[goodsound]

What is the lowest single supply voltage that the LT will work (and sound good) ? I was also thinking about the BUF634T (the to-220 pack), unless you have already tried it and dont think favourably of it.

It seems like the buffer implementation is so simple I am almost tempted to just build all three (LT1010, BUF634T, LT1210) and see what I like. There's only one problem. Although I have a lot of electronics/audio/radio (ham) diy projects under the belt I am still very unfamiliar with the deepest intricacies of the OPAMP. My first opamp project was a LM1875 mono amp which I am almost about to finish. I am still climbing the learning curve - though without much difficulty and fast. So I wouldn't know what would be the best configuration or supply voltage for those buffers. Thats where I need your help.

If you guys are interested, throw in or discuss some ideas and we can come up with some suggested configurations for these three bad boys and we each can see what turns out.

I am just simply attracted to the idea of a "buffer-only" headphone amp because I believe thats all that is needed. Ofcourse with a gain control at the front end or maybe just a fixed resistor switchable attenueator.

BTW, all this for a Grado SR-80.

 

[rickcr42]

Quote:

What is the lowest single supply voltage that the LT will work (and sound good) ? I was also thinking about the BUF634T (the to-220 pack), unless you have already tried it and dont think favourably of it.

Actually I think highly of the BUF634 and especially so for low voltage portable use.
The LT1010 can best it but only when you get it groovin' to higher currents and like with the bandwidth set pin on the BUF634 the set parameters have a definite 1:1 relationship to battery drain so is always a comprimise between ultimate sound vs how foten DO you want to change the batteries

You can get the LT1010 to operate down to the +/- 3 volts range but that is not a pretty picture (as it would not be with MOST chips that can but should not be down that low) and from memory the BUF634 works down there also but again,should not

A single nine volt batery works for either if you use a polaity splitter (artificial ground) but on the personal preference fron I always use dual nines for all my portables and even go to the external battery pack stuffed with 12 AA batteries often !

WAY more current than any nine volt battery could ever hope for

Simple "quick and dirty" portable buffer :

Audio signal section-

47K input load resistor (50k pot if you need a volume pot)
1K series resistor from input to buffer input
10 ohm series "build out" resistor from buffer output to output jack

Power supply section-

10uf Vishay Tantalum "slug" capacitor right at the +/- pins of the buffer
0.1uF AVX stacked film ceramic capacitor right at the +/- pins of the buffer
220uf low ESR electrolytic cap-at the batteries


Use the power tab version of either the TI or LT bufer and use the biggest heat sink you can fit in the casing.Run the BUF634 "low" bandwidth for portable use only or wide if it is to be a dual use home/portable buffer (wide means batteries drain faster but it sounds better

) and I beleive (from memory man...) 27 ohms to set the bias current on the LT1010 though it may be higher,like upper thirties even low forties but will have to get back on that one

Oh yeah.if you use a cast aluminum or other thick metal chassis then you do not need a heat sink.Just use isolation for the buffer and use the entire chassis as the heat sink

 

[Tomo]

Hi Five, Big-R!

Ciao,

T

P.S. Now ya'l behave.

 

[rickcr42]

Quote:

P.S. Now ya'l behave

You are an evil man Tomohiko

that is the schemo !

I almost want to say it is an Erno borbely design but I am not positive.What I AM sure of is the jfet front end cures an drive/matching problems inherent to the buffer and relaxes the need for an opamp at the fronty end ehich would 100% defeat the purpose of having a class-a buffer

I think you may (if you build it) find this is almost too good sounding for the level of simplicity kinda like the Szekeres Amp but far less power supply sensitive so an "any man/woman/person" build even on a perf board

 

[peranders]

Quote:

Originally Posted by goodsound After weeks of trying to determine which direction to go for building a headphone amp, I have finally narrowed it down to these two chips - One is a complete solution (TPA6120) whereas the other is a output buffer(LT1210). What I am looking for is a simple, compact/portable headphone amp. If its the LT1210 then it would have to be a "buffer-only" amp, no other driving stages please. So which one should I go for ? Has anyone listened to both ? Any suggestions you could provide for helping me make the decision would be highly appreciated! Thanks! <edit:> I will be using it with a Grado SR-80 but that is not a constant. It could change to another headphone down the line. And I will be using it with a variety of sources (Sound Card, PDP, PCDP, DAC, CDP)

Mister, it may be an good idea to draw up the specifications first

Specs:
How much gain?
Input impedance (are you going to use a pot?)
Output impedance? 100 ohms?
Output voltage?
Supply voltage, single or dual?
Current consumption, battery life?
Distortion, how much?
Noise, how much?

Can you fill in here?

Despite all that I find the LT1210 very interesting but why don't you test to build a very simple discrete current feedback amp with low current consumption.

 

[rickcr42]

data sheets for all parts are easily downloaded from the manufacturer sites but specs tell nothing about sonics and never have.

I have a 200Wx5 home theater receiver that claims .01% distortion yet sounds so bad to me I pawned it off on my son (scored big dad points

) and replaced it with a 40WPC EL34 Pentode amp that whips its a*s in everything but ultimate power output and all at1% distortion

Live through specs and you will think the LM386 is the equal of a OPA627

 

[Tomo]

Hey,

Hows this?

Can I not use JFets? JFETs make me remember those dreaded EE labs ... we measured everything and swapped a JFET by mistake. We almost failed ... Bleh!

Quote:

I have a 200Wx5 home theater receiver that claims .01% distortion yet sounds so bad to me I pawned it off on my son (scored big dad points )

Sir, you are evil. I am humbled. ...

T

 

[peranders]

A pcb for LT1210....
http://www.audio.webd.pl/projects/lt1210_pre.html

 

[Tomo]

Sorry.

All my buffer projects are stand still now due to sudden out-flux of Tomo-Assets. My computer blew in my face and had to get a new one. (Wicked Cool Cube-type. I got carried away. ...)

But will post as soon as I do the Szekeres Amp.

T

 

[rickcr42]

Quote:

All my buffer projects are stand still now due to sudden out-flux of Tomo-Assets

I definately know that feeling

Quote:

My computer blew in my face and had to get a new one.

And that.Blew mine up last august

Quote:

But will post as soon as I do the Szekeres Amp.

and still to this day my szekeres is one of the most musical amps in the house,sounds way better than it has a right to