Best mini cardioid condenser for DB

[Bob Branstetter]

The mount I'm using now is the second design I've done. I made the first one from spruce. It was OK, but I really wanted one that I could adjust the angle of the mic coming out of the tailpiece. My current design was made from a short length of 2" Aluminum angle stock. The mic tube is attached with the same small plastic pipe clamps that are used to attach the jack on Gage Realist pickups. They are available in most any hardware store.

Before you start, keep in mind that this modification will void your AMT warranty. It's a good idea to use the mic a while with the factory clamp so that you can be absolutely sure that you have found the best location for the mic head. In my case that spot was located directly under the end of the fingerboard and on the center seam. I keep the mic less than 1/8" from the surface. While this may seem to be an unlikely place for the mic, it enables me to get a great sound and much more usable volume before getting into feedback. I've found that the area around the ff holes is one of the worst places for the mic as it gets a boomy sound and is more prone to feedback. This may not be the best spot for you, so experiment on jobs since it will always sound great in your living room.

Removing the AMT body clamp from the tube and goose-neck can be a challenge. Thanks to Marty Paglione (the designer of the mic) at AMT, I know that you must heat all of the tiny set screws with an alcohol lamp before removing them. If they are not well heated, the threads may strip when you try to remove them because they are installed with Loctite so they won't vibrate loose. As I remember, there are 3 different size set screws. I had to go to a machine supply shop to find the smallest Allen wrench since it is smaller than any of the "standard" sizes. I can look up the sizes for you if you need to know. Once the set screws are removed, you can slide off the clamp portion. If you aren't real good a soldering small components, having a friend who is good at it will make the job a lot easier. You must cut the cable coming out of the tube housing and install a Switchcraft EN3 plug on the mount if you wish to keep the wiring to the preamp the same as it is stock. Of course you will need a EN3 jack for the cord that you cut off. They are available from several mail order electronic supply houses. You could substitute a Mini XLR plug and jack for the EN3. That will do the same job and are probably be a little more sturdy than the plastic EN3 fittings.

I attached the adaptor to the back side of my tailpiece with cap screws (Allen head). By using an Allen Wrench, I can loosen or tighten the screws (after initial installation) without removing the tailpiece again. I tapped the threads into the tailpiece so that I could partially loosen them to remove the mic mount and then reattach it as many times as I might need in the future. As it turned out, it has been permanently attached to the tailpiece for the last two years.

I'm sure there are other things that I left out, but this should give you a pretty good idea of what my mount is all about. Feel free to PM me if you have any specific questions. FWIW, I also wrote about the mount over on the TalkBass forum.

[David Powell]

At a recent rehearsal using the DPA 4021 with the AI Coda, I observed a curious behavior concerning feedback or the lack thereof. I noted earlier that I could run the channel (notch filter on) with the gain at the 9:00 o'clock position and the master at 12:00 without feedback. What I observed at a recent rehearsal (concrete floor) and confirmed at a a gig today (carpeted plywood) is that I can boost the master gain well beyond 12:00 o'clock and still not get feedback while attempting to increase the channel gain beyond the 9:00 o'clock position results in immediate feedback.

This seems odd to me, but in any case, boosting the master now allows me to get very loud with the mic and still no hint of feedback or boomy resonance. Odd, but a welcome discovery. I'm guessing the behavior is the same with other mics as well? Has anyone else experienced this?

[Bob Branstetter]

I've never tried running mine that way since I get plenty of volume with my S25B by leaving the master at "12 O'clock" and I frequently have the input level up around 11. Of course knob positions aren't really a good measure of the actual (db) output. The sensitivity of the input device (mic or pickup) can make all the difference in the world.

The AI Series III Coda manual says (on pg. 3):

"The input level controls the level of the signal at the input stage of the preamp. The master volume controls the output of the preamp (at the input of the power amp). Set the master control at "12 O'clock" and the input level at zero. The input level should then be used to control the overall output of the unit. The two controls are provided to allow independent control of the "house" volume and "stage" volume when the unit is used as a stage monitor with a connection to a house PA."

It would be interesting to see how your system responds without the notch filter on. I would assume that the notch filter would be on the preamp.

[Ken Smith]

I played last Saturday night in a club and was the 3rd gig I used my old 1970s AKG Mic wrapped in foam in the bridge legs. Would one of these new thingys you guys are talking about be better in any way or are they just smaller? I am asking because I am a bit of an old schooler and have not tried anything new other than the Shadow Underwood copy which I also like. I use that usually but in a small club or recording with an expensive English or Italian Bass that the Bridge doesn't want to be altered I have just used the Mic where volume wasn't an issue.

[David Powell]

To Bob B.'s:

Those instructions are why I had not previously tried to go beyond 12:00 on the master. In fact I can't really explain why I finally decided to push it and see what happened, just a sudden impulse I guess. The notch is definitely channel specific so it is applied to the pre-amp gain. The phase reversal function is what it is doing that is possibly the most important. I might call Rick Jones and see if he can explain the behavior. Anyway I'm kind of happy to discover that I can push it up a bit more.

Responding to Ken:

If we are getting better results from smaller mics, it is probably more because we are using them with AI amps. The notch filter and phase reversal features are critical feedback reduction measures that make a real difference. The only thing that is better about a smaller mic is that it can be mounted on the bass closer the wood, very close in fact. This gives the mic a stronger input and the large area of the bass in close proximity helps sheild the mic. Other than that, there is no reason I can think of that a smaller mic should or does work better. If you can get the big one right up on the bass, I would think it would be very similar with an AI amp.

It still feeds back before the piezo!!

[Ken Smith]

Originally Posted by David Powell

To Bob B.'s:

Those instructions are why I had not previously tried to go beyond 12:00 on the master. In fact I can't really explain why I finally decided to push it and see what happened, just a sudden impulse I guess. The notch is definitely channel specific so it is applied to the pre-amp gain. The phase reversal function is what it is doing that is possibly the most important. I might call Rick Jones and see if he can explain the behavior. Anyway I'm kind of happy to discover that I can push it up a bit more.

Responding to Ken:

If we are getting better results from smaller mics, it is probably more because we are using them with AI amps. The notch filter and phase reversal features are critical feedback reduction measures that make a real difference. The only thing that is better about a smaller mic is that it can be mounted on the bass closer the wood, very close in fact. This gives the mic a stronger input and the large area of the bass in close proximity helps sheild the mic. Other than that, there is no reason I can think of that a smaller mic should or does work better. If you can get the big one right up on the bass, I would think it would be very similar with an AI amp.

It still feeds back before the piezo!!

Ok but, I only use the AKG in a studio setting or on a smallish Trio or Duo gig where I just need a little more volume for audibility and pitch. I think the Basses I use in those settings sound fine acoustically but they are used to hearing more bass these days. The first time I did this was at a trio gig and Arnold had just finished the restoration on my Gilkes. He told me the Bass needed to be played a lot to break in again. I told him I had a trio gig and needed to cut the Bridge tabs for the Pickup. "You're gonna cut the Bridge I made for the Gilkes?" he screamed at me..lol.. "Ok ok.. I'll use a Mic".. I said to him. So, that's how I got into using the Mic again, out of fear..lol. It was in a bag of stuff in my basement that has been stored away since I retired from Playing in the late '70s. It still worked and sounds great every time I use it. In one place I play, they have an Amp there so I just use whatever Amp is convenient.

[Bob Branstetter]

Originally Posted by David Powell

To Bob B.'s:

Responding to Ken:

If we are getting better results from smaller mics, it is probably more because we are using them with AI amps. The notch filter and phase reversal features are critical feedback reduction measures that make a real difference. The only thing that is better about a smaller mic is that it can be mounted on the bass closer the wood, very close in fact. This gives the mic a stronger input and the large area of the bass in close proximity helps sheild the mic. Other than that, there is no reason I can think of that a smaller mic should or does work better. If you can get the big one right up on the bass, I would think it would be very similar with an AI amp.

I agree with some of this and have a different slant on the rest. I have the same AI Coda combo amp that David has. I think at least part of the reason that we get more mic volume before feedback is the down firing design of the AI combo amps. I only recently started using the notch filter and was still able to get plenty of volume (without the notch) in most situations without feedback.

One difference with the AMT S25B mic is that it was designed and has a preamp that is designed just for doublebass, and it has a built-in shock mount for the mic head. That has to be one of the reasons it works well. The goose neck on the AMT mic allows me to have the mic just barely not touching the top, so as David said it gets more of the wood sound. As I mentioned in a previous post, I used mics wrapped in foam rubber and stuffed in the bridge years ago myself. However, anytime you do that, you have to be deadening the top and bridge vibrations a little (at least).

[Ken Smith]

Originally Posted by Bob Branstetter

As I mentioned in a previous post, I used mics wrapped in foam rubber and stuffed in the bridge years ago myself. However, anytime you do that, you have to be deadening the top and bridge vibrations a little (at least).

Well Bob, anything that touches the Bass including a rag under the tailpiece, a bow quiver or any other mounted pickup can deaden something somehow. Every orchestra player that comes here to try out a Bass pulls out the rag I keep under the TP (for wiping the strings) as they claim it dampens the sound.

By the way, doesn't the bass touch our body when we play? Are we deadening it as well? If that is true, I deaden it now more so that I did 30 years ago..lol

The 3 Basses I have used the Mic on recently were as follows; The Gilkes with a Trio, the Loveri in the Studio and the Riccardi Storioni with a Duo. I don't think any tone loss was noticeable on those Basses as the have a bit of sound to spare..