On The Road with Telarc!
RPG is proud of the improvements its products have contributed to modern recording studio design. What we often neglect to mention is the success RPG has brought to engineers in the field. Often remote recordings are made with make-shift control rooms and less-than-ideal acoustical conditions in the performance space. We are especially proud of our collaboration with Jack Renner and Mike Bishop of Telarc and Tom Jung of dmp, with whom we have closely collaborated over many years. Mike Bishop had previously reported on his experiences with RPG on the Come, Gentle Night, Telarc CD-80556 (Telarc DSD Session in Baltimore, Maryland) recording of the Ensemble Galilei. This month Mike Bishop describes how he utilized RPG to help with the acoustics on a new CD by Jim Hall due for September release.

RPG on the Road
Grand Slam, Live at the Regattabar (Telarc CD-83485)
Jim Hall, guitar
Joe Lovano, tenor, soprano, alto sax, clarinet
George Mraz, bass
Lewis Nash, drums
Produced by John Snyder
Recording Engineer: Michael Bishop
Live Sound Mixer & Engineer: John Servies
Technical Assitants: James Yates, Mike Ely

"Grand Slam is the name of the group legendary jazz guitarist, Jim Hall and sax great, Joe Lovano put together with bassist George Mraz and drummer Lewis Nash. Telarc recorded the project 'live' at the Regattabar, the well-known jazz club at The Charles Hotel of Cambridge, Massachusetts on January 20 - 22, 2000. Initially being released on CD, the sessions were recorded direct to 2-track stereo Direct Stream Digital (DSD) and 6-track DSD surround for release later this year on Super Audio CD.

The performance area of the Regattabar has some particularily difficult acoustic problems caused by very low ceilings, carpeted walls, and very little available floor space. Prior to going to the Regattabar, I had heard from the musicians that we would have a hard time recording there because they have had trouble hearing themselves there in performances in the past. I had the Telarc truck packed with every RPG Diffusor we possessed for possible use on-stage. I have had great success making good performance / recording areas on difficult stages with the RPG materials in the past, so I had a pretty good idea of what I could do at the Regattabar. Using combinations of the RPG 2x4 and 4x4 Diffusors, I lined the back and side walls of the tiny performance area at the Regattabar. I used three sets of RPG panels to form a space for Lewis Nash's drums, and further extended 'wings' of Diffusors to the side of the stage-area, all to even-out the frequency response of the area and help focus the sound toward the microphones. I was using a Neumann KU100 Binaural Head for the overall stage pick-up, so I really needed the sound on-stage to have a natural-sounding balance and openness that did not exist there without treatment. I did not want to rely only on close-mic'ing techniques to overcome the stage acoustic problems and therefor have to impose artificial ambience from a reverb device. I also wanted to improve the performance conditions for the musicians - this was a live recording and I wanted the stage 'vibe' to be as good and tight as possible.

Lewis Nash (drums) was the first to notice the improvement. He was able to play far lighter than he previously could in that space. He felt he was now getting a really good balance between cymbals and drums without the excessive 'boom' he had experienced there before. He also remarked that the cymbals sounded much more 'open' to him now. Lewis was very happy with how his drums were represented in the recording during playbacks. Since the sound recorded was primarily picked-up by the Neumann head, I can only attribute the good results to the improvements made possible with the RPG Diffusors.

Joe Lovano (sax) also noticed a dramatic improvement on-stage. In the past he had a lot of what he called 'upper-low-end honk' on-stage that he didn't feel was natural. That effect was completely gone now. Joe also remarked that he could actually hear the other musicians now, which he couldn't do well in the past. There are no stage monitors employed on the tiny stage.

I had to use a typical, very small hotel room at The Charles for my control room. In that room, we had a 24-channel console, surround and stereo monitoring, 2-track DSD system, 2-track PCM system, 6-track DSD system, and 6-track PCM system, and video monitor to the stage. The control room had quite a closed-in sound to it - not exactly conducive to accurate monitoring.

With no real space to spare, we managed to squeeze-in a few RPG Abflectors™ and a couple of BAD™ Panels, which helped even-out the response of the dead room. After the first night of recording, Regattabar live sound mixer, John Servies, invited me over to his apartment where we had the opportunity to audition the first night's work through his Dunlavy monitor system. Listening through a great high-resolution system such as John's confirmed that the balances we got the night before were working just fine with some very minor changes on-stage. Our makeshift control room/hotel room was working just great.

The improvements made possible with the use of the Diffusors on-stage at Regattabar made for a very natural, open live performance experience captured to DSD. I feel that, without those valuable tools, we would have been able to use only close-microphone techniques, which just wouldn't allow the great performances to 'breathe' and be as enjoyable to listen to as they are on this CD. Hauling a truck-load of RPG Diffusors, Abffusors®, Abflectors™, and BAD™ Panels with us on almost every session is quite difficult - but certainly worth the effort in the dramatic improvements we have made in some very difficult acoustic spaces. The results can be heard on many of the Telarc CDs and SACDs. Just look on our Technical Information page for indication of where we use the RPG materials in-session."

Dr. Peter D'Antonio Fellowship Announcement
RPG President/CEO Dr. Peter D'Antonio has been elected a Fellow of the Acoustical Society of America. Announcement of the election and presentation of the Fellowship certificate will be made during the plenary session at the Newport Beach, California meeting of the Acoustical Society of America December 4-8, 2000. The citation reads "For contributions to the applications of sound diffusion from architectural surfaces". We invite you all to attend.

New QRD Scattering Coefficient Data
The first 100 years, since the founding of architectural acoustics, was devoted to standardizing absorptive materials. Today, two independent working groups are considering ways to measure and characterizing scattering surfaces. The AES SC-04-02 working group is proposing a 2D and 3D measurement technique to evaluate the uniformity of diffusion. The circular autocorrelation of the 1/3-octave polar responses is used to form a diffusion coefficient, bound between 0 and 1. The ISO/TC 43/SC2/ WG25 is studying a method to evaluate the random incidence scattering coefficient. This is obtained by a comparison of the reverberation times, obtained from phase-locked average integrated impulse responses, for a stationary and rotating sample in a reverberation chamber. We present the first results for both the diffusion coefficient and the scattering coefficient for a QRD® 734.

RPG Acoustical Foam Finds Widespread Acceptance in Pro Audio Applications
RPG ProFoam™ and ProCorner™ have re-defined the shape and performance of acoustical foam. RPG ProFoam™ and ProCorner™ products are beginning to replace convoluted foam products in many Pro Audio and Home Theater applications. ProFoam™ is the first patented nested foam technology and overcomes the three shortcomings of conventional convoluted foam. ProFoam™ offers a new curvilinear appearance, contrasting with the "dated" convoluted foam appearance for a more architectural appearance. ProFoam™ is the only nestable foam, which means you can always add additional layers of foam at a later date for added absorption. Lastly, ProFoam™ utilizes an optimized surface topology that mounts most of the acoustical foam away from the mounting surface. With conventional acoustical foam, a significant portion of the foam is located on the surface where the particle velocity is zero and absorption efficiency is minimal. Ask for ProFoam™ and ProCorners™ at your favorite Pro Audio outlet.

RPG Offers Boundary Element Optimization Service
The power of boundary element scattering predictions is well known in many parts of the acoustics industry. However, because of the high cost of commercial boundary element programs, acousticians involved with architectural acoustics have not benefitted from this technique. RPG has developed a powerful boundary element capability that can evaluate potential stage canopies, acoustical shells or wall shaping as well as optimize shape motifs provided by the client or the architect. RPG provides this service through its Collaborative Holistic Acoustical Optimization Service, CHAOS. Today several facilities have benefitted from this design capability and we invite you to evaluate this design approach on your next project.

Contrasting Diffusors
Reproduced Sound 16
17-19 Nov 2000, Stratford Upon Avon
Organiser: Institute of Acoustics, UK

Trevor J. Cox
Department of Acoustics and Audio Engineering
University of Salford, Salford, M5 4WT,UK.
t.j.cox@acoustics.salford.ac.uk

Peter D'Antonio
RPG Diffusor Systems Inc.
651-C Commerce Drive, Upper Marlboro, 20774, USA
pdantonio@rpginc.com

Abstract
Since the pioneering work of Schroeder in the 1970s, many innovative diffuser designs have been produced and used in a wide variety of reproduced sound applications. Diffusers have been formed from a wide variety of rough surfaces. To take two examples, there are the profiled wells of Schroeder diffusers and the smooth curves formed using optimisation. Diffusion can also be created by variable impedance, such as those formed from MLS sequences. In this paper different methods for creating diffusion and types of diffusers will be compared and contrasted. Both the acoustic performance and non-acoustic aspects of the designs will be presented and discussed.

RPG Announces Topakustik and Topperfo Absorptive Wood System
In a continuing effort to broaden the acoustical palette, RPG now announces a major new product line of decorative absorptive wood systems.

The product line consists of TOPAKUSTIK, an attractive and durable perforated wooden panel or plank system with a parallel-grooved facia and TOPPERFO, a wooden panel with a regular array of holes ranging from 1 mm to 8 mm.

Topakustiks is available in a mid-high (M) and also a low-mid frequency (T) system. This allows two different absorption characteristics for a wide range of absorption options with the same visual appearance.

The mid-high M system achieves absorption over a wide range of frequencies by utilizing a range of hold diameters, spacings and air cavity depths. A typical 5/3M system consists of a 5 mm wide flat reflective area and a 3 mm wide slot. The panel is perforated with a 12 mm diameter hole with an open area of 12%.

The low-mid T system utilized dual diameter holes. The same 5/3T system consists of a 5 mm wide reflective section, a 3 mm wide slot, a 3 mm hole at the face (for pleasing appearance), expanding into a 12 mm hole through the rest of the panel. Thus the 5/3T system offers open areas of 3 and 31%.

The TOPPERFO system is also available in a mid-high frequency M system and a low-mid T system. The M system offers a single diameter hole ranging in diameter from 3 to 8 mm on 16 mm centers. The 16/16/6 M system consists of 6 mm holes on 16 mm centers with a percent open area of 11%. The 16/16/12-3 T system consists of dual diameter holes of 3 mm at the face and 12 mm at the rear offering 2.8 and 44.1% open area.

The core is fire-rated MDF or non-combustible gypsum. Standard veneers are offered and special veneers are available on order. Topakustik is available in panels up to 1200 mm and planks of 128 mm width. Various lenghts are available. Topperfo is available in a wide variety of panel sizes. Standard thickness is 17 mm with 19 mm thicknesses available for extra heavy duty applications, like gymnasiums.

RPG To Distribute For Lake Technology
Lake Technology is a high technology company based in Sydney, Australia. Lake has more than 40 patents and patent applications pending in digital signal processing (DSP), 1-bit signal processing, digital communications technology, video games, internet media and related product areas. The company commercializes its innovations via proprietary products and licensing and has one of the world's leading research and development teams in audio and DSP at its Sydney research laboratories.The company originated the technology behind 'Dolby Headphone' a system for providing cinema-quality surround sound over ordinary headphones.

RPG is proud to announce its appointment by Lake Technology as a distributor of its line of convolution hardware to the architectural acoustics industry. The range includes the CP4 and Huron convolution platforms.

The CP4 is an affordable real time convolver with zero latency, meaning that once you have downloaded an experimental impulse response or a SIM file from CATT Acoustics you can instantly audition the room with any sound source in real time, for as long as you like.

The Huron system is the big brother of the CP4, allowing more complex interactive audio simulations including walk-troughs. "The CP4 and Huron systems are powerful tools which are seeing an increasing use in the architectural market. We are very delighted to have RPG as a distributor in the US, they have an excellent global reputation", said Patrick Flanagan, Sales Manager for the Huron and CP4. Dr. Peter D'Antonio, President of RPG, indicated that "RPG is significantly expanding its Digital Acoustical Palette and is very excited to add Lake Technology to its growing list of digital products. The Lake technology is a natural extension of our collaboration with CATT Acoustics and offers the architectural acoustics community complete auralization capability."

Diffuse Seminars
RPG is now offering regular educational Diffuse Seminars for acousticians, sound contractors, home theater system integrators, architects, and other specifying consultants to apprise the industry of our research, new products, application assistance, and an introduction to RPG's new Room Optimizer™, Shape Optimizer, and CATT Acoustics software. The press is also welcome. RPG is applying for AIA Continuing Education credits.

The response to these educational seminars has been very enthusiastic. The July seminar was well attended. We had a interesting mixture of acousticians, architects, an audiologist, and RPG reps. The seminar dates for 2000 are now available.

If you are interested in attending, please e-mail to info@rpginc.com, contact your local rep or call Jeff Angel at 301-249-0044.

RPG Factory Summer Shutdown
This year RPG will close its production facility during the week of August 14-20th. We announce this early so that all of our specifiers, clients and representatives can plan their orders and deliveries accordingly.