Post pics of your builds.... - Page 442

Great work! Keep us posted.

That looks totally wicked! Very clever idea with the PS up top and behind

I'd love to see a matte royal blue powdercoat over most of the amp, with the "front" of the power supply lapped to a mirror shine to reflect the tubes - my humblest of ideas presented to the master, of course

Kerry, so very cool.

Thanks for the complements

Super Duper!

Singles op amp amplifier, my previous amplifiers have been for dual op amps. It is now after 10 hours of tweaking very quiet, I got all problems out of it and DC servo works so well, that DC offset is 0.6 mV. I have 1V DC on my source, X-FI.

I built it for ADA4898-1 specially, I used small resistors and tried to keep wires as short as possible. I also used first time in my DIY history SMD parts, 22 uF tantalums for decoupling op amps. I guess they keep things very stable. I have some high frequency noise still left, I don't understand where is that coming. I could try to search SMD ceramic caps and solder them on top of those tantalums. This starts to be quite sophisticated breadboard building. I start to be proud of my work.


Final problem was in this ground channel

I had some distortion in vocals and that area of freq range, and I was so desperately trying to find a solder bridge or some mistake from the main amplifier board, but just couldn't find anything. It took so much time.
I finally tried if op amp on ground channel was warm, and it was hot. It was oscillating. I took the input ground and op amp ground wires from its output and put them for TLE2426 to take care of. I also added a 10 uF tantalum across its supply pins. There possiby was also a solder bridge at its output. These measures helped and oscillating stopped and god at last it was so quiet (except very high freq noise which I am barely able to hear). Now I can begin to enjoy ADA4898-1 and soon I possibly solder ADA4627-1 to dip8 sockets and install them to this.

Those aren't compliments, Kerry, Those are statements of fact!

U da man.

I'm surprised to see those opamp's pins didn't short.

I checked those with multimeter before plugging in and they have no continuity. There is tiny space between the pin solder joints, it is difficult to see on these pictures. They are nothing but pretty, shiny and big, just the way I like them. I wanted to make mechanically solid joints, not just electrical connections.

I tested the THD of this amp with RMAA. It is 0.0052% unloaded. That is op amp superiority, skills don't matter so much to end result on such simple circuit.

I got some comments elsewhere on that build and people said that it is hideous.

At this stage when I just try out things, it isn't so important that things look great. I am pretty happy that I can manage such many connections and remember the component values without writing anything down.

Cause that little opamp is under a lot of mechanical stress?

Quote Spacehead: *snip*...At this stage when I just try out things, it isn't so important that things look great....


my early stuff was just plain ugly and has gotten only slightly better...

When I push it to socket multiple times it will be.

OK, there is a little too much solder. But why fix it when it works? I wonder if I could hear it if I removed some solder so that gaps between pins would be over 0.5 mm.

Mine has evolved too. There is only one resistor per op amp on the top side. And rest start to gather to the under side.

BTW. I took a 1K ohm resistor from old motherboard and matched it with another one and then soldered them into op amps sockets pin. It was feedback resistor to ground. Now feedback loop is again little shorter.
But it made THD worse. I used again too much solder.

Spacehead: You're a braver man than I, I'm too chicken to go the Surface Mount route. lol

I was reading on anther build that someone was using pin sockets to allow easy swapping of caps, I suppose this technique could be used for other components. Handy for prototyping a circuit without using a massive protoboard.

Bugger, I need a steady income so I can work on my killer amp.

I got so excited of using SMD parts that I did a TPA6120 buffer on breadboard to that singles amplifier. I used very tiny smd resistors and smd tantalum caps. I need to tweak it a little more and then I get a picture of that too.
SMT is so cool!

If you knew how horrible my equipment is , you would definitely dare to dive into SMT world
It is like through hole but requires a little more patience. It is actually faster to do on breadboard than through holes and less solder is needed.