AMTPRO-4 Air Motion Transformer

Will F

  • Jr. Member
  • Posts: 7
AMTPRO-4 Air Motion Transformer
« on: 20 May 2026, 01:00 am »
Hi,

I'm interested in building an open baffle speaker system and for the tweeter I have an AMTPRO-4 that I picked up probably 5 years ago. I will be using DSP's for crossovers, time alignment, frequency adjustments, and separate amps for each pair of drivers.

I'm wondering, How low can I go in crossing over to the midrange driver, I was thinking around 1.5K 24db/oct, but I would like to go lower if possible. Also since the driver is quite tall is this a tweeter where you can only sit in 1 spot to get all the high frequencies. If you stand up are the highs gone?

I was also thinking of making a partial diffuser about a foot behind the AMT to partially disperse the back wave, so the front wall has some of the high frequency ambience more evenly distributed.

I would be interested in other experiences regarding this driver.

Thanks,
Will

Danny Richie

Re: AMTPRO-4 Air Motion Transformer
« Reply #1 on: 20 May 2026, 01:18 pm »
Hi,

I'm interested in building an open baffle speaker system and for the tweeter I have an AMTPRO-4 that I picked up probably 5 years ago. I will be using DSP's for crossovers, time alignment, frequency adjustments, and separate amps for each pair of drivers.

I'm wondering, How low can I go in crossing over to the midrange driver, I was thinking around 1.5K 24db/oct, but I would like to go lower if possible. Also since the driver is quite tall is this a tweeter where you can only sit in 1 spot to get all the high frequencies. If you stand up are the highs gone?

I was also thinking of making a partial diffuser about a foot behind the AMT to partially disperse the back wave, so the front wall has some of the high frequency ambience more evenly distributed.

I would be interested in other experiences regarding this driver.

Thanks,
Will

I measured and tested that driver when it first came out. It had a really rough response and would not play down that low.

It is also too tall to use as a single tweeter. The beaming issue will limit listening to being right in line with it. If you move up or down from being on axis causes the whole top end to drop out.

So it will not be easy to work with.

Will F

  • Jr. Member
  • Posts: 7
Re: AMTPRO-4 Air Motion Transformer
« Reply #2 on: 20 May 2026, 09:46 pm »
Would a GR Neo3 work better. Or a pair of T26SG domes one either side of the baffle.

Is it possible to just use the front part of the Neo Wave guide, and leave it open on the back. Also the wave guide looks fairly wide. This looks like it would increase the center to center spacing thus increasing the lobing when crossing over to a midrange driver. Will the ability to cross over lower offset this.

Thanks,
Will

Danny Richie

Re: AMTPRO-4 Air Motion Transformer
« Reply #3 on: 21 May 2026, 04:18 am »
Would a GR Neo3 work better. Or a pair of T26SG domes one either side of the baffle.

Is it possible to just use the front part of the Neo Wave guide, and leave it open on the back. Also the wave guide looks fairly wide. This looks like it would increase the center to center spacing thus increasing the lobing when crossing over to a midrange driver. Will the ability to cross over lower offset this.

Thanks,
Will

The GR Neo 3 is great in an open baffle application. We use it that way in three of our designs.

There is zero lobbing issue with it. The really low crossover point makes all of that a non-issue.

Check out the vertical off axis measurements of the NX-Otica and NX-Treme models.