[JohnR]

Here's the gated measurement of the tweeter, taken at 50cm on tweeter axis. Green = 0 deg, magenta = 30 deg, red=60 deg, blue = 90 deg. This looks a lot better than I thought it would -



Here is the same thing but taken in the rear of the panel (the 90 degree curve is the same one) -

[JohnR]

Despite the tweeter response, it seems to be much happier running higher. This is running as a full active three-way now, with crossover points at 400 Hz and 5 kHz. It's sounding pretty good.

[boone]

John, lowtech, and Danny,

I'm thinking of moving to the Neo3pdr (with back cup removed) from a pair of cheap dome tweeters that I have (set up with one firing to the rear).  I'm nervous about cutting the back cup off.  How difficult is it to remove the back cup without damage to the tweeter?  What tools work best to do this?  Any tips would be appreciated.
  Danny, in a previous post you mentioned data and pics on the use of this tweeter (especially as it relates to the backwave) and I would really appreciate it if you would post those here.
Thank you very much.

boone

[ttan98]

Hi John,

I am thinking of getting the Mini DSP, how do you find it from the point of view of:

1. Sound quality
2. Any limitations of the unit

thanks.

[Danny Richie]

I'm thinking of moving to the Neo3pdr (with back cup removed) from a pair of cheap dome tweeters that I have (set up with one firing to the rear).  I'm nervous about cutting the back cup off.  How difficult is it to remove the back cup without damage to the tweeter?

It is real easy. It will pop right off. Set the edge of the back cup on a solid table. I use the edge of my table saw. Then with a rubber mallet or the rubber handle of a hammer, just tape the top of the tweeter and the back cup will pop right off.

Danny, in a previous post you mentioned data and pics on the use of this tweeter (especially as it relates to the backwave) and I would really appreciate it if you would post those here.
Thank you very much.

Yes, you can either maintain a great back wave or destroy it depending on the opening.

The same cut out that you might use with the tweeter typically will really disrupt the response of the back wave. Here is a front and back picture of two of the baffles. The one on the left sucked, but the one on the right was great. I also tested about everything in between.

[jonners]

  How difficult is it to remove the back cup without damage to the tweeter?  What tools work best to do this?  Any tips would be appreciated.
 
boone

 I removed the back cups from mine by working a strong knife blade under the edge of the cup and levering it off. Quite easy, little risk of damage.
Just an alternative if you don't fancy Danny's method...

[JohnR]

The same cut out that you might use with the tweeter typically will really disrupt the response of the back wave. Here is a front and back picture of two of the baffles. The one on the left sucked, but the one on the right was great. I also tested about everything in between.

I posted my measurement of the tweeter from 0 to 180 up above. The back wave looks OK to me, so I'm not really sure what effect the cutout would have that's a problem - ? Mine's just a rectangular hole in a 1/2" baffle.

[JohnR]

Hi John,

I am thinking of getting the Mini DSP, how do you find it from the point of view of:

1. Sound quality
2. Any limitations of the unit

thanks.

Hi, no-one that I know of has so far been able to identify any specific sonic drawbacks due to the miniDSP...

Re limitations - the only one that I've run into is that you can only control one of them at a time. But I'm not sure what you're looking for there, as you may have something in mind when you ask that, perhaps you could be more specific?

[ttan98]

Hi, no-one that I know of has so far been able to identify any specific sonic drawbacks due to the miniDSP...

Re limitations - the only one that I've run into is that you can only control one of them at a time. But I'm not sure what you're looking for there, as you may have something in mind when you ask that, perhaps you could be more specific?

Thanks for your response, by limitations I mean what you have found so far. i am not sure whether you are familiar with the DCX2496, by reading the MiniDSP spec., it seems to include:
x-over, time alignment, parametric equalizer, very neat similar to DCX2496, these are plugs-in purchased separately? I am like you want to use it as a x-over between the twin woofers and the mid-woofer. I have a few  questions:

1. 2 way x-over  plug-in does it come with the MINIDSP or purchased  separately. . I need parametric eq. I purchased this then I also get 2-way x-over as well? If not explained.

2. What about time alignment, I cannot find the plug-in?

What plug in did you get? Thanks.

[JohnR]

Hi, I'm not familiar with the specifics of the DCX, but the miniDSP does give you crossover, PEQ, and time delay on each output (up to 7.5 ms). The way it works is that you buy a plugin that fits your application, and all of those are included with the plugin (well, no PEQ with the graphic eq plugins).

The plugins are purchased separately, they're $10 each and you just download them.

With the 2-way PEQ plugin, you have input gain, then 6 PEQ, then the xover, then 6 PEQ on each output channel, and then output gain/inversion/time delay on each output. Here's the "block diagram":



Here's the output block:



I've used the PEQ 2.1, the 2-way PEQ, and the 4-way PEQ. One limitation is that you can't set a center frequency below 20 Hz using these plugins, if you needed to do that you have to use the "Advanced" plugins and calculate the biquad coefficients some other way.

Oh - there's some noise with my laptop connected via USB, but it goes away when the USB is disconnected so it's the laptop generating it. I haven't tried using a USB charger, but I think using an external PSU is a better solution anyway, so order the (free) DC plug with it.

Hope that helps There's more details in my article on hifizine - that's the 2.1 plugin but the two-way is very similar.

I'm working on the design of the next prototype OB, which will be a 4-way (hey, I've got the crossover already! )

[ttan98]

Many thanks, your explanation is thorough.

Looks like this MiniDSP has as many features as the DCX2496.

[ttan98]

I'm working on the design of the next prototype OB, which will be a 4-way (hey, I've got the crossover already!  )

Hi John,
I thought your configuration is TMWW and you should have 3-way x-over, are you splitting up your Woofers to become 3.5(suggested by Lowtech) or 4 way?

Any comment?

[JohnR]

Hi - different drivers (Except for the Neo3). A full four-way. Or three-way + subs, depending on how you look at it.

[JohnR]

Looks like this MiniDSP has as many features as the DCX2496.

One thing to clarify, just in case. A single miniDSP board will do a two-way stereo crossover (2 in, 4 out).

To do a four-way crossover, you need two miniDSP boards (one per channel).

So it's a different set of choices than the DCX - which is stereo 3-way and... mono 6-way?

[ttan98]

Hi - different drivers (Except for the Neo3). A full four-way. Or three-way + subs, depending on how you look at it.

Looks like you are adding a sub to your open baffle ---> awesome sound, I may just follow you as I have a spare sub-woofer in hand.
Please keep us updated with your implementation. Thanks for your info.