Hey guys,
I just bought a sub (Mirage substrata 1000) for $40.
The guy tells me that the amp is fried. The woofer is still good though.
This is one of those digital 1000 watt plate amps on the back. Stiff 12" cone in a sealed enclosure. Woofer has a massive magnet, huge rubber surround on it and requires tonnes of power.
Now... my tech will go over the plate amp but he tells me not to hold my breath with these digital plate amps.
If the amp is fried (which I'm thinking it will be) what would be my best option to continue using this sub?
I can get another plate amp from say Parts Express but the 1000 watt plate amps are expensive. Can I get away with less power? I was told these types of woofers in sealed cabs require enormous amounts of current.
My other option I guess is to use an amp and an external crossover (which I have)
The amp is a Carver TFM-25 and I have a Paradigm X-30 electronic crossover. I'm just afraid that the amp was not built to drive a sub and I don't want to ruin it.
Any suggestions would be greatly appreciated.
I just bought a sub (Mirage substrata 1000) for $40.
The guy tells me that the amp is fried. The woofer is still good though.
This is one of those digital 1000 watt plate amps on the back. Stiff 12" cone in a sealed enclosure. Woofer has a massive magnet, huge rubber surround on it and requires tonnes of power.
Now... my tech will go over the plate amp but he tells me not to hold my breath with these digital plate amps.
If the amp is fried (which I'm thinking it will be) what would be my best option to continue using this sub?
I can get another plate amp from say Parts Express but the 1000 watt plate amps are expensive. Can I get away with less power? I was told these types of woofers in sealed cabs require enormous amounts of current.
My other option I guess is to use an amp and an external crossover (which I have)
The amp is a Carver TFM-25 and I have a Paradigm X-30 electronic crossover. I'm just afraid that the amp was not built to drive a sub and I don't want to ruin it.
Any suggestions would be greatly appreciated.
sreten said:Hi,
Your main problem is probably any in built EQ, it is almost certain
it uses some form of bass boost, a highish Q boost / subsonic
filter or possibly a Linkwitz transform, its hard to say.
/sreten.
Thanks sreten.
Yes I think you are right. I'm sure that the original digital amp has bass boost built in and a rumble filter as to not rob the amp of all the power.
I checked out Parts Express and they have a plate amp for relatively cheap that has both of these but it is only rated for 250 watts into 4 ohms.
Now when I measured the resistance of the woofer of this Mirage sub, I get a reading of 19 ohms!
I also noticed something else that I didn't understand... Across the pos and neg terminals of the woofer I noticed a cap and a resistor... Values of 47 ohms and 2.2 uf. Why would they have done this?
Before I go buying just any plate amp I want to make sure I'm informed first.
Thanks
Low resistances can be tricky to measure, especially when comparable to the resistance of the test leads, are you certain of that measurement or was it a cheap multimeter job?
If the latter, get a larger resistor, say 100ohm, and measure that with your multimeter, then measure the driver with the 100ohm resistor in series and subtract the resistors measured value from this, you should probably get something less than 19ohms.
Ofcourse you'll need to have that resistor - capacitor (zobel) disconnected from the driver too while measuring.
If the latter, get a larger resistor, say 100ohm, and measure that with your multimeter, then measure the driver with the 100ohm resistor in series and subtract the resistors measured value from this, you should probably get something less than 19ohms.
Ofcourse you'll need to have that resistor - capacitor (zobel) disconnected from the driver too while measuring.
Because the resistance meter does its job by providing a voltage and measuring the current that flows, so when you hook up the ohmmeter aka 'dc voltage supply' it will first see the cap as a short and thus show you the value of the resistor in the zobel, in parallel with the driver Rs, and as the cap charges it's 'resistance' will appear to increase, and after quite a long time it will show the actual drivers resistance, provided the meter is capable of such a low measurement accurately.
Better to just skip the capactor loading sequence.
Better to just skip the capactor loading sequence.
I'll bet that the Mirage amplifier is a direct line switcher. It doesn't have a high voltage transformer to step down the 120VAC. It switches directly from the AC outlet. Since there is such high voltage available this way, the woofer impedance used in these designs is usually very high to limit the power output to a reasonable value.
Tell your tech to be very careful working on this amplifier.
Tell your tech to be very careful working on this amplifier.
Jack Hidley said:
Hi,
That does make sense, but I've never seen a ~ 20 ohm driver.
If it is the case then 47R for the zobel is also very reasonable.
If it is true he is completely stuffed, I've never seen a subamplifier
for ~ 20 ohms either. A very high power amplifier for 8 ohms
bridged is the only option I can think of.
/sreten.Well, I haven't had a chance to take the amp to my tech yet but I did have a chance to hook up this sub to my resident sub set up.
I moved my Titanic MKII 15 out of the way and replaced it with this sub.
I think this sub really is 20 ohms as it took way more power from my Crown Microtech 1200 to drive it. I had to turn the volume waaay up to get even close to the same levels as with the Titanic.
Having said that the woofer in this Mirage is something. No it couldn't keep up with the 15 incher in output but it was very impressive non the less. Very quick yet still went impressively low. And the BFD wasn't even eq'd for that woofer.
So... we'll see what happens when I bring it in. I doubt it can be fixed though. You can see a burn mark on one of the boards and it looks like a chip blew up! NOT GOOD! There is a resistor that has a solder joint that came undone where the speaker leads come in for a high level input. Maybe this caused the amp to blow in the first place??? Who knows.
I think my options will have to be another plate amp or maybe another used pro amp... But one noisy fan is already too much!!!!
I want to use this thing ultimately just for music as I already have a home theater sub. So I might not need another 1000 watt amp. T-Rex won't be playing through this sub... Just some Lyle Lovett and Keb Moe! Maybe I can get away with a 250 watt plate amp replacement with some bass boost built in...
I moved my Titanic MKII 15 out of the way and replaced it with this sub.
I think this sub really is 20 ohms as it took way more power from my Crown Microtech 1200 to drive it. I had to turn the volume waaay up to get even close to the same levels as with the Titanic.
Having said that the woofer in this Mirage is something. No it couldn't keep up with the 15 incher in output but it was very impressive non the less. Very quick yet still went impressively low. And the BFD wasn't even eq'd for that woofer.
So... we'll see what happens when I bring it in. I doubt it can be fixed though. You can see a burn mark on one of the boards and it looks like a chip blew up! NOT GOOD! There is a resistor that has a solder joint that came undone where the speaker leads come in for a high level input. Maybe this caused the amp to blow in the first place??? Who knows.
I think my options will have to be another plate amp or maybe another used pro amp... But one noisy fan is already too much!!!!
I want to use this thing ultimately just for music as I already have a home theater sub. So I might not need another 1000 watt amp. T-Rex won't be playing through this sub... Just some Lyle Lovett and Keb Moe! Maybe I can get away with a 250 watt plate amp replacement with some bass boost built in...
Well, I got the amp back from my tech and... she's toast!
I pretty much new that would be the case though.
So now I'm stuck with a driver and a box... I guess my only option would be to use a very powerful pro amp to drive this woofer?
I measured the woofer again just to make sure and it measured 19 ohms.
Are there any pro (powerful) amps out there that don't have a noisy fan attached to them?
My Crown I'm using for my LFE sub is very noisy.
Thanks for all your input so far gentlemen!
I pretty much new that would be the case though.
So now I'm stuck with a driver and a box... I guess my only option would be to use a very powerful pro amp to drive this woofer?
I measured the woofer again just to make sure and it measured 19 ohms.
Are there any pro (powerful) amps out there that don't have a noisy fan attached to them?
My Crown I'm using for my LFE sub is very noisy.
Thanks for all your input so far gentlemen!
Peavey PV8.5C amps have a two-speed fan that is pretty quiet on low. Bridged, it should still deliver several hundred watts if my calculations are right. It's a 3U high case, so it can run a bigger, slower, quieter fan than 3.5" case amps. I haven't tried the Behringer EP2500 at home; it's a 3.5" case, but it should deliver more power bridged. I've run across both those models used for not much over $200.
If you have a big 120/240 step-down or isolation transformer 500 VA or more, those can be used as audio transformers. A 2:1 voltage ratio should reduce the effective impedance to about 5 ohms (1/4). I've been using that arrangement in reverse with my DIY Contrabass subwoofer for years and nothing has blown up yet.
If you have a big 120/240 step-down or isolation transformer 500 VA or more, those can be used as audio transformers. A 2:1 voltage ratio should reduce the effective impedance to about 5 ohms (1/4). I've been using that arrangement in reverse with my DIY Contrabass subwoofer for years and nothing has blown up yet.
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