3R will give essentially the same outcome as 3R3.
Another thing, mod thing:
We post sale stuff only in swap meet and we don't repeat in technical threads. There is a rule for not posting your thread or subject in more than one forum. Rule 14.
http://www.diyaudio.com/forums/site-announcements/167561-diyaudio-rules.html
Another thing, mod thing:
We post sale stuff only in swap meet and we don't repeat in technical threads. There is a rule for not posting your thread or subject in more than one forum. Rule 14.
http://www.diyaudio.com/forums/site-announcements/167561-diyaudio-rules.html
They can take the heat, but start to reduce current as they go above temps. Fire them up and just check. Five seconds on heatsink and your good. Less and you getting hot.
OK that's the 3R0 series resistors fitted.
Heatsinks only reached 35 Degrees after 10 mins so time to give them a longer warming up period.
Heatsinks only reached 35 Degrees after 10 mins so time to give them a longer warming up period.
They're up to 53 Degrees now but there is no lid on the box.
I've just put lid on and its crept up to 56 Degrees and still climbing.
I might just need to go to 6 Ohms ~ 250mA
60 Degrees and still climbing. It's winter here, that's not going to do the Obligatos any good.
I'm going to opt for cooler running and put the 10Rs back in.
I've just put lid on and its crept up to 56 Degrees and still climbing.
I might just need to go to 6 Ohms ~ 250mA
60 Degrees and still climbing. It's winter here, that's not going to do the Obligatos any good.
I'm going to opt for cooler running and put the 10Rs back in.
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hi, it was normal for a long time, suddenly some problem on positive side
the resistor at 2x68r is so hot that cannot be touch,
the 3 leds is so dim,
but the output voltage was normal at +10.3v / -10.6v
what is wrong?
the resistor at 2x68r is so hot that cannot be touch,
the 3 leds is so dim,
but the output voltage was normal at +10.3v / -10.6v
what is wrong?
the [input voltage - output voltage] is too low.
and/or
the load is pulling more current than the CCS is set to provide.
and/or
the load is pulling more current than the CCS is set to provide.
DCB1 buffer with Tube Power Amp?
[ would only expect a Mosfet to fail if anything would ever fail. I have a shunt like that but at 230mA on for 6 months now 24/7, no problem yet. If you use 68R//68R=R1=34R and your LEDs are 1.8V Vf then just 60mA will run. I would not be afraid of 0.43W on the shunt TO-240 Mosfet. You can use rudimentary sinks on all Mosfets if in a hot environment and always on. If your amp has an input capacitor, then there is no problem anyway even if one rail fails and DC appears on B1's output. Actually, a non capacitor coupled B1 is NOT recommended for driving amplifiers that lack input capacitor or DC protection. This is a disclaimer]
Does the above disclaimer in post #46 by Salas apply to a tube power amp without input caps and DC protection, but which of course has output transformers presumably protecting the speakers? Thanks.
[ would only expect a Mosfet to fail if anything would ever fail. I have a shunt like that but at 230mA on for 6 months now 24/7, no problem yet. If you use 68R//68R=R1=34R and your LEDs are 1.8V Vf then just 60mA will run. I would not be afraid of 0.43W on the shunt TO-240 Mosfet. You can use rudimentary sinks on all Mosfets if in a hot environment and always on. If your amp has an input capacitor, then there is no problem anyway even if one rail fails and DC appears on B1's output. Actually, a non capacitor coupled B1 is NOT recommended for driving amplifiers that lack input capacitor or DC protection. This is a disclaimer]
Does the above disclaimer in post #46 by Salas apply to a tube power amp without input caps and DC protection, but which of course has output transformers presumably protecting the speakers? Thanks.
The speakers would not be in dc danger when transformer coupled. If a tube amp has no inter stage ac coupling though, it could kick its power stage to latch at B+ when strong DC will drive it and overload it, also overloading its transformer primary. That could take out expensive active and passive components depending on their power handling. By large majority they have a series capacitor at least on the grids of their output tubes, but better investigate the schematic of the intended power amp.
Thanks for your response Salas.
My power amp is a modern version of a classic tube amp design with SRPP input, a driver stage, then capacitor coupling to a push pull output stage.
Do you think it would be okay if DC got through or would the standard B1 be a better choice here?
My power amp is a modern version of a classic tube amp design with SRPP input, a driver stage, then capacitor coupling to a push pull output stage.
Do you think it would be okay if DC got through or would the standard B1 be a better choice here?
Very slim chance a DC breakdown feed could take out any serious components. The all important power stage and OPT are DC blocked.
My two DCB1 are all build and tested. They all have ~1mV DC offset which is really good.
Now I'm ordering the transfos from Antek and will get two 100VA but should I aim for 15Vac or 18Vac per secondaries? Please keep in mind that since the primary are 115Vac and that in my sector I have 120Vac the secondaries will be a bit higher than stated.
Thanks
Do
Now I'm ordering the transfos from Antek and will get two 100VA but should I aim for 15Vac or 18Vac per secondaries? Please keep in mind that since the primary are 115Vac and that in my sector I have 120Vac the secondaries will be a bit higher than stated.
Thanks
Do
100VA for the DCB1 x 2 seems a little excessive, considering at 200mA and +/-20V they only require 8VA.
I'm running mine at 150mA and using a 50VA toroidal.
I'm running mine at 150mA and using a 50VA toroidal.
From AndrewT (post #2260)
A DCB1 draws continuous current from the PSU.
That continuous DC current is ~=your CCS current, i.e. 600mA per polarity.
I recommend that the transformer be rated to >=~twice this AC current, i.e. 1.2Aac
15-0-15Vac 1.2Aac centre tapped transformer or 0-15, 0-15Vac 1.2Aac dual secondary transformer is suitable for a 600mA DCB1. 50VA should run a little cooler than a 36VA transformer. For cooler long term running, I would double the current rating again to 2.4Aac, i.e. ~72VA.
A DCB1 draws continuous current from the PSU.
That continuous DC current is ~=your CCS current, i.e. 600mA per polarity.
I recommend that the transformer be rated to >=~twice this AC current, i.e. 1.2Aac
15-0-15Vac 1.2Aac centre tapped transformer or 0-15, 0-15Vac 1.2Aac dual secondary transformer is suitable for a 600mA DCB1. 50VA should run a little cooler than a 36VA transformer. For cooler long term running, I would double the current rating again to 2.4Aac, i.e. ~72VA.
I couldn't hear any difference with running the SALAS Shunt Reg at currents above 300mA. In the end I opted for 160mA (ish), the MOS-FETs run cool and there is no danger of component cooking.
Irrelevant of the current the PSU is consuming, the B1's run at about 7-10mA each (determined by the Idss of the 2SK170BLs).
The 2E heatsinks run at a nice cool 30 degrees at 200mA but start to heat up rapidly above 300mA.
Irrelevant of the current the PSU is consuming, the B1's run at about 7-10mA each (determined by the Idss of the 2SK170BLs).
The 2E heatsinks run at a nice cool 30 degrees at 200mA but start to heat up rapidly above 300mA.
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Thanks to all.
I will be testing at different current. I've just ordered 2x 100VA from Antek since they only have 50VA and 100VA. The price was about the same. This will enable me to test various scenarios. I have some HeatsinkUSA 10.080 profile in stock so heat should be under control.
My goal is to have a good balance of sound and heat. I might end up doing 300mA in the end but will make my own tests.
Do
I will be testing at different current. I've just ordered 2x 100VA from Antek since they only have 50VA and 100VA. The price was about the same. This will enable me to test various scenarios. I have some HeatsinkUSA 10.080 profile in stock so heat should be under control.
My goal is to have a good balance of sound and heat. I might end up doing 300mA in the end but will make my own tests.
Do
You wont go wrong with either 50VA or 100VA. Usually it comes down to size or cost.