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DIY Simple Active Preamp

HypnoToad said:
On a dual adapter with two LME49990's, one on top and one underneath, you would solder it across pins 4 & 8 on the adapter as they are the power input pins.

This may help, I haven't tried it, you would have to try it and see if the chips still get hot.

CapCompensation_zps36b7f165.jpg
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Did as I was told :D, soldered the cap between 4 and 8 on the adaptor, now runs 15-0-15 at the same temp as 49990's on the ad797. Seems like the higher voltage brings the mids forward a bit, sounding very neutral to my ears now. I'm having a tough time choosing between the 49990 and opa2134.

2134 sounds heavier, almost like lowering impedance on a mc cart, very solid, defined and controlled, detail and soundstage take a step back. 49990 sounds "quicker" soundstage and highs are more pronounced, midbass and sub are tight and fast but less punch.

Tough choice, I like both flavors!
 
Phantom said:
Did as I was told :D, soldered the cap between 4 and 8 on the adaptor, now runs 15-0-15 at the same temp as 49990's on the ad797. Seems like the higher voltage brings the mids forward a bit, sounding very neutral to my ears now. I'm having a tough time choosing between the 49990 and opa2134.

2134 sounds heavier, almost like lowering impedance on a mc cart, very solid, defined and controlled, detail and soundstage take a step back. 49990 sounds "quicker" soundstage and highs are more pronounced, midbass and sub are tight and fast but less punch.

Tough choice, I like both flavors!
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Well that's good to know that the cap cured the oscillation/overheating problem.
 
Finally got around to building the Simple Preamp. Quite impressive for so little parts.
Compared to my hotrodded DCB1 its quite similar, dont lose any details as far as i can hear. Its just a little "hot" for me. I'll do some opamp rolling.

Thank you Phillip for another great diy :)
 
vinylb said:
Finally got around to building the Simple Preamp. Quite impressive for so little parts.
Compared to my hotrodded DCB1 its quite similar, dont lose any details as far as i can hear. Its just a little "hot" for me. I'll do some opamp rolling.

Thank you Phillip for another great diy :)
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Sometimes less is more. :yes:
 
HypnoToad said:
Well that's good to know that the cap cured the oscillation/overheating problem.
Click to expand...

I'm going to build the SSP and run it with the OPS at about +/-10V.
As I understand it, there have been no problems of oscillation with the LME49990's at this voltage.
So the ceramic cap is only needed when feeding these OP-amps with higher voltage?
 
AnteEB said:
I'm going to build the SSP and run it with the OPS at about +/-10V.
As I understand it, there have been no problems of oscillation with the LME49990's at this voltage.
So the ceramic cap is only needed when feeding these OP-amps with higher voltage?
Click to expand...

I would leave the caps in place no matter the voltage in the SSP.
 
Is there some consensus on the tonal characteristics of the three chips and how their sound is influenced by the supply voltage (is. Recommended voltages for the various chips and results?)
 
Jay, one dog, and she helps eat lunch regularly.

Steve, Agreed, but it is going to Jay Nations, the guy who owns Raven Records here.
 
I have spent part of the afternoon pouring over this long, LOOOOONG thread.

Noticing that the circuit uses the non-inverting input. I have an SSP partially assembled. Has anyone used a jumper from the output to the inverting input? That is a standard 1:1 buffer circuit.
 
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Well, I'm finally home from what should have been a 3-4 hour visit. I was wrong, he doesn't need a preamp, he has one.

I should visit more often. Or maybe it is we get into the music and forget the equipment. Yeah, I'll go with the last one.
 
I have a question Grainger49. Other than wanting to impart tonal qualities, as in "I really like the sound of a 741" what would be the purpose of having a 1:1 buffer circuit in a signal path?
 
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