mic pre for recording over 20khz
- Thread starter kambo
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Help Support GroupDIY Audio Forum:
I suspect many of the typical solid state "cohen" topology preamps could already do 100 kHz by opening up existing LPF roll offs.kambo said:
The THAT corp 1510 IC specs a small signal -3dB of 3 MHz at 60 dB gain... less gain will deliver an even higher half power point.
100 kHz should not be heavy lifting for a decent solid state preamp, but be careful to remove intentional LPF poles from the design.
JR
The microphone is more a limit than the preamp. Easy to find transistors good for MHz. But microphones must compromise sensitivity against bandwidth. A "speech/music" microphone usually falls off bad above 20KHz. Measurement mikes come in several ranges, lower sensitivity in exchange for flat response to 100KHz and beyond.
moamps
Well-known member
kambo said:
BK 4135 + modified (without input transformer) Great River MP2 8)
+1 check the mic data sheets...
an old DIY test for HF response is to jangle a key chain in front of a mic, the keys can make a bunch of output at 40-50kHz. Still short of 100k...
you probably want a small (low mass) instrumentation/ measurement condenser mic... If they do 100 kHz response they will probably promote that prominently in their literature. Most typical mics DO NOT do pass 100kHz flat.
JR
an old DIY test for HF response is to jangle a key chain in front of a mic, the keys can make a bunch of output at 40-50kHz. Still short of 100k...
you probably want a small (low mass) instrumentation/ measurement condenser mic... If they do 100 kHz response they will probably promote that prominently in their literature. Most typical mics DO NOT do pass 100kHz flat.
JR
Have a look at Dodotronic. They sell mics, preamps and ADCs for biology:
https://www.dodotronic.com/?v=2a47ad90f2ae
Not terribly expensive. Most others I came across are at least ten times the price, while adding little in features.
https://www.dodotronic.com/?v=2a47ad90f2ae
Not terribly expensive. Most others I came across are at least ten times the price, while adding little in features.
moamps
Well-known member
I used it for ultrasound measurement and for check some friend's Tannoy super tweeterskambo said:
. Right now I'm working on a design of stereo recording setup for live concerts recording with these microphones, among others.Datasheet is here
https://www.bksv.com/media/doc/Bp0100.pdf
This guy uses it for live concerts recording.
http://www.metaxas.com/recordings.html
moamps said:I used it for ultrasound measurement and for check some friend's Tannoy super tweeters
Datasheet is here
https://www.bksv.com/media/doc/Bp0100.pdf
This guy uses it for live concerts recording.
http://www.metaxas.com/recordings.html
thanks,
i cant find info re mics its pinout/connections requirements : 100v - 20v etc connections, how much m amp etc pulling...
there is always one on ebay without the connector box, whatever that box is!
Pip
Well-known member
Just out of curiosity what are you gathering the audio to? DAW or other?
The entire signal chain has issue in the equation. Most digital systems will not be able to gather much above 21K . Certain analogue storage systems can like even vinyl, but once you get over a certain point the frequency fall off is real.
I remember reading an article about Sanken C-100 mics being recorded at high speed and then the recording being played back at normal 30ips and the sounds being used in ambient sound design for film. Can't remember what they were using to gather the audio though.
http://www.sanken-mic.com/en/product/product.cfm/3.1000400
The entire signal chain has issue in the equation. Most digital systems will not be able to gather much above 21K . Certain analogue storage systems can like even vinyl, but once you get over a certain point the frequency fall off is real.
I remember reading an article about Sanken C-100 mics being recorded at high speed and then the recording being played back at normal 30ips and the sounds being used in ambient sound design for film. Can't remember what they were using to gather the audio though.
http://www.sanken-mic.com/en/product/product.cfm/3.1000400
Pip said:
will be recording at 192khz direct to Sound devices mixpre6. it records up to 80khz according to specs.
my good old Lynx Aurora, starts to roll of at 50khz...
might borrow some different equipment! i will be demoing Sanken mic.. but i guess, i needed to have better setup to get proper results...
moamps
Well-known member
4135 is only 1/8" capsule, polarization is 200V. You need also a preamp/impedance converter and a power supply for both. Then you can connect it to a preamp.kambo said:
Bruel and Kjaer 2801 psu for the 1/8 inch cathode follower preamp and capsule ,
Roy at electrojumble.org used have 4135's and capsules although I now see his site is closed ,
Who knows maybe if you email him he might be willing to help , I believe he used the 1/8 inch capsules to measure jet engines ,so good for high frequency high Spl stuff , I believe Nasa used the 1/8 inch capsule to measure upto 140/150 db off rockets . 2801 does have a Low Z balanced out but as mentioned it probably doesnt allow the full 200khz bandwidth , for that you need to take the signal directly from the mic cathode follower output into as high z as possible 1meg or more is recomended ,1/8 inch mic/capsule circuit puts out 20volts if your hitting it with a Saturn 5 rocket afterburn .
Maybe I missed the question and answer, but what are you trying to record with that bandwidth bats?
if you wanted 200khz ,wouldnt you be wanting 400+khz sample rate ? the sensitivity of the system is proportional to the diameter of the capsule as PRR said so your probably going to end up struggling against noise if quiet things you trying to capture .
Roy at electrojumble.org used have 4135's and capsules although I now see his site is closed ,
Who knows maybe if you email him he might be willing to help , I believe he used the 1/8 inch capsules to measure jet engines ,so good for high frequency high Spl stuff , I believe Nasa used the 1/8 inch capsule to measure upto 140/150 db off rockets . 2801 does have a Low Z balanced out but as mentioned it probably doesnt allow the full 200khz bandwidth , for that you need to take the signal directly from the mic cathode follower output into as high z as possible 1meg or more is recomended ,1/8 inch mic/capsule circuit puts out 20volts if your hitting it with a Saturn 5 rocket afterburn .
Maybe I missed the question and answer, but what are you trying to record with that bandwidth bats?
if you wanted 200khz ,wouldnt you be wanting 400+khz sample rate ? the sensitivity of the system is proportional to the diameter of the capsule as PRR said so your probably going to end up struggling against noise if quiet things you trying to capture .
PRR said:
Also, what PRR didn't say but is implied in his comment, is that the larger the diameter of the capsule, the more (acoustically) sensitive it is and so the better S/N, but going against this is the fact that a larger diameter capsule becomes more "beaming" at higher frequencies (much like a tweeter becomes more beaming as frequency goes up). This is detrimental to off-axis response, and gets worse going into ultrasonic frequencies.Tubetec said:
Depending on what you're recording, the beaming (the mic becoming more directional) may be what you want, but you want to see a sensitivity vs. offset angle plot for any microphone you're considering.
we will be recording some handmade instruments in the woods / cabin ... also, bats 8)
we will have time to adjust the mic through spectrum analyser or a laptop etc!
can only record up to 80Khz with my current set up anyway!
as far as i can c, RME ADs are the cheapest option to capture full 100Khz range clean (need at least 392Khz sample rate!)
we will have time to adjust the mic through spectrum analyser or a laptop etc!
can only record up to 80Khz with my current set up anyway!
as far as i can c, RME ADs are the cheapest option to capture full 100Khz range clean (need at least 392Khz sample rate!)
> reading this! the vacuum tube triode at ultra high frequencies
And what does it teach?
(I didn't know you had any tubes in the chain anyway.)
Plain mid-1930s tubes (kin to all common audio tubes of today) can be worked at reduced gain to 3MHz-30MHz.
In audio we like a minimum number of tubes. I just simmed a reasonable-current 2-triode amp with gain of 5.8 flat -1dB to 130KHz. (Which makes it about as fast as a '741.) If I'd known you needed one, I cudda upped the current and some other tricks, -3dB @ 2.5MHz. Gain of 2, -3dB @ 8MHz. With a simple 12AT7, a good but not-great tube. Single pentode Video Amplifiers routinely gave gain over 20 out to 5MHz.
Narrow-band amps can be tuned to higher center frequencies but the band-width tends to be as above, several MHz. Notably TV IF strips, tuned for 5MC wide at 45MC, and their RF amps of lower gain but centered out to channel 13 (and beyond) with similar (less defined) bandpass.
I do not think your bats and squeaks will be ill-served by any well-chosen tube preamp (transformers are an issue if you *also* want deep bass). I don't think you need any new-fangled tubes like Acorns or Lighthouses or Pencils.
And what does it teach?
(I didn't know you had any tubes in the chain anyway.)
Plain mid-1930s tubes (kin to all common audio tubes of today) can be worked at reduced gain to 3MHz-30MHz.
In audio we like a minimum number of tubes. I just simmed a reasonable-current 2-triode amp with gain of 5.8 flat -1dB to 130KHz. (Which makes it about as fast as a '741.) If I'd known you needed one, I cudda upped the current and some other tricks, -3dB @ 2.5MHz. Gain of 2, -3dB @ 8MHz. With a simple 12AT7, a good but not-great tube. Single pentode Video Amplifiers routinely gave gain over 20 out to 5MHz.
Narrow-band amps can be tuned to higher center frequencies but the band-width tends to be as above, several MHz. Notably TV IF strips, tuned for 5MC wide at 45MC, and their RF amps of lower gain but centered out to channel 13 (and beyond) with similar (less defined) bandpass.
I do not think your bats and squeaks will be ill-served by any well-chosen tube preamp (transformers are an issue if you *also* want deep bass). I don't think you need any new-fangled tubes like Acorns or Lighthouses or Pencils.
