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Active filter board GB

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#1,121
Another GB?

I've had several requests for another round of Active Filter 4 boards. With enough interest I would offer AF4 boards (schematic attached) and PSU2.2 boards/parts kits. For newcomers, the PSU is a pair of discrete series regulators on a single 80x 100mm board, either fixed or adjustable voltage. I haven't compared it to a shunt reg, but to me it sounds better than chip based regulators.

I haven't priced it out yet, but suspect that pricing would be $5-6 a board at 100 pieces or more.

Please express interest here.
 

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#1,126
My advice is to not offer the PSU2.2 PCBs.
Leave it to the builder to choose between cheap and easy 317 regulators, or upgraded IC regulators, or discrete series regulators or IC/discrete regulators or any of a variety of Shunt Regulators.
The Salas Shunt is good enough for any IC crossover and is also good enough for the FET buffer crossover.
 
#1,127
Andrew, I understand your sentiment given your experience with the PSU2.2. Of course everyone is free to use their power of choice and I would offer the PSU 2.2 as a separate item if there is enough interest. These days it seems shunt power supplies are more fashionable.

For those who haven't followed this discussion, In its original configuration there can be startup issues with the PSU into low impedance loads (like 4 AF boards using Panasonic FC caps) This is due to Jens providing a low impedance path from the output to the voltage reference to make the reference quieter. Increasing that resistor's value from 1K improved startup performance while still providing a quiet feed for the reference.

Omitting the quiet power resistor completely works fine for me, with no noticeable difference in sonics in my crossovers/ systems. The voltage reference then sees the raw rectified voltage filtered by a CRC consisting of 3,000 uF 10K 1 uf. This does not provide enough current for the 9.1V zener option, but with an LM4040-10 and BC546C/BC556C differentials there is plenty of standing current.
 
#1,129
You undoubtedly have better test equipment than I do, but I do not recall anyone else reporting oscillation issues. I do recall that you have disagreed with some of Jens' layout choices on other projects that work just fine. IMHO layout optimization beyond meeting the stated goals becomes an art form. Artists are unlikely to agree on the "best" solutions. The same can be said for when to stop engineering. One self imposed constraint was that Jens wanted the board to fit in the footprint allowed in EAGLE's free version.

I like the way the PSU works in my crossovers, even if there is some low level oscillation. There are about 500 other boards out there. The lack of complaints other than yours would indicate that it sounds at least OK. for a while it was the hot upgrade on the Linkwitz Orion forum.

I don't want to get into a drawn out battle over the PSU merits or lack thereof. It will be available if there is enough interest, if not it won't bother me.
 
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