, cool down or i´ll have this thread locked.
fumac!
In linear mode amps the wide freq. response is a "side-effect", not primary purpose. In some of them there is a filter to limit it, but 100...200 kHz is still harmless.
(For example now I make a linear mode current generator for 0...100 Hz signals, and despite of the low signal frequency every stage have to have n*100 kHz BW at least, because of the high precision requirements.)
In linear mode amps the wide freq. response is a "side-effect", not primary purpose. In some of them there is a filter to limit it, but 100...200 kHz is still harmless.
(For example now I make a linear mode current generator for 0...100 Hz signals, and despite of the low signal frequency every stage have to have n*100 kHz BW at least, because of the high precision requirements.)
The original topic was about fast switching stages. IMO they make sense for switching amps using delta sigma modulation.
PWM amps don't need them IMO.
A sufficient bandwidth (i.e. around 40 kHz) can be achieved with lower switching frequencies.
Flat group delay, low EMI, good carrier suppression, flat amplitude response, low THD, low IMD ....... can be achieved with low switching frequencies and well-known topologies.
Regards
Charles
PWM amps don't need them IMO.
A sufficient bandwidth (i.e. around 40 kHz) can be achieved with lower switching frequencies.
Flat group delay, low EMI, good carrier suppression, flat amplitude response, low THD, low IMD ....... can be achieved with low switching frequencies and well-known topologies.
Regards
Charles
tc4422 driver
Doing an engineering project using a board with a tc4422 on it, the driver started to smoke. Now it's dead. If you guys lived in the boondocks and wanted to find another tc4422, where would you look? I'm ready to resort to disassembling items in my house to get one out. This project is due Friday, so it's too late to try FedEx. Any suggestions? I appreciate any tips!
Doing an engineering project using a board with a tc4422 on it, the driver started to smoke. Now it's dead. If you guys lived in the boondocks and wanted to find another tc4422, where would you look? I'm ready to resort to disassembling items in my house to get one out. This project is due Friday, so it's too late to try FedEx. Any suggestions? I appreciate any tips!
hi eva, just reading about this post
http://www.diyaudio.com/forums/showthread.php?s=&threadid=79261&perpage=25&pagenumber=2
i agree with you about this :
as you say:
i think , you have very good knowledge from books,
so dont just stop at the talking at internet.
you need to make a so much low thd class-d amp to proof your Theory
from our mhz-power class-d module
we got a very low thd+n :
lowest is :0.0035% at 1k and 0.006% at 10k (1.5w 8ohm)
as you say, you need to make a class-d running at 100k or 150k then can get thd+n same like :
0.00035% at 1k and 0.0006% at 10k (8ohm) (10x better than ours )
so please show your project to us ,
if you can't make it ,
or just tell me who else can make a class-d like that.
Don't just stop at the books,
Don't just stop at talking at forums
Do a good job and show to us please.
as you day, i need to learn more, yes, i need to learn english and do more researching at class-d.
we never stop at the devolopments.
too busy this days, because our new baby was born 3days ago.
show you our new baby :
thanks
rg
fumac
http://www.diyaudio.com/forums/showthread.php?s=&threadid=79261&perpage=25&pagenumber=2
i agree with you about this :
Eva said:
as you say:
Eva said:
i think , you have very good knowledge from books,
so dont just stop at the talking at internet.
you need to make a so much low thd class-d amp to proof your Theory
from our mhz-power class-d module
we got a very low thd+n :
lowest is :0.0035% at 1k and 0.006% at 10k (1.5w 8ohm)
as you say, you need to make a class-d running at 100k or 150k then can get thd+n same like :
0.00035% at 1k and 0.0006% at 10k (8ohm) (10x better than ours )
so please show your project to us ,
if you can't make it ,
or just tell me who else can make a class-d like that.
Don't just stop at the books,
Don't just stop at talking at forums
Do a good job and show to us please.
as you day, i need to learn more, yes, i need to learn english and do more researching at class-d.
we never stop at the devolopments.
too busy this days, because our new baby was born 3days ago.
show you our new baby :
An externally hosted image should be here but it was not working when we last tested it.
thanks
rg
fumac
IVX said:BTW, at 1.5W your amp just working without dead time at all. Indeed learning is the best way for you, don't worry about english, I'm sure you can get right chinese books even.
ok
at 50w rms to 8ohm output :
mhzpower-4 : thd+n=0.009% at 1k, thd+n =0.01% at 6k (80k test bandwith)
then you can make a 100khz 10x better than us
so you need to proof: at 50w to 8ohm
thd+n=0.0009% at 1k and thd+n=0.001% at 6k (20k test bandwidth,
because you can't test 100k class-d at a 80k bandwidth at AP system ,you need a 22k filter pluse in,
same reason, you can't test true THD+N at 10k)
ok please show to us
rg
fumac
fumac!
Eva is right, but you have to understand that she was talking about THD before feedback. When you have feedback, THD goes lower, and because higher switching freq allows higher loop gain, THD returns to similar level as with lower switching freq.
So basically very high switching freq has not good, nor bad influence on THD.
P.S.: THD is not THD+n! You can't expect 0,00035 % THD+n at -20 dB, because noise of any device is already higher, but Eva was talking about only distortion! On the other hand: 0,00035 % THD at this level is achievable (however very difficult to measure).
Eva is right, but you have to understand that she was talking about THD before feedback. When you have feedback, THD goes lower, and because higher switching freq allows higher loop gain, THD returns to similar level as with lower switching freq.
So basically very high switching freq has not good, nor bad influence on THD.
P.S.: THD is not THD+n! You can't expect 0,00035 % THD+n at -20 dB, because noise of any device is already higher, but Eva was talking about only distortion! On the other hand: 0,00035 % THD at this level is achievable (however very difficult to measure).
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