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Old 3rd December 2009, 08:15 AM   #11
massimo is offline massimo  Italy
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If somebody is thinking to design a suitable pcb (smd preferred) a good idea could be to provide a pcb connector for a daughter board that will host all the C & R that set the LP/HP filters in order to change frequency in a while.
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Old 3rd December 2009, 08:22 AM   #12
njepitt is offline njepitt  United Kingdom
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Jacques,

Thanks for the answers.

Quote:
Originally Posted by Tea-Bag View Post
Jaq.
I think this is a cool design, worthy of it's own thread.
I agree. Perhaps the moderators could split off the (still few) relevant posts in a new thread?

Cheers

Nigel
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Old 3rd December 2009, 09:05 AM   #13
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Quote:
Originally Posted by Jacques Merde View Post
Hello Nigel,

I do have a solution for the low pass bandstop response issue, which I will post later.

Thanks,
Waiting with baited breath I've almost finished sorting my 100 jfets into 0.5ma ranges, the timing of you posting this Jacques is very good indeed, I'm very happy I have dilly dallied around and not built a conventional B1 with PLXXO because *this* is what I really wanted Thank you for posting!!

Tony.
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Old 3rd December 2009, 11:24 AM   #14
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Default B1 Active Crossover

This has generated enough interest that I think it makes sense to start a separate thread, so here it is. If the moderators could move the relevant posts from the B1 Buffer Preamp thread to here it would be much appreciated.

A solution to the bandstop response issue in the low pass section is to provide a separate buffer for the feedback cap, blocking the forward signal path to the output. This increases the stopband attenuation to greater than 100 dB.

I've eliminated the trimpot from the LP section, as I don't need it in my particular application.

I've been busy with work, but I'll post more here as soon as I get an opportunity.

Cheers,
Attached Files
File Type: pdf LR2.pdf (8.0 KB, 967 views)
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Old 3rd December 2009, 11:57 AM   #15
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Your schematic have a serious error!

/RK
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Old 3rd December 2009, 12:15 PM   #16
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Quote:
Originally Posted by R-K Rønningstad View Post
Your schematic have a serious error!

/RK
Could you be more specific?
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Old 3rd December 2009, 12:28 PM   #17
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Sorry, was not reading your text
Seems you intentionally do not have a connection from the p section to the output buffer.
You say: "A solution to the bandstop response issue in the low pass section is to provide a separate buffer for the feedback cap, blocking the forward signal path to the output. This increases the stopband attenuation to greater than 100 dB"
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Old 3rd December 2009, 12:58 PM   #18
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Hi, I've only read the first few pages of the B1 thread, but am I right in assuming this is the B1 with a LR crossover? Good for people who want to bi-amp if so.

May I ask if it's 24db/oct or 12db/oct? Also, what is the crossover frequency?
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Old 3rd December 2009, 01:34 PM   #19
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Quote:
Originally Posted by MikeHunt79 View Post
Hi, I've only read the first few pages of the B1 thread, but am I right in assuming this is the B1 with a LR crossover? Good for people who want to bi-amp if so.

May I ask if it's 24db/oct or 12db/oct? Also, what is the crossover frequency?
The relevant posts over in the B1 Buffer Preamp thread are: 2012, 2017, 2019, 2021, 2026, 2027, 2028, 2029, 2030, 2031, 2032, 2033, 2034 & 2035.

This a 2 pole (12dB/oct) LR filter at 700 Hz. It should be fairly straightforward to implement 24dB/oct.
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Old 3rd December 2009, 05:26 PM   #20
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Quote:
Originally Posted by Jacques Merde View Post
If the moderators could move the relevant posts from the B1 Buffer Preamp thread to here it would be much appreciated...The relevant posts over in the B1 Buffer Preamp thread are: 2012, 2017, 2019, 2021, 2026, 2027, 2028, 2029, 2030, 2031, 2032, 2033, 2034 & 2035.
Done. Supplying the post numbers is greatly appreciated.

dave
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