Ok everyone this will be a thread for all you DIY guys that are die hard audio fans and repair junkies like myself.
Lets get some opinions and some facts. What are some of the best most solidly built reliable amps you have owned and or repaired and why.
Lets also list the worst, being the most poorly designed and built and difficult to repair and find parts.
Lets also post some amp guts pics as well.
I think this thread could get very interesting, but lets keep in mind some people have opinions and will disagree about what is the best. If your going to state your opinion know your facts to back it up.
Lets try and be professional and not argue or get pissed at each other about what amp is the best with out stating your facts to back it up.
Lets begin............................
Lets get some opinions and some facts. What are some of the best most solidly built reliable amps you have owned and or repaired and why.
Lets also list the worst, being the most poorly designed and built and difficult to repair and find parts.
Lets also post some amp guts pics as well.
I think this thread could get very interesting, but lets keep in mind some people have opinions and will disagree about what is the best. If your going to state your opinion know your facts to back it up.
Lets try and be professional and not argue or get pissed at each other about what amp is the best with out stating your facts to back it up.
Lets begin............................
Amps can have different types of problems. Some are electrical/electronic. Others are physical/mechanical.
The best (overall)
I always recommend Rockford so I'll start with those. They have had VERY few mechanical problems where the amps would self destruct when subjected to vibration. This may not seem like a problem but many amps cannot handle vibration without being damaged. Some exceptions were the HD and similar amps that had the transistors mounted perpendicular to the board. The caps in some of the Rockford amps (particularly the 10uF@16v SMD electrolytic caps) were a problem and cause amps to fail. This was more bad luck than a poor design. Rockford didn't manufacture the caps and could not have predicted that they would leak. I also like the fact that Rockford will provide technical literature for most of their amps. Most manufacturers will not even reply when you inquire about schematic diagrams. The biggest problem with older Rockford amps is that they didn't have any DC offset protection which could lead to the destruction of speakers if the output transistors failed.
The worst (or should I say the best.. for someone in the repair business)
The clone amps used by many different manufacturers (attached image). If you have one of these amps, you can expect the amp to have problems at each of the points indicated in the attached image. These amps have been around for probably 10 years and they still haven't resolved all of the issues. They keep trying but many of the solutions are inadequate, often due to (what seems to be) a desire to make them as cheap as possible. Most of the failures are due to mechanical problems but some are due to poor selection of the components on the driver board. One manufacturer has started using better parts but that's the exception.
The best (overall)
I always recommend Rockford so I'll start with those. They have had VERY few mechanical problems where the amps would self destruct when subjected to vibration. This may not seem like a problem but many amps cannot handle vibration without being damaged. Some exceptions were the HD and similar amps that had the transistors mounted perpendicular to the board. The caps in some of the Rockford amps (particularly the 10uF@16v SMD electrolytic caps) were a problem and cause amps to fail. This was more bad luck than a poor design. Rockford didn't manufacture the caps and could not have predicted that they would leak. I also like the fact that Rockford will provide technical literature for most of their amps. Most manufacturers will not even reply when you inquire about schematic diagrams. The biggest problem with older Rockford amps is that they didn't have any DC offset protection which could lead to the destruction of speakers if the output transistors failed.
The worst (or should I say the best.. for someone in the repair business)
The clone amps used by many different manufacturers (attached image). If you have one of these amps, you can expect the amp to have problems at each of the points indicated in the attached image. These amps have been around for probably 10 years and they still haven't resolved all of the issues. They keep trying but many of the solutions are inadequate, often due to (what seems to be) a desire to make them as cheap as possible. Most of the failures are due to mechanical problems but some are due to poor selection of the components on the driver board. One manufacturer has started using better parts but that's the exception.
Attachments
I agree with Perry on the Rockford amps. I am starting to branch out in my repairs but I mainly specialize in Rockford and stock thousands of parts for them. Rockford Fosgate has been in the game for along time and in my opinion were always ahead of the rest in technology.
Lets take the Punch DSM amps for example. They utilized many key features that others did not for that era in amp production. They used independent gain controls for each channel allowing precise level matching. They had the punch equalization circuits allowing 18db of bass boost at 45Hz, and 12 db of treble boost at 20kHz which really helped with vehicle interior interference.
Lets not forget the NOMAD (non-multiplying advanced decision) a protection circuit that used an analog computer to make decisoins regarding temperature, voltage, current and impedence. Did a good job of protecting the amp itself but not your speakers.
Lets not forget TOPAZ (tracking operational pre-amp zone) a circuit that eliminated ground loop noise by referencing signal ground from the first component in the chain.
Another advantage the mosfet circuitry in the power supply and output stage, producing high speed, thermal stability, high current capability, and very smooth accurate sound quality.
My favorite of all was the XCARD an option that could be configured for full range, high pass, low pass, and was infinitely adjustable.
More great features such as INDIGO (indexed ideal gain operation) which allowed the power supply to operate at different indexed regulation gains or power levels as needed. It optimized its performance by making better use of the power that is in the car. It tightly regulated front end (low level) components and at the same time allows output components to swing with battery voltage. That allowed the amp to deliver more power, clean sound, and tight bass.
They also utilized TRANS ana (transconductance active nodal amplifier) a circuit that simplifies the input path allowing the signal to travel through the amplifier at low voltage achieving current and voltage gain in a single stage.
Another great feature was the DSM technology they used eliminating most all the "OLD" through hole technology resulting in greater efficiency, less noise, and higher output.
The vibration theory Perry had described I agree with. I have had and do have many Rockford amps. I think it was due to their extruded aluminum heat sink and its ability to absorb vibration and had much greater cooling capabilities than the "OLD" conventional extruded sinks.
I think this is enough rambling for one post maybe I will discuss the Power series and 4 channel DSM amps in my next post. Then maybe we can also talk power cube ratings vs various amp manufacturers.
A very fine example would be this 200X2 I have posted a few pics of. The power cube test revealed that this amp performed almost a perfect cube.
8 ohm stereo 60 degrees 85W per channel
4 ohm stereo 60 degress 157w per channel
2 ohm stereo 60 degrees 254w per channel
1 ohm stereo 60 degrees 373w per channel
8 ohms bridged 60 degrees 320w
4 ohms bridged 60 degrees 528w
2 ohms bridged 60 degrees 760w
1 ohms bridged 60 degrees 673w
These tests were done at 14.4 volts not bad!! Its only a 200 watt amp right???
Lets take the Punch DSM amps for example. They utilized many key features that others did not for that era in amp production. They used independent gain controls for each channel allowing precise level matching. They had the punch equalization circuits allowing 18db of bass boost at 45Hz, and 12 db of treble boost at 20kHz which really helped with vehicle interior interference.
Lets not forget the NOMAD (non-multiplying advanced decision) a protection circuit that used an analog computer to make decisoins regarding temperature, voltage, current and impedence. Did a good job of protecting the amp itself but not your speakers.
Lets not forget TOPAZ (tracking operational pre-amp zone) a circuit that eliminated ground loop noise by referencing signal ground from the first component in the chain.
Another advantage the mosfet circuitry in the power supply and output stage, producing high speed, thermal stability, high current capability, and very smooth accurate sound quality.
My favorite of all was the XCARD an option that could be configured for full range, high pass, low pass, and was infinitely adjustable.
More great features such as INDIGO (indexed ideal gain operation) which allowed the power supply to operate at different indexed regulation gains or power levels as needed. It optimized its performance by making better use of the power that is in the car. It tightly regulated front end (low level) components and at the same time allows output components to swing with battery voltage. That allowed the amp to deliver more power, clean sound, and tight bass.
They also utilized TRANS ana (transconductance active nodal amplifier) a circuit that simplifies the input path allowing the signal to travel through the amplifier at low voltage achieving current and voltage gain in a single stage.
Another great feature was the DSM technology they used eliminating most all the "OLD" through hole technology resulting in greater efficiency, less noise, and higher output.
The vibration theory Perry had described I agree with. I have had and do have many Rockford amps. I think it was due to their extruded aluminum heat sink and its ability to absorb vibration and had much greater cooling capabilities than the "OLD" conventional extruded sinks.
I think this is enough rambling for one post maybe I will discuss the Power series and 4 channel DSM amps in my next post. Then maybe we can also talk power cube ratings vs various amp manufacturers.
A very fine example would be this 200X2 I have posted a few pics of. The power cube test revealed that this amp performed almost a perfect cube.
8 ohm stereo 60 degrees 85W per channel
4 ohm stereo 60 degress 157w per channel
2 ohm stereo 60 degrees 254w per channel
1 ohm stereo 60 degrees 373w per channel
8 ohms bridged 60 degrees 320w
4 ohms bridged 60 degrees 528w
2 ohms bridged 60 degrees 760w
1 ohms bridged 60 degrees 673w
These tests were done at 14.4 volts not bad!! Its only a 200 watt amp right???
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Reason why I asked Perry about what is his favorite series of car amps, because I used to work for PPI and MTX amp factories here in south Phoenix AZ in late 90s and I was able to get palet load of bad PPI 'sedona series' and MTX 'thunder 500D' series amps, that I had fun time fixing.
I can tell you that these late 90s PPI amps had a huge design flaw, lower lid of the amp was also a pressure device for the transistors to the heat sink that was held only by two small screews that got lose do to vibration of the bass. And the transistors would just burn up.
The MTX thunder series late 90s with black housing and chrome brand label have parasitic load onto car's battery do to the poor outdated design of the 'remote on', heat sink housing is very small and compact with no fins to cool the amp, so these amps would blow two resistors and few gates just from normal use.
I sold all of those and was hesitant to buy another brand of AMP for my car, I just want something that has all the issues resolved, like:
1: adequate heat sink/housing design to cool power transistors
2: no parasitic load onto car's battery when car is off
3: overrated quality internal parts that can handle abuse
4: great protection where the amp shuts down instead of burning up
5: great input output connections, not some cheap plastics
6: nice clean sound output without ignition coil noise, no pop noise when turned on
I can tell you that these late 90s PPI amps had a huge design flaw, lower lid of the amp was also a pressure device for the transistors to the heat sink that was held only by two small screews that got lose do to vibration of the bass. And the transistors would just burn up.
The MTX thunder series late 90s with black housing and chrome brand label have parasitic load onto car's battery do to the poor outdated design of the 'remote on', heat sink housing is very small and compact with no fins to cool the amp, so these amps would blow two resistors and few gates just from normal use.
I sold all of those and was hesitant to buy another brand of AMP for my car, I just want something that has all the issues resolved, like:
1: adequate heat sink/housing design to cool power transistors
2: no parasitic load onto car's battery when car is off
3: overrated quality internal parts that can handle abuse
4: great protection where the amp shuts down instead of burning up
5: great input output connections, not some cheap plastics
6: nice clean sound output without ignition coil noise, no pop noise when turned on
Mtx had alot of problems with ground noise also remember their rubber footies if you will to isolate the rca shield, I dont know how well that worked.
PPI i was surprised never left the prehistoric through hole design components. I have not worked on alot of them but I believe their boards were one sided with lots of jumper wires and sky wires. They always ran hot and failed constantly.
The orion amps I had a few back in the day and had nothing but problems with them over heating and burning up.
Dont forget the cheaply made Jensen with phenolic boards, jumper wires, sky wires, korean fets, and always had leaking caps.
I love the old rockford amps but if your looking for an amp that meets all the criteria you listed I would consider a new gen rockford power series. They are very small, very efficient, dont over heat, very clean power, and have gobs of power and head room.
PPI i was surprised never left the prehistoric through hole design components. I have not worked on alot of them but I believe their boards were one sided with lots of jumper wires and sky wires. They always ran hot and failed constantly.
The orion amps I had a few back in the day and had nothing but problems with them over heating and burning up.
Dont forget the cheaply made Jensen with phenolic boards, jumper wires, sky wires, korean fets, and always had leaking caps.
I love the old rockford amps but if your looking for an amp that meets all the criteria you listed I would consider a new gen rockford power series. They are very small, very efficient, dont over heat, very clean power, and have gobs of power and head room.
While I don't like the fact that PPI used the bottom cover as a clamp, I've never seen one that vibrated loose. I have seen lots of them with stripped screw holes but that was due to over-tightening or repeated removal/reinstallation of the screws.
The 500D's main problem was the voltage regulators. They operated at extremely high temperatures and failed. When they failed, they made a mess of the amp.
I don't have a problem with through-hole parts. At the frequencies used in audio amplifiers, there's no significant advantage for SMD parts.
The cheap plastic RCA jacks are some of the best in terms of making a reliable connection. The ones on the amp that Sean posted almost never failed. The ones used by Orion and PPI (all metal frame) are some of the worst. They almost always have a weak connection on the center conductor. Many times the RCA shield would break away from the frame and cause intermittent problems.
The parasitic load presented by the MTX amps was insignificant and unless you only drove your vehicle once a month, it wasn't likely to cause a problem.
Many class D amps need no fins because they dissipate very little power. Some amps have the fins on the inside and an internal fan to force air over them.
The 500D's main problem was the voltage regulators. They operated at extremely high temperatures and failed. When they failed, they made a mess of the amp.
I don't have a problem with through-hole parts. At the frequencies used in audio amplifiers, there's no significant advantage for SMD parts.
The cheap plastic RCA jacks are some of the best in terms of making a reliable connection. The ones on the amp that Sean posted almost never failed. The ones used by Orion and PPI (all metal frame) are some of the worst. They almost always have a weak connection on the center conductor. Many times the RCA shield would break away from the frame and cause intermittent problems.
The parasitic load presented by the MTX amps was insignificant and unless you only drove your vehicle once a month, it wasn't likely to cause a problem.
Many class D amps need no fins because they dissipate very little power. Some amps have the fins on the inside and an internal fan to force air over them.
The only advantage to smd parts in my opinion is larger board traces and double sided boards which eliminates all the jumpers and sky wires. I think it gains you efficiency, LESS noise, and higher output. The repairs are much easier on smd components especially when testing due to the fact you dont have to remove the board 5 times to repair them during testing.
I don't work on car electronics. I work in broadcast video and I can tell you that SMD electrolytic capacitors are the most failure prone parts in the machines. I'm talking $80,000 tape machines so cost of the caps really isn't a big deal. I've changed literally thousands over the last several years. I don't buy the same parts Sony originally installed as they failed once, why use them again? Panasonic FK series are better than original most times.
The main issue with them is heat either external and/or internal heating due to ESR. When you buy caps you want highest ripple current possible as that will have minimal self heating. It's as important as the temperature rating because at least indoors it never reaches 85ºC much less 105ºC.
G²
The main issue with them is heat either external and/or internal heating due to ESR. When you buy caps you want highest ripple current possible as that will have minimal self heating. It's as important as the temperature rating because at least indoors it never reaches 85ºC much less 105ºC.
G²
SMD components are not going to make the amp more efficient (more power out with no increased power in). That's largely determined by the type of circuit used.
Noise is also a function of the circuit design and layout. A competent design engineer can layout a perfectly quiet amp with through-hole parts.
It's also possible to layout large multi-channel amps without point to point wiring. The large PPI amps are one example. They use large bussbars but those are necessary on SMD amps also.
I don't generally reinstall the board until I've finished troubleshooting. The exception would be where components run hot normally (linear voltage regulators, for example) and must be clamped to the heatsink to prevent them from overheating.
Noise is also a function of the circuit design and layout. A competent design engineer can layout a perfectly quiet amp with through-hole parts.
It's also possible to layout large multi-channel amps without point to point wiring. The large PPI amps are one example. They use large bussbars but those are necessary on SMD amps also.
I don't generally reinstall the board until I've finished troubleshooting. The exception would be where components run hot normally (linear voltage regulators, for example) and must be clamped to the heatsink to prevent them from overheating.
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