Yes the LT1115 is a relaxed-specification (i.e. down-binned) new datasheet for the LT1028. If you had a blistering genius of a marketing guy, he could figure out how to sell it as an "Audio" opamp, at the same price as an LT1028. Scrape the bottom of the barrel and sell the slime as "pickle concentrate" -- genius.
I'm still failing to see why low drop out is a requirement. If you want the best power supply source for the application you specify that and define the starting rail(s) to support it surely?
Missing the point. If someone measures something and posts the measurements that is data that can be analysed. If someone says 'I heard a difference' it's just a story. Lots of stories might indicate something to investigate but isn't on it's own usable data. I never said anything about personal verification. You clearly are happy to believe JC has a magic coaster that makes his drinks taste better cos he said so. I'm not.
Some manufacturers do actually listen to their parts. Some even do mask sets of multiple parts during development.
That reading thing again Scott, I wrote it was not developed as an audio part. Marketing expanded the sales by selling some parts into a different marker at a lower price. I suspect that when demand requires it not all the parts shipped have relaxed performance.
Bill is the one with the funny hand!
Spec sheets usually don't show or even discuss the layout or process tweaks. To say that it is the same part with a different number is quite a stretch.
There can easily be similar max and min specs with totally different typical results. Do you have any die images to share?
Not a requirement for analog audio use, not for me anyway.
Those just happen to be the regulators that tout super low noise numbers, and measurement guys have been going gaga over them for quite some time.
Of course, there are some that could be used as regulators for opamp rails. LT3045 can output 15v, for example. Again, not a requirement for me.
The low noise is good for dac clocks and things of that nature. Some digital rails do very well with low noise LDOs. Just not AVCC.
Yes we all did when they don't work. You are making a connection which is the basic logical fallacy.
The LT1115 was not developed at all it is the LT1028. In fact I don't understand the whole story, generally any part that has fallout above 5% or so is flawed. 98% or so of functional parts meeting all specs was expected with laser trimming.
BTW if you talk process tweaks you are into millions and man years of work and qualification. Just think the "sound" of our resistors with a new thin film target, this is just fantasy.
Last edited:
As the person who actually developed many of those audio parts listed in a previous post, I thought I'd chime in. When I was defining TI's audio products I released:
OPA1688, OPA1622, INA1650/1, INA1620, OPA1678/9, OPA1692, and had started the OPA1671, OPA1656 and OPA1637 before moving to lead our high speed amplifiers team. Another engineer released or is releasing those last 3.
The following products were developed 100% specifically for audio: OPA1622, INA1620 INA1650/1651, OPA1678/9, OPA1692, OPA1656. The only device with a similar variant sold for other applications is OPA1656 (OPA2156). But the input stage architecture of OPA2156 is actually different, and it is laser trimmed. The two devices do not share a mask set.
The products are not on an "audio specific" process flow. They use our high voltage SiGe process fab'd in Germany, which is also used by a number of other HV bipolar amplifiers.
I can honestly say we never revised a product due to the results of a listening test. We did however make a revision on a product when I found behavior on the Audio Precision I did not like.
OPA1688 and OPA1671 do have non-audio variants.
OPA1637 is an audio version of a very high precision product called THP210 which is about to be previewed on ti.com. While high precision applications drove the specs of that product, I will say that I kept audio applications in mind while defining the AC performance.
Also, despite what I've read here, all of these developments made financial sense for TI and we're quite happy with the investment 🙂 And no, the cost of an 8 inch mask set is not prohibitive. I would argue that transistor feature size is a much larger factor in mask cost, and we're not building op amps on <45nm CMOS here...
OPA1688, OPA1622, INA1650/1, INA1620, OPA1678/9, OPA1692, and had started the OPA1671, OPA1656 and OPA1637 before moving to lead our high speed amplifiers team. Another engineer released or is releasing those last 3.
The following products were developed 100% specifically for audio: OPA1622, INA1620 INA1650/1651, OPA1678/9, OPA1692, OPA1656. The only device with a similar variant sold for other applications is OPA1656 (OPA2156). But the input stage architecture of OPA2156 is actually different, and it is laser trimmed. The two devices do not share a mask set.
The products are not on an "audio specific" process flow. They use our high voltage SiGe process fab'd in Germany, which is also used by a number of other HV bipolar amplifiers.
I can honestly say we never revised a product due to the results of a listening test. We did however make a revision on a product when I found behavior on the Audio Precision I did not like.
OPA1688 and OPA1671 do have non-audio variants.
OPA1637 is an audio version of a very high precision product called THP210 which is about to be previewed on ti.com. While high precision applications drove the specs of that product, I will say that I kept audio applications in mind while defining the AC performance.
Also, despite what I've read here, all of these developments made financial sense for TI and we're quite happy with the investment 🙂 And no, the cost of an 8 inch mask set is not prohibitive. I would argue that transistor feature size is a much larger factor in mask cost, and we're not building op amps on <45nm CMOS here...
National did develop parts specifically for audio: the LME series. I spent time with the product manage for the line and heard the details of the development. However the hard reality is that they have mostly been killed off which supports somewhat the issue around business potential.
Today's audio specific parts with $$$ potential are amps with on board DSP's and Bluetooth SOC's. Even those are becoming commoditized killing the profit potential.
AKM does have a golden ear on staff (I have met him) but that is an outlier as well.
Today's audio specific parts with $$$ potential are amps with on board DSP's and Bluetooth SOC's. Even those are becoming commoditized killing the profit potential.
AKM does have a golden ear on staff (I have met him) but that is an outlier as well.
Ah yes, 2015, when Chinese cell phone companies were putting OPA1612s and AD8397s into phones...we probably crossed paths without even knowing it!
A 7805, 7815, 317, 337 with a 0.1uF zero ESR (ceramic or film) directly at the output feedback pickup point is almost guaranteed resulting in oscillations.
John Walton's listening panel seems to find the LT1693/LT3015 pair as outstanding. Maybe your listening panel had blood transfusion from Matt Murdock. 😀
If anything killed the business of the National parts, it was National. Although I love the performance of many of those devices, I find the datasheets infuriating. 100s of distortion curves but none of the basic curves that an op amp datasheet should have. Maybe just get the spice model and simulate? Nope, most don't have spice models.
I pleaded with TI management after the acquisition and subsequent re-organization of those products to let me re-do the datasheets with full characterization and create spice models for them. But the LME op amps were put into another group...
Still pissed about the LME49810/30. Probably one of the best product ideas I've seen, but again lacking in supporting collateral for the product. And if customers can't use a part easily, they probably won't use it at all.
Ed what do you think, is this a case of profound quantum entanglement? These are the plots of noise from the OPA211 and OPA1611 data sheets. Looks like cut and paste to me.
EDIT - Sorry John but this does not look so good to the careful viewers.
Attachments
Last edited:
You really think a sane semi manu is going to touch a process for the sake of audio non specified changes (aka “sound”)? That’s the best joke I’ve heard lately.
I would think the 1963 would only be best for constant load applications. not dynamically changing load demands.
THx-RNMarsh
THx-RNMarsh
Last edited:
You just agreed a few weeks ago that LT1963 has crappy noise performance https://www.diyaudio.com/forums/the...blowtorch-preamplifier-iv-23.html#post6053063 Anyway, according to Markw4’s eventual comment, 7805 sounds better, whatever that means.
I don’t listen to regulators, unless I know in advance it could matter. In that position in a DAC, a 7805, LT1963, or the latest fancy LDO do not. Anybody stating otherwise is either delusional or a swindler.
My understanding was that all high voltage National parts like the LME49810/30 were sourcing from an outdated fab in Ireland, that could not be economically upgraded, so the decision was to close the fab. Since those outdated processes had no equivalent in TI, the whole range of high voltage LME products was killed. Happens all the time, and at the TI business scale the sales numbers impact was virtually zero.
LOL It probably is cut and paste. I didn't do the datasheet but why re-take the data, time is money. As I've said here many times before, there is a slight difference in the compensation scheme between OPA211 and OPA1611, but otherwise the parts are the same. Without giving away details, 1611 has slightly better distortion but slightly less capacitive load drive. It was a tradeoff.
There seems to be the perception that TI doesn't want you to know that there are precision versions of the audio parts. But the precision version is the MORE EXPENSIVE option. I'm perfectly happy if everyone wants to pay twice as much for a version with the input offset voltage laser trimmed 🙂
- Status
- Not open for further replies.