till,
Balanced in is already supported. Balanced out could be easily done using the prototyping area. DRV134 would be one option, or you could use a pair of opamp boards to create a differential driver. I will elaborate more on this later.
Peter,
Yes, each board is 1 channel. It can be used high pass, low pass, or bandpass (up to 2nd order). There is an (optional) input buffer, and up to three output buffers.
If you want to use every single filter and buffer on the board, you need four dual opamps (8 single).
But, you don't need this many in most cases. The board is a swiss-army knife; as-is, everything is buffered in and out so you don't have to think about it. But if you know your source impedance is low enough, if you don't need gain adjust, if you aren't driving a cable and have a high Z following stage, you could build this with as few as 2 opamps per board. You'd need to know what you are doing though.
A simpler answer is you need 5 (input buffer, HP filter+buffer, LP filter+buffer) opamps per board, 4 if the board is piggy-backing off of the input or ouput buffer on a another board.
Here is the listing again for the number of boards required for common configurations. Let me know if you'd like me to elaborate on how it would be done.
Balanced in is already supported. Balanced out could be easily done using the prototyping area. DRV134 would be one option, or you could use a pair of opamp boards to create a differential driver. I will elaborate more on this later.
Peter,
Yes, each board is 1 channel. It can be used high pass, low pass, or bandpass (up to 2nd order). There is an (optional) input buffer, and up to three output buffers.
If you want to use every single filter and buffer on the board, you need four dual opamps (8 single).
But, you don't need this many in most cases. The board is a swiss-army knife; as-is, everything is buffered in and out so you don't have to think about it. But if you know your source impedance is low enough, if you don't need gain adjust, if you aren't driving a cable and have a high Z following stage, you could build this with as few as 2 opamps per board. You'd need to know what you are doing though.
A simpler answer is you need 5 (input buffer, HP filter+buffer, LP filter+buffer) opamps per board, 4 if the board is piggy-backing off of the input or ouput buffer on a another board.
Here is the listing again for the number of boards required for common configurations. Let me know if you'd like me to elaborate on how it would be done.
Manual - second edition
Hello,
I uploaded the second edition of the filtermanual.
http://www.delta-audio.com/Active_Filter_Two/Active filter two ver 1.0 manual temp.pdf
Please comment - thanks
\Jens
Hello,
I uploaded the second edition of the filtermanual.
http://www.delta-audio.com/Active_Filter_Two/Active filter two ver 1.0 manual temp.pdf
Please comment - thanks
\Jens
sorry, i´m not that bright as Peter, i still don´t really understand. The number of opamp boards needed also depends on the impedances to drive? So what do i need for low impedance source, balanced, 2way 2nd order, balanced out, low impedance power amplifier (SOZ) to drive? 2MOX and how many opamps? my motivation would also rise some higher if balanced out would be implemented on the PCB allready.
Would it be possible to send cash instead of paypal?
What about euopean or german sub-grouporder to simplifiy money and boards transfer?
Would it be possible to send cash instead of paypal?
What about euopean or german sub-grouporder to simplifiy money and boards transfer?
Till,
If we start splitting up the group order, the price will not be as low as if we all order together.
Regarding the number of opamps it is not depending on the impedance you want to drive. If you use opamps like the OPA2134 I doubt there will be any problems since it can deliver something like 50 mA.
However the question remains if the discrete opamp will drive difficult loads?
A complete filter board needs 4 dual opamps or 8 discrete single ones. However when you use the board, there are several configurations where not all opamps are needed – take a look at the filter page and schematics and consider what setups you need. It all depends on what filter order you need and if it’s a two, three or four way system you plan to make.
I don’t think the board is going to change – if you want balanced out, I suggest you use the prototype area on the PCB for that purpose. The reason being that balanced out can be made I so many different ways that it would be impossible to make everybody happy.
We had enough trouble finding out what configuration to make in the first place
\Jens
If we start splitting up the group order, the price will not be as low as if we all order together.
Regarding the number of opamps it is not depending on the impedance you want to drive. If you use opamps like the OPA2134 I doubt there will be any problems since it can deliver something like 50 mA.
However the question remains if the discrete opamp will drive difficult loads?
A complete filter board needs 4 dual opamps or 8 discrete single ones. However when you use the board, there are several configurations where not all opamps are needed – take a look at the filter page and schematics and consider what setups you need. It all depends on what filter order you need and if it’s a two, three or four way system you plan to make.
I don’t think the board is going to change – if you want balanced out, I suggest you use the prototype area on the PCB for that purpose. The reason being that balanced out can be made I so many different ways that it would be impossible to make everybody happy.
We had enough trouble finding out what configuration to make in the first place
\Jens
FAQ
I'll answer your questions, till, as well as some that keep coming up over and over.
Does not support balanced out directly, but can be added with a single DRV134 or use a pair of opamp boards as a differential driver. More on this later. Don't forget that there is an on-board prototyping area for this purpose!
You also need 1 DRV134 and be willing to do some extremely simple wiring in the prototyping area.
I'll answer your questions, till, as well as some that keep coming up over and over.
No. The proto order is already out, which means any changes will incur a tooling fee. That means changes will be made only if some error is found.
Supports balanced in (and single ended).
Does not support balanced out directly, but can be added with a single DRV134 or use a pair of opamp boards as a differential driver. More on this later. Don't forget that there is an on-board prototyping area for this purpose!
No! But, your understanding of the impedances and kinds of circuits involved may allow you to eliminate some of the opamps to save costs and space.
I would really like to discourage this for many reasons, but I'm happy to discuss by email. I will work something out for people who truly cannot pay via Paypal.
I'm definitely happy to accomadate sub-orders if it will help you save on shipping and transfer fees. (You will need at least a few people involved to actually save anything, I'd think) If you are stepping forward just indicate in the wiki that you would like to coordinate, and/or get in touch with the other people ordering from your country.
Some tests will be shown before going to production and accepting orders. I don't expect any issues though as I am currently driving ~12' balanced lines from FETs with an even higher output impedance in my active XO.
You can't go wrong if you start with 4 dual monolithic opamps per board. If you really want the discretes, buy 1 set per board and only build the number you end up needing. I recommend that only experienced builders consider building with <8 opamps per board, because you must have a good understanding of the entire circuit to know which ones can be eliminated. Or be building from someone else's instructions. There are so many scenarios that I am at a loss to explain them all, but I did make some general comments previously.
Yes, you need two MOX for stereo, and I would be tempted to use only 8 opamps total. Following my previous advice though, get two sets of discretes if you really want them, and build it with four dual monolithic opamps first. You must understand the circuit to eliminate parts.
You also need 1 DRV134 and be willing to do some extremely simple wiring in the prototyping area.
Price drop
I've lowered the cost of the opamp sets to 8/$5 and eliminated the extraneous wiki column.
Peter Daniel--you had 10@$6 and 4@$5...I guessed that you meant 4 additional, so I put 14 in the wiki. If this is incorrect, my apologies.
Randytsuch, I got your email and added you to the wiki.
I've lowered the cost of the opamp sets to 8/$5 and eliminated the extraneous wiki column.
Peter Daniel--you had 10@$6 and 4@$5...I guessed that you meant 4 additional, so I put 14 in the wiki. If this is incorrect, my apologies.
Randytsuch, I got your email and added you to the wiki.
Brian, it is hard to say, because I panelized everything together to save on costs. So, if I suddenly got 150 more mox orders (and no opamp), that might actually increase the cost to me because the ratio of mox to opamps would be severely off.
I guess I can say definitively that if there are 40 more MOX and at least 20 more OPA, I could lower the price to $6. (quite doable) I would need nearly 100 and 90 more, respectively, to lower the price to $5. We're reaching the point where 30 more orders only knocks $0.30 off per board now.
There is definitely enough leeway that DIYaudio will be receiving a donation. Perhaps I should include a "donate $1 to DIY" item in the shopping cart? (additionally, that is--for anyone that would like to)
I guess I can say definitively that if there are 40 more MOX and at least 20 more OPA, I could lower the price to $6. (quite doable) I would need nearly 100 and 90 more, respectively, to lower the price to $5. We're reaching the point where 30 more orders only knocks $0.30 off per board now.
There is definitely enough leeway that DIYaudio will be receiving a donation. Perhaps I should include a "donate $1 to DIY" item in the shopping cart? (additionally, that is--for anyone that would like to)
tiroth said:
I think that a donation would work best if built into the price. I find $1 extra per pcb is quite reasonable for both diyAudio, and the person purchasing the board. For my group order, I have donated $325 so far to the server fund. I will continue to donate more funds from the orders, once I get all the accounting settled.
I did have a "Make an additional donation" button on my order page, and only one person donated a few dollars. This caused a little bit of confusion, as another person accidentally used this button to pay for their order, which caused me confusion, as I had no record of their order.
--
Brian
You are exactly right kestrel200.
I'm including below the first draft of a "shopping list" for MOX. This is a list of all the needed parts available at Mouser (except 2SK389). I have listed both basic parts (e.g. 1% 100ppm metal film/polyester caps) and tried to list at least one alternate (e.g. Dale/Wima) for each item.
The list is split into Input buffer, MOX, output buffer, discrete opamp, and misc. The idea was to make it easier for people to separate out what they don't need.
I stress this: you don't need to fully populate the board unless you want to.
I have undoubtably made a mistake or two, and the proto order is not even in yet, so don't rush out and buy everything on this list. I would encourage feedback, and if someone feels like taking it and adding part numbers for other suppliers, that would be great. I would appreciate it if you would send it back to me though for version control.
P.S. While I welcome debate over whether there is a better part available from the same supplier, this is not intended to be an over-the-top shopping list. Welbourne labs is an excellant source for small film caps, and other specialty suppliers like Michael Percy and Parts Connexion help fill that void.
I'm including below the first draft of a "shopping list" for MOX. This is a list of all the needed parts available at Mouser (except 2SK389). I have listed both basic parts (e.g. 1% 100ppm metal film/polyester caps) and tried to list at least one alternate (e.g. Dale/Wima) for each item.
The list is split into Input buffer, MOX, output buffer, discrete opamp, and misc. The idea was to make it easier for people to separate out what they don't need.
I stress this: you don't need to fully populate the board unless you want to.
I have undoubtably made a mistake or two, and the proto order is not even in yet, so don't rush out and buy everything on this list. I would encourage feedback, and if someone feels like taking it and adding part numbers for other suppliers, that would be great. I would appreciate it if you would send it back to me though for version control.
P.S. While I welcome debate over whether there is a better part available from the same supplier, this is not intended to be an over-the-top shopping list. Welbourne labs is an excellant source for small film caps, and other specialty suppliers like Michael Percy and Parts Connexion help fill that void.
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