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Old 29th December 2011, 04:47 PM   #381
gvelim is offline gvelim  United Kingdom
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Quote:
Originally Posted by MatchASM View Post
2. The relay RL6:B goes to L-OUT, whereas I think it should go to R+OUT. Is this a mistake in the diagram or a design (=manufacturing) error? Could someone check? I'm not upening up my dacmagic for the next couple of days...
Confirmed as a schematic error. On the PCB RL6:B goes to R+OUT.
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Old 29th December 2011, 04:52 PM   #382
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If you want to do a reform changing only the OPAMP, I recommend to you to replace them for OPA1612. It saw attentivly your photo and specifically the placement of the OPAMPS. I advise you to use less tin because it has too much and can generate oscillations or problems of noise and inclusive of contact.
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Old 29th December 2011, 09:31 PM   #383
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OPA1612 will not get any noticeable improvement to the already existing LME49720... At that level of performance there are practicaly identic to human ear.

Last edited by SoNic_real_one; 29th December 2011 at 09:34 PM.
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Old 29th December 2011, 09:36 PM   #384
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Quote:
Originally Posted by SoNic_real_one View Post
OPA1612 will not get any noticeable improvement to the already existing LME49720... At that level of performance there are practicaly identic to human ear.
ok.
Any other suggestions?

Or is it the generel design that is flawed?
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Old 29th December 2011, 10:41 PM   #385
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No, the high-performance OpAmps run usually hotter (lower the distortions). But if they are burning your finger they might auto oscillate - clean the solder points with isopropyl alcohol, check the decoupling caps (they need to be 2xSMD, close of OpAmp power terminals).
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Old 30th December 2011, 11:15 AM   #386
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Quote:
Originally Posted by SoNic_real_one View Post
No, the high-performance OpAmps run usually hotter (lower the distortions). But if they are burning your finger they might auto oscillate - clean the solder points with isopropyl alcohol, check the decoupling caps (they need to be 2xSMD, close of OpAmp power terminals).
I am also thinking of putting some aloycoolers on the opamp.

But what do you mean by "2xSMD"? Is it because there are 2 smd's - or?
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Old 1st January 2012, 08:39 PM   #387
gvelim is offline gvelim  United Kingdom
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"2xSMD" are the bypass capacitors already in place.


On another note, the decision to opamp selection should be based on the operational compatibility to the differential filter output stage (XLR out).

Hence I would be interested to understand what are the key spec requirements that we should be looking to match. Recommendations are most welcomed.



Also, by looking at the attached output impedances which one would be best suited for the XLR out stage ? shouldn't those different response curves be audible ?
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Old 3rd January 2012, 11:46 AM   #388
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Found these:

::: Zalman, leading the world of Quiet Computing Solutions :::

Maybe they could give sufficient cooling for Op-amps like LME4986 and LME4972, or at least keep them stable.
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Old 4th January 2012, 05:28 AM   #389
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do you guys think it will give any improvement if the opamp (ne5532) decoupling caps are increased to 0.1uF?

i think 0.01uF is a little low.. even cmoy decoupling caps are normally 0.1uF

Last edited by idjoel2000; 4th January 2012 at 05:34 AM.
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Old 4th January 2012, 10:35 PM   #390
gvelim is offline gvelim  United Kingdom
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Default Choosing and Using Bypass Capacitor

This might be of interest re: "Choosing and Using Bypass Capacitors"
http://www.intersil.com/data/an/an1325.pdf
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