker go thump once and then no more.
As I said you are free to do as you please.
Especialy as there is litle risk to others in your case.
And I can only agree with you the trill of same current flowing troug your chest may have it's apeal.
Ac may shake you up a bit and it is suprising how far you can trow sometink when it bite
DC is a bit less trilling as whatever you hold you just grip harder and you do not let go
And by the way is not the Voltagge that send you to bog is the current.
As you mention Bike racing do those riders go around the track in their kegs and hair blowing in the wind?
There is no need to turn in to sleep walkers to open up the case and stick things in the wrong place we all do that sooner or later.
As I mentioned if sometink can go wrong it will does realy mather how much wrong it can be?
IMO a few pence to reduce the risk is quite sensible thing to do.
DC on the speakers annoys me as well it is also quite boring as speaker go thump once and then no more.
All things are relative.
By the (short) time the bias of the outputs cuts off, the charge of the F5 power supply capacitor bank has reduced to ~10% of the max value.
The 2K2 bleeder resistors, as in the PS schematic at post 1, are of higher value than the resistance to 0V/ground in the amp itself.
The bleeder R's only shorten the discharge time by a quarter or so.
By the (short) time the bias of the outputs cuts off, the charge of the F5 power supply capacitor bank has reduced to ~10% of the max value.
The 2K2 bleeder resistors, as in the PS schematic at post 1, are of higher value than the resistance to 0V/ground in the amp itself.
The bleeder R's only shorten the discharge time by a quarter or so.
I think I need a bias lesson again.
I've replaced my feedback transistors that were in backwards, and a mosfet, etc...
Anyways, I've adjusted P1 and P2 counter-clockwise until I hear the clicks.
I get .000v across R12 and ~ .35v across R11 when I power it up, my offset is way off.
I started adjusting P1 & P2, and got some reading, but was scared because I was up around 1.5v for one of my reading... I turned it off and reset the pots back to "0" hopefully.
Hmm, should I give it another go? I thought I should be getting .000v across R11 & R12 when the pots are at "0" ?
Any suggestions?
I've replaced my feedback transistors that were in backwards, and a mosfet, etc...
Anyways, I've adjusted P1 and P2 counter-clockwise until I hear the clicks.
I get .000v across R12 and ~ .35v across R11 when I power it up, my offset is way off.
I started adjusting P1 & P2, and got some reading, but was scared because I was up around 1.5v for one of my reading... I turned it off and reset the pots back to "0" hopefully.
Hmm, should I give it another go? I thought I should be getting .000v across R11 & R12 when the pots are at "0" ?
Any suggestions?