[Iced]

By switchable I mean switchable voltage out starting from 3 to 12v.

 

[senny-ftw]

That doesn't reveal much...

See if you can find a model number / manufacturer and do a google search. If it's regulated, the product description would say so.

 

[cooperpwc]

Quote:

Originally Posted by jamato8 /img/forum/go_quote.gif I wish someone would come out with one that also had an optical in as it is so easy to implement and works great with portable CD players that have optical.

x2. Indeed.

 

[onedigit]

Quote:

Originally Posted by jamato8 /img/forum/go_quote.gif I am sure he knows and to say plenty is odd. I can understand why you would want to know what the power out is and it is not unreasonable to ask. The amp looks very interesting and it is nice to have one with a dac built in. I wish someone would come out with one that also had an optical in as it is so easy to implement and works great with portable CD players that have optical.

Before I get into trouble I’d better quote what exactly Jan said instead of paraphrasing. This statement did put me at ease but I was just looking for some anecdotal information.

Waiting is the hardest part of buying new toys. It’s like being in an upscale restaurant starving and waiting for your order to arrive, you can only watch and imagine as the entrées waft past your nose and eyes …


“Please don't worry. The MOVE is able to drive the K701 to very unhealthy levels!

Cheers

Jan”

 

[itsborken]

Pardon the poor quality, but here's the move next to a porta corda mkIII usb

The Move has a USB cable attached to the back, whereas the mkiii usb has the usb connection in the front.

 

[itsborken]

Quote:

Originally Posted by Iced /img/forum/go_quote.gif I have a switchable adapter hanging around but I don't know if its regulated or not. Are all the adapters with switchable output regulated? The answer may help people who are in search of an adapter for their corda moves.

Somebody previously noted that their 'switchable' (and non switchable) power supplies were putting out over 13vdc. That would be non-regulated behavior for a 12vdc PS.

The way you are using 'switchable' is not how power supplies are normally described (adjustable might be better). From Wikipedia...

Power supplies are generally linear or switch-mode. Linear power supplies use linear regulators which vary output via diodes (constant output), where as switch-mode PS incorporates a switching regulator — an internal control circuit that switches power transistors (such as MOSFETs) rapidly on and off in order to stabilize the output voltage or current. Switching regulators are used as replacements for the linear regulators when higher efficiency, smaller size or lighter weight are required. They are, however,more complicated and their switching currents can cause noise problems if not carefully suppressed.

Since adding noise to a circuit runs counter to what we want for audiophile applications, we favor a linear power supply over a switch-mode power supply.

Power supplies are also lsted as regulated or non-regulated: The regulation of power supplies is done by incorporating circuitry to tightly control the output voltage and/or current of the power supply to a specific value. The specific value is closely maintained despite variations in the load presented to the power supply's output, or any reasonable voltage variation at the power supply's input. This kind of regulation is commonly categorised as a Stabilized power supply.

So, we would want to pick a Regulated power supply as Jan says there is not a lot of extra tolerance built into the circuit if the power supply is sloppy with its output. Also, I believe Jan has a circuit to double the voltage, so that cuts down on the efffective tolerance too.

For the Move, try to get a Linear Regulated power supply for $15 and forget about the nagging feeling you'll have about burning up your Move. If it doesn't say Regulated or Stabilized in its description, it probably isn't so keep looking...

 

[Iced]

Thank you for your reply.

 

[itsborken]

Quote:

Originally Posted by Iced /img/forum/go_quote.gif Thank you for your reply.

np, wikipedia did the heavy lifting.

 

[ElDanno]

Quote:

Originally Posted by onedigit /img/forum/go_quote.gif If anyone has listened to the 701’s with the Move I would like t hear your thoughts.

It can drive them very loud and sound very good to these ears. They are quite loud at 11 o'clock on the volume pot. Mine is using the default high-gain, high-current config.

 

[koto-in]

Quote:

Originally Posted by ElDanno /img/forum/go_quote.gif It can drive them very loud and sound very good to these ears. They are quite loud at 11 o'clock on the volume pot. Mine is using the default high-gain, high-current config.

With the low impedance of the K701's, you could try a low-gain, high-current configuration to see if it sounds better.

 

[koto-in]

Quote:

Originally Posted by onedigit /img/forum/go_quote.gif Does anyone know the output power of the Move?

The specs say that the amp provides "maximum" amplification of +4dB in low gain mode and +17dB in high gain mode. It is not clear under what conditions this maximum applies; whether it is the absolute maximum capability of the amp, the maximum available amplification under the default battery configuration, or if it is the minimum maximum achievable under the most current-limited conditions. Power output figures are only meaningful when these conditions are specified.

However, let's assume that the amp can provide +17dB to the AKG K701's. They have a sensitivity of 105dB SPL/mW and with a +17db increase in amplification, you could theoretically achieve 122dB. Quite unhealthy indeed; this is above the threshold of pain! Considering that Jan's non-portable amps are typically specified as providing a maximum amplification of +10dB, it would appear that available power in this case is probably not the decisive factor. One can rather be focused on sound quality as well of course on issues of size, battery-life, features, etc. as appropriate to a portable amplifier.

 

[Honus]

Does anyone know when Jan will be offering the "Move" without DAC - Hopefully at a lower price point?

 

[jcx]

Looks like you don’t have the power/sensitivity/gain thing quite right there, +4 and +17 dB gain refers to how much the input V is amplified by ( ~ 1.6x and 7x )
the max output spl is determined by source V (desktop cdp 2 Vrms, iPod 1 Vrms typ, some AAA pwr daps may be 0.5 Vrms or even less) times gain setting and headphone Ohms&Sensitivity and the power supply V option and output limitations of the amp

The Move does complicate things a little with the power options
It appears from the Mier site and comments here that Jan is using a switchable splitter/doubler power supply circuit internally

This means the amp can be running from +/- 2.5 V to +/-12 V internal supplies depending on the “current” setting and power source

The AD8610 op amp is used, and I assume without a output buffer which Jan specifically mentions when used in his other products and does not claim in the Move description/specs

We can work from the AD8610 data sheet and the Move specs to get an idea of the Move capabilities

The AD8610 data sheet specs Iout as +/30 mA +/-5 V supplies, +/-45 mA +/-13V supplies, with the minimum supply V speced at +/-5 V

A few other limitations can be gleaned from the data sheet:

the Iq vs Vsupply plot suggests that the AD8610 actually biases up at ~ +/- 3.5 V supply – but the supply current is changing too steeply around +/-2.5 V for me to think the AD8610 would operate well at the low current setting of the Move operating from USB power

another helpful plot is the dropout V vs load current plot, with the AD8610 output dropping 1 V at 10 mA , >3 V at 100 mA load with +/-13 V supplies

now the datasheet numbers can be compared against headphone load/sensitivity numbers, I believe the AKG K701 is a popular “difficult” load, requiring more current than Grados for the same spl at higher V too:

Quote:

Originally Posted by jcx /img/forum/go_quote.gif how about anyone else here doing some numbers when this sort of question arises? K701 62 Ohms, 105 dB/V I consider being able to reach 120 dB SPL before clipping the amp to be "adequate" this gives 5.6 Vrms, 90 mArms which needs another factor of 1.414 for peak values 128 mApk is a lot of current for a headphone, +/- 8Vpk isn't coming from a single 9V powered "CMOY" SS - only recent surface mount op amp will do this alone, look for AD8397 or TPA6120 buffered op amp types with BFU634 or the HA series monolithics and most discrete buffer or all discrete ss amps should be able to do this with enough supply V (some single ended Class A discrete ss designs may not be biased heavily enough though ) Tubes are rather more hard pressed, transformers could do this if sized appropriatly but decent transformers add ~ $100 to the parts cost so you won't be seeing them in sub $500 amps OTL tube amps would need to be biased at > 250mA and most would require parallel output tubes to reach this current level (there are a very few "monster" tubes like 6S33S which could do the job in singles) you could get by with an amp not able to cleanly drive the K701 to to 120 dB if your musical taste runs to todays low dynamic range over-compressed crap

the Move’s “high current” doubled supply V helps but the AD8610 output current capability isn’t up to the task of driving K701 to 120 dB spl

the +/-45 mA spec gives ~30 mArms
30 mArms * 62 Ohms = 1.86Vrms
20 * log10(1.86) = +5.4 dB re 1V
105 dB/V + 5.4 dB = 109.4 dB max spl

from AKG K701 driven by AD8610 at datasheet speced max output current

it is possible that the Move can be a little louder with added op amp distortion short of outright clipping, but the 65 mA short circuit current spec suggests only 3 dB more spl could be expected before hard clipping (the plotted Iout vs dropout V does go to 100 mA but this cannot be relied on in production)

~110 dB spl is reasonable headroom, especially in a portable, just not enough to push into high end desktop territory when driving current hungry K701

The Move might have enough V swing to get to its current limit with the K701 when used with a 9.6 V 8 cell battery in “low current” mode, but certainly with any 9V battery in ”high current” mode


for Senn Hd600/650 the story is somewhat better, in this case the supply V minus the 1-2 V dropout limits the power into the 300 Ohm cans

with external 12 V supply and “high current” mode the Move/AD8610 should swing +/-10 V (= 7 Vrms) into 300 Ohms

(7^2) / 300 = 163 mWrms
10 * log10(163mW/1mW) = +22 dB re 1 mW

98 dB/mW + 22 = 120 dB spl

from HD600/650 driven with Move in “high current” mode, 12 V external supply

with battery power “high current” mode is the only real option with 300 Ohms cans and max battery Voltage will directly impact headroom, I would guess –2 to –4 dB vs the 120 dB spl with 9.6 or 8.4 V “9V” batteries vs 12 V external supply


I'm sure someone will object to 120 dB as a goal for heaphone peak spl but you really should read up on Dynamic Headroom:
Quote:

Originally Posted by jcx /img/forum/go_quote.gif actually I'm not using dangerous listening levels - really carefully read the Headwize "Preventing Hearing Damage When Listening With Headphones" article http://headwize.com/articles/hearing_art.htm the average level I was using as an example was ~ 90 dB - perhaps I should have said "more than comfortably loud" - but way less than live club levels and quite safe at the hour or so I might devote to a critical listening session - not as background music the +100 dB peaks were <10% of the set’s running time as the brass punched out the theme, the percussion must have been pushing the instantaneous peaks ( for only milliseconds ) 10dB higher the OSHA exposure limits allow 90 dB for 8 hr/day, 2 hr for 100 dB Osha isn't the final word on hearing safety but I'm staying at least 4x below their daily exposure time limit for any level - and not freeing up the time for a critical listening session every day... ..."The numbers" can't tell you what will sound good but the very basics of how loud can this amplifier get with this headphone without clipping (and how loud it needs to get to reproduce music) shouldn't be dismissed/ignored if you really want to get serious about the more subtle issues everyone here seems to feel so important

 

[ManAtWork]

Quote:

Originally Posted by Honus /img/forum/go_quote.gif Does anyone know when Jan will be offering the "Move" without DAC - Hopefully at a lower price point?

What I heard from Jan, there is a smaller portable amp without USB DAC and will be released about several months later. However, you still can consider the Porta Corda with cheaper price.

 

[ogewo]

itsborken: thank you for those PCIII + Move pictures. Any chance at getting a few more?

Also, would you be able to compare the USB DAC functionality and quality between the two.