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In Reply to: RE: Eric Barbour's Brute force regulator mods posted by amnesiac on February 24, 2015 at 08:04:55
If you would be interested in a shunt regulated supply instead of series regulation and are not SS phobic K&K Audio sells a kit that consists of a CCS and shunt reg. on one board. I did the beta testing for this and use it for the input and driver stages of my mono-blocks (122V & 434V). If you are using it with a single-ended stage the shunt current should approximately equal the current draw of the circuit so the heat sink on the shunt devise should be appropriately sized. The CCS needs to see ~50V across it, so dropping the raw voltage down to 350V with RC filter first is a very good idea. Shunt reg. the input and driver stages of my amps greatly improved their sonic presentation.
"It is better to remain silent and thought a fool, then speak and remove all doubt." A. Lincoln
Follow Ups:
So can I set these and they will stay set for ten years? This amp will be so heavy I don't want to remove it much once it installed.
I have 4 salas regs that will not likely be built. I am concerned if I have the ability to see if they are unconditionally stable and if they will stay that way.
Are the K&K regs easier then salas regs? I thought the salas had a ccs too? how long have you had them running in your amp?
I've had the regs in my amps, line stage and phono pre for over two years. There are some considerations you need to be aware of if you decide to install. If the heat sink the shunt FET is mounted on is not able to safely dissipate all the heat generated with zero load (all current from CCS is shunted) it will fail. So, no operating the PS without tubes. If a tube fails, ditto. Kevin's version of the Salas reg. uses a small reference CCS (~1mA) in series with a resistor to derive the reference voltage. The version that he sells with the kit uses a JFET as a 2 terminal CCS and a trim pot so that the reg. voltage is adjustable. There is a temperature coefficient at play here. The adjustment needs to be done when the amp has reached thermal equilibrium. At start up the voltage will be lower and then rise to the reg. setting. The driver stage of my amp with a reg. voltage of ~430V had a +- 20V swing with a 20 degree change of ambient temperature (60-90degrees). That said, the regulators that I am now using have a more sophisticated zero tempco cascode reference CCS and a fixed resistor. They come up to voltage within 30s and stay put. Kevin doesn't sell them this way because he believes DIYers want the adjustability and he doesn't want to stock a bazillion Rset resistors. Unless you have direct coupled stages where tight control of voltage is crucial, having the voltage drift a little probably is not a big deal. I did have a reg. fail on the input stage of my power amp once when a tube went whockey (small heat sink). It was easy to fix. Hope this helps you decision. I do have 11 of these throughout my system. Adding them improved sound staging, front to back separation, back ground silence and speech intelligibility. Adding them to the driver stage of my power amps noticeably improved bass definition.
"It is better to remain silent and thought a fool, then speak and remove all doubt." A. Lincoln
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