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Discussion Starter · #1 ·
I have an Energy Microstar 12.1 subwoofer and the amplifier module blew. The pc board has "API DGAMP" (product of Audio Products Int'l) and "REV 4b" markings on it. A quick call to Energy support to hopefully buy a replacement but was told product is too old and no longer in stock. Buy a new sub he says. It just seems such a waste to trash a working subwoofer with a beautiful piano black enclosure. Not to mention $1500 retail back in its days.


After some searching, I'm leaning towards buying the Parts Express " Dayton HPSA500 500W Subwoofer Amplifier " for $250. The cut dimensions are slightly bigger at 10"x10" vs. 9"x9" so I'll need to mod it a bit.


I've never built a custom sub or have any experience with these amps. Is this amp overkill? Go get a BASH amp? Wrong amp for my sealed box? Any input appreciated. Thanks!
 

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Quote:
Originally Posted by todd612 /forum/post/16915194


I have an Energy Microstar 12.1 subwoofer and the amplifier module blew. The pc board has "API DGAMP" (product of Audio Products Int'l) and "REV 4b" markings on it. A quick call to Energy support to hopefully buy a replacement but was told product is too old and no longer in stock. Buy a new sub he says. It just seems such a waste to trash a working subwoofer with a beautiful piano black enclosure. Not to mention $1500 retail back in its days.


After some searching, I'm leaning towards buying the Parts Express " Dayton HPSA500 500W Subwoofer Amplifier " for $250. The cut dimensions are slightly bigger at 10"x10" vs. 9"x9" so I'll need to mod it a bit.


I've never built a custom sub or have any experience with these amps. Is this amp overkill? Go get a BASH amp? Wrong amp for my sealed box? Any input appreciated. Thanks!
http://www.oaudio.com/500W_SUBAMP.html


If you're looking for a 500w amp, it's output has been tested and it's definitely a good value at this price. Mine is actually due to arrive today or tomorrow.


Edit: aside from that, I'm sort of new to DIY, so you'll have to ask someone else your questions, but it's well known that the Oaudio amp is a pretty good buy around here.
 

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My guess is that the microstar used an amp with well over 1,000 watts and some significant eq to get solid output from a small box (and it could get loud from my memory - I owned one years ago). If you are going to attempt a new plate amp I would consider the Keiga KGND52100.


JP
 

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I'm sorry to have to tell you that it is not as simple as buying a new plate amp, unless you buy an exact replacement.

The reason for the difficulty, is this is a servo-sub.


You might be better off getting your existing 1500 Watt RMS, Pulse Width Modulation amplifier repaired, if you cannot locate an exact replacement amp.


What are the fail symptoms? I'm just curious.
 

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Discussion Starter · #5 ·
PassingInterest,


That's bad news. You read my mind though. I was set to just buy a new plate amp and drop it in. I have no idea what a servo-sub is, but thanks for point this out.


I doubt I can find an exact replacement. I called Energy techsupport and they do not have this amp part anymore. Also, I took it to a local electronics repair shop and they're want ~$200 to repair it. Outrageous.


The symptoms were:

It stopped working one day last week. Power LED comes on. When I switch "Off/Auto/On" I can hear it switching on. There is no sound coming from subwoofer unless I turn gain to maximum. Then I hear a barely audible sputtering sound.


Since I knew my warranty expired years ago. I unscrewed the plate amp to have it examined. No burnt fuse and all electronic component visibly looks perfect. Curious, I disconnected the speaker and power LED leads to amp. But when I plugged in the power plug (with no leads connected to amp) I blew a capacitor.


The subwoofer still works. With the box open, I connected my speaker out direct from amp to sub and I hear sound.


Any suggestions to get this repaired? I'm in San Francisco.
 

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Wiki has an explanation of a servo sub here .

You have to scroll down to the servo sub part.

Great information on subwoofers overall there.


Basically, a servo sub uses some means of monitoring cone movement.

Cone movement information is sent back to the amp driving the cone, and adjustments are made by the amp to correct for errors in cone movement.


You can also try Ebay for a replacement amp, if you haven't already.


Or, you may be able to effect repairs yourself--if you are comfortable with a soldering iron. Otherwise, you might get a friend to help out.


You know you have a blown capacitor. If you can determine its value, replace it with a new one.

If it is an electrolytic capacitor, it may be poloraized, meaning it must be installed with the same orientation as the original (+) and (-).

A poloaized electrolytic will have an arrow with either a (-) (most often seen) to identify the negative lead, or a (+) (less often seen) to identify the positive lead.

If you install a polarized capacitor backward, you will geatly shorten its life, often to a few seconds. Often with a bang and a mess to clean up.

Not to scare you, just make sure you watch the polarization on electrolytics.

A non-polarized electrolytic will have no arrow to identify the leads.


It is just possible that the capacitor was getting ready to go, and that that was the problem all along. If so, this would be a cheap fix.


Of course, any soldering must be done with the amp unplugged from any power source and any signal source.


If repairs are just not feasible, and no exact replacement amp can be located, it is possible to still use the original driver in the original box, but it would require an outboard amp and something like a Behringer Feedback Destroyer and a calibrated microphone and experimentation with equilization.

This is necessary, because the small box requires a great deal of equilization in order to obtain good sounding performance. This approach would require sealing the plate amp opening, of course. The dead plate amp is fine for this.


Another option, is to reuse the driver in a larger box, but you need the Theile-Small parameters, before you can design a box for that driver.


I hope this helps.


You made some good, detailed observations. That is helpful.

Let us know how it goes.


Pi
 

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Discussion Starter · #7 ·
Pi,


From what you described, it's a polarized electrolytic capacitor. How do I find out what value the cap is since the top blew and I don't have the schematics? If it's just the cap that would be awesome as I have no problem using a soldering iron.


In the event I can't repair this myself, Energy techsupport given me one more option. They have an "approved" repair shop in Michigan but the repair cost is a flat $240. That's a little steep. For a $100 I'll do it and anything over I feel like like buying a new sub.


Alternatively, what about these Rhythik subwoofer amplifiers ? Would these work instead of the Behringer you've mentioned?


See picture of the blown cap below or click here for the entire album .

 

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Sorry, my bad.

That's a tantalum capacitor, and it is polarized as well.


Without a schematic, I know of no good way to determine the value of the blown capacitor, unless perhaps if you can talk another owner into looking inside of his or her plate amp.


It is not common for tantalums to just go bad, like electrolytics often do, unless there is a design issue, or that part of the circuit was frequently driven hard or a heat buildup issue. So, it is likely that there is more wrong with your amp than just that one capacitor.


Another amplifier, such as one from the group you mentioned, would provide an amplified signal to your driver, but it wouldn't sound very musical without a great deal of equilazation.


Eddie had a good, practical suggestion for you. It can't hurt to ask about a price for repairs.


I don't consider $240 a reasonable price, either.

Profitable, yes. Reasonable, no.


Pi
 

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Discussion Starter · #10 ·

Quote:
Originally Posted by PassingInterest /forum/post/16918587


I'm sorry to have to tell you that it is not as simple as buying a new plate amp, unless you buy an exact replacement.

The reason for the difficulty, is this is a servo-sub.


You might be better off getting your existing 1500 Watt RMS, Pulse Width Modulation amplifier repaired, if you cannot locate an exact replacement amp.


What are the fail symptoms? I'm just curious.

Well, I've exhausted all my resources in getting this exact amp repaired or replaced. Seems like my only option now is to get a replacement amp plate if I'm still adamant in resurrecting this sub.


The question I have now is: are you sure this is a servo-sub? It only has two leads (red positive and black negative) connected directly to the driver. From my understanding, a servo-sub should have four leads (two to driver and two for feedback input). Hopefully, someone can confirm this so I can proceed and order a replacement plate amp.
 

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It's difficult to find much information on the Energy Microstar 12.1 subwoofer.

But, considering the size of the enclosure, it seems likely that it is a servo sub.

I read something about it before I posted earlier in this thread, but I can't seem to find it again.

The 1500 watt amp spec. is almost certainly peak power. I doubt that the RMS power rating would reach 500 watts.

If this is not a servo sub, then a considerable amount of equilization is used to smooth out performance of the driver in that small enclosure.

While I haven't found a good source of information on this sub, I have seen that it is normally compared to other legacy servo subs, such as Bob Carver's Sunfire and Velodyne.

The Energy website shows no information that I could find on this sub. Apparently, they're not very interested in supporting their legacy products, as you learned when you contacted them regarding repairs.


CZEddie had some good advice earlier in this thread. If you haven't already contacted the guy he recommended for repairs, you should at least give him a shout.


Other than that, you might try an external amplifier, just to see how it sounds--if you have one, or can borrow one.

You'd have to make some modifications of course--but that goes without saying--because, you have to wire directly to the driver.

It should be easy to replace the plate amp with a board, which has a banana jack pair mounted on it (you have to make an air-tight seal).


It might seem like a lot of bother for nothing, but I'd hate for you to shell out some bucks for a plate amp, only to find the sound unpalatable.

Plus, an external amp--even a borrowed one--should allow you to experiment a bit with equalization, so you know what kind of eq to look for in a plate amp, or at least how much bass boost you need. And, you will certainly need some bass boost due to the cabinet size.

Just a thought.

Hope it helps.
 

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Discussion Starter · #13 ·
Tried the test today and it didn't sound too good. Turning up the gain (or volume on amp) caused the driver to crack. Woofer would throw like crazy with no low boom. So I reversed the connections back to the MFW-15 driver and it was smooth. Does this mean the Energy driver can't handle the power?


But it wasn't like that when it was working. I was using it in a 20'X25' studio and it would rattle the windows. You can feel and hear quality boom boom sound. The sound is not as "big" as the MFW-15 but nothing to sneer at.


Well, I need to do more test...
 

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Quote:
Originally Posted by todd612 /forum/post/17124033


Tried the test today and it didn't sound too good. Turning up the gain (or volume on amp) caused the driver to crack. Woofer would throw like crazy with no low boom. So I reversed the connections back to the MFW-15 driver and it was smooth. Does this mean the Energy driver can't handle the power?


But it wasn't like that when it was working. I was using it in a 20'X25' studio and it would rattle the windows. You can feel and hear quality boom boom sound. The sound is not as "big" as the MFW-15 but nothing to sneer at.


Well, I need to do more test...

Can you run REW (Room Equalization Wizard)?

It would be helpful if you could get some graphs of your sub's performance.

I think you will be able to see in a graph that your Energy Microstar needs a considerable amount of equalization to smooth out its response--both in room and outdoors.

Remember, we anticipated poor performance from that driver in that small enclosure without any servo-feedback loop within the amplifier, or a considerable amount of equalization.


But, I think I did not quite answer your question.

As for the "cracking" sound of your driver with the MFW-15's 350 Watt plate amp--you are clearly overdriving the subwoofer.


As for the question concerning whether it can handle the power--it might not be a pure "power" issue. Rather, it might be a "frequency" issue.

I'm getting theroetical here, because I don't know the specifics of the driver or the MFW's amp.

But, just suppose the driver has a natural performance peak or even a resonance at a certain frequency, or that the box/driver combination has a resonance at a certain frequency--it wouldn't take much to overdrive the sub at that frequency.


To make matters worse, the MFW plate amp may have some bass boost at that frequency, which would exacerbate the problem considerably.


I'm no expert, so you have to take anything I say with a grain of salt--perhaps several pounds of pure rock salt.


Still, I think it is clear that you proved that your Microstar is in fact a servo sub, or its amp incorporates a great deal of equalization.

Which means that you either need a suitably matched servo-amp for that driver in that enclosure, or you need a considerable amount of equalization.
 

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Quote:
Originally Posted by Thatsnasty /forum/post/16915783

http://www.oaudio.com/500W_SUBAMP.html


If you're looking for a 500w amp, it's output has been tested and it's definitely a good value at this price. Mine is actually due to arrive today or tomorrow.


Edit: aside from that, I'm sort of new to DIY, so you'll have to ask someone else your questions, but it's well known that the Oaudio amp is a pretty good buy around here.

+1.


bang for the buck including features, o-audio is pretty strong.
 

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howdy, i too have a microstar 12.1, mine works. am interested in aquiring old plate amps from your unit, if you still have.need to rebuild for a spare. and also, amp actually does between 1000 and 1350 watts on peaks, but difficult to utilize all db's. please reply asap. Thanks
 
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