Latest Thread Images

Featured Sponsor Listings

So, the Objective2 headphone amp - designed entirely around the measurements? (PLEASE READ RULES BEFORE POSTING)

Aug 23, 2011 at 2:43 PM Post #511 of 1,042


Since when is 2.5 Volts input with low distortion considered "a weak source"?  The designer is protecting the O2 from up to 4V of input.  How does that not seem rational?  What are you expecting to be inputed into your amps?  Consumer nominal is 200-2000mV max, and anything with a 2V output lets you attenuate it.  Usually it's only in the 200-500mV range.  Pro Nominal is usually 1-1.3V.  I have never seen any portable player that could come anywhere close to 4V, in fact most can't even REACH pro nominal levels, let alone 2V. 
 
Even on battery power at either gain setting, this amp's design appears to measure as well or better than most the stuff out there.
Quote:
amb said:
No, I am not interested in discussing this directly with the designer.  If he is the brilliant engineer that he makes himself out to be, then he must know these limitations.  Must use a weak source, must use low gain, must use AC power... too many ifs, ands and buts.  None of the amps that he lists as "competition" have these problems.
Click to expand...



 
 
Aug 23, 2011 at 2:49 PM Post #513 of 1,042
The original gain was 3.1X which was a problem for unusual sources. It has been changed. This was the only legit criticism in a thread full of BS as far as I can tell, and the problem was blown out of proportion. 
 
Aug 23, 2011 at 3:06 PM Post #515 of 1,042

And you should be sending test waveforms into your gear and checking its output to check clipping, anyway.  That's a very basic thing to do, simple, and immediately tells you how hot to make the input.  For all the dissing of Rightmark on here, it's very easy to use the scope on it.
 
Quote:
odigg said:
That makes sense.  Thanks.  I think most every portable device I use outputs less than 1Vrms, so I guess I don't have to worry too much.
Click to expand...



And ALL measuring equipment works best when you use them on the same pieces of gear and then compare the gear with the results from that measuring equipment.  Doesn't matter whether it's an expensive standalone analyzer or the input of a Sound Blaster.
 
 
Aug 23, 2011 at 3:13 PM Post #516 of 1,042

It's pretty easy to see when distortion begins on any simple waveform on a scope when passed through any preamp/mixer/headphone-amp, real or virtual, then just back the volume down on the source whatever amount you're comfortable with.  Considering none of this would happen unless you went over normal volume levels for normal gear, even the hottest gear's output as it distorts could be backed off by 50% and still be sending a very hot signal (around pro nominal) that by any measure should be getting the most out of the equipment.  Unless it's some wonky design that only has good performance at 3V, or something.  Then you should probably complain to the designer.
 
Quote:
odigg said:
You could measure the output voltage.  All you need to do is play a 1khz tone file through Foobar at full volume and measure the output voltage of the DAC.  You also need to make sure it's not clipping - I'll let somebody else tell you how to do that as I don't want to give you the wrong information.
 
 
 
Click to expand...



 
 
Aug 23, 2011 at 3:22 PM Post #517 of 1,042
NwAvGuy actually responded to Ti's criticism elsewhere. To paraphrase his points:
1. Ti is using the wrong values for both the diode drop (this is backed up by datasheet of aforementioned diode) and the peak to peak voltage.
2. It's a straw man of an argument anyway as it seems unlikely that you would use batteries with the amp when you're using home sources - and even if you did you should be fine with reasonably charged batteries.
3. Finally, to accommodate the really marginal sources (above about 2.5V if memory serves) he has slightly lowered the default gain.
 
He also expressed amusement that Ti would rigidly declare, when both the Mini3 and his design use the same battery type, that the batteries output 8.4V, as whilst trying to defend his own designs he insisted they output considerably more.
 
So to paraphrase that, the maths is wrong, the argument is wrong and Ti appears slightly contradictory to the uneducated observer.
 
Aug 23, 2011 at 3:36 PM Post #518 of 1,042

[size=10pt]Interesting, but if a given amp tests much better on the same measuring equipment (whether by your sound card input or stand alone pro test gear) than several other amps, regardless of what other unknowns are unaccounted for, isn't it likely that the knowns that have been measured indicate the much-better-testing amp will sound more accurate & transparent to the original signal? And if the measuring metrics used are numerous, rather than, say, just one (like S/N ratio or THD), that this probability drastically increases as the number of different measurements and the multiplicity of better measurements increases?[/size]
 
[size=10pt]I would certainly agree it's possible for two pieces of gear that measure reasonably similarly (and we can argue about how similar that has to be) can sound different.  But the more measurements you add or the greater the resolution used in the tests, the less likely this is to be the case.[/size]
 
Quote:
beefy said:
 

I can't believe that I agree with kwkarth on something.
 
For reference, I am a scientist and skeptical of many audiophool traditions...... but I strongly believe that anyone who thinks an amp is perfectly transparent because of a select and limited group of measurements is wrong. It shows a substantial amount of arrogance, and a strong underestimation (or misunderstanding) of the complexities of both the electronics and the human brain.
 
The amp needs to be ABX'ed, double blinded, some sort of proper listening test. Until then, both the objectivists and the subjectivists are full of it.
 
*
 
The gain issue is still not solved adequately to my mind. I cannot fathom why the designer is introducing such significant potential problems for the sake of a few dB of SNR. We all know how many noobs are going to end up with one of these, switch to a MOAR BETTAR GAINZ and wonder why it sounds bad. Seriously, even if the SNR was dropped by 30dB by moving the pot, it would still measure very well, and the problem is gone.
Click to expand...



 
 
Aug 23, 2011 at 3:59 PM Post #519 of 1,042

Which of this gear DOESN'T have a volume control on that output, though?
 
Quote:
shike said:
That could be a legitimate concern for those planning on using it with pro gear.  Do you have some specific examples handy?
 
@The Monkey
 
Would never have expected Parasound to be pushing 3v, that's crazy.
 
 
At this point maybe the gain structure should be:
 
1x - unity
2x - normal
3x - "high"
 
That would eliminate just about the entire problem.  If your source is doing 4v unbalanced then it just can't be used period.  This would allow portable sources that have 1v out to go up to 3v, and almost any home source could get around 6v without an issue.
 
Click to expand...



 
 
Aug 23, 2011 at 4:00 PM Post #520 of 1,042
 
Quote:
reticuli2 said:
[size=10pt]Interesting, but if a given amp tests much better on the same measuring equipment (whether by your sound card input or stand alone pro test gear) than several other amps, regardless of what other unknowns are unaccounted for, isn't it likely that the knowns that have been measured indicate the much-better-testing amp will sound more accurate & transparent to the original signal?[/size]
Click to expand...

 
That assumes that more accurate, better testing, and truthful to the original signal actually sounds better to the end user - and thus makes it a better amp. It is an interesting problem that I can't be arsed to solve.
 
 
Quote:
reticuli2 said:
[size=10pt]And if the measuring metrics used are numerous, rather than, say, just one (like S/N ratio or THD), that this probability drastically increases as the number of different measurements and the multiplicity of better measurements increases?[/size]
Click to expand...

 
To the pure objectivist, yes, that should be the case. But as a skeptic - of both pure the pure objectivist and subjectivist positions - I still don't think that measurements will ever be able to cover every audible performance aspect. You can't listen to measurements any more than you should listen to a boutique power cable.
 
*
 
One last thing....... PLEASE, FOR THE LOVE OF GOD, USE MULTIQUOTE.
 
Aug 23, 2011 at 4:06 PM Post #521 of 1,042
He has a point. Digging up old posts and posting over and over again isn't very helpful. You've missed the fireworks. 
wink.gif

 
Aug 23, 2011 at 4:10 PM Post #522 of 1,042


Some serious pro gear have specific main outputs that are capable of going very hot, that are capable of but not normally intended to run at, say 8Vrms before they might start clipping.  You don't run a mixing board that has a non-record "amp" out at 7Vrms just because it can theoretically handle 8.  Everyone with any familiarity with the stuff would know you wouldn't expect much of anything to be capable of using that hot a signal, except certain amps that... yes... have a volume pot before the gain stage.  And if you really need to crank your main board that hot, then your amp is way way too weak for the application.  In that case, you either get a bigger amp or more sensitive speakers.  Point of fact, those sorts of "amp" outs from mixing boards are meant to feed into mono pro amps that don't have volume pots and will have their own volume control anyway on the board.  And I suspect most of the gear being cited is exactly like that.  Name one pro device that goes over 2.5Vrms for its nominal output that doesn't have a volume control on that output.  If you find one, you'll probably want to shoot an email to the maker and ask them why (as one person liked to say in this thread) they did such a 'tarded thing.
Quote:
c61746961 said:
[citation needed]
 
Click to expand...



 
 
Aug 23, 2011 at 4:11 PM Post #523 of 1,042
[size=10pt]Oh, I don't think measurements will ever be able to totally describe what we hear either, but I think what I posted there still stands.[/size]
[size=10pt]Funny you should mention cables. In blind tests run by Thiel once at CES, I was the only one in the audience who could repeatedly call them out when they tried to trick us by swapping or not swapping the cables. But those were very special, electrically-charged-dialectic cables. And like as big as a fire-hose and had their own power supplies. Not for resale. I do like Teflon dielectrics, though... and short cables. [/size]
[size=10pt]hah hah... first, how do I see the entire thread in one long scrollable page? That would make multi-quote possible for me.[/size]
 
You must log in or register to reply here.

Users who are viewing this thread

Total: 2 (members: 0, guests: 2)
Back
Top