Amp4 -HV build

[sleepyhead]

Hello I believe you have gotten some of the bad chips floating around out there, check This thread. You have the same serial as the fakes

Hope you can get it working soon

//Makruzz

Thanks. I saw that before I made purchase but took my chances anyway. I just ordered more chips off ebay this time. Hopefully some good ones. I want this amp bad enough I'm willing to suffer some losses in the process.

V-bro thanks for your help, not just for my stuff but everything you do on the forums here. You're a real trooper you are!

[V-bro]

I'd perhaps deviate to the STA516B unless you are 100% sure it's a good batch.... It's almost the same chip....

By the way, Farnell also has the STA517B and I think it is a good batch....

Thanks for the heads up Sleepyhead! Just enjoying helping out and doing some pioneering!

[sleepyhead]

The excitement builds. Never good to get too excited because causes to do dumb dumb things! Nobody here ever does dumb dumb things do they? Haha. I got the new 517b chip from eBay. Soldered in, amp powered on. I start low voltage and raise slowly. Voltage holds and current stays normal. No sound. No relay click. Grrr. Measure voltages. All good. Got 9v. Got 5v. Then I notice what a dummy I am. No unmute jumper! I put on the jumper and try again. No sound, no relay. Arrrgh. Amp is at 52v. Hmmm. For some reason I decide to lower voltage. Click goes the relay and music from the speakers! Yea! Remember the 357k r52 & r54? Vpp sense is too low. It came on around 30 something (can't remember) and went off at 49v. I simply disable Vpp sense since I didn't have any higher resistors to use. R52 is 20k and r54 open...

It's ALIVE! It works! No full volume test yet as my supply isn't powerful enough.

Here's my test rig. Not the greatest setup but I don't lose any sleep over it. I just used pre-existing holes for temporary heatsink mounting. The extra capacitor is just a guess. The relay will probably close without it. (1.5K res)

LivingAmp.jpg

R6 I use 33 ohm. (another guess) 33 ohm only drops the supply 1.5v Poor 35v C50 taking 50+ Volts! It didn't blow! Me dummy! 470 ohm may be better choice but I won't do it. R6 is temporary. Leave it out. I'll feed the Vreg and C50 with a separate low Vs in my permanent install.

ps Thanks for the Farnell suggestion. May use them in the future.

[sleepyhead]

Having trouble. Need help.

Amp is connected to li-po battery at 58.6v. Yeah, I'm pushing it. Battery won't go any higher than so I "should never" fry the amp. That's fresh charge, most of the time it should be 52v to 54v. However the amp won't come on. My test power supply maxed out at 56v so I couldn't test any higher before running amp on battery. Amp comes on momentarily when I cut power. Chirp of music. So it does still work. I have Vpp sense disabled but I think my problem is an over voltage problem. I'd like to discharge the battery but have no suitable load. Money is already spent on battery so I have to use it. I don't really want too but should I bypass the relay? Is there anything else to do to make it run while battery V is so high?

Edit:

If anyone's interested. Got the battery drained enough to lower Vin to 57.4v and the amp came back to life. I knew it wasn't damaged. Back in business. Now I know it's tested tough. Solid.

Just for the record. I realize the very high voltage into 8 ohms isn't the most ideal setup but it's what I wanted to do. I knew going in that it would be easier and a little more powerful to run 42v and 4 ohm speakers. But hey, now you know, and that's got to be worth something. Besides, I like my 8 ohm speakers. As is it gets hot. A 112 x 112 x 15mm heatsink is not enough.