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burson new soloist headphone amp - Page 47

post #691 of 1162

Impossible to know without a scope.  All we can say is the higher the gain, the lower the feedback.  Can also say this... unless you have a weak source you will clip long before you out of sweep on medium gain.  Low gain in my case with the LCD-2.

post #692 of 1162
Quote:
Originally Posted by Solude View Post

Impossible to know without a scope.  All we can say is the higher the gain, the lower the feedback.  Can also say this... unless you have a weak source you will clip long before you out of sweep on medium gain.  Low gain in my case with the LCD-2.

 

I hear you.  

 

As a rule, I like to use the lowest gain that delivers sufficient SPL, to lower the noise floor, if nothing else, and in the case of an amp with a stepped attenuator, to reduce the dB size of each step, for greater finesse in controlling the volume, but if I'm not hearing any difference in noise floor with a particular headphone, I like to ask the amp's designer the question I've asked Burson, on the reasonable assumption that they are more familiar with the amp's design than I am and the possibility that a given design might offer more headroom when the volume is turned down with high gain, than when the volume is turned up with low gain.

 

That's about the longest sentence I've ever written.  redface.gif

 

Thanks,

 

Mike

 

(Listening to The Way I Am, from Ingrid Michaelson's Girls and Boys)

post #693 of 1162

Gain has no effect on the rails so the ceiling remains the same.  Think of it as input math, nothing else.  Use the gain that when multiplied by the input hits the ceiling of 8V unloaded, 6V into 30ohm.  Give or take.

post #694 of 1162

FYI Soloist owners, the people at Home theater Hi-fi measured the soloist. It seems it measures really well (for Objective guys)

http://www.hometheaterhifi.com/power-amplifiers/power-amplifiers-reviews/burson-soloist-headphone-amplifier/page-4-on-the-bench.html

 

Pulling the trigger on the Baby soloist soon ;)


Edited by thecourier - 2/9/13 at 12:52pm
post #695 of 1162

Solude,

 

I'm getting more confused by your posts than edified, but I say that while respecting the fact you obviously understand this stuff a lot better than I do.  

 

I'm confused because you first posted that my question to Burson would be impossible to answer without an oscilloscope and that you use Low gain with the Soloist and LCD-2, but now you're saying that the choice of gain has no effect on headroom.  I may be misinterpreting one position or the other out of my ignorance of the terminology, but they seem to conflict.

 

Let's clarify things with this yes/no question:  If all three combinations of gain and volume setting yield identical SPL at the headphones, will there will be any difference in available headroom?   

 

Thanks,

 

Mike

post #696 of 1162
Quote:
Originally Posted by thecourier View Post

FYI Soloist owners, the people at Home theater Hi-fi measured the soloist. It seems it measures really well (for Objective guys)

http://www.hometheaterhifi.com/power-amplifiers/power-amplifiers-reviews/burson-soloist-headphone-amplifier/page-4-on-the-bench.html

 

Pulling the trigger on the Baby soloist soon ;)

 

 

Good news, but not that surprising. It does sound excellent. I'm always impressed with this little guy.

post #697 of 1162
Quote:
Originally Posted by zilch0md View Post

If all three combinations of gain and volume setting yield identical SPL at the headphones, will there will be any difference in available headroom?   

 

 

Absolutely no difference at all.  The only difference is how quickly you hit the ceiling.  My old Peak was terrible for this.  It had 14x gain and a 7v ceiling.  Meaning a source with 500mV would cap it out and my PWD2 would ask 39V at wide open... ie run out of steam LONG before I run out of sweep.

 

And the reviewer that wrote the bench part of that review is borderline incompetent.  Max output is not limited by the gain, it's limited by the input.  The rails and bias don't change because you adjust the feedback loop.  Also, and I know Tyll does the same, but measurements at idle aren't terribly useful.  They're a good starting point to weed out the obviously flawed but don't show that the performance is maintained up to the rated output.

 

If you look at the HA-160 scope results, which though run at unity are near it's clip point, the graphs are ugly ;)  Running the scope below clipping point also unfairly rates class AB at pure class A since at the measured output... both are class A /facepalm


Edited by Solude - 2/9/13 at 4:00pm
post #698 of 1162
Quote:
Originally Posted by Solude View Post

Absolutely no difference at all.  The only difference is how quickly you hit the ceiling.  My old Peak was terrible for this.  It had 14x gain and a 7v ceiling.  Meaning a source with 500mV would cap it out and my PWD2 would ask 39V at wide open... ie run out of steam LONG before I run out of sweep.

 

[snip]

 

I must be even more ignorant than I thought.  To my understanding, your first two sentences, quoted above, seem to contradict each other.  

 

So you're saying:  "There's absolutely no difference in headroom (at low, medium, or high gain), but there is a difference in how quickly you will hit the ceiling."

 

Dissecting that with my chain-saw brain instead of the scalpel I should be using...

 

The ceiling is the same height, whether I use Hi gain or Low gain to achieve the same desired SPL, but with one of these two gains, I will "hit the ceiling" more quickly - as in sooner - as in, we run out of headroom in less time than we would if we were using the other gain.

 

Please spell it out for Mr. Dumb-dumb, here - I've read your entire post several times, but I still don't get it.  Which level of gain makes exactly what happen too quickly and why would we want that event to happen more slowly?

 

blink.gif

 

Sticking my village idiot neck out even further, I'm going to guess, in part due to your prior statement that you prefer to use low gain with the Soloist and LCD-2, that what you're saying here is that even though high and low gain yield the same exact amount of headroom, when using high gain, with a source that can drive the amp with nearly 20 times the standard 2-Volts (39V), the amp runs out of headroom more "quickly" (I still don't get this part - even guessing about the rest of it) than it does when you drive the amp with a source that puts out only one fourth as much power as the standard 2-Volts (500mV).

 

Huh?

 

blink.gif

post #699 of 1162

Gain is a voltage multiplier, not a power output.

 

So using easy numbers... 2V source, low gain is 2x, medium gain is 5x, high gain is 8x, max power is 8V

 

Max power can't change.

 

The stepped attenuator sweeps from -60dB to 0dB.  0dB being wide open.

 

So...

 

2x2v=4v

5x2v=10v, 2v beyond the ceiling

8x2v=16v, 8v beyond the ceiling

post #700 of 1162

Thanks Solude!  
 
I'm starting to put things together, now.  
 
The specs for the Soloist say that it puts out 0.18 Watts into 16 Ohms on Low gain, 1.8 Watts into 16 Ohms on Medium Gain, and 4.0 Watts into 16 Ohms on High gain.  
 
The Soloist's high and low gain differ by a factor of 22.2.
 
Your example of a low gain offering a 2x multiplier and high gain offering an 8x multiplier is only a 4x difference between high and low gain, not a 22.2x difference.
 
If I understand your explanation, correctly, applying the real ratio of the high gain multiplier to the low gain multiplier (a 22.2:1 ratio, instead of a 4:1 ratio), I'm left with more questions, unfortunately...  
 
Do we know what the max power is in Volts for the Soloist (vs. the 8 Volts given in your example)?  (If we don't know the max power in Volts, then how can we know or be concerned about which gain setting might hit the ceiling for a given source voltage?)
 
Even though we know that the multiplier for the Soloist's high gain is 22.2 times greater than the multiplier for the Soloist's low gain, do we know the actual multiplier for any of the three gain settings?   (If we don't know the actual multiplier for any of the Soloist's gain settings, then even if we know the answer to my previous question (the max power in Volts), we're still stuck with...  how do we know or be concerned about which gain setting might hit the ceiling for a given source voltage?)
 
Thanks!
 
Mike
post #701 of 1162

The numbers I gave are the real ones, ish.  The source number was the one for easy math.  8Vrms is the max output.  Where Burson got their ad press numbers, I don't know.  But the VOS specs say 7dB, 18dB and eye balling the chart is medium is 13dB.

 

But the text and chart don't match, at all.

 

Using HTHF numbers they got 2.75:5.5:9.1...

 

1.2V source 7dB=2.7V, 13dB=5.4V, 18dB=9.5V...the lower 9.1V might be from clipping hard.

 

So into the LCD range that's...

 

122mW, 486mW, 1500mW

 

Remembering that voltage is part of power, and that gain only refers to voltage.  That said, the Soloist can't do 9.5V so the 1500mW is academic.  The usable number before clipping kicks in is 500mW.  So even on a gimpy source of 1.2V... medium gain is enough to cap out.

post #702 of 1162

Just my 2 cents for Mike:

 

If it helps you:

 

1) Gain (a number of times "something") is only related to the voltage, as Solude said.  So "something" is a voltage, not anything else.

 

2) One simple formula, amongst others: Power = Voltage * Voltage / Impedance (Ohms).

 

SO, if you've got a 2x gain, the voltage is multiplied by 2.  BUT, the power is multiplied by 2 * 2 = 4.  This explains your numbers of more than 20 when dividing the power at max gain by the power at min gain.

 

Nothing subjective in what I wrote, and I never measured any of the specs of the Soloist I own, I must add.  So my contribution is purely theoretical, but not mistaken I think, or please correct me :)


Edited by CoolBurn - 2/10/13 at 5:19am
post #703 of 1162

Thanks guys - it's really sinking in, now.  biggrin.gif

 

Quote:
Originally Posted by Solude View Post

The numbers I gave are the real ones, ish.  The source number was the one for easy math.  8Vrms is the max output.  Where Burson got their ad press numbers, I don't know.  But the VOS specs say 7dB, 18dB and eye balling the chart is medium is 13dB.

 

But the text and chart don't match, at all.

 

Using HTHF numbers they got 2.75:5.5:9.1...

 

1.2V source 7dB=2.7V, 13dB=5.4V, 18dB=9.5V...the lower 9.1V might be from clipping hard.

 

So into the LCD range that's...

 

122mW, 486mW, 1500mW

 

Remembering that voltage is part of power, and that gain only refers to voltage.  That said, the Soloist can't do 9.5V so the 1500mW is academic.  The usable number before clipping kicks in is 500mW.  So even on a gimpy source of 1.2V... medium gain is enough to cap out.

 

The amazing thing about your findings Solude, is that the ratio you've given above ( 2.75 : 5.5 :  9.1 ) correlates very well with my observation that the SPL delivered to the ear pads on High gain with the attenuator at step 8, is not as high as it should be, when you consider that nearly identical SPLs can be achieved by using Medium gain + Step 10  vs.  Low gain + Step 12 - as shown in my e-mail to Burson, posted on the previous page:  

 

Quote:
Originally Posted by zilch0md View Post

I just sent the following e-mail to Burson Audio...

 

[snip]

 

Low Gain  +  Attenuator at Step 12   84.6 dB

Med Gain  +  Attenuator at Step 10   84.5 dB
Hi Gain     +  Attenuator at Step 8     84.0 dB        <----  Question:  Why isn't this 84.5 or 84.6 dB?    
 
                                                 Answer:  The ratio is 2.75 : 5.5 : 9.1,  instead of 2.75 : 5.5 :  11.0
 
                                                                                     2    :  4   : 6.6,   instead of   2   :   4  :    8

 

 

I have a cheap, handheld SPL meter in addition to the iPhone app SPL meter I used to produce those measurements.  The two SPL meters independently reveal that when I use High Gain in combination with "turning down the volume" by two steps,  I always get an SPL that's less than what I get on Medium or Low Gain (in combination with two-step compensation at the attenuator.)     Anybody with an SPL meter should be able to reproduce this very empirical indication that the Soloist's High Gain setting is "hitting a ceiling" (when using a DAC that outputs 2.0V rms, at the settings shown, with 50-Ohm headphones).

 

So, at least with my source and my headphones, the voltage multipliers are effectively  limited to 2x, 4x, and 6.6x  instead of 2x, 4x, and 8x.

 

I'm done using High Gain with a 2.0V rms source and 50-Ohm headphones - thank you!   

 

But my SPL measurements do not show evidence of Medium Gain hitting any kind of a ceiling.   

 

Is it just a coincidence that my measurements of SPL at High Gain are always less than they should be relative to Low and Medium Gain when making 2-step adjustments as shown in my e-mail to Burson?   In other words, when using a DACport LX or DACmini CX as my source, where both are rated at 2.0V rms output, into my 50-Ohm headphones, do I really have to avoid using Medium Gain, also (per your last comment, bolded, above, where you say even a 1.2V source will cause Medium Gain to hit the ceiling)?   Don't my SPL measurements show that I'm not suffering any clipping when using Medium Gain?

 

Lastly, would the use of  a 600-Ohm load (Beyerdynamic T1), allow the use of medium or high gain without hitting the ceiling with a 2.0V (or even a 1.2V) source?  

 

Quote:
Originally Posted by CoolBurn View Post

Just my 2 cents for Mike:

 

If it helps you:

 

1) Gain (a number of times "something") is only related to the voltage, as Solude said.  So "something" is a voltage, not anything else.

 

2) One simple formula, amongst others: Power = Voltage * Voltage / Impedance (Ohms).

 

SO, if you've got a 2x gain, the voltage is multiplied by 2.  BUT, the power is multiplied by 2 * 2 = 4.  This explains your numbers of more than 20 when dividing the power at max gain by the power at min gain.

 

Nothing subjective in what I wrote, and I never measured any of the specs of the Soloist I own, I must add.  So my contribution is purely theoretical, but not mistaken I think, or please correct me :)

 

Thanks for this CoolBurn - it was a missing ingredient to my understanding - power not having the same ratio as the voltage multipliers.  smile.gif  

 

Mike

 

(Listening to Do Your Thing, from Isaac Hayes' Shaft)


Edited by zilch0md - 2/10/13 at 8:55am
post #704 of 1162

You're welcome Mike.

 

In addition, I should say that when Solude is talking about "hitting the ceiling" (the max voltage output, given the rails values), it should only occur when using a certain gain value AND VOLUME value (the position of the attenuator I mean) !

 

Actually, in order to hit the so-called "ceiling", in other words the max voltage the amp is able to deliver, you have to really get this max voltage reached in your load (your headphones), so you don't hit the ceiling any faster for a given SPL using any of the 3 gain values.  But by using too big a gain value, you should be able to reach the ceiling (means clipping) only by turning the attenuator, which should be impossible if a correct gain value were chosen (avoiding clipping at all cost cause it's really the last thing you want, it's even dangerous for your headphones !)

post #705 of 1162

Definitely over thinking it Zil.  Think of gain as the multiplier needed to hit max voltage before running out of sweep on the stepped.  And think of the stepped as a divider.  Not much point in multiplying input by a large number only to divide it again to bring it back ;)

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