Audio Technology Projects
Copyright 2010 Troels Gravesen


I may have failed in staying cool and calm in describing the drivers presented here, but so be it. Yes, I'm freaking nuts about this small speaker, having given me a new dimension to my record collection and pointing to future projects. This is all I ask. Having built more than 200 speakers over the years, I need drivers that give me new experiences and point to new directions.
Visitors can't believe the bass these speakers can deliver, the clarity of the midrange - even at high SPLs - and the uncoloured treble. We listen to dubious tracks we usually skip, because they simply don't sound bad any more. We discover details previously hidden and musical layers being freed of congestion. Clarity!


Sept 17: After several months of service, I can still go to my system in the morning and say: This is it! The sound is as vibrant, as dynamic, as transparent as I had wanted for. I have no idea how to make a better speaker for my 25 sqm living room. The Colibri cartridge, the EAR-912 phono-line-stage, the modded GlowMaster, the Hypex bass modules, all makes the best sound I've ever had. And the cabinets are starting getting the patina I like too. Takes a year or two to get the final glow. 

AudioTechnology 3-Way Classic

What strikes the most is the amount of detail from the 15H52 midrange. It's .... whauuu! The power handling, the dynamic headroom, its dispersion, its presence quality, etc. In one way it's a demanding midrange, in another it's not. No matter what you do to it, it sounds great. The problem is in the voicing of the speaker. It's one of those speakers where you can go on and on adjusting midrange and treble level, because it always sounds great, but the trick is to get it sounding natural, to give the drivers the best possible balance, providing the correct timbre. It took a lot of records of all sorts of music to find the best balance - and the best compromise, because it's always a compromise. And it took a long time before I ordered the final crossover components from Jantzen Audio.

Yes, you can place this speaker up against the wall (I never thought I'd write this...), even close to corners, but do not have the same distance to front wall and side wall. Go to website by clicking heading or image to learn more.


Read below. What is said about the Jenzen ATS goes for the ATS-4, only even better.
The ATS-4 features a dedicated 8" bass driver for handling the 100-200 Hz range. The bass cab here delivers the bass punch of a 15 inch driver.
Also included is the top-notch ScanSpeak D2908/714000 beryllium dome.

Jenzen ATS

The most ambitious AudioTechnology project so far. Elaborate cabinet work. ScanSpeak beryllium dome tweeter.
Not cheap, but one of my few favourite speakers. The 18H52-06-13 SDKA: The best 6" midrange I've ever had.
With my new GlowMaster KT88 amplifier I play lower level than usual and still retain all details.
Run the -ATS from the best amplifiers available and it will deliver!


A classic set-up from the most powerful 10" bass driver available, a new 5" middriver with underhung voice coil and optimised rubber surround.
The venerable ScanSpeak D2905/9900 tweeter was chosen among other domes, planars and ribbons.

The PRELUDE will offer you a rock solid bass playing high or low, a fully integrated midrange and treble with some of the best treble I've had due to driver quality and the low-order filters employed. The PRELUDE will handle anything from classical guitar, vocals and trio-jazz to heavy metal. Give it some of the best 100 watts you can afford and you may even throw a Saturday evening party. Click heading or image above to read more.

Compact two-way standmount

If you think polypropylene drivers may not be able to provide the same level of transparency compared to magnesium or ceramic drivers, try these AudioTechnology midbass drivers. The old ScanSpeak 18W/8543-00 used to be the best polyprop drivers in the world - and I think it was - but these AT drivers are simply better, much better. The mineral filled polypropylene material used in AT drivers easily outperforms these more soft ancestors. Where hardcones need careful filtering to eliminate break-up nodes in the upper registers, we can get away with simple low-order filtering from this AT driver.

This is probably the most neutral sounding speaker I've ever made, and I'm sure the planar tweeter plays a major role here. The harmonics are what provide character to all instruments and voices and having an absolutely neutral sounding tweeter is part of what it takes to reproduce sound with absolute fidelity.

The ambition of this project is to offer a high-end kit that even beginners in loudspeaker building can cope with. Thus a two-way loudspeaker with state-of-the-art drivers, a fairly simple crossover and a cabinet suggestion that is easy to construct. The kit is built around some of the best drivers Danish loudspeaker industry can offer. AudioTechnology drivers are the fruit of all experiences gained by Eivind and Per Skaaaning from starting the ScanSpeak and Dynaudio companies. A modified SWANS planar tweeter delivers outstanding treble performance.

Prelude AudioTechnology 10C77 bass drivers
Initial investigation of new sandwich cone bass drivers from AT

The bass drivers shown here are meant for new 3-way constructions which will be realised over the winter 2009-10. Cabinet sketch files are piling up and maybe something like seen below will be the final result. But first, a classic 3-way set-up with all drivers in one box like the Cyclop construction will be tried. Before cutting sheets, some initial measurements on the bass driver and considerations regarding performance in a vented box, although a transmission line is the final goal for the biggest version.

Having a pair of 65 liter cabs at hand I quickly set up the bass drivers and placed the AT-SWs on top. An electronic crossover, 24 dB-LR, made it easy to find a proper point of crossover between the two units. Playing a clean fender bass from a test CD is great tool to determine the best crossover frequency and 130-150 Hz made an overall coherent sound although the AT-SWs may do even better from being e.g. 15-20 cm closer to the bass driver - at least when listening at very short distance as my workshop only allows.
Read more by clicking image or heading.