DTC-9.4 Listening Tests and Conclusion
DTA-9.4 Sound - Putting Class-D to the Test
The DTA-9.4 is a digitally-controlled Class-D amplifier having a digitally generated control that switches a 400kHz power stage. In a Class-D amplifier, no error control is typically present or the error control is topologically equivalent to an analog-controlled class D with a DAC in front. The upswing is that the amplifer is about 90% efficient with a low amount of heat production and thus fan-less. It also saves quite a bit in the size and weight department coming in at only 39 lbs and a hair under 18" deep. The bad rap that Class-D has been getting lately has to do with the THD levels (in the case of the DTA it has a THD of 1% at rated power.) The DTA-9.4 also lacks THX certification.
So how do you tell if the DTA-9.4 Class-D solution is a decent performer? Simple - put it up against a quality Class AB/G amplifier like the Sherbourn 7/2100 . I lined up the Sherbourn and manually switched identical interconnects and speaker cables between the two units.
Editor's Note
I utilized banana connectors to easily connect and disconnect the speaker cables to the amps but wanted to point out the excellent quality speaker posts located on the back of the DTA-9.4 amplifier. They will easily handle large spade connectors as well as banana jacks or whatever else you want to throw at them. When connecting spade connectors, the plastic housing of the post keeps each cable positioned correctly to avoid slipping and shorting of the ends - a definite bonus.
As shown in my equipment list, the Yamaha DVD-S2300 MK2 was the transport and the DTC-9.4 was retained and utilized as the preprocessor. I pulled both units out into the room, making my life a bit easier and cable-switching a bit more expedient. An SPL meter allowed me to learn output volumes suitable to bring both amplifiers to the same perceived level for undergoing the listening comparison.
Listening Tests - Multichannel Audio
SACD: Norah Jones Come Away With
Me
I conducted all listening tests after recalibrating my system using the AVIA setup DVD, setting all
speakers to 75dB reference level (C-weighted). The first disc I put in was Norah Jones' Come Away With
Me, which is simply an excellent SACD to use if you want to hear vocal clarity and detail as well as
excellent room ambience and reverb. It won't excercise your subwoofer, but it will give you a great
reference point with which to compare amplifiers - which is exactly what I was doing. The DTA-9.4 held
its own and performed admirably. The differences heard between the amps were fairly subtle and I had to
go back and forth quite a few times to hear a distinction. In particular, the finger noises on the
guitar on Track 2 was a bit more pronounced and clear with the Sherbourn, but it took a lot of critical
listening to hear the difference - let alone decide if the difference was better or worse. Track 3
allowed some comparison of the bass control of each amp and both performed with too much similarity to
make a distinction. The jury is still out on this particular test for normal listening. When cranking
up the volume to near-overbearing levels, I did notice the differences became more pronounced, with the
Sherbourn allowing smoother reproduction of vocals while the DTA-9.4 tended to possess more
edge.
DVD: The Matrix Reloaded
In watching and listening to
The Matrix Reloaded
I was blown away by
Chapter 24, the Ducati motorcycle scene which ends with the head on collision and explosion of two
colliding semi trucks. There was little to no discerable difference between the 7/2100 and the DTA-9.4
in much of the movie chapters that I listened to. Both produced deep, well-controlled low end through
the M80ti speakers (again, subwoofer was disengaged during these tests). The clear observation was that
the DTA-9.4 does an excellent job of controlling detail and bass material for feature films, even at
high SPLs.
After performing several hours of comparison, I found that two things affecting the perceived performance of the Integra Class-D amplifier: high SPLs and detailed musical passages. If you are utilizing the amplifier at reasonable playback levels (under 95dB) the difference is minimal, especially on feature film soundtracks. This conclusion was reached after playing several movie sequences from DVDs including Lara Croft Tomb Raider: The Cradle of Life, The Lord of the Rings: The Two Towers and the Matrix Reloaded. On 2-channel music, the Integra amplifier exhibited less articulate bass response than the Class AB/G amp when played at higher volumes.
Overall I was impressed at the ability of the Integra digital amplifier to hold its own. There is definitely a difference in Class-D amplification, but it is a subtle difference and it is no wonder why so many companies are experimenting with this technology. Integra seems to have been more successful than most, which is why we wanted to hear it for ourselves. Integra attributes much of this success to its implementation an ingenious circuit that reduces noise caused by the transient capacitance inherent in switched MOSFET devices. The DTA-9.4's "Zero Switching Power Supply" only switches when this value is zero, resulting in a highly accurate power supply output.
Conclusions and Overall Perceptions
The Integra products have always benefited from all of the R&D that goes into the Integra Research line, but none so much (recently, anyway) as the DTC-9.4 preprocessor. This unit shares many of the features of the Integra Research RDC-7 and even benefits from its later release by having some additional features (adding component video upconversion, for example). The result is a preprocessor that is ergonomic, well-rounded and great-sounding. I noticed no major flaws with the unit and many of our suggested improvements have already been confirmed by Integra as being integrated into the next round of receivers and pre-pros coming in the future.
As shown by the Integra DTC-9.4 Processor Checklist, this unit is a good value and holds its own against pre-pros and receivers costing much more. It performs well and many valuable features that are truly useful, from IntelliVolume and the Master Volume limiter to the CHAD remote control. We have been consistently impressed by Onkyo/Integra as well as with Integra Research who seems to be constantly breaking new ground with innovative products whose technology eventually makes its way into the more affordable product lines.
Integra receivers purchased through authorized retailers or directly from Integra carry a three year warranty on parts and labor, pretty standard for this level of product. We don't expect you'll need it as Integra is one of the more reliable receiver brands available based on our member feedback.
MSRP $3000
Integra
18 Park Way
Upper Saddle River, NJ 07458
800-225-1946
www.integrahometheater.com
The Score Card
The scoring below is based on each piece of equipment doing the duty it is designed for. The numbers are weighed heavily with respect to the individual cost of each unit, thus giving a rating roughly equal to:
Performance × Price Factor/Value = Rating
Audioholics.com note: The ratings indicated below are based on subjective listening and objective testing of the product in question. The rating scale is based on performance/value ratio. If you notice better performing products in future reviews that have lower numbers in certain areas, be aware that the value factor is most likely the culprit. Other Audioholics reviewers may rate products solely based on performance, and each reviewer has his/her own system for ratings.
Audioholics Rating Scale
— Excellent
- — Very Good
- — Good
- — Fair
- — Poor
| Metric | Rating |
|---|---|
| Multi-channel Audio Performance | |
| Two-channel Audio Performance | |
| Video Processing | |
| Bass Management | |
| Build Quality | |
| Fit and Finish | |
| Ergonomics & Usability | |
| Ease of Setup | |
| Features | |
| Remote Control | |
| Performance | |
| Value |  |
