bsl, my next trip to your place, I'll pick them up pronto. I've got various assortments of 12 volt DC fused/unfused cables in hand, including those thick stiff battery to battery transfer ones...we'll see if cables make a difference too!

hey Y.C....I like music.....I like your T-amp very much.....I do admire the quality and its capability.....don't get me wrong....is just that I have few 'matters' to settle first before jumping into class - D session.....my experience in personal with T-amp is just inspiring for me.....really....

like uncle jazzy said......I'm not in the moment of jumping into this path yet......but soon I'll be like you too....

gabanyayaya, I wish I had your resolute resistance to this involvement.

but you don't right....hehe it's ok.....who can resist to such temptation......and the COST me too. It's just that I like to make some slow and steady approach he. No need to be hasty......

Guys, i have a problem with tamp here. the power off thump noise still exist, it plays for uncounted hours ald. some of u said after the burn in, the thump noise will disappear, but its not the case for me. any idea?

wui,
That was reported by Y.C. some postings back. On my side the 'thumping' or inrush current sounds did subsides somewhat but I do not know if it has disappeared altogether as I am using a speaker relay/delay board. There were also some 'noises', mild ones from Junior's T-Amp but I don't think there are any now..
Have no idea how to help you/your board...

p/s
There is some 'noises' from Junior's T-Amp but only on the right channel..

This post has been edited by jazzy939: Nov 15 2008, 06:42 PM

What input capacitors and value you’re having in your T-amp? I believe these are culprits to the 'thump' sound you’re hearing.

In my case, I leave my T-amps permanently on, hardly switching them off. When they’re newly soldered including my well run-in 1st T-amp board (fixing it into an aluminium casing with new wires and speaker binding posts) which I reported no 'thud' sound earlier, I heard it but it disappears the moment the sound becomes run-in again.

Y.C., now I understand why you don't go for battery power. Yalah, quite inconvenient in this case, to have to shut down and disconnect the battery for charging every few hours or so.

wui, do you get the thump if you turn the volume down to minimum, wait about 15-30 seconds and then power down the T-amp?

This post has been edited by March05: Nov 16 2008, 12:25 PM

March,
I'm not going for battery power although I've read and convinced of its benefits. It's the convenience I'm after instead of absolute sound quality; my T-amp is not part of my main system at home. On leaving my equipment permanently on, I was made to understand that the capacitors of these equipment would last longer than the constant switching on/off.

On the switching-on thump sound, the wiki of diyAudio.com (URL provided in earlier posting) has this to say on "Which input cap is best? What size cap do I need?" - No one has yet to establish a "best" cap. Any good metalized film or film/foil cap will make you happy. Some users have reported preferring electrolytic cap, such as Blackgate, for more bass impact. A value of 2uF or 2.2uF is as large as you need. Voltage can be as low as 5V. Bigger sizes, say 4 to 10uf, will definitely give a big switch-on thump.

Some of us ask questions and once the questions are answered, they would then gleefully disappear without any sort of acknowledgement.

---

Added on November 16, 2008, 4:35 pmWe thought you're truly a music lover, and that is a compliment.

Take your time, bro.





This post has been edited by Y.C.: Nov 16 2008, 04:35 PM

I will.....

Y.C I heard that you have participate in bulk order from hohodiy and you booked an alps volume pot....!!!! May I know is that the original 100K Alps pot or some replica selling widely on Ebay....????

Y.C., for the sake of discussion, a capacitor primarily functions as a on-off energy storage device, i.e. it is constantly charging and discharging while you are using the amp. So how much difference would it make if you manually power it on and off a few times a day compared to the billions of times it's doing that in its lifetime? I would think that leaving it on all the time (and thus keeping it heated up) would be a bigger drawback to its lifespan as constant heat would contribute significantly to the fatigue of the internal components of a capacitor.

In practice any capacitor will last at least a decade or more regardless of how your equipment is being used. Similarly, there may be anything from a hundred or more capacitors inside a television set and contained in a very hostile enviroment, it'll still last for at least one and a half decade and anyone would think of dumping it by that time.
Capacitors may not last if its pushed to its operating limits in voltage and temperature.

Of course, any unusual condition involving overvoltages and sudden temperature changes can cause premature death of a capacitor. But isn't it heat (over a long period of time) that ultimately reduces the normal lifespan of any electrical/electronic component?

BTW my 25" Sony TV has gone two decades without a single failure of any of the capacitors. But it has failed a couple of times due to solder fatigue...and one case of a push-button power switch failure. Current problem...thanks for your strong hint, bsl555, seems to be one obscure wirewound resistor which has somehow increased its resistance. Oh no, I'm not dumping it yet.

i'm using 2.2uF input caps. sorry for being inactive in discussion, still on medication, have been suffering from fever for few days.

March08
Sorry for off topic, it should look like discolored metal oxide 1-2W resistors that have failed due to over current draw. From past experience, many solder points on the power rail can easily deteriorate causing all sorts of malfunction and intermittent problems. Often the solder points are even seized to the point of no repair and have to be re-routed with point to point and hard wire. I've seen this kind of problem too often on Sony TV sets.
Back to capacitors. General Caps are rated at 85deg C and 105degC for hd ones. Thats quite hot in really. Water boils at 100deg C..so you may imagine the heat. I don't think any cap would reach even half that temperature.

bsl, I couldn't find any metal oxide resistor with discoloration or obvious damage on the board. I also checked and tested most of them with the multitester - so time consuming lah. But I found a wirewound one at the corner of the board, which should be 0.1 ohm (it's clearly printed on the side of the resistor as 0.1 Ω, 2W), but measures 1.1 ohm instead. I'm assuming that this is not normal and will replace it to see if it is the cause of the problem. If the board still doesn't come back to life, the hunt continues.... okay, no more Sony TV stuff in a T-amp thread, sorry about that folks.

Back to the discussion again. I'm not talking about heat levels which exceed the limits stated on the caps - going above those will likely cause immediate and premature death, which is a different issue. I'm pointing out that in most electrical components, the reason why there is a limit to the life span is that any component will invariably deteriorate from heat (it doesn't even have to be exceedingly high temperatures) damage over its working life. If a component could be run in a constantly cooler environment (even a few degrees lower can make a difference), it will average a longer life span, all other factors being equal. How much longer it would last is also dependent on the manufacturers' design specs and the actual quality/tolerance of the materials used, of course.

Gabanyayaya,
I'd not be able to tell whether those Alps Blue A X2 / RK27112 going for sale at eBay for RM56.XX (USD16.XX) are only replicas and not the real thing themselves. The representation made is they are genuine. Yes, I joined hohodiy bulk order and bought one 50K pot for myself, again not 100% sure it is not an imitation although I doubt it is fake.

I am not really a believer of Alps volume pot. Built-wise, it may be better than the Alpha pots from JP but in term of sonics (transparency and musicality), no way near the resistor type. And I am not alone in my thought, see the following comment at Audiomahus:

"You will find a new volume control potentiometer, the Precision Electronic Components (PEC) volume pot. Made in Canada, this all-carbon POT with a solid-carbon wiper is resin sealed and built to military specs. We spent a long time searching for a great pot and we found something very special with the PEC. It is transparent and very musical ?span style="font-size: 10pt;"> more detailed than the Alps Blue, but with the mass and substantive build that the Alps lacks"

March, I agreed with this part of your comment - "a capacitor primarily functions as a on-off energy storage device, i.e. it is constantly charging and discharging while you are using the amp." I'd think during standby mode, the capacitors are not working (charging and discharging) but merely getting ready to work anytime. Although the T-amp's TA2024 chip is not a capacitor, it runs hot when music is playing and when all is idle, it gets cold again although the amp is still being powered up.

I believe in more damages being inflicted to the capacitors during powering up, just like cars during their cold start in the morning, as a result of sudden insurge of current into them. Perhaps I may have been incorrect, but I believe that "...for the best sound quality, our systems should be left on all the time. They give the best performance, the best ultimate sound quality and according to studies carried out, equipment left on all the time has a reduced incidence of breakdown. Switching electronics on puts enormous stress on the internal components and this shock damage is the main reason for component failure." quoting the words of RA.


This post has been edited by Y.C.: Nov 16 2008, 11:48 PM

yep..i see that quote from M. Mardis in his T-amp website before. But...if you're a non believer to Alps then why don't you just get JP one instead choose the hohodiy Alps pot....???? Is it just because of it sonics improvemet made by this Alps pot, you've decide to get one ???? Are you sure there's an improvement to the T-amp???

I'm soo curious....

Gabanyayaya, I already have the RM2.50 Alpha pot from JP in my second T-amp. I am getting the Alps RK27 as it is better built and should make a slightly improvement to the sonics of my T-amp at RM30 thereabout.