OPA1656: High-Performance CMOS Audio Op Amp - Page 41

HpW · 24th November 2020, 07:49 PM

Quote:

Originally Posted by syn08

OPA1656 is less noisy than the OPA827, 2.9nV/rtHz vs. 4nV/rtHz both flat.

See attached, Jan is using the opamp for his project MRK 3 input box (input attenuation & gain) prior an ADC for measurement purposes

Currently it is not clear, how the measurement (customer) setup was really done... balanced input & output of his upcoming gear

While did many noise simulation with LTSpice for a SVF notch (state variable filter) and the winner was always the OPA827 even in LTSpice FFT graphs.

Hp

syn08 · 11:12 PM

What should I look at? OPA1656 is clearly lower noise.

If you believe some simulation results over the datasheets that's your choice (and problem, I would say).

MarcelvdG · 24th November 2020, 11:02 PM

1652?

chris719 · 24th November 2020, 11:44 PM

Quote:

Originally Posted by syn08

What should I look at? OPA1656 is clearly lower noise.

If you believe some simulation results over the datasheets that's your choice (and problem, I would say).

It is, wideband, for sure. Maybe he's talking about 1/f or strictly in a 20 kHz bandwidth where it may be close due to the higher noise corner.

syn08 · 24th November 2020, 11:58 PM

Which is why I started the OP with:

Quote:

Originally Posted by syn08

Not sure if we have the same understanding of "noise figure"

chris719 · 6th December 2020, 10:09 PM

Apologies if this has been addressed by John in the thread already, but does anyone know if there are plans for a single version of this or OPA2156?

johnc124 · 6th December 2020, 10:24 PM

Yes, there are definitely plans, the team is just spread really thin at the moment. But stay tuned, the single and quad channel options are on the way.

Sam1964 · 01:15 PM

Quote:

Originally Posted by johnc124

The input stage on the OPA2156 is rail-to-rail, and uses slew boosting to improve the settling time (notice the higher slew rate). Slew boosting is something I don't think most customers are aware of, and we never really do it in audio power op amps.

PCM1704 datasheet

Quote:

Figure 5 shows single channel circuit connections for a typical PCM1704 application. It shows the PCM1704 interface to the digital filter, the I/V converter, and the DAC post filter. Selection of an appropriate op amp for the I/V converter is critical for obtaining optimum dynamic performance from the PCM1704. The OPA627 is recommended for this application. Op amps with similar characteristics and faster settling times may also be used.

ts Settling time

OPA627 0.01% 550 ns

OPA1656 0.01%, 800 ns
OPA2156 0.01%, 600 ns

Why it happens? Or is i / u not an audio?

HpW · 31st December 2020, 10:08 AM

Quote:

Originally Posted by syn08

What should I look at? OPA1656 is clearly lower noise.

If you believe some simulation results over the datasheets that's your choice (and problem, I would say).

After time, here to drawing's to compare:

. OPA1556 for audio

. OPA827 for instruments

while Jan's auto ranger is for measurement and sholul be ways better than the DUT.

IMHO, or 2 cents

Gonethesame · 11th January 2021, 03:35 PM

Hi, Would like to thanx Johnc124 for all the good advices , and all members to this thread.

just replaced my already very good opa2134 on my dac analog pre-output with the opa1656, and not only it keep warmness of the opa2134 but feeds more details to my Naim amp hifi system , which is amazing !

so one more time thx

G.

24th November 2020, 10:49 PM	#402
syn08 diyAudio Member Join Date: Aug 2005 Location: Toronto	What should I look at? OPA1656 is clearly lower noise. If you believe some simulation results over the datasheets that's your choice (and problem, I would say). Last edited by syn08; 24th November 2020 at 11:12 PM. Reason: Typo fixed.

6th December 2020, 10:24 PM	#407
johnc124 diyAudio Member Join Date: Jan 2006 Location: Tucson, AZ	Yes, there are definitely plans, the team is just spread really thin at the moment. But stay tuned, the single and quad channel options are on the way. __________________ General Manager - TI Linear Amplifiers Business Unit OPA1637: New Fully-Differential Amplifier for Audio

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24th November 2020, 11:02 PM	#403
MarcelvdG diyAudio Member Join Date: Mar 2003 Location: Haarlem, the Netherlands	1652?

6th December 2020, 10:09 PM	#406
chris719 diyAudio Member Join Date: Jun 2004 Location: Connecticut	Apologies if this has been addressed by John in the thread already, but does anyone know if there are plans for a single version of this or OPA2156?

11th January 2021, 03:35 PM	#410
Gonethesame diyAudio Member Join Date: Oct 2008 Location: France	Hi, Would like to thanx Johnc124 for all the good advices , and all members to this thread. just replaced my already very good opa2134 on my dac analog pre-output with the opa1656, and not only it keep warmness of the opa2134 but feeds more details to my Naim amp hifi system , which is amazing ! so one more time thx G.