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Am I the first owner ??? Qualia 010 !!! - Page 23

post #331 of 645
Thanks for the update and the Pics Nik!

I should become the RP5cav by Thursday.
post #332 of 645
Quote:
Originally Posted by Iron_Dreamer
I concur wholeheartedly.
I agree too. I think the pot was used rather than the stepped attenuator to accomodate the motorized drive / remote control: Rudi's quote: "The volume control is achived by e IR remote unit, the potentiometer is moved by motor."

In theory (and in practice in my experience) there are quieter and more transparent methods of attenuation. I think this method is generally employed when remote control operation and price point objectives overide noise and transparency issues.
post #333 of 645
Quote:
Originally Posted by mbratrud
I agree too. I think the pot was used rather than the stepped attenuator to accomodate the motorized drive / remote control: Rudi's quote: "The volume control is achived by e IR remote unit, the potentiometer is moved by motor."

In theory (and in practice in my experience) there are quieter and more transparent methods of attenuation. I think this method is generally employed when remote control operation and price point objectives overide noise and transparency issues.
Makes sense that it'd be needed for the motorized remote control, but it's a shame that it makes this less than the uncompromising testbed that one would hope Nik to have in his battle of titans.
post #334 of 645
There would be absolutely no reason why the input pot can't stay
exactly where it is, and a fiberglass extention rod added so that the
knob can be on the front panel with no impact on the audio quality.
Many designers do this.
post #335 of 645
It looks like rudi took mr gilmore's comments about build quality seriously. That looks like a monster amp.
post #336 of 645
I would like to know which should be the price, for such a monster???
post #337 of 645
Quote:
Originally Posted by kevin gilmore
There would be absolutely no reason why the input pot can't stay
exactly where it is, and a fiberglass extention rod added so that the
knob can be on the front panel with no impact on the audio quality.
Many designers do this.

KG - What is your opinion on using Stepped Attenuators on the interconnect cables between the source and the amplifier? Is this a sensible form of volume control?

Basically you take a good quality interconnect. Cut it in half and connect two stepped attenuators on each channel.

post #338 of 645
Quote:
Originally Posted by mbratrud
In theory (and in practice in my experience) there are quieter and more transparent methods of attenuation. I think this method is generally employed when remote control operation and price point objectives overide noise and transparency issues.
He could have used the beam deflection tube idea posted here awhile back. That would allow both remote control and control by a cheap pot, mounted anywhere you'd like.
post #339 of 645
Quality is definitely improving. However we don't have pictures of what
is inside the boxes. All dc coupling. Fet input with current source. Darlington
output transistor also with current source. I've been doing a fet input
with current source for more than 25 years. In general sounds like a
nelson pass aleph design. This 1990's design pretty much obsoletes all
of Rudi's other stuff. At least the thd is down to reasonable levels.
Still for the 010's it could be and should be 10 times better. Output
slew rates are definitely not symetrical. So you really need 2 x rp-010's.

Mikhail and Rudi are now in competition for 50 lb amplifiers. If mikhail were
to build a mig2 it would likely weigh in at over 100lb for the amp plus
power supply. Who would have thought that a simple headphone amplifier
would weigh more than even a very top of the line cd/sacd player.
This is all humour of course as my dynomite is likely to hit the 50 lb
mark too.

When you take an interconnect cable and cut it in two and put in
a step attenuator you end up with an impedance mismatch on the
output end of the attenuator. Unless of course you do 75 ohm everything
and a 75 ohm L pad attenuator in addition. Gets kind of expensive especially
in balanced form when you would need 8 decks. The 75 ohm thing is
important because both the jacks and plugs can now be had from wbt
that are true 75 ohm connectors. Best to have a standard step attenuator
inside the box. And i don't believe for one second that any pot no matter
how well made can possibly track as well as a step attenuator with
precision resistors.

Lets have a poll on the price... My guess $3800 usd.
post #340 of 645
Don't forget the Angstrom amps... one-offs, granted, but the two box probably weighs 50lbs per box.

I'll put in my vote at $4500.
post #341 of 645
Thread Starter 
About the potentiometer is a "customized" alps, the motor (of the RK27) in a RK40. As you an read in the web page, Rudi prefers the pot to the stepped... not all the hi.end amps adopt stepped, not a universal decision that the stepped is better in any way respect to the potentiometers, for what I know and IMHO.

About the price, at the moment: NOT FOR SALE !

Best!
Nicola
post #342 of 645
no indeed, a lot of high end preamps used stepped attenuators made of relays or digital volume controls

A black beauty is a bit better than a blue velvet though.
post #343 of 645
Here is a little more (directly from rudi's page)

Thech Specs ( lab measured)
Maximum Output: 500mW
Bandwith: DC -100.000 Hz within 0.3db
THD: 0.1% (output 3Vpp 1Khz -)

Now the sony specs.
Maximum power 1500mw impedance 70 ohms

Which would be 10 volts RMS for maximum dynamic range.

3Vpp at 1khz would be 3.2 milliwatts. What is the distortion at
32mw? What is the distortion at 320mw?

This is an amplifier specifically designed to maximise the wonderful
abilities of these headphones?????????

No wonder it is not for sale yet.

Reminds me of an old famous Zenith line.
"The name goes on before the quality goes in"

Really nice chassis work however. Thats what sells anyway.
post #344 of 645
Quote:
Originally Posted by kevin gilmore
This is an amplifier specifically designed to maximise the wonderful abilities of these headphones?????????
Now Kevin Gilmore, what's your point? Which of these specs show you that it isn't good enough to do the 010 justice? The output power? Come on! It seems you're about to cultivate your beloved animosity.

post #345 of 645
In the usa there is this little outfit called the federal trade comission that
specifies how amplifier power must be quoted. If the amplifier puts out
500mw then the distortion spec needs to be at that level. Not 100 times
less than that level. Some amplifiers have their best distortion specs at
low power, some amplifiers have their best distortion specs right before
clipping. Which is this.

The qualia headphones are certainly not ultra high efficiency headphones.
They really do need significant amounts of power to sound their best.

Rudi is in good company with another famous designer who obfuscates
his numbers too. Take a look in the october stereophile where the
halcro spec says 3000 parts per billion of distortion. And the real
stereophile numbers are .025%. A stereophile review of the rp-010 would
definitely be good reading.

Many people who listen to these headphones will do so with amplifiers
that do not have the capability to drive these headphones correctly and
will walk away with the wrong impression. These are not 300 ohm headphones
that are easy to drive. They also have significantly more inductance than
you might expect. Even sony has not decided how best to drive their
headphones.

There is more to designing an amplifier to a specific job than saying
you have done so and putting a "Hic Sunt Leones" on it.
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