Diamante -a discrete medium power opamp

MrMajestic said:
Here are the assembled boards. Looking pretty good if I may say so myself 🙂 I havent powered these up yet, but I will soon.

An externally hosted image should be here but it was not working when we last tested it.


Great work!

A couple things to do before you apply power:

1) Set the bias pot (configured as a rheostat) to maximum resistance (measure across the outer pins), so you can adjust the bias upward later.

2) Remember to set the offset pot to the mid point (equal resistance from the center pin to each end) to start so that the offset is not wildly one way or the other.

Then on power up adjust the bias up to the desired level.

Then adjust the offset pot until the offset is at 0V.

Cheers!
Russ
 
I received the LCBPS from TP today, thanks guys 🙂 Going to assemble it tomorrow. Im going to take this opportunity to reach out to both Ryssen and Nelson Vandal : Are you still wanting boards, because you dont reply to my emails!! I need someone to build the first batch of boards besides myself.
 
KLe said:
Hi Russ White

How many watts does the Diamante produce?

🙂


With the BC550/560 as output devices it will be limited to ~ 1W but don't expect stellar THD at those levels. 🙂 It pimarily designed for headphones and as such it should rarely need to push more than 100mw or so. 🙂

If you used a couple of TO-220 devices, you could tweek the cct to do something like 5W pretty easily, even more if your creative. 🙂

Cheers!
Russ
 
robmil said:
Hi

if it is primarily designed for headphone use, will it be any good as a line stage with a gain of approx 12-16dB ?

rob


Absolutely, it makes a great line stage.

The lighter the load the lower the distortion.

Distortion will be very very low at > 1K load.

In fact if you know you will be using it as a preamp/buffer into load > 1K you can use just one of the output device pairs.

Cheers!
Russ
 
I'm sorry, I didn't answer your mail. Hotmail put it in the trashmail. The price is too steep to me. Since I always want active ground, I'd need 3 boards. Just the boards, pots and connectors would make it an expensive amp. Besides I've just ordered 10 boards for my folded cascode headphone amp, so I'll have too many boards lying around.

I'm glad too hear it turned out to be a great headphone amp. The Head-Fi people are so conservative, and it's always good to see novel ideas.
 
nelsonvandal said:
I'm sorry, I didn't answer your mail. Hotmail put it in the trashmail. The price is too steep to me. Since I always want active ground, I'd need 3 boards. Just the boards, pots and connectors would make it an expensive amp. Besides I've just ordered 10 boards for my folded cascode headphone amp, so I'll have too many boards lying around.

I'm glad too hear it turned out to be a great headphone amp. The Head-Fi people are so conservative, and it's always good to see novel ideas.

Too bad, it would have been easier to send the boards withing Sweden. If there is a group buy then the boards will be a lot cheaper.
 
Hi MrMajestic,

Correct me if I'm wrong, but it seems (from the image above) that you wired right amp psu connection from left amp psu connection. If that is the case, your wiring is wrong, you have to wire each headamp psu connection from the main psu board, otherwise you may have issue with ground loops.
 
aparatusonitus said:
Hi MrMajestic,

Correct me if I'm wrong, but it seems (from the image above) that you wired right amp psu connection from left amp psu connection. If that is the case, your wiring is wrong, you have to wire each headamp psu connection from the main psu board, otherwise you may have issue with ground loops.

Well, its wired the same way Russ did his prototype and I dont have a ground loop problem. I dont really see how this wiring scheme would create a ground loop, but maybe you can enlighten me.
 
Hi Mr Majestic,

It is better to wire the power to each amplifier direct from the PSU, and not daisy chained as you have it.

If I did it that way at one point it was probably temporary just to test the amp, I would have corrected it in a final installation.

Still what you have done probably would not cause any practical issue.

Great work! Very glad to see it working.

I am also very pleased you like the sound.

Cheers!
Russ
 
This is not the final setup, so I will wire it differently later. It was just convenient to do it this way. I might go fully balanced with it if no one is interested in the boards. And if no one builds the first boards, there wont be a group buy, at least not initiated by me. So please, step up to build the prototypes 🙂