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MHz class d amp

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#142
lumanauw said:

Hi, Fumac,
Do you use any notch filter or LPF for removing the carrier

spectrum before entering HP-3585A?
What kind of filter do you use? Active? Passive?
I know that Audio Precission (AP) have a special filter for measuring classD amps.
Click to expand...

EnvisionAudio said:


In Post #83, Fumac states that there is no filter. I find this

even more impressive.
Click to expand...

hi lumanauw
hi EnvisionAudio
thanks ur reply for me

yes
we did not use filter between amp and equipments.

we do some research in : why they need the filters.
because after the filter that inside class-d amp
there r a high level signal of pwm frequency there
most of low frequency class-d will reduce a signal at 0.8~3v(p_p) 300k~500k.
(we can call it pwm Residues signal, some one help me to name it in English)
if we test a 0.5V 1k signal ,
in fact will output a signal mixing 0.5V(1k)+0.8V(400k) ,
we cant hear the 400k signal, but the tester can.
and the pwm signal will harm to the input stage of tester.

ok , back to 1mhz, we just have a very low pwm Residues signal, 50mv (0.09v P_P at 1mhz),
so this is not so much harm to the input stage of the tester.

this is one of reasons that we goto 1mhz .

and another side :
the test bandwidth of HP-3585A is 20hz~42MHz , and the AP is about 0~350k, so the input stage is different.
so i needn't the filter when i use hp-3585

if i use the filter, the numbers will looks better than now .

my english is not good , if someone know what's the meaning of me , pls say it in right way

rg
fumac
 
#145
scintillaman said:
Fumac

I sent you a email for purchase instructions for a pair of your modules. I need information on how to make the purchase.

Thanks

Carlton
Click to expand...

hello Carlton
nice to meet u
i will post how to diy the mcd moduls to be a ampilifer.
is very easy to build.
because mcd is a full funtion module

but i'd like to post the test photo first.
if u like , u can post a new title : how to build a mhz class-d ampilifer,(or how to diy....)
then i will post it at new topic.

thanks
btw: i had not recieve email from u , 🙁

rg
fumac
 
#146
hi lumanauw
hi EnvisionAudio

another thinking about the filter between the ap and class-d amp

pwm Residues signal (PRS) will Interference the input stage of the ap system

another think is that : PRS also will Interference the input stage of the class-d amp.

the PRS from the class-d amp output ,
then through the speaker line output to outside.
then go to the input stage of the class-d amp or other parts,(EMI)

so the high PSR output is not "not need to care " .

how can we do with it
1. low PSR output (raise up the frequency)
2. add a input filter before the input stage(same like AP )

1mhz is far far away from the audio range frequency,
so can be very easy to make it lower with a simple filter,
but low frequency also need to care about the frequency respond
so, hard to balance it .

this is another reason to make it running at 1mhz .

rg
fumac
 
#148
scintillaman said:
Fumac

I don't know why you did not receive my followup email. You initially responded to my inquiry and gave me euro purchase price. Maybe 1 ohm operation will refresh your memory.

Carlton
Click to expand...


hello carlton
this days is Chinese Winter Solstice days
in south china, it is a very important days ,
so i need to spend my time with my family.
sorry for delay.

your need is stranger to us,
we just sale the mcd-255 as a 250w modules ,
and the module have a huge peak output current(26A peak).
so it can drive 1ohm load, but not good at 1ohm.

but you want to bridge two module then to drive 1ohm load,
this will be danger.

we can calculate :
1: use one module to driver 1ohm.
power supply is +/- 45V, if con net to 1ohm load,
then the max current is 45A(peak), this is out of our design.

at this time , the output power is 1kw to 1ohm, far away than our 250wrms output ,
the bridge will be break ed and the speaker protection relay also not enough.
and, and the Efficiency will be very low, then the modules go to very hot , then break .
so i think , mcd-250 is not good at your project.

2. bridge 2 mcd-255 to driver 1ohm , will be worst.
this will be 4kw rms output at +/-45V supply.
and more than 90A current that u need.

3. we can calculate from another way.
how many power output when mcd-255 con net to low load.
2ohm : +/-45V to 2ohm is 22.5A peak,
so if the power supply is good enough ,
then can output 500w rms (just by calculate, not the real),
but when amp is loading low driver , the thd will be higher,
and max power output is calculate at thd=10%.
the Efficiency will be lower,
so the max output power will be lower than 500w.
we have test 1.5ohm load , can output 400wrms.
but go to hot faster, need extention heat sink and fan.


4. another choice:
if your 1ohm load is Parallel by 4x4ohm,
that is very easy to do with it,
u can one power amp for one speaker,
this also can output 250wx4=1kw
will be safe and cool.

if you want to driver 1ohm load bass boost
then cant use our modules
u can buy class-d bass boost working at 50k~100k,
and output power to 1kw to 5kw (1ohm),
that is design for low load,
will be very good for your project

5. another link about loading 1ohm
http://www.diyaudio.com/forums/showthread.php?s=&threadid=114091

perhaps can help you .


I'm grade to answer u any questions ,
Even i cant sale anything to u .

i cant sale mcd-255 to u ,
because i want the mcd modules running at his best State,
safe , Health and good sound .

rg
fumac
 
#149
a picture of mcd-250
about the frequency respond

5hz~53kHz +0/-0.05db
 

Attachments

  • fr 20~53k -0.05db.jpg
    fr 20~53k -0.05db.jpg
    84.7 KB · Views: 466
#153
mcd-255 pins and funtions

Pin Function
J1-J3: AC Power input:
J1,J2: AC IN connect to the power transformer
J3: AC COM

J9-J11: DC power input or extension caps connector
J9: VSS , - Rail of DC power
J10: GND, GND of DC power
J11: VDD, +Rail of DC power

J7,J8: Speaker output
J7: speaker +
J8: speaker -

N103 : Extension 15V DC
J5: 0V Don't connect to GND
J6: +15V DC max cap 1000uF

N104: enable pin
J18: EN
open : power on
close to J19 😛ower down
J19: GND

N105:Balance input pin (use bb2134)
pin1: Pre-amp input +
pin2: Pre-amp input -
pin3: Pre-amp input GND


N106: volume control pin
pin1: Pre-amp output , to input pin of pot
pin2: Power-amp input , to middle pin of pot
pin3: Power-amp input GND, to GND pin of pot
 

Attachments

  • mcd-6 pins.jpg
    mcd-6 pins.jpg
    68.5 KB · Views: 721
#154
fumac said:




hi lumanauw
hi EnvisionAudio
thanks ur reply for me

yes
we did not use filter between amp and equipments.

we do some research in : why they need the filters.
because after the filter that inside class-d amp
there r a high level signal of pwm frequency there
most of low frequency class-d will reduce a signal at 0.8~3v(p_p) 300k~500k.
(we can call it pwm Residues signal, some one help me to name it in English)
if we test a 0.5V 1k signal ,
in fact will output a signal mixing 0.5V(1k)+0.8V(400k) ,
we cant hear the 400k signal, but the tester can.
and the pwm signal will harm to the input stage of tester.

ok , back to 1mhz, we just have a very low pwm Residues signal, 50mv (0.09v P_P at 1mhz),
so this is not so much harm to the input stage of the tester.

this is one of reasons that we goto 1mhz .

and another side :
the test bandwidth of HP-3585A is 20hz~42MHz , and the AP is about 0~350k, so the input stage is different.
so i needn't the filter when i use hp-3585

if i use the filter, the numbers will looks better than now .

my english is not good , if someone know what's the meaning of me , pls say it in right way

rg
fumac
Click to expand...

Your English is much better than my Mandarin! I understand everything fine.
 
#159
we will do a show in china,guangzhou

MHzpower 400w class D amplifiers, 66 hours non stop HI-FI show(all day and all night)

From the 27th until the 30th of November 2008, in the Shamain hotel, in Shamain, Gaungzhou, China,
Huygens Audio will be presenting their brand new MHzpower 400W Class D power amplifiers.
We welcome you to the greatest Hi-Fi show, which will run non stop over the three days,
an event not to be missed and the first public showing of our new MHz class D Technology.

An externally hosted image should be here but it was not working when we last tested it.


An externally hosted image should be here but it was not working when we last tested it.


wellcom every body 🙂

rg
fumac
 
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