Length of the secondaries
I will be using the SSLV's to power my dual mono OPUS / Amanero DAC. I don't want to end up with a very large chassis, so I'm planning to place the transformers in another chassis, but then a question came to mind. Is to OK to have 30cm to maybe even 40cm long secondaries from the transformers?
The photograph shows how I planned the layout inside the DAC chassis. I currently have some 10R resistors for R101, R201 and R301. Maybe this will be generating to much heat inside the small chassis. The chassis is just 25x20x7cm. I might need to raise the values for R101, R201 and R301 as there is no room for large heatsinks.
I will be using the SSLV's to power my dual mono OPUS / Amanero DAC. I don't want to end up with a very large chassis, so I'm planning to place the transformers in another chassis, but then a question came to mind. Is to OK to have 30cm to maybe even 40cm long secondaries from the transformers?
The photograph shows how I planned the layout inside the DAC chassis. I currently have some 10R resistors for R101, R201 and R301. Maybe this will be generating to much heat inside the small chassis. The chassis is just 25x20x7cm. I might need to raise the values for R101, R201 and R301 as there is no room for large heatsinks.
Attachments
Long AC cabling is not harmful to the power delivery since the transformers will already have substantial output impedance anyway, but it can spread significant AC field around which may interfere with nearby signal cabling and components.
It would be neater to unsolder the diodes, move them to the transformers box, make two bridges there, add another two of same smoothing reservoir capacitors.
So to rectify and filter locally and then transfer "raw" DC to the regs directly to their local reservoir pins.
It would be neater to unsolder the diodes, move them to the transformers box, make two bridges there, add another two of same smoothing reservoir capacitors.
So to rectify and filter locally and then transfer "raw" DC to the regs directly to their local reservoir pins.
I did this is my preamp. I was worried about grounding and of course hum. I connected the grounds of the two rectified (with smoothing capacitors) voltages together in the transformer chassis and brought one ground into the preamp and had every ground in the audio chassis connected at a single point. It worked, no hum.
Rush
The obvious solution is to build Mr. Linkwitz's subwoofers and xover, and maybe add a little subsonic filtering there. I'll start negotiations with the wife.
Capacitance of the smoothing caps
Also should there be a single ground point inside the DAC chassis or in the chassis that will contain the transformers and rectifiers? Maybe both?? Just trying to figure out what's the best practice.
That's sounds like a good idea and easy to implement. Is 2 x 2200uF enough for the smoothing caps or did you mean the same as I used on the SSLV regulator boards?
Also should there be a single ground point inside the DAC chassis or in the chassis that will contain the transformers and rectifiers? Maybe both?? Just trying to figure out what's the best practice.
Each system may present its own grounding quirks but what Rush said is a safe initial scheme.
The current draw will be about 100 -150mA without shunt. 100mA for the DAC board and 90-150 mA for the IV stage. The DAC's analog and digital sections will have it's own supply just like the IV stage.
Like I said before R101, R201 and R301 probably need to be increased to keep the chassis at a reasonable temperature. I'm planning to increase them to 20R. That would mean a total current draw of 200mA for each supply and probably not generating too much heat at the capacitors in the transformer chassis at this level. I have a bunch of Philips 2200uF radial caps waiting to be used. I'll be happy if these can be used without (heat) problems, so I don't need to buy new ones.
Like I said before R101, R201 and R301 probably need to be increased to keep the chassis at a reasonable temperature. I'm planning to increase them to 20R. That would mean a total current draw of 200mA for each supply and probably not generating too much heat at the capacitors in the transformer chassis at this level. I have a bunch of Philips 2200uF radial caps waiting to be used. I'll be happy if these can be used without (heat) problems, so I don't need to buy new ones.
Voltage won't reach 15V
I fired up the my positive SSLV. All worked fine, but it could not reach 15Vdc somehow.
I started with this setup:
15Vac (80VA) transformer (actually measures 16.2Vac)
R103 = 1K
R105 = 2K trim pot
dummy load resistor: 50R (5W)
Maximum voltage that could be set: 14.1V
Then I increased R103 to 2.2K and kept all other components the same, but the voltage could still not exceed 14.1V
increased R103 again to 4.7K, but still the voltage can't be set any higher than 14.1V.
I don't understand why, but there is obviously something preventing me from adjusting it to 15 Vdc. I Attached a photograph to show how I connected the dummy load resistor. I connected it per the manual. The other picture shows the regulator part (2 LED's, zener jumpered, R103=resistor and R105=2K trim pot), I know it's not a very clear photograph...
I fired up the my positive SSLV. All worked fine, but it could not reach 15Vdc somehow.
I started with this setup:
15Vac (80VA) transformer (actually measures 16.2Vac)
R103 = 1K
R105 = 2K trim pot
dummy load resistor: 50R (5W)
Maximum voltage that could be set: 14.1V
Then I increased R103 to 2.2K and kept all other components the same, but the voltage could still not exceed 14.1V
increased R103 again to 4.7K, but still the voltage can't be set any higher than 14.1V.
I don't understand why, but there is obviously something preventing me from adjusting it to 15 Vdc. I Attached a photograph to show how I connected the dummy load resistor. I connected it per the manual. The other picture shows the regulator part (2 LED's, zener jumpered, R103=resistor and R105=2K trim pot), I know it's not a very clear photograph...
Attachments
My bad. I used the wrong voltage to calculate the dummy load resistor.
I used 7,5V in the calculation instead of 15V.
Expected current draw: 90-150 mA
15 / 0.15 = 100R instead of 7.5 / 0.15 = 50R
Lightening it 3 fold is not an option as the IV can draw currents up to 150mA. Perhaps it's better to lower the CSS. I was already planning on doing that, but I just wanted to know if the supplies where working. Tomorrow I'll raise the dummy load to 100R and see what happens.
I was under the impression that the SSLV could supply much larger currents, but maybe I'm confusing the with the HOT ROD DBC1 supply. What is the advised CSS for powering a 90-150mA device?
I used 7,5V in the calculation instead of 15V.
Expected current draw: 90-150 mA
15 / 0.15 = 100R instead of 7.5 / 0.15 = 50R
Lightening it 3 fold is not an option as the IV can draw currents up to 150mA. Perhaps it's better to lower the CSS. I was already planning on doing that, but I just wanted to know if the supplies where working. Tomorrow I'll raise the dummy load to 100R and see what happens.
I was under the impression that the SSLV could supply much larger currents, but maybe I'm confusing the with the HOT ROD DBC1 supply. What is the advised CSS for powering a 90-150mA device?
Lighten the test load to 150R I meant. So to represent 100mA for 15V. Lowering the CCS just for dummy test purposes is a drag.
Or use 2x50R in series if you haven't got other handy. Anything in the ballpark of your real conditions to be. So to test and set, also evaluate the heat.
With a 9610 CCS up to 1000mA is safe. But you set the limit. For 150mA load, 250-300mA CCS is a nice point.
Divide the voltage drop across R101 by its value. That is your now real CCS setting. Know that first and then decide the dummy load.
Or use 2x50R in series if you haven't got other handy. Anything in the ballpark of your real conditions to be. So to test and set, also evaluate the heat.
With a 9610 CCS up to 1000mA is safe. But you set the limit. For 150mA load, 250-300mA CCS is a nice point.
Divide the voltage drop across R101 by its value. That is your now real CCS setting. Know that first and then decide the dummy load.
Seems OK. That'll give you 15V rms across the outside windings with the center tap at ground. Use a 2 diode configuration. Voltage might be a bit high, but you can also use a dropping resistor to bleed a bit of that voltage down if needed.