[3amsleep]

Finally!, after a long time I had the time to finish my AD8066 based amp, and I have to say, I LOVE IT!.

The main problem was that the first prototypes tended to oscillate due to layout problems and the fast and power eating nature of the AD8066. The second problem was that I really wanted to start fabricating my own professional boards with the Silkscreen technique, so getting the inks, making the screens, learning to make the matrix and fabricating an effective isolation rig were pretty hard tasks to accomplish.

But!, I don't want to bore you, I'll tell you how it sounds.

[size=medium]The Sound[/size]

The sound on this puppy really amazed me when I first heard it, it's clear, focused, cool, fast, fairly detailed and the soundstage is really wide; I love it!.

[size=small]The Bass [/size]

The low end on this amp sounds really focused, but still warm, it can handle very fast changes of tone and dynamic and keep the bass supported and Weighty. Also, I noticed that the amp can handle to put out seismic bass with a truly amazing response for such a simple layout.

[size=small]The Mids [/size]

I was really amazed to hear such a detailed sound without getting harsh, I can really hear the different voices, guitars, synths, etc... sounding smoothly. I can also notice the bass/guitars picking and fretting noises on the background accompanied by other instruments details like piano keys.

The voices sounds great!, I wouldn't say they sound amazing, but the amp brings out the human essence on the voices, they sound alive and full of detail. I really enjoy hearing Chris Cornell's, Richard Patrick's and all the voices on Massive attacks Mezzanine thru this amp.

[size=small]The Highs [/size]

I think here is where this amp really shines, the sound stage is amazing, it sounds sweet and the texture is just lovely. I really don't know what else to say, I'm just so impressed with the sweet, warm highs of this amp.

[size=small]Overview [/size]

Ok I know it sounds like I'm crazy in love with this amp, but I have to say for the sake of trying to be objective; This amp is definitely not the best I have heard, but it's really amazing considering the price and low complexity. The sound is just lovely and very musical, definitely not harsh or tiring like the majority of other AD opamps.

If you like detail, powerful, but controlled bass, wide soundstage and warm sound, while keeping a low complexity layout and portability without expending too much, this one is for you.

If you're interested in building this one I can provide the schematics/PCB layout eagle files, just ask me =). I expended around $60 dollars in total on this amp, but I think it could be built for around $40 easily.


[size=medium]Extra Pics[/size]

this pics are from the silkscreen matrix that I made/used.

[size=medium]Schems/Layout[/size]

Of course you just substitute the OPA2134 for AD8066 (I used opa2134 because it has the same pinout and it comes by default with the eagle lib(yeah im lazy))

BTW I used a long shaft Alps STRK09707 pot, so thats why the PCB footprints are so far away from the edge.

 

[Zigis]

Quote:

Originally Posted by sickntired /img/forum/go_quote.gif It's a great portable amp, enjoy! The only criticism I have to the schematic regards the lack of reservoir caps in the split power rails.

You can replace C3,C4 with 100-470uf x 16V low ESR el caps, then under PCB solder 0.1uf film caps direct on el caps legs, or even better direct on chip power leg and ground

 

[3amsleep]

Quote:

Originally Posted by sickntired /img/forum/go_quote.gif It's a great portable amp, enjoy! Since the pot is low in value, and there are no DC decoupling caps, I bet you can even use the AD8397 without any problems (but do measure the output DC offset). The only criticism I have to the schematic regards the lack of reservoir caps in the split power rails. But probably for battery use it's better like that since the amp will tend to draw less current while playing.

thanks =), yeah im really enjoying this one.

I dont know about the AD8397, its a pretty cranky chip and it's nowhere to be found where I live, so I think i'll have to pass on this one.

Quote:

Originally Posted by Zigis /img/forum/go_quote.gif You can replace C3,C4 with 100-470uf x 16V low ESR el caps, then under PCB solder 0.1uf film caps direct on el caps legs, or even better direct on chip power leg and ground

Im not sure about how much improvenment will I get from reservoir caps on the split rails. I think the purpose of using them would be maintaining the stability of the amp when large loads are passed trough the amp (am I right?), but the amp is really stable now, I haven't been able to make it oscillate =).

 

[3amsleep]

Quote:

Originally Posted by 3amsleep /img/forum/go_quote.gif Im not sure about how much improvenment will I get from reservoir caps on the split rails. I think the purpose of using them would be maintaining the stability of the amp when large loads are passed trough the amp (am I right?), but the amp is really stable now, I haven't been able to make it oscillate =).

anyone???

 

[diditmyself]

I think the major reason to use caps from rails to ground in conjunction with TLE2426 is stability, not "power reservoirs", neither will it improve the crosstalk in the audible range much. The output impedance rises steeply with frequency. I think smallish caps will do about the same job as large ones. I've even had some instability issues when using large low ESR caps this way.

My advice is that you listen and find out for yourself. If you're familiar with Spice you could simulate it to see what happens.