Need opinion on good 3000+ amp

[metalheadjoe 10+ year member]

I posted the quote from the Zed Audio manual that explains what it is, how it is calculated, and how that all goes out the window real world. It may or may not be in the part I cited but the manual also explains how to go about getting a very low output impedance when designing an amp and some reasons that the Far East class Ds have some issues getting a very low output impedance.

That's what is really baffling is that I posted the information right here in this thread and nobody seems to have taken the time to try to read and understand it.

Will you repost the info? I opened this thread today and landed on page 3 of 12, and I admittedly did not read the entire thread.

You are already highly regarded on this forum, so you gain nothing by being a prick.

 

[mat3833 10+ year member]

I posted the quote from the Zed Audio manual that explains what it is, how it is calculated, and how that all goes out the window real world. It may or may not be in the part I cited but the manual also explains how to go about getting a very low output impedance when designing an amp and some reasons that the Far East class Ds have some issues getting a very low output impedance.

That's what is really baffling is that I posted the information right here in this thread and nobody seems to have taken the time to try to read and understand it.

I've read the whole zed manual, I've also spoken at length to Stephen about how and why he does what he does when designing amps. My takeaway is pretty simple:

Most "signal" specifications provided on amps are irrelevant in the real world. Obviously this isn't counting RMS power, output current rating, crossover options/selection and to an extent signal-noise ratio.

Slew rate, damping factor, bandwidth, frequency response, all of these things can be measured in different ways, and nobody measures them in real world conditions with a real world install.

Amps and speakers work in conjunction with each other. The specific example I want to use here is damping factor (amp) vs inductance (subwoofer). An amp with a crazy high damping factor paired with a subwoofer with a very low Inductance would theoretically be the best possible match for reproducing the EXACT sine wave(s) of bass. Damping factor does jack **** in reality from my experience. Inductance however does have some effect.

For those unaware, inductance is the way we measure a coils resistance to voltage/current change. The higher the inductance the more resistant the coil is to "accepting" the change in voltage/current. Since speakers work off of AC power the coil is constantly being forced to accept a posative or negative charge. The lower inductance value helps the coil accept the change in its electromagnetic field faster, which leads to a quicker change in coil movement, which leads to more accurate reproduction of sound waves.

The same argument could be made for full bridge vs half bridge class D amps and their output filtering. Keeping it simple so I don't speak above my knowledge here, please overlook any over-simplification that's slightly off and focus on the main point. Half bridge class D amps use PWM switching to create their waveform so you must have good filters on the output section to avoid higher order noise generated from the PWM signal on the output that ends up as hiss or other noise when played through a tweeter. I can't recall the term but I beleive it's "ground referenced"? Full bridge amps need much less output filtering even tho they are also PWM driven. Since the amp produces both the positive and negative of the sine wave simultaneously the speaker doesn't "see" the noise because it acts like "balanced RCA's" and rejects anything not shared between posative rail and negative rail.

Does this make full bridge better than half bridge? Idk, depends on alot of factors. Theory doesn't directly translate to reality.

Matt

 

[Buck 5,000+ posts]

I've read the whole zed manual, I've also spoken at length to Stephen about how and why he does what he does when designing amps. My takeaway is pretty simple:

Most "signal" specifications provided on amps are irrelevant in the real world. Obviously this isn't counting RMS power, output current rating, crossover options/selection and to an extent signal-noise ratio.

Slew rate, damping factor, bandwidth, frequency response, all of these things can be measured in different ways, and nobody measures them in real world conditions with a real world install.

Amps and speakers work in conjunction with each other. The specific example I want to use here is damping factor (amp) vs inductance (subwoofer). An amp with a crazy high damping factor paired with a subwoofer with a very low Inductance would theoretically be the best possible match for reproducing the EXACT sine wave(s) of bass. Damping factor does jack **** in reality from my experience. Inductance however does have some effect.

For those unaware, inductance is the way we measure a coils resistance to voltage/current change. The higher the inductance the more resistant the coil is to "accepting" the change in voltage/current. Since speakers work off of AC power the coil is constantly being forced to accept a posative or negative charge. The lower inductance value helps the coil accept the change in its electromagnetic field faster, which leads to a quicker change in coil movement, which leads to more accurate reproduction of sound waves.

The same argument could be made for full bridge vs half bridge class D amps and their output filtering. Keeping it simple so I don't speak above my knowledge here, please overlook any over-simplification that's slightly off and focus on the main point. Half bridge class D amps use PWM switching to create their waveform so you must have good filters on the output section to avoid higher order noise generated from the PWM signal on the output that ends up as hiss or other noise when played through a tweeter. I can't recall the term but I beleive it's "ground referenced"? Full bridge amps need much less output filtering even tho they are also PWM driven. Since the amp produces both the positive and negative of the sine wave simultaneously the speaker doesn't "see" the noise because it acts like "balanced RCA's" and rejects anything not shared between posative rail and negative rail.

Does this make full bridge better than half bridge? Idk, depends on alot of factors. Theory doesn't directly translate to reality.

Matt

I think the noise maybe comes from the higher frequency mosfet gate switching to make the power steps with half-bridge output filtering. I think the full bridges are fundamentally cheaper with the way they’re built, because of the lack of need of more parts. They leave off a lot of that filter stuff on the full bridges on the output side.

This is what I meant by the pulsations and the power supplies:

There may be fluctuation balance in between the power supplies in the total circuit, which may lead to better production of the waveform (like damping)<-that’s a theory. The load is in between the two power supplies internally. I think the load being surrounded by mosfets in a full bridge can cause the amp to lose control of the sub, if the woofer is moving too much, on lows, for example. The woofer can unload into the power supply with half bridge, and that’s a part of damping factor, in my theory.

 

[hispls 5,000+ posts]

Will you repost the info?

http://zedaudiocorp.com/pdf/zedmanual-2013.pdf

Pages 2-16 would be well worth a read as there's a lot of good information there, or you can ctrl+f "damping factor" a couple times to just see the bits about that.

Most "signal" specifications provided on amps are irrelevant in the real world.

This seems very likely and it's been long known that a lot of specs we are given with loudspeakers are pretty well just marketing BS as well.

I have seen discussion about inductance being a thing with loudspeakers, and it's probably true, but I'm not sure how much weight I'd put on that. Really I think you're up against some hard realities there as far as building a loudspeaker that fulfills design goals if you start with some limitation on where your inductance can land.

 

[spokey9 5,000+ posts]

Everybody knows neither the amp or sub matter...it's all about the 8g remote wire

 

[hispls 5,000+ posts]

The woofer can unload into the power supply with half bridge, and that’s a part of damping factor, in my theory.

Damping factor is just the ratio of output imepdance of the amp to the impedance of your speaker. I can't imagine someone who knew what they were doing couldn't build a full bridge with a very low output impedance, in fact JL has been boasting some very large damping factor numbers on their slash series amps for like 20 years now.

 

[Buck 5,000+ posts]

Damping factor is just the ratio of output imepdance of the amp to the impedance of your speaker. I can't imagine someone who knew what they were doing couldn't build a full bridge with a very low output impedance, in fact JL has been boasting some very large damping factor numbers on their slash series amps for like 20 years now.

Yeah, but I didn’t say it wasn’t possible in a full bridge. I know there’s good full bridge amps, actually. I’m talking about the cheapest ways to make wattage available and what’s on the market lol. Circuitry pathways matter. I think that’s what you see in damping factor.

 

[mat3833 10+ year member]

I think the noise maybe comes from the higher frequency mosfet gate switching to make the power steps with half-bridge output filtering. I think the full bridges are fundamentally cheaper with the way they’re built, because of the lack of need of more parts. They leave off a lot of that filter stuff on the full bridges on the output side.

This is what I meant by the pulsations and the power supplies:

View attachment 40560

There may be fluctuation balance in between the power supplies in the total circuit, which may lead to better production of the waveform (like damping)<-that’s a theory. The load is in between the two power supplies internally. I think the load being surrounded by mosfets in a full bridge can cause the amp to lose control of the sub, if the woofer is moving too much, on lows, for example. The woofer can unload into the power supply with half bridge, and that’s a part of damping factor, in my theory.

Personally I've never had any low frequency issues on my taramps, I'm a low frequency guy. one of my go-to demo songs is "bass I love you" as well as "killshot" or "hood *****". I'm also not running half an ohm either, I've been running 4 ohm(d2 coil) or 2 ohm (2 D2 coils). Here soon I'll be running 5k to the pair of 5100's trunk baffle, so the only thing really controlling the cone is the motor/coil and signal.

Matt

 

[mat3833 10+ year member]

http://zedaudiocorp.com/pdf/zedmanual-2013.pdf

Pages 2-16 would be well worth a read as there's a lot of good information there, or you can ctrl+f "damping factor" a couple times to just see the bits about that.


This seems very likely and it's been long known that a lot of specs we are given with loudspeakers are pretty well just marketing BS as well.

I have seen discussion about inductance being a thing with loudspeakers, and it's probably true, but I'm not sure how much weight I'd put on that. Really I think you're up against some hard realities there as far as building a loudspeaker that fulfills design goals if you start with some limitation on where your inductance can land.

Inductance is something I've had experience with outside the audio world. The drive motors(40hp servo motors) for the CNC bridge have to be measured yearly. Inductance, resistance, holding current, etc all get measured. If inductance gets too high Fanuc will no longer stand behind their accuracy claims for that particular axis. The rest of the metrics are mainly a health check on the windings.

Speakers are complicated by nature. You have an electromagnetic suspension, a mechanical suspension and an air suspension all working together/against each other. The inductance value is only a small part of the equation.

From my experience, the subs I've ran with lower inductance (TC-1000 15's, pro 5100 18's) always felt more accurate. The best way I can explain it is violently accurate. Even at lower volumes, kick drums Smack you in the chest, low frequency notes just move you, and pitch changes feel instant. The JBL W15 GTIs I ran were awesome, but they weren't snappy and accurate until I threw tons of power to them.

I've ran a ton of different subs infinite baffle. That is pretty much the most demanding environment from a critical listening perspective. There isn't a box to help control the cone or alter the subs parameters. The suspension and motor do all the work and until now I haven't wanted to run anything else. If the sealed enclosure doesn't sound like I expect it too, I'm going to remove the back panel and run these subs in 31 cubic feet of "trunk baffle".

Matt

 

[hispls 5,000+ posts]

that’s what you see in damping factor.

Damping factor is the ratio of output impedance to your speaker impedance.

Speakers are complicated by nature. You have an electromagnetic suspension, a mechanical suspension and an air suspension all working together/against each other.

I've been told by a couple people in the industry that when we get into these huge super powerful motors that the motor is mostly the dominant factor in performance. For the most part you will find those 4hp platform subs will perform very similar regardless of suspension or cone and to some degree, even coil. Now perhaps if you get a really small WW coil you'll notice the difference, but is this due to inductance, or that you've now made it under-hung? Is the low inductance part of why a lot of folks swear by under-hung as sounding great? Really hard to test this since dramatically changing inductance requires dramatic change to the physical dimensions of the coil which will definitely effect other variables. Mostly I think low inductance on modern high powered subwoofers today is a pipe dream because the market demands enormous power handling which requires huge coil.

 

[mat3833 10+ year member]

Damping factor is the ratio of output impedance to your speaker impedance.



I've been told by a couple people in the industry that when we get into these huge super powerful motors that the motor is mostly the dominant factor in performance. For the most part you will find those 4hp platform subs will perform very similar regardless of suspension or cone and to some degree, even coil. Now perhaps if you get a really small WW coil you'll notice the difference, but is this due to inductance, or that you've now made it under-hung? Is the low inductance part of why a lot of folks swear by under-hung as sounding great? Really hard to test this since dramatically changing inductance requires dramatic change to the physical dimensions of the coil which will definitely effect other variables. Mostly I think low inductance on modern high powered subwoofers today is a pipe dream because the market demands enormous power handling which requires huge coil.

This **** right here is the importance of using your knowledge to draw your own conclusions! Hell, if I had the cash I'd send you the beehive motors so you could build 2 tops with different inductance just to get more information. I 100 percent agree that motor force is the dominant factor once you get above a certain power threshold. High motor force + lightweight MMS = accurate reproduction.

I never really considered that underhung drivers tend to be the low inductance drivers. How do you think making some crazy quad 4 ohm coil underhung driver would affect things? Each "coil" would have a low ish inductance, and you could wire it to 1ohm. Copper coil for this example, I'm not a fan of aluminum coils personally.

 

[Buck 5,000+ posts]

Personally I've never had any low frequency issues on my taramps, I'm a low frequency guy. one of my go-to demo songs is "bass I love you" as well as "killshot" or "hood *****". I'm also not running half an ohm either, I've been running 4 ohm(d2 coil) or 2 ohm (2 D2 coils). Here soon I'll be running 5k to the pair of 5100's trunk baffle, so the only thing really controlling the cone is the motor/coil and signal.

Matt

Taramps seem to be a solid design. That’s one of the amps that just seems to work compared to others, but only from what I’ve seen.

Damping factor is the ratio of output impedance to your speaker impedance.

I get that. Idk why you keep saying that over and over. Are you saying the way the amp is wired internally has no effect on output impedance? What am I saying that’s actually wrong? Output impedance on the amp changes the way the energy flows internally in the amp, and so does the circuitry pathways in the full vs half bridge design. Effective damping changes with frequency. If your sub tries to unload into mosfets with a full bridge, where a half bridge can seemingly use the larger capacity power supply system, does that not change the nature of the damping factor? Is it not easier to overload a mosfet than a power supply, especially on the cheapest made amps/individual components with both half and full bridges?

 

[Buck 5,000+ posts]

I 100 percent agree that motor force is the dominant factor once you get above a certain power threshold. High motor force + lightweight MMS = accurate reproduction.

I totally agree with that. When you combine that thought + good box design, you can get a really solid reproduction of the waveform. That’s why I look at damping factor as a cone-movement-control factor. The box plays maybe the biggest role in controlling frequency-related stress on the amp, but it really depends on what you’re doing. Like some DC 4” coils (and other monsters) have a massive Mms and strong motors, and if you’re playing super lows and the sub is moving a lot or unloading with like 40mm of xmax or more, that’s a ton of energy trying to go back into the amp, basically. If that energy isn’t dispersed or handled properly, you can get a heavily distorted waveform or go into some circuit protect situation from something like drawing too much power to control the sub, when the amp doesn’t have enough capacity to deal with being hammered (electrically) by the massive coil movement. That seems to be why amps go into circuit protect, sometimes, if you play too low for your ported box.

 

[hispls 5,000+ posts]

Idk why you keep saying that over and over.

Because you keep lumping in all sorts of random ideas into this.

so does the circuitry pathways in the full vs half bridge design

So if full bridge is the i ssue here, how come JL advertises damping factor of 1000 on their slash series amps?

Effective damping changes with frequency.

The ratio of input impedance to speaker impedance improves as you move away from z-min of the system, but this doesn't change "damping factor" which is just output impedance vs. some nominal load value.

if you’re playing super lows and the sub is moving a lot or unloading with like 40mm of xmax or more, that’s a ton of energy trying to go back into the amp, basically. If that energy isn’t dispersed or handled properly, you can get a heavily distorted waveform or go into some circuit protect situation from something like drawing too much power to control the sub, when the amp doesn’t have enough capacity to deal with being hammered (electrically) by the massive coil movement.

Where are you coming up with this stuff?

 

[Buck 5,000+ posts]

Because you keep lumping in all sorts of random ideas into this.

So if full bridge is the i ssue here, how come JL advertises damping factor of 1000 on their slash series amps?

The ratio of input impedance to speaker impedance improves as you move away from z-min of the system, but this doesn't change "damping factor" which is just output impedance vs. some nominal load value.


Where are you coming up with this stuff?

I said effective damping factor…the ability for the amp to dampen anything is going to be frequency related. So impedance ratios don’t change? Wouldn’t both the output impedance and speaker impedance change independently of each other while the sub is playing music? As in, does the damping factor of the system stay the same at electrically producing 20 Hz as it does at 20,000 Hz?

I didn’t say full bridge was the issue in that context man, come on. The JL isn’t made with cheapest components out there. You’re totally like ignoring my whole main point of cheap versions of full bridges vs half. Is 1000 damping factor an indicator of that JL amp’s quality? Or is it totally f*cking irrelevant? You’re not being fair here.