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
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
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?
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?
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
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
Attachments
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
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
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
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
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|| ||
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|| ||
I just came upon this post and found it interesting in that if I'm to understnd youv'e developed a pin for pin replacement of IC based OPAMPS in other words these can drop into typical 8pin single or dual locations being all things equal I'm curious can these replace for example a OPA627 opamp
jhead,
This IS a generic opamp replacement, with two caveats
1. you need a 4k7 resistor from the output to ground somewhere; that means either connecting the ground pad on boards or adding this resistor to the mainboard.
2. all opamps have different specs, but for the majority of audio applications this discrete should be great.
You might want to read moamps' response in the opamp thread; while he didn't directly compare them, he said that he expects the discrete opamp to be more to his liking than something like OPA627.
This IS a generic opamp replacement, with two caveats
1. you need a 4k7 resistor from the output to ground somewhere; that means either connecting the ground pad on boards or adding this resistor to the mainboard.
2. all opamps have different specs, but for the majority of audio applications this discrete should be great.
You might want to read moamps' response in the opamp thread; while he didn't directly compare them, he said that he expects the discrete opamp to be more to his liking than something like OPA627.
Manual - first edition
Hello,
I uploaded the first edition of the filtermanual.
http://www.delta-audio.com/Active_Filter_Two/Active filter two ver 1.0 manual temp.pdf
\Jens
Hello,
I uploaded the first edition of the filtermanual.
http://www.delta-audio.com/Active_Filter_Two/Active filter two ver 1.0 manual temp.pdf
\Jens
jhead, I suggest you post in the opamp discussion thread. What you ask for is certainly possible, but maybe some changes to resistor values are needed depending on the drive current required. Since MPSA92 can handle 500mA, not a problem. But the biasing may differ depending on the impedance of your headphones.
But the biasing may differ depending on the impedance of your headphones.
A request
A request to those who have different amounts of opamps in the $6 and $5 columns in the wiki: the proportion of MOX boards to opamp sets differs significantly depending on the column. I need to make a decision about how to panelize the order by Monday morning, so I need to have a better idea about how many opamp boards people want given that the price has fallen 33%.
If you signed up when the OPA boards were $9, and would now buy more at $6, please update the wiki
My thanks to anyone who takes the time. I am not ruling out a drop to $5, and in fact having more "confirmed" orders makes this more likely.
I will post pics of the protos when the arrive. Thanks!
A request to those who have different amounts of opamps in the $6 and $5 columns in the wiki: the proportion of MOX boards to opamp sets differs significantly depending on the column. I need to make a decision about how to panelize the order by Monday morning, so I need to have a better idea about how many opamp boards people want given that the price has fallen 33%.
If you signed up when the OPA boards were $9, and would now buy more at $6, please update the wiki
My thanks to anyone who takes the time. I am not ruling out a drop to $5, and in fact having more "confirmed" orders makes this more likely.
I will post pics of the protos when the arrive. Thanks!
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