[rickcr42]

Quote:

Not at all. As I do not belive there is any direct financial linkage, I think the threads are "previous work", but whatever....

since when is "pcbs for sale" not considered financial linkage ?

when someone gives and opinion or offers help and there is no "link" to a product THAT is zero financial linkage.I do not know the planet,and it is not this one,where selling something is not financial linkage

 

[morsel]

I have no websites with storefronts or profit margins because I do not sell anything. I have never sold any pcbs or parts, nor have any intent to do so. I am not paid by anyone. I participate in community service projects to learn and have fun while contributing to the community.

 

[goodsound]

Ok lets see if we can get this back on track.

What supply and power requirements am I looking at for Class A v/s Class AB ?

Can you guys point me to some good LT1010 projects ?

 

[rickcr42]

Quote:

I have no websites with storefronts or profit margins because I do not sell anything.

bullsh*t


No way i am buying that one

Quote:

Ok lets see if we can get this back on track.

good idea.....


Quote:

Can you guys point me to some good LT1010 projects ?

first download the data sheet from LT,decide on your bias point and be careful here if this is for portable use.
High bias=rapid battery drain,then send me an email and I can give you a file with a "proper" front end

 

[Tomo]

Hi,

I think Goodsound gotta real good idea. I am absolutely interested in the discussion Goodsound started. I have no interest in whoevers' profit mergins or etc. (Especially because I hate to do what I do for my living for my hobby.)

Anyways, I have been reading the specification sheets on LT1010. I have a strong feeling now that it CANNOT operate stand alone without feedback. The specification says that you may operate LT1010 without feedback but with a coupling capacitor. (I think it means this set up give you DC offset.) However, on the same specification sheet, I saw two schematics with opamp-DC-offset-correction. This means I may be able to implement simpler DC offset correction so LT1010 can operate standalone.

What do you people think?

Tomo

P.S. Nonetheless, Rick and few other people do make some sense. Morsel, you built a board that people sell. And, you openly recommend your product. I don't think no one doubt your work is excellent. Whether you make "profit" or not is irrevent. People do not care about that. (Unless it's the tax day!) What people care is that your products are being exchanged for cash. From this, people expect that you the designer make money. To make it worse, in such situation, recommending your product becomes "commercial statement." ... Although you mean very well (that I absolutely am sure), that is not tolerated here. ... You might want to avoid directly referencing your own product, Morsel. Instead, stick with component selections and other technical expertise. I found your comments on those topics quite useful and oberved people appreciate those more.

 

[rickcr42]

Quote:

Anyways, I have been reading the specification sheets on LT1010. I have a strong feeling now that it CANNOT operate stand alone without feedback.

actually man it not only works "open loop' but is my second favorite buffer for following an already present gain stage or CD player that has a volume control.

My #1 is the LH0033 but that part is obsolete and though can be had would never recommend a hard to find part no matter how good it sounds (BTW-found a source that makes them but for military aerospace and not readily available in small quantities to the public

)

If you look at the actual signal passing part of the circuit it bear an uncanny resemblance to the also obsolete BUF-02 and can be brought further into class-a operation than any other monolithic buffer I know of.All the rest of the circuit "clutter" is support circuitry.

DC offset.

You have to remember this is not a "gain" device so any offsets you get are "static" and will not change unlike when you have gain and the DC componant increased along with signal and there IS a workaround that brings it up to world class and beleive it or not it was YOU that hipped me to it about six years ago !

You linked to a pdf file from Welborne Labs,the "kits and mods" file or some such and there it was-the Welborne Labs Headphone amplifier Kit !

Yup.LT1010 open loop buffer with volume control to set sensitivity

I run mine "hotter" and use enough heat sinking to allow for it with the end result of a class-A buffer that only crosses to AB on serious peaks where the volume is so high anyway not as important to be in A which rules at low level detail retreival.

The reason you see it mated to opamps all over the data sheets is it needs to see a low impedance to drive the input,Welborne showed the way with the jfet follwer : Hiz Z in,low Z out to buffer

 

[Tomo]

Oh I remember the kit you refer to. I will go check it out again. Thanks.

Quote:

You have to remember this is not a "gain" device so any offsets you get are "static" and will not change unlike when you have gain and the DC componant increased along with signal and there IS a workaround that brings it up to world class and beleive it or not it was YOU that hipped me to it about six years ago !

Don't remember doing that ... But then I don't remember lots of things like keys, cellphone, pens, coins, wallets ...

Tomo

 

[rickcr42]

Quote:

Oh I remember the kit you refer to. I will go check it out again

no longer there tomo.Use the "wayback machine" for an archived version or send me an email and i will send you the file

 

[Tomo]

Just figure that one out. ... I have it printed out and stored in one of my filing cabinets. No worries. I am sure it's there.

T

 

[peranders]

Quote:

Originally Posted by rickcr42 how about just getting invlved in the discussion instead of pointing to your own products folks.would be a nice change of pace considering the guy just wants to build his own amp

Rick, if you really think hard, you know what Morsel's and her pals projects are all about. You know this in detail in fact. She was pointing towards her stuff just for inspiration and I think most people here can make up their own minds about going further in their struggle to achieve anything. It's not a defeat to buy a readymade goodlooking professionally made pcb. Rather made do that but some people prefer to do their own pcb and also design. Most of the "commercial" stuff which are mentioned here are of good or even of very good quality, far deyond Velleman stuff (Europe) and american junk. A couple of people here have used TPA6120 as an example and with varying degree of success and I have reach success and am very pleased so far. I have not tested every possible combination of parts so my impression is one TPA6120 project.

Need I say that I support Morsel and her friends?

 

[peranders]

I have checked the datasheet for the LT1210 and it sure looks that it can produce good quality because of the current feedback design, and yes it can be used alone.... but.... notice the very high input bias currents. They must be handled with care in the design process. => lot's of offset voltage.

I have made four current feedback amps and I really like current feedback. Those with current feedback are QRV-03, 06, 07 and 08

 

[peranders]

Quote:

Originally Posted by rickcr42 The LT1012 is not meant for audio and while that alone does not preclude its use the dta sheet really does tell the tale.If you want to drive a servo motor for an automation or robot however,great chip,but only if it is heat sinked properly.The 1012 is also too high a drain on the batteries for portable use and finally...why do you feel you need a full 1 Amp current delivery ?

Rick, not very many IC's are ment for audio. They are ment for industrial applications but some of the indutrial demands are good for audio also. TPA6120 is a ADLS driver repacked as a headphone amp. High current capability is often positive and means that you use only a part of it's maximum capacity => low distorion. 1.1 A, 15 volt peak at 1 MHz, not bad!

 

[peranders]

Quote:

Originally Posted by rickcr42 The TPA is an map,not a buffer.I have four,have had them for over a year and still have not felt the urge to use them but others report good sound

The TPA is an amp with exceptional high output current, nearly in class with the LT1210 but of course with less power rating.... so it's also a buffer.

 

[rickcr42]

Quote:

so it's also a buffer.

TI calls it an amp so who am I to argue ?

My goals are to enlighten not confuse and if i send someone looking for a "buffer" but it is in reality a CFB amp or called an amp,and that person not experienced in searching out data they would have a rough time

 

[rickcr42]

Quote:

TPA6120 is a ADLS driver repacked as a headphone amp. High current capability is often positive and means that you use only a part of it's maximum capacity => low distorion. 1.1 A, 15 volt peak at 1 MHz, not bad!

It looks good on the surface until you actually pour through the detailed graphs.again not the whole story so it comes down to the listening which I did and for my personal taste,and it is only that guys,was not a "keeper".

Most of the ADSL chips look like seriously good audio drivers and when i ordered the ADI AD8000 driver was ready to be wowed but again was totally dissapointed in the final results.
there may well be a keeper in that bunch that someone has tried and is keeping a secret but so far i am batting 000 on it

the part about "audio chips" you are right.Most are designed as a general purpose "building block" which can be used where the specs say it is a good fit but the ones that move over to audio use are usually because some one some where took the time to do the heavy lifting and weed through all the "pretenders" to find the real deal.
The "pioneer" in this is Frank Van Alstine who even back in the early seventies used the best of what was available for his Dynaco Mods and AVA products and in FACT was the very first manufacturer to use a opamp/buffer as a headphone amp ! (AD743/BUF02)
The man listens and that means hours and hours of testing with music as the only way with the rest of us benefitting from the work.

I have boxes and boxes of chips that I thought maybe,just maybe this is THE ONE where I could find a combination that kicked a*s that no one else ever heard of but they are back in the box

The only "keepers" were the AD8397 which I got as a pre-production part with EVAL board,wired it up +6dB gain and the results so good with my Grados I popped in a box and is my portable ampo still until or if something better comes along.The other introduced at the same time is the AD8655 which runs at ridiculously low voltages and stil put out gobs of current but being a CMOS opamp it is not up to the sonics of the jfet/bipolar or all bipolar chips and i use it strictly for portable digital in AD converters and DA conversion analog stages where it kicks butt and even in a low power electret mic preamp running in at +30db the noise level is good.


two "finds" in thirty years is not much of a record

Dedicated audio chips other than power amps/digital DO crop up from time to time and that is the SSM series from ADI,a few from Maxim,The INA series from BB which could also be considered Medical field chips bast*rdised to audio,all the chips from THAT Corp. and a single opamp from National.


The rest ? Generic multi-use "plug it in and try it" chips.So many that no human has a shot at testing them all but the good news is most already tell you to not bother when you read the spec sheets.

On the buffer front my standard is the LH-0033 and LH-0066 (a BEAST !) with next in line being the "assisted" LT1010.

i say "assisted" because the input likes a low Z drive or you do not get the most out of the chip and why you see it mostly used with an opamp that has a low out Z either inside or outside the loop.The jfet front end gets around this.
Part ll is the class of operation.The LH series can be for all intent considered Class-a buffers and is why they sound so good even though on paper modern deices wipe the floor with them.Output current is lower than what a lot of modern opamps can deliver and that is the problem !

too many get hung up on the final delivery number and not the QUALITY of that delivery ! No normal opamp is getting even 40 mA in class-a output or it will burn up so when you see thse HUGE numbers you need to be aware they shift in class as the output power raises and in the end usually to class-B.

So the LT1010 looks mild in direct comparison to some of the "Super Op-amps" and when compared to many ADSL drivers plus every single other modern buffer but here is a difference.The 1010 can be driven class-a for almost its entire output range in the metal tab 5-Pin oackage by selecting a single resistor.This package also has terminals for DC blalncing for those who may need it unlike the DIP package which to me is a total waste of plastic.If i want limits then i would just as well use an opamp and a video CFB at that (AD811 still a goody

)

Many ways to skin the same cat but I am a "simple as I can do it" K.I.S.S. type of person who alwys chooses class-a operation when possible and depending on the end use just how much Class-a i can get.Obviously portable battery operation means reduction in requirement

rickster