• These commercial threads are for private transactions. diyAudio.com provides these forums for the convenience of our members, but makes no warranty nor assumes any responsibility. We do not vet any members, use of this facility is at your own risk. Customers can post any issues in those threads as long as it is done in a civil manner. All diyAudio rules about conduct apply and will be enforced.

Active filter board GB

Status
Not open for further replies.
Jump to Latest
#382
Bill,

The filter outputs are buffered, so the output impedance is ~100R or whatever you choose for the output resistor. Your amps' impedance should not affect the frequency response.

3 boards per 4 way is correct - so 6 for stereo. If you are planning 6 dB/octave for the tweeter, you could just use a cap and eliminate one filter board per channel. I've never been a fan of first order slopes - Linkwitz's argument for 12 dB electrical minimum makes sense for me.

If you are using a single sub/ mono subs you could use the buffered outputs to feed a single subwoofer filter board, so you could get by with 5 boards.

I recommend two power supplies if you use 5 or 6 boards.

Bob
 
#383
== Buy 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 or link below, click on "Purchase Boards and Parts". 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.
 
#385
And I thought I took a while to get back to it. ;-)

Vaction was quite relaxing - 20 minutes in Lake Champlain would keep me cool for a couple of hours, despite the heat. Had some nice hiking, too.

We hit 100F today. Hi-Low thermometer I left in the car said it hit 158F. It felt almost cool when it got down to 120 or so.
 
#386
We hit 97 last week.Off course with a high humidity.On top of that the aircon in my car gave up the ghost.A 1,5 hour drive to work suddenly seems a lot longer.All repair shops have a 3,5 week waitinglist.

How many miles did you hike? In those temps it seems more of a punishment than good fun.

kro5998
 
#388
Somewhere on this board is a thread (or three) about the virtues and vices of various opamps. There seemed to be a general consensus that the OPA2604 was a bit dark sounding. Most preferred the OPA2134 or OPA2132 if going TI duals.

Many preferred the LM6172 - it is a significantly faster chip. That could cause problems with instability. I am not aware of anyone using them on this board, but my gut tells me it will work as long as the Q/gain setting resistors are bypassed with 100-200 pF as provided for on the board. I'd stay away from the really high speed SMT chips on adapters, though.

Many think the venerable NE5532 sounds fine. I haven't built anything with my OPA2134s yet, but I have no complaints about my NE5532s without hearing anything "better". It's probably better suited to driving low impedance loads than the OPAs, since it was designed as a 600 ohm line driver.
 
#391
The buy closes on August 18th.

Boards should be available a couple weeks later, as Advanced Circuits is offering 2 week delivery at the 4 week price. I should be able to get the boards and kits shipped in early September.

In case anyone was wondering, we are up to 125 filter boards and 50 PSU boards (26 kits)

/Bob
 
#397
Will filter behave according to theory?

Hi Guys,

At last I have time to get along with the filter.
I have a design ready now that fits the design goal nicely.
I compare the output with the design curve using 5Spice.
My question: will the real world filter give the output as predicted by 5Spice?
I don't use the specific spice model for the OPA 2134 but the standard as used in 5spice. Will it make a difference?
Anyone having experience with this point?

By the way: the design uses only one opamp per stage and does not use the buffer Jens has incorporated on the board. Decreasing the number of opamps used seems a good thing as long as the filter will behave correctly.

Thanks
Dick.
 
#398
Dick, depending on how you compensate for the gain of each stage (if you leave it as an equal component value filter) there may be some differences in predicted/actual response without the buffer. I have run stages with gain of 2 directly to a line buffer, without issues. However, if the load is another filter you may run into differences.

BTW, if you mod the AF4 circuit this way, be sure to ground the un-used half of each op amp's inputs to avoid oscillation/interaction problems.
 
#399
Hi Bob,

I use all filters with a gain of 1.
In the input buffer I plan to use 6 dB gain.
Will this be enough to drive a power amp?
I plan to drive the filter directly from the source and control the volume after the filter (or perhaps rather just before the output buffer).

Dick.
 
#400
So R14 is jumpered? Then you should have no problem and simulation should match reality. You can take your output from one of the C11 pads and having the + input of the unused buffer connected to the output of the filter should keep it quiet without affecting the signal.

You should have plenty of signal with 6 dB gain in the buffer with most sources (CD player, etc.)
 
Status
Not open for further replies.
Top Bottom