Audio Technica PRO 70 Problem

jmayojscc

All the comments about this mic have been rosy until now. So others have this problem too, then? When I found this forum, I saw few (if any) negative comments about this mic.

Bob Holo

Yes, the edges of a port (in this case, soundhole) are high pressure and high turbulence areas acoustically... and mics do not like either high pressure or turbulence... So, if you can even get an inch or so away from the soundhole, you'll do yourself a world of good. Oh, and as is mentioned above in the thread - lowcut is important too. Suffice it to say that the surface of a guitar's soundboard is large and symmetrical enough to really play hell with the frequency response of the mic if the mic is right up on it and close to its center.

For fun - cup your hands behind your ears - then slowly move your hands away... you don't have to move your hands very far to drastically reduce how they affect your hearing. Likewise, you really don't have to move microphones very far from surfaces to drastically minimize the boundary effect. Or another way of saying this is that it's really friggin bad to put a microphone right up next to a flat object unless you know that's what you're doing and you plan to equalize the sound to remove the effect the flat surface has (you've probably all seen boundary mics sitting on stages - the sound coming from them is very colored - but in a predictable way so they can be equalized to sound natural)

... so getting the mic a couple inches from the soundhole - or better yet - getting it back up on the tailpiece a couple inches up off the soundboard... both are good ideas acoustically.

Craig Bumgarner

Bob Holo wrote:

... so getting the mic a couple inches from the soundhole - or better yet - getting it back up on the tailpiece a couple inches up off the soundboard... both are good ideas acoustically.

Yeah, that's what I've found. I've been using black sticky backed velcro to position an AT831b mic in a variety of places around the tail piece.

Using the velcro hooks and loops, I sandwich the strings between the bridge and the tail piece and then stick the mic to the up-facing sticky back. I started with pieces about 4" long, allowing some overhang beyond the strings. The adhesive is good enough by itself to stick the mic so it is easy to experiment with location. So far, the best place is about 1-1/4" below the high E string. If you fuss with the velcro, you can introduce a little upward bend which gets the mic about 1" off the top. Nice tone, minimal woofing and out of the way of the right arm which for me was a problem the the centered over the strings position. (I know, more arch in the wrist )

CB

Dr. Hall

All of this is interesting, and, of course, we have been talking about these mics for a while on this forum now. jmayojscc must have a defective mic is all I can think. I have been using an internal mic on most gigs lately, and I get great results clipping it inside the soundhole, switiching to bass-roll-off, and positioning the amp (an AER) off the floor on a chair or stand. As long as you don't need rock star volume (which my amps are not capable of producing anyway), you can get good results with this mic if you position the amp properly. We've discussed this on the forum already. Adrien Moignard et al, are getting such good results through their AER amps with these mics clipped inside the soundhole, so I can only assume that jmayojscc's mic has something wrong with it if it's humming so much. I'd exchange it and try a new one.
-Dr Hall

jmayojscc

In fact, I've already contacted the seller to start the process of exchanging.
It worked beautifully the first time, and horribly the second, in similar situations through the same PA. That suggests a problem of some kind.
Thanks!

forrestt

I just saw Jorgenson and Nolin last night and they were describing the way they cut up the hotel card and wove it through the strings, having a right angle bend in the card so that they could clip it near the bridge. John had that system rigged on his Bazouki. But they were now using a chunk of styrofoam with a sticky back and mounted it square center of the bottom half of the top of the guitar, between the end of the moustache and the bottom of the guit, on the top. The PRO 70 was inside, not sure how, I think it was pointed at the sound hole and the foam isolated the mic from the sides.

Jeff Radaich had a similar placement, without the foam, when I saw Gonzalo Bergara. They both used Roland AC-60s.

Nolin used an AER amp and Jorgenson used a Phil Jones.

Killer show, btw!

hallface

Hi folks- I'm new to this forum but had to sign up after reading about the PRO-70. I just bought one and am fighting a feedback issue. Many good comments and ideas about placement relative to the soundhole- thanks!

HOWEVER: the boominess that was experienced could be due to the fact that an acoustic guitar is really like a speaker cabinet. I play live in a band and use a Martin JC series cutaway with the Fishman pickup. Prior to using the Pro-70, I had occasionally experienced 'boominess' and 'howling' even with the guitar sitting on the stand. I popped in one of those rubber soundhole covers- problem solved. Any ambient sound can resonate in an acoustic guitar, especially if the guitar is facing monitors and the soundhole is exposed. This may be the problem! The mic is just picking that up and, well, doing its job.

I will try a number of things with the Pro-70 because the sound quality is worth it. So far, here is what has helped me:
1. Do not face a monitor speaker with the guitar soundhole directly! Experiment with monitor placement (angle away, etc.); use an in-ear monitor if necessary for yourself
2. Drop the high-EQ somewhat on the mixer- it does help
3. Play with EQ overall on the mixer- drop low and mid as well- it can help
4. The roll off on the Pro-70 helps of course
I will also try some of the suggestions listed. If necessary, I will work on a good location PLUS use a soundhole cover.

jmayojscc

I went ahead and invested in an AKG 414, and when I need volume, I just move up closer to the mic, so I haven't tried the Pro 70 in a while, and I probably won't. I also upgraded guitars just a couple of weeks ago, to an HD 28, and my volume problems have ended!

I've been thinking that our upright bass player might want to try it. It might work better on the bass, since he could clip it to his bride, which sticks out far enough away from the body that it might work well.

If any of you are interested in buying this one, (it's still clean and in the box, used maybe three times, maybe four), let me know. I bought this a few months ago through musician's friend for $98. I'll sell it for $80. I also bought a two year protection plan, but I don't know if it transfers.

James

The Los

Hi guys,

what an interesting thread. I've been thinking of picking up an Audio Technica setup for the last month. I did a gig recently where a buddy of mine used the Pro-70 through a Fishman amp and it sounded lovely; very natural.

After reading these technical issues I wonder: has anyone experienced these problems with the AT831B? Which is the other Audio Technica mic available on this site. Supposedly it solves some of the feedback issues. Just curious...

The Los

Oh, I forgot to ask... what about if you used either of these mics on a D-Hole guitar? Would the extra inches of space created by the sound hole solve or amplify the issue?