ProSoundWeb Community

Please login or register.

Login with username, password and session length
Advanced search  
Pages: [1] 2 3 ... 10   Go Down

Author Topic: Crest Pro 8200 amps  (Read 36863 times)

Alan Sledzieski

  • Full Member
  • ***
  • Offline Offline
  • Posts: 159
Crest Pro 8200 amps
« on: July 18, 2010, 10:38:19 AM »

 I recently bought 2 pro 8200 amps to use on sub duty.  The amps replaced 4 crest vs 1500's, each bridged into 8 ohms. The Vs amps were 12 rack spaces, 6kw, 160 lbs. The pro 8200's are 4 rack spaces, 9 kw, 40 lbs.

The 8200's worked and sounded great.  For amps with damping factor of only 300, and a slew rate of 10 vms they sounded great. Shows me specs don't mean everything.

I also ran the 8200's near clip all night, hit the acl  once in a while.  I did this on 1 20 amp circuit, the amps are plugged into a furman ar 1215 regulator, max output of the reg is 13.5 amps, no problems tripping the reg.  So I don't understand how crest comes up with the huge power consumption values

I use 2 ca9's bridged on the top when needed, usually just 1 in stereo for most shows. ( I'm a weekend warrior, small venues compared to most on here, 100 to 200 people )

Thinking about 1 9200 on top, and 2 more double 18's on the bottom.

Anyone selling 8200's and a 9200 let me know.

Now I have to sell 4 vs 1500's
Logged

Ivan Beaver

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 9010
Re: Crest Pro 8200 amps
« Reply #1 on: July 18, 2010, 10:55:17 AM »

It is REAL hard to come up with power consumption numbers when dealing with a dynamic source-such as music.

You also have to consider that the breaker will not trip with short bursts of high current draws.

So you may be pulling a good bit more than you think.

Breakers trip with current draw over time (ie heating), just like loudspeakers.  They can take a lot for a short period of time-but as the average goes up, you get closer to the damage/trip point.
Logged
For every complicated question-there is a simple- easy to understand WRONG answer.

Can I have some more talent in the monitors--PLEASE?

Ivan Beaver
dB Audio & Video Inc.
Danley Sound Labs

Alan Sledzieski

  • Full Member
  • ***
  • Offline Offline
  • Posts: 159
Re: Crest Pro 8200 amps
« Reply #2 on: July 18, 2010, 11:04:06 AM »

Ivan Beaver wrote on Sun, 18 July 2010 10:55

It is REAL hard to come up with power consumption numbers when dealing with a dynamic source-such as music.

You also have to consider that the breaker will not trip with short bursts of high current draws.

So you may be pulling a good bit more than you think.

Breakers trip with current draw over time (ie heating), just like loudspeakers.  They can take a lot for a short period of time-but as the average goes up, you get closer to the damage/trip point.



I understand that, ( I'm a electrical lineman ).  We just got done with 5 days near 90, transformers were fine the first day and a half, after a night where they did not cool down they started tripping.  I had a few 25 kva transformers that tripped that were loaded to 45 kva, and you could cook eggs on them, LOL.

 What gets me is the ar 1215 has a fast acting breaker, so it says.  Previous to the 8200 amps, I was running 3 1500's near clip all night, on 1 ar 1215  
Logged

Bennett Prescott

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 8924
    • http://www.adraudio.com
Re: Crest Pro 8200 amps
« Reply #3 on: July 20, 2010, 02:47:43 PM »

Alan Sledzieski wrote on Sun, 18 July 2010 10:38

The 8200's worked and sounded great.  For amps with damping factor of only 300, and a slew rate of 10 vms they sounded great. Shows me specs don't mean everything.

Both of those specs don't mean anything. Here's an article on damping factor, someone more electrically smart than I can tell you about slew rate:

http://www.bennettprescott.com/downloads/dampingfactor.pdf
Logged
-- Bennett Prescott
Director of North American Sales
ADRaudio d.o.o.
Cell: (518) 488-7190

"Give me 6dB and I shall move the world." -Archimedes

John Roberts {JR}

  • Newbie
  • *
  • Offline Offline
  • Posts: 0
Re: Crest Pro 8200 amps
« Reply #4 on: July 20, 2010, 03:09:42 PM »

Alan Sledzieski wrote on Sun, 18 July 2010 09:38

 

The 8200's worked and sounded great.  For amps with damping factor of only 300, and a slew rate of 10 vms they sounded great. Shows me specs don't mean everything.




No specs mean something, but more of anything beyond what you need is not automatically better, despite what some marketing types will want you to believe.

15 v/usec (per a magazine review I found) is adequate to deliver a >40kHz (full) power bandwidth. More than adequate for any audio application I can think of. What's more important than max slew rate is how the input stage handles out of band signals. I would expect Crest did this correctly.

I have written extensively here about slew rate, and in fact consider a properly designed audio path to be rise time limited, not slew limited. If you want my full lecture, do a search.

Note: consumers are simple souls who prefer simple specs like slew rate over rise time, so amp manufacturers give the consumers what they want, since they are in truly in charge (and always right).

JR
Logged
 https://www.resotune.com/


Tune it, or don't play it...
-----

Art Welter

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 4874
Re: Crest Pro 8200 amps
« Reply #5 on: July 20, 2010, 07:12:55 PM »

Alan Sledzieski wrote on Sun, 18 July 2010 09:04

Ivan Beaver wrote on Sun, 18 July 2010 10:55

It is REAL hard to come up with power consumption numbers when dealing with a dynamic source-such as music.

You also have to consider that the breaker will not trip with short bursts of high current draws.

So you may be pulling a good bit more than you think.

Breakers trip with current draw over time (ie heating), just like loudspeakers.  They can take a lot for a short period of time-but as the average goes up, you get closer to the damage/trip point.


 What gets me is the ar 1215 has a fast acting breaker, so it says.  Previous to the 8200 amps, I was running 3 1500's near clip all night, on 1 ar 1215  

Going by the  Crest 8200 1/8 th power specification of 1875 watts at 2 ohm, 1250 watts at 4 ohm, at that ratio 8 ohm loading would be 833 watts, x 2 would be 1666 watts/120 is 13.88 amps.
The manual says the 1215 regulator uses a 15 amp fast blow circuit breaker.
If you figure it’s maximum continuous output is 13.5 amps, you may be pretty close to it’s limit.
Logged

Alan Sledzieski

  • Full Member
  • ***
  • Offline Offline
  • Posts: 159
Re: Crest Pro 8200 amps
« Reply #6 on: July 20, 2010, 08:29:08 PM »

Dampning factor.  I did read a topic on that and saw that the wire resistance is also included, amazed at how everything worked out to a very low value.

As a weekend warrior i run small venues, 25 feet is a big spread for my subs so I run very short lengths.

Slew rate. I'll have to look that up and do some research.

I'm very big into snowmobiling and modded out engines.  Ben on a dyno many a time.  There are certain things that individual companies can post hp. and torque numbers that seem great on paper, but actually not good in the field.  Numbers sell, thats why I tune on a independent dyno that gives real world numbers.

I'm beginning to see the same in the amp specs.  Specs don't always mean everything.  My vs 1500's sound great, but are very heavy, My ca9's sound great, but are very heavy.

I put the 8200's on the bottom end and was very pleased, even with some specs that are not close to that of a vs or ca.

I have tried many amps, never any of the crown macros, or itechs.  I have yet to hear a better amp then a crest.  They just seem uncolored, like its not there, very natural.

I have 2 more 8200's coming, as I will be building 2 more double 18 box's.  I still want a 9200 for the jbl 4733's. I'll keep the 2 ca9's I have for monitors, and loose the vs 1500's.

A friend of mine who also was a crest fan wanted something lighter, he bought crown xti amps, specs looked good, they may be the worst amps we, I ever heard on the bottom end.

Logged

Alan Sledzieski

  • Full Member
  • ***
  • Offline Offline
  • Posts: 159
Re: Crest Pro 8200 amps
« Reply #7 on: July 20, 2010, 08:36:08 PM »

As far as the regulator, / power consumption.

I did a show a few weeks ago, 115v into the ar 1215.  I ran 3 vs 1500's at just tickling the acl light all night.  So if i only had 13.5 amps available with a ar 1215, I don't see how they amp manufactures come up with power draw.

What I need to do is make a 12'' extension cord, with the hot and neutral apart from each other, put a digital clamp on amp meter on the hot leg, or neutral, and see whats actually going on.
Logged

Tim McCulloch

  • Newbie
  • *
  • Offline Offline
  • Posts: 0
Re: Crest Pro 8200 amps
« Reply #8 on: July 21, 2010, 01:19:47 AM »

The real lesson is that numbers don't make sound.

Logged
"Will you stand by me against the cold night, or are you afraid of the ice?" Crack The Sky

Tim McCulloch

  • Newbie
  • *
  • Offline Offline
  • Posts: 0
Re: Crest Pro 8200 amps
« Reply #9 on: July 21, 2010, 01:26:49 AM »

Alan Sledzieski wrote on Tue, 20 July 2010 19:36

As far as the regulator, / power consumption.

I did a show a few weeks ago, 115v into the ar 1215.  I ran 3 vs 1500's at just tickling the acl light all night.  So if i only had 13.5 amps available with a ar 1215, I don't see how they amp manufactures come up with power draw.

What I need to do is make a 12'' extension cord, with the hot and neutral apart from each other, put a digital clamp on amp meter on the hot leg, or neutral, and see whats actually going on.


As has been pointed out, with a dynamic signal like music, your measurement will be in vane.  The major amp manufacturers have current draw specifications for various duty cycles.  Pink noise with a 6db crest factor, with the peaks at hard clipping represents a 50% duty cycle.  I doubt your use is that intensive, so I suggest you look at the 1/8 and 1/3 duty cycles and either pick an average of them, or just go with the 1/3 duty cycle rating as the maximum you are likely to draw.

You don't need any type of "regulator" on the power amps.  Use it on something else, like console and outboard gear.

Have fun, good luck.

Tim Mc
Logged
"Will you stand by me against the cold night, or are you afraid of the ice?" Crack The Sky
Pages: [1] 2 3 ... 10   Go Up
 

Site Hosted By Ashdown Technologies, Inc.

Page created in 0.037 seconds with 17 queries.