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In Reply to: RE: Stereophile December Issue Was Excellent posted by Sprezza Tura on November 16, 2014 at 10:45:06
I purchased the KX-R with the intention to upgrade.
Follow Ups:
why do you need an active preamplifier?
All preamps, no matter how 'good' change the SQ.
I own and evaluate DACs with no volume control feature or a digital volume control. I have yet to find a digital volume control that outperforms the Ayre KX-R. Updating the KX-R and ultimately my MX-Rs will result in more accurate component evaluations and superior sound for my system.
then use a passive constant impedance unit such as a Placette. My made to order balanced unit outperforms any Stereophile Class A or whatever + they put on units these days that I have owned and heard.
Thanks for the suggestion Fred.
With all digital sources outputting more than enough voltage to drive any power amps, an active preamp is an additional gain stage that is superfluous.
I am not suggesting using digital volume controls, I agree they suck. An passive is your best solution with out a doubt in my mind. Don't any of your DACs have high quality analog volume controls?
Even Charles Hansen said that preamplification is unnecessary and was devised as a way for manufacturers to sell an extra box to its customers.
Read Art Dudley's review of their flagship integrated with passive input stage.
...Charles Hansen said here in a discussion that an good active preamp actually improves the sound although even he is not sure why that is.
It tends to increase dynamic contrasts and make the music sound more alive for one thing - perhaps due to better impedence matching.
Absolutely agree , active pre-amp trumps passive setups all day , unless one is into dead soft passive sound ...
Regards
Charles on active preamps .
I've been a passive attenuator enthusiast for over a decade, but recently replaced my old active with a new one. I'm inclined to agree with him now.
Good link, thanks.
with another inmate about this topic. While I certainly don't claim to know the answer, he said he found a pre/power amp combination that created "false" dynamic range via "jumpiness". When asked as to the specifics, he declined.
Short of distortion or the attempt to increase dynamic range via a DBX type device, I am not understanding how a component can exaggerate dynamic range.
I'm with you on that.
I think both active and passive approaches are valid. If a pre/power combo created "artificial" dynamics, then they are just bad components.
Personally, I prefer a tubed active linetage with a solid state amp, and a passive TVC with a tube amp. That is just my preference for the most balanced sound.
CH's post was smart because he hedges his bets, because there is no right answer. IMO there are a few passives that approach his ideal.
And take note, what he says is absolutely true. Budget, or Midpriced preamps are just a waste of money. He says in no uncertain terms a truly grain free preamp will cost you. A cheap pre can absolutely destroy a system's performance.
I know many have state they prefer active for things like "dynamics", and impedance matching is a factor, but transformer based passive solutions take care of that very well.
Here is an interesting quote from Art Dudley's AX-5 integrated amp review:
"As Hansen explains, most active preamplifiers work by applying to the input signal a certain amount of voltage gain, so the signal can effectively drive a power amplifier. But in order for there to be a reasonable volume range—and to simply keep the playback level from being too loud—the voltage-gain stage is preceded by a potentiometer, which attenuates the signal. The drawback of this is that such a preamp will exhibit its maximal signal/noise ratio only at its maximal (unattenuated) volume. As Hansen puts it, "Since most preamps are used anywhere between –10dB and –40dB for an average listening level, this means the S/N ratio in actual use will be 10–40dB worse than on the spec sheet."
Read a little bit more; this is how most preamps work. Not the Ayre KX-R and other Ayre preamps (I'm not sure about the entire line of Ayre preamps and integrated amps).
Edits: 11/17/14
has been doing it for years; it doesn't make their active preamps sound better than the rest.
Many of the techniques to improve preamp performance have been around for years I have used or heard these.
Lucy decided to provide us the following comments:Passive preamps are sub-optimal.
Plain pots really don't like to have their wipers loaded. It causes distortion. The capacitance of a cable accounts, too. It requires current to charge when a signal is applied. Wipers distort when they are asked to provide current.
Those Vishay foil resistors actually have measurable flaws. Forget about the Placette.
http://www.ap.com/download/file/747
Transformer based units have the usual transformer limitations.
Plus... A good preamp also provides some manner of common mode rejection.
Certainly all the Ayre units do. Think that matters?Finally... An AX-5 is basically an econo version of my KX-R preamp, but with larger resistors in the volume control to give it voltage gain. Obviously, the output buffer of the KX-R is WAY heftier, as is the power supply.
Edits: 11/18/14 11/18/14
let Lucy bark his/her reply
Lucy is a little girl, but she delivers a big bite!
that those who barks loudest (bites as well) have the least to offer?
...I don't doubt it!
Good thread, thanks for starting it. A rare occassion of sensible debate and give and take on a subject (which the thread veered towards) where there is no right or wrong.
Yes, I am aware. Actually the review I quoted from mentions that.The entry level integrated and preamp do not use this topology, I am almost certain.
Why you would need a $20,000 preamp with today's digital sources is beyond me.
Edits: 11/17/14
It's actually $27500. I also have vinyl.
I like it because it has a beautiful case :)
These milled from solid stuff is a monumental waste of resources and presumably arise because there is plenty of unused CNC capacity in industry.From an environmental viewpoint, it is wasteful. From a technical viewpoint, who knows? From a cash point of view, it is the ownership motive at work for those who have spare cash.
I'd rather invest in art objects.
Edits: 11/17/14
Whether you mill-off unwanted material with a CNC machine or shear it off with notchers and punches the result is the same, a bin of very pure Al. to be remelted.
The difference is labor, with CNC you don't need carbon-based units to do the chopping, punching, bending and welding. That means we can reduce the breeding rate which has all sorts of environmental benefits for the planet. CNC is Green....
Rick, the environmental sensationalist.
No, the difference is:
cost of billet
cost of investment
cost of assembly.
CNC machining like so is intended for structural integrity purposes, not for selling something at x times what it should cost.
CNC’ed aluminum cases are better for shielding due to their thickness. Aluminum doesn’t do squat for low frequencies - you need steel or something magnetic. But, that adds electrical distortion. The Navy did a study on that decades ago - most of their vehicles are really large steel vessels and they find their way through various sonic tricks. Aluminum doesn't add nearly as much distortion, but if it’s thick enough the Eddy current losses do make for good shielding. Not to mention the better mechanical resonance issue.
There’s also the air flow aspect and how that effects thermal properties of components. A real advantage of CNC boxes is that you can have a heat sink connection anywhere you want. This isn't just an audio thing, either.
LUCY
sink connection anywhere you want - why? not true
Do you know that smeltering an Al billet and then shaving this off is one of the most polluting activities that can be undertaken in material processing?
what you say about thickness and shielding is not true either. If maximum EM shielding is needed, then the Al cavities need to be lined with Mu metal and the like.
Why does anyone want to pay over$25000 for a preamp in a 'value ehancing' box?
Some of the better sounding preamps are housed in Acrylic!
I would suggest that most of the expensive preamps are housed in "beautiful" cases. When you're dealing at this price level, pride of ownership enters into the picture-so I'm told by industry people.
If you look at the image of the KX-R, you will see isolation of the component compartments that has obvious benefits.If you don't want to spend this much coin, I totally understand. But to suggest that the case is simply for looks, just ain't so.
Edits: 11/18/14
much does it cost in % terms to program the CNC for a limited run because of the $27000 price?
I didn't say anything about value. You said you wanted the case as a reply dismissing passive attenuators, with a lot of garbage quoted from Lucy's barks.
"how much does it cost in % terms to program the CNC for a limited run because of the $27000 price?"
A good deal of money.
"I didn't say anything about value. You said you wanted the case as a reply dismissing passive attenuators, with a lot of garbage quoted from Lucy's barks."
I'll refer this statement to Lucy.
using TLCs to 'enhance' SQ. Introduce a bit of magnetic non linearityand 'dynamics' are improved?
The wiring looms in these things are disgusting but guys who complain about RF and pickup seem to love 'em.
"Don't any of your DACs have high quality analog volume controls?"The MSB Technology Analog DAC, but there are some real limits with this DAC.
My Ayre MX-R amps have only balanced inputs. The Analog DAC's balanced outputs are a compromise. I guess one could solve the issue by purchasing an MSB Platinum or Diamond DAC.
Edits: 11/17/14
Understood.
If you really did want to pursue a passive approach, which I believe would absolutely yield the very best results there are several SOTA passives with balanced and single ended inputs and outputs.
Side note..if you are not running a system balanced from source to amp, I don't see the point.
there are very few passives with balanced constant impedance operation that has fine steps. My Placette does 0.1dV above a certain volume and 1dB below that.
1 dB is simply not enough.
Apart from the Placette, I have a Carver Lightstar Direct which does not have the all Vishay resistors that the former has. It does 0.5 dB balanced passive and the active unbalanced line sounds poor in comparison.
Music First's TVC's are superb and the same with Townshend.
For Light based, you should check out Tortuga.
From Townshend website:
''Input impedance is dependent upon the load impedance and gain setting. So, with a power amplifier having 20kohm input impedance (typical
The Allegri Passive Autotransformer has a six position input selector, a mute switch and a 24 position volume control with intervals chosen to cover a wide range of volume levels in different systems''
Thus:
Variable Impedance
24 steps far too coarse
These are unacceptable features for me because they create major issues in use.
Thailand seems to be the source of many of these TLV transformers and one can buy them to experiment with. As I said, the wirelooms created in assembly are not nice for mutual and external pickup.
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