Just put your dmm in series with power supply. Dmm should be set to amperes Dc or miliamperes, depends on your dmm.
Other way is to put a resistor in series with dc source and measure the voltage across that resistor and using ohm law you can find current draw. Preferable minimum 1w resistor.
Ohm law: I = u/r
Other way is to put a resistor in series with dc source and measure the voltage across that resistor and using ohm law you can find current draw. Preferable minimum 1w resistor.
Ohm law: I = u/r
It depends on the XO that is used. If you have a Fox XO 80 mA is acceptable I guess. My examples measured over 70 mA with Fox XO's if I remember correctly. With other XO's it hovered around 50 mA.
Atupi, it is I = U/R (in capitals please). I is in Ampère, U is in Volt and R is in Ohm. Since much, but not all, field work in electricity was done by german scientists at that time many parameters are abbreviated from german words and/or names. This is no personal preference but a fact, can't change that. We should ignore the non standard notations like I = V/R and adhere to standard notations.
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That would be a very green Fox XO... I think the accuracy of the DMM used and/or the measured resistance of the bead together cause some inaccuracy....
Maybe it is wise to leave it unpowered and connect it. Switch it on and then briefly check if you have normal sound. If so it is a V3 that consumes little more than normal.
Of course but it costs no extra time or money to use the right terms and notations. I feel we do have a kind of class sometimes 😉 When learnt right from the beginning later on chances for confusion will be less. The point of using standards I guess...
Maybe it is wise to leave it unpowered and connect it. Switch it on and then briefly check if you have normal sound. If so it is a V3 that consumes little more than normal.
Of course but it costs no extra time or money to use the right terms and notations. I feel we do have a kind of class sometimes 😉 When learnt right from the beginning later on chances for confusion will be less. The point of using standards I guess...
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Agreed, accuracy of DMM and bead resistance only give an indication. Total current draw is now stabilised at 74mA quiescent, I presume that is acceptable?
Thanks
Ian
I had to do some RTFM work with my meter (Ryobi Tek-4) - but I'm right at 80mV. Bout time I lernt some stuff 🙂
BTW - the BA-3 and MyRef both hum with a self-contained Lexicon Omega unit - both BNC and RCA S/PDIF connection. So some sort of isolation appears to be needed with those two amps.
BTW - the BA-3 and MyRef both hum with a self-contained Lexicon Omega unit - both BNC and RCA S/PDIF connection. So some sort of isolation appears to be needed with those two amps.
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It's a long and steep road Bob...
Don't isolate, just correct the grounding of the amplifiers...
Yes it is. Now tell us how it sounds.
Don't isolate, just correct the grounding of the amplifiers...
Yes it is. Now tell us how it sounds.
I actually sent off a PM to one of the Pass gurus with a description of the problem and a copy of the BrianGT schematics earlier today. I don't have the background to start changing circuits on my own. I'll post as I learn.
No change of circuits needed I think (without knowing anything about these amps). I just think your grounding scheme has some eh... peculiarities. I earlier asked you about the PE wall sockets but it seems you skipped that one.
Some things are very simply looked over...
Some things are very simply looked over...
Just barely succeeded with the build - so I'll wait for a little assistance.
BA-3 LC
BA-3 breakout
The MyRef grounding is currently under discussion.
BA-3 LC
BA-3 breakout
The MyRef grounding is currently under discussion.
Bob, I can tell I would not just start with such amp projects. You have already climbed up a steep hill !
What is the thingie with the blue LEDs and potentiometers ?
What is the thingie with the blue LEDs and potentiometers ?
Sunbean 4 port controller. Low RPM = Red, High = Blue.(fully variable) Only need two ports, one for combined fans and one for the pump. I'm working on a small internal module that replaces that entire unit. Also an AC auto shut off for runaway temps.(LC F5 build in photo)
I'm hoping other Pass amp builders will be using the V3 and will be interested in their results.
BTW. the BA-3/PS schematics are published if anyone wants to take a shot at the grounding scheme.
I'm hoping other Pass amp builders will be using the V3 and will be interested in their results.
BTW. the BA-3/PS schematics are published if anyone wants to take a shot at the grounding scheme.
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One point of criticism: the white connector blocks you use have one thing in common. They are unreliable. Better use Phoenix or similar connectors.
Thanks, it seems I always run out of those and it's one of the few DIY items the local Radio Shack still has in stock. I'll get something better for final assembly.
Hi. I do not follow the connection with the DAC. I doubt it is the amp design (or fact they are Pass designs) in combination with the DAC is causing the hum. I see the picture - not sure I understand. You have a water cooled F-5? You also have a BA-3 - is it not completed and you are looking for advice on how to ground? Seems complicated, too many variables to sort.
O.K. The F5, BA-3 and MyRef power amps are all completed - other than the chassis externals and final show wiring. They all play wonderfully and have for months with either a battery powered - or optical source feeding the Mini2496 DAC.
A hum that seems to be a ground loop appears on all three when a copper SPDIF connection is established. The Subbu DAC V3 works just fine when attached to a Mackie unit and/or BrianGT monoblocks - totally hum free. So it appears there is something "different" in the BrianGT (and the Mackie Preamp) grounding paths that breaks or displaces that suspected ground loop.
With the Mackie Pre I'm using ballanced 1/4" TRS to RCA adapters for signal to the V3 - no hum. The BGT combo is RCA on both ends.
I have tried both BNC and RCA cables between the computer and the V3 - no difference.
The Pass amps employ a common ground between the power supply and the speaker feed. Ground is ground is ground.🙄 The Fremen Edition MyRefs have a floating ground that can be configured according to user option and chassis configuration. In either case they don't like to play well with the solid SPDIF ground. I even put the Mackie Pre between the V3 and the BA-3 and still got the hum.
As I write this I'm trying to mod the TORX optical converter module from the Mini2496 DAC to feed the V3. It won't answer the grounding issue but it will allow the V3 to be connected to the three power amps.
A hum that seems to be a ground loop appears on all three when a copper SPDIF connection is established. The Subbu DAC V3 works just fine when attached to a Mackie unit and/or BrianGT monoblocks - totally hum free. So it appears there is something "different" in the BrianGT (and the Mackie Preamp) grounding paths that breaks or displaces that suspected ground loop.
With the Mackie Pre I'm using ballanced 1/4" TRS to RCA adapters for signal to the V3 - no hum. The BGT combo is RCA on both ends.
I have tried both BNC and RCA cables between the computer and the V3 - no difference.
The Pass amps employ a common ground between the power supply and the speaker feed. Ground is ground is ground.🙄 The Fremen Edition MyRefs have a floating ground that can be configured according to user option and chassis configuration. In either case they don't like to play well with the solid SPDIF ground. I even put the Mackie Pre between the V3 and the BA-3 and still got the hum.
As I write this I'm trying to mod the TORX optical converter module from the Mini2496 DAC to feed the V3. It won't answer the grounding issue but it will allow the V3 to be connected to the three power amps.
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