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Leaf Audio PA-03 MKII Review (Tube Preampifier)

SIY

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I'm not so sure there isn't some way to scientifically ascertain and record subjective impressions and thereby preferences, but I agree it hasn't been done.

Read my article on controlled testing Hedonic analysis is well established. Floyd Toole wrote a whole book about it.
 

SIY

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Hey Amir what if we swapped the tubes in that sucker? What do you think is broken? Can you fix it??

That's a topology and operating point issue. I'll be receiving it in a week or two and do an analysis. If it's easily correctable, I'll do that as well.
 

HiFidFan

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Dont know how good this poweramps are. But with this preamp they are fu**ed. ;)
Would be interesting what we realy could get for this amount of money?

I'd like to see them tested here, but at the asking price I doubt that will happen.
 

HiFidFan

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Don't mess with the asthetics but make this sucker solid state and include, internally, a SOTA DAC. Take my money!
 

Gorgonzola

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Hello,

Au contraire you are just not paying attention.

The Harmon Headphone Curve was created/developed with controlled subjective input from human subjects.

Put a pair of headphones on a few dozen test subject heads, hand them a box with a couple of knobs to adjust the sound to their preference, after some number crunching Sean Olive PhD published his objective Harmon Headphone Curve.

There you have it, an example of controlled subjective meets objective. Harmon takes it to the bank.

Thanks DT
Thank you, yes. I think this is an example of scientifically correlating subjective preferences with performance parameters. Although that significant differences in frequency response are generally conceded, where as the way relatively small differences in distortion are not. Geddes/Lee work is headed in that direction however, as I understand.
 

egellings

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I wonder if it's possible that you got a broken copy of the preamp. It's pretty lousy, nearly broken. I don't think that any preamp needs to hit 13 Vpp or so; no power amp would ever use that much on its inputs. Whew!
 

restorer-john

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That's a topology and operating point issue. I'll be receiving it in a week or two and do an analysis. If it's easily correctable, I'll do that as well.

Please present a follow-up thread in due course. Hopefully, with a reverse engineered schematic of the section or stage/s with issues and what can/can't be easily done to fix/improve it.

Also, perhaps see whether the "VU" meters correlate in any way with the rated output of the unit or are they just there for show.
 

MakeMineVinyl

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Also, perhaps see whether the "VU" meters correlate in any way with the rated output of the unit or are they just there for show.
I'm really dismayed by the current fad with VU meters, although its been a fad in the past. VU meters used to serve a specific purpose and had highly standardized ballistics. When I see VU meters on units like this preamp, it just screams gimmick, since there's no way on earth that "0" VU means anything that's of use to any end user.

I think I'm just in a crotchety mood today...... :confused:
 

NTK

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I'm really dismayed by the current fad with VU meters, although its been a fad in the past. VU meters used to serve a specific purpose and had highly standardized ballistics. When I see VU meters on units like this preamp, it just screams gimmick, since there's no way on earth that "0" VU means anything that's of use to any end user.

I think I'm just in a crotchety mood today...... :confused:
Of course they are gimmicks. In these day and age, why would anybody that actually needs one uses some electromechanical device instead of an all solid state solution.
 

Labjr

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I'm really dismayed by the current fad with VU meters, although its been a fad in the past. VU meters used to serve a specific purpose and had highly standardized ballistics. When I see VU meters on units like this preamp, it just screams gimmick, since there's no way on earth that "0" VU means anything that's of use to any end user.

I think I'm just in a crotchety mood today...... :confused:

Yeah some of these Chinese brands are making cookie-cutter hifi with gimmicky features. I guess they're chasing the Audioquest buyers.
 

restorer-john

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Of course they are gimmicks. In these day and age, why would anybody that actually needs one uses some electromechanical device instead of an all solid state solution.

Because the physical movment of large moving coil meters are hypnotic. It's a hark back to simpler times and a nod to the power stations, factories and test equipment which all look so cool in miniature on a piece of HiFi gear.

That said, unless 0dB is rated output and the ballistics are such that they reasonably capture the peaks, it's otherwise just eye candy.
 

NTK

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Because the physical movment of large moving coil meters are hypnotic. It's a hark back to simpler times and a nod to the power stations, factories and test equipment which all look so cool in miniature on a piece of HiFi gear.

That said, unless 0dB is rated output and the ballistics are such that they reasonably capture the peaks, it's otherwise just eye candy.
Don't get me wrong. They are definitely mighty cool looking, and I definitely wouldn't mind one for myself. I think there would a market for Leaf Audio if they just sell the chassis with the VU meters, and let people stick in their Hypex/Purifi/Pascal/Ice/Orchard etc. modules.
 

CedarX

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Don't get me wrong. They are definitely mighty cool looking, and I definitely wouldn't mind one for myself. I think there would a market for Leaf Audio if they just sell the chassis with the VU meters, and let people stick in their Hypex/Purifi/Pascal/Ice/Orchard etc. modules.
As a matter of fact, an almost identical chassis is sold on AliExpress by BrzHifi for $68 + $84 shipping (and some others stores at similar prices). The front plate is labeled Brzhifi and the rear plate is blank. The VU meters, knobs and feet’s are included.
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MakeMineVinyl

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As a matter of fact, an almost identical chassis is sold on AliExpress by BrzHifi for $68 + $84 shipping (and some others stores at similar prices). The front plate is labeled Brzhifi and the rear plate is blank. The VU meters, knobs and feet’s are included.
View attachment 150177
View attachment 150179
View attachment 150180
HA! Those meters look like leftover old stock originally made for a Dolby tape deck - notice the Dolby marks at "0". I guess they're counting on nobody being still alive who knows what those ancient artifacts are. :oops:
 

CedarX

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HA! Those meters look like leftover old stock originally made for a Dolby tape deck - notice the Dolby marks at "0". I guess they're counting on nobody being still alive who knows what those ancient artifacts are. :oops:
:facepalm::facepalm::facepalm: The only thing they brag about… are the dimensions! Amir could invest in a Precision (non audio) Tape Measurement equipment and start another series of reviews unequivocally based on science. Who knows if some fancy purifier could improve the dimensions dynamic! :p:p:p
https://www.scullyandscully.com/gif...silver-womens-gifts/sterling-tape-measure.axd
 
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amirm

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HA! Those meters look like leftover old stock originally made for a Dolby tape deck - notice the Dolby marks at "0".
That just means it was designed to go on a cassette deck with Dolby noise reduction. Not that there was a Dolby branded tape deck that went with them.
 

nyxnyxnyx

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I have a question to designers and long-time followers here: At a high price point (let's say $1000+) for a preamp, what should be the unique selling point of it? And how many % of the total price actually go to the components of a preamp?

I'm asking because while I understand the use-case of a preamp, I don't know how hard it is to design a SOTA one. And as far as I know, some types of products don't require or benefit much from a preamp.
 
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