I have one left ... PM me!
Just curious: did you use old vintage OPA827 or newer vintage? A TI engineer has posted on this board that a mask change was made to the OPA827 that improved it's performance. The later ones are measureably better than the earlier ones.I built my Opanamp1 using Craigtone's board. I used the ADA4627-1 for the gain stage and have had hundreds of hours of listening happiness. I used an LME49600 for the buffer (swapped pins around and deleted the bandwidth resistor) because I like it and had some on hand. I did not install the input diodes.
I tried the OPA 827 but it did not sound right. I since bought a couple OPA 828s but right now I just want to leave the Openamp1 like it is.
Some day when I feel more affluent, I might buy a couple OPA 627s to try.
The OPA 827s were purchased approximately December 2020 from Mouser. I have since gone to the OPA 1656 with the adapter wired for single channel, and like it a little more than the ADA-4627-1. For my MC cartridge, I put OPA-1656's in my Emerald in the second stage (AD797 input stage) with great success as well.Just curious: did you use old vintage OPA827 or newer vintage? A TI engineer has posted on this board that a mask change was made to the OPA827 that improved it's performance. The later ones are measureably better than the earlier ones.
mlloyd1
What is earlier and later?Just curious: did you use old vintage OPA827 or newer vintage? A TI engineer has posted on this board that a mask change was made to the OPA827 that improved it's performance. The later ones are measureably better than the earlier ones.
mlloyd1
I don't remember. Best to find johnc124 post on the topics. i'll search too but not right now ...What is earlier and later?
I used this technique professionally in a tape head preamplifier. Like a Phono cart, a tape head is primarily inductive and very low noise by itself. And like a phono cart, a tape head needs a damping resistor to control the resonance that occurs due to the amplifier's input capacitance. This technique works very well and I recommend it.Just finished building Opanamp1 using pcb from craigtone. Using Jung/Didden Superreg for the PS. Will listen for a few days and post my findings.
Question:
In reference to post#60
"above 1kHz the noise in MM preamp is dominated by the 47k standardized load resistor"
The following phono preamp uses what they call "electronic termination" or "“Electronic Cooling” and according to this whitepaper it reduces the input noise by (in the limit) 13.28 dB
whitepaper:
www.akitika.com/documents/ElectronicCooling.pdf
schematic:
www.akitika.com/documents/SchematicPhonoPreampRevB4.pdf
Does this technique reduce the noise caused by the loading resistor? Has anyone tried this?