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Old 17th December 2011, 10:44 PM   #1
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Default Audioromy FU-29, Latest Model 828A Mini Review

I received my Audioromy FU-29 Model 828A amplifier direct from China via UPS Express saver in just two days this past week. Total cost was ~420 USD including shipping and insurance. Not so much as a ding on the box! The toobes were all wrapped in bubble wrap under the toobe cage and there was no damage at all sustained.

Got the amp out of it's well packed box and installed the tubes. Any of you that get one of these do not try to peel off the tube position identification stickers they put on. Just wait till the toobes are warm... mine literally fell off the 829's after they came up to temperature. And they are easy to peel off a warm toobe.

My amp worked at first power up just fine and has continued to work just fine. There is a slight crackling in the right channel... because of a flakey input stage toobe that clears up after a few minute warm up and I'll need to aquire some better input and driver toobes. I already aquired a set of JAN RCA 829B NOS toobes for when the Chineese FU-29's fail. 829's are very inexpensive toobes! Even brand new Cetron 829B's sell for ~30 USD each. There is some question about what toobes are actually in this version of the amplifier vs. the earlier model that according to the specs used 6N1's & 6N2's. I can only read one of the toobes labeling. Seems that the seller (Tubestein) took considerable time to polish up everything on this amplifier before sending it out... including polishing the numbers almost completely off the small toobes. I can make out a 6N3 on one of the driver toobes so this amp is clearly different than it's earlier version. The main power supply board also lacks the relay that some seemed to say was a constant failure point. The output transformers have also seen a revision and they way they are mounted on the rear of the chassis is different. The power transformer is now centered at the rear with an output transformer on each side of it. This is an integrated amplifier folks... input select is novel... a DC controled DIP relay which is located right at the input jacks does the input selection. The level pot is a 10 cent pot so this will probably be my first mod. Unfortunately a NOBEL pot that I had in my parts stash is too deep to fit so I'll have to explore other options there but the 10 cent pot has to go! The amplifier is not really large but weighs a hefty 40 pounds or for you foreigners... thats 18.2 kg.

How does it sound? Very detailed, lots of depth, excellent imaging and sound stage, decent bottom end punch... this is ONLY 30 watts after all... Vocals are crystal clear but not overly warm... in all this dosn't sound like your typical warm tubey sounding amplifier, it sounds literally amazing. It drives my 6 ohm Dynaudio Audience 9's to decent levels and it is a very amazing little amplifier. I don't know of a USA built amplifier that uses 829B's but if there was one it would probably easily cost ten times this one's price. All in all this amp beats the pants off any of the 5 or 6 Dynaco Stereo 70 amps I've owned over the years including the Curcio modded ST-70 and the Audio Research modded ST-70. It would still be a bargain at twice it's price!

Mark

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Not sure why the photos are not working... Here is the url to the set of photos on my flickr site:
FU-29 - a set on Flickr

Last edited by Mark Allen; 17th December 2011 at 10:52 PM.
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Old 19th December 2011, 05:12 PM   #2
Mush is offline Mush  United States
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Thanks for the review. It makes me want to buy one.

I bought my Audioromy 845 by accident. It's been one of the best purchases I've ever made.
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Old 8th March 2012, 07:28 AM   #3
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hello,

i've just read your review and think the same. I've received mine on monday, with just one Fu29 out of order, the glass was broken on one anode pin. But while i was waiting for it (10 weeks for France!), i've had time to buy a couple of RCA 829B so it's now ok.
On this version, the input stage is 6N23 and 6N3 as phase shifter. As i have russians valves, i gonna replace them. But 6N3 is not a toobe that i really like, so what do you think to replace with a 6N6p ?
I'll try to put MKP capacitors in the power supply too and PIO on the signal.
If you have any experience, you can share !
nice day for all
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Old 27th June 2012, 03:02 AM   #4
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Just a quick update on my FU-29 amplifier... After many of hundreds of hours it is still performing beautifully. I pulled the Chineese output tubes at about 50 hours and put in a set of RCA 829 JAN tubes and rebiased it. I did loose one of the Chineese input stage tubes after a couple hundred hours. All small signal tubes have been replaced with matched pair Russian tubes. Anyway, having owned many expensive factory built amps plus having built a couple dozen types over the years the Audioromy FU-29 still stands at the front of the lot.

Mark
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Old 20th April 2014, 09:19 PM   #5
milosz is offline milosz  United States
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Default Audioromy FU29

I bought one of the original versions of this amp a few years back. I thought it might be good on my Quad ESL-57's and it was OK but not quite enough power. Also a little bass-heavy on the Quads due to interaction with the weird impedance curve of the Quads no doubt. I now use a Citation II on the Quads and am very satisfied with that.

ANYWAY I tried the FU-29 on a couple of other speakers I had laying around. I put on the little Polk RT25i's I had and - WOW! - what a difference over the various solid state amps I have. There was a "sheen" to the highs without being spitty or sibilant, and mids were warmed up a bit and quite rich. Bass wasn't as tight as solid state, but you know you don't get much bass out of a 5-inch two-way anyhow, if you want bass with these little speakers you're gonna have a subwoofer anyway. The little Audioromy FU29 and the Polk RT25i's had the most musical sound I EVER heard from a $600 system. Really a joy to hear. Accurate? Probably not. Euphonic? Yeah a bit, but not over-done, not swimming in "sweet tube sauce."

Now, this was the old original design. I didn't really have a place to use it so I sold it to a musician friend - with the little Polks - for $400 and he's used it as his main system for music and TV, in daily use since 2012. Two of the 6N1 tubes have gone on to join their honorable ancestors but these are like $5 each to replace so no big deal. The original Audioromy FU29 had plastic plate caps and these have crumbled, I put on ceramic ones. (I think the new design uses ceramic plate caps.) No other problems after a couple of years of use. He's since replaced the Polk RT25is' with PSB B1's and he reports they sound similarly good.

For people who claim that the Chinese amps are low quality, I would say that something that sounds this good and has been so reliable over a couple of years is not under any definition "low quality." Inexpensive, yes; lacking boutique parts, yes. Low quality- no.

I am buying a used "828A" version that some US owner is offering for sale, I have a pair of small 2-ways in my life these days that I want to sound like music and not like clinical instruments. (Seas Millennium tweeter, Seas Excel 5 inch in a sealed box, fairly straightforward crossover designed for me by Selah Audio)

Below is what I think is the schematic for this amp, I **THINK** this is the 828A version. As you cans see the FU29/829 is a beam power tube, two "tubes" per envelope, they are run push-pull. HOWEVER the beamforming grid is NOT run "ultralinear" fashion tapped off the output transformer, but just fed a straight DC voltage. "Pure tetrode" type output stage. There thus appears to be NO overall negative feedback. The amp appears to be run in Class A and so the inherent overall linearity is good, permitting a zero feedback design to produce acceptable levels of power without distorting like a fuzz-tone effects pedal.

This low or no feedback design is somewhat the fashion for amplification these days. Engineering wise one can argue this design decision. When fed a sine tone signal, adding negative feedback greatly lowers the distortion from an amplifier, generally allowing a higher amount of power to be got before objectionable levels of grunge comes in to the signal. Also, output impedance of tube amps is usefully lowered with the addition of overall negative feedback, meaning less Ohm's-law interaction with the frequency / impedance curve of the speakers being used. However music is NOT a steady-state sine tone, and some folks say that negative feedback can be heard and does harm to the MUSIC. I don't know about that theory- it's true that music is not a sine tone, but ANY waveform is identical to a complex combination of pure sine tones that changes over time, and that the "lag" of negative feedback is far less than the period of even the highest frequency component of this signal. So, OK, I think that negative feedback is not the "music killer" that some fear it is. BUT-

BUT, a tube amp without overall negative feedback is going to have a higher output stage source impedance and thus interact more strongly with the speaker's impedance, and I think that this is where the "magic" of the FU-29 comes in. (Higher amp output impedance also means lower damping factor, thus bass will usually not be as tight.) The interaction with the speaker is more than just a complex and gentle EQ curve, however- tube amps have a different harmonic "flavor" to the distortion that they introduce - all amplifiers introduce some distortion of course- and I think the slight harmonic "tube sweetener" along with the interaction with the speaker's impedance curve gives the FU29 a special sound on certain speakers, desirable for listening to music (but maybe not for monitoring a recording mastering session.) I think one would do well to audition several speakers on this amp if possible, and I think you'll find some to really "wake up" musically with this amp. I would expect that full range panel (Magnepan or electrostatics etc) speakers, full range single-driver speakers and other speakers with "straightforward" impedance curves would not be good candidates for symbiosis with this amp.

The FU29 also LOOKS COOL. The 829 is a rather exotic looking tube.

It was originally designed for radar keyer circuits. One or two ham radio rigs have used them over the years, but no other commercial audio amp as far as I know. There's a tone of NOS ones out there, as well as current production. THEY ARE INEXPENSIVE TUBES!!!! That's great. I HATE spending money on expensive tubes!

SO- THREE CHEERS FOR THE AUDIOROMY FU-29! A fun little amp!

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