For question #1, according to testing done by Engineering, you should keep this duration <0.8 seconds for voltage dips between 60% and 100% of full mains voltage (tested at 120V, 1/8th power, pink noise), although audio will most likely dropout briefly. Since the PM8500/N is so highly tuned to the mains, and with the nature of program material, any drop in power between 8 msec and 800 msec could result in loss of audio. Demands greater than 1/8 power will result in a worse situation (dropouts, shutdown).
Please note that these are typical numbers and not guaranteed.
For your question #2, I am checking with Engineering now and will update this thread.
Hi Kakudo, Regarding the fan on the PM8500 and PM8500N, we do not have a recommended replacement interval for the fan.
This particular fan was carefully chosen to provide a long life for use with PowerMatch amplifiers. Additionally, the same fan is used in Bose automotive applications where the conditions can be quite poor (thermal/humidity). Test results from accelerated life testing under various orientations, temperatures and max fan RPM indicates a life span approaching the 5-year warranty of the product. Under normal conditions (less than max RPM), we can expect a life span greater than the warranty period.
I’m Kakudo. Thank you for reply. It would be nice we can say the fans in the PM would have been working for at least 5 years. By the way, is it possible that these fans be replaced by our Repair Center.
Hi Kakudo, so sorry for the misspelled name! I wish to blame my Mac's spellcheck function but I cannot. My apologies.
As you are aware, for the 1st 12 months, a failed PowerMatch amplifier must be returned to Corporate Quality engineering per the rapid response program, and the customer is sent a new product ASAP. After that, authorized service centers will have the ability to repair the product using service parts. The 3 fans in the units are indeed service parts and can be replaced after the rapid response period. Thanks for the question.
We have asked additional information on the specification of PM8500. So could you provide me them?
3. The list of all alarm messages users can see on Alert Panel of CSD monitor window and these descriptions. I know there is a list on it in P38 of Users Guide for PM8500 but I think it has limited information. It would be better that contents of alarm message in this list were written in actual text on Alert Panel such as “User Warning: AC loss detected” or “User Warning: AC returned”.
4. How much in degrees does internal temperature of PM8500N releases high temperature alert?
Kakudo, Today I have reviewed the alert list in the PM8500 User Guide and discussed your questions with Engineering. I would like to get some further clarification so that we are providing useful information to you (and in a revised User Guide):
3. For the alarm list, we can defintely do a better job in listing the actual text. You make a good point. I am hesitent to describe all messages as some are very much internal focused (power supply, DSP, etc) and the hope is that customers never see these. If they do, a service call is in order. Perhaps we simply state that error messages not shown in the list should be reported to service personnel for resolution. Will we satisfy your needs by a)showing the actual text and b)showing more alarm messages applicable to user-resolution?
4. For this question, can you help us understand how the customer will use this information? What reference does the customer have for thermal monitoring of electrical components? In our specs we state an operating range of 0 °C - 40 °C which should satisfy most useful operating conditions (1/3rd power). Could you explain what the customer is looking for? Are they wanting to understand what the thermal margin is before gain reduction is induced by the amplifier protection circuit?
Thank you for reply. Please let me input my opinion on these topics to you.
3. I also think that user can’t resolve most troubles which you have not stated in the Alarm list in current UG. But if users would know PM8500N can make a diagnosis on itself about many issues they would understand high reliability of PM8500N.
4. They just want to know to be relieved. For instance, they are a little bit anxious about filter-less ventilation of PM8500N because dust can enter the inside of PM8500. If internal temperature of PM8500 could be very high dust could catch fire.
I'd like to answer your number 4 question, about dust and temperature. I am extremely confident in the performance of the PM8500 amplifier in dusty environments, and will share why in a way that I hope will help you speak to customers. There are a few parts to the answer.
Our thermal design, airflow, and firmware protection keep all internal temperatures well below the flammability level of any common dust, under any conditions, including for example, if one or more fans stopped working. That is not an issue.
There is more to the story as well. We performed dust testing in a laboratory to measure our thermal performance over the life of the PM8500 in a dusty environment. This laboratory has the capability of using different dusts and concentrations in the air to simulate the dust level of different environments.
Over a ten - year simulated life of the product in dust, we saw negligible increase in thermal measurements in the chassis, and had zero events of thermal limiting or failures. When we tore down the unit for analysis there was no dust penetration of fan bearings, and no penetration of the area between the output FETs and the heatsink.
We also tested with dust combined with high humidity, with the same results.
I am not aware of any other amplifier manufacturers that have performed these types of test.
The reasons for that excellent performance include:
The power and amplifier PCBs are purposefully oriented in the chassis so dust will not accumulate on the high voltage and high thermal conduction areas.
The airflow is sufficient to move much of the dust through the unit, so while there is some accumulation of dust on the components (e.g. heatsinks)it is not as much as one might expect.
The venting on the front of the unit is designed to trap larger aggregates of dust (like hair, etc. - called "dust bunnies" in the U.S. ) and acts like a filter for those particles.
The airflow and fan keep the interior relatively clean without a filter
High quality fans and careful design of the heatsink and thermal interface material to stringent dimensional tolerances provide barriers to the penetration of dust.
We took yet another step to test the common understanding in the industry that an extra filter can help performance. We repeated the dust test with an added filter mounted to the front of the chassis, of the type commonly used in power amplifiers . We found that it provided no benefit over our present system, and is therefore unnecessary. As you know, the danger of a filter is that if the pores are too fine or it is not cleaned on a regular schedule it can get clogged, which can restrict the airflow and hurt performance.
If the front and rear panels are kept clean the amplifier will work very well, and will maintain 1/3rd power even at 40 degrees ambient temperature.
I am very pleased that we have been able to collect data to show the robustness of our amplifier to dust in the environment. I love to tell this story, and I hope it is helpful!