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Headphone amplifiers / Re: QRV-08 power up
« Last post by peranders on February 09, 2019, 09:19:36 AM »
I'll suggest that you try to get a working power supply first. Then you'll have to cut four traces, the power lines to each amp.
2
Headphone amplifiers / Re: QRV-08 power up
« Last post by svarthvitt on February 08, 2019, 05:46:04 PM »
Hi again,

Yes, the electrolytics are mounted correctly.

The supply lines seems to go to a lot of components in the amplifier, could you tell me the part numbers to remove and where to measure the voltage?


Thank you again!
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Headphone amplifiers / Re: QRV-08 power up
« Last post by peranders on January 02, 2019, 07:35:54 PM »
Are all electrolytic caps mounted correctly? Both channels are dead? If yes, then it's not a random error.
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Headphone amplifiers / Re: QRV-08 power up
« Last post by svarthvitt on December 31, 2018, 01:16:34 AM »
The amp was working for a while before it went silent.

Should I disconnect the supply to the psu or the amp? I would guess the regulators behave badly with no load?
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Headphone amplifiers / Re: QRV-08 power up
« Last post by peranders on December 27, 2018, 03:11:16 PM »
I'm trying to get the picture. The amp worked good and then after some time switched off it doesn't and the both channels seems to have the same fault?

I recommend that you cut the supply lines to both channels. Check that you have the correct voltage. 13.93 V is the typical value.
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Headphone amplifiers / Re: QRV-08 power up
« Last post by svarthvitt on December 25, 2018, 07:55:28 PM »
Yes, the resistors are 470k, and the opamps are in the right direction.
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Headphone amplifiers / Re: QRV-08 power up
« Last post by peranders on December 16, 2018, 10:48:12 AM »
The R29 should be 470 kohm. IS it really this value? Is the opamp soldiered in the right direction?
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Headphone amplifiers / Re: QRV-08 power up
« Last post by svarthvitt on December 15, 2018, 08:57:42 PM »
heaveno again,
I tried making this amplifier work again. I replaced some parts and looked over everything again once more. I really cannot find the fault here.
I tried filming the amplifier with a thermal camera, and BR1 and BR4 are running really hot. None of the resistors or silicone in the middle seems to heat up, except E29 and R29.

Does this help at all? Any other input on what I could try? I really want this thing running.


Regards,
Svarthvitt
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Headphone amplifiers / Re: QRV-08 gain reduction
« Last post by peranders on October 30, 2018, 07:05:41 PM »
R14 and E14 can be changed. 330 ohms will set the gain to 2.
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Headphone amplifiers / QRV-08 gain reduction
« Last post by Discom on October 29, 2018, 09:59:22 AM »

I’ve completed the QRV-08 a few months ago and it has playing happily ever since. You weren’t kidding when you said it reveals poor recordings. I'll post a picture when I get around to taking one.
 
I’ve found the standard gain of 4 to be too high with an AMB gamma 3 and a set of HD650s. Which resistors should I change to reduce the gain, and what values would you recommend for a gain of 2 or 1 respectively?
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