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Old 25th October 2009, 03:28 PM   #1971
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oww yes i see now..i forgot the topologies but now i remembered..for single supply ,sinusoidal signal plus dc together goes into the jfet and output cap filters dc..yes i see.thank you
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Old 10th November 2009, 07:46 AM   #1972
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Question B1 in an active filter?

The B1 buffer is essentially a voltage follower.
A voltage follower is also an essential part of a Linkwitz-Riley filter.
See this: Active Filters

Has anyone tried the B1 voltage follower as a component in a Linkwitz-Riley filter?
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Old 10th November 2009, 02:20 PM   #1973
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Question B1-converted D/A-converters?

Lampizator is a CD-player or a DAC modification. The idea is to replace the active op-amp filters and buffers after the D/A-converter with a single-ended triode amplifier stage, thus avoiding numerous transistor stages of the op-amps.

I thought that basically the same could be done with a simple Class A JFET amplifier, possibly using a B1 stage. Because B1 is a voltage follower buffer, it could be developed to a Linkwitz-Riley low-pass filter, like I said in my previous post.

Read this too: How Lampizator CD tube player sound?
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Old 10th November 2009, 03:24 PM   #1974
DougL is offline DougL  United States
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Quote:
Originally Posted by Nikolas Ojala View Post
The B1 buffer is essentially a voltage follower.
A voltage follower is also an essential part of a Linkwitz-Riley filter.
See this: Active Filters

Has anyone tried the B1 voltage follower as a component in a Linkwitz-Riley filter?
This is a perfect application for a B1 type circuit. For LR4, you probably need 3 B1 circuits, one as input buffer and another for every L2 Butterworth stage.

HTH

Doug
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Old 10th November 2009, 05:23 PM   #1975
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Quote:
Originally Posted by Nikolas Ojala View Post
The B1 buffer is essentially a voltage follower.
A voltage follower is also an essential part of a Linkwitz-Riley filter.
See this: Active Filters

Has anyone tried the B1 voltage follower as a component in a Linkwitz-Riley filter?
I agree, it seems like an ideal application for B1. It is on my list of things to do "real soon now".
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Old 25th November 2009, 11:24 AM   #1976
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Quote:
Originally Posted by Jacques Merde View Post
I agree, it seems like an ideal application for B1. It is on my list of things to do "real soon now".
I don't really know what i'm doing, but in LTSpice I knocked up a pair of Salas's direct-coupled B1-type buffers in 24dB L/R high-pass, and apart from an enormous insertion loss, it performs as I expected. Oh, and with more than 0.015% THD+N @10kHz but I suspect that's due to the sim looking at everything up to 200kHz. I'd really like to build this to test it, as I'm keen on attempting to bi-amp my system. Should I start a thread on it? I haven't managed to find anything really complete on the 'net so far (so far~) about active crossovers without opamps.

Last edited by derwhalfisch; 25th November 2009 at 11:31 AM. Reason: numbers were wrong
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Old 25th November 2009, 12:32 PM   #1977
Floric is offline Floric  Europe
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Quote:
...a pair of Salas's direct-coupled B1-type buffers in 24dB L/R high-pass, and apart from an enormous insertion loss, it performs as I expected...
I don't see any reason for this insertion loss. And as far as I remember, there was none in my simulations. I think you did something wrong.

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Oh, and with more than 0.015% THD+N @10kHz but I suspect that's due to the sim looking at everything up to 200kHz.
You should not trust the THD+N simulations of spice too much. Just regard it as a tendency.

regards

Flo
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Old 25th November 2009, 12:40 PM   #1978
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@Floric:

I'm sure I did something wrong ;P
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Old 25th November 2009, 02:31 PM   #1979
AndrewT is offline AndrewT  Scotland
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in the passband of each part of the crossover there should be near zero insertion loss.
You either (virtually) wired it up wrong or you asked the simulator the wrong question.
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Old 25th November 2009, 02:44 PM   #1980
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Figured it out, crossover resistor values were too low compared to the input 'stopper'... less than 1dB loss now.
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