I lost about 6 foam core speakers. All the amps are safe but the lab is turned upside down so no DIY for a while and I miss listening to my Class A Alpha and speakers already. Thanks for the encouragement. Mitigation crew removed all carpeting and installed blowers and dehumidifiers already.
GB Status update. I finally have the audio lab dry and partially functional. Still in reconstruction mode with new carpeting and drywall still waiting for installation.
Here is the list that I have so far for orders:
If I am missing your name or quantities incorrect, please let me know. Will try to pack the PCBs in padded envelopes today.
Here is the list that I have so far for orders:
If I am missing your name or quantities incorrect, please let me know. Will try to pack the PCBs in padded envelopes today.
Thanks for taking the time to get the boards mailed out, X. I was so sorry to hear about your flood. That’s something we dealt with often when I was growing up in the Midwest. Anything touching the floor usually ended up in the trash. Glad to hear you didn’t lose the important stuff and you’re recovering.
ahhh damn flooding sucks. happened to us a few years back because the drainage for our lot was blocked so water cascaded through our yard and basement. muddy electronics, meet the bin, and even pot plants were getting moved around the yard....
good to know the cleanup & recovery is progressing! I'm sure everyone will understand that that has to be your priority at the moment
good to know the cleanup & recovery is progressing! I'm sure everyone will understand that that has to be your priority at the moment
Verification build for PSU
I assembled the PSU and found a few typos in the schematic. The regulators are labeled A211 and A221, The positive rail regulator should be mounted in the position closest to the DC-DC converter (A221) and the negative rail regulator should be mounted at A211. The resistors on the cap Mx R231/R241 should be 10k and not 220R.
I had some trouble because of a bad batch of 7918 regulators. After trying 3 with no luck I installed a 7915 that I knew was good and it worked. So its is surprising at it is an ON Semi MC7918CTG from Mouser.
Anyhow, the circuit works but it looks like ideally we want to use the the nice LDOVR.com regulators with adjustment so that we can dial in the appropriate upstream voltage as there is about a 2.4v drop through the cap Mx.
I have it hooked up to a 10w 100ohm load (circa 150mA on each rail) at present and doing burn in.
So the PSU works if f you follow this revised schematic below.
I assembled the PSU and found a few typos in the schematic. The regulators are labeled A211 and A221, The positive rail regulator should be mounted in the position closest to the DC-DC converter (A221) and the negative rail regulator should be mounted at A211. The resistors on the cap Mx R231/R241 should be 10k and not 220R.
I had some trouble because of a bad batch of 7918 regulators. After trying 3 with no luck I installed a 7915 that I knew was good and it worked. So its is surprising at it is an ON Semi MC7918CTG from Mouser.
Anyhow, the circuit works but it looks like ideally we want to use the the nice LDOVR.com regulators with adjustment so that we can dial in the appropriate upstream voltage as there is about a 2.4v drop through the cap Mx.
I have it hooked up to a 10w 100ohm load (circa 150mA on each rail) at present and doing burn in.
So the PSU works if f you follow this revised schematic below.
Attachments
The PSU has now been tested with the amplifier (hand etched proto). Running at about 95mA bias current. The common heatsink for the 7818 and 7918 is at 60C. With adjustable LDOVR.com regs we can adjust voltage to about 3v higher to compensate for the dropout in the cap Mx, so overall dissipation on heatsink for the regulators will be about 50% less. Right now it is dropping 6v from 24v to 18v. Listening to it sounds great. Measured noise at headphone outputs with no signal input is 0.0mV to 0.1mV rms.
Ready to move onto building and verifying the main amp board now.
Ready to move onto building and verifying the main amp board now.
Attachments
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