Zen Mod said:
Hi Choky,
Added 270g more into total 820g.
Density is quite high, but no distinguishable difference in the result.
Okay, I changed the input coupling cap of 47uF//1uF film to
10uF//1uF film. This was to try a high pass filtration. I didn't
calculate the frequency, tho . . .
Yep! finally, I'm on the spot.
The bass is tight and has very good pitch definition.
No mix of kick drum and bass guitar . . .
Some ocational weak boom is no more concern.
Excellent as music's tonal foundation at the right quantity.
Thanks for your helpful tips . . .
Two weeks later I'm going to invite a couple of critics, and will see . . .
Babowana said:
..............
Thanks for your helpful tips . . .
Two weeks later I'm going to invite a couple of critics, and will see . . .
you're my man,no need for thankssssssssssssss
please-be patient,I'm pretty in mess this last few weeks,so I just couldn't maked to post office .......regarding fishiefishie pcbs.......
Output Offset Voltage above the Ground
I tried to adjust the offset voltage to about 0V when the heat sinks are heated up enough, i.e. when the temperature change in heat sinks stops (saturated) and stays around zero.
By the way, since I am using unmatched complementary pairs of IRFP9240 and IRFP250N having quite different transconductance characters at room temperature, I read high output offset voltage when I just turn on the power. And, along the time length, I observe that the offset voltage reduces little by little to the final value I adjusted. It takes time. As an example, my measurement of the offset voltage change in the condition of 23 deg C room temperature shows the following figures:
Power on and
2 min later: 200mV
10 min later: 150mV
20 min later: 100mV
35 min later: 50mV
1 hour later: 5mV
3 hours later: -20mV
And, the offset continuously drifts inbetween -20 and -30mV
Both amps (two mono blocks) behave similar.
Therefore, I could say that it takes about half an hour for the amps to reach their normal operating condition within +/-50mV output offset range.
Not bad, isn’t it . . . ?
I tried to adjust the offset voltage to about 0V when the heat sinks are heated up enough, i.e. when the temperature change in heat sinks stops (saturated) and stays around zero.
By the way, since I am using unmatched complementary pairs of IRFP9240 and IRFP250N having quite different transconductance characters at room temperature, I read high output offset voltage when I just turn on the power. And, along the time length, I observe that the offset voltage reduces little by little to the final value I adjusted. It takes time. As an example, my measurement of the offset voltage change in the condition of 23 deg C room temperature shows the following figures:
Power on and
2 min later: 200mV
10 min later: 150mV
20 min later: 100mV
35 min later: 50mV
1 hour later: 5mV
3 hours later: -20mV
And, the offset continuously drifts inbetween -20 and -30mV
Both amps (two mono blocks) behave similar.
Therefore, I could say that it takes about half an hour for the amps to reach their normal operating condition within +/-50mV output offset range.
Not bad, isn’t it . . . ?
Take a look at this thread, I guess NP was in the breadcrumb mood
http://www.diyaudio.com/forums/showthread.php?s=&threadid=81350
Steen
steenoe said:Take a look at this thread, I guess NP was in the breadcrumb mood
http://www.diyaudio.com/forums/showthread.php?s=&threadid=81350
Steen
who's NP?
oh-ya mean Papa?
hehe
yes-I saw this
last night,fiddling with drawing of Babelfish X..........
steenoe said:Cant wait to see the result
Steen
ya already saw schmtc......but-counting on my superslow realization in last few yrs
....................I hope that I'll solve soon at least breadboard version.....
edit-
seriously,with Papa around to tease and use a stick in teaching purpose,some things are easy almost as Lego.....even without simulators.......
I just have no time for them (simulators) even if my install folders is full of them........
but-as I say- we don't really need sims......
Zen Mod said:
I have long filled up my memory box with many different sorts of sh@ts.
I guess that I’m not only one, though . . .
I get blinking lights and b- b- sound alarming narrowed empty space.
It is not strange that valuable info bypassing away from me.
I have to clean up the sh@ts off the box . . . when I still can do it . . .
Babowana said:
I have long filled up my memory box with many different sorts of sh@ts.
I guess that I’m not only one, though . . .
I get blinking lights and b- b- sound alarming narrowed empty space.
It is not strange that valuable info bypassing away from me.
I have to clean up the sh@ts off the box . . . when I still can do it . . .
your haiku is so bloody Engrish
check mail
Babowana said:
Small details in input coupling caps
As I informed earlier in this thread, I had some problem with J-low speakers in lower bass region with booming phenomena. I could cure this quite much, after having introduced air vents and filling stuff (polyester fiber) into the closed top and bottom corner spaces (dead spaces) of J-low.
It was, however, not good enough to avoid all booming when I was driving them with ZV5. Therefore, as an experimental purpose, I tried various input coupling caps of ZV5, which were acting in a way as high pass filters. I built the original ZV5 with the input coupling caps of 47uF electrolytic by-passed with 1uF film cap. But, I tried to change their values.
Results were as follows:
- 47uF elec.cap + 1uF film – Booming at rock bottom edges as if there to be a deficient damping factor
- 1uF film cap only – Dry bass
- 10uF elec.cap + 1uF film – Right pitch definition of bass, and weight
As a conclusion, the input coupling caps of total 11uF was working on the spot I wanted to have!
For example, I tried listening test of bass with various music CDs, particularly the album, “Blue Light Till Dawn” of Cassandra Wilson. Track 3: Tell Me You’ll Wait for Me,
Cassandra Wilson, Vocal
Kenny Davis, Bass
Kevin, Johnson, Snare
The fingering of the bass strings and the pitch definition were wonderful. In the middle of the trek, another bowing-bass joined the fingering-counter part . . . again, just perfect!
Now . . . I’m really wondering why the booming is no more concern with the 11uF input coupling caps changed from the 48uF . . . ? On the first approximation, I calculate that the cut off frequency of the high pass filter is merely at 1.3Hz with the 11uF caps, compared to 0.3Hz with the 48uF caps.
I could do is just a guess . . .
A peak power resonance in the network consisting of the output impedance of ZV5 and J-low speaker coil, and their low Q (“quality”) might have been happening at the rock bottom frequency when I had the 48uF input coupling caps. Meanwhile, the resonance peak power might have been lowered by the replaced 11uF caps . . . ???
Am I guessing too far . . . ?
Any different view why . . . ?
I lost direction . . .
I would much appreciate your guidance.
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Babowana said:
yup-you guessing too far.......just enjoy in result.....
mebbe combination of 47uF and bypass cap is bummy
mebbe just 47uF is culprit....
until you try another type of 47 cap,you can't know....
anyway-if you are in ballpark of 1Hz with 11uF - who cares?
put 2uF2 or 3uF3 there and hear increased speed
Zen Mod said:why?
you have calculator implemented in your 'scope?
Hehe . . .
My calculator has Papa's country brand made in Lumanauw's country. The screen shows even sine waves . . . I never use difficult functions, except the buttons of 1, 2, 3, 4, 5, 6, 7, 8, 9, 0, x, /, +, - and ENTER, though . . .
The calculator suffers from poor operator . . .
Hehehe . . .
Hehehehehehehehehe . . .
Choky,
With 11uF input coupling caps, 'scope measurement of ZV5 having voltage gain of 8 shows the 10Hz sine wave of about 6.8Vpp to the 1Vpp input. This means that 10Hz is still above the low critical frequency (-3dB at 5.6Vpp). Unfortunately, my signal generator can't go lower than 10Hz.
Meanwhile, the critical fL I calculated besed on the 1st approximation with Papa's home brand calculator was 1.3Hz. Therefore, the actual critial fL must be inbetween 1,3-10Hz. This means if I have 48uF coupling caps, the fCL must be further lower.
Then, why I hear the difference (post#93) . . . ?
My ears are fooling me . . . ?
A . . . yo . . .
With 11uF input coupling caps, 'scope measurement of ZV5 having voltage gain of 8 shows the 10Hz sine wave of about 6.8Vpp to the 1Vpp input. This means that 10Hz is still above the low critical frequency (-3dB at 5.6Vpp). Unfortunately, my signal generator can't go lower than 10Hz.
Meanwhile, the critical fL I calculated besed on the 1st approximation with Papa's home brand calculator was 1.3Hz. Therefore, the actual critial fL must be inbetween 1,3-10Hz. This means if I have 48uF coupling caps, the fCL must be further lower.
Then, why I hear the difference (post#93) . . . ?
My ears are fooling me . . . ?
A . . . yo . . .
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