Amp Clipping Issue

[jinjuku]

I think you may be attributing a characteristic of a specific design implementation to a topology, when in fact they are separate issues. It is possible to design an amp with high dynamic headroom using any topology, but it may be more cost effective in certain ones. There's no reason a class D amp couldn't be designed with high dynamic headroom, but it may be more cost effective to just build in a higher maximum peak power than to try to do it dynamically.

Your second half of response mirrors what I have heard previously. The other thing I have heard is do to the nature of how quickly the line voltage can be tapped that Class D can have a positive impact on lower register audio.

 

[avengineer]

The other thing I have heard is do to the nature of how quickly the line voltage can be tapped that Class D can have a positive impact on lower register audio.

The "lower register" wouldn't be the part of the spectrum that requires speed. The class D topology, by definition, has to be band-limited just to to function, there's no reason to think it can tap line voltage any faster than other topologies. Class D's advantage is efficiency due to operating the output devices in switch-mode. So that one is probably myth.

 

[avengineer]

OK, I probably didn't write that one very well...
The demands Class D makes on the DC supply is a train of high frequency pulses of varying widths, so the DC supply design has to be different. But the DC rail is still removed from the line by at least a stage of isolation and filtering. The speed at which the supply can recover from a high demand is still a factor, as in all topologies. The fact that a high demand still has the high frequency switching component in it only makes the supply filter a bit more tricky.

Just to be clear, there's nothing "fast" about bass, it's demands on an amp and supply change more slowly than a high frequency component, even in switch-mode.

 

[AcuDefTechGuy]

It's the one right after the multiple lightning strikes when everyone is looking at the ground. When everything starts cracking and falling apart as the machine comes out of the ground is when the limiter engaged.

I checked out the scenes last night. Amazing scary bass for sure. Made me a little anxious. But no problem at all with my Funk 18.0 subs or AT3002 amp.

I tried watching the rest of the movie.


Besides the fabulous bass, I thought this movie was pretty stupid. Bad acting, bad directing, just really dumb movie IMO.

 

[PENG]

I think you may be attributing a characteristic of a specific design implementation to a topology, when in fact they are separate issues. It is possible to design an amp with high dynamic headroom using any topology, but it may be more cost effective in certain ones. There's no reason a class D amp couldn't be designed with high dynamic headroom, but it may be more cost effective to just build in a higher maximum peak power than to try to do it dynamically.

I can agree to that, and I wouldn't worry about headroom if I had one of those Bel Canto class D monoblock.

 

[jinjuku]

OK, I probably didn't write that one very well...
The demands Class D makes on the DC supply is a train of high frequency pulses of varying widths, so the DC supply design has to be different. But the DC rail is still removed from the line by at least a stage of isolation and filtering. The speed at which the supply can recover from a high demand is still a factor, as in all topologies. The fact that a high demand still has the high frequency switching component in it only makes the supply filter a bit more tricky.

Just to be clear, there's nothing "fast" about bass, it's demands on an amp and supply change more slowly than a high frequency component, even in switch-mode.

Who knows. I'm certainly not making any claims and holding fast to them What I do know is my DriveCore does a really good job and is quiet.

 

[RichB]

I checked out the scenes last night. Amazing scary bass for sure. Made me a little anxious. But no problem at all with my Funk 18.0 subs or AT3002 amp.

I tried watching the rest of the movie.


Besides the fabulous bass, I thought this movie was pretty stupid. Bad acting, bad directing, just really dumb movie IMO.

What BD are you folks talking about?
I want to play too

- Rich

 

[RichB]

OK, I probably didn't write that one very well...
The demands Class D makes on the DC supply is a train of high frequency pulses of varying widths, so the DC supply design has to be different. But the DC rail is still removed from the line by at least a stage of isolation and filtering. The speed at which the supply can recover from a high demand is still a factor, as in all topologies. The fact that a high demand still has the high frequency switching component in it only makes the supply filter a bit more tricky.

Just to be clear, there's nothing "fast" about bass, it's demands on an amp and supply change more slowly than a high frequency component, even in switch-mode.

Isn't all about supplying the current and damping required by the speaker load?

I tried a D-Sonic when they were ICE based and there was something about the sound I did not like.
I did not like the bass performance with my Revel Salons. The Outlaw, ATI, and Parasound drive them very well.

If I were in the market for a muscle amp right now, I would look at the Emotiva XPR line.
The rail switching gives efficiency and you cannot beat the price.
All the bling you desire and you can turn it off if you don't

- Rich

 

[panteragstk]

What BD are you folks talking about?
I want to play too

- Rich

War of the Worlds. Great bass, crappy movie. If you want to watch an entire film of Dakota Fanning whining then you've found it.

I did another experiment today. Since I rewired the subs from 2 ohms to 8 ohms, I decided to see what the amp could do in 4 ohm bridged mode. Same output as 2 ohms stereo (1550w mono as opposed to 775w stereo). This time it didn't clip/peak limit. Interesting. It would seem that this amp loves to spit out gobs of power, but not a 2 ohms stereo. I'll say this though, there aren't very many amps that can output that much power at 2 ohms without crapping out, so for the $250 I paid for this thing I couldn't be happier.

I did find the excursion limits of the drivers today. I played the scene in Pulse where she goes down into the basement (1 hr 11 min) and it has a fairly quick continuous sweep from 15hz to 20hz and boy were those things moving.

I paid $60 each for them so I'm not surprised that I finally found their limit. Now I need to decide on what to replace them with.

I'm looking at the following:

Infinity Kappa 120.9w for $145 ea
TC sounds Epic 12" for $193 ea (a bit higher xmax that the 120.9w. 18.1 mm epic vs. 17.5mm kappa. 500w RMS epic vs. 350w RMS kappa)
TC LMS-R 12" for $340 ea (I'd need another amp for these. 1000w RMS. 25.4 mm xmax)
Fi Q12" for $285 (would also need an additional amp. 1500w RMS. 28mm xmax)

Obviously the LMS-R 12" would be the one I want, but I'd have to wait a while to get it due to some other financial obligations I have (new furniture, etc).

Thoughts?

 

[RichB]

Other movies that come to mind for their LFE:

- Jurassic Park
- Close Encounter (I woke my wife up who thought house was coming apart )
- Super 8 - just because

- Rich

 

[AcuDefTechGuy]

War of the Worlds. Great bass, crappy movie. If you want to watch an entire film of Dakota Fanning whining then you've found it.

OMG. So true.

Loved the bass, but I was thinking, "Steven Spielberg sucks!".

The ground is breaking, the buildings crumbling, the giant alien awakens, but, no, I am just going to stare at it and see what happens.

And 100 cars are all parked on the sides of the road so that Tom Cruise is the ONLY one trying to get the hell out of there.

We could go on and on.

But awesome bass for sure. Good bass torture test.

 

[AcuDefTechGuy]

Other movies that come to mind for their LFE:

- Jurassic Park
- Close Encounter (I woke my wife up who thought house was coming apart )
- Super 8 - just because

- Rich

A movie with great bass that is actually intelligent is "Inception". Christopher Nolan makes Spielberg look amateur.

 

[RichB]

A movie with great bass that is actually intelligent is "Inception". Christopher Nolan makes Spielberg look amateur.

I have that one. Time to watch it

- Rich