If you are planning on using Melbourne with the Yarra motherboard, you do not need to populate the input and output cap coupling sections on the Melbourne. Instead, replace with a jumper as shown and populate the Yarra MB to give yourself more room so you can use bigger and better boutique caps if desired. The output can be DC coupled if you wish (0mV to 20mV of DC offset depending on how lucky you are with all your components selected). If your amp has an AC coupling cap, definitely don't need it on the Melbourne/Yarra.
Attachments
In case anyone is wondering what to use for heatsinks, I think something like this might work:
https://www.ebay.com/p/10-Pcs-21x15...nsistors-K1o6-Wi/13020216620?iid=113054098164
https://www.ebay.com/p/10-Pcs-21x15...nsistors-K1o6-Wi/13020216620?iid=113054098164
I like to sleep in as much as the next guy, but I have too much fun staying up and building things to sleep. Truth is, we all have things we need to do, and things we must do. The things we want to do, end up being relagated to the leftover remains of the day (or early morning). Time is infinite in length but we never have enough of it.
Vunce has gone through the painful process of getting a Mouser shopping cart together for the Melbourne. It’s a lot of work to do this, so please join me in thanking Vunce for his efforts. This shopping cart is for 1 Melbourne, so double order for a pair. I still need to verify if all the pairs are here and correct - maybe someone else can help out with that.
Mouser Electronics
Mouser Electronics
I just received then order from this shopping cart and went through it compared to the schematic. There are a couple of changes that are needed:
R104 received was a 14.7k 1% when it should be 14.9k 0.1%
R106 received was 15k 1% when it should be 0.1%
C116 received was 33pF 16v C0G 1206 and should be 100v NP0/C0G this one needs to be replaced, as the low voltage rating may cause distortion when driving at higher voltages.
The two values R104/106 are needed to be precise 0.1% tolerance to tweak the output DC offset as close to 0mV as possible if running DC coupled mode. If you will be running AC coupled mode it won’t matter. Also, until one takes all the variations on the DC offset path, it may not matter as the voltage drop across the transistors also come into play. It’s not a big problem - and it will still work fine. You may get 15mV offset but that may not matter anyway.
For the output coupling cap, I spec’d a 47uF electrolytic. For those of you intending to drive the Edcor on the M2X, that’s a 600ohm load, so something like 220uF would give deeper bass flat to 5Hz vs 20Hz as you would have for 47uF. I picked the Nichicon Muse series 220uF 50v (UKZ1H221MHM) for this. It’s a bit big and will have to stand up kind of high to clear the other parts or you might even try 100uF which is smaller diameter. Although the 47uF will sound just fine too unless you are trying to listen to home theater rumble.
Otherwise the Shopping Cart above is fine.
R104 received was a 14.7k 1% when it should be 14.9k 0.1%
R106 received was 15k 1% when it should be 0.1%
C116 received was 33pF 16v C0G 1206 and should be 100v NP0/C0G this one needs to be replaced, as the low voltage rating may cause distortion when driving at higher voltages.
The two values R104/106 are needed to be precise 0.1% tolerance to tweak the output DC offset as close to 0mV as possible if running DC coupled mode. If you will be running AC coupled mode it won’t matter. Also, until one takes all the variations on the DC offset path, it may not matter as the voltage drop across the transistors also come into play. It’s not a big problem - and it will still work fine. You may get 15mV offset but that may not matter anyway.
For the output coupling cap, I spec’d a 47uF electrolytic. For those of you intending to drive the Edcor on the M2X, that’s a 600ohm load, so something like 220uF would give deeper bass flat to 5Hz vs 20Hz as you would have for 47uF. I picked the Nichicon Muse series 220uF 50v (UKZ1H221MHM) for this. It’s a bit big and will have to stand up kind of high to clear the other parts or you might even try 100uF which is smaller diameter. Although the 47uF will sound just fine too unless you are trying to listen to home theater rumble.
Otherwise the Shopping Cart above is fine.
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Looking at Vunce's saved Mouser cart, some of the items selected are showing on back order and not currently available, one of the items is showing as a long lead time, so another alternative may need to be chosen.
Maybe Vunce, when you edit the cart based on X's changes, you might want to look at the BO items as well - just a suggestion, as I am sure members might want to order parts for their build.
Maybe Vunce, when you edit the cart based on X's changes, you might want to look at the BO items as well - just a suggestion, as I am sure members might want to order parts for their build.
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