MASantos

Done! Neutrik 4 pin xlr mounted from behind with blind taps. all in all went well considering it was done all with a hand drill. No drill press around 😔 The on/off indicator led was mounted underneath the case, makes for a nice effect. Quite happy with the result! Now the quest for a better streamer starts!

Thanks! I've listened to the CFA and dynalo mini for about 2 hours this afternoon trying to compare them. I liked the cfa better I believe but will keep listening. They are both great amplifiers but I can only keep one.

What is the SS/ZF thing?

I have about 160mA bias atm and the heatsink is about 34 Celsius. Transistors are about 10 C higher. I'll push it a bit closer to 180-200 once it is all done to see if it makes any difference.

The case is alright. Not top notch but also not a bad price considering it has most of the drilling done. The whole for the switch is 13mm wide with a little bevel on the front. The cap on the pushbutton didn't fit right so I made that cosmetic upgrade. I am considering painting the front panel mate black.

It's alive! Finished wiring today, only thing missing is drilling the front panel for the 4 pin XLR, waiting on a drill bit. Probably the best amplifier I had for the HD650. Absolutely dead silent, great sound! I'll need to make a better comparison with the dynalo mini, but at first glance it sure seems like a winner. Thanks for all the help I got during the build!

So when I got my case I got pretty upset with the looks of the power switch: So I search around the house for what could be used to improve this and found and unused aluminum kitchen drawer handle. Nice looks, hollow and easy to cut. A couple of minutes later:

That's reassuring! Mouser forgot my opamps. They're in transit as we speak. Regarding biasing, I have about 190mV across the 1ohm output resistors, heatsink is around 40 C . What is the target for biasing?

Did the diode across the board and found some discrepancies in the input pair. Replaced both critters and voila. Board is biasing normally, both LEDs are shining. 60mV of DC offset on both channels with inputs shorted. Will finish wiring inputs output while waiting for servo opamps.

Thanks for the tip.Will do it tomorrow and report back.

So I cleaned the boards once again and checked every transistor for orientation and location. Both boards match. 4 LEDs appear to be ok, similar voltage drop. I powered both boards and took some random VDC readings to ground. This is where things show that something is wrong. Most of the small critters have different readings. They all came from the same 100 unit strip bought from mouser. I guess I'll go ahead and start replacing them all.

I cleaned the flux with 96%alcohol and a tooth broth. There are only a few spots left. I did check the orientation and parts but will do it again later today after clearing my head from it.

So I wired the amplifier board to the GRLV. One channel fires up ok. Both leds giving light, about 150mV across the output resistors 90mA offset without servo and input open. On the other channel I have one of the LED not lighting. No reading on output offset. all the LEDs test ok with a multimeter I diode check and emit a small light. On the mjf15030, the output resistor reads 30mv across. On the 15031 nothing across the output resistor. I don't see any solder bridges. Should I start replacing stuff?

Apparently mouser forgot to send me the opa134 needed so I plugged a pair of opa445 for the CFA servo. No smoke. Voltages are +25.02 and -25.11 I didn't match any of the LEDs or resistors so this seems pretty good to me and probably won't make a difference in real life.

I had the under switch in my power amp, but this one wont have feet high enough to reach under. I'm ordering a latching anti vandal switch and will be using a 4 pin xlr even though the amp is single ended. I already have my hd650 with a balanced connector so I wont have a need for adapter cables.