Loxjie P20 Balanced 6N3 Tube Hybrid Amp for under $100


#102

I am not. I am not. I am not going to start building any kits again. And I am not going to get and have no interest in cheap IEMs. These threads are wicked and dangerous.

Besides, I have made a solemn vow. John Barleycorn must die… oops not that solemn vow. If I ever decide to build another kit it’s one of these.

http://triodeelectronics.com/st70buildkit.html

or maybe two of these

and one of these

https://www.erhard-audio.com/PAS-NGT.html

I am not. I am not. I am not.


#103

We need a diy amp/DAC discussion thread. Lol

With pretty shiny pictures.


#104

Hahah, absolutely feel you :laughing:

Have already a Tubelab SimpleSE to finish!


#105

Original Shuguangs back in…

Amazed at the SQ of the SRC2496/Loxjie P20/HD6xx combo. For anyone starting the hobby, is the rig I’d advise to jump straight from the beggining if DIY and modding isn’t your thing.

I cannot come with a cheaper rig sounding better… (you still need a SPDIF out DAC, as the SRC2496 doesn’t have USB-in).

I listen to a wide array of Rock/Pop/R&B/Funk/Punk/Reggae/Flamenco/Latin & fusion of subgenres.

Kind of rediscovered/found 80’s mastered pop music really enjoyable with the HD6XX+Loxjie P20 combo. Sincerely, I was surprised at the mastering/EQ of these albums, something which I haven’t found before (started my music library in 1995).

Similar goes to Motown: I was blasted to hear closer resemblance to on-stage experience: percussion, bass, gained a depth and detail clarity, an organicity I have only experienced either on studio or live. Upright bass sounds like… upright bass. With all the attack details, slides and changes in plucking, just as if I were hearing it IRL.

Each time I go back to some albums or songs, I’m surprised to find details I’ve never heard before, e.g.

  • Beatles Blackbird. Metronome always sounded like tik-tik-tik. Now it’s obvious is a tic-toc tic-toc… and not a metronome.

  • Elvis. Lovely upright bass and layering (Suspicious Minds). I never had noticed the (Hammond?) organ before, not the notes at least.

This is something very noticeable: synths, organs get their own, defined “layer” without losing textures or mudding up chords. Same goes for sax, which retains its texture (She’s Not You).

Percussion sounds really organic and detailed, you feel the pulse, and the timbre of each, with attack and decay almost intact.

In summary: lots of songs that sounded from flat, unispiring to plain unlistenable (gritty highs) I couldn’t bear, suddenly become enjoyable, and even some reveal as gems.

This, while keeping detail… was shocked to actually catch the two latest verses of Sexual Healing :laughing:


#106

I’d give a try at OTL! sound is really different.

Not better, just different. I usually listen to the Loxjie P20 during the day, then switch to the DarkVoice for relaxed listening at night.

Main difference: you’d never fatigue. Works wonders with so-so sources, shines specially in engagement.

DarkVoice is a good and cheap option, just look for a 7N7 to 6SN7 adapter and get Sylvania 7N7 JAN, incredible combo.

This amp matches better to mid-high impedance headphones (>=300 Ohm) wouldn’t bother trying anything less.

I’m puzzled though, people report it getting really hot, which is not the case with my EU version, I suspect 120VAC version may be different, will be opening it for some measurements of bias and voltages…

For anyone not wanting to mod, all you need to add is a 7N7 with its adapter.

Do the “shake” test when you receive it though, to check for loose parts; mine had a piece of trim inside.


#107

I decided to order up the parts, PCB and NuTube to build a pair of these (“never order the parts to build one of anything, if you can have two for twice the price …”).

I like the idea that it can be used as a headphone amp, as well as a tube-buffer (that’s always fun - if you’ve never had one, and have never had a tube or tube/hybrid amp it’s worth checking out).

Going to build them both “stock” to begin with, and make component tweaks later if warranted. And if they’re any good (Pete’s stuff usually is quite lovely) I can see this inspiring some interesting feature additions to another project I have in mind.


#108

Great! :smile:

My two cents:

Caps
Only mod from stock BOM I’d change straight away is upgrading from 505-MKS2.1/63/10 8 to 505-MKP2D031001F00KF

You can tweak with bigger bypass caps afterwards by soldering on the underside of the PCB, most significant positions being C4,C7 and C20,C21.

Volume Pot
Bear in mind replacing the pot once soldered to the PCB is a no-no… I’d go straight to the TKD if you’re going to case it as “stock”. (stock BOM pot control knob won’t fit in this case, you’ll need a 6mm round shaft one)

Stepped attenuators (or pots with detents) are a no-no with this amp, any sharp vibrations on the PCB will make the NuTube ring.

Microphonics/Vibration Isolation
Though some seem to have had issues with the NuTube microphonics, it hasn’t been my case; I just hear a distant zingggg for about 1 second at power on (induced by the power switch vibration). Completely normal and absolutely acceptable.

If going with alternate casing with power switch and stepped att/pot, connectors etc decoupled from the PCB, this could be alleviated by using rubber or silicon grommets sandwiching the PCB at its fixing holes.

Couldn’t harm, specially if you plan to use it as preamp, where vibrations can be induced by the speakers.

Grounding mod
I would also ground the pot case to a PCB GND pad, easily done with a e.g. cap leg trim caught between the pot shaft shim/nut, soldered to a free GND pad (as PCB has two different pot footprints you always have one free: easy peasy).

PSU
24V PSUs are really common for PoE and Telco routers (mikrotik); if you happen to have any friend or relatives working in telco, (W)ISP or network center, ask first… as when using PoE switches/panels you end up with a pile of unused and very fine 24V/2,5A adapters.

eBay should have tons of them too, just search 24HPOW. (They go for around $18 new)

I liked this amp so much I plan to build several more to give as gifts to relatives!


#109

Colour me confused and going blind from reading this thread on a phone!

I’m very interested in the Loxgie P20 tube amp to stick my toes in some warm tube water (so to speak). But there are some seriously flawed/conflicting reviews out in the wild.
In the specs I noticed a huge difference in output beteeen bal/unbal outputs. I reallize a difference is always the case but 6x more Mw?

From the spec page:

“Loxgie tube hybrid amp:
300Ω: 55mW
300Ω: 325mW”

Next, there’s a revue on the Amazon link provided (4 star review) where a reviewer begins with…

“I’ll keep this short, simple and to the point.”

While keeping it “short, simple”…etc. the reviewer proceeds to write a tome praising the amp but knocking the volume as low on inefficient headphones (while neglecting to indicate if he’s running the amp balanced or SE) :roll_eyes:

It seems this piece of gear was intended specifically for use in balanced mode, with SE thrown in for convenience. I don’t mind if that’s the case as I have a decent balanced headphone set up but would just like to know if the P20 could push the HD580s in SE? I don’t really like swapping the custom balanced cable too often from the HD650s as those ear-cuo connectors aren’t the most robust.

I suppose at this price it’s no big deal but If anyone who owns one could chime in with an opinion on this, I certainly trust the guys here more than reviews on Amazon.

Thanks for any comments beforehand.


#110

I read that same “review”, but IMHO brings little. (BTW, it’s Loxjie P20, not P30)

Yes, truly balanced amps do 6x more power in balanced mode vs SE.

This amp is worth if you use a balanced source, and balanced headphones, otherwise sound is… meh. I think that’s the reason behing the different reviews.

Regarding heaphones, HD6XX really shines with this amp.

I send source at 0dB, volume setting on the P20 between -30 and -24 most times depending on source level.

Whole range being -60-0dB, so you sit right in the middle of the volume: it’s obvious the designer target was fully balanced chain.

For $99, really difficult to go wrong, including the nice touch of relay-based mute/source/output selection and balanced electronic volume pot with 1dB precision.

what headphones will you be using with it?


#111

Thanks for the reply. I didn’t see it it as I was editing the post for typos (obsessively;) as I’m tired of seeing my posts with 100 spelling errors.

I do have a balanced LD MKVII+ but don’t think the swing is 6X between bal/unbal but I’d need to recheck the spec sheet to be certain.

(As you might have noticed by now, I’m using Senn 650s and 58X).

Damn, I’ll get one error free post from an iPhone even if it kills me!


#112

Hahah, compulsive editing here too :laughing:

You’ll love the 650/58X with the P20.

I don’t really like swapping the custom balanced cable too often from the HD650s as tgose ear-cuo connectors aren’t the most robust.

I have been thinking on this too, don’t like abusing the headphone sockets. I believe I have spotted some custom cables having a detachable connector, anyone knows these? This way you only swap the cable portion from there up to the amp…


#113

Do you mean the dongles that attach to the ear-cups that you then attach your headphone cable to?

If so, I haven’t tried them because I doubt I’d like the added weight and it adds another connection (placebo or not :wink:
I’d rather just use my portable Arrow amp/dac for SE as it likely sounds better than the P20 in SE based on your comment (along with what else I’ve read).

Thanks again, I’ll likely snag one soon in case they decide to up the price (again).

I’m really going to have to start using my PC for these comments, as I just can’t type efficiently on a bloody phone!


#114

Do you mean the dongles that attach to the ear-cups that you then attach your headphone cable to?

Yes…

Same thoughts here… have a couple cup plugs coming, will experiment with MMCX or similar connectors on a custom cable.


#115

Cool, thanks for experimenting. Please post your results when you get around to checking them out.

So you make your own cables/adapters?


#116

P20 needs barely any of it’s volume to power the 58X. I found the bass to be a bit too much for my liking though. But personal preference of course.

I use less than half the volume capability on balance to drive the HE560 planar.


#117

Thanks for that antdroid,
I’m assuming you’re speaking of balanced mode, which even by the spec sheet, one can pretty much tell would likely drive the 58X fine.

I was mostly asking about the single ended SQ/VOLUME as my best balanced cable is a solid silver version as it pairs nicely with the 650s (for which it was purchased).

But I also have a(n) SE Cardas cable that’s better with the 58X which I bought for HD600s that I regretably sold when things were a bit tight years ago. Low exchange on CAD $ (and two other pair of Senn cans) kinda make buying another HD600 a low priority atm.

Long way of saying I’m hoping for decent SE output as my main amp is balanced with less than optimal SE output. Little Dot also put most of the tech into getting a good balanced output into their MKVII solid state amp.

For 100 it's not a big deal and I'd get some tube warnth but I'm in that "should I get another kinda decent amp or start over looking for something better for more that covers both SE and BAL well enough" place :tipping_hand_man:.

There don’t seem to be many designed to perform well with both so I might just look for a decent SE tube amp or buy the P20 just to hear the thing!


#118

There’s a US seller on reddit /r/avexchange that’s selling a P20 used with three pairs of tubes. One of the pairs, alone sells for more than $150, which is his asking price for the whole set. The others are the GE JANs which are ~ $15-25 for a pair, depending if you buy matched or individual unmatched. Not a bad deal. It’s more than the new price but you do get some rare expensive tubes in the deal.

If I have some time, I’ll test the SE later with HD58X


#119

If you don’t want to make your own, here is a xlr to stereo 1/4 adapter. I have it and use it.


#120

I bought this one: https://www.amazon.com/gp/product/B07D7LG5BL

The first one I got, not sure if it was the same you linked to, wasn’t soldered correctly, and I didn’t want to redo it myself, so I just got the one from New Fantasia, which makes good cheap cables.


#121

I’m using my Massdrop THX AAA 789 for general neutral balanced and SE headphones. Was $349 and will likely sell fast next drop due to many great reviews.