DIY audio upgrade to OT

Elektron Gear Octatrack
#102

When installing the new opamps you have to be careful with the orientation. The pinouts are symmetrical on both sides so it should still work even if inverted. But if you place them the wrong way round the supply voltage will be inverted which will invert the signal.

There’s the convention that pin 1 is marked with a dot but unfortunately TI decided to ignore that convention and mark the side of the chip with the first and the last pin with a big bar. This is confusing so the chip might have been inverted.

Besides that the circuits are independent and protected from crosstalk (stereo image alteration) even under extreme conditions. I don’t think that should be a problem if everything is soldered correctly. I’ll have a deeper look into that next week.

6 Likes
#103

that makes sense! I thought this stupid bar on the side was the mark for pin 1.
BTW. Did you noticed a small volume drop after the you installed the new chip? I don’t know if it’s my imagination, but I think I’m receiving lower levels than before.

Thanks for your input

2 Likes
#104

No volume drop. I did a before/after recording and it was close to 1db louder after the mod.

1 Like
#105

ok, that could be a consequence of the inverted chip

#106

So just to be clear: the bar is on the side where the dot should be. If that’s the way you have it then the orientation should be correct. It marks the side of pin one and 14. It should be on top on the side where the jacks are.

4 Likes
#107

ah ok, than it’s correct. The line crosses the 1 and the 14 chip (and I can read the model number at the same orientation as the original chip)

1 Like
#108

I love that you guys are cracking open OT’s and modifying the internals, I’m not brave enough yet but maybe in a few more years… What’s else can we switch up in there? :smiley:

#109

I’ve seen screen mods that invert colors. Black background with white letters.
Looks awesome and it’s $60.

3 Likes
#110

Nothing really. It’s all tiny surface mount parts. I’ve seen someone doing a digital out mod but it is not as trivial as this one because you have to add some parts on a separate little circuit board for the signal conversion to spdif.

In fact I wouldn’t even recommend this opamp mod just yet before me and the handful of brave people who went ahead did some more extensive testing to confirm that everything works fine and the sound improvement is worth the effort and the risk.

4 Likes
#111

I’ve seen things you people wouldn’t believe.

Attack ships on fire off the shoulder of Orion.

I watched c-beams glitter in the dark near the Tannhäuser Gate.

7 Likes
#112

Lucky you!

That’s what I, earthly peasant saw:

escreen.jpg1191×865 197 KB

2 Likes
#113

Great find, I could not resist the Bladerunner joke though :wink:

1 Like
#114

Digital multitrack out would be a dream for studio use. Got any details on this mod? If someone offered a kit it would probably do pretty well.

#115

an ADAT out mod for getting all the 8 audio channels separately might be a cool mod as well…

3 Likes
#116

Another possible chip to use:

http://www.analog.com/en/products/amplifiers/operational-amplifiers/ada4610-4.html#product-samplebuy

Havn’t got time atm but this is the one will put in if and when i feel like doing some solder surgery.

#117

I don’t have any details on it, I’ve only seen some pictures on the webs. It would only give you a digital version of the main and cue outs though. The actual mixing of the 8 tracks happens inside the microcontroller. There’s no way to tap into that.

1 Like
#118

I just did some more testing with my modded OT and I can confirm that there’s no phase inversion or stereo image problems when this mod is done properly. My OT works perfectly fine.
I’ve been in contact with denoise and the reason for his issues was that he damaged some traces on his PCB, which is the reason why he got an inverted signal on one stereo side and the level was a bit lower. So here’s another word of caution: Please only proceed with this if you feel confident with SMD soldering!

If the mod brings any significant enough audio improvement that is hard to say. I feel like it does but I didn’t do proper before/after recordings. I am curious about it though and many others on here are curious too it seems. I don’t have a second OT, but I currently live in Stockholm. So if someone wants to swing by for a coffee and bring his OT along we could do a shootout with a short piece of music and record it here into my Fireface. We could also record some synths recorded through the modded and unmodded OTs.

The other option is someone with the exact same interface (Fireface UC) records a piece of music that we exchange and I record it here at the exact same settings. It should be a short piece with sharp transients, deep bass and top end detail, like a little bit of everything.

4 Likes
#119

http://p.matrixsynth.com/2012/03/modified-elektron-octatrack.html is the nearest detail I found, including a contact address for the individual who made the modification. They’re an ex-employee of http://www.atoll-electronique.com/en/ according to the info there.

This mod is complex. I have intercepted the digital stream between the DSP and the audio codec. Then a FPGA and a DIR (on the bootom of the yellow board) encode the I2S to a SPDIF signal. I also have added a coax connector that outputs the master clock to be compatible with pro audio gears.

2 Likes
#120

I opened the OT again and re-soldered the joints in the right position. No change. BUT I noticed something very interesting.

I have the theory now, that every OT (modded and un-modded) makes a small phase change, and that over time. It’s not a simple phase inversion.

So I suggest to do the same test as me. Send an audio file to the OT digitally, play it back and record it again. Look at the waveforms closely or even align them perfectly and play them together and hear the phase cancellation.

It would be very interesting to read your opinions.

#121

but earlier you stated that you do have a fully inverted phase. has that changed? because i don’t have anything like that. also i checked the recorded output in my DAW. i zoomed all the way in and i could not detect any misalignment at all on my modded OT.
also when you do the test did you make sure you used a mono sample and you turned off all effects that mess with the stereo image (like reverb, chorus, etc)?