XDUOO TA-30

[Bow_Wazoo]

I recently became the owner of the Xduoo TA-30.

Without going into detail, I would just like to mention in advance that I am very satisfied with this device.

One thing, however, has made me wonder from the beginning.
According to the manufacturer, two ECC 82 tubes are used for amplification.
Which is quite unusual in itself, since these tubes are more likely to find their place in the preamplifier.
In addition, then comes the very high specification of the maximum power of 3W RMS (32Ohm load)

xDuoo TA-30 Tube Headphone Amplifier - xDuoo official store

Worldwide free shipping Fast delivery, usually 3-5 days arrive Shipping via DHL, TNT or Fedex Original new product Manufacturer direct sales 1 Year warranty

xduoo.net

Therefore I decided to have a closer look at the circuit.
Thereby I noticed these two transistors.

What do you say?
Is a power amplifier circuit possible, in which tubes and transistors simultaneously take over the amplification?

I have seen a circuit where a transistor was used to stabilize the power supply to the tube, which was also not actively involved in the amplification. Maybe something like this has been done here too?!

In the meantime I am working on some modifications.
- Dim display
- Replace potentiometer to ALPS
- tube rolling
(for now)

 

[Jimbob54]

It's a shame you dropped it on your cat...

 

[sarumbear]

I recently became the owner of the Xduoo TA-30.

View attachment 221473
View attachment 221474

Without going into detail, I would just like to mention in advance that I am very satisfied with this device.

One thing, however, has made me wonder from the beginning.
According to the manufacturer, two ECC 82 tubes are used for amplification.
Which is quite unusual in itself, since these tubes are more likely to find their place in the preamplifier.
In addition, then comes the very high specification of the maximum power of 3W RMS (32Ohm load)

View attachment 221475

xDuoo TA-30 Tube Headphone Amplifier - xDuoo official store

Worldwide free shipping Fast delivery, usually 3-5 days arrive Shipping via DHL, TNT or Fedex Original new product Manufacturer direct sales 1 Year warranty

xduoo.net

Therefore I decided to have a closer look at the circuit.
Thereby I noticed these two transistors.

View attachment 221476View attachment 221477View attachment 221478View attachment 221479

What do you say?
Is a power amplifier circuit possible, in which tubes and transistors simultaneously take over the amplification?

I have seen a circuit where a transistor was used to stabilize the power supply to the tube, which was also not actively involved in the amplification. Maybe something like this has been done here too?!

View attachment 221512

In the meantime I am working on some modifications.
- Dim display
- Replace potentiometer to ALPS
- tube rolling
(for now)

View attachment 221496View attachment 221497View attachment 221498

My initial question will be what are those IC are doing, especially that large multi pin one?

The second one will be why specify power at 32 ohms? Is that a HP amplifier?

 

[Bow_Wazoo]

It's a shame you dropped it on your cat...

I have never had a cat, and will most likely never have one

 

[Jim Taylor]

I have never had a cat, and will most likely never have one

I believe it's a joke, based on the very first photo. Jim

 

[Bow_Wazoo]

Oh well, now I check that.

Background:
I bought the TA-30 from someone,
who sold the device because of his cat.
This has damaged the device.
In another forum, I was asked about it, because the ad has probably reached a certain popularity...

So actually she deserved to end up as a "carpet"...

 

[Bow_Wazoo]

These two resistors , seem to have become quite warm....
Whether this is so normal...

 

[Zek]

Without a schematic of the whole device, it's hard to say what those two resistors are for, but it's obvious that they're suffering a lot of heat because they've changed color.
I don't think that's normal.

 

[loessi]

hi, i got this little headphone amp and was suprised about the sound, but

- its an hybrid amp ( 3 watts is too much for my sennheiser hd 800 300 ohms ), but i don´t care
- its an heater ........ i think the transistor on the bottem produce the heat,
and the housing encloses the heat, there is no dissipation.
did anybody consider to drill some holes in the bottom and may be on the the side
to cover the heat ??
anyway it is in germany pretty cold, so i love this little amp

-the most critical feature is the volume knop !!!! if i turn it only to the nine o`clock position
it blows my ears away.
which alps poti to install to cover this problem ?? 50k or more ? linear or logarirhmic ?
which alps serial number ??

thanks for replies

greetings from munich in germany
reinhard

 

[mhardy6647]

It's a shame you dropped it on your cat...

I am rolling on the floor.

 

[fpitas]

Without a schematic of the whole device, it's hard to say what those two resistors are for, but it's obvious that they're suffering a lot of heat because they've changed color.
I don't think that's normal.

It's normal if you push them right to the limit.

 

[mhardy6647]

It's normal if you push them right to the limit.

Which isn't exactly a best practice.

 

[Pflugshaupt]

I'm another TA-30 owner since about a year and like how it for its sound - when I'm not in the mood for clean amplification.
It does get extremely hot. Yesterday 'smoke of dying mosfets' came out of mine after about 3h of usage. I did add extra heat-sinks to the outside to make the case stay a bit cooler, but it doesn't seem to be enough.
Curiously enough, my unit does have cooling slots at the bottom, but on the inside the air can't really move well as the PCB blocks almost the entire space. At least the smoke got out around the rectifier tube. When I opened it up this morning, I was surprised to see more differences. The pictured unit has two transistors mounted to the bottom plate while in mine these are on the pcb?. Luckily, the amp still runs, but I don't want to use it for longer periods of time now.

I wonder which of us has the later model. On the backside there's a serial Mine is 03800303788. Could you check yours?

.

 

[Pflugshaupt]

.. oh and the two resistors on the top look like new on mine.. probably because I never let the thing run for more than 3 hours..!

 

[Pflugshaupt]

Turns out - upon further disassembly a ss34 diode has exploded on the small-tube daughter-board with the black heatsink. In my unit, the two transistors that are mounted to the bottom plate on yours are mounted the other way and have tiny aluminum heatsinks attached to condensers using thermal glue . So there are small internal heatsinks in the TA-30, but ventilation is really bad - rendering them mostly useless.

Now maybe my smoke was caused by the tip-50 doing extra work because of the missing rectifier diode. If I want to replace it.. the big question is - what direction was it facing when it was still there..?! @Bow_Wazoo , if you could share a picture of the spot.. that would be amazing.

 

[mhardy6647]

Now maybe my smoke was caused by the tip-50 doing extra work because of the missing rectifier diode. If I want to replace it.. the big question is - what direction was it facing when it was still there..?! @Bow_Wazoo , if you could share a picture of the spot.. that would be amazing.

I mean -- 50/50 odds. Way better than one's "March Madness"* bracket odds, or winning the lottery, or... most anything, really.
So, as Dirty Harry Callahan would have said, you have to ask yourself one question:

Sorry, I couldn't resist.
More on the probabilistic nature of reality at:

How Dangerous is AI?

Free will as it's normally conceived is a really flawed concept: My choices ultimately come from me, and me alone, unconstrained by the outside world, is about it? I agree that definition is over-simplified and untenable. ... Just being nondeterministic doesn't make free will self-causing, it...

www.audiosciencereview.com

__________________________
* This is an American collegiate basketball thing. Perhaps too abstruse (or regional) for an international forum?

 

[mhardy6647]

Oh, and somewhat more seriously -- and on point -- I'd be concerned as to the root cause of one diode in (presumably a full wave bridge) suddenly immolating, were it mine.
Perhapsjust one of those things (truly random event). Perhaps just a sketchy single component. Perhaps dangerously under-spec'd components (PIV or current rating).

To invoke another meme from my youth.

 

[fpitas]

Which isn't exactly a best practice.

I'm not arguing. Caveat emptor, and all that.

 

[Pflugshaupt]

The blowing-up might have happened because I'm using different tubes that draw more current?
Although the TA-30 gets far too hot, that's certainly not the cause for the blown diode. Still the cooling design really leaves me speechless. Also how psu/amp/digital parts share a single maze-like two-sided pcb.. all to save some space it seems - I'd prefer the device to be larger, have a logical structure and working cooling for sure.

 

[mhardy6647]

I'm not arguing. Caveat emptor, and all that.

Now we've seen what happened to a poor defenseless rectifier in one of these things...