Ok calculate the output impedance of the opa1622 with a negative feedback of 1k
The negative feedback is sensing the output voltage. It is the open loop output impedance at given frequency and divided by the open loop gain of whatever the frequency your are looking at assuming +1 gain configuration. Typical output impedance is lower than 0.01ohm under 10khz..As the ballast resistor is outside the feedback loop it is directly added to the output impedance.
Just for fun I assembled a very simple HPA using an OPA1622 on a dip socket from Ebay https://www.ebay.com/sch/i.html?_fr...RC0.A0.H1.XOPA1622.TRS1&_nkw=OPA1622&_sacat=0 and used this module from Ebay Dual OP Amp Preamp DC Amplification Board PCB for NE5532 OPA2134 OPA2604 AD826 | eBay
I simply shorted the current limiting output resistor on the module and hooked it up. Remember to decouple the power on the board
With a LM317/337 it was not that great, midbass bloom, lack of transparency. Then I powered it from a improved Sulzer power supply and it came alive. This thing lets you hear everything attached to it and will easily reveal weak links. As someone mentioned, it needs a good power supply......not because it is weak but it will pass information very well. Not harsh at all, very balanced and extremely detailed without being sterile or harsh. I can see putting a Jung Didden super reg on this and make it my main HPA. The HPA without power supply is little more than 1 square inch. I will probably mount it directly on the RCA jacks...this minimizing wiring.
Have fun. Without power supply, about $10
I simply shorted the current limiting output resistor on the module and hooked it up. Remember to decouple the power on the board
With a LM317/337 it was not that great, midbass bloom, lack of transparency. Then I powered it from a improved Sulzer power supply and it came alive. This thing lets you hear everything attached to it and will easily reveal weak links. As someone mentioned, it needs a good power supply......not because it is weak but it will pass information very well. Not harsh at all, very balanced and extremely detailed without being sterile or harsh. I can see putting a Jung Didden super reg on this and make it my main HPA. The HPA without power supply is little more than 1 square inch. I will probably mount it directly on the RCA jacks...this minimizing wiring.
Have fun. Without power supply, about $10
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Just for fun I assembled a very simple HPA using an OPA1622 on a dip socket from Ebay https://www.ebay.com/sch/i.html?_fr...RC0.A0.H1.XOPA1622.TRS1&_nkw=OPA1622&_sacat=0 and used this module from Ebay Dual OP Amp Preamp DC Amplification Board PCB for NE5532 OPA2134 OPA2604 AD826 | eBay
I simply shorted the current limiting output resistor on the module and hooked it up. Remember to decouple the power on the board
With a LM317/337 it was not that great, midbass bloom, lack of transparency. Then I powered it from a improved Sulzer power supply and it came alive. This thing lets you hear everything attached to it and will easily reveal weak links. As someone mentioned, it needs a good power supply......not because it is weak but it will pass information very well. Not harsh at all, very balanced and extremely detailed without being sterile or harsh. I can see putting a Jung Didden super reg on this and make it my main HPA. The HPA without power supply is little more than 1 square inch. I will probably mount it directly on the RCA jacks...this minimizing wiring.
Have fun. Without power supply, about $10
The gain on that board is a bit too high. Short the 3k and disconnect the 1k. If you need gain, set it before the output stage. This way you can minimize the distortion and noise.
It was just to see what this tiny chip is capable of. Sure very surprising!
I will try suggestion though.
I will try suggestion though.
@Johnc124: I looked up the OPA1622's cousin, the INA1622, which I would be interested in. But none of the usual distributors seem to have it in stock. Is that released yet?
thanks, Jan
thanks, Jan
@Johnc124: I looked up the OPA1622's cousin, the INA1622, which I would be interested in. But none of the usual distributors seem to have it in stock. Is that released yet?
thanks, Jan
It's called ina1620 instead of 1622. As I just checked it's in stock on mouser digikey and ti online store.
Just for fun I assembled a very simple HPA using an OPA1622 on a dip socket from Ebay https://www.ebay.com/sch/i.html?_fr...RC0.A0.H1.XOPA1622.TRS1&_nkw=OPA1622&_sacat=0 and used this module from Ebay Dual OP Amp Preamp DC Amplification Board PCB for NE5532 OPA2134 OPA2604 AD826 | eBay
I simply shorted the current limiting output resistor on the module and hooked it up. Remember to decouple the power on the board
With a LM317/337 it was not that great, midbass bloom, lack of transparency. Then I powered it from a improved Sulzer power supply and it came alive. This thing lets you hear everything attached to it and will easily reveal weak links. As someone mentioned, it needs a good power supply......not because it is weak but it will pass information very well. Not harsh at all, very balanced and extremely detailed without being sterile or harsh. I can see putting a Jung Didden super reg on this and make it my main HPA. The HPA without power supply is little more than 1 square inch. I will probably mount it directly on the RCA jacks...this minimizing wiring.
Have fun. Without power supply, about $10
Thx it looks fun and very cheep.
Could I replace my Dantimax preamp module with lm317/337/PGA2310 with your suggestion plus a relay attenuator for maximum sound quality??
Best regards
IMO choosing audio opamps based on specs an sales blurr brings you nowhere.
Given my findings on the stellar spec'd INA1620 on their evaluation board being a variant of the OPA1622, I wonder if those guys at TI ever audition what they tout as "High-Fidelity Audio Operational Amplifier" or if those guys are close to deaf?
don't trash your TEAC UD-H01 DAC, pimp it!
don't trash your TEAC UD-H01 DAC, pimp it!
In short, the stock INA1620EVM board is crap in terms of sonic performance!!!
On top of that the PSRR and channel separation figures by no means reflect real world behaviour in the audio realm.
There is no other way than to try and audition by yourself.
Would love to pimp up my Teac P90 described here by swapping OPA or anything else, any ideas pls?
IMO choosing audio opamps based on specs an sales blurr brings you nowhere.
Given my findings on the stellar spec'd INA1620 on their evaluation board being a variant of the OPA1622, I wonder if those guys at TI ever audition what they tout as "High-Fidelity Audio Operational Amplifier" or if those guys are close to deaf?
don't trash your TEAC UD-H01 DAC, pimp it!
don't trash your TEAC UD-H01 DAC, pimp it!
In short, the stock INA1620EVM board is crap in terms of sonic performance!!!
On top of that the PSRR and channel separation figures by no means reflect real world behaviour in the audio realm.
There is no other way than to try and audition by yourself.
Did you measure anything or is this just your own unsubstantiated conjecture that the board design is bad and MLCCs are bad? Sounds like just your own personal opinion without any measurements.
Just starting to layout my headphone amplifier using the 4 x OPA1622, this project started from needing a headphone amplifier that could drive 4 x 32 ohm headphones from a digital source and needed or I wanted it to be battery powered ; my family enjoy watching movies together and headphones are our choice for listening and so this project came about.
The design will have individual volume control for each outlet and have 3 x sources of audio available, USB Audio Bridge, Optical SPDIF and stereo balanced analog inputs as well as balanced outputs all using mostly TI.com ICs. DIR9001 for digital interface, PCM1794A DAC, OPA1622, OPA1656 and OPA1637 for balanced output drive. Volume control can be selected for the XLR outputs or jumper out on the main PCB.
battery management is using TI.com BQ25616RTWR IC.
The design will have individual volume control for each outlet and have 3 x sources of audio available, USB Audio Bridge, Optical SPDIF and stereo balanced analog inputs as well as balanced outputs all using mostly TI.com ICs. DIR9001 for digital interface, PCM1794A DAC, OPA1622, OPA1656 and OPA1637 for balanced output drive. Volume control can be selected for the XLR outputs or jumper out on the main PCB.
battery management is using TI.com BQ25616RTWR IC.
So I realize this is an old thread but was not sure where else to put it. I bought an opa1622evm pcb and powered it with 2x 13v batteries. I then connected the balanced output of a topping e70 dac to it and with no load the evm measured 4.8 vrms in and at the output. So far so good. The chip wasn’t heating up, voltage was stable, and dc was a few millivolts at the output. I shut it down, and lowered the the output to -4db in REW generator and connected my cosmos adc to it in mono mode at 4.5v input( 800 ohms input impedance). I turned the board back on then the dac and poof. Magic smoke. Dac and cosmos are fine. Looks like the opa1622 blew. I don’t see what adding the 800 ohm load would have done to cause this. On the output of the evm which is SE, I connected only pin 2 and 3 or the xlr cable going into the balanced input of the cosmos adc( ground or pin 1 was not connected). The cosmos adc and the dac were connected to my laptop which was operating on battery. The dac was also connected to 110v. Does anyone have any ideas? Thx for any thoughts.
The usual way to go from bal <-> unbal: unbal ground to both bal ground and neg + unbal + to bal +. I'm not sure if this has any meaning to your unfortunate situation.
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I was aware but usually try it that way and ungrounded to check for least noise. The input to the cosmos is fully differential so I don't see how why I shouldn't have been able to do that.
Hello John, I have encountered a problem and need your help. There may be something wrong with the opa1622 official simulation model.
please check https://www.diyaudio.com/community/...-inductance-causes-gain-margin-issues.406194/
Because I don't have a corporate email, I can't report problems to the E2E forum.😢😢
please check https://www.diyaudio.com/community/...-inductance-causes-gain-margin-issues.406194/
Because I don't have a corporate email, I can't report problems to the E2E forum.😢😢
I built a unity gain circuit in TINA TI according to the datasheet and connected a 1nf load, and found that the phase margin did not match the official one.
The ina1620 is based on the opa1622, which adds 4 precision resistors and a signal input EMI filter, while the opa1622 is a simple amplifier.Is it better to use INA1620EVM or OPA1622EVM as headphone amp?
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