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pma

pma

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I have ordered from a certified TI distributor, Mouser, from Tx USA. I would never order a thing like this from AliExpress, CN.

I needed a balanced to SE converter for one of my soundcards, with lowest possible noise and distortion. I have put the EVM board into a shielded box

OPA1622EVM_box.JPG



Tis is the response to 10kHz square
OPA1622EVM_square.png


And this is the output noise with @22kHz bandwidth
OPA1622EVM_noise.png
 

SIY

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I have ordered from a certified TI distributor, Mouser, from Tx USA. I would never order a thing like this from AliExpress, CN.

I needed a balanced to SE converter for one of my soundcards, with lowest possible noise and distortion. I have put the EVM board into a shielded box

View attachment 182265


Tis is the response to 10kHz square
View attachment 182266

And this is the output noise with @22kHz bandwidth
View attachment 182267
I've been using their 1637 board for SE->BAL and BAL->SE. Superb performance.
 

MakeMineVinyl

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I'm currently building a PC for my wife.

PXL_20220127_163434097.jpg
 

Doodski

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Did a major upgrade of my gaming PC. This one is going to last several years+ or more before upgrading. New ASUS motherboard, DDR5, SSD NVMe M.2, 1000W power supply and a RTX3070Ti. Had to do some creative water cooling fan mounting to clear the motherboard heatsinks but it all fit with a proper layout to prevent air from getting into the pump. After I use it for a couple of weeks I'll overclock it although right now it is maxing out my A-level games at 165FPS+ so maybe no need to overclock just yet. Weird is that to get the boot drive to show in the BIOS I had to install the graphics card and could not use the onboard graphics. It took me 3 hours to figure that out but it's done now.
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Ricardus

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4 channel mid 70's API mic preamp clone.
 

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OP
pma

pma

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I think it's just the angle of the light.
Exactly.
Very cool stuff... is there a place where one can read about it?
I may consider opening a thread. It is a low power class A amplifier built 6 years ago, with some small modifications. It has been running several years in a daily operation.
The problem is that the distortion is so low that I cannot measure it reliably. The result is a mix of measuring system and amplifier limits :facepalm:. It is of course possible to make frequency response measurements and standard oscilloscope measurements without any restrictions. But the distortion measurements are system limited. AP2712 said H3 -129dB as a highest distortion component, 6 years ago, with a notch-filter method.
Due to non-switching output stage with local NFB, even the 15kHz @45kHzBW distortion is excellent.

classA_thd1k_6R8.png


classA_thd10k_6R8.png


Please forget the "+N" numbers, they are the system related noise.
 
Last edited:

Hipocrates

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I may consider opening a thread. It is a low power class A amplifier built 6 years ago, with some small modifications. It has been running several years in a daily operation.
That would be awesome, a great reading for sure.
It looks fantastic.
Thanks!
 
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pma

pma

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That would be awesome, a great reading for sure.
It looks fantastic.
Thanks!
Thread created :

 

novice

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I am curious what what is on your workbench right now.

Right now mine is elbow deep in tools and suffers from Any Horizontal Area Is Storage Fair Game syndrome. Discovered a flaw in my original workshop layout and blown away I missed something so obvious. Requires a major reorg which started yesterday as well as ritual self-flagellation.
 
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pma

pma

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My new MOSFET amplifier with error correction

PM-AB2_1stsample_bench.JPG
 

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restorer-john

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Audio Research D-70mkII. In for a little bit of work for a good friend. New Amphenol RCAs, a general clean/dust and full setup bias for a new set of tubes.

IMG_0286.jpg


What a gorgeous amplifier!

IMG_0290.jpg

250W consumption at idle at 65mA bias. Rock solid stability. Cover on or off. Set up 4 sets of dedicated monitoring cables and 4 DMMs. Each set of jumpers soldered to the points under the PCB and routed out to the DMMs. No other way unless you want to take a 300V+ hit. Can't do common earth with this puppy- has to be isolated.

IMG_0291.jpg


Love the ARC aesthetic and ethos.

IMG_0300.jpg


65mA target over all four OPT tubes.

IMG_0301.jpg
 
Last edited:

egellings

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Connect all 4 meters to a single voltage source of a size similar to what you are measuring in the amplifier and be sure they read the same. They not all be in cal, and you could have four slightly different bias settings.
 
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