Audio Technica says electrets don't lose their charge?

G

Guardian

New member
I emailed Audio Technica because the pair of AT3528's I bought during the summer have a very low output level..I have to crank the gain all the way, with the fader at U, on my Mackie 32*8, to get them peaking around 0db, when used as drum overheads.....They told me the mics were designed to not be very 'hot', and should be about the same as an SM57 <I tested, the 57's are hotter>
..and that

"Modern electrets are incredibly stable and do not lose their charge over
time. A well designed electret can easily out perform an externally biased
condenser."

I find that hard to believe....anyone have any thoughts?
 
Hi Guardian,

Gee, I find that hard to believe what Audio-Technica told you about their AT3528s--they should be quite a bit louder than an SM-57 would be [being a condenser type versus dynamic]? Weird! Try the AKG "Blue Line" C 391B pencil out for size. They sound quite amazing! I might get two of these mics because you can change the different polar pattern capsules around. It comes with a standard cardioid but I want to get an omni and figure-eight head for versatility too.:cool:
 
here's the reply they gave..

Unfortunately I don't know what you are using for a signal source to do your test, however I do know that the AT3528s are not super "hot" microphones. They were designed in response to professional live sound engineers who were complaining that our 40series condenser mics were overloading their consoles. We set the sensitivity to approximately 3mV/Pa which is roughly twice that of the Shure SM58 which has been an industry standard for live sound.

Please compare the AT3528 to your SM57 or 58 and let me know what you find.
If you don't have an SM57/58 compare them to any typical dynamic mic. They should be similar in output level.

Modern electrets are incredibly stable and do not lose their charge over time. A well designed electret can easily out perform an externally biased condenser.

-----------

That sounds really hard to believe, from what I know...I bought the 3528's back before I knew that electret condensers lost their charge over time..or thought I knew..according to this person at Audio Technica, they dont....If I had known then, I would have bought 2 Rode NT3s instead..I have a pair now, and they are good all purpose mics..I bought the 3528's for budget drum overheads, because they have a natrually bright sound which would emphasize the cymbals..which is what I tend to use the overheads for, as well as a stereo capture of the kit in general..but I noticed pretty quickly that I had to crank the gain on them all the way, with the fader on my 32*8 @ unity, to get peaks at 0db..I thought it was just the mic..but then I found out that electrets lose their charge over time, and said..ah ha..that's why they're not very sensitive..and I figured they were just 'old'..and it was too late to return them, so I figured I would just keep using them for overheads and/or mic a snare just for fun, and if the drummer whacks it, who cares, because it's dying anyhow..but then I figured well, they're under warranty, so I'll see what the AT people have to say...
 
I know that Audio Technica just recently discontinued this whole series of mics; the 3525, 3527, 3528. Maybe they were made cheaply and didn't sell that well?:eek:
 
All electrets, regardless of manufacturer, will lose their charge over time, and will therefore suffer from decreased output as they age. Some will age much more slowly, and it will take many years to detect the change. Some will give up within just a couple of years. But all will eventually have their charge migrate away: that's a simple physical truth. Those trapped electrons want to _leave_, and entropy always wins. Even for the best of them, eventually enough gamma rays will happen along to disturb the trapped charge. Even sooner, if you like up here at high altitude like me!

A really good electret can stay healthy for an amazingly long time: but long does *not* equal forever.

Sorry, Mr. Audio-Technica support dude, but your mics aren't immortal. There are a lot of them that are very nice mics: but get back to us in 20 years and we'll show you the degradation of output.
 
I can't believe I am defending electrets but there have been some amazing developments in the last few years in stabalizing electret materials and new methods of charging the material. Some of the thicker electret materials are predicted as having insignificant charge deterioration for 35,000 years.

The main problem with new electret mics is that the material used is only about 1/100th of these new materials, and that tensioning and basic design still control how the final mic will sound. All 1" condenser mics will have a resonance in the 5 to 6kHz range - how that resonance is shaped by the manufacturer is more important, at least to me.

High output condenser mics will always require some pretty high voltages if they are to avoid clipping the signal peaks of loud sources. 1-1/2V AA batteries (even 9 volt batteries) can't always cut it on loud signals.

Assuming the best of materials used, I think worst case deterioration of the charge over 20 years might be around 3 dB, which is quite acceptable to me. I'm more concerned about the design of the electronics and the basic capsule design at this point.

I hope it doesn't turn in to another marketing phrase, like "Made from space age polymers", which is a fancy way of saying it's made outta cheap plastic.
 
I know you have probably done this but make sure you have the gain set correctly
on the back of your mackie, Also check to see if you havnt blown a couple of channels
on your board.
I have the 8 buss 24 and had a channel blow and had to turn everything up like you
do on yours.
Just a thought.
 
PinkStrat, I have an Audio-Technica 3527 (omni), and it sounds
quite nice for vocals. It's used when I record acapella quartets.
They are also supposed to sound excellent for acoustic guitar.
Due to low sales, however, they were discontinued.
for vocals it should be rated higher than a Rode NT1, and lower
than a Studio Projects C1.
 
Hi chessparov,

I honestly thought that the 3527-3528 was discontinued due to low sales [than from my comment about this mic possibly being more cheaply made] That particular Audio Technica series was also designed to be "more affordable"for home studio folks just starting out too! I, too, had throughly tested the AT3527 on acoustic guitar and it worked okay. I am going to order the omni-directional capsule for the AKG C 391B and see how it works with Harvey's "over the shoulder" acoustic miking technique [and vocals too]. Will give you the full report soon!:)
 
hmm

Is there a seperate gain control I dont know about? I was talking about the 'main' gain :) control..the 'trim', I guess I should have said..and leaving the fader @ Unity..doing the whole Mackie recommended way of setting the levels..fader @ U, adjust trim until peaks around 0db..

I just paraphrased Harvey to the Audio Technica person, who asked where I heard 1/2db per year (I read that in an earlier Harvey Post <tm>), so I just said an audio-tech guy I know said that the older electrets had that tendency, whereas the 'newer' ones will probably lose about 3db over 20 years..

Let's see what they have to say..they also asked if I had the -10db pad engaged, which I don't..<duh>, so..hmm
 
The 1/2dB per year came from Shure's AES paper on the design of the SM-81, their first electret mic. This figure was their aging estimate, based on their testing of electret material at the time.
 
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