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Old 27th November 2009, 01:52 PM   #521
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Originally Posted by scott wurcer View Post
The LT1115 and LT1028 are the same chip BTW. I have been trying to sort out some paint hues from China the numbers have not helped.
The same chip that sounds different.. (the LT1028 definitely a better chip, for my ears)

Last edited by Andrea:; 27th November 2009 at 02:01 PM.
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Old 27th November 2009, 01:57 PM   #522
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Originally Posted by leeperry View Post
Andrea, please!! they're not ready for the whole op-amps numerology/colors, just yet

what does LT1124ACN8 say btw? coz I'll prolly get it soldered together w/ the burson anytime soon.
Hmm, not the most interesting of numbers... the most "musical" sounding of them being the 3 and the 5, for my ears. At any rate, there's also the sum of the numbers to consider - it'll give the overall "nature" of the opamp (or other). For instance...

The LT1028 = 11, which is a key number in numerology; meaning sort of the "reunion of the opposites". No wonder it's that good?

Also, take the LME49723 = 7 [you sum until you get a prime number], which is another very meaningful number... no wonder this one sounds better than the LM4562 and the rest?

And, LT1124 = 8, that is something like "fame & good fortune" but not perfection...

and LT1115 = 8 as well


Note that I'm not an expert in numerology by any means... but I've consistently found proof of what I'm saying (like it or not, you scientific minds).


Ah, and strangely I'm not surprised that the LT1115 is better known and/or more considered on audio forums than the LT1028

Last edited by Andrea:; 27th November 2009 at 02:13 PM.
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Old 27th November 2009, 02:20 PM   #523
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BTW, this thread has turned way bigger than I ever expected it would.
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Old 27th November 2009, 03:41 PM   #524
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BTW, burson told me "There are two LM7809 and LM7909 on the Prodigy HD2 soundcard, you can upgrade them to LM7812 & 7912. You may worry the drop off voltage of the power supply but from my own experiment it has been prevent to be very effective and our opamp couple perform even better with this mod."

but I've spoken to the EE who will solder them for me, and he's said that these parts need +4V headroom to regulate...so 12V in>12V out is not the best theoritical idea in his opinion, better get regulated 8.8V than unregulated 12V from the PC PSU(I've carefully chosen a PSU w/ the lowest ripple ever, though)

and he said that I need 0.1uf caps w/ the lowest value(the 630V Mundorfs MKP cap the original owner put is WAY overkill): http://www.bursonaudio.com/opamp101.htm
Quote:
Please solder a good quality foil capacitor (MKP caps) across the power intake pins (V+ and V-).
how about the best mundorfs money can buy w/ a low voltage

Last edited by leeperry; 27th November 2009 at 03:51 PM.
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Old 27th November 2009, 03:50 PM   #525
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If a regulator "drops out" it's not the dip in voltage that's an issue but the fact it then lets noise and ripple through

I'd love to give you guys some LM741's marked up as LT xxxx or something
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Old 27th November 2009, 03:57 PM   #526
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ok, so should I follow burson's advice or the EE's then?

I need 0.1uf, this one is max 630V and dimensions are 10*19: http://www.mundorf.com/english/baute...-mkprechts.htm

this one is 250V and 9*23: http://www.mundorf.com/english/baute...p-znrechts.htm

I'm not sure which one is better, I think the black one is higher grade?

Last edited by leeperry; 27th November 2009 at 04:13 PM.
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Old 27th November 2009, 04:14 PM   #527
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Fairchild quote 2 volts as the headroom required but that has to include ripple and spike etc. In other words if the input goes to 13.9 you may be in trouble. That 2 volts is the same for pos and neg regs and at the quoted current (1 amp)

Just measure it and see what you have to play with.
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Old 27th November 2009, 04:20 PM   #528
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well, it feeds 12.3V from the PC PSU and the op-amps get ±8.8V

oops, the black Mundorf are not MKP, they are KP...so my only option is the white MKP 0.1uf 630V basically? anyway, it sounds amazing so I can easily settle to it
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Old 27th November 2009, 04:22 PM   #529
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Surface mount caps are better as there is no lead inductance that negates their effectiveness at high frequencies. Mount them between the legs of the reg on the pcb. And being smaller they are less prone to pick up radiated noise etc....

You do know with non polarised caps of foil construction there is a "right" way round to connect them to take advantage of the outer layer of foil for shielding. Connect the outer to the lowest impedance or ground end
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Old 27th November 2009, 04:24 PM   #530
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12.3 is no good. You can raise the output of any 78/79 reg by adding a zener into the ground lead to lift the output. So a 7805 and 6 volt zener makes an 11 volt reg. There are better ways still using a small transistor and two resistor to "lift" the ground pin of the reg but the zener approach is fine.
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