at ~55mV on each resistor on one channel, supply voltage holding steady at 26.15 +/-
Am I good? Up to 73mV across each side, 0.01 offset, supply voltage still holding steady around 26v. It seems to be doing okay, it doesn't stink or anything.
Edit2: heatsinks are starting to feel above ambient.
Edit3: we have amplification on the scope. If there are no abrupt objections to 26v rails, I'm gonna keep adjusting and playing.
Am I good? Up to 73mV across each side, 0.01 offset, supply voltage still holding steady around 26v. It seems to be doing okay, it doesn't stink or anything.
Edit2: heatsinks are starting to feel above ambient.
Edit3: we have amplification on the scope. If there are no abrupt objections to 26v rails, I'm gonna keep adjusting and playing.
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Yep, I've been practicing this little dance back and forth, the trick seems to be to get it close and give it a second to settle. Up to about 75 on each side. I probably won't go much higher than .08 or .09, I kinda want it to have that distortion profile nice and thick.
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I was joking around when I origionally posted this heatsink and asked how much bias I should be able to throw at them, but man, we're up to 90mV on each side and we're barely over body temp.
I salvaged these heatsinks out of an 80s electro voice amp, I guess they're pretty good!
I salvaged these heatsinks out of an 80s electro voice amp, I guess they're pretty good!
Dennis is correct, your bias is very low, see below I copy/pasted a part from Papa’s paper
¨My estimated maximum dissipation of each of the two output devices per channel is about 35 watts, so given my default +/-24V rails, I have calculated the maximum bias for each channel, which range from 1.1 to 1.4 amps. The bias is measured across R6 or R7, and is calculated, Voltage / 0.47 = bias amps For 1.1 amps the voltage is 0.52V and for 1.4 amps it is .80V.¨
So with 0.075V it’s far from 0.520V to 0.800V (I believe it’s 0.660V)
Thanks
Eric
¨My estimated maximum dissipation of each of the two output devices per channel is about 35 watts, so given my default +/-24V rails, I have calculated the maximum bias for each channel, which range from 1.1 to 1.4 amps. The bias is measured across R6 or R7, and is calculated, Voltage / 0.47 = bias amps For 1.1 amps the voltage is 0.52V and for 1.4 amps it is .80V.¨
So with 0.075V it’s far from 0.520V to 0.800V (I believe it’s 0.660V)
Thanks
Eric
I went ahead and snagged another kit with dual power supplies. So, I have an extra kit and power supply to build sister
one too. Or sell if shes not interested. I guess I could have just bought a single set to go with one I have, but it drives me crazy
if both sides arent same, same caps etc.
Russellc
one too. Or sell if shes not interested. I guess I could have just bought a single set to go with one I have, but it drives me crazy
if both sides arent same, same caps etc.
Russellc
We're making music!
It started to get a little hot for my liking, so I've got the bias down around .50 for now, until I figure out a fan.
Also, compared to my other amp, this needs a lot more signal..I might need to have a fiddle with the input resistors, my sub amp has to be down at like 9am on the knobs, and a spirited listening session has my freya volume knob leaned over at like 4pm.
It started to get a little hot for my liking, so I've got the bias down around .50 for now, until I figure out a fan.
Also, compared to my other amp, this needs a lot more signal..I might need to have a fiddle with the input resistors, my sub amp has to be down at like 9am on the knobs, and a spirited listening session has my freya volume knob leaned over at like 4pm.
If you are getting all the volume you need on your speakers, then why fiddle? Volume control just looses gain in preamp. If preamp is going full out without attenuation, then volume pot is effectively out of circuit except for loading, so presumably one is minimizing additional distortion?
I am not sure that reducing input gain of the amp will result in the amp functioning in a better operating zone.
No harm in trying though, except possibility of creating an error or defect when desoldering input resistors on amp.
I am not sure that reducing input gain of the amp will result in the amp functioning in a better operating zone.
No harm in trying though, except possibility of creating an error or defect when desoldering input resistors on amp.
I'm sure I can do it without hurting it, I have a desoldering station, hehe.
The biggest issue is, I'm like 2 clicks away from the maximum on my pre, and it's way far off from the input sensitivity of my cary sla-30, and I'd like it if it was similar, I believe the sla-30 requires about 0.7v of input to reach full output, and on my pre, that puts the volume knob between noon and 3pm-ish when I'm crankin tunes.
Right now, for the same level, I'm leaned right over almost on the stop of the volume knob. I need a little more room than that.