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Old 12th March 2010, 01:03 AM   #1111
Salas is online now Salas  Greece
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The DCB1 is recommended and implemented with an opening relay, not a shorting to ground one. Now if someone has a need to temporarily short its output while fully driven etc. might risk the circa 6ma if forward biased by the signal, or up the buffering resistors value to the detriment of its subjective dynamics. Could use a further 220R on the grounding switch though and minimize risks by letting a little more signal through the next stage as most ground mute switches on gear do, leaving some little monitoring.
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Old 12th March 2010, 01:29 AM   #1112
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Default shorted DCB1...

or in order to retain the sonics (will lose a few db on max level), put a 1K0 (1000 ohms) in series with the input of the pot (CW terminal) so that even if the volume control is maxxed, Gate current can be limited to safe value.
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Old 12th March 2010, 02:45 AM   #1113
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The key assumption you're making is that muting/shorting occurs while at full signal. That's NOT what I expect. This will happen when there's little or no signal present. Then I think it'll be very safe to do.

My reasoning for this is to eliminate a relay contact point that's normally in the signal path ALL the time. (I realize it's not feasible with the board traces as they are now). This way, the relay is normally shorting to gnd for a few seconds during power-up, then is out of the signal path during normal listening.

Last edited by windowman99; 12th March 2010 at 02:49 AM.
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Old 12th March 2010, 05:24 AM   #1114
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Question looking for DCB1 schematic

Salas,
can you please point me to the schematic for the DCB1? i thought it was posted somewhere on this thread but i can find it. i'm curious as to why the DCB1 needs output spike protection at power on-- is it something to do with the regulator turn-on characteristics as the rail voltage rises?

thanks,
tincanear
aka Bruce W.
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Old 12th March 2010, 08:51 AM   #1115
Ian444 is offline Ian444  Australia
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Page 1 and 2 for schems, 1st post is good for relays. I don't know where "spike protection" came from, I believe the relay's purpose is to avoid DC on the output during power down. If one wanted to get rid of the relay, just turn off the DC B1 last, simple.

Ian.
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Old 12th March 2010, 07:18 PM   #1116
billyk is offline billyk  United States
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Quote:
Originally Posted by Ian444 View Post
Page 1 and 2 for schems, 1st post is good for relays. I don't know where "spike protection" came from, I believe the relay's purpose is to avoid DC on the output during power down. If one wanted to get rid of the relay, just turn off the DC B1 last, simple.

Ian.
AFAIK, it (the relay) was added for protection from DC
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Old 12th March 2010, 07:25 PM   #1117
Salas is online now Salas  Greece
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Ian described the main reason right. Beyond avoiding common pops on power up, the DC coupled circuit runs a short cycle of raised offset as its PSUs discharge not tracking each other exactly. So a little time to settle on power up and a fast release on power down is just what the doctor have ordered.
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Old 13th March 2010, 02:38 AM   #1118
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Thumbs up udailey fets

uriah,

thanks for the fets. got them today but i'm a bit confused about the markings. set of 4 with 5.94 5.96 are IDSS matched quad, but what about the 2 by themselves (one looks like 43190)?

-tincanear (bruce w)
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Old 13th March 2010, 02:49 AM   #1119
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Question question about salas' shunt reg pos

salas,

from the post (page 1 or 2) for the plusreg, it looks like Q6 is connected "backwards"-- i'm assuming that the fets are physically designed assymetrically (that behavior is different when S & D leads are swapped). For N-ch FET, wouldn't one want to connect the S and G together instead of G & D to make current source and also ensure that D is more positive relative to S&G ? or was it intentionally wired this way?

-tincanear
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Old 13th March 2010, 03:03 AM   #1120
Salas is online now Salas  Greece
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Its intentional. Creates different currents through the +/- shunts Leds, hence a little different voltages and manipulates the distortion profile in the way I liked it in 2008, since any kind of B1 will distort progressively as it ups level anyway. Some guy saw the manipulation opportunity again and asked here not a long time ago. Building a symmetrical psu B1 buffer. It can be put orthodoxically if middle leg is bend and soldered to S off board. Some did it and told me that they put it back. I give the orthodox way to those who use Hypno as a general shunt reg in the respective guide.
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