Re: Rode NT1-A requires 3 minutes warm-up time
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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Re: Rode NT1-A requires 3 minutes warm-up time
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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"Quick test showed high signal on lowest setting in DR-70D, knob on "twelve o'clock". Plenty gain left to use."
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Hmmm.... Got me thinking that the signal might be too hot for a train...
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Re: Rode NT1-A requires 3 minutes warm-up time
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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On Sat, Nov 2, 2024 at 10:14 PM, Johan Vandermaelen wrote:
Nice options, but much lower output than a standard piezo disc. Cancsooundok however.
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Can't complain. I just put together an circuit (in a BM800 body)? and connected one of?these:
Works like a charm. Quick test showed high signal on lowest setting in DR-70D, knob on "twelve o'clock". Plenty gain left to use.
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The piezo element unshielded, on a long (+/- 70 cm) cable. No noise whatsoever.
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Will try the flex one soon.
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Re: Rode NT1-A requires 3 minutes warm-up time
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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Re: Rode NT1-A requires 3 minutes warm-up time
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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Re: Rode NT1-A requires 3 minutes warm-up time
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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Nice options, but much lower output than a standard piezo disc. Cancsooundok however.
"I'll see your vest and raise you a hard hat."
And I'll wave you back, mate. ;)
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" I used to joke how if you put on a hard hat, hi-viz vest, steel toe boots, and carry a clipboard, you could probably get into Area 51."
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I'm in a mobile hydraulic hoses emergency service, up until March I used to go into construction sites (a.o.) as well. Since we do not have Area 51 here, in Poland, I use to say that HiViz jacket set makes you invisible."
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Funny you mention a raiway bridge. We have a steel one, here in Warsaw (wonderfully noisy), it's on my bucket list.
I only need to need to populate the PCB boards....
Akhem...
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So far I bought (from Ali) such, alernative to typical piezo elements, which may be of interest for you:?
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Or these:
Waterproof and easier to attach to surfaces than a typical piezo. Also doesn't require shielding.
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Also:
Self shielding as well.
Havent tried these yet how they work attached flat. Will try to buid a sort of a geophone - the piezo strip clamped at one end and wieghted at the other.
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Re: Rode NT1-A requires 3 minutes warm-up time
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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Re: Rode NT1-A requires 3 minutes warm-up time
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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"I'll see your vest and raise you a hard hat."
And I'll wave you back, mate. ;)
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" I used to joke how if you put on a hard hat, hi-viz vest, steel toe boots, and carry a clipboard, you could probably get into Area 51."
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I'm in a mobile hydraulic hoses emergency service, up until March I used to go into construction sites (a.o.) as well. Since we do not have Area 51 here, in Poland, I use to say that HiViz jacket set makes you invisible."
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Funny you mention a raiway bridge. We have a steel one, here in Warsaw (wonderfully noisy), it's on my bucket list.
I only need to need to populate the PCB boards....
Akhem...
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So far I bought (from Ali) such, alernative to typical piezo elements, which may be of interest for you:?
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Or these:
Waterproof and easier to attach to surfaces than a typical piezo. Also doesn't require shielding.
?
Also:
Self shielding as well.
Havent tried these yet how they work attached flat. Will try to buid a sort of a geophone - the piezo strip clamped at one end and wieghted at the other.
?
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Re: Rode NT1-A requires 3 minutes warm-up time
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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Ha! Funny you should mention the hi-viz vest. I'll see your vest and raise you a hard hat. I used to work at an engine plant and had to go into construction zones regularly as part of the new model program. I used to joke how if you put on a hard hat, hi-viz vest, steel toe boots, and carry a clipboard, you could probably get into Area 51. Just kidding, but your suggestion is a valid one.
I think contact mics are the way to go. Another thing that would be interesting is putting contact mics on a steel rail bridge when a train goes over. You could be under the bridge on the ground well away from the moving train and I suspect the sound would travel right through the steel supports down to the ground. Might sound really cool.
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Re: Cheap electrets that go up to 40kHz?
I personally tested many electret capsules and if you don't need to listen to very high frequencies then EM272 easily reach 60kHz with a good sensitivity
Iv
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Re: Cheap electrets that go up to 40kHz?
On Thu, Oct 31, 2024 at 08:50 PM, cx b wrote:
Can MEMs be powered in a similar way to the "Simple P48
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Not quite.? Analogue MEMs mics - like the one I referenced to - are unbalanced devices.
I use the circuit here to interface a MEMS capsule with a phantom powered balanced mic input, to record bat ultrasound.
?This circuit provides c.2.5v to the MEMS capsule...... Analogue MEMs mics do not like over voltage!
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Re: Rode NT1-A requires 3 minutes warm-up time
Hi Heinz,
Troubleshooting electronics is a topic of interest to any mic builder.
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How to interpret your meter test result using Ohm's law:
Battery measured directly = 6.47V
Measured with .542M in series = 4.17V
(from here, I¡¯m going to round everything off to make it easy to calculate in my head}
Meter dropped by around 1/3
so 1/3 of the voltage is dropping across 1/2M
2/3 is dropping across the meter, ergo the meter is twice the resistance of the 1/2M resistor
meter resistance is 1M
I know that from having used and measured a lot of meters in the past. Common multimeters are either 1M or more expensive 10M ones. Even really cheap $10 ones are very accurate if they haven¡¯t been abused.
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Now as to your meter vs your NT1A, a 1M meter is going to present a heavy load to the capsule bias generator, so it¡¯s not going to read that voltage accurately. The filter circuit contains a 4.7M resistor which will drop 5/6 of the voltage, leaving 1/6 across the meter, but that¡¯s not the worst of it. The bias generator is designed for no load current at all, and ANY current draw will cause it to deliver less than the designed voltage. So just take it that your meter can¡¯t measure the voltage across the capsule with any accuracy.
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You¡¯ve determined that the capsule bias doesn¡¯t change when the mic starts working, so let¡¯s assume the bias circuit isn¡¯t at fault.
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Unfortunately also, since the NT1A circuit is a DC-coupled non-inverting op-amp, if any voltage is out of spec anywhere, none of the voltages will be normal anywhere.
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My instinct says the capsule is the most probable cause because:
1) it¡¯s edge terminated, and edge terminated capsules tend to leak more than center terminated.
2) Matt (mic-parts & Roswell) tells me edge terminated capsules tend to give trouble at more than 80V. They don¡¯t collapse until 120V or more, but they may become leaky over time, and the NT1A circuit is very sensitive to leaks, since the capsule is directly connected to the gate of the FET. Matt has seen a LOT more capsules than I have. And R?de runs their capsule at 100V.
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So let¡¯s measure a voltage someplace like the junction of D5 and D6 or anywhere else along that circuit line, the output of the op-amp. It should rest at 7.34V. Call it OK between 7V and 8V. My guess is, it will be way higher when the mic isn¡¯t working.
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Now unsolder the wire from the circuit at the capsule, so if the capsule is leaking it won¡¯t upset the electronics.
Did the op-amp voltage return to 7 - 7.5V? If so, the capsule is at fault. If not, the fault is on the circuit board.
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An alternate troubleshooting method is to swap the capsule with a known working one from another mic. That has the disadvantage of possible damage to TWO mics, and you may not have another mic to risk. OTOH, it tests both the NT! capsule in a good mic, and puts a good capsule in the R?de.
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Le 31/10/2024 ¨¤ 19:16, Richards a ¨¦crit?: Hmmm... a guy named CASEY talking about trains ... yeah, that works !! :-)
What about a contact microphone like we used to use with telephone handsets? These are not microphones. They are just inductivecoils that pick the radiated magnetism.
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Re: Cheap electrets that go up to 40kHz?
Can MEMs be powered in a similar way to the "Simple P48"?
[Edited Message Follows]
The EM258 has a very useful ouptut at 40KHz.? ?At 80Khz it's almost nothing -- although it will still register something, just above the noise!
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MEMS microphone capsules like those listed here: ? ?have a much better ultrasonic response.
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On Mon, Oct 28, 2024 at 11:51 PM, Jonas Gruska wrote:
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Primo EM258 goes up to 80 kHz.
Hi all -
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Any recommendations for cheap-ish electret elements that go up to 40kHz?
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Thanks!
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Hmmm... a guy named CASEY talking about trains ... yeah, that works !! :-)
What about a contact microphone like we used to use with telephone handsets? Or a past-on guitar or instrument pickup (although I suppose those are piezo units which is where you started from ) but some sort of acoustic instrument pickup that can be pasted to the instrument/tracks?
I sort of like the piezo idea - as they are ready made and suitable for contact pickup - but then, piezo pickup are not exactly accurate sound capturing.
Interesting question. James
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Mark Day
Ivano Pelicella