clarify said Iq and DC Offset, relation
9mV is more than good, regarding DC OFfset
is there any problem with obtaining higher Iq, or you just stated that it's set to 140mV/0R11 in this moment?
hope you did elevate entire shebang from bench, fan need space in front to suck air
9mV is more than good, regarding DC OFfset
is there any problem with obtaining higher Iq, or you just stated that it's set to 140mV/0R11 in this moment?
hope you did elevate entire shebang from bench, fan need space in front to suck air
Yep elevated. Only took it to 140mv/0R11. Could only adjust offset to 9mv. Could not find my second DMM but had power to the board for 3 hours and it was iq and offset were stable.
The data sheet for my heatsink states it is 0.05c/w and I think it was only doing 0.22c/w. I could not feel much airflow.
The data sheet for my heatsink states it is 0.05c/w and I think it was only doing 0.22c/w. I could not feel much airflow.
offset is good
what you have is certainly not optimised setup - fan position with that hsink
you need sort or buffer volume in between heatsink fins and fan
from experience I know - that sort of fans is needing some space (especially on output side) for proper airflow
try inserting at least 50mm long tube/whatever in between fan and box
and yes, at least 3'' fan elevated from bench
hsink data - 0.05 - yes, why not, but be sure it's with some proper 230Vac roaring fan
what you have is certainly not optimised setup - fan position with that hsink
you need sort or buffer volume in between heatsink fins and fan
from experience I know - that sort of fans is needing some space (especially on output side) for proper airflow
try inserting at least 50mm long tube/whatever in between fan and box
and yes, at least 3'' fan elevated from bench
hsink data - 0.05 - yes, why not, but be sure it's with some proper 230Vac roaring fan
Only got 5mm gap between fan and heatsink. I didn’t expect 0.05c/w as I have the fan almost running silent but I think it can be optimised with your suggestions and some tape.
I will take it up to 180mV and see what the offset looks like. I will also read this thread again as it has been a while.
Thanks ZM
I will take it up to 180mV and see what the offset looks like. I will also read this thread again as it has been a while.
Thanks ZM
I tried the iq from 1A to 1.8A offset remained at -9mV throughout. I think it was at -9mV yesterday but the minus sign on the DMM is tiny and I did not notice.
At 1A the heatsink is almost room temp on one side and 12c above on the other. How many watts will it put out with a 35v supply at 1A and also at 1.8A. My speaks are Celestion Ditton 25’s. I don’t listen to music that loud, haven’t turned my Aleph J above 3/4 volume.
I also checked the ac at the output (LS+ and GND) and was reading 3mVAC. Is this noisy?
At 1A the heatsink is almost room temp on one side and 12c above on the other. How many watts will it put out with a 35v supply at 1A and also at 1.8A. My speaks are Celestion Ditton 25’s. I don’t listen to music that loud, haven’t turned my Aleph J above 3/4 volume.
I also checked the ac at the output (LS+ and GND) and was reading 3mVAC. Is this noisy?
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you have procedure for setting output offset in first post
9mV is good as 0mV; in general, anything in range of +/-100mV in thermal equilibrium is considered normal for any amp
dissipation is Iq*Rails, so for 1A8*70V=126W
AC at output - while amp is in that state (all over the bench) no much use of measuring it at all
what is exact figure when amp is assembled fully - dunno, didn't felt any need to measure it - it was Dodo on any spk I connected it to
9mV is good as 0mV; in general, anything in range of +/-100mV in thermal equilibrium is considered normal for any amp
dissipation is Iq*Rails, so for 1A8*70V=126W
AC at output - while amp is in that state (all over the bench) no much use of measuring it at all
what is exact figure when amp is assembled fully - dunno, didn't felt any need to measure it - it was Dodo on any spk I connected it to
I stuffed a second board today and it did non catch fire or explode. If I can find some Speakon sockets I will give it a listen later tonight. I did mangle T7 a little when I put it in T6 by mistake, I hope it is ok. My de-soldering skills suck sometimes.
I will post how I get on with the naked XA252 if I give it a go😘
I will post how I get on with the naked XA252 if I give it a go😘
Very neat! I usually remove small transistors by putting a big glob of solder on the soldering gun and then going back and forth on the transistor's pads on the bottom of the board while pulling it gently with my fingers from the top. That way I can feel if it gets too hot. Usually it gets lukewarm if you do it right. Takes a few seconds.
yeah, that's a good practice ....... best done with wide chisel tip, heating all pins at once
Mighty Moi using Desoldering station in last couple of years ..... when I was a Kido, I needed to fart, to have that
Mighty Moi using Desoldering station in last couple of years ..... when I was a Kido, I needed to fart, to have that
Don’t tell anyone but I have been using lead free solder. Had to turn the iron up to 420c on the 3w resistors because of the heat vias. Normally at 320c and use flux on tricky bits.
lead-free solder is for eager Youngsters
Old Farts as me ........ naah
at least 3 different tips, 2 solder wire gauges, helper flux, head-lens ....... go figure
when I was a Youngster, I did 90% of my soldering by pure force of will, no equipment needed
Old Farts as me ........ naah
at least 3 different tips, 2 solder wire gauges, helper flux, head-lens ....... go figure
when I was a Youngster, I did 90% of my soldering by pure force of will, no equipment needed
My technique is using solder with lead and setting the iron to 666 degF. The solder melts beautifully and this technique prepares the amp for the inevitable playing of traditional heavy metal music when the build is complete!
I just checked - my XA252 boards are in transit. They left OPLDF in BAČ and are slowly making their journey to USA. I'm really looking forward to this build!!!
I just checked - my XA252 boards are in transit. They left OPLDF in BAČ and are slowly making their journey to USA. I'm really looking forward to this build!!!
Wow wow wow. It works, and sounds superb. As sweet as my AJ but has much better control of the bass and this is a low level test (daughter is asleep). It is running at about 50c. Thanks ZM, fantastic work.
I was worried about this one. It is the second amp I have made from a circuit diagram and also my second layout.
I was worried about this one. It is the second amp I have made from a circuit diagram and also my second layout.
Yes it is the mosfet only version. Had a listen to The Eagles, Fleetwood Mac, REM and Ali Farka Toure so far and they haven’t sounded so good. Only running the boards at 1A each, I am surprised a 250x100x38mm heatsink can keep up.
I will definitely crank it up. It is a real foot tapper. It is a step up from the AJ which I love and sounds amazing. I was not sure what to expect with such a small 2nd harmonic but you are right that as long as it is there. I used the 0R22 BFR thinking I might want to change it but at the moment I don’t.
way of preventing later troubles is to check CCS solo, mounting IC and associated parts first
then you can use even 9V battery and mA-meter, connecting that inside of series zener diodes
if it shows few mA and responds to trimpot, then one worry less
then you can use even 9V battery and mA-meter, connecting that inside of series zener diodes
if it shows few mA and responds to trimpot, then one worry less