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I would like to give a final update on this (marathon) thread.
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Even if the NT1-a isn't turned on for a while, it still works. No warm-up time is necessary...
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I recently used it to record from close range. Some of the instruments had low-frequency, resonant and complex sounds. The on-site forest ambiance was recorded using a pair of AOM-5042Ls () mounted on a . The lava stone sound samples were added in post.?
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So far I am satisfied with the recording results of the NT1-a.
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R?DE support has also provided a final update:
Glad to hear all is well with your NT1-A, greater sensitivity is the double-edged sword of condenser microphones!?
Condenser microphones in general are more delicate and sensitive when compared to dynamic microphones, if you could continue to store your NT1-A similarly (in a zip lock bag together with the silica pads) when not being used that'd be greatly appreciated!
Thanks for letting us know about your proof of purchase (a signed self-receipt...), unfortunately we would need an original proof of purchase from an authorised dealer to carry out a warranty claim. If the reuse store you bought the microphone from could provide this to you, we'd be able to process a warranty claim with you in future!
Next time I will ask for a proof of purchase. Just in case...
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Thank you all for your contributions!
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Heinz
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When I connected the NT1-a to the audio interface today and turned on phantom power, it worked right away. I feel like the microphone is gradually working and sounding better since we started narrowing down the problem. For the past few days, when I'm not using the NT1-a, I've been storing it in a zip lock bag together with the silica pads. In addition, the environmental conditions have changed. It is no longer hot and humid and temperatures have dropped to between 8°C and 17.1°C (46,4°F and 62,6°F). Since the NT1-a seems to be very sensitive to humidity, this could also have a positive effect. All in all, I am very happy with this result and would like to thank you for your contributions and tips! I have learned a lot about dealing with used and non-functioning microphones and hope that this thread was also interesting for other mic builders. I like the fact that the NT1-a has very low self-noise and will experiment with it in the field. MANY THANKS!
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On Wed, Nov 6, 2024 at 08:21 PM, Jerry Lee Marcel wrote:
This seems correct.
What about when the mic doesn't work?
Hi Jerry. Here are the results from today but I'm not sure if I was fast enough to measure all points before the mic started working. At some points I had to wait until the value on the scale settled. I'll try again tomorrow.
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A=6.58
B=8.42
C=1.30
D=0.63
E=8.24
F=16.32
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Do you know about a possibility maybe, to force the non-functional state? For example discharging all caps with a resistor (or one-by-one, to find the faulty slow charging one?) instead of waiting one day until the warm-up error occurs again? I'm just wondering.
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Yes, that should work well - especially with the large number of gel packs toss in the bag after the washing machine. Yes, fine business. :-)
The capsule should be fine - they work well - BUT you may need to pay attention to the bias voltage level ... ask the experts whether the cheaper Chinese capsules can run at the higher voltage produced by RODE boards. Otherwise OK.
And, I have used various edge terminated capsules from Chinese vendors on eBay.com with satisfying results -but I realize your mileage may vary - check the voltage levels in any case.
Just my take. James
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Many thanks Jerry!
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It was a bit hard to read, that's why I wanna make sure I measured the right points.
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I will measure the non-functioning state tomorrow at about the same time and send you the results.
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This seems correct.
What about when the mic doen't work?
Le 06/11/2024 à 11:29, Heinz a écrit?:
toggle quoted message
Show quoted text
On Wed, Nov 6, 2024 at 06:31 PM, Jerry Lee Marcel wrote:
Can you read the voltages on the various points?
Here you will find the results (mic working state):
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A=5.04
B=7.64
C=1.16
D=0.55
E=7.50
F=15.36
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On Wed, Nov 6, 2024 at 06:31 PM, Jerry Lee Marcel wrote:
Can you read the voltages on the various points?
Here you will find the results (mic working state):
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A=5.04
B=7.64
C=1.16
D=0.55
E=7.50
F=15.36
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On Thu, Oct 31, 2024 at 07:45 PM, Jerry Lee Marcel wrote:
Can you check the various voltages circled in red in both cases?
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Hi Jerry. I measured various voltages on the circuit board in the working state (with reference to ground) but I'm sure I missed some. Can you circle the points on the circuit board that I missed?
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I apologize for the triple post. For some reason the pictures got messed up...
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Having a spare capsule around is handy. A K47 copy isn’t acoustically like the original capsule, but it will work with the R?de flat-response circuit and is a popular upgrade. Edge terminated capsules have a large area around the outside of the capsule where moisture or fingerprints can cause leakage between the diaphragm clamping ring and the backplate. This is usually wrapped with insulating tape, but it is still more likely to leak than the insulating ring (the part of the diaphragm not covered by gold) around the edge of a center terminated capsule.
If you become interested in building mics, you will naturally accumulate capsules and circuit boards as you upgrade and experiment.
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I have no experience with the NT1A and the proposed capsule. So I cannot be of any help here. I would guess that screw hole locations and maybe capsule thickness are items to check before purchasing any capsule.
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Jan
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On Tue, Nov 5, 2024 at 03:35 AM, Richards wrote:
You might consider accumulating multiple packs and sealing them with the capsule in a plastic bag.
Hi Jan & James
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Many thanks for your suggestions!
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I threw it into the washing machine again and am now letting it dry. The coin laundry's nearby also have very effective shoe dryers.? Should I try one out?! :-) I'm not really convinced it will help either.
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Joking aside...
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From what I heard and learned so far, the edge terminated capsules don't have the best reputation. I would really like to follow Henry's alternate troubleshooting ( #39676) method suggestion and swap the capsule.? It seems that are currently available for the equivalent of $20. But it doesn't look particularly trustworthy. Do you think these might work when connected to the NT1-a circuit? Or should I rather refrain from doing such exercises?
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On Sun, Nov 3, 2024 at 02:44 AM, Heinz wrote: answer from Rode. They suspect that the issue is moisture and humidity related and would like me to store the microphone with a silica packet in a cool, dry place for 24 hours, __________________________________________________________ Serving Suggestion: I have used silica packs to dry stuff out - especially camera gear. You might consider accumulating multiple packs and sealing them with the capsule in a plastic bag. My wife manages a major clothing department store and brought home dozens of silica gel packs from various departments - gifts, shoes, handbags, and so forth. You might be able to collect several fresh packs of silica gel from a local store and give it a really good drying out! I have done this for camera lenses, microphones, and other gear with good results. I do not believe you can have too much, but then I am not a chemist, so you are on your own, but I believe one is good, several are "gooder." You be the judge. :-) Lotsa luck, old man. James
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From an earlier post, where you measured the voltages around the capsule during working and non working periods, there seemed nothing wrong. That would have been the area where I'd expect moisture to wreak havoc your circuit. The CMOS oscillator is also somewhat sensitive, but it seemed to work alright, given the capsule polarization voltage was present. So I'm not convinced that the R?de solution would work, but it's worth trying of course.
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You may have guessed it yourself already, but if you want to use an ultrasonic cleaner, then only clean the PCBA. Do not inmerse the capsule! Use a suitable? cleaning fluid. DIY recipies for cleaning fluids can be found on the web. Use demineralized water and thoroughly dry the the PCBA in an oven at 75C for several hours. If C8 does not have small standoffs, reflow one of its solder pads and lift one end a bit, so the fluids can reach that area. And at least as important, can also evaporate.
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Good luck!
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Jan
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On Sun, Nov 3, 2024 at 03:52 AM, Richard Lee wrote:
The fact that cleaning the PCB solved the problem, at least temporarily, suggests it is muck on the PCB.? If there are no EVIL polystyrenes, it might be worth doing this again; perhaps in an ultrasonic bath.
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I somehow have a bad feeling about the capsule connection. The red one in particular seems old, brittle and slightly bent. I checked the cable for breaks with the DMM, but unfortunately could not find any fault.
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I would also like to take a look behind the cover on the backside of the capsule.
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I will do another long-term recording test tonight. Tomorrow I'm visiting someone who may have an ultrasonic bath.
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Many thanks!
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On Sun, Nov 3, 2024 at 12:02 AM, Henry Spragens wrote:
What a lovely old meter! Japanese? As used by technicians during WW2? It's essentially a 1mA meter with series resistors selected by the voltage range switch, so that at the full scale voltage, 1mA of current flows thru the meter. As a result, it doesn't have a fixed input resistance like a modern digital meter. It has a sensitivity of 1000 ohms per volt.
Hi Henry
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That's what I was interested in. Whether the meter behaves like a digital one in terms of input resistance or not. Many thanks!
I opened it carefully and took another two screenshots from inside. It looks more like the inside of an old clock or a kind of Antikythera mechanism from ancient Greek. :-) There is a small compartment at the top which means "Shunt" 1MA200MV (1Milliampere,200Millivolt)? I didn't open it yet. The meter is Japanese.?
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Regarding the NT1-a I got an answer from Rode. They suspect that the issue is moisture and humidity related and would like me to store the microphone with a silica packet in a cool, dry place for 24 hours, to dry up the capsule and resolve the issue. To investigate further, they asked me to provide an audio or video sample demonstrating the issue. I will provide the information they requested until next Wednesday.?
Additionally, the following note was added:
It's also important to note that seeing as you've purchased your microphone second hand, it unfortunately not covered under warranty, this means that any potential repairs will be up to the discretion of your local distributor.? For now, I would recommend running through the above steps to see if they resolve the issue and then once we hear back from you we can proceed down that route if required.
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Let's see what Rode suggests. I'll keep you up-to-date. Should I point them to this thread? Or better not?
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Anyway. I find it more interesting to modify it myself than sending it in. Or if the capsule turns out to be the culprit, buy a capsule from Matt or Jules. We'll see.
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Heinz
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If the rest of y'all are getting bored, we can take this thread private.
Please keep this on the forum, Henry & Heinz.? This whodunnit story is becoming curiouser & and curiouser.
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My $0.02 is simply that if it is the capsule, it will be VERY noisy long before it stops working.? Of course you could be right that capsule leakage is mucking up the biasing of the amp.
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The fact that cleaning the PCB solved the problem, at least temporarily, suggests it is muck on the PCB.? If there are no EVIL polystyrenes, it might be worth doing this again; perhaps in an ultrasonic bath.
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What a lovely old meter! Japanese? As used by technicians during WW2? It's essentially a 1mA meter with series resistors selected by the voltage range switch, so that at the full scale voltage, 1mA of current flows thru the meter. As a result, it doesn't have a fixed input resistance like a modern digital meter. It has a sensitivity of 1000 ohms per volt. That is, the resistance on the 10V scale is 10K. On the 100V scale, 100K, etc. There were more expensive meters with 100uA movements, but they were too delicate for field work. Anyhow, there is usually a fuse inside the box, and that is usually why old VOMs don't work. Finding a fuse to fit a gadget from Japan 3/4 of a century ago may be impossible.
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As for the mic, tracing SMT circuits is not easy. I haven't seen an NT1A myself, so I'm looking at your photos and the circuit as found on the WWW. What to do when the culprit is found may be interesting. If the capsule is leaky, try cleaning around the edges? Add an input capacitor and another 1G resistor between the capsule and the FET? That way, a small leak at the capsule won't upset the circuit, but the mic won't be "as designed" any more, and the capsule may turn out to be noisy. If the culprit turns out to be a component on the PCB, obtaining a two-penny part and replacing it will be a nuisance, but the process is instructive.
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If the rest of y'all are getting bored, we can take this thread private.
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On Fri, Nov 1, 2024 at 08:50 AM, Henry Spragens wrote:
Troubleshooting electronics is a topic of interest to any mic builder.
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Hi Henry. Thank you for your detailed answer!
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You pointed it out very clear that my meter can’t measure the voltage across the capsule with any accuracy and why. Many thanks! The meter is like an attached parallel circuit right?
Which reminds me of an analogue measuring device I bought on a flea market two years ago. Unfortunately, the voltage measurement no longer works, but the resistance measurement is still OK. It's an IWASAK Universal Tester. According to the labels on the scale, it's from 1947.?
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I always loved troubleshooting and finding the needle in the haystack in network environments, file servers, various operating systems, routers and switches when I worked as a SE and 3rd level supporter. After more than 25 years of experience, the intuition you develop can often be a great help. But usually the error analysis ended when the defect piece of hard- or software was found. The defective part was replaced. Array controllers, system mainboards, network interface cards, power supplies, defect hard discs, memory, fans. To name a few. There was no need to investigate further and to find the culprit in the circuit.
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When it comes to micbuilding and circuit error analysis I'm an absolute noob. That's why I appreciate your help. It's like learning a new language which can be overwhelming in the beginning (A, AT, BR, C, D,...ZN). I even struggle to find the parts or correct measurement points that you or Abbey mentioned in the schematic.
The SMD components are so tiny. So usually I end up with an eyepiece in one eye, a light in my right hand (or on the desk) and the circuit of the NT1-a in my left hand. Watching closely :-) Or zooming in to the circuit photos I send to you. Identifying the part description of these tiny little pieces and searching for it on the internet and for the schematic equivalence. The difference between what's drawn in the schematic and the real thing. Matching nodes, branches and circuit lines?! It's like a huge puzzle. What makes things even more puzzling is that the lines in a schematic diagram do not necessarily represent the specific point-to-point order of the connections the corresponding real circuit might have.
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I obviously don't want to bother you guys with each and every question that comes to mind. It's a learning process and if I want to build (bamboo) microphones, I should go through the books and at least understand the very basics. But I must admit that I was tempted to ask you and Abbey to number the measurement points on the schematic and the corresponding points on the circuit. What I don't do is measure points without knowing whether it's the right one or not. That's why it needs some time to answer your questions. So don’t worry if you don’t hear from me for months. :-)
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I'm sorry Henry, but I don't have a proven large diaphragm capsule from another working microphone yet. Although I would like to follow your intuition.?
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Many thanks!
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Heinz
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