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JDS Labs C5 portable amplifier appreciation + discussion thread (check 1st post for review) - Page 16

post #226 of 1009
2/18/13 at 3:39am
The red one is sooo sexyyy tongue_smile.gif

http://www.jdslabs.com/images/70/Red/1600/Red-Iso.png
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post #227 of 1009
2/18/13 at 5:07am
Quote:
Originally Posted by randomkid View Post

updated first post with specs and details.

also im probs getting it in red smily_headphones1.gif

will do a comparison against C421 AD8620


cant wait for that too biggrin.gif
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post #228 of 1009
2/18/13 at 9:08pm

Hopefully this is a valid question here , in comparison between the C5 and the Objective 2 . What would be the difference between sound quality .

 

P/S I know it is not out yet .

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post #229 of 1009
2/18/13 at 9:13pm
Quote:
Originally Posted by grandmike View Post

Hopefully this is a valid question here , in comparison between the C5 and the Objective 2 . What would be the difference between sound quality .

 

P/S I know it is not out yet .

In the future, I'm sure there will be a ton of comparisons between the C5 and the O2 as many of the people in this thread have an O2, but John of JDS Labs said in the C5 blog comments:

Quote:
Yes, C5 should be audibly indistinguishable from other neutral amplifiers such as O2.

 

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post #230 of 1009
2/18/13 at 9:17pm
Quote:
Originally Posted by grandmike View Post
...

P/S I know it is not out yet .

 

So you want someone to guess the answer? wink.gif

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post #231 of 1009
2/18/13 at 11:04pm
Quote:
Originally Posted by ClieOS View Post

 

So you want someone to guess the answer? wink.gif

 

One of the best option would be looking at the specs .

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post #232 of 1009
2/19/13 at 12:14am
Quote:
Originally Posted by grandmike View Post

One of the best option would be looking at the specs .

 

You can tell SQ of an amp (or an audio gears) by spec only when it really sucks, and that's assume there is a manufacturer willing to post a very bad looking spec. Most of the time spec doesn't tell you much at all, and big number are often threw around just for marketing to those who are less informed. Of course, I don't think John is throwing number here but when you have two amps that is beyond the limitation of most human hearing on spec, you need to actually listen to both to decide when is better to your ears.

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post #233 of 1009
2/19/13 at 12:22am
Quote:
Originally Posted by ClieOS View Post

Quote:
Originally Posted by grandmike View Post

One of the best option would be looking at the specs .

 

You can tell SQ of an amp (or an audio gears) by spec only when it really sucks, and that's assume there is a manufacturer willing to post a very bad looking spec. Most of the time spec doesn't tell you much at all, and big number are often threw around just for marketing to those who are less informed. Of course, I don't think John is throwing number here but when you have two amps that is beyond the limitation of most human hearing on spec, you need to actually listen to both to decide when is better to your ears.

I think that's where objectivists get so tied-up with things, and I agree with you on that point. I read through some of your < $200 amp comparisons in your signature and from the looks of it, you could distinguish a difference between the two different version of the C421. Of course I haven't seen any measurements between the two op-amps, but I think they would be pretty similar. Also, some [insert sound science term only] tests would probably have to be done to make sure you could reliably hear a difference between them, if you're going the objectivist path.

 

Speaking of measurements though, is there any way to extrapolate the Vrms values to a more reasonable 32 Ω value? I know John mentioned in the C5 blog post comments that they're trying to find a solution to this, but for the time being can it be extrapolated from the 150 and 600 Ω values?

Extrapolated Values (Click to show)

Assuming linear behavior:

Math (Click to show)

 

(600 Ω - 150 Ω) / (P_h - P_m) = (150 Ω - 32 Ω) / (P_m - P_s)

 

where

P_h = [(Vrms600)^2] / R600 = [(4.146 V)^2] / 600 Ω = 0.02865 W or 28.65 mW

P_m = [(Vrms150)^2] / R150 = [(3.337 V)^2] / 150 Ω = 0.07424 W or 74.24 mW

 

Solving for P_s yields: 0.08619 W or ~86 mW @ 32 Ω

 

This sounds like a reasonable amount of power for a portable amplifier.

 

Using a similar extrapolation for 41 Ω yields ~84 mW, which should be all right for an HE-500 assuming the measurements from InnerFidelity are accurate (2.04 mW needed to reach 90 dB SPL).

Math (Click to show)

 

SPL_max = 10 * log(P_max / P_90SPL) + 90

 

where

P_max is the maximum power the amp can provide at a given resistance; in this case 84 mW @ 41Ω

P_90SPL is the power needed to reach 90 SPL; in this case 2.04 mW according to InnerFidelity

 

Solving for SPL_max yields: ~106 dB, which is quite loud (for me at least)

According to Etymotic, ~105 dB is the volume level one would experience in a loud sporting event or a concert band

 


Edited by miceblue - 2/19/13 at 1:28am
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post #234 of 1009
2/19/13 at 12:42am
Thread Starter 
I will compare it to O2 and C421 for reference purposes, as people seem to be asking for that
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post #235 of 1009
2/19/13 at 7:45am
Quote:
Originally Posted by ClieOS View Post

but when you have two amps that is beyond the limitation of most human hearing on spec, you need to actually listen to both to decide when is better to your ears.

 

And, similarly, when an amp's noise and distortion specs are beyond the limitation of all human hearing, no listening test is required.

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post #236 of 1009
2/19/13 at 10:35am
I think you should add real measured amp's noise and distortion specs instead of claimed specs than a listening test is not required.

Anyway don't forget that humans do not only have hearing alone.We can feel,see,smell,touch, etc.You may not be able to hear a 10hz sound but you can feel it provided the gear you have can reproduce it.And with all the other sensory input the brain does effect your perception and frankly in real life we don't listen blind unless of course you are blind smily_headphones1.gif.
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post #237 of 1009
2/19/13 at 10:42am
Quote:
Originally Posted by rckyosho View Post

I think you should add real measured amp's noise and distortion specs instead of claimed specs than a listening test is not required.

Anyway don't forget that humans do not only have hearing alone.We can feel,see,smell,touch, etc.You may not be able to hear a 10hz sound but you can feel it provided the gear you have can reproduce it.And with all the other sensory input the brain does effect your perception and frankly in real life we don't listen blind unless of course you are blind smily_headphones1.gif.

If you were referring to the C5 in your first sentence, John posted the amp's real measurements on the C5 blog entry.

http://blog.jdslabs.com/?p=464

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post #238 of 1009
2/19/13 at 11:23am
Thread Starter 
I posted all specs on first page, and link to blog
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post #239 of 1009
2/19/13 at 1:05pm
Quote:
Originally Posted by HamilcarBarca View Post

 

And, similarly, when an amp's noise and distortion specs are beyond the limitation of all human hearing, no listening test is required.

Because you're so absolutely sure that they've measured every type of dynamic distortion that can occur in music and into every load?rolleyes.gif

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post #240 of 1009
2/19/13 at 7:26pm

Not all measurement are measured equally, so to speak.

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