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Hi!

Welcome to my DIY audio forum.

Cheers
Per-Anders Sjöström

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#91
Headphone amplifiers / Re: QRV-08 power up
Last post by svarthvitt - 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!
#92
Headphone amplifiers / Re: QRV-08 power up
Last post by peranders - 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.
#93
Headphone amplifiers / Re: QRV-08 power up
Last post by svarthvitt - 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?
#94
Headphone amplifiers / Re: QRV-08 power up
Last post by peranders - 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.
#95
Headphone amplifiers / Re: QRV-08 power up
Last post by svarthvitt - December 25, 2018, 07:55:28 PM
Yes, the resistors are 470k, and the opamps are in the right direction.
#96
Headphone amplifiers / Re: QRV-08 power up
Last post by peranders - 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?
#97
Headphone amplifiers / Re: QRV-08 power up
Last post by svarthvitt - 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
#98
Headphone amplifiers / Re: QRV-08 gain reduction
Last post by peranders - October 30, 2018, 07:05:41 PM
R14 and E14 can be changed. 330 ohms will set the gain to 2.
#99
Headphone amplifiers / QRV-08 gain reduction
Last post by Discom - 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?
#100
Headphone amplifiers / Re: Using QRV-08 as a Preamp
Last post by chinook9 - July 24, 2018, 04:12:51 PM
Thank you P-A.  I suspected as much but I wanted to confirm it.

The original enclosure I used is a bit too small and I have not completed a neat installation.  I recently received a slightly bigger enclosure and I may have room to put in RCA preamp-out jacks.

The QRV-8 sounds as good as a preamp as it does with headphones.

Thanks again


Brian