Another possibility: if their software samples the waveform at (let's just say) 1000 points to calculate RMS, but they only use two of those points (the biggest and the smallest) to calculate Pk-Pk, then the RMS calculation is much much more tolerant of ADC errors {and slight waveform distortion} than the Pk-Pk calculation. Eureka, ick and crud and noise gets smoothed out through averaging. Maybe that's why they only display Pk-Pk to 3 significant figures instead of the 5 siggy figgies on the RMS calculation.
A phone call to Keysight might clarify this issue. I’ve called them before, very helpful fellas. Love the scope though, especially the FRA (Bode) plot feature which is a nice quick check to see that no major mishaps are occurring.
Best,
Anand.
Best,
Anand.
In both scope displays the pk-pk after dividing by 2 for pk value both divisors are different (1.4398... and 1.4507...) and not the standard sqrt 2 (=1.4142...) to get the RMS value.
Another pair of F5m Redux getting ready to fire up! Hope to get time over the next few days to perform initial power up (already confirmed P/S rails are OK) and bias them up.
These will replace the ACA Redux in my bedroom system.
Dan
These will replace the ACA Redux in my bedroom system.
Dan
A question for @N Brock, what is your source for the little metal thumb-screws? I would like to use a set on the bottom nylon standoffs. "Feet" as it were.
And, a helpful hint: the rubber tubes will fight you trying to slide them over the upper standoffs. Needs lube. Silicone would work nicely, but my knees (one of the reasons that I was sitting at my workbench) were killing me and I really did not want to walk all of the way to the garage. Looking around my workbench, used a little squirt of F5 Fader Lube. The rubber tubing slides nicely into place!
Dan
And, a helpful hint: the rubber tubes will fight you trying to slide them over the upper standoffs. Needs lube. Silicone would work nicely, but my knees (one of the reasons that I was sitting at my workbench) were killing me and I really did not want to walk all of the way to the garage. Looking around my workbench, used a little squirt of F5 Fader Lube. The rubber tubing slides nicely into place!
Dan
You could investigate Keystone Electronics @DCE1198 , Mouser.com is one of their distributors
Thumb Screws
Thumb Screws
And... amp(s) update. The F5m Redux are all biased up and the offset trimmed. Settled in nicely at about the 30 minute mark. Now it is off to the listening room!
Dan
Dan
I'm working on the amps and I'm at the step in the guide where I check for shorts between the pads of L2 to ground and L4 to ground. It says the resistance should be over 500k ohms at both. I'm getting a reading at L4 on both amps but nothing at L2 on either amp. How do I work through the circuit to see whats wrong and what am I testing for? I have built the ACA Redux before this but that is my only kit experience till now. Thanks in advance.
I'll make a note to clarify in the guide.Okay, amps are completed. One the fan runs intermittently and the LED flashes. The other amp seems okay.
I can't upload a video. Where should I start looking for problems?
I can't upload a video. Where should I start looking for problems?
Also, I'm not clear on the biasing paragraph. "Both should read 0V at this point" when one multimeter is connected to output terminals and the other across R6 or R7. They did at first. I don't understand what I'm supposed to be doing next. I'm turning the potentiometers but not getting any change at the reading at the output terminals, or across R6/R7. The readings are fluctuating at the resistors, but steady at 0.3 V across the outputs. Turning pot screws does not appear to have any effect.
Sorry if I'm not understanding something that's simple to you guys but like I said, its my second kit.
Sorry if I'm not understanding something that's simple to you guys but like I said, its my second kit.
I'm no expert, but blinking LED points to the SMPS power supply in hiccup mode, which means you likely have a short somewhere and the PSU is protecting itself. I would check the AmyAlice filter components (smd feedthru caps are a good place to start) to see if you can find a short to ground. You can probe with DMM in resistance mode (power off and unplugged of course) for shorts.
I'm sure more knowledgeable folks will chime in as I'm pretty new to all this. I just happen to have the same issue as you with the blinking LED and it happened to be shorted feedthru caps (yes, more than one was shorted to ground).
I'm sure more knowledgeable folks will chime in as I'm pretty new to all this. I just happen to have the same issue as you with the blinking LED and it happened to be shorted feedthru caps (yes, more than one was shorted to ground).
On the amplifier that is acting up, flip it over and take a good, high resolution photo of the entire board and upload it. That way, we can all enlarge the image and go sleuthing.
When adjusting the pots, your DMMs need to be on the millivolt range. You need the resolution to perform the adjustments properly. If you have preset the pots as stated in the instructions, it takes a lot of turns before they begin having an effect. Take your time, keep the pot adjustments fairly even. As you get close to the specified bias current, tiny adjustments will make big changes. Everything will drift as the amplifier warms up. Mine did not reach equilibrium until the 30 minute mark. Even moving your hand near the board to make adjustments will cause a slight change due to air currents. It will be a bit frustrating at times as some adjustments will make everything go "out of whack" but it will, eventually, all stabilize and dial right in!
Dan
When adjusting the pots, your DMMs need to be on the millivolt range. You need the resolution to perform the adjustments properly. If you have preset the pots as stated in the instructions, it takes a lot of turns before they begin having an effect. Take your time, keep the pot adjustments fairly even. As you get close to the specified bias current, tiny adjustments will make big changes. Everything will drift as the amplifier warms up. Mine did not reach equilibrium until the 30 minute mark. Even moving your hand near the board to make adjustments will cause a slight change due to air currents. It will be a bit frustrating at times as some adjustments will make everything go "out of whack" but it will, eventually, all stabilize and dial right in!
Dan
Birdbox and DCE1198 are giving good advice.
The power supply hiccup mode could also be one of the TVS diodes (D1, D2) the wrong way around, or one of the pots not turned down during assembly before bias.
The pots won't have any change until you get several (maybe up to 10) turns into the procedure. Alternating between them means one full turn on P1, then one full turn on P2, then back to P1 until the meters start to show a reading other than zero, then go by what the meters say.
I've got a fair bit of editing left to finish the build video which shows the biasing steps. Maybe I can copy / edit just that section to get it to you sooner.
Chalk up another completed pair. Both working great. If anyone is on the fence, this is a straightforward build with modest introduction to SMD (mostly as the result of the inclusion of an AmyAlice Mark Johnson filter). All parts included, instructions accurate, concise and well written - in short everything as anticipated given our previous positive experience with the ACA hedgehog Redux kit.
Daughter #2 came back from Grad school and we built these up over a couple of days with intermissions for Mince pies & Brandy butter and occasional nibbles of Cambozola and glasses of LBV. No surprises or issues aside from a minor unplanned reacquaintance with the adhesive properties of heatsink compound which appears attracted to absolutely anything and everything...
🙂
Having a great Christmas comparing with M2,
Many thanks Nelson, Nelson & Mark!
As an aside I think Nelson B. you mentioned something about evaluating a lead combiner for the four SMPS units... Any conclusions?
Daughter #2 came back from Grad school and we built these up over a couple of days with intermissions for Mince pies & Brandy butter and occasional nibbles of Cambozola and glasses of LBV. No surprises or issues aside from a minor unplanned reacquaintance with the adhesive properties of heatsink compound which appears attracted to absolutely anything and everything...
🙂
Having a great Christmas comparing with M2,
Many thanks Nelson, Nelson & Mark!
As an aside I think Nelson B. you mentioned something about evaluating a lead combiner for the four SMPS units... Any conclusions?