I just noticed something when I tried to use cheap no-name spade terminals (probably bought from Aliexpress years ago). They would not take on the solder easily and got all gunked up with burnt up flux yet the solder would not stick. I removed it and used a genuine TE Connectivity AMP Faston brand spade terminal. These are precision made with thick solid copper core and silver plated. They heat up instantly with my soldering iron and the solder wet the part and the pads and flowed nicely. Huge difference. If you notie difficulty soldering the spade tabs, I can highly recommend genuine Faston brand. $0.17ea but well worth it.
62409-1 TE Connectivity | Mouser
CAD drawing showing material composition (copper with silver plating):
https://www.te.com/commerce/Documen...cLang=English&PartCntxt=62409-1&DocFormat=pdf
62409-1 TE Connectivity | Mouser
CAD drawing showing material composition (copper with silver plating):
https://www.te.com/commerce/Documen...cLang=English&PartCntxt=62409-1&DocFormat=pdf
The active bridge is a nice feature that really makes the power from the transformer as noise free as possible. For Class AB amp with high PSRR, the cap multiplier is not really needed.
You may be better off getting a traditional CRC PSU and use an LT4320 active bridge to feed it. Variants of this can be found on Prasi’s thread for LT4320 active bridges.
You could bypass the cap Mx on the SLB and do the same thing if you want. Kind of a waste of capability though.
You may be better off getting a traditional CRC PSU and use an LT4320 active bridge to feed it. Variants of this can be found on Prasi’s thread for LT4320 active bridges.
You could bypass the cap Mx on the SLB and do the same thing if you want. Kind of a waste of capability though.
Huh, you're right. I didn't see prasi's thread there.
What is it about the SLB that negates the need for a separate soft start?
You still need a soft start to prevent current in rush to charge the trafo when you power up. I don’t think I said anywhere that a soft start would not be needed. That’s why we came up with the soft as a feather pillow SFP soft start circuit. It uses SSR’s so nothing to wear out compared to mechanical relays.
Alright, well, if the transformer is not that big I'd be OK with that. Especially since the total capacitance would typically be relatively small due to the cap multiplier.
Yes, sorry about the mixed message - the cap mulitplier provides a softer ramp up voltage to the amp, and in some cases, this slower rise can prevent speaker thump at turn on. However, it doesn't do anything for the surge created by the large transformer in rush current. I will edit post 1 to make that more clear. To really stop turn on thump, the RTR SSR speaker protection with turn on delay is the best way to take care of that.
But surely the 8D-20 in series with the active input to the power traffo does that, V?
Andy
Aah, I didn't know that it reduced the voltage going into the traffo when it had warmed up.
But that's absolutely what I need - as I was getting 22v out from the SLBs when I tested them (without an 8D-20 in place). As my 4R ANs will be driving 3.2 ohm Maggie mid panels and 2 ohm Maggie ribbons - ie. below the nominal 4 ohm spec - I was not keen on upping the DC rails from 20v to 22v.
So it looks like the 8D-20s will do what I need!
Andy
