T-Amp hiss/crackle in channel - diyAudio
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Old 6th October 2005, 04:51 AM   #1
nehpets is offline nehpets  United States
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Default T-Amp hiss/crackle in channel

well, im obviously new here. but this seems to be the best place to ask questions about the t-amp.

i just ordered myself one and it came in the mail yesterday. i played it for maybe 10 mins then. today i played on it for an hour or less and i noticed a crackle/hiss in the left channel. its always when the song hits alot of treble to. the mids aren't affected.

im running off of a Wall Wart(12V, 1A) and my speakers are from my stereo(sony, 6 ohm)

i know its the left channel and not my speaker because i've switched them around and its always the one plugged into the left channel, a very annoying hiss/crackle.

help please. i would very much like to enjoy the same thing that everyone else has enjoyed with this little amp. but my first experiences with it have been crappy.
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Old 6th October 2005, 02:58 PM   #2
Livino is offline Livino  Brazil
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Hi, I'm facing a similar problem with my T-Amp.

In my case I'm pretty sure both channels hiss, and there's also a noticeable "humm" in the middle third of the volume scale. It disappears below 1/3 and above 2/3s volume. But the hiss stays, and it's specially loud from the tweeters (as expected).

I'm blaming it on my power supply - it's a 12V 2A switch mode thing that looks like a Nokia mobile phone charger. It plugs into the wall, so I'm guessing it's a "wallwart" too (though I'm not familiar with the term).

Are you using a switched or linear PSU? You can tell by the wheight of the thing.

I've been searching for a definitive answer to the "correct power supply for a T-Amp" question. So far, unsuccessfully. Some folks swear by SMPS, others say linear is the way to go. It seems that switched mode supplies tend to add a fair bit of noise that is combined with the amp's own noise (since it's sort of a switched mode PS for the speakers after all).

The hummmmmmm that only appears within a certain volume range seems to be a different challenge altogether. I'll try yet another linear supply later today or early tomorrow and will report back here.

Also, there seems to be a noise problem with some T-Amp units. Maybe you should look into that too.

Keep us posted, we want our T-Amps to rock!

Cheers,
Livino
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Old 6th October 2005, 05:47 PM   #3
nehpets is offline nehpets  United States
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thanks man !

as far as the power supply goes. im not to keen on all the different kinds. all i know is its your basic AC to DC supply, like the ones you see for almost any electronic appliance around the house.

i have a friend who's a major audiophile and i will let him check it out. hopefully he can help me also(and you to)

but thank you for keeping me posted on this ! i hope we can figure out this problem
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Old 6th October 2005, 08:31 PM   #4
Nuuk is offline Nuuk  United Kingdom
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Nehpets - Are you certain that the problem isn't elsewhere in your system? I made some mods to a class-T amp this week and when I powered it up again, I had a hiss. I spent a few hours checking over the amp, only to find out that it was a bad connection from my DAC!

Quote:
I've been searching for a definitive answer to the "correct power supply for a T-Amp"
Livino - Don't waste your time looking for definitive answers on these forums. But take my word for it, SMPS is the way to go.
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Old 7th October 2005, 06:26 AM   #5
jwb009 is offline jwb009  United States
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I'd just like to reply that I'm also experiencing these problems with my t-amp hooked up to my computers psu. I'm thinkin about getting an SLA to see if it helps things out. I hope we can get a definitive answer to what makes and models of power supplies people are using with good results.
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Old 7th October 2005, 12:55 PM   #6
Livino is offline Livino  Brazil
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I found a company in my city that specializes in custom-made power supplies. I've ordered a 13V 1.25A linear PS from them which I'm picking up today.

Custom-made stuff is kind of expensive as you can imagine, so cost ruled out a 2A supply. The 1.25A box is plenty expensive already at about $55 - $15 more than what the T-Amp cost me with postage to Brazil included...

Anyway I'll post my impressions later today.
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Old 7th October 2005, 05:28 PM   #7
Livino is offline Livino  Brazil
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Default UPDATE

Ok, I just got the new custom-made supply. I didn't have that much time to test it during my lunch break, but at least it didn't hum or hiss or anything. Good sign...

Well, there is a very, very faint hiss from the tweeters if I crank the volume up all the way. The hum in the middle 1/3rd of the volume scale was initially there but disappeared completely after I accidentally switched the power supply off and on again a couple of times (the connector was a bit loose, it's fixed now).

I nicked a 12V 1.25A switch-mode PS from my brother's Cannon scanner to compare sound quality later today. Good thing that they have identical output specs, too bad I didn't notice the Canon PSU earlier or I might have saved the money spend on the Nokia-looking thingy. But the linear PSU is looking promising!

I'll keep you guys posted on my testing, but so far the linear box is a clear winner.
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Old 7th October 2005, 07:32 PM   #8
joesan is offline joesan  United Kingdom
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Nuuk - interesting that you are recommending a SMPS. I started another thread trying to get some guidance on the right kind of psu to use with the AudioDigit t2020-m. So far plenty of views but no answers!

Anyway as I say interesting that you are saying SMPS, the autocontruire site says get a linear 11-13.5v 3-5A. Do you know anywhere one could source a readymade SMPS version with those specs in the UK?

Judging by appearances your a man that knows what he's talking about on these forums (but you know what they say about judging by appearances...
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Old 7th October 2005, 07:44 PM   #9
Nuuk is offline Nuuk  United Kingdom
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Quote:
Judging by appearances your a man that knows what he's talking about on these forums (but you know what they say about judging by appearances...
Yes, be warned, I know very little!

I tried a wallwart, a home-built regulated linear supply, SLA battery, and one of those SMPS modules and I can honestly say that the SMPS was clearly the best sounding supply. If Leo is watching this thread, he will confirm what I say.

Quote:
Do you know anywhere one could source a readymade SMPS version with those specs in the UK?
The ones on DD are ready built. All you have to do is wire them up and add a loading resistor to the 5 volt output. You can buy similar modules all over the place (for a lot more) but I don't know of any completely finished examples (ie with cases, switches and sockets).

I hope to be able to offer a finished version of the SMPS in a rather smart casing in the not too distant future!
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Old 7th October 2005, 08:25 PM   #10
t. is offline t.  United Kingdom
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I've tried a few different diy PSU's, regulators etc for my Amp3
I also used 12v 7aH batteries with and without 10k caps on the output.
NUUKs SMPS was the last I tried and to be honest it easily gave the best results
Fit a good 10'000uf cap on the output the music just sounds more right
I've had very good results with the SMPS powering other parts of my Hi-Fi too
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