APPJ-PA0901A Mini Watt Tube Amplifier owners what do you think of it?

[Tim64]

I have had my APPJ-PA0901A for about three weeks and have really been enjoying it. The Tube Cube looks to be the same unit with tube upgrade options available. I am still running the stock Shuguang tubes and am thinking of replacing the 12ax7 with the JJ long plate 12ax7. I have to admit it sounds pretty good as is. I am running this with Polk R40 towers 90db efficiency 3/4 dome tweeter and twin 51/4" woofers. The amp has no problem driving these. I have a Onkyo C-7030 cdp and my old XP computer for streaming hooked into a Radio Shack switch box.
One problem is if you want to use a tuner it produces static from 103.1 and below so not recommended for tuners I suspect the switching power supply is to blame. Compared to my Sansui A-80 integrated it is much more detailed, I am hearing details that were being veiled by my Sansui. Bass is not bad at all if it's on the recording it will be reproduced but it is more polite. The Sansui delivers a more kick in the pants bass, but is it more accurate? not sure about this myself. To sum up I am going to be using this in place of the Sansui which in details it beats the pants off it. As far as loud my wife has already told me to turn it down a few times so no issue there. It will play louder than I ever would want to listen to music at. For the price it's a great value and my first experience with tubes so far I am enjoying the ride. I would love to hear from owners of these and there experience with tube rolling and anything else about these little amps.

 

[ZOOM]

Get some nice NOS European Ecc83 on there and avoid all the current stuff and you'll have a real nice amp.

 

[CZ4A]

I have the APPJ PA1502A headphone amp. If the circuit is similar between the 0901 and 1502 then you can improve the bass by replacing the 0.10uf coupling caps with higher capacitance Wima caps (0.22uf or 0.47uf). I've not had to do this yet since I've found some power tubes that boosted the bass pretty well but I have the caps on hand when I'm ready to try.

 

[Wildcat]

I have the TubeCube|7 myself (same amp) and it's nice, but not all that good sounding right out of the box. The highs are rolled off noticeably. This is acceptable (not good, but acceptable) in my desktop system but in my big rig where I ran it for a few hours, it gives everything a "dulled" sound, with a lot of detail lost. It wasn't until a few months after I bought it that I read a review of it, pretty much saying the same thing.

I suspect the craptastic no-name Chinese tubes that came with it are the cause but I can't really be sure. Point is, do I bother gambling $50+ on a set of tubes? I'm debating that now. (I may just buy the 12AX7 to start with, but I have a feeling all of the tubes in it are crap.) It is quiet, though--no hum or noise whatsoever. I don't believe the tubes are being driven all that hard, so tube life should be good.

I will also say that in my big rig, it had nowhere near enough power to drive any of the speakers I own, as it ran out of gas quickly when I pushed it to more than background music levels. (And mine were not inefficient speakers at the time--they were about 90dB/1w.) The EL84s are pushing out maybe 3 to 3.5 watts each, so they were unable to handle any orchestral crescendos, or anything with a lot of bass energy. This seems like a really nice amp for smaller systems (a desktop system, a den, etc.) but I would probably step up to something quite a bit larger for serious listening in my main system. I don't think they intended this to be a "giant killer," but it's kind of like a small dose of crack--you get a taste for tubes and then you crave more. In my desktop system, I run a small Dayton 6.5" sub underneath the desk; with some high-pass filters for the tube amp, maybe at 100Hz, that would help the system get more volume if I needed it.

I've used this thing for over a year and a half, sometimes several hours per day, and the only issue I've had is that one of the channels has dropped a decibel or two which again, could be the crap tubes. Otherwise it hasn't quit, hasn't gone up in smoke, etc. So durability-wise, it seems to be solid.

 

[Tim64]

I have a Tung Sol 12AX7 coming will give my impression if the sound changes.

 

[Wildcat]

I have a Tung Sol 12AX7 coming will give my impression if the sound changes.

I'm watching this thread, so I'll be waiting to hear what it sounds like.

I've been reading some of Uncle Kevvy's write-ups of the cheaper tubes at Upscale Audio. So I will likely make my own move based on his impressions of the tubes as well.

 

[ZOOM]

Again, an old European tube will fix it right up. Try Teleunken. This thing can deliver about 2 watts per channel, so you need very sensitive speakers.

 

[Tim64]

Again, an old European tube will fix it right up. Try Teleunken. This thing can deliver about 2 watts per channel, so you need very sensitive speakers.

I don't think the Telefunkens will drive the Polks they are only 90db 1w/1m. Currently the Shuguang tubes can drive them louder than I will be playing it at. Down the road I may roll in a couple Sovteks to see what they can do.

 

[Tim64]

I have the TubeCube|7 myself (same amp) and it's nice, but not all that good sounding right out of the box. The highs are rolled off noticeably. This is acceptable (not good, but acceptable) in my desktop system but in my big rig where I ran it for a few hours, it gives everything a "dulled" sound, with a lot of detail lost. It wasn't until a few months after I bought it that I read a review of it, pretty much saying the same thing.

I suspect the craptastic no-name Chinese tubes that came with it are the cause but I can't really be sure. Point is, do I bother gambling $50+ on a set of tubes? I'm debating that now. (I may just buy the 12AX7 to start with, but I have a feeling all of the tubes in it are crap.) It is quiet, though--no hum or noise whatsoever. I don't believe the tubes are being driven all that hard, so tube life should be good.

I will also say that in my big rig, it had nowhere near enough power to drive any of the speakers I own, as it ran out of gas quickly when I pushed it to more than background music levels. (And mine were not inefficient speakers at the time--they were about 90dB/1w.) The EL84s are pushing out maybe 3 to 3.5 watts each, so they were unable to handle any orchestral crescendos, or anything with a lot of bass energy. This seems like a really nice amp for smaller systems (a desktop system, a den, etc.) but I would probably step up to something quite a bit larger for serious listening in my main system. I don't think they intended this to be a "giant killer," but it's kind of like a small dose of crack--you get a taste for tubes and then you crave more. In my desktop system, I run a small Dayton 6.5" sub underneath the desk; with some high-pass filters for the tube amp, maybe at 100Hz, that would help the system get more volume if I needed it.

I've used this thing for over a year and a half, sometimes several hours per day, and the only issue I've had is that one of the channels has dropped a decibel or two which again, could be the crap tubes. Otherwise it hasn't quit, hasn't gone up in smoke, etc. So durability-wise, it seems to be solid.

Maybe I got lucky but it sounds good with the stock tubes I just want to see if I can kick it up a notch or two. No surprise if the tubes used have wide variations in quality.

 

[gmfgmfgmf1]

How similar is this to the APPJ-6f3?

Got one of these a few years ago on a lark - friend and I liked it so well we called and asked if they made anything else - at that time answer was no.

 

[Wildcat]

I found the TubeCube review--I wondered why mine had sounded so lifeless in the top octaves, and found this review a few months after I bought it. The frequency response graph pretty much jives with what my ears were telling me.

http://kenrockwell.com/audio/tubedepot/tubecube-7.htm

I'll probably get new tubes early next year--they have to be the weak link here. I already have a few choices in mind. Nothing expensive, as I'm not putting $200 of tubes into an amp I paid $160 for.

Maybe I got lucky but it sounds good with the stock tubes I just want to see if I can kick it up a notch or two.

Which Tung-Sol did you get? There are two 12AX7s, one being a gold pin variety that costs a bit more. (Upscale mentions it has more strength in the high frequencies, so that might help with my situation here. Keep in mind, too, that while it's the same basic amplifier, Tube Depot could be having the amp provided with tubes that they chose for their specific variation of this amp. APPJ may be doing something different in tubes. I should take a pic of my tubes later on and post them in here.

 

[Poultrygeist]

I've had the original APPJ/Miniwatt S1 since it was first introduced. Great little single ended amp if you have the right speakers. The stock Chinese tubes were crap.

 

[Poultrygeist]

APPJ has made five different models which include my S1 ( 4 tube ) , the N3 ( 3 tube ) , the 2 tube ( power supply on bottom ), the 4 tube ( power supply on bottom with same tube compliment as the S1 ) and the latest which is the PA1501A shown below. From all accounts the 1501A is the best of the bunch.

 

[Tim64]

Ok as promised the Tung Sol 12ax7 arrived yesterday and I have maybe four hours on it but it is a big improvement over the stock tube. I'm not going to go into great detail but my impression is better bass and the sound has a nice smooth sound now not as clinical as the stock tube but it did not lose any detail either. Quite happy with the upgrade it is just to bad the heaters are enclosed so it does not glow oh well. The next upgrade will be the output tubes but I will have to wait for Santa to bring those. Meanwhile I will just sit back and listen to some tunes. By the way has anyone up graded the fuse? I have heard there is some sonic benefit but I don't see how unless the stock one is of a high resistance. I have not removed it to look at it yet, may just put a BUSS fuse in its place.

 

[Wildcat]

Regardless of the version, they are quite a neat little package! I will freely admit I partially bought one for the "cool" factor, the small packaging and the looks. But in my use (desktop, through small bookshelf speakers in a nearfield arrangement), it works out great since the sound is so relaxed. With my "computer" speaker set from before, it would grate on me after an hour or so. This one, I can listen to all day long. Even with the substandard tubes. Knowing what I know now, I could count on the tubes needing an upgrade if I bought another.

 

[Wildcat]

Ok as promised the Tung Sol 12ax7 arrived yesterday and I have maybe four hours on it but it is a big improvement over the stock tube. I'm not going to go into great detail but my impression is better bass and the sound has a nice smooth sound now not as clinical as the stock tube but it did not lose any detail either.

Nice! Did you go with the gold pin version, or the standard? I may go that route myself to wake up the highs on this.

 

[Poultrygeist]

The PA1501A uses 6AD10 TV tubes ( vintage with no new versions available ) but that's fine as they're inexpensive and readily available.

The APPJ N3 uses a single 12ax7 signal tube and I'd definitely go vintage there. I have some JJ 12ax7( aka ECC83 ) gold pins and they're average at best and

surpassed by any number of vintage tubes such as Amperex, Telefunken, etc. As for as power tubes the JJ's are not for me. I had two new EL84's pop within a

few months of playing time. I understand some APPJ's came with Shuguang's which I'd take over many new replacement tubes. My S1 came with cheap

Chinese 6P1 and 6J1 which based on APPJ's own recommendation I replaced with Russian 6P1P-EV and Western Electric 403B respectively. Huge improvement!

Nothing wrong with buying used vintage signal tubes if they test well. Signal tubes can last a lifetime.

 

[Wildcat]

A pal of mine from another forum sells vintage tubes that he tests (he has at least one tester at his place, if I recall). He usually works more with small signal tubes rather than power tubes, but occasionally comes across a few. I may see what he has available.

Too bad my amp doesn't use a 6DJ8 or equivalent--I used to use one of those Musical Fidelity tube buffers, and I have three spare pairs of tubes from it, plus a single Amperex 7308 gold pin (which sells for north of $75). I likely will sell these off, along with the buffer, since my preamp uses M8080s and I wasn't all that excited about the buffer anyway.

 

[tubeampking]

Ok as promised the Tung Sol 12ax7 arrived yesterday and I have maybe four hours on it but it is a big improvement over the stock tube. I'm not going to go into great detail but my impression is better bass and the sound has a nice smooth sound now not as clinical as the stock tube but it did not lose any detail either. Quite happy with the upgrade it is just to bad the heaters are enclosed so it does not glow oh well. The next upgrade will be the output tubes but I will have to wait for Santa to bring those. Meanwhile I will just sit back and listen to some tunes. By the way has anyone up graded the fuse? I have heard there is some sonic benefit but I don't see how unless the stock one is of a high resistance. I have not removed it to look at it yet, may just put a BUSS fuse in its place.

Good news considering there are better current production choices then the TS. The Sovtek 12AX7LPS for one, the JJ ECC83S for another. May even help with your tuner issue. As far as better sonics from a different fuse....total horsehockey.... You could also try some old production tubes. Judging from your description, I'd think a Raytheon 12AX7 w/ shiny black plates could help the amp live up to it's potential.

 

[Tim64]

Good news considering there are better current production choices then the TS. The Sovtek 12AX7LPS for one, the JJ ECC83S for another. May even help with your tuner issue. As far as better sonics from a different fuse....total horsehockey.... You could also try some old production tubes. Judging from your description, I'd think a Raytheon 12AX7 w/ shiny black plates could help the amp live up to it's potential.

Agree on the fuse unless it is some high resistance pos it should deliver the current needed for the power supply.