Updates
Today I finished the VU meter "subchassis", that includes the VU meters, VU meter log drivers, clipping monitors, and heatsink temp monitors. It also includes the switching regulators (5V and 12V) for the monitor circuits, LEDs, and speaker protection PCBs.
I built this unit as a subassembly to ease construction. It also permitted me to test the "pure" F5 amp (finished today!), and also allows me to strip off the VUs, clip and temp monitors in the future, in case I want to revert back to the basic F5 amp without the "bells and whistles".
Some construction pics attached.
Again, the basis amp is completed and tested. I'm currently burning in the amp modules with 4 volts across R11 and R12. Temps are moderate--between the Conrad heatsinks and cooling fans, there are no cooling concerns. I will check further, as I button up the amp in the final chassis configuration, which places more reliance upon the fan cooling (and less use of traditional convection cooling). The VU subchassis (shown in the attached pics) has also been fully tested as an assembly.
I still have to research and identify an ultra-bright LED (160,000+ mcd) to replace the 5-watt incandescent bulb(s) that are used as the light-sources for the projectors in the VU meters. Might go to surface-mount, heat-sinked SMD 1-watt LEDs to do the job. (I'm open to suggestions!)
All that remains is final integration, resetting bias voltages, and full-up testing.
After that, it's just listening to beautiful music, as the fat lady sings....!
Today I finished the VU meter "subchassis", that includes the VU meters, VU meter log drivers, clipping monitors, and heatsink temp monitors. It also includes the switching regulators (5V and 12V) for the monitor circuits, LEDs, and speaker protection PCBs.
I built this unit as a subassembly to ease construction. It also permitted me to test the "pure" F5 amp (finished today!), and also allows me to strip off the VUs, clip and temp monitors in the future, in case I want to revert back to the basic F5 amp without the "bells and whistles".
Some construction pics attached.
Again, the basis amp is completed and tested. I'm currently burning in the amp modules with 4 volts across R11 and R12. Temps are moderate--between the Conrad heatsinks and cooling fans, there are no cooling concerns. I will check further, as I button up the amp in the final chassis configuration, which places more reliance upon the fan cooling (and less use of traditional convection cooling). The VU subchassis (shown in the attached pics) has also been fully tested as an assembly.
I still have to research and identify an ultra-bright LED (160,000+ mcd) to replace the 5-watt incandescent bulb(s) that are used as the light-sources for the projectors in the VU meters. Might go to surface-mount, heat-sinked SMD 1-watt LEDs to do the job. (I'm open to suggestions!)
All that remains is final integration, resetting bias voltages, and full-up testing.
After that, it's just listening to beautiful music, as the fat lady sings....!
Attachments
one hell of an amp , indeed .....
Yes it is.
Amazing attention to detail and second to none build quality.
WOW!
BBM3....but you missed the most important part: NO SMOKE (YET)....!!
Thanks for the complement. I'm off tomorrow early AM on business--so I really wanted to fire up the amp modules today (and I did, about two hours ago).
Will drop you a PM when I return. Since you're north of me, and 6L6 is further north (Denver, Aurora), a good meeting place might be around you, in Monument....(!)
Ken
Thanks for the complement. I'm off tomorrow early AM on business--so I really wanted to fire up the amp modules today (and I did, about two hours ago).
Will drop you a PM when I return. Since you're north of me, and 6L6 is further north (Denver, Aurora), a good meeting place might be around you, in Monument....(!)
Ken
I knew that 4V was a typo , but I couldn't resist ..... still trying to find my chair after laughing
regarding those satellites .... naah .... everybody knows that Earth is one flat plate ...... so I know that satellites are hoax
Just wanted to see if you were listening, when I typed 4 VOLTS. Honest. No kidding. Really. Trust me. (OK, OK, it WAS a typo!)
Agreed, that the earth is flat..... that's why it's even more fun to watch for satellites--as they fall of the edges.....!!
Calling Zen Mod. Come in Zen Mod. Can you hear me Major ZM, Can you hear me Major ZM?!
For here am I floating in a tin can far above the world;
planet earth is blue and there's nothing I can do.
Peace,
Dave
Houston, we have lift-off of another F5.....!
Set the initial biases yesterday (yes, ZM--they were set at 0.4 volts....!)
Brought up to 0.6 volts this evening, and let it idle for two hours. No surprises. Very well behaved. Minimal drift. Heatsinks probably a little too cool (Conrads, currently in an open chassis, with a low-speed muffin fan blowing across the back (flat) side of the heatsink base).
Pics attached.
The two small DMMs are showing the voltages across R11 and R12. (There was some minor variation--by swapping the two DMMs, a few mVs of this deviation was identified as variations in the DMMs themselves, later confirmed when I hooked both DMMs to a common low-voltage (0.7 V) source, and their readings differed by 4 mV. I can live with that.)
The larger DMM shows the output DC offset, which varied between 0.1-0.2 mV over the two hour period. 40-MHz scope showing no oscillations.
I can hear the "routund lady chanting" now....
I still have to finalize the front panel and engraving, fabricate the chassis top and left/right side panels, and then I can call this build a success..... (I hope I'm not speaking too soon.....!)
Set the initial biases yesterday (yes, ZM--they were set at 0.4 volts....!)
Brought up to 0.6 volts this evening, and let it idle for two hours. No surprises. Very well behaved. Minimal drift. Heatsinks probably a little too cool (Conrads, currently in an open chassis, with a low-speed muffin fan blowing across the back (flat) side of the heatsink base).
Pics attached.
The two small DMMs are showing the voltages across R11 and R12. (There was some minor variation--by swapping the two DMMs, a few mVs of this deviation was identified as variations in the DMMs themselves, later confirmed when I hooked both DMMs to a common low-voltage (0.7 V) source, and their readings differed by 4 mV. I can live with that.)
The larger DMM shows the output DC offset, which varied between 0.1-0.2 mV over the two hour period. 40-MHz scope showing no oscillations.
I can hear the "routund lady chanting" now....
I still have to finalize the front panel and engraving, fabricate the chassis top and left/right side panels, and then I can call this build a success..... (I hope I'm not speaking too soon.....!)
Attachments
Thanks, Melon Head and 6L6.
The music will come tomorrow night, but first--critical decisions! Classical, or smooth jazz? White wine, or red? Ahhh, such choices!
Melon Head--I recall your earlier Email, regarding temperatures. Ultimately, I may not need the fans on all the time--perhaps only in case of a meltdown. (Sorry, poor choice of words, there--meltdown....)
Ken
The music will come tomorrow night, but first--critical decisions! Classical, or smooth jazz? White wine, or red? Ahhh, such choices!
Melon Head--I recall your earlier Email, regarding temperatures. Ultimately, I may not need the fans on all the time--perhaps only in case of a meltdown. (Sorry, poor choice of words, there--meltdown....)
Ken
Going higher on bias??
Melon Head--I recall you stating you had gone as high as 2 amps idle current on a straight-forward F5 using the Conrad heatsinks.
If my heatsinks (and fans) continue to run relatively cool, is it feasible I can raise my idle current? Right now, I can keep my fingers on the heatsinks indefinitely (i.e., easily passes the "Pass five second rule-of-thumb"), and I suspect my heatsink temp is only about 40 C. I'm running mica pads and Arctic Silver for my "goop". Granted, this is in a relatively cool basement workshop.
I think my PSU is adequate for some increase (500 VA), and I'd almost like to run the MOSFETs warmer, in search of the "sweet spot".
Your thoughts? What ultimately should be the determining factor? The MOSFET temperature (and heatsink temp)? Limitations (and caving voltage) of the PSU?
Thanks....!
Melon Head--I recall you stating you had gone as high as 2 amps idle current on a straight-forward F5 using the Conrad heatsinks.
If my heatsinks (and fans) continue to run relatively cool, is it feasible I can raise my idle current? Right now, I can keep my fingers on the heatsinks indefinitely (i.e., easily passes the "Pass five second rule-of-thumb"), and I suspect my heatsink temp is only about 40 C. I'm running mica pads and Arctic Silver for my "goop". Granted, this is in a relatively cool basement workshop.
I think my PSU is adequate for some increase (500 VA), and I'd almost like to run the MOSFETs warmer, in search of the "sweet spot".
Your thoughts? What ultimately should be the determining factor? The MOSFET temperature (and heatsink temp)? Limitations (and caving voltage) of the PSU?
Thanks....!
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