Leaf Audio PA-03 MKII Tube Pre-amp: Full Test and Review
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- Опубліковано 29 бер 2023
- This is a full technical review of the made in China Leaf Audio PA-03 MII Tube Pre-amplifier. It is a clone of the ARC LS22 and turns out to be surprisingly good. The tested version is the The "ABCD upgrade" model with Capacitor Board Upgrade, MUNDORF Oil Immersion Capacitor, and Philips 6DJ8 tubes.
It's not exactly the same as the version tested by Audio Science Review which might explain why this one tested wildly different, but also could be their sample was defective? All I can say is this one I tested is worth looking at if you are in the market for a pre-amp!
Here is my Patreon, as well as the donation page at my site, if you feel so inclined to help fund some of the future projects for the channel!
www.patreon.com/user?u=87080658
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Very nice review, Skunkie! The difference between you and the hifi reviewers is that you know a lot of electronics,you know how all this devices works and you know about components, design...and all that are very important.
Great review Stephe. It is really great to see a proper analysis
Such a good quality review. Amazing. Good job!
You are the best! I learn so much from your videos. Thank you!
Thanks for posting this video. That's the exact same amplifier I own, with pretty much the same upgrades. You have a choice of a total of 4 possible upgrades, A,B,C and D. Each letter representing a different type. That one probably got all four, I just chose an upgraded potentiometer and capacitors because of budget limitations. I run a subwoofer out this preamplifier because my power amp doesn't have the output for one, and it all sounds fantastic. Yes, this is the only tube amp they sell.They do also offer a SS power amp, and SS monoblocks, whoever "they" actually is. Anyway, I'm glad your scope backed up what my ears have been telling me all along... this preamplifier is well made and legit. I will eventually upgrade the tubes one day, but for now they sound pretty dang good. Thanks again!
Enjoy everything about the channel and I learn so much about different aspects of amps, wiring, soldering and diagnostics, love it
Awesome, thank you!
Absolutely fantastic vid. I don’t ever want to be argumentative with my comments, as that’s not my nature, but I kinda feel like Amir almost enjoys “testing” gear and saying it’s snake oil or just plain BS. Of course there’s plenty of that in the world of HiFi, which is why I enjoy DIY projects, mods, and upgrades to gear to get the most out of my system and understanding how it works.
I appreciated your videos very much as well as the way you approach things. Over the years, if I’ve learned anything, it’s that with a bit of effort and knowledge, one doesn’t need to spend many thousands of dollars to get great sound quality.
Thanks for everything, Steph. 👍🔊😊🎶
Great review. The preamp is obviously better than most expected.
Thank you so much! I've seen a couple videos on your channel and I regret not subscribing before. This time I did. Also, I've been looking at this pre-amp and wanting to get it, but I hesitated due to fact that is made in China. I might consider it after your extensive and clarifying review. On another token, I'd love to see more women with an engineering background interested in audio doing such a good job. I also am into audio with a humble understanding on electricilty principles. Again, thank you so much. Your gained a follower and an admirer.
Your description of the purpose of these things describes what I did years ago: put a Counterpoint hybrid preamp between my CD player and SS amp, just to tone down the harshness of the CD.
Great channel Skunkie! Thanks for your though tests and reviews. Everything explained very clearly and with common sense. (FYI - Leaf Audio is readily available on the Chinese websites. They make various integrateds and power amps as well)
Hmm nothing shows up on a google search other than www.leaf-audio.com/ which isn't the same folks.
Nice review :) I was thinking about adding one to as atube buffer and a volume control to a pair of Schiit Audio Gjallarhorn's.
Skunkie, Your report on that pre amp makes me wanna buy one for myself. Thank You! Also my power amp does not have a volume knob. It is even shipped to europe, except I only found them with 110V mains voltage.
Hope your feeling better 🎉
I am!
They are a brand that has existed for more than 10 years. But they are probably small. They have a shopfront in the Taobao app or website but the language is in Chinese. I happen to buy from them the 10th Year Anniversary edition of their dac that uses wm8741 chip. The 10th yr edition uses 4 wm8741 chips and has cpld implementation. I communicated w the designer of Leaf Audio before the purchase. I told him that in the states someone made mention of his preamp but he told me he has no access to youtube. I will pass him this video link, hopefully he can watch it one day. They also make integrated amp, monoblock, LPS etc. Their local Chinese customer base seems very loyal to the brand and even within the Chinese market their products are known to be value for money. They are unlikely to place fake components in their machines as their local customer base is discerning.
Thanks for the info. I hope my review clarifies some things, as the ONLY other mention of this product in a google search is a scathing review at Audio Science Review.
I thought your review is so well done as it is based on facts and you are also very kind to Amir who has different findings. I will be very interested to send you an excellent Chinese preamp that I am using. But alas, I am not in the States. Btw the Leaf Audio designer agree w your findings - that after defeating tone controls, treble and bass need to be maxed to remove all distortion. I also asked him about the VU meters. He told they give a sense of the level of the output signal, but it is more for cosmetic display rather than accuracy.
As I noted the zero point on that meter did correspond to the point where distortion went over 0.1%. I'd be happy to review any future gear like this, but as you said shipping becomes a problem.
Interesting run through. I wonder how those balanced transformers on the XLRs perform...?
PREACH 100! 💯 great views
Amazing work. About unity gain, even using solid state amps, it makes sense having like x6 times gain from tubes to bypass the amp's input buffer and gain stage (opamps). Also output impedance of tube amplifiers should have a buffer low enough to drive the amp load. i.e: Purifi amps have 2.2k input impedance unbuffered and require 10V to reach max power. If we use the amp's buffer, we'd be using two buffers at the same time, not sure optimal.
Thanks for the tips!
Nice review, thanks. I like the look of this preamp, it's got that Luxman kind of design. I suspect the ASR review was done using only the balanced inputs/outputs as it looks like the preamp is using small transformers for these, that would explain the higher distortion in general and the extreme distortion at low frequencies. I did find it a bit peculiar that the ASR review was done at 4 Vrms as that is a lot higher level than what you get from regular sources. Anyway, it would've been nice if the preamp had a phono stage and configurable gain, maybe something like 0dB, 6dB, 12dB. I guess replacing a couple of resistors could set the gain, but it would've been nice if they had some jumpers or maybe a switch on the back.
A good tube phono stage would add more tubes and not sure there is room inside for one. I don't know what caused the poor ASR results but my test methods using the RCA jacks seem fine.
I watched your video and bought the same preamp in China for 4000 RMB.
Man that was an awesome review...outstanding job on figuring out that tone defeat/tone control issue. That was some seriously key information with this unit. I don't normally mess with tone controls and it would have never occurred to me to turn them Both all the way to the right with the button pushed in if something wasn't sounding right. It's something I never would have tried lol. When it comes to preamps I agree that if they can be avoided (Dac with volume control) it's best to leave them out. So when I'm looking at a preamp its for the extra inputs as well as the extra output (subwoofer) Although I've used RCA Y splitters out of my high powered volume dac in the past. I also as well like the sound of a tube pre on my solid state. Which I'm curious what the Output Impedance of this Leaf preamp is? Nice shout-out to Amir and ASR, I'm a big fan of his content and forum. And no I don't always equate good measurements with good sound but measurements can tell you a whole lot about a piece of gear. Excellent video and content!
I have to assume the unit tested by ASR was either defective, the tubes had issues (super cheap china tubes maybe?) or this unit I tested is wired different. The only other thing that could explain it is I tested it using the unbalanced RCA and possibly the implementation of XLT/balanced is really bad on this unit?
@@SkunkieDesignsElectronics yeah it could have been either of those issues or maybe even something else. Wouldn't be the first time he's evaluated a broken piece of gear. A bad tube or tubes would have tested wonky for sure.
Volume controls in current DACs aren't really ready to replace a good preamp yet.
@@YouSoundButtHurt yeah I get what you are saying, depending on the quality of the preamp though in my opinion. The one dac that I personally use for a preamp at times is the RME ADI-2 FS...which has been better (quieter/dynamic) than some pre's I've used. They've done well with their analog/digital volume control design. I get what you are saying though.
@YouSoundButtHurt So you are using an amp with no volume control?
One Ali seller has this line that I believe relates to that additional board:
"1. Optional power supply upgrade kit (refer to German power black box for OCTAVE tube amplifier)"
They also state:
"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)"
Update: I found the 'Octave Super Black Box' that has ten large caps of similar size to the upgrade board in the PA-03 MII. Octave's description is:
"OCTAVE, with the Black Box technology, offers an instrument to optimizing the OCTAVE amplifier in respect to the speaker. This flexibility is a unique feature of the OCTAVE brand.
The dynamic and tonal stability of an amplifier is strongly dependent upon the stability and capacity of the power supply, therefore the Black Box and Super Black Box were developed as external upgrades to the OCTAVE amplifiers’ power supply storage capacitors by increasing their capacitance by a factor of 4 (Black Box) or 10 (Super Black Box), respectively. This is a tremendous benefit if the speaker is difficult to drive. Loudspeaker efficiency is made less critical, while the amplifier is enabled to handle speakers with minimum impedances as low as 2 Ohms.
The power supply capacitance increase realized via use of the Black Box or Super Black Box stabilizes current delivery and reduces the impedance interaction of the load. This improves dynamic range, separation, depth, soundstage size and articulation, rendering the musical reproduction clearer throughout the entire frequency range. The amplifier remains unaffected by mains variations and interferences due to the noise filtering characteristics of the capacitors."
This appears to be designed for adding extra capacitance to an amplifiers power supply so why incorporate it into a pre-amp?
Just yesterday I was looking up the BOYUU Q6 preamp, which I've seen a couple positive User Reviews, one being Thomas and Stereo. I found 3 different China sellers, one seller had 2 upgrade options....Voltage Stabilizer upgrade $45. Transistor Voltage Stabilizer $115. I had no idea what this meant.
Great review 👏🏻👍🏻Amir uses 2V input and tone defeat.
I played with 2VRMS input on the scope and didn't see any change, so who knows why his was going bonkers on the scope?
@@SkunkieDesignsElectronics To me Amir didn’t care, he measures unit by unit with his method’s. Not near as passionate as you🥳
@@thomasfi1275 definitely..this is why I thought Skunkie's review was absolutely stellar
Great review as always. Really curious how your FX audio tube 01 compares.
Coming soon!
Looking forward to it
Tone knobs are loading the circuit. They did not completely remove them from the circuit in the switch.
Thank you Skunkie for this, and all your videos. I find they all are extremely informative. Did you found this preamp leaking DC?. My current tube preamp destroyed the input of 2 VMV A1 amps before I realized that it was leaking 15VDC, so now I want to purchase a good and safe preamp.
Not that I know of
Hi @@SkunkieDesignsElectronics . Could be a bad design the cause for a preamp leaking such high DC, even with volume to min?. Is it something I should be worried on at the time of choosing a new tube preamp?.
Any tube amp is going to have a DC blocking cap on the output. If there is DC on the output, that cap is leaking DC.
Oh this is cool
good
i wish they would sell just the chassis with the vu meters so i can build a hypex amp in it.
It is a cool chassis!
was it a ringer?
A viewer ordered it from one of the china HIFi sites, and then sent it to me to look at for him. Whoever sold it had no way to know this would eventually end up on my UA-cam channel!
Agree, there is no point to a product like this today. In the digital streamer world, there is zero need for a preamp and the only effect is to veil the sound. Even with analog and MC cartridge there are better solutions.
@@matthewtaylor7355 That's not being my experience. The solution that is the least damaging to the sound is a unity gain Jfet buffer with volume control. So you can set your streamer/dac volume to the max and avoid decimating the digital signal.
What a BS? A good pre am is crucial in a good sounding system. Or go head to listen to your radio
LOL!!! Why add something else to the signal path if the input sensitivity of the amp is high enough?