MOX-like crossover and discrete opamp group buy - diyAudio
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Old 12th April 2004, 02:34 PM   #1
tiroth is offline tiroth  United States
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Location: Pittsburgh, PA, USA
Default MOX-like crossover and discrete opamp group buy

About
This is a group buy for a MOX-like adjustable active crossover based on moamps' original project. Jens' Rasmussen has done a layout for this project using DIP8 opamps.
The page for the filter board is here

There will also be a group buy on discrete opamp PCBs, also based on moamps' design. The PCB for the opamps will be finalized in the next 24-48 hours. The final design will be able to replace standard dual opamps in other circuits, although a resistor to ground is needed for DC stability.
The thread for the discrete opamp layout is here.

Features
Each board contains some buffers, low pass and high pass sections, and adjustable gain. Corner frequency and filter Q are independently variable, and 1st or 2nd order filters can be realized with a single board, or higher order with additional boards.

The boards are single ended or balanced inputs and single ended outputs. There is a prototyping area on the boards so that you can easy add EQ, additional filter stages, balanced out, etc. You can use the discrete opamps that are part of this buy, or you can use any FET-input opamp of your choice such as OPA2134.

Boards needed for common configurations, stereo
1st/2nd order 2-way: 2
1st/2nd order 3-way: 4
3rd/4th order 2-way: 4
3rd/4th order 3-way with 2nd order BP: 6

If you need a lot of outputs at high order and want to use less boards, you might buy enough boards to prototype one channel, and then hard-wire some additional filters.

How to order
The cost will be no higher than this:
MOX board: $7
Set of 8 discrete opamp boards: $5


I hope these prices will go down dramatically, but it depends on the level of interest.

Please sign up at the Wiki!

There will be two phases. First, I'd like people who are interested to sign up at the Wiki above. Let me know how many boards you would like--do not send any money yet! Once I know the level of interest, I'll set the price and accept payment.

Please let me know anything I've missed. I will accept PayPal and ship worldwide; shipping is $5 for any number of boards in the U.S., should be similar for Canada, and I will post the cost to other countries as sign-ups come in.

Thanks,
Tyler
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Old 13th April 2004, 01:48 AM   #2
tiroth is offline tiroth  United States
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Updated opamp PCB. Can be used singly as SIP-6 or two together as dual DIP8 replacement. I'd welcome comments in the opamp thread.

Eight of these are included for $9; I'd like to get this price down to $4-5 but will depend on the number of orders. Please sign up in the wiki!
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File Type: gif mox.gif (10.1 KB, 4280 views)
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Old 13th April 2004, 08:53 AM   #3
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How many board's do I need for 1 lowpass (subwoofer) filter?
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Old 13th April 2004, 12:17 PM   #4
tiroth is offline tiroth  United States
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Tazzy,

A single board is all you need for 1st-2nd order low pass. Strictly speaking, you would need a pair to get up to 4th order. This would also give you a high pass output for crossing to your mains or satellites, if needed.

Andypairo,

I saw your comment about balanced. The board supports balanced input. There isn't circuitry to support balanced out, but that could easily be added with a single DRV134 in the prototyping area, or a couple of opamps if you want to do it "manually". This is what the prototyping area is for! Does that work for you?
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Old 13th April 2004, 12:34 PM   #5
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I hadn't paid too much attention at the veroboard-like area on the PCB image, I think that it will be good for the purpose.

Cheers

Andrea
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Old 14th April 2004, 01:46 AM   #6
tiroth is offline tiroth  United States
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Another opamp PCB update.

Please sign up at the wiki if interested! I have almost enough commits to lower the prices.
http://www.diyaudio.com/wiki/index.php?page=Moxbuy
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File Type: gif mox.gif (20.6 KB, 3968 views)
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Old 14th April 2004, 03:49 AM   #7
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Wow! That board is over 1 square meter!
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Old 14th April 2004, 03:14 PM   #8
tiroth is offline tiroth  United States
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Default Price drop!



Okay, there is enough interest to move forward. I hope to have the protos by the weekend after next. The following week (week starting 26 April) I will plan on freezing the price. I'll then accept payments and new orders for a week, but the price will not change. I'll accept delivery 4 weeks later (cheapest) and ship out immediately. Please email me if there are any concerns about timing.

Contact me now if you know you can't pay by paypal!

I'm also trusting to fate that there are at least 15 new orders because:

Price drop!
MOX: $7
Opamp set: $6
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Old 14th April 2004, 04:11 PM   #9
troystg is offline troystg  United States
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Default I'm in on the purchase

Hi-

I am new to this forum, and for some reason I have not been able to figure out how to sign up for this buy on the wiki page.

I would most certainly like to purchase some boards but at this time I have not been succesful in figuring out how.

Pointers for the blind(figuratively)?

Thanks, Troy
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Old 14th April 2004, 04:43 PM   #10
tiroth is offline tiroth  United States
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No problem. Just go here

http://www.diyaudio.com/wiki/index.php?page=Moxbuy

and scroll all the way to the bottom. You'll see a large link called "Click here now to edit this WikiPage". Click it, and you'll see a textbox with the entire text of the page in it. Scroll to the bottom of that, and you'll see the table laid out like this

||Name||1||2||3||4||USA||Comment||

Just pick a blank line and insert your info where the spaces are.

|| || || || || || || || -> ||rabstg||0||0||0||0||USA|| ||
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