[Tomo]

Hey, you all.

It's been say ... 2-3 years? But now my needs changed, I need to forgo my YAHA amp and Szekeres amp. Also my souped up CMOY amp is too high gain for my new CDP and Computer output. So this give me excuse to build a new one.

I was thinking going uber is a nice change as I can afford now. ... But I realized I have completely forgotten how to deal with those uber components. So CMOY amp all over again!

But I am already done with PSU. It's from my previous project.

I am busting out my amp boards here to put in CMOY amp.

Good bye, THS4022EVM. Here I come OPA132/4. Yep you all remember those. This time, I am covering more details. Hehe. This will teach me stuff as well as to boost my ego which is short supply now.

After that, I can try out Grado RA1 setup with 4556. Yep, I have those. I also have some 5532/4.

Probably I should do surf mount opamps too. But I don't know many so please suggest.

This week, I am doing inventories. Geez, this might take a few days. Oh so you got some suggestion on components plz suggest. (Not on design please. We will discuss that after this project. ... why? because I wouldn't know whatcha talking about.)

T

P.S. I have been doing finance work. ... You know stocks and bonds. When I close my eyes I see yield curves. This must be stopped at all cost.

 

[Tomo]

Woot!

Bypass caps gonna be 0.1uF Cera and 100uF OSCON. So we start our discussion here. We can also talk about the ground snubber circuit on the above picture.

Thanks in advance yal. T

 

[Tomo]

Hey,

Anyone remember AD797 can be operated in simple negative feedback mode? The specs don't tell me about the current capability.

Oh and one more thing. Has anyone know anything about BUF602? It's supposed to be a closed loop buffer. You know what this means right? I don't need no feedback. Kinda nice way to start with the idea of 0dB amp. (Szekeres is good, but I don't really want hot amps in Tokyo. It's steamy.)

Thanks.

T

 

[TzeYang]

don't drive capacitive loads well. Don't bother unless you have scope.

Needs buffer.

 

[Tomo]

That's a bummer. I guess that one is pushed over till the next project. (I do have BUF634s in my bucket.)

Anyways, I got my breadboard ready. I will need to build another set for SMTs but that's for later.

I had thick copper wire in my box. I got rusty, then again I wasn't really good to begin with. Now I have to start calculating stuff.

T

 

[Earwax]

Quote:

Originally Posted by Tomo /img/forum/go_quote.gif That's a bummer. I guess that one is pushed over till the next project. (I do have BUF634s in my bucket.)

Best left in the bucket, IMO.

I have also come back to DIY after an absence, one change I am glad to see is that 634s are no longer in fashion. lmh6321 is a reasonable replacement and there are also some discrete substitutes that are somewhat popular http://www.head-fi.org/forums/f6/mon...er-pcb-345035/

 

[Tomo]

Hehe, you know me, Earwax. I am heading in that descrete way. This time I am taking one step at a time.

 

[Tomo]

Hey,

I did my calculations. It is a sorta compromise as my needs and options restrict values.

I have two hundred 11kohms resistors. So I use R3 = (1/11kohm + 1/11kohm)^(-1) = 5.5kohm. This gives me G = (1 + 11kohm / 5.5kohm) = 3.

A little bit compressed, but I really don't need much more gain. (Multi-loop is the immediate next step in the project.)

Problem now is that the volume pot is 120kohm stepper, but it is linear. Anyone got a good idea as to simulate log with it? I know parallelling with a single resistor will do it, but I would like to know any more interesting ways. I could also do Shunt-Type, too. Let me compute the values. ...

T

 

[Tomo]

I found this.

Has anyone tried this one? It seems like this is more economically plausible. (I get good deals when I get 100 of one particular value.) Yeah, I could actually do logarithmic setup, but then it would be considerably more expensive. (For me, 10 times more expensive. Bulk price is really low; stores are trying to get rid of stocks now.)

T

 

[Tomo]

Hey,

I am done. Lookie this.

The CMOY amp is stacked; two floors.

It is a real OPA132 amp. Authentic! Haha.

Only real problem is that input cap is slightly distant from the OPAMP pins. This make it vulnerable to pickup, so you all avoid this. But then I am not getting any right now. I ought to have used a bigger board or something. But for now, I enjoy.

T