I just stick the relay coil across the supplies, the contacts short a resistor in series with the primary of the main power transformer(s). Size determined by inrush current. Your time constant is part of one second.
KISS, keep it simple ... stupid. Don't overcomplicate things. The purpose it to reduce inrush current to reasonable levels. Nothing more. Once you have built up supply voltage, the inrush has fallen to reasonable levels. If you want, you can use a simple timer circuit, but why? Use a power supply you already have if you want to time the relay closing, the filtered DC for the rails will work. An R-C for time constant to a single transistor circuit works.
Protection disconnects the outputs from the load (speaker), that is a different function.
As far as specifics, in order to help you, attach the schematic. Then no one has to guess and you get a good answer.
KISS, keep it simple ... stupid. Don't overcomplicate things. The purpose it to reduce inrush current to reasonable levels. Nothing more. Once you have built up supply voltage, the inrush has fallen to reasonable levels. If you want, you can use a simple timer circuit, but why? Use a power supply you already have if you want to time the relay closing, the filtered DC for the rails will work. An R-C for time constant to a single transistor circuit works.
Protection disconnects the outputs from the load (speaker), that is a different function.
As far as specifics, in order to help you, attach the schematic. Then no one has to guess and you get a good answer.
Unfortunately I don't have a schematic, but I did post the PCB layout and the components of the soft start in question (one cap and two ICLs) a few posts above.
I'm asking because I got a hint from a person off the forum that I should check if that soft start will work with the Wolverine, as that soft start was designed for a class A amp and Wolverine is class AB... Someone already mentioned that class of the amp doesn't matter in this case so I think we are good here.
Thank you for your help!
EDIT: here is what I was told and why I'm checking
I'm asking because I got a hint from a person off the forum that I should check if that soft start will work with the Wolverine, as that soft start was designed for a class A amp and Wolverine is class AB... Someone already mentioned that class of the amp doesn't matter in this case so I think we are good here.
Thank you for your help!
EDIT: here is what I was told and why I'm checking
Ignore circuits and boards without schematics.
Boards can be multi-layer. It takes time to figure out a circuit from the PCB and you still could be surprised at how someone decided to do things. It's fair to ask when you have a diagram. It isn't fair to ask people to try and figure things out from a PCB layout or picture. We can make a guess - but it is a guess only.
I said it doesn't matter what class or type the amplifier (or whatever is). You only need to know how much current and maybe what the expected surge current is. Break things down so they are simple.
Boards can be multi-layer. It takes time to figure out a circuit from the PCB and you still could be surprised at how someone decided to do things. It's fair to ask when you have a diagram. It isn't fair to ask people to try and figure things out from a PCB layout or picture. We can make a guess - but it is a guess only.
I said it doesn't matter what class or type the amplifier (or whatever is). You only need to know how much current and maybe what the expected surge current is. Break things down so they are simple.
Rhthatcher provides full documentation including schematics for all his projects.
That said, I would not use that CL60 board with Wolverine. The current drawn will vary greatly depending on speakers used and the twist of the volume knob, this will change the resistance of the 5A CL60 during operation because it's always in the circuit, never bypassed.
The Hypex board that Mainframe suggested works wonderfully. The added features are very handy also, the ability to use a low voltage momentary pushbutton switch eliminates the need to run mains voltage to a front panel power switch.
There ya go. For class AB amps, it sounds like it's better to bypass the thermister after initial power up to avoid the effects of the thermister after initial inrush current has passed (this requires some sort of delayed switching device, like a timed relay). Thank you @Vunce!
Yup, it is assumed that you would short out the loss element once the surge was over. Even tube amplifiers suffer from "bouncy" power if you leave an NTC resistor in series.
The use of a single NTC resistor is best left to devices with constant current draw, and not all class "A" amplifiers have constant current draw either.
The use of a single NTC resistor is best left to devices with constant current draw, and not all class "A" amplifiers have constant current draw either.
Fantastic! That is exactly what I was suggested to double check before going forward with the CL60, and it was well worth it. Thank you so much!
Definitely going with the @Mainframe suggestion. Much appreciated!
@Mainframe
For the dual mono build I'm going for, I guess I need to go with two soft start modules? Just checking before placing the order... Thanks!
For the dual mono build I'm going for, I guess I need to go with two soft start modules? Just checking before placing the order... Thanks!
Thank you!
Would it be better to have dedicated board per transformer, so it can independently handle the inrush per transformer channel, if for some odd reason inrush current behaves differently per channel?
For example, left channel still needs slower rampup as it's not completed the power-on, but right channel already completed initial power-on and the circuit has been bypassed even though the left channel still needs slower ramp up? Or maybe some other reason I'm not aware about...
Again, I'm beginer and trying to logically deduct and conclude what are the potential pitfalls I'm trying to avoid...
Then In case of two boards, power on switch would be connected to both boards simultaniously, but the inrush current would be handled individually per channel.
Would it be better to have dedicated board per transformer, so it can independently handle the inrush per transformer channel, if for some odd reason inrush current behaves differently per channel?
For example, left channel still needs slower rampup as it's not completed the power-on, but right channel already completed initial power-on and the circuit has been bypassed even though the left channel still needs slower ramp up? Or maybe some other reason I'm not aware about...
Again, I'm beginer and trying to logically deduct and conclude what are the potential pitfalls I'm trying to avoid...
Then In case of two boards, power on switch would be connected to both boards simultaniously, but the inrush current would be handled individually per channel.
Well, think about it. What is the purpose of inrush current limiting? Does it matter exactly how much? It doesn't - within reason. What you are really trying to do is limit inrush current through the power switch, and the initial charging current in your main filter capacitors. This extends their life quite a bit. This is the only reason (unless the momentary dimming of your lights is important).
So one board sized for both will do just fine. If for some reason you wanted to control each independently (like powering up and down one channel independently of the other), that is another question.
There are things in electronics where a range is fine, others where exact values are more important. This is one of those approximate range things.
So one board sized for both will do just fine. If for some reason you wanted to control each independently (like powering up and down one channel independently of the other), that is another question.
There are things in electronics where a range is fine, others where exact values are more important. This is one of those approximate range things.
Oh I see, I was picturing it wrong the whole time. Soft start sits between mains and transformers, not between transformers and cap bank.
Then I just hook up mains to soft start input, and two transformers primaries to soft start output (in parallel). Then the rest of the PSU circuit comes...
And I went through soft start pdf three time already lol. 😳
My apologies for the confusion and many thanks for all the info given! Ordering one now.
Then I just hook up mains to soft start input, and two transformers primaries to soft start output (in parallel). Then the rest of the PSU circuit comes...
And I went through soft start pdf three time already lol. 😳
My apologies for the confusion and many thanks for all the info given! Ordering one now.
Grab your WIMA MKS 's now if you want em, they've been EOL'd.
https://www.diyaudio.com/community/threads/wima-mks-and-more-caps-discontinued-eol.425402/
Wolverine has a couple listed in the BOM, but not without alternatives so no major panic.
https://www.diyaudio.com/community/threads/wima-mks-and-more-caps-discontinued-eol.425402/
Wolverine has a couple listed in the BOM, but not without alternatives so no major panic.
A list would be helpful.
Normal electrolytic capacitors are fine for coupling duties. I use those where leakage is an issue, or if there will be signal voltage across the capacitor.
Normal electrolytic capacitors are fine for coupling duties. I use those where leakage is an issue, or if there will be signal voltage across the capacitor.
63VDC 1uF - 5mm LS - for both locations so 4x for stereo set.
MKS2-1/63/10A is listed as one of the many options
I see alternatives from Vishay, KEMET, TDK... but I know people have their favorites 🙂
MKS2-1/63/10A is listed as one of the many options
I see alternatives from Vishay, KEMET, TDK... but I know people have their favorites 🙂
Stereo amp, dual mono PSU
2 x Precision V5 EF3-3 Boards + 2 IPS Boards
1x set of EF3-3 heatsinks (comes with the 6 heatsinks you'll need)
8x pairs of 3503/1381's
Supporting boards (optional)
2x dual rectifier boards
1x speaker protect (comes as pair)
2x ground lift
2x T-ground (you can get away with a standard small earth bar or similar terminal block here if you prefer because of the dual mono, more of a shared PSU thing due to the left and right channels sharing the same PSU 0V source)
Take your time, theres no rush. You need to make sure you can fit everything in the chassis too. (I'm just thinking 2x transformers and all these boards in a 300mm deep chassis might be a squeeze!!)
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As for that PSU board, it will work fine. Those traces may be on the light side, if not 2oz copper? Cant tell from description. I've only used CC supplies with class AB. That said, not hard to remove resistors and install jumpers to turn any CRC board into a CC board should you wish.
Prasi's board HERE has much better trace size & layout IMO, and can be used as CRC or CC. You would need two boards, mind.
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