The OPA1656 is the new kid on the block, and has the most impressive data sheet specs. HOWEVER......the OPA1642 draws about HALF the current, its gain bandwidth is about 1/5th, has nearly equal specs, and is about 25% less costly. The lower current draw, bandwidth, and cost make it perhaps the better choice for retrofitting into older circuits.
But what will be reliability with 48V supply voltage when datasheet quotes 40V as absolute maximum?
I just found the issue.
Removing TC=0,0 for all C components in the LIB file and the model work for Micro-Cap 12 as well.
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here's one from a battery powered low voltage design I've been working on with the OPA1656, -3dB at 741kHz
Fully Differential Headphone Amplifier
....this thread is about the OPA1656 Jan.
any insults to offer?
act more appropriate for an magazine author perhaps?
any insults to offer?
act more appropriate for an magazine author perhaps?
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Stupid question from newbie, have twelve OPA2134 in my amplifiers in dip8 container. Can I just swap it on OPA1656 with just a dip8-soicd switch? The system with active crossovers, so one channel of amp amplifiers some frequency range, each channel have 3 OPA2134, one for gain, and other 2 I dont know. I even thought to use for highs (6khz+) according to specs OPA2156 😀. I very like those amps (2 x 4 channels), but I dont like tube sound they provide, I have scanspeaks as drivers and dont need more "tube" warm sound.
So I have heard about replacement by OPA627, and OPA637, have some originals from ti . com, but I think they will be "tuby" too. So what I need to do to make them work or can you recommend opa1656 as replacement for OPA2134? Some photos:
Imgur: The magic of the Internet
Bottom one is NE5532, I guess for active filtering, not used because I use DSP and bypassing signals.
So I have heard about replacement by OPA627, and OPA637, have some originals from ti . com, but I think they will be "tuby" too. So what I need to do to make them work or can you recommend opa1656 as replacement for OPA2134? Some photos:
Imgur: The magic of the Internet
Bottom one is NE5532, I guess for active filtering, not used because I use DSP and bypassing signals.
First you must determine the minimum requirements for an op amp in your circuit, and then screen
the op amp parameters for candidate parts. The OPA627 and the OPA637 are not interchangeable
with one another in many circuits, for example.
https://www.ti.com/amplifier-circuit/op-amps/products.html
the op amp parameters for candidate parts. The OPA627 and the OPA637 are not interchangeable
with one another in many circuits, for example.
https://www.ti.com/amplifier-circuit/op-amps/products.html
Rayma, thank you, so I can just take OPA2134PA and replace by OPA1654, also as dual OPA627 because they have same circuits, but ofc I cant use OPA637 because it's require Gain >= 5, and there is maximum G=3 in those circuits
adapter boards and high speed...
Using adapter boards for fast opamps is usually asking for trouble. Are there any recommendations how to do it right (assuming you want to replace a DIP8 opamp with the OPA1656) ?
Where do you place the caps (which size) ?
Using adapter boards for fast opamps is usually asking for trouble. Are there any recommendations how to do it right (assuming you want to replace a DIP8 opamp with the OPA1656) ?
Where do you place the caps (which size) ?
I believe the main problem in using adpters is when you are plugging a fast DIP-8 opamp into a socket. So the contact between pins and sockets might be capacitive, particularly after some time.
Perhaps something to try is to "slightly solder" the input and output pins to the socket. Using just the minimum solder necessary to bypass the contact, but still allow removing it.
Just thinking.
Thank you, but in this case you have supply and GND on the small PCB. My problem is how to handle DIP 8.
My idea : don't use the socket, put the small PCB on the main PCB and make the connection by soldering the 8 individual pins (easy to desolder). But there is still the problem of the caps being quite far away.carlmart said:
Why is that? As long as you put a 100nF cap between the rails, there should be no problem.
The main possible problem is that an adapter increases parasitic capacitance between pins. In particular, any capacitance from the inverting input to other pins or ground can cause oscillations.
The good news is that in audio, impedance levels are relatively low so parasitics need to be larger to have a bad effect, and most audio opamps are not really high speed. I would not classify the OPA1656 as a high speed amp in this context. I routinely use OPA1656 and related on adapters without any issues.
The idea to put a supply decoupling SMD cap on the back side of the adapter is a good one.
Jan
The good news is that in audio, impedance levels are relatively low so parasitics need to be larger to have a bad effect, and most audio opamps are not really high speed. I would not classify the OPA1656 as a high speed amp in this context. I routinely use OPA1656 and related on adapters without any issues.
The idea to put a supply decoupling SMD cap on the back side of the adapter is a good one.
Jan
I guess 'should' is the keyword. It worked quite often, but not always for me. maybe multi-resonance from too many opamps, 100nFs and electrolytics combined.
OPA1656 rolling
I tried in all cases to bypass the rails with a 0.1F X7R on the backside with the shortest possible lead length. I had no oscillations or instability with the OPA1656. (or the 2156)
The opamp has good phase margin and seems quite tolerant of sub-optimal layout.
I used 10 or 12 in my preamp rolling project - never a problem with the 1656.
The preamp design however was another story - The Carver C-2 has tone control designed by a moron. The Doug Self inspired redesign works as it should.
I tried in all cases to bypass the rails with a 0.1F X7R on the backside with the shortest possible lead length. I had no oscillations or instability with the OPA1656. (or the 2156)
The opamp has good phase margin and seems quite tolerant of sub-optimal layout.
I used 10 or 12 in my preamp rolling project - never a problem with the 1656.
The preamp design however was another story - The Carver C-2 has tone control designed by a moron. The Doug Self inspired redesign works as it should.