APPJ PA0901 A (Miniwatt N3)

I posted this on DiyAudio Full Range forum, so please don't say I double posted, I just thought maybe someone else would be interested in this little amp and some different tubes in it that I tried.

I just bought a APPJ PA0901 A (Miniwatt N3) and have been running the BIB's with F120A's. Out of the box with the tubes that came with it the amp sounds good.

I started rolling tubes in it to see what I could come up with. I first changed out the 6bq5's (EL84's). Put in a pair of Sylvania Balwin black plates stamped 312-426. Sound was brighter than with 6N4 tubes that were in it from the factory. I have a quad of matched GE grey oval plate 188-5's coming but don't think they will sound any better than the Sylvania's.

I next started rolling 12ax7's into the amp. First was Telefunken smooth plates, sounds good and lush with good imaging, good vibrato, boomy bass, sound is like old tube sound.

Next Telefunken ribbed plates sounds good and lush with pinpoint imaging, good bass and treble, better bass than smoothplates.

Amperex bugle boys good airy sound, pinpoint imaging, good vibrato, voices sound a little dark more like old tube sound.

Mullard sound good but a little flat on voices, more laid back. can hear more distortion, didn't care for them. But not too bad.

Tungsram loud and clear and clean with less lushness, pinpoint imaging. sounds like good solid state transistors. Good bass.

Sylvania JAN 5751 sounds nice and clean with pinpoint imaging. Not as loud as 12ax7's but almost. Good vibrato, lush sound, a little boomy in the bass.

RCA 12AX7 tall black plates rectangle getter. Good balanced sound, pinpoint imaging. Bass not boomy, can hear different voice styles.

I could live with the factory tubes or any of the tubes for that matter but the best so far is the RCA tall black plate.

I didn't notice a lot of difference in the highs or treble of any of these tubes, may be because of the F120A rolls off the treble and if I had a tweeter could hear more differences.

Now these tubes with this amp with these speakers in these cabinets is what I heard, maybe tomorrow I would roll these tubes in and hear a completely different sound, I don't know. But for right now I like the RCA best. Next would be the Amperex Bugle boy, then the Sylvania 5751, then the Tungsram.

The little amp powered these speakers just fine in my small room. Probably would run out of steam in a bigger room just like the speakers would. But for a good sound in a small room they get the job done. And low level listening is really good, it doesn't have to be turned up to get all of the details like a lot of speakers do.

I have one of these on its way to me for use in my office. Thanks for the info on the tube rolling - great to know.

Curiously, what speakers are you using?

Good luck with yours. I let mine play for about four hours straight before tube rolling. I should of let it burn in longer but just couldn't resist changing the tubes out.

But the tubes that came with it are pretty fine sounding without any warts.

For the money it is a darn good little unit.

I figured I couldn't build one for the price of the APPJ.

I am using it on a pair of Fostex F120A 4.5 inch drivers in BIB (big is better) enclosures I build about a month ago. They are rated at 89db sensitivity. They sound really good with this amp. They get pretty loud, but we are talking about 4.5 inch speakers and 3.5 watts. But if you are putting it in an office I think you will enjoy listening to it at low volumes with the right speakers.

It must have a pretty good power supply as it goes quite low with authority.

I wanted to go to a single ended amp and extended range speakers with no crossover. The combination sounds good to me.

I also didn't want to spend a ton of money if this didn't work, but everything has come together nicely. I use a Doge 6 and Doge 8 Cd player and preamp.

I would of liked a DHT SE amp but that will have to wait awhile.

I've had mine for a month and love it. Bought off the bay, and it arrived from Taiwan in 5 days!

took it into work a few times and people like it's sound. Some had no idea what vacuum tubes are, aha.

Have done some tube rolling and found the Telefunken 12ax7s and Russian 6p14p-er combo was the best. Mullard 7189s are also sound nice.

I bought mine on a Thursday and received it the next Tuesday.

scottfan which Telefunkens do you use ribbed or smooth plates?

I bought this amp because 12AX7s and 6BQ5s can be rolled in it, as I understand the earlier APPJ amp you couldn't do this with.

All the tubes I put in it sounded good, it is just a matter of what a person likes.

I use Telefunken 12AX7 smooth plates in the phono section of my Doge 8 preamp.

This is a ballsy 3.5 watts.

I like the Telefunken smooth plate better but deciding on either would be splitting hairs. It's really best to have matched sections. The stock Shuguang tubes also sounded great, and the 12ax7 had perfectly matched sections, 1350/1350 tested on a Hickok 800.

Try any 7189 type over 6bq5/el84s once your happy with the 12ax7.

I can't wait to install this amp on my machine at work once the right speakers are found. Space is at a premium there which was the reason for it's purchase. I just can't go the SS boombox route like others.

It should be a nice little unit for the office. Mine is breaking in nicely.

I agree you need a matched per side 12AX7. The RCA is real close but not perfect. My tube tested 70.0 on one side and 70.5 on the other with my tube tester. All the tubes I tried were either matched on the money or real close.

7189s are nice and I agree the tubes it came with are nice, a smooth not bright sound.

scottfan said:

I like the Telefunken smooth plate better but deciding on either would be splitting hairs. It's really best to have matched sections. The stock Shuguang tubes also sounded great, and the 12ax7 had perfectly matched sections, 1350/1350 tested on a Hickok 800.

Try any 7189 type over 6bq5/el84s once your happy with the 12ax7.

I can't wait to install this amp on my machine at work once the right speakers are found. Space is at a premium there which was the reason for it's purchase. I just can't go the SS boombox route like others.

Click to expand...

Heh - I am in the exact place as you - want something better than the typical iPod dock for my office, something smooth and sweet at low volumes (and heck - something that looks cool too!) and my current obsession is tubes (just picked up a nice Scott 299B.)

I have also been looking for the right speaker. For example, last night I almost pulled the trigger on a pair of AR M1's on the bay. Also been looking for inexpensive PSB Alpha minis (or their other small bookshelf models), Paradigm Atoms (like these a lot), small Wharfedales, DIY (lots of options, but the full kits are a little pricey for my version of an office system - I dont have the skills to build cabs - or they are too big.) NHT Superzeroes, the passive front-port Audioengine model - that sort of thing. Basically, super small, relatively inexpensive speakers.

I have a set of ADS L300c's right now, that might be the ticket - I like these speakers a lot, so in lieu of finding the magical pair I am looking for at the right price - I think the ADS will be my solution.

I was just reading up on these yesterday - they sound like really interesting amps,
and I have a fairly efficient JBL 3way horn system I want to run with them ...
kind of a hand tweaked 4333 in an L200 cabinet, if you are familiar with them.

Anyway - has anyone got any real time on one of these amps -
I mean more than a month or two?

Thanks for any feedback you can share

N3 life and death

hjames said:

Anyway - has anyone got any real time on one of these amps -
I mean more than a month or two?

Thanks for any feedback you can share

Click to expand...

I picked up one in April 2010. It died June 2011. Well past any warrantee. Tubes still light but it is dead, dead, dead. Opened it up to see if I could do anything at all and really couldn't see anything. Very tight. Whatever it is that fried is in the solid state section. Had many hours on it and that may have been it's demise. Dunno. I loved the sound coming out of it when alive and for a desktop system it was perfect. I used a Grant Fidelity TubeDAC 0.9 as a preamp/DAC combo and it rocked! I am literally hours away from anyone with the skills to figure it out so...

Great thread, thanks!
I love my N3, it's easy to roll when you only need 3 tubes.
My favorite combination is an RCA 12AX7 and Telefunken EL84s.
Next up would be Telefunken smooth ECC83 and Rostok Tesla EL84s.
I power DCM TimeFrame 600s or DCM Timewindows.
—Hep

hjames said:

I was just reading up on these yesterday - they sound like really interesting amps,
and I have a fairly efficient JBL 3way horn system I want to run with them ...
kind of a hand tweaked 4333 in an L200 cabinet, if you are familiar with them.

Anyway - has anyone got any real time on one of these amps -
I mean more than a month or two?

Thanks for any feedback you can share

Click to expand...

I've owned my N3 since early '09, and have about a year on this unit. Operation has been flawless so far.

I use it to drive my 15" coxials (Hawthorne Audio). Their average sensitivity I believe is around 95db. The MiniWatt can drive them with authority . . . surprising really, since I am running them full range on an open baffle.

Although I've heard other tube gear on other systems, this is the only tube amp I've owned. But all in all, I'm quite happy with what this lil' amp can do!

Thanks to the op, I think after hearing some impressions here, I'll just stick with the stock tubes awhile longer :yes:. They do sound nice.

Bombbadil111 I have been looking at Hawthorne Audio speakers because I want to build a pair of open baffles. Good to hear the APPJ will power them.

Did you buy everything from Hawthorne, I mean like all the drivers and crossovers. I don't know much about Hawthorne's so just asking for a little help and information. Did you build your baffles from plans they had?

Thanks

Hey Kenny,

Yep, I bought all speaker components (drivers, crossovers) from Hawthorne.

I did it in stages tho. I first purchased the coaxials and put them on a very simple (i.e. a piece of plywood) and short baffle. You can see this first effort on my homepage.

The coaxs can make bass, and for some folks this is a permanent arrangement. However, after getting feedback on the Hawthorne forum, I decided, as most do, that the "Augies" would be added to the mix. Augie is short for augmentation woofer. Of course this necessitated building bigger baffles as well. So I did. Kept it simple. There really is no magic formula for this build. A couple things to keep in mind however. Baffles should be fairly narrow, say around 20" to 22" wide. The spacing above the top driver should not be the shortest dimension.

Also, the Augie is not as sensitive as the coaxs. And so, I purchased a used Crown PS-400 for them. This is a beefy solid state amp from the '80's. Now, I run two Augies, in stereo. The drivers are all 15", although 10" are also an option.

This info can be found on the speaker builders forum on the Hawthorne site. The folks there are very friendly, and as you'll see, very enthusiastic about Darrel's creations.

http://www.hawthorneaudio.com/forums/viewforum.php?f=2&sid=8d01c19e9929aae32b495a1bb9a58e30

Keep in mind: There are a myriad of drivers, methods, techniques, ways of building OB's. I chose, perhaps, the simplest of methods, and considering the total cost, am very happy with the results.

Whatever direction you go, good luck . . . and HAVE fun!!! The quest for great sound is part of the fun. :thmbsp:

Thanks for the information Bombbadil111. I've checked Hawthorne out a little, will dig into them a little deeper.

Nice report
I came close to getting a N3 about a half year ago, but a 2A3 amp came up locally and I jump on the deal - no regrets as I really like my 2A3 amp a lot.
Then recently, the thought of the N3 came up, but, and again, another tube amp showed up locally on CL. A K-12M with 11MS8 tubes, built & upgraded nicely, so I jump on the deal.
Oh well, maybe someday - but I really have a load of receivers & separates I need to get out of the way.

OK, my office system is complete and tested!



ADS L300c speakers, Miniwatt N3, iPod Classic 160GB. Steely Dan - Aja ripped via Max to Apple Lossless.

Sounds great! Had to turn it up quite a bit to sound loud enough in my fairly large dining room - this thing will be perfect for my office. Exactly what I was looking for - something to take the slight high frequency edge off of the L300c's, look cool , small formfactor, reasonably affordable.

Will do some critical listening soon, and curious to swap in one of my Telefunken 12ax7's from my Scott 299b. So far, I hear excellent resolution of detail, decent imaging - very silky smooth highs. If I had to come up with a criticism, the midbass to bass area is not exactly as pronounced as I might like - but I have to say these speakers probably aren't the easiest load for this amp and I currently have them well away from walls in a very large room - so probably best to pass judgement when I have them in my much smaller office.

And..ooooo.....glowing tubes!!!!

Im resurrecting this thread ! These amps still being sold like hot cakes on the 'bay. One piece of information I cannot find despite googling is how do you check bias on these little amps ? Cant see any bias points on top near the tubes ? Im a tube newbie so sorry if this question sounds a bit dumb !

Also, how does this amp deal with speakers, being only 3.5w power ? My current speakers are 88db B&W 601. Would I need higher sensitivity speakers, say something around 90-92db spec ?

Hoping someone can help.
Stephen

Mine is the original S1 which has a fixed bias. I would think the N3 is the same. With 3.5 watts the N3 works best with speakers 93 dbs and above.

First things first - what a beautiful setup you have there.

Secondly - what is fixed bias ? Does this mean you dont have to check or adjust bias on the tubes ? Sorry I am indeed king newbie.