Emotiva DMC-1 Preamp/Processor and MPS-1 Multichannel Power Amplifier Manufacturer's Comment
Before this review was published, we sent a copy to AV123 to check for factual errors and offer the opportunity for a manufacturer's comment, as we always do. We received a response, and we made the recommended factual changes, but we did not immediately publish the engineer's comments, which were interwoven with the factual corrections. Normally, a manufacturer's response is structured more formally, with the corrections separated from the actual response offered for publication, and the distinction between the two is made clear. When Steve Ozmai at AV123 inquired as to why their response had not been posted, I explained the situation, and offered to post a response immediately upon receipt, to give them the opportunity to remove extraneous material not applicable to the review as published.
There has been no reply forthcoming in the three days since we made the offer. Since chatter on a few Internet forums may have left readers with the impression that we somehow avoided publishing the response, we present here AV123's pre-publication comments (Including the corrections, which were made prior to posting) together with both our offer of another opportunity for their response and clarification of certain pertinent aspects of our test-bench measurement procedures. We apologize for the confusion any of this may have caused.—Thomas J. Norton
Dear Mr. Norton,
Attached you will find our engineers' comments on the recent Emotiva MPS-1 and DMC-1 review by Steven Stone. Pease contact me directly with any questions or concerns. Thank you for your time,
Dear Mr. Norton and Mr. Stone,
Typically, Dan Laufman, the senior partner in Emotiva, would reply to you directly, but unfortunately he is out of town at the moment and unable to respond. First off, from all the guys at Emotiva, I would like to thank you for your thorough and thoughtful review of our home theater processor and amplifier.
I would next like to comment to a few items you mentioned in your review.
1. The review says: "The DMC-1 can support two independent multichannel zones in addition to a stereo output for a third 2-channel zone."
This statement is false. The DMC-1 can only support one multichannel zone in addition to a second zone with two channel audio. In the event the source material is multichannel, the DMC-1 will downmix to two channels for the second zone.
2. In regard to your measured power output of the MPS-1, I can not refute or agree with your measurements. That is, your test setup is somewhat vague in your report. Two key items are critical for me to know how to duplicate your results: 1) Was the input AC voltage source fixed at 120VAC? 2) How were you determining 1% distortion? In our labs, we fix the AC input voltage to 120V using a Variac W10MT3A autotransformer. This is essential for a consistent and repeatable measurement. If the AC line voltage sags only a few volts, the resulting power measurement will be lower than expected.
Additionally, we measure the power output using an Audio Precision System One + DSP. Attached is a power output as a function of input voltage as well as THD+N as a function of input voltage [not shown here—TJN]. The load is 4Ω non-inductive, the input AC voltage is fixed at 120VAC, the input frequency is 1kHz. It is not my intention to dispute your measurement, as I am sure your measurement is valid for your test setup. My intent is to point out how we derived our measurement, which is consistent with many other reputable companies in audio.
As I side note, I would like to point out that the EPM-300 module employs a sophisticated output limiter to virtually eliminate output clipping. The limiter itself is highly dependent on the input AC voltage. If the input voltage is 110VAC, the amplifier output voltage swing can not achieve its maximum before it flattens out (clips). The limiter senses this flatting out (clip condition) and maintains a constant output voltage swing of less than 2% THD+N. The designers at Emotiva feel that the limiter function is an invaluable feature—essentially protecting the end user from damaging their speakers. It is one of many design philosophies used to make what we consider a very robust and "forgiving" product.
Again, as my space is limited, we thank you for your review of our product and the favorable comments. Should you have any additional comments or concerns please feel to contact either Dan or myself.
We sent the following responses to AV123's Steve Ozmai:
You commented on the fact check with corrections, but did not specify that this was a formal manufacturer's response for publication. That is, the corrections, such as the one about the multizone capabilities, were made before publication, so they wouldn't normally be included in a manufacturer's response since they represent changes that were already made. We normally treat comments from the tech side as technical corrections, not as the formal manufacturer's response, unless specifically told otherwise.
If you wish to comment specifically for publication, we'll be happy to add your comments as soon as we receive them—one of the benefits of online publishing.
Also, in response to the engineer's comments, our test bench uses an Audio Precision System Two test set, and we also use a Variac to hold the input voltage at 120V. That does not guarantee the same results you get, but we are confident in the results, as we've used the same test procedure on all amps and receivers for the past five years; the measurement conditions are consistent from one review to the next.