[zilch0md]

Hi tnmike1,
Quote:

I'm using an inexpensive Radio Shack wall-wart unit that has adjustable voltages,up to 12v.  I notice a huge volume difference at 12v.  With the Denon 5000 and UM3X IEM, Idon't need to turn the volume up at all; it's already loud enough at the minimum setting.  Under 9v power, the volume needs tobe adjusted.  Don't know about sonic differences as i'm stll in the break-in period and sound is still "maturing"  But the volume differences between 9v and 12v are amazing

I realize that it's subjective, but I don't observe a "huge" difference in volume, when switching between an 8.4-Volt internal battery and a 15.0-Volt external battery.  Can you check and see if you've got your Stepdance set to the Low Current position.  It's the switch that's by itself (not the two Gain switches).   
 
I'm thinking you might have it set for Low Current and when you plug in an external power source, the volume is going up, at least in part, because the Stepdance will automatically switch to the High Current setting whenever you attach an external power source. 
 
Thanks,
 
Mike

 

 

[Girls Generation]

Hmmm, I guess two's enough and then if I'm going on a long road trip I can just buy disposable ones hehe

 

[G3n0c|d3]

about the power consumptions, i use the alcheapo china 9v batts and it gives me 5-6 hours of pleasure and the sound is cleaner than the rechargeble ones....
 
anyways... it only cost me around 1.50 bucks for 2 9v batts....
eventhou im tempted to mod the batts but i guess im still good and still holding on lol...

 

[tnmike1]

Quote:

Hi tnmike1,

I realize that it's subjective, but I don't observe a "huge" difference in volume, when switching between an 8.4-Volt internal battery and a 15.0-Volt external battery.  Can you check and see if you've got your Stepdance set to the Low Current position.  It's the switch that's by itself (not the two Gain switches).   
 
I'm thinking you might have it set for Low Current and when you plug in an external power source, the volume is going up, at least in part, because the Stepdance will automatically switch to the High Current setting whenever you attach an external power source. 
 
Thanks,
 
Mike

 

it is, in fact, set to Low Current consumption.  OK, will switch to High Current and see what happens to the sound and if there are radical changes.  I thoughtLow Current preserved the battery life a bit
 
OK now this morning  (9:45 a.m.)  switched to High Current consumption and still notice a slight increase in volume.  Nothing radical, but can now keep Stepdance on lowest volume setting and have a reasonable sound level while doing work or research on computer.  For pure listening would increase volume.
 
Still, there is a slight difference between 9v battery and the 12v wall-wart

 

[Szadzik]

Yesterday I bought an iBasso D6 and will be testing it against the Stepdance. It seems to provide a lot of power and the size/ additional DAC seem to be interesting too.
 
What is a problem for me in the Stepdance are the dimensions and the volume knob that is very difficult to operate when I have the amp attached to my X Walkman.

 

[zilch0md]

 
Here's why the Stepdance sounds better when we increase the voltage of the battery or PSU


[size=10pt]In my quest to understand why the Stepdance SQ improves with an increase in operating voltage, I sent an e-mail to Jan Meier, which led to his referencing this datasheet on the opamp used in the Stepdance – a Texas Instruments OPA1611.[/size]
[size=10pt] [/size]
[size=10pt]Let me say up front that I’ve had no assistance from Dr. Meier with interpreting this datasheet, so please take everything I’m about to share with a grain of salt, or a cup of tea, if you prefer.  [/size]

[size=10pt] [/size]
[size=10pt]Given my assumptions and interpretations, some of which may be incorrect, the Stepdance, by nature of its opamp, appears to be a constant-voltage design, where the power delivered to the headphones (in Watts), varies not in terms of voltage, but with changes in supplied current.   [/size]
[size=10pt] [/size]
[size=10pt]Again, as I am a novice at this topic, please consider this to be “for entertainment purposes only,” but I’ll go further to say that it seems that as one advances the volume control and/or as the input voltage (inherent to the audio signal) increases, the output current (mA) supplied to the headphones increases, while the output voltage (Vpp) to the headphones remains nearly constant across all audible frequencies and beyond – right out to 105kHz – for any given supply voltage (Vs) - the voltage fed to power the opamp itself, not the voltage we supply to the Stepdance with a battery or PSU.   It’s a so-called constant-voltage design:  The amplifier produces a constant voltage across the output terminals.[/size]
[size=10pt] [/size]
[size=10pt]See Figures 4 and 27, of the OPA1611 datasheet.[/size]
 
[size=10pt]I found this information to be interesting but of no real value in terms of anything I can do to improve SQ, until I realized from looking at Figures 4 and 27 that as we increase the supply voltage (Vs), we are simultaneously increasing the otherwise constant output voltage (Vpp) (to the headphones), and thus, the output power (Watts).   And that, if my interpretations and assumptions are correct, is why the Stepdance sounds better when the supply voltage is increased!   [/size]
 
[size=10pt]An increase in supply voltage (Vs) = an increase in the constant output voltage fed to the headphones (Vpp) = an increase in power (Watts) at any given instant in time, with the variables of input signal and volume control determining how much output current (mA) we will have.  [/size]
 
If you're not seeing it, note that in Figure 4, a supply voltage (Vs) of [size=10pt]±[/size]2.25V gives us a maximum output voltage (Vpp) to the headphones of about 3.0-Volts, but with a supply voltage (Vs) of [size=10pt]±[/size]15V, the opamp produces a maximum output voltage (Vpp) of about 28.5-Volts. So, the output voltage to the headphones is constant for any given supply voltage, BUT if we increase the supply voltage, the output voltage to the headphones will also be increased.
[size=10pt] [/size]
[size=10pt]The product of voltage and current is Watts (more or less), and thus, increasing the supply voltage (Vs) translates to an increase in Watts – which translates to more headroom and better dynamics!  That’s what we’re hearing when we increase the supply voltage – more Watts!    Check out the comments made near the end of the 2-minute video seen at the bottom of this page. [/size]
[size=10pt] [/size]
[size=10pt]Going deeper and just to make things more confusing, when the datasheet references a supply voltage of [/size][size=10pt]±[/size][size=10pt]15V, in Figure 4, for example, it means 30V, the way we common folk normally refer to voltage.  Evidence of this can be seen in Figure 25, where the minimum and maximum supply voltages (along the x-axis of the chart) are shown to be 4.5V and 36V, despite the spec given near the top and elsewhere that states an allowable supply range of  [/size][size=10pt]±[/size][size=10pt]2.25V to [/size][size=10pt]±[/size][size=10pt]18V[/size][size=10pt].[/size]
[size=10pt] [/size]
[size=10pt]It’s important to understand that the supply voltage (Vs) referenced in the datasheet is NOT the voltage you or I supply to Stepdance with our choice of battery or PSU.  It’s the voltage that powers the opamp itself.  We don’t actually know what the supply voltage (Vs) to the opamp is for any given voltage we provide to the Stepdance.   I’ve read elsewhere that amplifiers use a circuit that “splits” the voltage coming in, allocating it to various tasks, the most important of which is powering the OPA1611, in the case of the Stepdance.  I’m not willing to ask Dr. Meier what percentage of the power supply voltage is actually routed to the opamp, as I would consider that to be proprietary information, but it’s safe to assume that the opamp doesn’t get 100% of it.  [/size]
[size=10pt] [/size]
[size=10pt]Thus, there’s no point in trying to use the information in the datasheet to estimate even the peak Watts supplied to the headphones by a Stepdance, much less Watts RMS, because we have no idea what the supply voltage (Vs) to the opamp is for any given battery or PSU voltage that we give the Stepdance.[/size]
[size=10pt] [/size]
[size=10pt]And that really doesn’t matter to me as much as the knowledge that we actually do get more Watts output to the headphones when we increase the voltage of our battery or PSU (up to the maximum of 15VDC, per Dr. Meier’s specs.)[/size]
 
Mike
 

 

[ianmedium]

Mike,
You must be a teacher or such as I am not at all technically minded but was able to follow what you said and it makes so much sense, thank you again for taking the time to do all of this especially for those of us who would not have a clue where to start!

Looks like my battery pack will be with me late Friday.. I can't wait.. I may have one other improvement coming soon as well, more of which later!!

 

[zilch0md]

 
ianmedium,
 
Your hunch regarding my occupation is pretty close - I'm actually a software quality assurance engineer for a Japanese company you would recognize, but easily 30% of my time is not spent testing new releases of software, but rather teaching classes in our training center to field engineers who do installations at our customer sites -and- authoring CBTs (computer-based-training) that cover the same subject matter.   I also generate a lot of the raw text that gets formatted into the official documentation produced by our technical writers. 
 
So yes, I love to teach and I love to write. 

 
I can't wait to hear what you have in store for us (regarding your cliffhanger...)
 
Thanks,
 
Mike
 
 
 
 
 
 

 

[Girls Generation]

yay for 8.4v ipower batteries? In a few weeks or months, when I'm familiar with the amp, i might try the stuff you did D

 

[zilch0md]

 
Girls Generation,
 
Have you received your Stepdance yet?
 
I think you will want to use the 8.4-Volt internal batteries on ocaision, even if after you get a larger external battery pack like the Energizer XP8000.  The 8.4-Volt internal batteries are a lot lighter when you want to keep the weight down for portability and the SQ is still excellent.
 
I'm looking forward to your report of the Stepdance with the Audio Technica W1000X.
 
Thanks,
 
Mike

 

[Girls Generation]

Would there be a noticeable difference between using the 8.4v and the xp8000? ._.;; I don't really care about weight and size. I have a shoulderbag with me but if there's not really a big difference between the 8.4v and the xp8000, i'd rather carry the lightweight one. 
 
I might sell my fullsize rig to get the JH3A combo. Someone said it blows away fullsized desktop rigs with a $3000 setup...

 

[ianmedium]

Mike, that explains it, your students are lucky to have you.
I will fill you in on the cliffhanger as soon as I can confirm it, hopefully this Friday!
 
GG, you are more than welcome to try my XP when I get it with your stepdance to see the differences. I am like you and carry a bag with me at all times so the extra weight and bulk is of little consequence to me. I am looking forward to it getting here!

 

[Szadzik]

Quote:

Would there be a noticeable difference between using the 8.4v and the xp8000? ._.;; I don't really care about weight and size. I have a shoulderbag with me but if there's not really a big difference between the 8.4v and the xp8000, i'd rather carry the lightweight one. 
 
I might sell my fullsize rig to get the JH3A combo. Someone said it blows away fullsized desktop rigs with a $3000 setup...

When you test one against another sitting at home and concentrating on it you will notice a difference. When you are on the go though, I doubt you will hear any difference.
 
Still, if you have not got any power source yet you will be better off getting XP8000 as it has lots of power and can charge other devices too.
 

 

[Girls Generation]

how long does the charge last? I already bought my 2 ipower batteries and the charger for them. It's arriving tmrw, but I can send it back for a refund I think...

 

[Szadzik]

 
Quote:

how long does the charge last? I already bought my 2 ipower batteries and the charger for them. It's arriving tmrw, but I can send it back for a refund I think...

They last around 10 hours.