Audioromy 838A FU13

[Pavlov]

Ok I've been swapping some tubes without any result.:sigh:

First I tried the power tubes, the problem stayed at the same channel so it's definitely not a faulty fu13.

I did the same with the pre-amp tubes, and again nothing changed.

At the moment I'm hoping it's the rectifier tube, but is this likely? I guess it's possible something goes wrong when it rectifies alternating currents, but is it possible it'd cause one power tube not to power up?
edit: => Ok I've eliminated the rectifier tube as the source:thumbsdn:

=> None of the tubes are the source.

I've opened it up, I'm no technician but everything really seems to be ok, no burn marks, the soldering is as it should be I guess. Can someone take a look at the pictures?

Can it be a problem with the transformers perhaps? I don't see a obvious way to open the top...
:tears:

 

[EWSintheUSA]

Uh, I'm sure you swapped your input cables and your speakers to verify that the problem is indeed inside the amp -- yes?

 

[Pavlov]

Yes, I tried that. But the power tube doesn't even light up...

 

[EWSintheUSA]

Definitely not the problem, but your 838A input cables (grey, visible in the "whole bottom" photo you posted) are apparently touching the choke coil (the big transformer-looking box).

I believe the input cables on my 838A are run neatly along the sidewall of the housing. A careful builder would not allow those cables to touch the coil; it *could* cause hum. Well, those input cables are shielded, so in the worst case I'd think it would be a very small hum...

Perhaps those wires, or other wires, have moved from their original positions. Could one be broken?

 

[EWSintheUSA]

If the problem is in only one channel, then there is nothing wrong with the rectifier (power) tube. That power tube serves both channels.

 

[Pavlov]

Definitely not the problem, but your 838A input cables (grey, visible in the "whole bottom" photo you posted) are apparently touching the choke coil (the big transformer-looking box).

I believe the input cables on my 838A are run neatly along the sidewall of the housing. A careful builder would not allow those cables to touch the coil; it *could* cause hum. Well, those input cables are shielded, so in the worst case I'd think it would be a very small hum...

Perhaps those wires, or other wires, have moved from their original positions. Could one be broken?

Well I noticed that fault already and dealt with it.
I carefully checked all the other wires and followed them through and I think the builder did a fine job on the wiring (tough he did something wrong:sigh also the soldering looks decent.

Can you tell me btw how to open up the case behind the tubes? I'm starting to thinks it's caused by the transfo's...

If the problem is in only one channel, then there is nothing wrong with the rectifier (power) tube. That power tube serves both channels.

I thought so...

 

[Pavlov]

Thank you EWSintheUSA for the troubleshooting so far, and finally I have found a problem we can work one, I'm getting optimistic again :yes:.

I can't tell how, but I managed to miss something that is definitely burned, as you can see in the picture.

Is this a sign of something bigger going on and what the heck is the function of that?

Btw, can someone tell me what the brown gunk is on the picture?

Thanks!

 

[EWSintheUSA]

maybe the brown stuff is OK...

There are a few pics of this part of the board on the web. Two of those resistors are monitored when adjusting bias, so that's why that area gets attention.

I notice that several of those web photos show tan or brown "gunk" there. It is not unique to yours. I get the impression that it is some kind of cement, or perhaps residue from soldering resin.

Because it is on resistors which are in both channels, it may well not be related to the problem. I would not think it is the problem -- I see no burn marks on the circuit board, and the resistors themselves do not appear to be charred.

As for opening up the transformer compartment, I've not done that. Before doing that, it may be good to probe around with an oscilloscope and compare the signals you see on the two channels. (Of course, with this amp, quite high voltages are present, so if you are not experienced with such procedures, methinks this is *not* a good time or place to learn.)

One more question; what speakers were connected when the channel failed? Low impedance? Plain old eight ohm? If you don't know the speakers' impedance, maybe you can tell the make & model.

 

[EWSintheUSA]

Wait -- Oh yes.

Now I see the definite burn mark on the board. (My glasses...) Where the wire jumper is, to the right side in your posted photo.

Yes that is related to the issue; it is bad. More later...

 

[EWSintheUSA]

Pavlov,

About your recently posted photo (IMG_1874). There is a blue capacitor next to the burn mark on the board. The top of the cap is not clearly shown in the image. The cap is *supposed* to be wrapped with blue plastic insulation. Is the white spot I see on the top of the cap a reflection, or is some of the plastic missing / scraped away?

Could that part of the cap have touched the cover plate of the chassis? Is there a correspondig mark on the chassis cover?

 

[EWSintheUSA]

Lastly, the dent you reported when you first received the amp -- the burn on the board is on the same side as that dent -- yes?

 

[Pavlov]

One more question; what speakers were connected when the channel failed? Low impedance? Plain old eight ohm? If you don't know the speakers' impedance, maybe you can tell the make & model.

8 ohm speakers where attached to the 8 ohm output, no issue there I believe:scratch2:

Lastly, the dent you reported when you first received the amp -- the burn on the board is on the same side as that dent -- yes?

No, that happened at the complete other side of the amp

About your recently posted photo (IMG_1874). There is a blue capacitor next to the burn mark on the board. The top of the cap is not clearly shown in the image. The cap is *supposed* to be wrapped with blue plastic insulation. Is the white spot I see on the top of the cap a reflection, or is some of the plastic missing / scraped away?

Could that part of the cap have touched the cover plate of the chassis? Is there a correspondig mark on the chassis cover?

No I don't think there's a problem with that capacitor, it looks as it was when I bought it.


I don't think I'll be able to swing it on my own so I contacted a tech in my area. (he's coming over saturday:thmbsp
I also contacted the seller (via ebay) who was very kind and sended thethe pictures to the factory, so hopefully they can help me :thmbsp:.

I'm hoping there won't be a big hassle

 

[myu701]

These Chinese tube amps seem to be more of a headache than they are worth. Hearing of all these troubles has really scared me off. Also, why would you suppose that the equivalent looking Audioromy amp available on eBay is now the "828"... What happened to the 838A? I suspect older inventory being dumped. The 828 has a rather ugly black cage, unlike the nice silver "birdcage" design of the 838A.

Regardless, I hope you guys get your problems worked out and many years of fine use (though at the rate things have gone, I wouldn't be surprised if the several Audioromy threads continue onward with troubleshooting banter for quite some time).

 

[EWSintheUSA]

Audioromy 828 output tube different, but yeah...

I've seen the 828 for a few years; it uses a different (ok, very "different") output tube. I'm not sure it is a case of dumping old stock; rather, it's a competing design (vis a vis the 838A).

I do see that that bay place has no 838As listed today -- OK, that is a little curious. Could the 838A contain an amount of rare earths deemed excessive by extended Chinese rare-earth export constraints?

Actually my experiences with Chinese vendors -- on the whole, and with my Audioromy 838A -- has been negative. With regard to initial sales, shipping, build quality, spare parts, comminucation and documentation, it would appear that Chinese manufacturers and vendors are not on the same page as most AKers.

Many AKers have 30+ year old equipment in superb condition. Does anyone think that 30 years from now there will be an Audioromy appreciation and restoration group?

 

[Kenny Brant]

I started this thread and have had no big problems with this amp. I did have to change the rectifier tube because the original went bad. I also changed to 6V6 tubes but not because the original tubes were bad.

I run the amp on a 110 volt supply as that is what the amp is designed to run on. I also backed off the bias and it makes the amp run cooler. Yes the bass sounds softer and the amp is a little less crisp in sound but I think the amp and especially the tubes will last longer.

Don't get me wrong, I don't think what I did has anything to do with the problems people are having with this amp.

I wonder if the parts and tubes are inferior as I have had Chinese car parts fail, the metal is just not as good as it should be.

I have a Doge 6 CD player, a Doge 8 preamp and the Audioromy 838A amp. I had the rectifier fail on the amp and the remote go bad on the Doge 6. I got the remote replaced under warranty but had to pay for shipping to Hong Kong to get it replaced but they paid shipping back to me.

This combination does not sound like a typical tube set up, it is not romantic or lush. It sounds more like a modern transistor set up.

Would I buy another set up like this again? Yes in a heartbeat. Could I have problems with them if I bought them again, probably.

I have a dbx BX-3 amp I was running with Pioneer HPM200 speakers. Thought I needed the 350 watts for the bass but I went back to the Audioromy 838A because even though I had a little less volume in the bass I think the bass sounds better, more natural and with more overtone or harmonics, plus the treble sounds more natural. The dbx is a fine amp I just like the 838A a little better.

I wonder if the problem is the tubes causing the failure, the new tubes are just not made as good as the old tubes are made.

The problems or failures give the amp and company a bad name which will take years if ever to recover. Reminds me of the new digital timers, last for a week then fail.

Kenny

 

[EWSintheUSA]

Tube rolling

Interesting. Yes, some bad tubes could cause a manufacturer to get a black eye, I suppose, but...

In general, I consider tube amps as advantageous for hobbyists to own because of the opportunity to quickly and easily swap-out output elements (tubes). It seems that for many tube components, there is a greater variety of tubes available as compared to transistors. Many/most tube equipment owners apparently swap-out tubes often; I seldom read about transistor rolling. There may be many reasons related to era of manufacture, reliability, production variation, availability, economics, etc, etc, etc, but I'll bet AKers exchange tubes and hoard tubes moreso than transistors.

With all of this tube rolling, the average "tube roller" has no doubt encountered bad matching, low emission, shorted or otherwise problematic tubes. It's part of the whole tube amp experience. It's something that experienced hobbyists and engineers, and AKers know happens. I myself have never discarded a piece of gear because of one bad tube (or one bad transistor, for that matter).

In my opinion, the complete lack of interest in :thmbsp: customer relationship :thmbsp: is what hurts Audioromy. Does Audioromy have a web site with schematics, operating and adjustment instructions? Customer blogs? Known problems? Does any sales department maintain a list of owners? Did you receive instructions printed in English with your $100+++ unit? Does Audioromy have a north America rep? Which Audioromy owners received phone calls to verify that their new purchases were up and running?

No, Audioromy does not offer this kind of customer relationship. It is only through the kindness and wisdom of a few owners/hobbyists (Kenny tops the list; some Europeans have sites/posts that are helpful, too) that I have gleaned enough info to make my 838A operable, tolerable, and at times, pleasing.

But I do not think bad tubes are a significant source of the Audioromy fussing.

 

[myu701]

Interesting point about the power. The guy from Australia ran into power issues, as he was running on 240v and the amp is rated for 220v. I guess they weren't really targeting the USA, if the other selectable voltage is 110v. And running it on 120v would account for extra heat and perhaps some components not lasting very long. If only they provided a 120v option, or at least a circuitry design that wouldn't be hard to convert from 110v to 120v.

 

[Kenny Brant]

It just seems if a tube is not manufactured correctly (ie weak metal or out of tolerance for cathode, grid or plate distance) it will have an effect on the circuit. Even if the tube seems to run fine and does not go bad. That is something that should be able to be measured. But like is said who has a schematic to even tell if something is out of whack. Plus who knows how on the edge design wise are these amps. They may be on the ragged edge of stability. But instead of oscillating they burn out parts.

In the 60s voltage was much lower and the old tube equipment was meant to run on that voltage and not today's voltage, but the equipment back then was more robust then today's equipment. I think that is why a person can run the old amps that are out of tolerance with bad capacitors and resistors and not have a lot of problems with them. They are very distorted but the ear doesn't detect it so much. That is why a lot of old gear sounds lush and romantic. Rebuild an old Fisher 400 receiver and it sounds crisp and clear, but not rebuilt it sounds thick, lush and romantic.

And the Audioromy runs a high voltage for the FU13 tube. That has got to be hard on the components in the circuit. Plus if Audioromy is using low grade resistors and capacitors it is a case for suicide for the amp. That is why I cranked everything down as soon as I could. Man when those FU13's are running full tilt bias and voltage you can light up the room, that can't be good.

As much as I like this amp I am leery of it and keep it as conservative as possible. I don't trust the amp but that doesn't keep me from liking it. It's just the demon in me to see how long it runs before it self destructs.

I run the Doge's and the Audioromy on 110 volts because they all are Chinese made.

But you have to admit when playing a good piece of music it can sound really good. Even on the old 50's and 60's music I listen to a lot it brings out details in the music that is hard to forget, just the texture of the music. Then when you put a new piece of music on it is hard to concentrate on the music because the bass and treble distracts your concentration.

I still say it is a fine amp for the money.

Old Elvis or Zombies anyone, oh boy!

 

[Pavlov]

The high voltage is indeed hard on the components, my amp was luckily easily fixed by a VERY friendly local tech, who said the design makes it very hard to repare anything on the circuit board...
Kenny Brant, what is your bias setting?

Btw, can anyone tell me if i can roll the ecc88's with e88c's? It are not e88cc's! I have searched online but some say they are identical, some say they aren't. I have NOS siemens goldpins and would like to try them...

 

[Kenny Brant]

I have mine set at 55ma as suggested by Koifarm. The transformers run cooler and supposedly the amp produces less distortion.

As I understand you can use a E88CC (6922) in place of a ECC88 (6DJ8), but you shouldn't use a ECC88 in place of a E88CC. A E88CC is rated at a higher voltage. E88CC (6922) is rated at 220 volts, ECC88 (6DJ8) is rated at 120 to 130 volts.