Damping Factor - Actual listening tests?

Re: Damping Factor - Actual listening tests?

Jim McKeveny said:
Now that we have exhausted the (mostly academic) modern, in-practice irrelevance of Damping Factor, can we now revisit Slew Rate?
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What I find funny in that, is that the amp series with one of the worst slew rates ever, is/was the most respected and rider accepted amp.

The Crown MA series.

You don't see them in studios, but if slew rate was something to be concerned with, this amp should be at the bottom of everybodys list.

Of course we could also talk about distortion. OH 0.001 is much less distortion than 0,01%

Never mind the fact that most people can't even recognize/hear distortion until it get well past 1%.

But they "think" it will sound better with lower distortion. Technically they are correct-but it makes no difference in the end.

We can measure all kinds of things our ears cannot hear.

And if you think you ears are hearing something "that can't be measured", then you are measuring the WRONG thing.

WAY to many people think a 1/3rd RTA will tell them everything they need to know about a piece of gear-WRONG!

Getting off soap box now.
 
Re: Damping Factor - Actual listening tests?

Jim McKeveny said:
Now that we have exhausted the (mostly academic) modern, in-practice irrelevance of Damping Factor, can we now revisit Slew Rate?
Click to expand...

8O~8-O~:shock: .... Its in exactly the same boat as damping factor. Modern semiconductor are fast and its not an issue in 2015 .... even class D amplifiers sound good now.
 
Re: Damping Factor - Actual listening tests?

Ivan Beaver said:
What I find funny in that, is that the amp series with one of the worst slew rates ever, is/was the most respected and rider accepted amp.

The Crown MA series.

You don't see them in studios, but if slew rate was something to be concerned with, this amp should be at the bottom of everybodys list.

Of course we could also talk about distortion. OH 0.001 is much less distortion than 0,01%

Never mind the fact that most people can't even recognize/hear distortion until it get well past 1%.

But they "think" it will sound better with lower distortion. Technically they are correct-but it makes no difference in the end.

We can measure all kinds of things our ears cannot hear.

And if you think you ears are hearing something "that can't be measured", then you are measuring the WRONG thing.

WAY to many people think a 1/3rd RTA will tell them everything they need to know about a piece of gear-WRONG!

Getting off soap box now.
Click to expand...

Yeah ... but they were faster than the Phase Linear's and about twice as fast as the Crown DC300, which was considered a laboratory spec amp in its day. Old output devices were slow.
 
Re: Damping Factor - Actual listening tests?

Peter Morris said:
Yeah ... but they were faster than the Phase Linear's and about twice as fast as the Crown DC300, which was considered a laboratory spec amp in its day. Old output devices were slow.
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I really don't want to go around this old tree again, but the speed of the DC300 was compromised even further by the quasi-complementary output stage topology. Fast and rugged PNPs were not widely available way back then, so the DC300 used NPN power devices to both pull up and pull down. To make the NPN power device act like a PNP, a smaller PNP was connected in a darlington connection to make the compound device behave like a power PNP. This mixed darlington is slower than a same polarity darlington, so the overall amplifier stability compensation had to be slow enough to accommodate the slower half of this quasi-complementary output stage.

The DC300 delivered respectable performance when new back in the day... I was not a fan of replicating the old schematic almost verbatim, while using SMD and newer plastic power devices (but using the same old tired topology) to make the CE1000/2000 amps. Some sharp pencil bean counter probably got a raise for that (no actual design engineers were stressed) project. :-(

JR
 
Re: Damping Factor - Actual listening tests?

My post was sarcastic, aimed at wise veterans of amp spec wars. Perhaps the snark didn't translate to text well.
 
Re: Damping Factor - Actual listening tests?

Jim McKeveny said:
Never a fan. Iffy mechanical design and "maintenance sensitive" for touring (filters+microfin sinks). And how exactly does one understand the display?
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MA's don't have displays.... Not sure if you were attempting another swing at sarcasm....but it was a miss.
 
Re: Damping Factor - Actual listening tests?

Jim McKeveny said:
Never a fan. Iffy mechanical design and "maintenance sensitive" for touring (filters+microfin sinks). And how exactly does one understand the display?
Click to expand...

The only display is the front panel LEDs.

The ODEP are basically peak lights and temp indicators.

They glow brighter when max output is obtained.

If they start to dim down, then that means the amp is getting hot and it is reducing the level to help protect itself.

Yes the filters do get clogged up, but then again-so do all amps with fans and filters.

They are easily cleaned.

THe microfin heatsinks are actually quite effective. There is a lot of surface area, and they cool down quickly (due to the small mass) as compared to large heavy heatsinks. Of course they also heat up quicker-------

The MA was pretty much the industry "standard" for a couple of decades, and people still swear by them (all but the 3600)
 
Re: Damping Factor - Actual listening tests?

Ivan Beaver said:
The only display is the front panel LEDs.
They glow brighter when max output is obtained.
Click to expand...

As I said, such a definitive display! Harkens back to the 24v lamps that some soundco's placed across the DC300A outputs.

Old school extruded sinks on a tunnel were much more reliable for dusty outdoor gigs, at the cost of rack space.

The 3600 was 10lbs of guano in a 5lb bag. Similar fate for Crest 9001. A little to much dust, a little too much humidity and blooey!
 
Re: Damping Factor - Actual listening tests?

Jim McKeveny said:
As I said, such a definitive display! Harkens back to the 24v lamps that some soundco's placed across the DC300A outputs. I like my power indicators in db not lumens.

Old school extruded sinks on a tunnel were less troublesome than microfins for dusty/musty outdoor (sometimes indoor) gigs of the day, granted at the cost of rack space. Even with daily maintenance, by the time the headliner took the stage the BTU cooling cap was significantly down.

The 3600 was 10lbs of guano in a 5lb bag. Similar fate for Crest 9001. A little to much dust, a little too much humidity and blooey!
Click to expand...

k?
 
Re: Damping Factor - Actual listening tests?

Ivan Beaver said:
What I find funny in that, is that the amp series with one of the worst slew rates ever, is/was the most respected and rider accepted amp.

The Crown MA series.

You don't see them in studios, but if slew rate was something to be concerned with, this amp should be at the bottom of everybodys list.

Of course we could also talk about distortion. OH 0.001 is much less distortion than 0,01%

Never mind the fact that most people can't even recognize/hear distortion until it get well past 1%.

But they "think" it will sound better with lower distortion. Technically they are correct-but it makes no difference in the end.

We can measure all kinds of things our ears cannot hear.

And if you think you ears are hearing something "that can't be measured", then you are measuring the WRONG thing.

WAY to many people think a 1/3rd RTA will tell them everything they need to know about a piece of gear-WRONG!

Getting off soap box now.
Click to expand...

Slew rate by itself isn't even a useful figure. Combine it with max voltage swing and the highest frequency the amp needs to reproduce, and you've sorta got something. Even if it's pretty irrelevent.
 
Re: Damping Factor - Actual listening tests?

Bob Lee said:
Slew rate by itself isn't even a useful figure. Combine it with max voltage swing and the highest frequency the amp needs to reproduce, and you've sorta got something. Even if it's pretty irrelevent.
Click to expand...

And a pretty low number, too. But that doesn't fit the marketing spin...
 
Re: Damping Factor - Actual listening tests?

Jim McKeveny said:
As I said, such a definitive display! Harkens back to the 24v lamps that some soundco's placed across the DC300A outputs.
Click to expand...
I have never heard of putting lamps across the amp outputs.

That seems pretty stupid to me-since in the cold state, they are close to a short. Solid state amps don't like that.

But assuming that was not an issue, the light would glow brighter with greater output, making it hard to tell what the actual level was.

The ODEPs would be at one state for normal signals, and then go to a brighter state when the threshold was exceeded.

It made it real easy to see. But a separate LED would have been better.

I used to run a number of MAs (1200, 2400, 5000s) and never had a problem with the "display" or the dust filters. Just clean them every so often and they are fine.

I never had my heatsinks clog up.

I don't ever recall a failure of one of mine.
 
Re: Damping Factor - Actual listening tests?

I thought this dog was sleeping quietly.

@ Ivan, I think he was talking about the lamps as signal level indicators so perhaps low enough wattage lamps to not be a dangerous load.

@ Bob (hi) yes slew limit is not very meaningful in audio terms beyond more slew rate than we need. Power bandwidth (max frequency clean full scale sine wave) is slightly less silly, but still overstating requirements, as few applications require full scale power at 20kHz.

Go back to sleep little doggie, nothing to see here..

JR
 
Re: Damping Factor - Actual listening tests?

Scott Helmke said:
Maybe they used some kind of neon lamp?
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Not to feed the veer but neon lamps require series resistance to limit current.

An incandescent lamp is self current limiting as the lighting element heats up the resistance increases. When the gas inside a neon lamp breaks down it becomes a low impedance so requires a ballast resistance. (Typical neon lamp probes have the resistance built into the leads).

JR
 
Re: Damping Factor - Actual listening tests?

John Roberts said:
Not to feed the veer but neon lamps require series resistance to limit current.

An incandescent lamp is self current limiting as the lighting element heats up the resistance increases. When the gas inside a neon lamp breaks down it becomes a low impedance so requires a ballast resistance. (Typical neon lamp probes have the resistance built into the leads).

JR
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Not to mention that the typical neon lamp would not start to glow until about 60V or so. I don't remember exactly.

Most of the amps "back in the day" would not swing 60V. But of course it depends on what was considered "back in the day" and different days had different power/voltage capabilities.
 
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