X-1 Class-A Tube Amplifier with 5Z4P*1, 6N9P*1, EL34-B*2

Ridiculously great value. I have breadboard tube amps I'm constantly changing so I can try new things and keep pushing the envelope of my system. I bought this amp as a sort of sanity check of my better efforts figuring i can return it if it's complete junk or put in the garage if it's passable. This amp has the mojo. I tore it apart a week after I got it and the construction is top notch. The transformers are all beefy. Way bigger than I was expecting from a little desktop amp hiding it's transformers under a cover. Get one before they disappear you won't regret it. I did ask the manufacturer for a schematic and what they sent me was a mess with no negative feedback which just won't work for a pentode see setup. Fortunately this amp does have enough nfb to increase damping to a workable level and the power supply is a little better than what their incorrect schematic shows. One negative I see is a 100uf cap - way over spec - right after the rectifier so time will tell how often it eats those tubes. But so far so good. It came with Chinese 5z3, psvane shuguang el34s, and a Russian 69p. I rolled some other power tubes and 6sl7s in there and can honestly say the included tubes hold their own. The amp is also dead quiet.2 month follow up:Swapped this out for a few weeks and then back in. Still a winner. My next breadboard is going to be a se pentode el34, 12ax7 front end with some Japanese 3.5k output transformers to see how it compares.After spending time rolling el34s I prefer electroharmonix el34 1st, stock psvane very close second, and amperex blackburn xf3 third if you can believe that. The eh tubes are a good all around el34, great bass (breaks the mold of bass shy single ended) and are one of the most inexpensive el34 to boot. Buy a pair if you own this you won't regret it. I don't have a lot of 6sl7 to pick from but the 80s Philips are way better than what this amp comes with. The stock 6sl7 is probably the weak and I find it a touch sibilant sometimes.4 month:I returned to the stick tubes as I am using my other tubes in another project. I put maybe 20 hours on it in 4 hour stretches. The amp has really mellowed nicely. The sibilance is gone at this point. I agree with another owners comments the stock tubes are great...they just take time to come into their own and sound very balanced now but still I have that magic. I'm tempted to get a quad of the psvane el34b for my st70 now.Six month:Still going strong. The stock psvane el34 tubes sound so good I ordered a quad for my dynaco st70 and they did not disappoint a bit and I'm running 70s amperex xf4 tubes in that which I'm now setting aside for rainy days and I'm not giving up anything. Amazing how far Chinese tubes have come since I got into tube amps in the late 90s. I'm considering getting another one to mod at this point. I've had it apart a few times now and it's a great platform for modding if you ditch the circuit board and go point to point as I intend. I'll post my mod notes once I get my second one and spend some time on it. I'll probably go triode (small room so I can get away with 1-2 watts), CCs on the plates of the 6sl7 and cathodes of the el34s. It should punch wayyyyyy over it's weight class. Anyone wanting to discuss this or tube HiFi in general feel free to email me: Dave dot unlimited at Gmail dot com. Be safe and most of all have fun!Follow-up October 2018My system has totally changed and this still holds up great. Jbl 4560 bass horns with 2220a 15" woofers, emilar ec175 compression drivers on Renkus heinz 500hz constant directivty horns.I'm running an active crossover through my pc. 950hz lr4 crossover. Peq's at about 275hz and 3100hz -7db to take the peaks out of the horns gives me in room flat response from 25hz to about 15khz within +/- 3db other than a 10db null around 150hz. This is really good performance and get this.... 10x10 room. Integration is great despite all the internet myths you need to be 10+ feet away for this to "work".1966 dynaco st70 with solid state rectifier and Russian 6p3se outputs runs the 4560s. Gemtune x1 drives the emilars. The bass cabs are probably 106db/1w in the mid ass and the emilars probably 110+.First off the Gemtune has a great noise floor. There's some hiss I can barely hear with no music from my chair about 9 ft. Away which is better than a *lot* of other amps I've tried with the hf. There's something about se Pentode top end that just works. Crisp but never harsh. These continue to go strong with no issues. I probably put about 15 hours on a week. I had one issue where I'd get some noise if I nudged one of the el34 tubes but a quick, very slight tightening of the pins of that socket fixed it right up. These are pretty junk sockets but the good news is they are easier to tighten than the cup type sockets.I'm intrigued by the new $180 spud Amp Gemtune now offers, but this is a solid choice. Yeah you can find better amps for $200 but they will need some degree of refurb. This is simply the best option for a budget plugand play tube Amp.I've had some folks email me with questions and seeking advice. Keep it coming I don't mind at all. I enjoy spreading the good word about this Amp and good audio in general. Peace and love.

Here's a review from a 62 y.o. music enthusiast and audiophile wanna be. I am a discriminating listener with a wide variety of musical tastes, but I'd hardly call myself a sophisticated audiophile. Since being blown away by a friend's Macintosh tube amp back in the day, I've always lusted for a HiFi Tube Amp and considered them to be the Holy Grail. But, alas, I have never wanted to spend $1000s on an amp, so Tube amps remained on my wish list. That is until the Chinese, God bless 'em, began selling ChiFi on Amazon. I've been loving my (recently serviced) NAD 3020 for over 30 years. However, I feel this classic amp has served its purpose and fulfilled its duties well. It was time to try something different.I received my amp a week ago and it's got about 20 hours on it now. The rectifier tube(on the far left) was not like the one pictured in the listing (it's a straight tube like the other three as opposed to the different shaped one in the listing), but that's not a big deal. My vinyl and CD's have long been gathering dust and I now exclusively stream Tidal HiFi via a Google Chromecast audio. I bypass the Chromecast's native DAC (which is actually pretty darn good) via a mini-Toslink and optical cable that feeds one of the two DACs I have: SMSL Sanscrit 6th 32 bit/192kHz or Parasound Zdac. My speakers are Martin Logan LX16's (which are wonderful) in a 2.1 configuration with a REL Strata III sub (KILLER sub BTW!!). This rig is in my bedroom and I listen at low to moderate levels (except when my wife and son are out...and then all bets are off). I'm sure you've read all the reviews like I obsessively did before pulling the trigger on the Gemtune. Well, from the moment the tubes starting glowing I knew I'd made a good decision to buy this bad boy. As you'd expect from the "tube sound", the amp sounds warm, open and airy with an excellent soundstage that is fairly "deep". Others have said that it's like the band or singer is in the room with you but I wouldn't go quite that far. The soundstage certainly exceeds the width of the speaker separation (on a well engineered recording) and has enough depth that you can imagine the drummer's position behind the rest of the players and the singer positioned out in front of the instruments. However, I don't hear a lot of forward projection past the plane of my speakers. Maybe it's a limitation of my speakers (doubt it) or the fact that I'm not using a $2000 DAC or playing vinyl. Plenty of smooth high midrange to high end sparkle, but not ice picky and absolutely no listening fatigue. None. The bass (through my subwoofer) is deep and "rich" but not boomy. Just the right amount of "punch" from bass drum kicks and really quite tight. Put on Steely Dan's Aja (outstanding production engineering and very dynamic sound) and each instrument has a lot of air around it (boy, I hate using snotty Audiophile terms) and I'm truly hearing nuances that were not as well defined with my beloved NAD. Jazz like Stan Getz/Charlie Byrd's Desafinado from the Jazz Samba album has a realism that is hard to describe. Just beautiful reproduction. Sarah Watkins' (of Nickel Creek) voice sounds creamy smooh and lush and the mandolin, guitar, and fiddle are extremely articulate and crisp. With my NAD, I always had to turn down the bass (from the stand up bass in the band) as it was a bit boomy. Not so with the Gemtune.However, all was not well in paradise. I started noticing a 60hz hum when no music was playing or in soft passages. I only keep the amp's volume at 12:00 and BTW, it's plenty loud with my 92db Martin Logans. Don't let anyone tell you that you require higher sensitivity speakers than that 'cause it just ain't so, at least in a fairly large bedrom or medium sized room. You're not going to blow the windows out, but it's plenty loud IMHO. Anyway, back to the hum. I read many reviews here that said the amp was dead quiet with no hum. I was not able to live with the hum as I often listen at low levels and it was too obvious. I contacted Gemini Doctor and they immediately responded with some suggestions on how to try and isolate the hum. Long story short, they told me to send it back and order another one, which I did. I don't know what some negative reviewers here were talking about when they said they never received any emails from Gemini Doctor following a complaint. I sent several emails over the course of a few days and they replied within hours every time. EXCELLENT CUSTOMER SERVICE. The hum is the only reason I didn't give the full 5 stars (and that will hopefully change when I get the new amp in a couple of days) but this amp is fantastic at this price. You know you want it...just buy one.

Although my Gemtune X1 sounded amazing when I first got it in August, it's now blown 2 fuses within just a few days. (We have nothing wrong with our electrical, as we've checked it out.) I emailed them regarding this issue nearly two weeks ago, and there has been ZERO response on this. Considering how much this cost, only getting a few months worth of use on it was EXREMELY disappointing. The initial sound was amazing, but I won't recommend this, due to the absolute lack of customer service. Have to leave a one-star rating because I can't leave zero.

there is a weird smell from the unit when on. had to return it because it was so bad. also, it isn't loud enough. it is really heavy, seems to be build well. not affected by ground loops, so there was no hum. it is bigger than i expected.

This was a nice amplifier for four months. It burned up some of the components on its circuit board and will not even light the tube filaments now. Genini Doctor has not even responded to my email asking for their help: I am out the money I spent, and am going back to a nice little solid state amp. UPDATE: It took a couple of months - but Gemini Doctor finally shipped me a replacement amp that required a new tube and reimbursed me the cost of the tube. My only worry is that there is no information as to WHY the first amp circuit board failed.