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Old 22nd August 2005, 12:59 AM   #1
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Default Which OPAMP

Which OPAMP would be best for the ESP P09 Xover? I was thinking about using an NE5532.. but I'm not sure which one of the NE5532s DIGI-Key lists I should use. Should I use on their NE5532s or would something else be better?



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Old 22nd August 2005, 07:03 AM   #2
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I'd use an OP275 instead of a NE5532, it's better sounding (sweeter) and has no dc offset to contend with 1to5mv, so can be direct coupled, unlike the NE5532 which i've seen sometimes at 400mv, and the OP275 can be cheaper, sometimes.
Or if you want what I consider to be the ants pants the AD825 but it's single and smd you have to get a dual Browndog adatper board and put 2 on it if you want 8 pin dil normal size, and they are tripple the price, but very very good, and still virtualy zero dc offset.

Cheers George
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Old 22nd August 2005, 11:08 AM   #3
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DC off-set is determined by circuit design. Ignoring input bias currents causes it.

Use an FET input opamp.

In order of price:
OPA2134(low price)
OPA2604(mid priced, good sonics, can run on 24V)
AD823 (most neutral, most expensive)
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Old 22nd August 2005, 12:37 PM   #4
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The OPA2134 (dual) is extremely good value and a great sound. I'll get shot down, but I preferred it to the OPA627 (single) which didn't do it for me at all even with taking care of the layout and having PS caps right at the power inputs.
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Old 22nd August 2005, 12:54 PM   #5
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OP275 and AD825 are both fet input

Cheers George
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Old 22nd August 2005, 02:10 PM   #6
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"OP275 and AD825 are both fet input"

The AD 825 won't fit the board layout

http://www.analog.com/en/prod/0,,759_786_AD825,00.html

and the OP 275 is not an FET input opamp

http://www.analog.com/UploadedFiles/..._c.pdf#search='OP275'

The FETs follow the BJT inputs, it has much higher bias currents (10,000X)) than an FET input design (.1A vs 10pA).
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Old 22nd August 2005, 09:30 PM   #7
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>The AD 825 won't fit the board layout<
Hence the dual Browndog boards.


>and the OP 275 is not an FET input opamp<
Read, It has Jfet's as it's input.

kestrel200 both these opamps have 1 to 3 mv dc offset



Cheers George
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Old 22nd August 2005, 10:09 PM   #8
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Thanks everyone! I think I'll try the 2134. But I have a new topic to debate. Do you think that the OPA2604 or the AD825 would be better to use in the ESP P88 PREAMP than the OPA2134s?

Mike
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Old 22nd August 2005, 10:52 PM   #9
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I heard the opa2604, it is good, but i think the OP275 sounds better, but from what i've listened to nothing so far can match the transient attack of the AD825. And it still stays smooth, if the rest of the system has no edge. It gives out whats put in.

Cheers George
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Old 23rd August 2005, 02:12 AM   #10
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"The maximum input differential voltage that can be applied to the OP275 is determined by a pair of internal Zener diodes connected across its inputs. They limit the maximum differential input voltage to 7.5 V. This is to prevent emitter-base junction breakdown from occurring in the input stage of the OP275 when very large differential voltages are applied. However, to preserve the OP275s low input noise voltage,"
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