Speakercraft MCZ88 problems

[PGG76116]

Can anyone make some suggestions to me on what else to try? We have had a system installed with the main receiver being a Speakercraft MCZ88 their control key pads and speakers. It was installed by a guy I know who has done many of these in the past with the exact same units used. We are now waiting on the replacement of the third MCZ88 in two months. The first one died after about two weeks and we were told Speakercraft said it had a bunch of blown fuses inside. The second and third units just stopped having sound #2 lasted about 10 days and #3 lasted about 3-4 days. The installer has us with sound using a temporary back up Harmon Kardon but not being able to change cable stations without going into the electronics closet and just pure frustration is killing us. They have run many test ie OHM rating on each speaker, a speaker, keypad and wire continuity test as well as each key pad. We have a APC1500 battery back up and surge protector and had a electrician install a dedicated power line to the closet. The closet gets warm but not hot and is well ventilated. What else can we try, test or check? We have been using a ipod most of the time for our source and the last time it worked until I turned it off then the next morning the sound was dead. I am going nuts any help would be really appreciated. Thank you in advance. PGG

 

[PGG76116]

Latest from Speakercraft

They sent below my installer this today by email it chaps me hard since they dont suggest a "device" to cure the suposed problem. Is this a common problem to burn up units when voltage gets in the 110-112 range? Thanks PG

Battery back-up is not what we're looking for. That would protect in
the event of a power outage. We're mostly concerned with dipping line
voltage - we have seen problems specifically with line voltage that
dips down to the 110-112 volt range. A device that keeps the line
voltage steady at or near 120 is what we're looking for.

 

[MDS]

They're talking about automatic voltage regulation and most UPS offer voltage regulation. The regulation is within a narrow band so it is not possible to tell it to keep the voltage at exactly 120v.

For example, my APC UPS for my computers is currently set to an upper limit of 138 volts and a lower limit of 88 volts. If it falls outside that range, it adjusts the voltage back to 120 but of course it will constantly change. See if your battery backup offers a similar range and increase the lower limit to above 110v and see if that helps.

 

[TLS Guy]

They sent below my installer this today by email it chaps me hard since they dont suggest a "device" to cure the suposed problem. Is this a common problem to burn up units when voltage gets in the 110-112 range? Thanks PG

Battery back-up is not what we're looking for. That would protect in
the event of a power outage. We're mostly concerned with dipping line
voltage - we have seen problems specifically with line voltage that
dips down to the 110-112 volt range. A device that keeps the line
voltage steady at or near 120 is what we're looking for.

Oh dear, where to start?

First of all that APC 1500 is not the problem. I have two of them and they will support voltage in 1 to 5 msec. So forget that as the problem.

With three units having failed then there is something wrong with your installation and or application.

I have pulled the 50 page manual on that unit off line.

First ventilation. It states that the unit must be on top of all other units, and if installed in a closet there has to be forced air extraction.

I need very great detail about your speakers and how they are wired. There may be a serious installation error, which on a forum can only be analyzed with great detail about your installation.

Now those units are very much in the nature of background units.

They contain 16, 50 watt amplifiers. However the max power draw of the unit is 275 watts.

The unit is specified to give 50 watts to 8 ohms, or 70 watts to four ohm loads, only two channels driven. This would give a conversion efficiency of 50%, which would be fairly typical. So you have only 135 audio watts to divide between 16 channels, which is about 8 watts per speaker channel if all are driven. Actually I see looking at the manual, the amps give 1/8 rated power all channels driven, which is 6.25 watts per channel.

It states in the manual, that this unit is not intended for high power application.

If you want to have more than one room playing at more then low background volume, then external amps are required for each channel driven from the preouts. That will get very expensive.

I'm certain you will have another unit blow, if the installation and use is as you have it now.

So to help you further I need to know precise details of the installation, especially wiring details, speaker specifications, speaker numbers and details of any room controls. I need to know how many of the sixteen amp channels are in use.

I also need details of how you have used this unit and intend to use it.

 

[PGG76116]

Much thanks

TLS guy and MDS thank you very much for your thoughts I will try to get more details to you and will give this information to my installer to make sure he has checked it all. Thanks PG

 

[PGG76116]

TLS guy

I from you post feel asking the system for too much power might be the problem. I do want to ask you however the last time we had a MCZ 88 fail we used it until we were ready for bed and I turned the unit off at a Mode panel. Then the next morning it had no sound when turned on. does this sound strange to you? To be working fine turned off then to have failed overnight if over taxing its power was the problem? Thank you again. PG

 

[TLS Guy]

I from you post feel asking the system for too much power might be the problem. I do want to ask you however the last time we had a MCZ 88 fail we used it until we were ready for bed and I turned the unit off at a Mode panel. Then the next morning it had no sound when turned on. does this sound strange to you? To be working fine turned off then to have failed overnight if over taxing its power was the problem? Thank you again. PG

Solid state equipment is fickle. It likely did not fail overnight, but with the in rush current of the power up.

In the meantime, you could post exactly how you are using this thing, and what you expect of it.

If you are thinking you can watch movies at reference levels with this device, it is not for you.

In all honesty it is the type of device I would run a mile from, miles in fact.

 

[PGG76116]

Too late to run from it

It is too late to run from but thank you for you thoughts regardless. We use it mostly for whole house sound during entertaining that's about it. I have not seen many post if any suggesting major problems for this product. I do understand if the problem continues there is another company that would be compatible with what is installed. Starting over even with a total refund would be a major disaster as rewiring would not be possible without redoing all the sheet rock etc. The house has not attic and the runs of wires would be a major issue to start over also. If you google problems with speakercraft or MZC88 my post come up not any others I could see. Again thank you very much for you time and help. PG

 

[TLS Guy]

It is too late to run from but thank you for you thoughts regardless. We use it mostly for whole house sound during entertaining that's about it. I have not seen many post if any suggesting major problems for this product. I do understand if the problem continues there is another company that would be compatible with what is installed. Starting over even with a total refund would be a major disaster as rewiring would not be possible without redoing all the sheet rock etc. The house has not attic and the runs of wires would be a major issue to start over also. If you google problems with speakercraft or MZC88 my post come up not any others I could see. Again thank you very much for you time and help. PG

I think we may be getting to the bottom of it. If you are using this for entertaining, like parties, then I bet you are pushing the level to get above the background.

It is clear from the manual, that this device is only intended to drive two speakers at any thing like a level above background.

If you are trying to raise the level above party noise in multiple rooms, that is your problem.

As stated in the manual, if that is your application you have to add robust external amplification. I think that is going to be true of any unit of that type.

Just consider the facts. This is a small box that contains 16 power amps. Speakercraft can not rewrite the laws of physics. You just can't put 16, 50 watt amps, a power supply and all the microprocessing circuitry in a box that size, throw it in a closet and expect anything other than a Muzak machine.

The installation manual by the way is quite clear on this point.

The other issue is that if that closet is warming up at all, it needs an extractor fan, to keep the closet close to the ambient temperature of the house.

Remember Newton's laws of cooling, the devices heat transfer will decrease to the log of the temperature increase in that closet. Electronics and heat do not mix at all.

In my installation, I have a fan extracting to the outside. In the summer months there are two ducts delivering cold air into the space.

Anyway keep the information coming, I think we are making progress to understanding the reasons for your repetitive failures.

 

[PGG76116]

Thank you again I will keep you informed. PG

 

[PGG76116]

one more thought

I doubt it was heat since this last time l left the door wide open and the AC in that room was set low around 70 there should have been a ton of air flow in there. PG

 

[TLS Guy]

I doubt it was heat since this last time l left the door wide open and the AC in that room was set low around 70 there should have been a ton of air flow in there. PG

Without knowing the exact details and pictures, it is hard to say. I suspect that over driving the unit is the most likely cause of failure.

How many of the 16 amplifier channels of that unit are connected. Of those that are connected how many channels do you drive above background?

I think it likely the final recommendation is going to be external amplification, at least for the amp channels you will be driving above background.