There are a number of affordable active crossover units out there and I am currently using the Behringer DCX2496 (Ultra Drive Pro) because it is the most affordable of the bunch and it has all of the features of a modern digital XO. There is one thing the Behringer will not do, and that is to match the input and output signals of external gear to optimum levels to minimize the noise floor.

I have been checking out the Rane RPM 26z which seems to have better specs than the Behringer and more features, including the ability to match output levels. The street price is aprox $1000 US, which is four times the price of the Behringer. So what are you getting for the money?

Well for starters each analog input and each analog output uses a two-stage gain approach. For the inputs, the first stage contains a variable gain preamp. The second stage contains a Digital Trim control located immediately after the A/D converter. The Digital Trim control should be to provide the hottest signal to the DSPs without clipping. This is the most important step when setting up gain structure. Driving the A/D converters at maximum gain can be problematic if you don’t have an accurate way to measure the input signal. For this reason, a dedicated meter displaying the signal level being passed to the DSPs is provided in each Analog Input block.

For the outputs, a two-stage gain control is also available. The first stage is a Digital Trim control located immediately before the D/A converter. The second stage is an analog trim control located immediately after the D/A converter. Attenuation is handled in the analog domain, while boosting (when the incoming digital signal is low) is handled in the digital domain. Boosting and attenuating using this two-stage approach helps maintain the RPM 26z’s excellent noise performance.

The ideal situation would be to drive your digital crossover with a digital input, bypassing the A/D conversion. In my current setup I use EAC (Exact Audio Copy software) to get my CD’s onto a hard drive without any loss of bits and from there stream the digital signal out the SPDIF channel of the computers audio card. The AES3 input has a built-in sample rate converter capable of accepting incoming sample rates up to 96 kHz. Sample rates exceeding the RPM 26z’s internal 48 kHz sample rate are automatically downsampled. Word lengths up to 24-bits are accepted.

While were at it, Rane has a useful application note on interfacing digital S/PDIF signals to AES3. I assume this would apply to the Behringer unit as well.

Thiel and company have come up with the worlds most exotic material for loudspeaker cones - diamonds. Manufactured under the brand Accuton, you can find more info here courtesy of the SpeakerGeeks search engine.

If you want to purchase a pair of the diamond tweeters they will set you back about $5,200.00 US. You can purchase from Madisound now as they are carrying the entire Accuton line, including the more affordable ceramic drivers.

There are a number of high end ’statement’ loudspeakers that are using the diamond drivers.

You can check out the Thiel web site page for diamond drivers to get a better idea of the benefits and technology.

I have run across several white papers by Floyd E. Tool that are worth reading. Follow the link for white papers that explain the audio reproduction chain from loudspeaker to room.

I have found several articles on upgrading the Behringer DCX2496 Ultra-Drive Pro crossover.

This article found on the Audio Express website is about improving the analog portion of the Behringer DCX2496 Ultra-Drive Pro crossover, in particular the output amplifier section. The DCX4296 is a low cost pro unit, so the output op amps aren’t so hot, and the use of electrolytic signal coupling caps and the use of a transistor for muting means that there is much that can be done better.

Jan Didden shows you how to do this, complete with schematics, PCB layout and response graphs. You can also get the finished PCB from Roger Pilgham Audio.

Jan shows up on this massive (108 page) thread on DIYAudio.com about the DCX2495 and how to improve / use it. Lots of tips and advice in there.

The next article by Ergo, also a member of the DIYAudio forum, is about improving the SPDIF digital inputs to work with RCA cables and consumer level SPDIF signals.

Or you could just get the Behringer SRC2496 which does sample rate conversion and jitter removal and it also works as a DAC and ADC. Street price around $120 US.

Passionate audiophiles are always looking for that magic piece of equipment, cable, loudspeaker, or audio recording that will transform their listening room into a cathedral - a sacred space where recorded music dissolves into the illusion of the original event. This is what keeps us tweaking and improving our systems - for some at a high cost. For me that magic piece of equipment is the Behringer DCX2496 electronic crossover.

I don’t have a big budget for audio and my expectations are high. I was a record producer and recording engineer from 1989-2000 and have always had high-end equipment and source material to play with. Being in the studio for the majority of my time, I did not have a home system. It may sound strange, but when I was at home I didn’t want to listen to music. This was my mindset for several years after leaving the music industry. Then something changed my life a few years ago, a simple little blog post on BoingBoing that shouted out “Thirty buck ‘toy’ amp kicking all kinds of ass”. I read about some cheap plastic battery powered 8 watt amp for $30 that a few audiophiles were raving about. This little amp was the Sonic Impact T-Amp. After reading some reviews and checking out some mods that were being done, I decided to spring the $30 USD to check it out. A few days later a package came from Parts Express. Parts Express was this new wonderland of DIY audio parts that I was not aware of before. After spending hours on the PE site, I became hooked on the idea that I could build a system on the cheap that might meet my expectations.

So now the problem was, how to use this little amp to it’s max potential. I did a lot of reading on the net and went through many different scenarios in my head. Single drivers, high efficiency, horn systems, transmission lines. Visions of sugar plums danced in my head. I knew from experience that the best sounding systems I had heard in recording studio control rooms were active systems (Genelec being my favorite). I also figured that three of these little T-Amps would equal a total of 24 watts per channel, and if I used a powered sub that the meagerly 24 watts could be put to good use outside of the power hungry band of 20-100 hz. Further more, if high efficiency drivers greater than 95 db were used, that 24 watts would give comparable output to several hundred watts normally used to drive typical low efficiency speakers.

That was the beginnings of my free-fall back into the world of audiophilia, with the end result at this point; delusions of manufacturing my own line of powered speakers, an audiophile blog, and my own system to-die-for that costs under US $1000 to put together. All from a blog post about a toy amp. Well, life is strange and obsessions can drive us to places we would not expect to end up.

So what about that magic piece of equipment, the Behringer DCX2496? Well, keep reading. Future posts will explain how to get the most out of this Swiss Army Knife processor. In my opinion, no DIY audiophile should be without a modern digital active crossover if they design their own speakers. It is the center of my system and without it I would probably not be enjoying hi-fi at this point.

Just wanted to point out these inexpensive sound diffuser panels that can be easily attached to a reflective surface, wall or celling.

From the MIO web site:

“Designed to diffuse sound, reduce acoustic glare and standing waves,
this design combines cost-effective sound control with an elegant weave
pattern. Vertical and horizontal arrangements provide improved
acoustics and superior aesthetics to any room. The lightweight recycled
paper modules can be installed temporarily with double stick tape or
permanently with wallpaper paste.”

At US $30.00 for a pack of 12 - 12″X12″ tiles, this is a steal of a deal. Compare this to other diffuser panels at prices of $20 each and you can see that you would be able to treat and entire home theater or dedicated listening room for a few hundred dollars.

I plan on ordering some of these and when I get them I will do a hands-on review.

There was some discussion on the Parts Express experts board lately regarding the nature of imaging and sound stage and how to best design loudspeakers to reproduce the sound stage.

Following are some links the came up in the SpeakerGeeks search engine that sheds some light on the issue:

General discussion of imaging and sound stage:
Decware
the Hass Effect
Thought experiment from ASC

Synthetic re-creation of the sound field via driver / cabinet design:
Ohm Walsh
Other methods are dipoles and bipoles.

Re-Creation of the sound field via blocking in-room reflections.
The Ambiophonics technique sheds much light on the subject of imaging, and in the future I expect to see many commercial systems using DSP to achieve 2 or 4 channel soundstages that are as close to the original as possible.

Review of an Ambiophonic setup.
Ambiophonics web site