Audio Technica ATM450 schematic?

[klem]

Are AT schematics pretty hard to come by? I own a pair of the 450 mics, and love their ability to take high SPL and side-address small(er) capsule. To me they are sort of like a poor man's E22s. However, I think they are severely limited by what I've noticed seems to be a trend with Audio Technica mics - the highs have a crispiness to it that you can't really EQ out. Almost like bad A/D conversion! I saw @kingkorg found a really simple mod for removing a cap from some AKGs that brought them into a much more useable / pleasant tonal balance. I'd love to see if there's a way to do something similar with the ATM 450. Seems that the first place to start is with a schematic, but I am not having much luck...

Likewise, if anyone has any experience with modding a 450 or otherwise knowledgeable about the guts of this mic, I'd love to hear them.

Thanks,

 

[kingkorg]

My approach is to measure the response of a mic both circuit and as a whole, and usually i spot the issue right there. I guess you don't have facilities to do that, and without schematic i can't tell you what might be the safe and reliable way to inject signal in order to measure the circuit response.

What i do see, and know sounds always bad is that bloody cap on top of it that causes all kinds of mess in exactly the range you are talking about. Austrian audio has this exact issue with their mics but that's just IMHO!

I see some screws there, you could try removing that part and replacing it with some kind of grille. Not hard to bend a piece into that shape. Mesh can be found on eBay. I don't know if that will fix your issue, but i an sure it will sound better, and reject bleed better.

Or maybe have someone help you make a cutout like this. I had issue with wrong cap with my Manley clone, it turned out like this.

 

[soapfoot]

Aren’t these electrets?

I wonder whether that factors into what you’re hearing

 

[klem]

Hey, thanks for smoking fast reply!
On the other hand, this is sort of a slow project that's been in the back of my head for years, but only decided to search for the schematic this morning. I am definitely an amateur when it comes to mic tinkering, and financially I'm not currently able to relegate one of these mics as a guinea pig learning tool with a good chance of damaging it by just exploring without a schematic. Heck, even with a schematic some circuits still make my head spin. But I'm hoping to learn much more as I build some more mics over the upcoming years. So that's sort of where I'm at in terms of my knowledge level, with limited resources (be it time, money, or equipment) to both tinker and explore.
I don't have the mic in front of me, and have limited images just googling, but... could you elaborate on the "cap in front"

Edit: for some strange reason the pics didn't load the first time when I saw your message @kingkorg. Nevermind, makes sense now. I imagine that would make a significant difference. I'm currently without even a drill press but hope to get some basic tooling up and running late fall this year. I have a perverse enjoyment of metalwork, even though I'm not very good at it. Maybe outsourcing is better. Would sure be interesting to do some pre-post measurements on a mod like that.

 

[klem]

Aren’t these electrets?

I wonder whether that factors into what you’re hearing

It would seem so - Audio-Technica ATM450 | RecordingHacks.com
I've generally associated electrets with lower quality output, but can't speak to the reasons why, i.e., intrinsic to the capsule or the circuit. I wonder if there's any suitable capsule that could be substituted. That would be another good way to judge how much the capsule vs circuit is playing a role in the sound.

And to be clear, I would still reach for this mic in recording drums, it's not a deal-breaker of a sound for my caliber of recordings. If money were no issue, I'd love to own 4+ e22s. I don't think that will ever be the case though where I could justify such an expense, so here's to making the best with the hand one is dealt. It's been enlightening to learn about how certain factors, e.g., price-point or projecting what most buyers might be wanting in a mic, as to why certain components are used instead of others. It doesn't seem like this mic has been explored much on this forum, yet it has a somewhat unique feature set in terms of capsule size, side address, and price point. It would be nice to build upon that.

 

[kingkorg]

I have actually done tests where i removed electret material and polarized capsule externally - no difference!

I believe the myth comes from poorly/cheaply designed/manufactured electrets. Electrets are usually used when company wants to cut corners to make less expensive product, and they don't stop with polarization.

On the other hand there are some amazing sounding electrets, like the one found in vintage Cad e100. Primo em200 as well.

You don't need any special modifications if that thing on the top is removeable. Just find some mesh to place there while you test it against stock one

 

[klem]

Well, the three bottom screws near the XLR were simple to undo, but the two screws on top are not budging, to the point of starting to strip. Possibly thread-locker on it? Not meant to be serviced or protecting from reverse engineering? I've got precision screwdrivers, but given the ease at which the the lower screws came out, something else seems to be at play other than (or in conjunction with) user-error.

 

[k brown]

DPA are some of the most highly regarded mics, and they are . . . electrets.

 

[soapfoot]

Well, the three bottom screws near the XLR were simple to undo, but the two screws on top are not budging, to the point of starting to strip. Possibly thread-locker on it? Not meant to be serviced or protecting from reverse engineering? I've got precision screwdrivers, but given the ease at which the the lower screws came out, something else seems to be at play other than (or in conjunction with) user-error.

Did you try turning the other direction?

I have no direct experience with the ATM450, but reverse screws are not unheard of on microphones (turn clockwise to sink the screw and release the part, rather than counterclockwise to remove the screw)

 

[klem]

yup, i tried clockwise just to double check, but really no movement either way, other than feeling the philips head start to slip. i hate cheap metal screws. i could drill out the screws, but not for certain the opportunity costs are worth it, no telling what else lies beneath, or if i just have a bum one... lest anyone else comes along with any success stories, i'll probably table this out of need to keep the mic functional.