New face in op amp industry

[hetzer]

I was investigating Khadas tone board and I found out that they used RT6862D and RT6863D at amplifying stage. There is nothing about those chips on internet and even the distributers like Mouser and Digichip have no information about them.

Since those chips show superb performance as shown on tone board, I tried to figure out the manufacturer. Richtek names their chips starting with RT, but there was no RT6862,3 on Richtek website.

But I found out that there were some sellers in China and they sold it with ESS dac chipsets in common. Then I managed to find another product using ess dac and RT6863.
https://world.taobao.com/item/561343166831.htm
https://www.chinahao.com/product/561343166831/

According to my basic Chinese, this chip is able to produce over 100ma of constant current output, which is enough to drive headphones. And it is made by ESS.

As I don't trust Chinese sellers so much, it doesn't seem to be a reliable information. But as there is no other information about this chip and ESS is actually interested in amplifier(as they are expanding mobile audio solution lineup for smartphones), maybe ESS is making a series of op amp. Even though it isn't made by ESS, the presense of high current op amp with low noise and distortion is a good news for DAC developers.

It will be great if there is more information about RT6862D and RT6863D in this thread.

 

[Bamboszek]

Seems like they are made by company named Semiteh. Apart from jellybean parts like 072 or 5532 they offer some really interesting chips. Especially SRT6879 or SRT6863 looks very promising. Datasheets could be found there - http://www.semiteh.com/product.asp?ParentID=187&cid=187
I've sent them an email asking about samples or European distributor. I'm thinking about making DIY heapdhone ampifier with those opamps.

 

[GeekyBastard]

It's made by Semiteh (胜敏特), a mysterious Chinese company, not ESS, not much information for it online either.

Here's a datasheet.

 

[Bamboszek]

Still no answer from Semiteh. Looks like they are focused on Chinese market only. It's a bummer as it is really hard to find comparable devices from other manufacturers.

 

[Marvin]

This was posted on Khadas forum with a note that it's a Japanese manufacturer:

 

[Aldoszx]

Everything i've found about Ricore Thehnology is an old site:
http://ricoretech.com/about.asp
But it is Chinese one !

 

[IVX]

And actually, both opamps are the same junk

 

[Bamboszek]

Why junk? Datasheet doesn't looks bad, Khadas proves they can offer good performance and I guess they are considerably cheaper than offerings from TI for example.

 

[IVX]

right, it's about half the price of opa1612, maybe cheaper, after test those chips I didn't back to bargain, maybe possible to get 1/3-1/4 price.
I hate such ugly clipping behavior(any real opamp of serious manufacturers have an ideal clipping without screeching) and one that fact is enough to me to consider that chip junk. However, I remember that the chip was about 3 times worse vs opa1612 regarding noise in I/U stage and even more noisy than opa1602 which draws 3x times less current. So I've no interest to use it and do not support the hype-makeup around that cheap chip. Seems it possible to buy a big enough batch of SGM8261 with any ordered marking, like "bravissimo", "virtuoso", "maestro" or even "mussolini" and BS like that to use inside of overpriced DACs
Actually, the ignorant datasheet itself is enough for an experienced engineer to see that this is junk, SGM8261 pdf looks more professional that's why I believe SGM is the origin.

 

[Bamboszek]

Well, I skimmed thru SGM8261 datasheet before earlier post and seemingly it looked ok but somewhat familiar.
Now I double-checked and my doubts were right. SGM pdf is exact copy-paste from TI datasheet with changed numbers.
Just check page 13 of both datasheets:
1588065399.pdf (sg-micro.com)
SoundPLUS™ High-Performance, Bipolar-Input Audio Op Amp datasheet (Rev. B) (ti.com)
So you're right, there is something shady and those chips are better to be skipped.

 

[IVX]

Bamboszek, I tell you, they may call that "mussolini"

 

[FireLion]

Whats the practical application here? Is it available in commonly used packages?

 

[gvl]

Where can I source RT6863S? May need one or two for a Soncoz restoration project.

 

[Tortie]

SHANLING uses these garbage Chinese opamps in their pricy USB dongle, the UA5.

 

[IVX]

I have to say that this opamp has a very well input stage symmetry which is better than opa1612, opa2156, opa1656, ADA4898, and many-many other opamps 3-4x more expensive. This is a rarely needed parameter as I guess but some of the measurement tasks require that kind of symmetry, and I just bought 1K pcs of RT6863S to use that in the Cosmos APU, it wasn't an economic choice at all.

 

[Tortie]

I have to say that this opamp has a very well input stage symmetry which is better than opa1612, opa2156, opa1656, ADA4898, and many-many other opamps 3-4x more expensive. This is a rarely needed parameter as I guess but some of the measurement tasks require that kind of symmetry, and I just bought 1K pcs of RT6863S to use that in the Cosmos APU, it wasn't an economic choice at all.

So you've changed your opinion on these opamps? You're not bothered by the plagiarism of the Texas Instruments spec sheet or the mysterious origin of the manufacturer?

 

[IVX]

I did not change my opinion I do confirm an ugly clipping behavior of that opamp, and I'll never use that as an output stage for the headphones amp for that reason. Also, that opamp has a fragile-unprotected input stage and its manufacturer recommend adding zeners there to clamp input at 5V or so. Hence, I'll never use that as an input stage as well. The ugly clipping is the sign of a low phase-margin, and in fact, I wasn't able to get a stable work that opamp in the composite configuration. So, this opamp is only suitable in my particular device as a buffer after the notch-filter, I see no another role for that.

 

[Holmz]

The “new face” doesn’t look like a Bob Widar face, nor his mannerisms.

 

[Njoy]

I did not change my opinion I do confirm an ugly clipping behavior of that opamp, and I'll never use that as an output stage for the headphones amp for that reason. Also, that opamp has a fragile-unprotected input stage and its manufacturer recommend adding zeners there to clamp input at 5V or so. Hence, I'll never use that as an input stage as well. The ugly clipping is the sign of a low phase-margin, and in fact, I wasn't able to get a stable work that opamp in the composite configuration. So, this opamp is only suitable in my particular device as a buffer after the notch-filter, I see no another role for that.

I do own Khadas tone board and E1DA 9038D.I do prefer your dac,as I use it with headphone amplifier.My question is, fiio is using this op amp in Ka 3 usb dac.Why is this op amp a bad choice for headphone amplification ? None of the reviews ,both subjective and objective mention it is bad performing.

 

[IVX]

I do own Khadas tone board and E1DA 9038D.I do prefer your dac,as I use it with headphone amplifier.My question is, fiio is using this op amp in Ka 3 usb dac.Why is this op amp a bad choice for headphone amplification ? None of the reviews ,both subjective and objective mention it is bad performing.

as I said the ugly clipping is a bad idea to use that opamp in such a role where a clipping is very probable.