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Old 17th November 2005, 03:22 PM   #211
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Added another option for PCB + Preprogrammed PIC at $15.
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Old 17th November 2005, 10:01 PM   #212
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What was the reason for switching to the BB opamp?
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Old 17th November 2005, 10:03 PM   #213
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It sounds just as good in this application, and I can include both input and output buffers for about the same price. We had been thinking about an optional input buffer, which would be fine, but a logistical nightmare to kit.
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Old 17th November 2005, 10:04 PM   #214
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Quote:
Originally posted by Evilsizer
What was the reason for switching to the BB opamp?

The main reason was to keep the kits affordable, as the AD8620 are about three times the price. The OPA2227 is a very solid audio opamp, and is used in a lot of great gear. It provides more than enough bandwidth, and sounds excellent. So it is a solid choice. Certainly one could order samples of the AD8620 and use them instead if you like.

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Old 17th November 2005, 10:17 PM   #215
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Quote:
Originally posted by Russ White



The main reason was to keep the kits affordable, as the AD8620 are about three times the price. The OPA2227 is a very solid audio opamp, and is used in a lot of great gear. It provides more than enough bandwidth, and sounds excellent. So it is a solid choice. Certainly one could order samples of the AD8620 and use them instead if you like.

Cheers!
Russ
THe ad8620 is a drop in replacement if one choses to use it?
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Old 17th November 2005, 10:20 PM   #216
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Yup. You can get a pair as samples from AD.
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Old 17th November 2005, 10:21 PM   #217
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Quote:
Originally posted by Evilsizer


THe ad8620 is a drop in replacement if one choses to use it?

Yes, just about any unity gain stable dual opamp with standard SOIC pinout will work just fine.
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Old 17th November 2005, 11:02 PM   #218
Lamicz is offline Lamicz  Czech Republic
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Hi Russ! I am definitelly noob, but I dont know what is this project about... It is preamp with digital SPDIF input or what? Cause i am going to build some good digital SPDIF preamp... Sry for OT
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Old 17th November 2005, 11:12 PM   #219
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This is a preamp that uses a digitally controlled Burr Brown volume control.

There is no pot in the signal path, which is a very good thing, the pot in the circuit sends variable voltage to an ADC on a microcontroller which in turn adjusts the volume on the PGA2311.

There is an input buffer to help high output impedance input sources, and an output buffer to help low impedance output devices like headphones and inverting gainclones.

The audio signal is always analog, and never converted to digital in any way.

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Russ
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Old 18th November 2005, 01:14 AM   #220
doggy is offline doggy  Canada
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Default opamp sockets

Just a question; is it possible to use an opamp socket on the board so that you could easily use different flavours of opamps like; opa2228, lt1361,opa2134,ne5532an,etc.

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