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Ask Me Anything About Audio System Design
11-18-2010, 06:19 AM
#181
I have a question...
My Atomic 7K was going into protect for no reason. Even @ cold temps first thing @ startup. If I reset it with my deck it would work fine or cut out a second time, then work for several days before doing it again.
About an hour ago, it popped, and I have one blown FET on each side of the amp. They do not look fried, or melted... rather "popped". Any thoughts on what is causing this? Things to check for?
My Atomic 7K was going into protect for no reason. Even @ cold temps first thing @ startup. If I reset it with my deck it would work fine or cut out a second time, then work for several days before doing it again.
About an hour ago, it popped, and I have one blown FET on each side of the amp. They do not look fried, or melted... rather "popped". Any thoughts on what is causing this? Things to check for?
...
11-18-2010, 07:00 AM
#182
Sure does... 
When I pulled both mine and the twins amps apart there was VERY little dielectric grease on them. I redid mine and it worked flawlessly for 3 days then went into protect again for the last time, as soon as I reset the deck... POP!! Out goes 2 FET's just like the twins did.
So there are 24 field effect transistors in this section of that amp. Maybe I will have to replace them all. I've tested the gate resistors and they all seem to be O.K.
Going to double check the rectifier and toroids today.
When I pulled both mine and the twins amps apart there was VERY little dielectric grease on them. I redid mine and it worked flawlessly for 3 days then went into protect again for the last time, as soon as I reset the deck... POP!! Out goes 2 FET's just like the twins did.
So there are 24 field effect transistors in this section of that amp. Maybe I will have to replace them all. I've tested the gate resistors and they all seem to be O.K.
Going to double check the rectifier and toroids today.
11-18-2010, 11:02 AM
#183
50 Watt CAFz'r
Thread Starter
Join Date: Nov 2010
Posts: 230
Sure does...
When I pulled both mine and the twins amps apart there was VERY little dielectric grease on them. I redid mine and it worked flawlessly for 3 days then went into protect again for the last time, as soon as I reset the deck... POP!! Out goes 2 FET's just like the twins did.
So there are 24 field effect transistors in this section of that amp. Maybe I will have to replace them all. I've tested the gate resistors and they all seem to be O.K.
Going to double check the rectifier and toroids today.
When I pulled both mine and the twins amps apart there was VERY little dielectric grease on them. I redid mine and it worked flawlessly for 3 days then went into protect again for the last time, as soon as I reset the deck... POP!! Out goes 2 FET's just like the twins did.
So there are 24 field effect transistors in this section of that amp. Maybe I will have to replace them all. I've tested the gate resistors and they all seem to be O.K.
Going to double check the rectifier and toroids today.
Cheers
11-18-2010, 04:04 PM
#184
500 Watt CAFz'r
Join Date: May 2007
Posts: 849
As promised!
So you were told that by separating your tweeters from your mids and so-on, that such can lead to some loss in fidelity...
Regardless of where you came across this data, it is in fact true. The fact is, we are striving to create a single driver that can accurately reproduce a bandwidth from 20Hz to 20KHz, and as a point of fact, there are already several that to some extend meet this goal, but they don’t handle much power and they are very box picky and are weak at the top end of the bandwidth...
In the 12-Volt world, we have the coaxial driver which is in fact; two drivers mount one in front of the other, on the same axis – hence the term coaxial. Now in fact, coaxial have many sonic advantages over separates, but haven’t been touted as having such, because for the most part, while the mounting is superior, the drivers used are often not... But for those in the know, if you will, strive to find high-end, high quality coaxial variations of their favourite separates or simply take their favour separates and make a custom mounting system, which arranges the driver in a coaxial fashion – then strive to install them either on or in the dash, in the kick panels or as a last resort – in the stock door locations.
While there are many things occurring hear, all of them are related to phase and the resulting constructive or destructive interference patterns that occur. When a multiple of drivers are utilised to radiate a bandwidth, inherent phase errors occur, which are commonly referred to as Lobing. When a single driver, a coincidental driver or a coaxial is implemented, Lobing mitigated.
Understanding Lobing
Lobing occurs when sound waves are radiated from two or more driver locations, creating an irregular off-axis frequency response.
Picture yourself sitting an equal distance between two individual drivers, now as identical tones begin coming from each, they will all arrive at your ears at the same time, adding together, summing their outputs, creating a prescribed frequency response, increasing the overall volume, while simultaneously creating an ambient sound field, which in true high fidelity system, would possess a transparent 3-dimensional sound field, producing a strong image of instrument placement etc...
Now picture that you have moved one speaker back a distance equal to twice that of its previous distance, from where you are sitting. This time, as the tones reach your ears, they are out of phase; where some tones are at the peak of their phase (90-degrees – 250ms), the others are at their trough (180-degrees-500ms), so they cancel completely and you hear nothing. Now this is an extreme occurrence, but what normally occurs, is a degrees of summing and a degree of cancellation...
Along with these effects, as each driver becomes further and further apart, they become more beamy and easy to localize and discern as a separate sound sources – less or no unity in radiation – not a desirable occurrence in higher quality systems...
In this way, frequency response and sonic stereo fidelity is altered, negatively.
So what can be done about it?
1. Use less drivers – positioning them as vertical as possible
2. Place drivers as close together as possible & as on axis with the listener as possible
3. Use coaxial or other similar drivers
4. Extensively rework a passive cross-over – very tuff and expensive to get right
5. Incorporate a completely active, multi-channel DSP & Amplification network – with manual time alignment features and tweak it up!
In your case, if your mids are in the door and you drop your tweeter to meet them, your sound stage will drop as well, because 75% of your bandwidth is radiating out of your tweeters... move your tweeters -move your sound stage; however, if you’re able to modify the doors and angle both the tweeter and mid-range upward, you will probably enjoy the new sound over your old...
Perhaps you could use a little 3M (yellow) double sided tape and temporarily move/ adhere your tweeters at various locations on the door to: a) determine the best location and b) to determine if you’re likely to like the new sound...
As a tip get creative - I put mine under my seat aiming upward and in this way, they are closer to my mids, the radiation pattern is aimed up and the location is difficult to discern because the tweeter are down low and back, but their radiation sounds as if it's coming off the glass.
So you were told that by separating your tweeters from your mids and so-on, that such can lead to some loss in fidelity...
Regardless of where you came across this data, it is in fact true. The fact is, we are striving to create a single driver that can accurately reproduce a bandwidth from 20Hz to 20KHz, and as a point of fact, there are already several that to some extend meet this goal, but they don’t handle much power and they are very box picky and are weak at the top end of the bandwidth...
In the 12-Volt world, we have the coaxial driver which is in fact; two drivers mount one in front of the other, on the same axis – hence the term coaxial. Now in fact, coaxial have many sonic advantages over separates, but haven’t been touted as having such, because for the most part, while the mounting is superior, the drivers used are often not... But for those in the know, if you will, strive to find high-end, high quality coaxial variations of their favourite separates or simply take their favour separates and make a custom mounting system, which arranges the driver in a coaxial fashion – then strive to install them either on or in the dash, in the kick panels or as a last resort – in the stock door locations.
While there are many things occurring hear, all of them are related to phase and the resulting constructive or destructive interference patterns that occur. When a multiple of drivers are utilised to radiate a bandwidth, inherent phase errors occur, which are commonly referred to as Lobing. When a single driver, a coincidental driver or a coaxial is implemented, Lobing mitigated.
Understanding Lobing
Lobing occurs when sound waves are radiated from two or more driver locations, creating an irregular off-axis frequency response.
Picture yourself sitting an equal distance between two individual drivers, now as identical tones begin coming from each, they will all arrive at your ears at the same time, adding together, summing their outputs, creating a prescribed frequency response, increasing the overall volume, while simultaneously creating an ambient sound field, which in true high fidelity system, would possess a transparent 3-dimensional sound field, producing a strong image of instrument placement etc...
Now picture that you have moved one speaker back a distance equal to twice that of its previous distance, from where you are sitting. This time, as the tones reach your ears, they are out of phase; where some tones are at the peak of their phase (90-degrees – 250ms), the others are at their trough (180-degrees-500ms), so they cancel completely and you hear nothing. Now this is an extreme occurrence, but what normally occurs, is a degrees of summing and a degree of cancellation...
Along with these effects, as each driver becomes further and further apart, they become more beamy and easy to localize and discern as a separate sound sources – less or no unity in radiation – not a desirable occurrence in higher quality systems...
In this way, frequency response and sonic stereo fidelity is altered, negatively.
So what can be done about it?
1. Use less drivers – positioning them as vertical as possible
2. Place drivers as close together as possible & as on axis with the listener as possible
3. Use coaxial or other similar drivers
4. Extensively rework a passive cross-over – very tuff and expensive to get right
5. Incorporate a completely active, multi-channel DSP & Amplification network – with manual time alignment features and tweak it up!
In your case, if your mids are in the door and you drop your tweeter to meet them, your sound stage will drop as well, because 75% of your bandwidth is radiating out of your tweeters... move your tweeters -move your sound stage; however, if you’re able to modify the doors and angle both the tweeter and mid-range upward, you will probably enjoy the new sound over your old...
Perhaps you could use a little 3M (yellow) double sided tape and temporarily move/ adhere your tweeters at various locations on the door to: a) determine the best location and b) to determine if you’re likely to like the new sound...
As a tip get creative - I put mine under my seat aiming upward and in this way, they are closer to my mids, the radiation pattern is aimed up and the location is difficult to discern because the tweeter are down low and back, but their radiation sounds as if it's coming off the glass.
I will try to find a better location for my tweeters so that they are closer to mids, I should be able to axis them a little towards my ears also.
And you are correct about the tweeters being 75% of the soundstage, The sound is much louder with the tweeters up high.
The Speakers I have are Morel Tempo's and I really want to get the best out of them.
Thanks for your help!
11-18-2010, 05:45 PM
#185
50 Watt CAFz'r
Thread Starter
Join Date: Nov 2010
Posts: 230
Thanks so much for this detailed answer, I've always wanted an answer on something like this.
I will try to find a better location for my tweeters so that they are closer to mids, I should be able to axis them a little towards my ears also.
And you are correct about the tweeters being 75% of the soundstage, The sound is much louder with the tweeters up high.
The Speakers I have are Morel Tempo's and I really want to get the best out of them.
Thanks for your help!
I will try to find a better location for my tweeters so that they are closer to mids, I should be able to axis them a little towards my ears also.
And you are correct about the tweeters being 75% of the soundstage, The sound is much louder with the tweeters up high.
The Speakers I have are Morel Tempo's and I really want to get the best out of them.
Thanks for your help!
11-19-2010, 02:52 AM
#186
50 Watt CAFz'r
Join Date: Mar 2006
Posts: 50
Interesting thread. I'm not sure if I know Dogbaker. I've been at this for FAR too long,
so it's good to read stuff from someone else who's been in the industry long enough to remember when 4-track machines were replaced by those new-fangled 8-track units.
Welcome, DB.
FWIW, my admittedly limited understanding of the demise of Mobile Dynamics didn't have
anything to do with their instruction or cirriculum. More of an oversight problem.
Feel free to PM me if you're interested in doing some tech/training related business in China. Been here (Hong Kong) long enough to see that the PRC could benefit from a well-run, technically proficient training program. The car culture in China is phenomenal,
and shops doing car audio builds are good at making things look good, but they clearly don't understand how to make them sound decent.
so it's good to read stuff from someone else who's been in the industry long enough to remember when 4-track machines were replaced by those new-fangled 8-track units.
Welcome, DB.
FWIW, my admittedly limited understanding of the demise of Mobile Dynamics didn't have
anything to do with their instruction or cirriculum. More of an oversight problem.
Feel free to PM me if you're interested in doing some tech/training related business in China. Been here (Hong Kong) long enough to see that the PRC could benefit from a well-run, technically proficient training program. The car culture in China is phenomenal,
and shops doing car audio builds are good at making things look good, but they clearly don't understand how to make them sound decent.
11-19-2010, 11:50 AM
#189
50 Watt CAFz'r
Thread Starter
Join Date: Nov 2010
Posts: 230
Interesting thread. I'm not sure if I know Dogbaker. I've been at this for FAR too long,
so it's good to read stuff from someone else who's been in the industry long enough to remember when 4-track machines were replaced by those new-fangled 8-track units.
Welcome, DB.
FWIW, my admittedly limited understanding of the demise of Mobile Dynamics didn't have
anything to do with their instruction or cirriculum. More of an oversight problem.
Feel free to PM me if you're interested in doing some tech/training related business in China. Been here (Hong Kong) long enough to see that the PRC could benefit from a well-run, technically proficient training program. The car culture in China is phenomenal,
and shops doing car audio builds are good at making things look good, but they clearly don't understand how to make them sound decent.
so it's good to read stuff from someone else who's been in the industry long enough to remember when 4-track machines were replaced by those new-fangled 8-track units.
Welcome, DB.
FWIW, my admittedly limited understanding of the demise of Mobile Dynamics didn't have
anything to do with their instruction or cirriculum. More of an oversight problem.
Feel free to PM me if you're interested in doing some tech/training related business in China. Been here (Hong Kong) long enough to see that the PRC could benefit from a well-run, technically proficient training program. The car culture in China is phenomenal,
and shops doing car audio builds are good at making things look good, but they clearly don't understand how to make them sound decent.
11-19-2010, 12:02 PM
#190
from time to time this happens. that's like white people who are good at inventing physically enduring team sports but suck when it comes to playing them.
