DIY 5k Monitor - success :-)

[zalle]

Guys, after converting a 2015 27" (5K), I am thinking about my next conversion. I have 2 options:

2017 27" OR 2012 27"

I know the 2012 is not 5K, but my 5K 2015 only works with HDMI, so I'm not getting 5K anyway... Correct? But it's fine.

Will the 2012 look the same as the one I'm using now? The 2017 machine is still pretty good, with 40GB ram, so it's kind of a waste, if it's not going to be much better... What do you think?

 

[PaulD-UK]

@zalle
Converting a 2012 27" iMac is more problematic, because the very cheap and basic 2K conversion boards were not designed for an iMac panel, and getting the backlight bright enough can be a problem, resulting in a dark screen.

They also are not as efficient, so use as much or more power to run than the 5K conversions.
The other problem is that MacOS no longer (after High Sierra) looks as good on non-retina screens.

Your JRY-W9CUHD-AA1 conversion should work at 5K using DP or USB-C, and getting a replacement board or upgrading to a JRY-W9RQUHD-FA1 or SA1 would give a much better monitor.

If you do convert the 2017 monitor then that has a better screen panel, and would be a better conversion with a more expensive board.

It's best to deal with a supplier who tests the board you buy before they ship it too you.

 

[itlnx]

Hi everyone! I’m trying to use my iMac Pro (A1862) as a monitor, but I’m having trouble with the sound. Does anyone else have the same issue?

I’ve looked into the 820-00967 schematic and found 4 digital amplifiers that work via I2C. I think the crossover parameters are handled by the T2 chip, the TAS5764L (unfortunately no datasheet available), or the CS42L83 — I’m not sure, and I can’t figure it out.

Could someone please measure the working frequencies for the tweeters and subwoofers with an oscilloscope?

 

[PaulD-UK]

@itlnx
Good luck with your iMac Pro conversion.
Please share the details of how it works out here.

I've done a DIY 5K monitor conversion using the speakers from an iMac Pro (in an ordinary iMac case).

The crossover in an iMac Pro is indeed a function of the T2 chip, feeding directly into the fixed gain Texas Instruments TAS5764L audio amplifier chips that connect directly to each of the four speaker drivers.

The speaker drivers are 4 ohm, and I have not used an oscilloscope, but listening to an audio frequency sweep there is a pronounced resonance peak for the tweeter between 2.5-3KHz.

Listening tests gave me a best -3dB crossover point high enough above 3KHz to roll off the tweeter response to smooth out the resonance.

I get excellent results with this 10uF tweeter/0.16 mH crossover - giving this (theoretical) audio plot, which puts the resonance -5-6dB down.
The low frequency speaker is well enough behaved to not need a more complex crossover.
Keeping the crossover frequency fairly low enhanced the audible stereo listening experience.

Because of the power of the low frequency drivers it is essential to have nothing loose, or not fixed securely inside the iMac case, or you will get severe rattling...