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Gear / Technical Help => Battery Boxes, Preamps, Mixers, ADCs, and Processors => Topic started by: TimSmith on February 07, 2012, 08:10:33 AM
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Hi all!
I've just got myself new CA-9200 and have this problem. Found this thread http://taperssection.com/index.php?topic=144168.msg1857429#msg1857429 , but it doesn't help. Lets listen to the samples. I played few notes on harmonica, so you can feel how high the level actually is. Almost the same level on all three samples.
1) CA-14 cards -> CA-9200 (+40db, volume to MAX, HPF off) -> CA cable -> sony m10 (line in)
I can hear local FM station and some noise same to the cell phone interference. Before the test I turned off all radio devices at my flat. When recording on lower levels, radio is still pretty noticable.
2) CA-14 cards -> CA ugly bbox (with fresh GP battery) -> sony m10 (mic in, high sens., level at max - 10)
There is something like wind noise in right ear. May it be because of cheap chinese battery?
3) CA-14 cards -> sony m10 (mic in, high sens., level at max - 10, plug in power ON)
Everything seems to be allright. At the end I hear some radio, but it's very low.
I've tried different mics (CA-14 omnis), different cable... Nothing helps. Even with [mics->9200->headphones] everithing is the same. Turning HPF on doesn't help either. I thought about sometimes using 9200 for home recording at high gain (well, for taping loud shows too), but for now it doesn't look like an upgrade. With this damn radio noise... Maybe I will not have these issues at a venue? I tried to take a walk on a street with gear in pocket - same.
Any ideas, guys? I would appreciate any help.
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I'm on my phone so can't listen to the samples. But, on the NMAllstars show from Moscow, I heard cell phone interference at one point.
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I'm on my phone so can't listen to the samples. But, on the NMAllstars show from Moscow, I heard cell phone interference at one point.
Yes, I remember this moment. It happened during the acoustic number. Someone sitting near me was answering the phone. But that was the only time such thing happened (already taped 4 shows with CA-14 -> bbox). With 9200 I hear radio music and noise all the time. It's like FM radio antenna - you have to move it a lot, before you catch a good sound. Same with the preamp - sometimes I can catch position of preamp/mics, when sound is almost clear, but it's very unstable... Maybe Moscow is just so anomalous place with a lot of hard radio waves??
I'm curious: does anyone has something like this with same settings?
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You are the first person to report radio interference in this forum, that I can recall. But we also don't get many contributors in Moscow ;)
I have no idea how tightly regulated FM broadcast power is in Moscow, but that could be a factor. In the US, it is very tightly regulated.
It is possible that you are near a very powerful transmission station. Such interference can be very difficult to avoid. It could also be a pirate broadcast, etc.
Maybe you could identify the specific station that is causing the interference and then try and determine the location of their transmitter? It might also be useful to conduct your test in another part of the city to determine whether the problem is specific to your location.
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I'm on my phone so can't listen to the samples. But, on the NMAllstars show from Moscow, I heard cell phone interference at one point.
Yes, I remember this moment. It happened during the acoustic number. Someone sitting near me was answering the phone. But that was the only time such thing happened (already taped 4 shows with CA-14 -> bbox). With 9200 I hear radio music and noise all the time. It's like FM radio antenna - you have to move it a lot, before you catch a good sound. Same with the preamp - sometimes I can catch position of preamp/mics, when sound is almost clear, but it's very unstable... Maybe Moscow is just so anomalous place with a lot of hard radio waves??
I'm curious: does anyone has something like this with same settings?
Dont use cheap batteries use Duracell Or Energizer. Also are you using my cables to connect the preamp? This preamp is shielded but if you get a strong enough transmitter nothing that uses unbalanced signals will be immune.
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You are the first person to report radio interference in this forum, that I can recall. But we also don't get many contributors in Moscow ;)
I have no idea how tightly regulated FM broadcast power is in Moscow, but that could be a factor. In the US, it is very tightly regulated.
It is possible that you are near a very powerful transmission station. Such interference can be very difficult to avoid. It could also be a pirate broadcast, etc.
Maybe you could identify the specific station that is causing the interference and then try and determine the location of their transmitter? It might also be useful to conduct your test in another part of the city to determine whether the problem is specific to your location.
Thank you, I will try. Very good advise.
I don't know about FM regulation, but you can expect anything in our country... ;-)
I heard some Moscow recordings successfully done with CA-9100. So maybe main concert halls are shielded enough? Don't know.
I will attend next show in march. Will do a test (keeping bbox as a back-up). And this summer I could do a test in the countryside, far from the city.
I'm on my phone so can't listen to the samples. But, on the NMAllstars show from Moscow, I heard cell phone interference at one point.
Yes, I remember this moment. It happened during the acoustic number. Someone sitting near me was answering the phone. But that was the only time such thing happened (already taped 4 shows with CA-14 -> bbox). With 9200 I hear radio music and noise all the time. It's like FM radio antenna - you have to move it a lot, before you catch a good sound. Same with the preamp - sometimes I can catch position of preamp/mics, when sound is almost clear, but it's very unstable... Maybe Moscow is just so anomalous place with a lot of hard radio waves??
I'm curious: does anyone has something like this with same settings?
Dont use cheap batteries use Duracell Or Energizer. Also are you using my cables to connect the preamp? This preamp is shielded but if you get a strong enough transmitter nothing that uses unbalanced signals will be immune.
I know about batteries. Just can't pick up good batteries at local store... I'm gonna order Maha rechargeables soon. And yes, cables are your, Chris.
About those balanced signals. I've got a feeling that I have to buy myself completely different and much more expensive equipment for that. Am I right? (sorry, not familiar)
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You are the first person to report radio interference in this forum, that I can recall. But we also don't get many contributors in Moscow ;)
I have no idea how tightly regulated FM broadcast power is in Moscow, but that could be a factor. In the US, it is very tightly regulated.
It is possible that you are near a very powerful transmission station. Such interference can be very difficult to avoid. It could also be a pirate broadcast, etc.
Maybe you could identify the specific station that is causing the interference and then try and determine the location of their transmitter? It might also be useful to conduct your test in another part of the city to determine whether the problem is specific to your location.
Thank you, I will try. Very good advise.
I don't know about FM regulation, but you can expect anything in our country... ;-)
I heard some Moscow recordings successfully done with CA-9100. So maybe main concert halls are shielded enough? Don't know.
I will attend next show in march. Will do a test (keeping bbox as a back-up). And this summer I could do a test in the countryside, far from the city.
I'm on my phone so can't listen to the samples. But, on the NMAllstars show from Moscow, I heard cell phone interference at one point.
Yes, I remember this moment. It happened during the acoustic number. Someone sitting near me was answering the phone. But that was the only time such thing happened (already taped 4 shows with CA-14 -> bbox). With 9200 I hear radio music and noise all the time. It's like FM radio antenna - you have to move it a lot, before you catch a good sound. Same with the preamp - sometimes I can catch position of preamp/mics, when sound is almost clear, but it's very unstable... Maybe Moscow is just so anomalous place with a lot of hard radio waves??
I'm curious: does anyone has something like this with same settings?
Dont use cheap batteries use Duracell Or Energizer. Also are you using my cables to connect the preamp? This preamp is shielded but if you get a strong enough transmitter nothing that uses unbalanced signals will be immune.
I know about batteries. Just can't pick up good batteries at local store... I'm gonna order Maha rechargeables soon. And yes, cables are your, Chris.
About those balanced signals. I've got a feeling that I have to buy myself completely different and much more expensive equipment for that. Am I right? (sorry, not familiar)
Every time I have had this issue with FM radio transmissions its been a crappy battery at the source of it. Or a extraordinary amount of gain. How are you connecting the preamp to your recorder please explain. Remember the gain you need for live concert recording is much less than the gain you need for acoustic recording.
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Every time I have had this issue with FM radio transmissions its been a crappy battery at the source of it. Or a extraordinary amount of gain. How are you connecting the preamp to your recorder please explain. Remember the gain you need for live concert recording is much less than the gain you need for acoustic recording.
Ok, I will get good battery if it may be the cause.
How am I connecting? Well, there is only one way, right? I plug your male-male cable (it's about 1.5 feet long) into preamp input and into recorder's line in. I don't think cable is an issue, when I plug headphones into preamp directly everything's the same.
Actually I can hear this background radio music even with +10db setting.
Anyway I need to test it more (at different places, with louder music, etc)
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Tim,
I suspect the battery box that powers your mics or a cable interconnect is not RF tight. Many designers of audio components simply forget that they have to shield their product against RF interference, but the components in their boxes refuse to ignore RF signals >:D . There are several solutions against RF susceptibility:
- use a metal case around sensitive equipment (and every device carrying mic levels *IS* sensitive).
- filter all ports that enter or leave the device so that only audio signals can leave or enter the box.
- use well shielded cable: cheap cables are often not well shielded and let RF noise leak into your recording.
It is very simple to test your setup for RF susceptibility: get yourself a (cheap) FRS radio. Switch it on and hold it within a few feet to your mics, your battery box and recorder. Press and release the PTT button and listen for clicks, pops and other strange noises. If you find any such noises, ask the manufacturer(s) about their FCC certification (in the US) or CE certification (in Europe). Another test is to switch on your cellphone near your audio equipment. Especially GSM will pinpoint devices that are not RF immune very quick.
For you manufacturers out there: check this home page http://audiosystemsgroup.com/publish.htm , especially the chapter "Hum, Buzz, and RF Interference" farther down the page. The guy who wrote that stuff was the chairman of the AES EMC committee. He is also an amateur radio operator and he knows very well how to make consumer devices work in strong RF fields.
BTW I am also experienced in EMC and RFI problems since it is part of my job as a design engineer to get the devices I design through European and US EMC certification. This knowledge helps a lot to make my audio recording setup immune against high noise levels (I record steam trains, and my recording equipment must operate properly a few feet from 15000V AC catenaries that abound with RFI...).
Greetings,
Rainer
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Russian rig "bag":
(http://pugpaw.com/Josh/img/lunchbox.jpg)
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Tim,
I suspect the battery box that powers your mics or a cable interconnect is not RF tight. Many designers of audio components simply forget that they have to shield their product against RF interference, but the components in their boxes refuse to ignore RF signals >:D . There are several solutions against RF susceptibility:
- use a metal case around sensitive equipment (and every device carrying mic levels *IS* sensitive).
- filter all ports that enter or leave the device so that only audio signals can leave or enter the box.
- use well shielded cable: cheap cables are often not well shielded and let RF noise leak into your recording.
It is very simple to test your setup for RF susceptibility: get yourself a (cheap) FRS radio. Switch it on and hold it within a few feet to your mics, your battery box and recorder. Press and release the PTT button and listen for clicks, pops and other strange noises. If you find any such noises, ask the manufacturer(s) about their FCC certification (in the US) or CE certification (in Europe). Another test is to switch on your cellphone near your audio equipment. Especially GSM will pinpoint devices that are not RF immune very quick.
For you manufacturers out there: check this home page http://audiosystemsgroup.com/publish.htm , especially the chapter "Hum, Buzz, and RF Interference" farther down the page. The guy who wrote that stuff was the chairman of the AES EMC committee. He is also an amateur radio operator and he knows very well how to make consumer devices work in strong RF fields.
BTW I am also experienced in EMC and RFI problems since it is part of my job as a design engineer to get the devices I design through European and US EMC certification. This knowledge helps a lot to make my audio recording setup immune against high noise levels (I record steam trains, and my recording equipment must operate properly a few feet from 15000V AC catenaries that abound with RFI...).
Greetings,
Rainer
The 9200 has a 100% copper shield.
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Greetings,
Rainer
Thank you for detailed answer. Highly appreciated. I will try to work something out with metal cases/boxes...
Russian rig "bag":
(http://pugpaw.com/Josh/img/lunchbox.jpg)
Lol! ;) Security may think I'm carrying a bomb. Or surgery instruments or I don't know... :)
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It is very simple to test your setup for RF susceptibility: get yourself a (cheap) FRS radio. Switch it on and hold it within a few feet to your mics, your battery box and recorder. Press and release the PTT button and listen for clicks, pops and other strange noises. If you find any such noises, ask the manufacturer(s) about their FCC certification (in the US) or CE certification (in Europe). Another test is to switch on your cellphone near your audio equipment. Especially GSM will pinpoint devices that are not RF immune very quick.
FYI: FCC certification is NOT required of electronic devices that do not wirelessly transmit signals and do not have circuits that operate at RF frequencies. Certainly there are no FCC certifications required for the manufacturers of simple preamps.
BTW, I too am an electrical engineer who has many years of experience in circuit design as it relates to rfi and emc issues.
Shielding is not a panacea. Neither is line filtering. Neither is ground isolation. Neither is any other method of rfi/emi control. Good design for prevention of susceptibility to rfi/emi will usually involve a combination of different methods, each of which plays a different role in controlling the effects of exposure to rf fields and other electromagnetic fields.
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I've got some positive results yesterday. Found that there was completely no interference on staircase in my house. I step outside the flat, close the door and that's it. I can't hear any external noise, only preamp self noise (even on +40db). Maybe that's because walls on staircase are very thick (about 1.5-2 feet) and there are only few small windows. I'm pretty sure now, that I'll be ok at concert halls/clubs.
Big thanks everyone for their help!
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I've got some positive results yesterday. Found that there was completely no interference on staircase in my house. I step outside the flat, close the door and that's it. I can't hear any external noise, only preamp self noise (even on +40db). Maybe that's because walls on staircase are very thick (about 1.5-2 feet) and there are only few small windows. I'm pretty sure now, that I'll be ok at concert halls/clubs.
Big thanks everyone for their help!
I really have had no issues with this preamp with inducted interference. Good luck with your recordings and let me know if you have any more questions.
Chris
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I've got some positive results yesterday. Found that there was completely no interference on staircase in my house. I step outside the flat, close the door and that's it. I can't hear any external noise, only preamp self noise (even on +40db). Maybe that's because walls on staircase are very thick (about 1.5-2 feet) and there are only few small windows. I'm pretty sure now, that I'll be ok at concert halls/clubs.
Big thanks everyone for their help!
I really have had no issues with this preamp with inducted interference. Good luck with your recordings and let me know if you have any more questions.
Chris
Thanks for your friendliness, Chris.
Actually there's two little questions:
1) There is a red light on CA9200. Is it supposed to turn green? I mean is it battery indicator or just on/off light?
2) What is optimal gain on CA-9200, that will give me best signal to noise ratio? I remember that you always suggest to use CA-9100 on max gain (20). How's with 9200? Or maybe I shouldn't use +30db and higher at amplified shows, only +15db (in case that preamp can be overloaded)?
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I've got some positive results yesterday. Found that there was completely no interference on staircase in my house. I step outside the flat, close the door and that's it. I can't hear any external noise, only preamp self noise (even on +40db). Maybe that's because walls on staircase are very thick (about 1.5-2 feet) and there are only few small windows. I'm pretty sure now, that I'll be ok at concert halls/clubs.
Big thanks everyone for their help!
I really have had no issues with this preamp with inducted interference. Good luck with your recordings and let me know if you have any more questions.
Chris
Thanks for your friendliness, Chris.
Actually there's two little questions:
1) There is a red light on CA9200. Is it supposed to turn green? I mean is it battery indicator or just on/off light?
2) What is optimal gain on CA-9200, that will give me best signal to noise ratio? I remember that you always suggest to use CA-9100 on max gain (20). How's with 9200? Or maybe I shouldn't use +30db and higher at amplified shows, only +15db (in case that preamp can be overloaded)?
1 - the power light is just an indicator but battery life should be about 40 + hours.
2 - The preamp is pretty quiet. So you can use up to +40 db of gain however for loud stuff I would not go more than +25 db not because the preamp will overload but because it can overload your line input.
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Ok, thanks very much!
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1) There is a red light on CA9200. Is it supposed to turn green? I mean is it battery indicator or just on/off light?
If it is red, it means the kgb are listening. If it flashes red, they are coming for you.
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1) There is a red light on CA9200. Is it supposed to turn green? I mean is it battery indicator or just on/off light?
If it is red, it means the kgb are listening. If it flashes red, they are coming for you.
Pretty usefull tool! Thanks for the tip.
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One more question (sorry :)):
With CA-9200 on high gain I hear hiss in left channel (same with bbox, only in right).
My question is about HPF. When I turn it ON, hiss disappears. Is this normal? Should I usually use HPF? Or I can get same results with EQ on PC?
Thank you!
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One more question (sorry :)):
With CA-9200 on high gain I hear hiss in left channel (same with bbox, only in right).
My question is about HPF. When I turn it ON, hiss disappears. Is this normal? Should I usually use HPF? Or I can get same results with EQ on PC?
Thank you!
You must be hearing something else. because the high pass filter will not change noise levels. And make sure all plug in power is off on the recorder. And that you are not plugged into a mic input. And that AGC is off. You dont need the HPF with my mics.
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Oh, it's been a while... Here is a short report. Over the last few months I've recorded several shows at different venues and also done tests in various parts and far from the city. And I have this "radio problem" only near my home. :-P So this problem is solved.
But recently (while recording quiet stuff) I've faced another thing. It seems to be some kind of battery issue, cos it happens with both preamp and bbox. It sounds like wind noise (bassy hiss) only in one channel (left with pre and right with bbox). With HPF turned ON on preamp it disappears COMPLETELY. I wonder what will happen if I use EQ to compensate bass reduction on 9200?? Can't do it right now and (sorry) cant post samples, i am on mobile device. But as I remember, the sample no2 from the first post can give an immpression.
And i know that i have to use good batteries. Used Duracell, but maybe it's just a copy. I plan to order Maha rechargables as soon as I can (i see many people recommend them).
And I must add that I like using my 9200 for quiet recordings (with hpf now). Makes difference when comparing to m10 internal preamp.
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Wonder why youre getting noise with the HPF OFF and no noise with the HPF ON ???
Chris? Anyone?
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Oh, it's been a while... Here is a short report. Over the last few months I've recorded several shows at different venues and also done tests in various parts and far from the city. And I have this "radio problem" only near my home. :-P So this problem is solved.
But recently (while recording quiet stuff) I've faced another thing. It seems to be some kind of battery issue, cos it happens with both preamp and bbox. It sounds like wind noise (bassy hiss) only in one channel (left with pre and right with bbox). With HPF turned ON on preamp it disappears COMPLETELY. I wonder what will happen if I use EQ to compensate bass reduction on 9200?? Can't do it right now and (sorry) cant post samples, i am on mobile device. But as I remember, the sample no2 from the first post can give an immpression.
And i know that i have to use good batteries. Used Duracell, but maybe it's just a copy. I plan to order Maha rechargables as soon as I can (i see many people recommend them).
And I must add that I like using my 9200 for quiet recordings (with hpf now). Makes difference when comparing to m10 internal preamp.
what mics are you using?
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CA-14 if memory serves me.
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Oh, it's been a while... Here is a short report. Over the last few months I've recorded several shows at different venues and also done tests in various parts and far from the city. And I have this "radio problem" only near my home. :-P So this problem is solved.
But recently (while recording quiet stuff) I've faced another thing. It seems to be some kind of battery issue, cos it happens with both preamp and bbox. It sounds like wind noise (bassy hiss) only in one channel (left with pre and right with bbox). With HPF turned ON on preamp it disappears COMPLETELY. I wonder what will happen if I use EQ to compensate bass reduction on 9200?? Can't do it right now and (sorry) cant post samples, i am on mobile device. But as I remember, the sample no2 from the first post can give an immpression.
And i know that i have to use good batteries. Used Duracell, but maybe it's just a copy. I plan to order Maha rechargables as soon as I can (i see many people recommend them).
And I must add that I like using my 9200 for quiet recordings (with hpf now). Makes difference when comparing to m10 internal preamp.
send the mics back I will check them out you might have a bad capsule.
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Yes, I use CA14 (both card & omni), but I bet mics are not the source of the noise. Ive just checked one more time to be sure: there is same noise with both mics and even WITHOUT any mics plugged in. It happens with both 9200 preamp & bbox (less noticable with bbox maybe) and without recorder (no noise with ca14->pip->m10). And yes, no noise with HPF ON on the pre.
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Yes, I use CA14 (both card & omni), but I bet mics are not the source of the noise. Ive just checked one more time to be sure: there is same noise with both mics and even WITHOUT any mics plugged in. It happens with both 9200 preamp & bbox (less noticable with bbox maybe) and without recorder (no noise with ca14->pip->m10). And yes, no noise with HPF ON on the pre.
If you are getting noise from my battery box and preamp with nothing plugged in I suspect the battery contacts are loose and or you have fake Duracell batteries and they are the source of the issue. This is Russia and if I am not mistaken there is no Duracell factory in Russia and you have an import ban on all items over $100 :) so i would wonder where these Duracell are actually coming from.
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Yeah, battery. Thats what i thought of too. Could anyone please advise good batteries on ebay?
So now I cant get any items over 100USD shipped to Russia?
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Yeah, battery. Thats what i thought of too. Could anyone please advise good batteries on ebay?
So now I cant get any items over 100USD shipped to Russia?
For sure I would say it has to be something Other than my preamp and battery box since both cant be making the same noise there is a common problem here. The only three things both pieces have is
1 the recorder.
2 the battery.
3 the mics.
If you are sure its not the mics then it can be the recorder or the battery. I recommend the Maha 9.6 volt rechargeable battery I would get a few and they work great.