These boards make a completely analog single channel two way/bandpass active crossover with several EQ options. I have not listened to the Behringer, so I cannot comment on sound quality. With good opamps and sound component choices you should have at least equal sound quality.
Linkwitz suggests that for dipole use digital crossovers might not be up to the task in terms of dynamic range and processing power.
The notch filters can make virtually any depth notch in one stage, as opposed to the ~15 dB limit per notch of the Behringer (for a 40 dB notch you'd use 3 notches at the same frequency). A notch such as used making a Cauer-Elliptic filter would use a lot of the Behringer's processing power. However if you are simply notching out a large breakup mode, 15 dB is usually enough.
Note that you will need multiple boards for most applications- 2 for a stereo 2 way, 4 for 3 way or 2 way plus sub, 6 for a 4 way. Also, this board is not designed as a prototyping board, rather it is a platform to build your final product. Not that changes can't be made, but ease of repeated adjustment was not a design goal and you'll have to desolder parts to change values.
Linkwitz suggests that for dipole use digital crossovers might not be up to the task in terms of dynamic range and processing power.
The notch filters can make virtually any depth notch in one stage, as opposed to the ~15 dB limit per notch of the Behringer (for a 40 dB notch you'd use 3 notches at the same frequency). A notch such as used making a Cauer-Elliptic filter would use a lot of the Behringer's processing power. However if you are simply notching out a large breakup mode, 15 dB is usually enough.
Note that you will need multiple boards for most applications- 2 for a stereo 2 way, 4 for 3 way or 2 way plus sub, 6 for a 4 way. Also, this board is not designed as a prototyping board, rather it is a platform to build your final product. Not that changes can't be made, but ease of repeated adjustment was not a design goal and you'll have to desolder parts to change values.
== Underway - closing date 18 August ==
To simplify my record keeping and try to improve accuracy, I've set up a PayPal shopping cart for purchase of boards and kits. You can use a credit card even if you have no PayPal account. If you don't have a credit card, email me to make arrangements.
Go to http://mysite.verizon.net/vze3xvxs/audio/id19.html. Click on the "add to cart" buttons as desired. You can increase the quantities in the cart.
Be sure to select a shipping option. In the US, most orders will fit in the Priority Mail envelope. Outside the US, I can fit 10 boards or 6 boards and a power supply kit into a small GPM envelope. Small quantities of 100 nf will fit as well. If you have more than one PSU kit, you'll need the large envelope for up to 4 psu kits. If in doubt, email me and I'll figure out shipping cost.
Pricing:
Filter Boards $5
PSU Boards $6.25
PSU Kit $28 (includes board, parts and heat sinks)
I also will offer 470 uF Panasonic FCs for the filter boards (2 required per), 100 nF/100V Epcos Film caps for decoupling, 1500 uF 35V Panasonic FCs and BC546C/BC556C.
To simplify my record keeping and try to improve accuracy, I've set up a PayPal shopping cart for purchase of boards and kits. You can use a credit card even if you have no PayPal account. If you don't have a credit card, email me to make arrangements.
Go to http://mysite.verizon.net/vze3xvxs/audio/id19.html. Click on the "add to cart" buttons as desired. You can increase the quantities in the cart.
Be sure to select a shipping option. In the US, most orders will fit in the Priority Mail envelope. Outside the US, I can fit 10 boards or 6 boards and a power supply kit into a small GPM envelope. Small quantities of 100 nf will fit as well. If you have more than one PSU kit, you'll need the large envelope for up to 4 psu kits. If in doubt, email me and I'll figure out shipping cost.
Pricing:
Filter Boards $5
PSU Boards $6.25
PSU Kit $28 (includes board, parts and heat sinks)
I also will offer 470 uF Panasonic FCs for the filter boards (2 required per), 100 nF/100V Epcos Film caps for decoupling, 1500 uF 35V Panasonic FCs and BC546C/BC556C.
Bob, Jens, could you just clarify something for me?
I'm just getting used to the topology you used to set your high and low pass filters, as you know it's a little different to the format Rod uses for LR and I'm just trying to get my head round it.
High pass is simple enough, for example, if C3/4= 10nF then C11 is 20nF, and if R6/7/14=10K then R19=17K5.
But for the Low Pass, am I right in thinking that C14/15/21 are all 20nF, R25/26 are 10K, R29 is 20K, and R36 is 35K?
It would be really valuble if you could put values on the components in the worked examples given in the manual rather than just designators.
I'm just getting used to the topology you used to set your high and low pass filters, as you know it's a little different to the format Rod uses for LR and I'm just trying to get my head round it.
High pass is simple enough, for example, if C3/4= 10nF then C11 is 20nF, and if R6/7/14=10K then R19=17K5.
But for the Low Pass, am I right in thinking that C14/15/21 are all 20nF, R25/26 are 10K, R29 is 20K, and R36 is 35K?
It would be really valuble if you could put values on the components in the worked examples given in the manual rather than just designators.
Hi Al,
This is the Sallen-Key equal component value topology. C11, C12, C21, C22 are intended to be bandwidth limiters - around 100 to 220 pF. This will bring the gain of the section to unity at high frequency. The four components attached to the + input are the frequency determining components. An advantage of this topology is you don't have to find precision caps that are available in twice the value of your primary cap or double them up for the low pass section when you want LR4 response.
Using your example values, 10 nF and 10K, you get a cutoff frequency of 1591 Hz. The Q is set by the ratio of R14 to R19. For a LR4 electrical response, each filter section must have a Q of .707. This gives R19 of 17K for R14 at 10K.
You can use Rod's calculator for LR4 (and have the same topology) by jumpering R14 and omitting R19 and C11 (or equivalent in the other sections).
For an LR2 electrical response, set Q=.5. This means you leave R19 open and you can jumper R14 or choose the value for lowest DC offset (equal to the parallel equivalent of R6 and R7).
Don't forget that a Linkwitz-Reilly electrical response doesn't necessarily mean that you'll end up with L-R acoustic response. I'm pretty sure you know this Al, it's for the relatively new guy's benefit. For example a Q=.7 natural acoustic rolloff combined with a Q=.707 second order electrical filter at the same frequency will result in an LR4 acoustic sum. You wouldn't use an LR2 electrical response, even though the filter is only second order.
An update of the manual is on my to do list. Do you mean that you'd like to see the schematic in the examples annotated with C3/10 nF, R6/10K, etc?
I put together a spreadsheet for determining component values for those who just want the values without caring how they are derived. There is a link to where I posted it on the Wiki and it is on my web page Here
This is the Sallen-Key equal component value topology. C11, C12, C21, C22 are intended to be bandwidth limiters - around 100 to 220 pF. This will bring the gain of the section to unity at high frequency. The four components attached to the + input are the frequency determining components. An advantage of this topology is you don't have to find precision caps that are available in twice the value of your primary cap or double them up for the low pass section when you want LR4 response.
Using your example values, 10 nF and 10K, you get a cutoff frequency of 1591 Hz. The Q is set by the ratio of R14 to R19. For a LR4 electrical response, each filter section must have a Q of .707. This gives R19 of 17K for R14 at 10K.
You can use Rod's calculator for LR4 (and have the same topology) by jumpering R14 and omitting R19 and C11 (or equivalent in the other sections).
For an LR2 electrical response, set Q=.5. This means you leave R19 open and you can jumper R14 or choose the value for lowest DC offset (equal to the parallel equivalent of R6 and R7).
Don't forget that a Linkwitz-Reilly electrical response doesn't necessarily mean that you'll end up with L-R acoustic response. I'm pretty sure you know this Al, it's for the relatively new guy's benefit. For example a Q=.7 natural acoustic rolloff combined with a Q=.707 second order electrical filter at the same frequency will result in an LR4 acoustic sum. You wouldn't use an LR2 electrical response, even though the filter is only second order.
An update of the manual is on my to do list. Do you mean that you'd like to see the schematic in the examples annotated with C3/10 nF, R6/10K, etc?
I put together a spreadsheet for determining component values for those who just want the values without caring how they are derived. There is a link to where I posted it on the Wiki and it is on my web page Here
Gotcha. That makes perfect sense now you've broken it down. I was having a wood/trees perceptual glitch I think! The application I'm using the PCB for is actually a LR4 bandpass for a sub, at 20 and 80Hz, I just used those component values for illustrative purposes as the math was more obvious.
As for the schematics in the manual, that's exactly what I meant. For instance, If I looked at your 2 way example with the LR4 crossover, and seen that C11/12/21/22 were all 100pF, it would probably have clicked that they were all compensation caps and not part of the frequency shaping.
Just downloaded the spreadsheet, that makes everything so much more straightforward
As for the schematics in the manual, that's exactly what I meant. For instance, If I looked at your 2 way example with the LR4 crossover, and seen that C11/12/21/22 were all 100pF, it would probably have clicked that they were all compensation caps and not part of the frequency shaping.
Just downloaded the spreadsheet, that makes everything so much more straightforward
Killjoy
Sorry - I was just posting updates in the group buys thread.
Boards will be delivered to me next week, and I will begin shipping shortly afterwards.
samsagaz
There were a few repeat buyers, so I assume they are happy with the crossover design.
The PSU was offered as a kit since most will be doing the same thing with it. I figured everyone would be doing something different with the XO so a kit didn't make sense. It was just a bare board with guidance in the form of a spreadsheet and manual.
I ordered 50 extra boards but all are spoken for. Maybe if there is a round four...
Sorry - I was just posting updates in the group buys thread.
Boards will be delivered to me next week, and I will begin shipping shortly afterwards.
samsagaz
There were a few repeat buyers, so I assume they are happy with the crossover design.
The PSU was offered as a kit since most will be doing the same thing with it. I figured everyone would be doing something different with the XO so a kit didn't make sense. It was just a bare board with guidance in the form of a spreadsheet and manual.
I ordered 50 extra boards but all are spoken for. Maybe if there is a round four...
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.