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'Hot-swapping' inputs on Lepai and other Tripath amps?
'Hot-swapping' inputs on Lepai and other Tripath amps?
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Old 5th December 2013, 12:07 PM   #1
Aleksunder is offline Aleksunder  United Kingdom
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Default 'Hot-swapping' inputs on Lepai and other Tripath amps?

Does anyone know if there is a risk of damaging the Lepai TA2020 (or any other Tripath amp) by hot-swapping input connections, IOW, while they're powered up?

The Lepai has both RCA and 3.5mm mini-jack inputs, many have only the mini-jack - I'm wondering if the mini-jack in particular (which is the one people would be most likely to do this with) night be risky because of the momentary short between contacts.

Last edited by Aleksunder; 5th December 2013 at 12:11 PM.
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Old 5th December 2013, 12:11 PM   #2
Saturnus is offline Saturnus  Denmark
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There is. In fact, it's probably the third most common cause of burnt of chips after shorting the output and reverse polarity supply voltage.
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Old 5th December 2013, 12:19 PM   #3
Aleksunder is offline Aleksunder  United Kingdom
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Originally Posted by Saturnus View Post
There is. In fact, it's probably the third most common cause of burnt of chips after shorting the output and reverse polarity supply voltage.
Thanks!

Ouch.

The reason I ask is that I leave two TA2020's on 24/7 (Lepai and Indeed), but after I recently began using them with the output from my PC's soundcard (M-Audio Delta), there's a loud crack/thump when the PC boots and shuts down.

So a couple of times I've disconnected the Lepai (which loops through to the Indeed, bi-amping, effectively), after booting and before shutting down.

I'll desist, and either turn the volume down or switch them off form now on!
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Old 5th December 2013, 01:20 PM   #4
Saturnus is offline Saturnus  Denmark
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Clamping the input would also remove the danger of burning off the chip but the pop would remain (although much lower). Of course, that's not really practically possible on a finished amp like Indeed and Lepai unless you have quite the skilled hand at SMD soldering.
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Old 5th December 2013, 08:59 PM   #5
Aleksunder is offline Aleksunder  United Kingdom
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Originally Posted by Saturnus View Post
Clamping the input would also remove the danger of burning off the chip but the pop would remain (although much lower). Of course, that's not really practically possible on a finished amp like Indeed and Lepai unless you have quite the skilled hand at SMD soldering.
To be clear;

My PC is my media centre. It does everything, often via WMC, often via Foobar 2K (for music), and always for movies.

The M-audio's analogue-out is connected to the Lepai via its 3.5mm jack.

The lepai powers a JPW passive sub (12 ohm - no more than 7-8w per channel, but the high impedance makes for tight bass).

The Lepai's RCA out is looped to the indeed, which drives Wharfedale Diamond 9.0's, their ports plugged with foam bungs.

I set the volume on the TA2020's and leave it there (using them as power-amps, I guess) and use the PC's volume control (WMC remote).

I'm assuming, given all processing within the PC is at 24-bit, that I'm not losing much fidelity when it's attenuating output this way.

I have to say - the result is magical. I've been listening to albums I've known for almost 40 years, and hearing detail and inflection I never did before.

But the problem is the thump/crack from the M-audio at boot and shutdown.

I would like to leave the TA2020's alone, powered-up 24/7, not have to switch them on/off or twiddle their volume knobs every day.

Given it's an analogue line, I doubt the crack/thump from the M-audio is anything but a nuisance (it makes me jump, but I don't think it's damaging the TA2020's or the speakers they drive) so I reckon I'll just put up with it.
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Old 5th December 2013, 09:44 PM   #6
Aleksunder is offline Aleksunder  United Kingdom
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I should add;

I've experimented with various interconnects in this set-up.

A DNM Reson helped.
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Old 5th December 2013, 09:53 PM   #7
Saturnus is offline Saturnus  Denmark
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Maybe I should clarify that a clamp is a diode clamp that you put on the input in the amplifier itself after the input cap and input resistor. It simply limits the voltage the input of the amplifier chip can see to a voltage set by the clamping zener diodes thereby eliminating the possibility that a voltage spike can damage the input on the chip.
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Old 5th December 2013, 10:45 PM   #8
Aleksunder is offline Aleksunder  United Kingdom
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Originally Posted by Saturnus View Post
Maybe I should clarify that a clamp is a diode clamp that you put on the input in the amplifier itself after the input cap and input resistor. It simply limits the voltage the input of the amplifier chip can see to a voltage set by the clamping zener diodes thereby eliminating the possibility that a voltage spike can damage the input on the chip.
Yep, understood.

But;

I'd have to implement this with both my TA2020's (Lepai and Indeed), and frankly, it's not gonna happen! At least, not any time soon.

Seriously - what I'm listening to doesn't need any molestation.

However, your info is now here for all those who might want to action it.

Many thanks!!
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Old 5th December 2013, 10:52 PM   #9
Aleksunder is offline Aleksunder  United Kingdom
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Quote:
Originally Posted by Saturnus View Post
Maybe I should clarify that a clamp is a diode clamp that you put on the input in the amplifier itself after the input cap and input resistor. It simply limits the voltage the input of the amplifier chip can see to a voltage set by the clamping zener diodes thereby eliminating the possibility that a voltage spike can damage the input on the chip.
BTW - I'm hoping - HOPING - that the "voltage spike" you mention (and which my sound card is outputting at boot/shutdown) isn't outside the normal output of an analogue line.
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Old 6th December 2013, 12:22 AM   #10
Saturnus is offline Saturnus  Denmark
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Quote:
Originally Posted by Aleksunder View Post
BTW - I'm hoping - HOPING - that the "voltage spike" you mention (and which my sound card is outputting at boot/shutdown) isn't outside the normal output of an analogue line.
It most likely is, at least with a normal sound card. Have you measured it? Luckily, the chip can take some abuse, just not excessive like you'd see in car audio or pro audio where the signal voltages are normally higher.

Last edited by Saturnus; 6th December 2013 at 12:26 AM.
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