Mm. So, universal solution to add phantom to almost every pre.
The story before the pictures not necessary to read, I marked it ----- -----
----- -----
Cool. Mentioned I hate DC/DC converters. Most of them.
Some time ago, came my friend with horribly racked V672.
The prob was contacts in gain switch and cracky pot, fixed'em and almost forgot, however, it probably was the start for idea.
Now, try to follow me. (He!)
Poor-thing's +24V power supply was done on 2x12V, 0.5A chinese trafo, 1000Uf 25V cap after rectifier and 7824.
No ceramic bypass even. All breadboarded. Quiet recognizable hands which should be cut out on guillotine one day, he!
Audio is quite a religion, so, let's give it some respect.
Than, saw the thing I really became crazy. There was small 15->12+12 dc/dc converter hooked to top of +24V to get total 48V phantom ref to earth.
With small ceramic 0.1uf from "phantom" point to gnd.
Besides the work inside the unit was real crap, the idea of criminal monster gave some lulz to old Addams like me.
The choose of converter was absolutely wrong, the person probably looked the easy way to get money for drugs or cheap booze,
and the noise at +48 was about 20 mV measured with tester in AC mode.
Huh! Guys, again, if you read this: don't do it _this_ way, have a respect to audio! However, try to read it till the end.
Ok, happens; I wished all the best to both-wrong-left-handed person who racked in hurry V672 and stopped to think about this...
Next, I became crazy on person which asked me if I use DC/DC converters in my units.
Well, for talkback combiner, it is OK to have less than 1mV AC of noise worst case, measured 10hZ-140kHz at power supply rails,
when inserting a weighting filter bla bla it becomes acceptable. The load is low (some milliamp's); so, this noise can be filtered.
For Microrack, the situ is different, say, 15W DC/DC converters aren't quiet in price acceptable range.
To express myself right, high quality DC/DC converters costs way more than we can afford.
I had some experience with 5->+/-15V 5W converters and have to say, finding converter with less than 1mV noise
at nominal load is not easy. I mean 1mV noise when I see it without weighting filters on analyser.
So, the prob of dc/dc converters is: cheap are wrong designed, work at 60 or 100k frequency, and NO GOOD for audio. Not kosher.
Well. 2 weeks later, one guy asked me if I can make universal phantom add-on which will work with
input voltage from +10 to +36V and bring 50-100 ma of clean phantom power at its output.
I reminded the DC/DC discussion thread, of course, you will find some lulz like "simple switcher" for audio use, he!,
http://www.groupdiy.com/index.php?topic=46702
AND after 3-4 hours the PCB design was ready. Not my first experience with PWM PS, so, gone smooth.
The last one successful PWM power supply experiment BTW was conversion of microamperes/kilovolts to volts/milliamperes,
to charge 24V accumulator from piezo-elements installed on road, for one really funny local startup company.
----- -----
OK...received the parts today, stuffed, and after some hours of testing....me happy!
UniPhan is: step-up converter, done audio kosher, (good as krishnait's food too), works at 300...400Khz,
has short circuit / overvoltage protection, stable, effective.
it requires: starground point, +10....36V input, and it's output is clean 48V at any load in 0...100 mA range.
Budget? For me it costed PCB proto and parts. In hundreds, should cost about
$25-30 in x100...200 batch production, if assembled in China, parts + labor only.
Proofed a claim about good DC/DC is not cheap and SHOULD be home brewed.
Well, let's see how good is it.
To be clear, if I mean noise in mV AC, next related to 10Hz-100kHz AUDIO range.
For comparison, normal console's supply gives a noise at 48V rail about 0.5...1 mv.
Inside pedigree pre, maybe it is possible to find shunt phantom regulator with less tha 0.2mV noise...
Well. Here is the baby. Say "Hello, Uniphan!"
No load
Test conitions: 15V input, 1k load (50 ma at 48V):
100mA load:
Ah yes, to compare. We did a project with one company for CO2 laser power measurement
with Japanese made 5->2x15V/200ma converters. I had some in my closet and took one to workbench.
Today they cost about $25 per converter in hundereds.
The story before the pictures not necessary to read, I marked it ----- -----
----- -----
Cool. Mentioned I hate DC/DC converters. Most of them.
Some time ago, came my friend with horribly racked V672.
The prob was contacts in gain switch and cracky pot, fixed'em and almost forgot, however, it probably was the start for idea.
Now, try to follow me. (He!)
Poor-thing's +24V power supply was done on 2x12V, 0.5A chinese trafo, 1000Uf 25V cap after rectifier and 7824.
No ceramic bypass even. All breadboarded. Quiet recognizable hands which should be cut out on guillotine one day, he!
Audio is quite a religion, so, let's give it some respect.
Than, saw the thing I really became crazy. There was small 15->12+12 dc/dc converter hooked to top of +24V to get total 48V phantom ref to earth.
With small ceramic 0.1uf from "phantom" point to gnd.
Besides the work inside the unit was real crap, the idea of criminal monster gave some lulz to old Addams like me.
The choose of converter was absolutely wrong, the person probably looked the easy way to get money for drugs or cheap booze,
and the noise at +48 was about 20 mV measured with tester in AC mode.
Huh! Guys, again, if you read this: don't do it _this_ way, have a respect to audio! However, try to read it till the end.
Ok, happens; I wished all the best to both-wrong-left-handed person who racked in hurry V672 and stopped to think about this...
Next, I became crazy on person which asked me if I use DC/DC converters in my units.
Well, for talkback combiner, it is OK to have less than 1mV AC of noise worst case, measured 10hZ-140kHz at power supply rails,
when inserting a weighting filter bla bla it becomes acceptable. The load is low (some milliamp's); so, this noise can be filtered.
For Microrack, the situ is different, say, 15W DC/DC converters aren't quiet in price acceptable range.
To express myself right, high quality DC/DC converters costs way more than we can afford.
I had some experience with 5->+/-15V 5W converters and have to say, finding converter with less than 1mV noise
at nominal load is not easy. I mean 1mV noise when I see it without weighting filters on analyser.
So, the prob of dc/dc converters is: cheap are wrong designed, work at 60 or 100k frequency, and NO GOOD for audio. Not kosher.
Well. 2 weeks later, one guy asked me if I can make universal phantom add-on which will work with
input voltage from +10 to +36V and bring 50-100 ma of clean phantom power at its output.
I reminded the DC/DC discussion thread, of course, you will find some lulz like "simple switcher" for audio use, he!,
http://www.groupdiy.com/index.php?topic=46702
AND after 3-4 hours the PCB design was ready. Not my first experience with PWM PS, so, gone smooth.
The last one successful PWM power supply experiment BTW was conversion of microamperes/kilovolts to volts/milliamperes,
to charge 24V accumulator from piezo-elements installed on road, for one really funny local startup company.
----- -----
OK...received the parts today, stuffed, and after some hours of testing....me happy!
UniPhan is: step-up converter, done audio kosher, (good as krishnait's food too), works at 300...400Khz,
has short circuit / overvoltage protection, stable, effective.
it requires: starground point, +10....36V input, and it's output is clean 48V at any load in 0...100 mA range.
Budget? For me it costed PCB proto and parts. In hundreds, should cost about
$25-30 in x100...200 batch production, if assembled in China, parts + labor only.
Proofed a claim about good DC/DC is not cheap and SHOULD be home brewed.
Well, let's see how good is it.
To be clear, if I mean noise in mV AC, next related to 10Hz-100kHz AUDIO range.
For comparison, normal console's supply gives a noise at 48V rail about 0.5...1 mv.
Inside pedigree pre, maybe it is possible to find shunt phantom regulator with less tha 0.2mV noise...
Well. Here is the baby. Say "Hello, Uniphan!"
No load
Test conitions: 15V input, 1k load (50 ma at 48V):
100mA load:
Ah yes, to compare. We did a project with one company for CO2 laser power measurement
with Japanese made 5->2x15V/200ma converters. I had some in my closet and took one to workbench.
Today they cost about $25 per converter in hundereds.