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Active filter board GB

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#421
filter program

Does anybody know of a computer program to try out filter frequencys / slopes / phase etc.
Using a multichannel soundcard to create a virtual 2 or 3 way filter.
I would like to experiment without having to solder/desolder the boards everytime.
You should be able to get a general idea of how a setup would sound before building the real thing.

kro5998.
 
#422
There's a foobar plug in that will make various crossovers. At last look it only did straight textbook filters, although you can spread them. It's not really a development tool, though. I haven't been able to figure out how to make it play a signal other than pre-ripped files.

Also, see the perceive construction diary thread. Shinobiwan seems to have more money in software than I have in my whole system, though.

The pro version of lspCAD (and probably others) will emulate your crossover. Another expensive tool, though.
 
#425
There are no filter boards left to sell, but there are power supply boards and kits.

Sorry for any confusion - "spoken for" is slang meaning in this case that they all are sold. I made a typical American mistake, expecting non-native speakers to understand the language, slang and colloquialisms.
 
#427
The kit is a power supply kit consisting of the board, all electronic parts (resistors, capacitors, semiconductors and screw terminals)and heat sinks needed to make nominal a +/-15V power supply. You'll need to provide mounting hardware for the supply and transistor-heat sink bolt, but otherwise all hardware is included. Add a dual 15VAC transformer of at least 30 VA and mains wiring and you have a power supply.
 
#430
F1 FAN said:

I plan on using a dual 18VAC tranny , is the extra voltage drop going to cause heat dissipation or other issues?
Click to expand...

It depends on your load. I don't think there will be any performance issues. At 18VAC nominal, you'll have around 27VDC no load given 10% regulation common in smaller size transformers. In the PSU thread I ran through the derivation of the heat load acceptable. The short version is that with 2" heatsinks inside a typical enclosure with some airflow, you can dissipate around 5W. This means at ~12 dropped you are dissipation limited to around 400 mA.

The component calculation spreadsheet I posted on my website will calculate this for you on the stated assumptions - 35C ambient, 100C max junction temperature.
 
#431
Boards have arrived

The PSU kits are kitted except boards and heat sinks (due to arrive today) I will start packing orders and expect to start shipping by Friday.

I suffered a hard drive crash yesterday. I'm glad PayPal will give me packing lists, since my backups were corrupted. All PayPal orders are fine.

If you did NOT with PayPal, please drop me a note telling me what you ordered

I think I have the few who sent checks, but I want to be sure.
 
#434
I just received the heat sinks, so I'll start packing up orders. I expect to get the first round out on Thursday morning - probably the first half of the orders or so. The rest should go out Friday or Saturday.

Believe me, I want to get all this stuff out of my living room so I can start putting together some filters, too. 😉
 
#436
NOTE FOR NON US BUYERS

If you live outside the US, I need your phone number to use the USPS customs form shipping program.

Trust me, you really don't want me hand writing your shipping label 😉

Shipping has begun. You will receive an email notifying you of your shipment when your package goes.
 
#437
The LM6172 is working!

I'm using this cross over for a few monthes.

This week I replaced the OPA2134 for the HP filter with the LM6172.

The PCB can handle the 100Mhz BW of the LM6172 without any oscillations.

I'm using 0.15uF mks4 WIMA polyester with 2.2uF tant for the supply decoupling on each Op-amp. the LM6172 is with 100pF in parallel to the feedback resistor.

Both the OPA2134 and the LM6172 sounds wery good for my hears, while the LM6172 is a bit more open in the highs.

I also tried AD825 on sockets for the buffer and didn't like his midrange sound.

Just one more note - if you are not using one of the op-amps in the dual chips - dont forget to terminate the unused circuit properly, connecting inverting input to the output and noninverting input to ground. for example, if one use the all pass section without the linkwitze transform- just jumper C20 on the board.

Thanks Bob and Jens for that great PCB and for orgenizing the group buy.

Avi
 
#438
Thanks for the info Avi. Could you explain your bypass setup a little further?

Do you have both caps in parallel on both rails? If so, I assume that you mounted one on the bottom.

Was the 2.2 uF cap necessary to prevent oscillation?

Good point on terminating the unused inputs. I think I mentioned it in the manual, but may have glossed over it.
 
#439
BobEllis said:
...Do you have both caps in parallel on both rails? If so, I assume that you mounted one on the bottom.

Was the 2.2 uF cap necessary to prevent oscillation?

Good point on terminating the unused inputs. I think I mentioned it in the manual, but may have glossed over it.
Click to expand...

The 2.2 uF Tants are on the bottom of the board
I have the tants on the board for the first place, IMO every op-amp is better to be decoupled with small polyester plus some 2.2 to 10uF Tants (polyester for preventing RF oscillations and tantalum for keeping the rail clean in audio frequencies and up to say 1 MHz.

Lately I skipped the final buffer for the HP section (IC9B), because I don't need to attenuate the HP and only the LP; I thought I can put the final buffer out from the HP board (still have the IC5A buffer and I kept the output resistor on JP8 pins 1 and 2, while disconnecting P1 and jumpering R21 to ground (in order not to leave the input of the unused final buffer disconnected).
Since I skipped the extra buffer, IC5 (LM6172) is quite hot; it could be that he oscillating above the ability of my 20 MHz scope to show, so I will increase the final resistor from 10R to 27 or 50R in order to help the fast LM6172 to drive the capacitive load.

Keeping eye on the unused op-amp is important. since I'm using the all pass section (BTW indeed linkwitz was write in saying that active filters are wroth noting without keeping the drivers phase correct - It took some time to me to test the phase of the drivers with the X-over and to align it- the change in sonic terms is astonishing 😉 )
At first I left the IC2B unused (the linkwitz transform), and I discovered that IC2 is quite hot, while the others op-amps are just warm. By jumpering C20 I have terminated the unused IC2B correctly and now IC2 is as warm as the others op-amps. unterminated op-amps can get easily into oscillations and draw more current from the supply.

Avi.
 
#440
AR_sound said:
...(BTW indeed linkwitz was write in saying that active filters are wroth noting without keeping the drivers phase correct - It took some time to me to test the phase of the drivers with the X-over and to align it- the change in sonic terms is astonishing 😉 )...
Click to expand...

That was exactly my reaction to getting it right - astonishing how much better it sounded than just a little off. Now you know why I was so insistent on getting the all pass section on the board.

Thanks for the update on your bypassing. I guess I'll have to try it without the tantalums just to see if the LM6172 is stable that way.
 
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