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Leaf Audio PA-03 MKII Review (Tube Preampifier)

SIY

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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.
Preamps are now a niche category. And it's pretty trivial to come in under $100 for BOM of a top-performer if your case isn't too fancy, translating to about $500 retail.
 

nyxnyxnyx

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Preamps are now a niche category. And it's pretty trivial to come in under $100 for BOM of a top-performer if your case isn't too fancy, translating to about $500 retail.
Thank you for the answer. I do think it's niche or less popular now. I mainly use headgears and in many different communities, almost nobody is talking about preamps. The few times the topic comes up it is usually from the guys that already have one or are involved with speakers.
 

hmscott

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@gonzoucab - Congratulations on your new Leaf! :)

A quick search found these two audio sessions with the Leaf Audio PA-03 MKII Preamp+Mono Blocks, another with the only the Leaf Audio PA-03 MKII Preamp...

Leaf Audio: Pre PA-03 MK2 Tube, Monoblook PA-01 Class A 60W/Kênh, Class AB 250W/Kênh - YouTube

The Youtube auto-translate is amusing, it is tough to make out from the translation what he is communicating...

If I Were aBoy ทดสอบ Hifiman HM901R ภาค Dac - YouTube
And, he has a number of other listening sessions using the Leaf Audio PA-03 MKII Preamp: Jirapong Kusrisomsub - YouTube

Which reviews or listening sessions did you find before ordering that convinced you to purchase the Leaf Audio PA-03 MKII Preamp?

If you enjoy the Leaf Audio PA-03 MKII Preamp in your setup, I wouldn't worry about the measurements, but it sounds like you heard problems in the audio before sending it to Amir?

I've seen these listed on eBay and AliExpress. I had an ARC Preamplifier long ago, but the insides of the Leaf didn't remind me of the Audio Research build, and the LS22 had 8x tubes while the PA-03 only has 4x tubes, so I passed it by when scanning for Tube amps to drive my Hifiman HE6SE V2's + HE-Adapter.

It is tough to tell from afar which make/models are worth getting, so I extensively check out the forums, review articles, and youtube videos. Without independent measurements and a listening session (in person) before purchase, it is tough to know for sure what to purchase.

You can return purchases to China sellers, sometimes they have USA warehouses for support / returns, it is worth asking the seller, perhaps @amirm can ship out the return from his location to beat the return end date? Sellers may give push back, but be insistent and involve eBay/AliExpress Support if needed. If you are past the return period, ask if they will give you credit on another purchase..

As a newbie audiophile I wouldn't be discouraged, as there are ups and downs in learning any new hobby. Perhaps you can tube roll to improve the sound to your liking? If you are unable to return it that might be worth a try before performing more extensive modification surgery.

These are the tubes listed by this AliExpress seller as compatible:
Standard electron tube: Chinese 6N11 electron tube x 4 can be replaced by E88CC, 6922 and 6DJ8

Here are a couple of suggestions for compatible tubes. The first are NOS (New Old Stock) 1972 - about $50/tube is typical for true NOS tubes - not used pulls but actual New Old Stock never used tubes, and then a Quad of new issue Genalex Lions - about $36/tube:
Matched Quad Tesla NOS/NIB E88CC/6922/6dj8 tubes Gold Pins - 1972 - Tests NOS | eBay - Original Czechoslovakia made
PLATINUM Matched Quad (4) Genalex E88CC/6922/6DJ7 tubes Gold Pins - Russia | eBay

I've found Nikolay is a reliable seller over a number of purchases. He also maintains a tube info site. I can recommend other sources, but Tube Maze is a great start, and he offers 30 day returns:
Tesla E88CC Gold Pins - Tube Maze
Tube Maze - Guides and reviews of vacuum tubes and tube equipment

Those are the recommended budget choices - there are cheaper alternatives, and Rick and Austin at Viva Tubes have been reliable for me as well, they offer 60 day returns:
Brand New Electro-Harmonix 6922 E88CC GOLD PINS Matched Quad (4) Vacuum Tubes 844632064210 | eBay
Gain Matched Quad (4) JJ 6922 / E88CC / 6DJ8 / ECC88 Vacuum Tubes - Brand New | eBay
VIVA TUBES | Thousands of vacuum tubes always tested, matched, and guaranteed

And, there are also more expensive choices:
Amperex 6922 | eBay

Amperex 6922 tubes are highly desired - you can see the prices - and this listing caught my eye as the measurements indicate NOS 100%+ and are only a little more expensive than the Tesla Yellow label 6922's I listed above. IDK this seller, but he has a 100% rating on 2678 transactions, but doesn't take returns. These are worth a shot, but I'd also get either the Tesla's or the Genalex as backup - and to compare the sound for your tastes.
AMPEREX JAN 6922 E88CC Gold Pin low noise preamp tubes quad 6DJ8 USA | eBay

You might want to start up a conversation with those sellers, explain your situation, perhaps share Amir's review and ask them what tubes they would recommend.

Given my experience with the stock China tubes I can recommend trying tube rolling to improve the sound.

Also, given complaints I've heard about China shipped products from others, it is worth going through the unit to find cold solder joints, unsoldered joints, loose ground lugs, loose fasteners in general, and simply reseating the tubes given they've been jostled about during long shipping voyages. So far I haven't experienced any of these issues, but it is worth checking to make sure. :)
 
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restorer-john

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Preamps are now a niche category. And it's pretty trivial to come in under $100 for BOM of a top-performer if your case isn't too fancy, translating to about $500 retail.

I guess that's true if you classify a "preamp" as a simple single input line stage with a volume control.

A preamp was a device which brought together multiple disparate sources, with differing output levels, impedances and requirements, along with a switcher, monitor loops, signal routing, filters and tone controls along with a robust line driver and likely a high grade RIAA MM/MC stage as well as full IR remote control and power amp trigger switching.

Do that in 2021 for $100 or $500 retail with SOTA performance. It won't happen.
 

Labjr

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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.

They probably just copied another VU meter and didn't even notice. It shows how they just rip off everything without an original idea or improvement. Why it measures terrible.
 
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SIY

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I guess that's true if you classify a "preamp" as a simple single input line stage with a volume control.

A preamp was a device which brought together multiple disparate sources, with differing output levels, impedances and requirements, along with a switcher, monitor loops, signal routing, filters and tone controls along with a robust line driver and likely a high grade RIAA MM/MC stage as well as full IR remote control and power amp trigger switching.

Do that in 2021 for $100 or $500 retail with SOTA performance. It won't happen.
A few rotary switches and two opamps. Two more opamps if you want tone controls. Remote and such is a frill for the higher priced spread.
 

restorer-john

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A few rotary switches and two opamps. Two more opamps if you want tone controls. Remote and such is a frill for the higher priced spread.

Rotary switches are terrible and you know it. Crosstalk/breakthrough goes out the window. Long term reliability is horrible. Line up those inert gas filled relays and short the signals to gnd. Do it properly or not at all.

And we want a decent MC and MM front end. Sure, you can do it with a pair of opamps, but they need a quality sub power supply and anything decent will need two separate and optimised gain stages. Not trivial and not cheap in this day and age.

Tone controls and filters, easy enough, but keep that noise low all the way through.

And remote volume is a "frill"? Seriously in 2021? No way, volume is essential. Sure, I agree, I get up and turn my volume pot (mostly), but an Alps blue motorized dual 50k log pot is a quarter of your already thin on the ground BOM.
 

SIY

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Rotary switches are terrible and you know it. Crosstalk/breakthrough goes out the window. Long term reliability is horrible. Line up those inert gas filled relays and short the signals to gnd. Do it properly or not at all.

And we want a decent MC and MM front end. Sure, you can do it with a pair of opamps, but they need a quality sub power supply and anything decent will need two separate and optimised gain stages. Not trivial and not cheap in this day and age.

Tone controls and filters, easy enough, but keep that noise low all the way through.

And remote volume is a "frill"? Seriously in 2021? No way, volume is essential. Sure, I agree, I get up and turn my volume pot (mostly), but an Alps blue motorized dual 50k log pot is a quarter of your already thin on the ground BOM.

Well, if you want every bell and whistle, fine. $600.

The crosstalk thing is somewhat irrelevant, never seen it ever approach anything audible. If it's really critical, it's an easy and very low added cost fix to rotary switches. I haven't researched it, but electronic switching these days is likely just as cheap or cheaper; I go with rotary switches because of my own inertia.

Top quality opamps are cheap. Circuit boards are cheap. Seriously, you're making it far more complicated than it really is.
 

don'ttrustauthority

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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:
I've been lost without knowing how Dolby level relates to 0 db.
 

Phorize

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Well, if you want every bell and whistle, fine. $600.

The crosstalk thing is somewhat irrelevant, never seen it ever approach anything audible. If it's really critical, it's an easy and very low added cost fix to rotary switches. I haven't researched it, but electronic switching these days is likely just as cheap or cheaper; I go with rotary switches because of my own inertia.

Top quality opamps are cheap. Circuit boards are cheap. Seriously, you're making it far more complicated than it really is.
If you can make it look like this I’ll buy one:

https://i.pinimg.com/originals/d5/10/e8/d510e8386625db2c6740e50a2aa79b0c.jpg
 

pseudoid

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...Even if we go with your cow sh!t analogy...
but that analogy misses the fine point which may make a big difference: Like stepping in WARM sh!t would feel much worse than on COLD sh!t...
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?...
This preAmp's unique point (no one has made yet) is that maybe you are paying the extra $$s for the EVEN harmonics... like the 'cold-sh!t' analogy ;)
 
OP
amirm

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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?
If you are going to route the state of the art DAC signal through it, it needs to be darn good and clean. Topping 90Pre which I have tested is one example. You could also ask for stepped relay for perfect channel matching and such. Plus remote.
 

MaxBuck

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I guess that's true if you classify a "preamp" as a simple single input line stage with a volume control.

A preamp was a device which brought together multiple disparate sources, with differing output levels, impedances and requirements, along with a switcher, monitor loops, signal routing, filters and tone controls along with a robust line driver and likely a high grade RIAA MM/MC stage as well as full IR remote control and power amp trigger switching.

Do that in 2021 for $100 or $500 retail with SOTA performance. It won't happen.
The problem is, the source componentry has changed so much over the years. Phono is coming back into vogue, but AM/FM tuner usefulness is approaching zero, and pretty much no one is using tape or similar linear media to "record" material. Very much shifting sands from the perspective of exactly what a preamplifier needs to be able to do. One could argue that Bluetooth and streaming capabilities should be required for a 2021 preamp.
 

restorer-john

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The problem is, the source componentry has changed so much over the years. Phono is coming back into vogue, but AM/FM tuner usefulness is approaching zero, and pretty much no one is using tape or similar linear media to "record" material. Very much shifting sands from the perspective of exactly what a preamplifier needs to be able to do. One could argue that Bluetooth and streaming capabilities should be required for a 2021 preamp.

I totally agree. The previously essential AM/FM tuner is dead and buried. I haven't plugged one in for well over a decade.

An MC/MM phono stage in a preamplifier alongside (or near) a Bluetooth or WiFi transceiver is going to be fun and games for noise.
 

FTB

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Hi,

About how much distortion we can detect, try this :

Very useful.
It's interesting we are way less sensitive to distortion on music, the result could surprise some I think.
I'm not saying it's ok to buy electronic gear with so much disto.
 

MakeMineVinyl

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Perhaps more companies should label the inputs on their preamps with numbers rather than what is 'supposed' to be plugged into it. After all, a line input can accommodate an AM/FM tuner just as well as a cassette deck, open reel, DAC or VHS tape audio for that matter.
 

Hifihedgehog

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mhardy6647

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FYI the AC/DC switch which is for the tube filament doesn't do anything (it says so in the specs and I tested it as such).
Wait, what? Doesn't do anything audible/measureable... or doesn't do anything, full stop?
Is the switch not connected to anything?
The specs say "this switch doesn't do anything"? If so, do they offer any suggestion as to why it might be there?

:oops:

I'd be interested to measure the filament supply to the tubes with the switch in each position with a voltmeter.

EDIT:
I googled and, indeed, I see that they say exactly what you wrote! :facepalm:
9. Filament power supply AC and DC switching (note: filament AC power supply is temporarily cancelled, please contact us if you need filament AC power supply)
source: https://www.aliexpress.com/item/1005002511786602.html

I am going to highly recommend the Leaf Audio PA-03 MKII as a decorative item. Hook up a spare output to it and have its VU meters dance around. When visitors come, tell them it is actually doing its thing. No sense in being honest with them and ruin the fun. And watch then praise the liquid mids and wonderful soundstage of tube preamp.....
Quote of the day, right there. :)
There was a raft of equipment in the "golden age" of which the same could be said, I fear...
 
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MakeMineVinyl

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There was a raft of equipment in the "golden age" of which the same could be said, I fear...

If you mean the 1950s - 1960s, I'm not aware of any tube gear which wasn't designed to be as transparent as was possible with the available technology. The Fisher, Scott, Marantz, Mcintosh of that era may have had differing ways of achieving that goal, but they weren't the snake oil hucksters we have now, with this preamp being the poster child.
 
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