Jump to content

Tubecube 7/APPJ PA0901A/Miniwatt 3.5w amp


chriswhotakesphotos

Recommended Posts

Behold, the Tube Depot Tubecube 7!

 

Tubecube7-3_4-1

 

And the APPJ PA0901A/Miniwatt!

61oeR8TadrL._SL1500_.jpg

This is one of those China-built wonders that has no clear origin, but appears under several brand names. I'd ordinarily be wary, but between being sold by Tube Depot and having an awful lot of good impressions available around the internet (and no counts of one bursting into flames,) I find it quite interesting. Even Klipsch has one! 

 

U-Turn Orbit Basic with Klipsch Speakers

(http://www.klipsch.com/blog/u-turn-audio-orbit-basic-turntable-review/)

 

In true "Shoot first, ask questions later" spirit (and possibly against good judgement,) I've ordered one of these second hand. Actually, that's not true. I've ordered a self-reputed updated version that has two tubes: https://www.amazon.com/Gemtune-APPJ-PA1501A-amplifier-6AD10/dp/B00X5ECQ4Q/ref=sr_1_9?ie=UTF8&qid=1470282830&sr=8-9

 

By the way, it's $180. What a world to live in where you can try tube sound so cheaply!

 

I'll certainly be back with impressions once it arrives, but while we're here, has anybody here heard it? What does a tube amp sound like when it runs out of juice? Do you need to wait for the tubes to warm before you listen, or can you listen while they warm? Will it blow up if I feed it from my Adcom direct-coupled preamp? Will it blow up anyway? 

Link to comment
Share on other sites

Twenty seconds is sufficient.  Nothing terrible will happen if you start playing music before the tube cathodes are up to temperature.  A preamp is likely to degrade the sound and can easily overload the input stage of the amp if you turn its volume control up too high; however, if you spin vinyl, you can use its phono stage in lieu of buying a designated phono preamp.  You will know if you push the amp too hard as the sound will become annoying.

 

Maynard

Link to comment
Share on other sites

Those little toys actually play at or slightly above their pay grade. They use a switching (digital) power supply with EL84's. A friend brought one over several moons ago when I owned Belles and Cornwalls. Like most things audio one can certainly do better, and worse.

Link to comment
Share on other sites

I listened to it a good bit over the weekend and I'm definitely impressed that you can have sound like that for $200!

 

It's no good with the KG 5.2s, I suspect that it has a much harder time pushing the 10" driver and passive than the horn. Those speakers sound pretty bright to me no matter what, but with the APPJ they were unlistenable. Haven't tested with the RP-280Fs yet, but it's a delight with the Heresy KP-201s. I've used it for jazz, big band, pop, and electronic so far, as well as video games, and it holds up quite well. I like processed music as a benchmark for smoothness, if I can listen to Psy or dubstep and not want to cover my ears, then something's being done right. (But as is always the case with Heresies, a subwoofer is much needed)

 

Build quality seems quite nice as well, I initially wondered if it would have suffered aesthetically to meet its price. Instead, it's quite presentable and looks really nice. I like how it looks and the thick metal enclosure is great. Volume knob and power switch feel good, too, and it's nice and heavy.

 

It really does raise the issue of good watts vs many watts, if you ask me. I haven't pushed it to massive levels yet, but I like to listen fairly loudly no matter what. So far, it seems to have plenty of juice for any of my ordinary listening, I haven't been any more conservative with levels than when I use my 60w Adcom. It's definitely interesting that I can enjoy similar levels with a seventeenth of the power!

 

It does like a preamp, I've determined. When I fed it the DAC, it reached distortion pretty fast. When I use an Adcom preamp, it's no problem. I do plan to try it with the RP-280F as well, but I'm expecting it to perform similarly to the KGs. It just seems like it takes more power to get big drivers to perform at 100%. But for any smaller speakers, or Heritage speakers, I can't imagine finding anything better for $200. There's plenty of time to come up with further impressions, but I'm really enjoying it so far!

Link to comment
Share on other sites

2 minutes ago, NOSValves said:

I'd imagine that amplifier has a pretty high output impedance and really struggles with speakers that dip low impedance wise. The heresy is about as easy to drive as one could imagine impedance wise...

That sounds about right to me. I may get the Tubecube with three tubes at some point in the future just to see how different it sounds, the two-tube PA1501A I have only has one red terminal for each speaker, while the Tubecube has terminals for 4, 6, and 8-ohms. Do you think that would make a big difference for the bigger speakers?

Link to comment
Share on other sites

Here's another question: Is it easy to replace 6AD10 tubes? It doesn't seem like there are many of them around, and everything I can find is new old stock or otherwise pretty nondescript.

 

Edit: Just saw NOSValves' second response. Bummer! Maybe I'll get the three-tube one later on, it seems like it uses much more common tubes.

Link to comment
Share on other sites

On 8/8/2016 at 11:28 AM, chriswhotakesphotos said:

It does like a preamp, I've determined. When I fed it the DAC, it reached distortion pretty fast. When I use an Adcom preamp, it's no problem.

When you fed the DAC directly into the amp did you have the amp's volume control up all the way, controlling the level with the DAC?  If so, I'd try it again with the output of the DAC set low enough to allow the amp's volume control to have a wide operating range before any distortion is noted.  I've never encountered a situation in which using a preamp sounded better, especially SS to tube, than a direct source to amp connection.

 

Also, the 6AD10 is a very nice tube and I seriously doubt that the EL84 version will give you any improvement.  Rolling different brands is also not likely to render any change in the amp's characteristics. 

 

Maynard

Link to comment
Share on other sites

13 minutes ago, tube fanatic said:

When you fed the DAC directly into the amp did you have the amp's volume control up all the way, controlling the level with the DAC?  If so, I'd try it again with the output of the DAC set low enough to allow the amp's volume control to have a wide operating range before any distortion is noted.  I've never encountered a situation in which using a preamp sounded better, especially SS to tube, than a direct source to amp connection.

 

Also, the 6AD10 is a very nice tube and I seriously doubt that the EL84 version will give you any improvement.  Rolling different brands is also not likely to render any change in the amp's characteristics. 

 

Maynard

 

Do you think it would be hard to find replacements when needed, though? Tubedepot and other sites carry them, but it seems like it's mostly new old stock, and I'd wonder if it would be tough to find them matched. Thanks for the information!

Link to comment
Share on other sites

The 6AD10 is only available as old stock (whether new or used) and is fairly inexpensive as you may have noted.  They should be around "forever" as they are certainly not a high demand tube.  But, if you are concerned, and plan to keep the amp, why not buy a pair to have as spares?  The chances are you will never need them (assuming that the designers of your amp are running them within spec).  There's absolutely no need to have matched tubes in your amp.  Normal production tolerances are close enough that any channel to channel differences will probably be inaudible.  A very reliable and honest vendor, whose prices are very competitive, is Jim Cross:

 

https://vacuumtubesinc.com/

 

Maynard

  • Like 2
Link to comment
Share on other sites

Those little Chinese amps are pretty nice. I have one or two myself. I wanted to experiment with them and had one totally rewired and had the caps and resistors upgraded and it made a difference. I did sell it after being made an offer I couldn't refuse, and then purchased another one, just wired in triode mode only. The amps seem to get better parts in them as they "upgrade" the models.

Link to comment
Share on other sites

2 hours ago, Jim said:

Those little Chinese amps are pretty nice. I have one or two myself. I wanted to experiment with them and had one totally rewired and had the caps and resistors upgraded and it made a difference. I did sell it after being made an offer I couldn't refuse, and then purchased another one, just wired in triode mode only. The amps seem to get better parts in them as they "upgrade" the models.

 

They say the one with 6AD10 tubes is supposed to be an updated version of the ones with three tubes, but I can't say what's actually been done differently. Either way, I'm enjoying it the more I listen to it. It seems like a tube watt is worth more than a solid state watt, I still haven't had to be much more conservative with levels than with my Adcom amp, and I had Exo on pretty loud last night. 

Link to comment
Share on other sites

Yes, they are.

 

There are a bunch of people on here who can help you if you ever get the need to upgrade to another amp, custom builds, or even taking that amp and upgrading the caps and resistors. Some may say not to as they are builders, but some will help point you in the right direction or offer to do it for you.

 

Where in NJ are you? I'm in Fords (Woodbridge). I'd be more than happy to let you preview how my amps sound if you ever wanted to check them out with yours. I have forte II's with the Crites crossovers and titanium tweeters as well as KG 4.2's with same upgrades minus the tweets that I use for my 2 channel stuff.

 

Maynard made a recommendation on speaker placement for me for my room and when I have it set up that way,the speakers just disappear.

Link to comment
Share on other sites

Here's my setup using that amp. I use it for my Mac Mini. It does great with a pair of Overnight Sensation speakers I built. A Carmody design. Great imaging with iTunes. Not my main system but sounds nice and it is fun to have the little tubes lit up on my desk!



43971ab3fa67f6bfc30fae62b1dc008a.jpg


Sent from my iPad using Tapatalk

  • Like 1
Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...