Yes Dan, the OPA134 is a single op amp. A pair of those would fit just in.
Most of us here would meddle with the op amp to seek the flavour that suit us.
Therefore we usually populate the caps in the surrounding area of op amp on the underside of the board so that changing these chips is so much easier without the obstruction.
@dantwomey Add note : In case you are not aware, the opa1656 is available as single version - opa1655. They are worth trying.
Most of us here would meddle with the op amp to seek the flavour that suit us.
Therefore we usually populate the caps in the surrounding area of op amp on the underside of the board so that changing these chips is so much easier without the obstruction.
@dantwomey Add note : In case you are not aware, the opa1656 is available as single version - opa1655. They are worth trying.
Received the parts and since I am impatient, started putting it together. My first pcb in years and my very first SMD soldering - had to watch a video on youtube - it was easier than I thought but lets see if it works. 
Measured 0R resistors and they are 6mOhm - unexpected TBH. So I just used plain jumpers on power circuits.
I am a bit confused with the electrolytic caps. The positions on the board are significantly larger than any of the caps that I got. I followed couple different BOMs and somehow ended up with multiple options. Can you please help me choose:
Panasonic
47uF 25V https://www.mouser.com/ProductDetail/667-EEU-FR1E470
100uF 25V https://www.mouser.com/ProductDetail/667-EEU-FR1E101
4.7uF 50V https://www.mouser.com/ProductDetail/667-EEU-FR1H4R7
100uF 16V OSCON https://www.mouser.com/ProductDetail/667-16SEPC100MW
Kemet
47uF 25V https://www.mouser.com/ProductDetail/80-A750EK476M1EAAE40
4.7uF 100V https://www.mouser.com/ProductDetail/80-A759EQ475M2AAE160
Nichicon
4.7uF 50V https://www.mouser.com/ProductDetail/647-UMV1H4R7MFD1TE
Wurth
100uF 25V https://www.mouser.com/ProductDetail/710-860020473008
Also, any recommendation for power connectors that would not let me mix polarity?
Measured 0R resistors and they are 6mOhm - unexpected TBH. So I just used plain jumpers on power circuits.
I am a bit confused with the electrolytic caps. The positions on the board are significantly larger than any of the caps that I got. I followed couple different BOMs and somehow ended up with multiple options. Can you please help me choose:
Panasonic
47uF 25V https://www.mouser.com/ProductDetail/667-EEU-FR1E470
100uF 25V https://www.mouser.com/ProductDetail/667-EEU-FR1E101
4.7uF 50V https://www.mouser.com/ProductDetail/667-EEU-FR1H4R7
100uF 16V OSCON https://www.mouser.com/ProductDetail/667-16SEPC100MW
Kemet
47uF 25V https://www.mouser.com/ProductDetail/80-A750EK476M1EAAE40
4.7uF 100V https://www.mouser.com/ProductDetail/80-A759EQ475M2AAE160
Nichicon
4.7uF 50V https://www.mouser.com/ProductDetail/647-UMV1H4R7MFD1TE
Wurth
100uF 25V https://www.mouser.com/ProductDetail/710-860020473008
Also, any recommendation for power connectors that would not let me mix polarity?
Attachments
Usually you can find the dimensions of the part used in the DAC in the BOM, e.g:
12 | C203, C206, C303, C306, C401, C402, C405, C406, C407, C408, C409, C410 | 100uF | Nichicon | UKZ1E101MPD | aluminum elect | 25V | CP_Radial_D10.0mm_P5.00mm |
This 100uf Cap has a dimension of 10mmx5mm you should order one which has the same dimensions as the ones in the BOM.
Everyone has their own opinion and practice as per their own preferences, I prefer the connector type as you could see in the picture no chance of reverse polarity on the connector, with 18SWG wire crimped by myself and color coding which I could remember, also writing the polarity on each side of the connector with a permanent market so that accidentally I don't fry the chips (again)
Here is the link, now I prefer to use the RED ones.
Connectors
Edit: These are 4 pin version you can find 3 pin version as well.
Connectors
Edit: These are 4 pin version you can find 3 pin version as well.
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@Seavan,
Check out my post#4022, it has real Molex KK series parts sourced from Mouser.
https://www.diyaudio.com/community/threads/dac-ad1862-almost-tht-i2s-input-nos-r-2r.354078/page-202
Check out my post#4022, it has real Molex KK series parts sourced from Mouser.
https://www.diyaudio.com/community/threads/dac-ad1862-almost-tht-i2s-input-nos-r-2r.354078/page-202
These are good but I swear they used to be £20 or so. Also on AlieX
https://www.amazon.co.uk/PA-20-Universal-Open-Barrel-Micro-Fit-Mate-N-LOK/dp/B002AVVO7U?th=1
Can't seem to find anything else for Molex KK
It has an internal crappy opamp. Always an option, free too.
I guess the tube's mu will determine the IV resistor value. Err on the side of high mu. EF280 trioded, C3g.
Where did you get those 4mA from? RTFM usually a good idea.
you have a link about a paper about tube and these ics from T Loesch. Miro's blog link first post !
Michelag Hi,
I don't usually buy tools from AExpress for various reasons, as for crimping tool there is a retail outlet for ProsKit in my city of residence for a very long time, I usually buy tools from them.
For crimping I have a couple of them and they are variants of the following one:
https://www.prokits.com.tw/Product/CP-751A/
100ohm you're good to go with my (well, grunf's) tube output stage. Look back, I uploaded a Gerber (I think I'm going update it since I forgot the pads for screws, otherwise it remains the same) and the schematic with it's PSU.
It is by far the best sounding piece (but with ad1862) that I ever built.