ProSoundWeb Community

Please login or register.

Login with username, password and session length
Advanced search  

Pages: 1 2 3 [4] 5   Go Down

Author Topic: 21" subwoofers - opinions  (Read 10806 times)

Ivan Beaver

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 9077
  • Atlanta GA
Re: 21" subwoofers - opinions
« Reply #30 on: February 26, 2017, 09:27:31 am »

Ivan you are correct, at least on line they are rated at more than 30V/microsecond , and some models at 13V/microsecond. I had all my gear stolen in 1997, and I could swear that is what the manual said. I suspect dementia.

But to use your words, "it depends" :()

I don't know how you tested the amps, but remember that when you bridge an amp, damping factor goes to 1/2 value, and also at what frequency was the number obtained.
Damping factor values at 400Hz should not be compared to a 40Hz measurements, where the cone movement has a much lower inertia, and  it is so much easier to apply the "breaks"  (damping factor) before the cone reverses direction. But then again, you already know all that.
I remember "Back in the day" that Crown was ridiculed for having such a low slew rate.

But it did  not hurt the popularity-nobody seemed to notice.

All of my tests were done single channel.

Agreed the damping factor goes in half when bridged.

That is because the output channels are in series with each other-so the "total loop resistance" is doubled-at least for the amplifier part.
Logged
A complex question is easily answered by a simple-easy to understand WRONG answer!

Ivan Beaver
Danley Sound Labs

PHYSICS- NOT FADS!

John Ferreira

  • Full Member
  • ***
  • Offline Offline
  • Posts: 150
Re: 21" subwoofers - opinions
« Reply #31 on: February 26, 2017, 02:04:19 pm »

I remember "Back in the day" that Crown was ridiculed for having such a low slew rate.

But it did  not hurt the popularity-nobody seemed to notice.

All of my tests were done single channel.

Agreed the damping factor goes in half when bridged.

That is because the output channels are in series with each other-so the "total loop resistance" is doubled-at least for the amplifier part.

Technically, impedance and not just resistance.
Logged
John Ferreira

Ivan Beaver

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 9077
  • Atlanta GA
Re: 21" subwoofers - opinions
« Reply #32 on: February 26, 2017, 02:13:36 pm »

Technically, impedance and not just resistance.
I would "argue" that the output stage of an amp is probably much more resistive than inductive or capacitive. 

But I have to admit, I have never measure the phase of the output "impedance" of an amp, which would tell if it had an "impedance character".

So I could be wrong.

But I guess if the phase was even a couple of degrees off, it would be considered impedance.
Logged
A complex question is easily answered by a simple-easy to understand WRONG answer!

Ivan Beaver
Danley Sound Labs

PHYSICS- NOT FADS!

John Ferreira

  • Full Member
  • ***
  • Offline Offline
  • Posts: 150
21" subwoofers - opinions
« Reply #33 on: February 26, 2017, 08:51:19 pm »

I would "argue" that the output stage of an amp is probably much more resistive than inductive or capacitive. 

But I have to admit, I have never measure the phase of the output "impedance" of an amp, which would tell if it had an "impedance character".

So I could be wrong.

But I guess if the phase was even a couple of degrees off, it would be considered impedance.

Yes, but you love the correct numbers (   :)   ) and the amp "sees" an inductive reactive load, like a dancing moving target, and frequency dependent, plus the physical coil resistance. Since you love accuracy, when  you have inductive reaction plus resistance, it's then called impedance. But feel free to correct me.
« Last Edit: February 26, 2017, 08:54:54 pm by John Ferreira »
Logged
John Ferreira

Ivan Beaver

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 9077
  • Atlanta GA
Re: 21" subwoofers - opinions
« Reply #34 on: February 26, 2017, 08:57:01 pm »

Yes, but you love the correct numbers (   :)   ) and the amp "sees" an inductive reactive load, like a dancing moving target, and frequency dependent. Since you love accuracy, when  you have inductive reaction plus resistance, it's then called impedance. But feel free to correct me.
Yes-it depends on how things are "defined"

Since resistance is "basically" described as the opposition of flow to DC, and impedance is described as the opposition of flow to AC, then I "guess" it could be described as impedance-even if there is no reactive component in the actual value.

I am certainly not an expert in that specific regard, so could easily be wrong and would welcome correction.
Logged
A complex question is easily answered by a simple-easy to understand WRONG answer!

Ivan Beaver
Danley Sound Labs

PHYSICS- NOT FADS!

John Ferreira

  • Full Member
  • ***
  • Offline Offline
  • Posts: 150
21" subwoofers - opinions
« Reply #35 on: February 27, 2017, 09:16:55 am »

Lol! I've read here how you love the words "it depends".
I am not an expert either, and my electronics courses are ancient from 1984. I'm still learning everyday, and specially from people like you.

Like I said, I was just being technical (and picky)
Just trying to stay in context, since we are talking mostly about sound and the effect of the damping factor on bass response, we are in the realm of AC.

Your statement about DC not being affected by impedance, again, "technically", if you have a variable DC, impedance will very much be a factor.
« Last Edit: February 27, 2017, 10:40:49 am by John Ferreira »
Logged
John Ferreira

Jay Barracato

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 2025
  • Solomons, MD
Re: 21" subwoofers - opinions
« Reply #36 on: February 28, 2017, 04:42:04 pm »

My truck has a 4.11 to 1 rear differential. Can you tell me what performance I can expect?

Sent from my XT1254 using Tapatalk

Logged
Jay Barracato

Tim McCulloch

  • SR Forums
  • Hero Member
  • *
  • Offline Offline
  • Posts: 21633
  • Wichita, Kansas USA
Re: 21" subwoofers - opinions
« Reply #37 on: February 28, 2017, 07:45:59 pm »

My truck has a 4.11 to 1 rear differential. Can you tell me what performance I can expect?

Sent from my XT1254 using Tapatalk

With how may wheels at a time, and will red paint make my truck into a sports car?  You don't want to leave out anything, Jay!
Logged
"Practicing an art, no matter how well or badly, is a way to make your soul grow, for heaven's sake. Sing in the shower. Dance to the radio. Tell stories. Write a poem to a friend, even a lousy poem. Do it as well as you possible can. You will get an enormous reward. You will have created something."  - Kurt Vonnegut

John Ferreira

  • Full Member
  • ***
  • Offline Offline
  • Posts: 150
21" subwoofers - opinions
« Reply #38 on: March 01, 2017, 09:33:36 am »

My truck has a 4.11 to 1 rear differential. Can you tell me what performance I can expect?

Sent from my XT1254 using Tapatalk
Again it depends how much you weigh, and bigger is not better.
« Last Edit: March 01, 2017, 09:39:16 am by John Ferreira »
Logged
John Ferreira

Teddy Murphy

  • Jr. Member
  • **
  • Offline Offline
  • Posts: 76
Re: 21" subwoofers - opinions
« Reply #39 on: March 04, 2017, 09:44:18 am »

Message me if you have any questions.  I own 4 618xlf and 8 of the 1521s as well as 8 s30. I have used them all for different applications. 
Logged

ProSoundWeb Community

Re: 21" subwoofers - opinions
« Reply #39 on: March 04, 2017, 09:44:18 am »


Pages: 1 2 3 [4] 5   Go Up
 



Page created in 0.068 seconds with 23 queries.