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O2 Amplifier Kit & PCB Groupbuy, Worldwide

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Since the first GB is in the last stages and there is not much work left with it, the second installement can begin.
I know the following text is long and I am sorry for this. Please read every paragraph.
That answers most questions and provides a clear guideline for you to place an order.
The last GB was offered as a service to this community in the same spirit as RocketScientist invented it.
This time around, I need to be able to justify the significant time put into this.
The prices have therefore been increased a little to reflect the time and effort from my side.

THE O2 COMPONENT KITS: 25€ per kit
The O2‘s creator, RocketScientist, provides the BOM via his Blog NwAvGuy.
I have used his latest BOM with no modifications.
His BOM does list alternatives. These will be used if, and only if, the first choice parts are unavailble.
All resistors listed under „Gain Resistors“ are included for ease of handling and your convenience.

This also means there are NO 9V batteries included, as these are prohibitet from standard AirMail.
The kit also includes NO transformers, NO enclosures, NO printed circuit boards, NO low-power Op Amps, NO „Desktop O2“-parts and NO solder/wick.
Except for the batteries, the other parts are available to you through this GB.

It is NOT possible to order a kit and replace the pots or with only a certain type of gain resistor.
This would increase the workload for me by a significant amount and only save you pennies.
Additional parts are available as „extras“ via the section labeled „extras“ below.
You can therefore order a component kit and then buy a different pot as an „extra“.

THE TRANSFORMER: 25€ per transformer
A custom transformer is made for this GB from a company in Europe.
This ensures a high quality transformer according to european laws and regulations, no questionable chinese copy.
(I don‘t claim all chinese parts are bad, but I can‘t very well reach or control a chinese manufacturer.)
Since this transformer can only be ordered in larger batches, we need at least 30 orders on these.
It is a 230V transformer and not suitable for countries with deviating power grid voltages.
A picture of it can be found in my signature.

THE ENCLOSURE: B2=20€ / B3=22€ per enclosure
The O2‘s PCB has dimensions of 80x100mm‘s, so all enclosures for this size of board will fit.
As in the last GB, I provide a possibility to purchase one type of extruded aluminium enclosure.
It is available in different colors (black/silver/red/blue/green).
The standard height (B2) is sufficient for the standard set of components.
However, it is also available in a taller version (B3).
Pictures can be found in the gallery in my signature to help you choose a size and color.

A high-quality PCB is also available for your convenience.
I will order them in larger batches directly from a known and reliable source.
They are the same guys that manufactured the PCB‘s for Ollie‘s O2 PCB group buy that many people used.
The PCB will feature black soldermask, white silkscreen (the writing on the PCB), electroless gold plated contacts and FULL e-testing.
This ensures only first class boards are produced and shipped to you.
You can see a picture of an identical circuit board in the gallery in my signature.

THE SHIPPING: As listed below
By default, I will ship all orders with the Deutsche Post / DHL.
Included in the shipping costs below are the packaging (padded envelope) and ESD bags for all kits.

up to 500g : 5€
up to 1kg: 8€
up to 2kg: 10€
up to 500g: 5€
up to 1kg: 10€
up to 2kg: 18€

Shipments above 2kg are not available, they have to be split and will incurr multible shipping charges.
(It is possible via Deutsche Post / DHL / FedEx / UPS, but more expensive than multiple shipments.)

At your discretion, shipping with FedEx and UPS is possible.
Be advised that FedEx/UPS are only shipped once a week and may add significant cost to your order.

THE EXTRAS: cost as listed by Mouser/Farnell
I will order all the parts from Mouser and Farnell (except custom transformers and custom PCBs).
For your convenience, you will be able to order any parts from these two companies through me.
However, I will not process an order for extras if it contains 90% of a component kit.
This has happened before (where I did not forbid it, so no blame) and I spent 40 minutes on one order.
Also, no volume discounts will be given for extra parts, even if multiple people order the same components.
This is meant as a service to you, please do not exploit it with large orders that would be better placed with Mouser/Farnell directly.

Please provide any extras in the following format:
(Quantity)x (space) part number from dealer (space) (Mouser)or(Farnell).
1x 568-NYS367-2 (Mouser)
3x 577-1810-5F (Mouser)

Popular extras from Mouser are solder and wick. Here are their part numbers:
Solder: 590-4890-18G
Wick: 577-1810-5F


Is possible via PayPal ONLY to ensure I am notified of any incoming funds immediately.
Screening my bank account for incoming payments and linking them to orders is too time-consuming.
I have done a market analysis, but unfortunately there are no fully working crystal balls available.
Therefore, to be able to link payments to orders, I need your real&forum names in the PayPal payments.
Also, please send an eMail to the PayPal address that includes both your forum name and your address.
It is very important you provide the address in the format you wish me to write on the envelope.
If your country writes the city before the ZIP-code, write the city before the ZIP-code in your eMail.
I will photograph all outgoing shipments with timestamps and geotags to be able to prove shipping.
But if the mail company in your country can‘t compute your address because it was provided to me in the wrong format; then I will not be able to issue a refund or a second shipment without charge.

(In case you wonder about all the capital letters, 40% of the people in the last GB failed to do this, causing me several hours of, completely unnecessary, work. So please excuse me for being extra clear on this.)

I can be contacted via PM and email (see PDF in my signature).
However, I want to ask you to place your orders only in this thread.
That makes it easy for me to find them and others can follow what happens.
I will then put your forum name in the PDF, where it will automatically display the amunt you owe.
THEN, and only then, you can send the money via PayPal. Please wait to be included in the PDF.
Sending money before placing a confirmed order does not speed up the process, it slows it down. A LOT.

If there are any questions, please feel free to ask them in this thread.
And thank you for reading throug all of this. I know it is a pain.
But this is the only way to keep the amount of work to an acceptable level for me.
Otherwise I would not be able to offer you a way to purchase the parts you desire.

And now, there is only one thing left to say:
Gentlemen, start your engines!
Last edited:
Hah, perfect...
The first person that reads my entire post and orders accordingly and I immediately find a mistake in my post:
If you actually care about the color of your enclosure, please don't forget to list the color.
All other enclosures will automatically be black (the most popular color from the first GB).


P.S.: The new order PDF will be up and running later today.
First I need to thank you for your hard work on make the group buy. I really appreciate your efforts on this amazing project! I waited this second GB to start and now you make me very happy! Thanks!
Now my order:
1x kit
1x transformer
1x enclosure B2 (blue)
1x 590-4890-18G (Mouser)
(shipping to italy)

P.S. NwAvGuy have recentely changed R25 & R9 (see NwAvGuy: O2 Details )
the standard kit will have this change or not?
The kits will always feature the most up to date BOM at the time I place the order.

I have asked him and there will be no PCB-change in the immediate future.
-> PCBs are the only thing I buy in larger volumes up front, but all component kits will fit perfectly.
(This reduces the cost and has no disadvantages. After all, PCBs have no expiry date.)
And as a big surprise, I have ordered some red/blue/white/yellow PCBs as well.
If they turn out gorgeous, they will be available for a small price premium.
(Order quantity on those is much smaller, so the prices for manufacturing are much higher.)
And I just ordered 1000€ worth of PCB's.
So, if anybody needs boards: I got spares :)
They are set to arrive within 20 working days from today.
(12 instead of 20 days would have increased costs by 50%... just not worth it.)

The hippie-boards (Red, Blue, Yellow, White) will be available for 20€ a piece via the extras.
If demand for these is high enough to justify another production run, costs will be lower.
But for now, anybody with acrylic cases or a sense for exclusivity: Get 'me while they're hot.

And because I was asked a good question: No, you do not HAVE to order a kit.
It is entirely possible to order just a transformer, just a case or any combination.
The only exception being the extras: If you want any of those, I'd ask you to order them with at least one of the other items as I don't earn anything on extras or shipping.

Best regards,
Many thanks Jokener, Please put me on the list for:

2x kit
2x B2 red
2x 595-OPA2277PA (mouser)
4x 595-TLE2062CP (mouser)
2x 450-BA161 (mouser)
4x 806-STX-31205B701C (mouser)
4x 806-STX-31205B (mouser)
4x 611-G003R (mouser)

The extra's should result in red buttons and red terminals for the red case. With a black input terminal as backup if pink is really to pink :)
@McTavish: You sure about the green?
I had initially ordered one for myself and don't like the color at all.
Of course I'd be happy to sell you a green case.
Just want to make sure I make you a happy panda, not a sad panda.

@all others: You're in the new spreadsheet.
I just have to completely rewrite the shipping matrix because I changed the shipping cost.
(Only three weight categories, the old matrix went up to 31.5kg which doesn't make sense.)
I hope to finish the re-write today to upload it for you to check.

Best regards,
Okay, so the new spreadsheet should be up and running.
I did not yet have a chance to check the Mouser prices on the extras.
Also, since I am writing this on an iPad, I have to admit I don't recognize the flag for CeeVee.
(There is no mouse-over on an iPad...)

So please don't pay yet if you have any extras, I will update the spreadsheet later today.

Best regards,
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