| gogowatch |
I have built a power amp with UCD180 module end of 2006 and listen to it nearly everyday. I'm quite satisfied with it. Then I attempted to built a UCD amp from the Philips application notes by referring to the thread http://www.diyaudio.com/forums/show...threadid=85389. I built one channel UCD on a breadboard and seem to be working good. Then I make some PCBs and have built several modules. But unfortunately I got stability problem. I haven't found the reason why yet but I do believe the problem is with the inductor.
After reading a thread in Vendor Bazaar forum about an MHz Class-D power amp module, I decided to have a try a Class-D amp with higher switching frequency. The modules MCD-255 are not cheap at all although it is come from China.
As a DIYer, I'm quite confused that no instruction manual was enclosed in the package. I remembered that the designer had posted the connection diagram. So, I get the diagram there and start building the amp. I'm also frustrated that the some part of the circuit is sealed as shown in the attached pictures. Considering the condition of soldering, the module seems to be soldered by hand. The PCB has not been cleaned as well.
The documentation from the manufacturer is almost NONE, so I start this thread to share with other builders.
Following are my questions,
1. What is the input power voltage range? I got two 24V AC transformers currently for testing. Before any attempt to connect a speaker, I wanted to measure the switching residue at the output with a 100MHz scope first. But I failed. I can hear two relay clicks when it was powered up. I cannot measure any switching residue at the output. It seems the amp was not yet started up or the protection circuit was in action.
2. The module comes with a built-in pre-amp, which can be bypassed. So, what are the input impedances and the gains of the pre-amp and the power stage?
3. Is it appropriate to enclose the inductor with a shrink-wrap jacket? Will the inductor get hot during operation?
4. Is the input DC or AC Coupled?
Thanks in advance. |
|
|
| gogowatch |
| One more picture. |
|
|
| fumac |
hello gogowatch
happy new year
1.about the data sheet:
you are the very first user of mcd-255(ver 6)
and we are doing with the paper work.
so we promise that we will post the pdf at this two days.
sorry for the delay.
2.
the black one is the protection of mcd-modules.
and the res is the dead time turner,
we test every pcs of mcd modules before it go out to users.
and we will turn the dead time by hand for every pcs to make it run at his best .
sorry for the "not clean well ", i will check the product line to make it better.
thank you for your post
then i will answer your questions
rg
fumac |
|
|
| fumac |
question 1
1. What is the input power voltage range? I got two 24V AC transformers currently for testing. Before any attempt to connect a speaker, I wanted to measure the switching residue at the output with a 100MHz scope first. But I failed. I can hear two relay clicks when it was powered up. I cannot measure any switching residue at the output. It seems the amp was not yet started up or the protection circuit was in action.
------------------------------
mcd-255 need a +/-45V DC supply for 250w.
the max voltage is +/-49V dc (35V AC, will protection at about 50V),
but the input voltage of 230v(or 110v)sometimes will up to 110% or 120%.
so we need a voltage under 49v-6v=43VDC(30V AC)
===so 30-0-30v (AC) is a best choose.===
24V AC is too low, sometimes cant power up.
so this voltage is not the best choise of
so the best is raise the voltage.
but you can heard the "click" of relays , that meaning it is running.
i'm sure it is running.
because the speaker protection of mcd is checking the pwm signal ,
if working ok the relays will turn on. if not , the relays will turn off.
so if you heard one sound of "click", this is meaning : mcd is running .
mcd just output very low switching residue voltage(mV level),
not like others(V level).
so u need to turn your osc scope to lower range.
perhaps you can look at it .
also u cant just hearing the speaker to know about it is on/off.
because mcd output a very low noise.
rg
fumac |
|
|
| fumac |
the built-in pre-amp is working at +/-15v regulator.
Gain : 30.5db, (33.6x)
before pot (input stage): 6db(2x)
after pot(buffer): 9.5db(3x)
power stage :15db(5.6x)
if u input a 1v signal then you can get a 33.6v at the output pin.
so you can use most of music source .also low level output source.
input impedance :
pre-amp :15k (unbalance),30k (balanced)
buffer:18k
power stage: 6k
because mcd have a high input impedance,
so you can use a tube pre-amp to replace the pre-amp.
or even replace the buffer.
4. Is the input DC or AC Coupled?
pre-amp input is DC Coupled
pre-amp to buffer is DC Coupled too
buffer to power stage is AC Coupled (20uf cap)
|
|
|
| fumac |
question 3
3. Is it appropriate to enclose the inductor with a shrink-wrap jacket? Will the inductor get hot during operation?
because the good design of mcd-255, the inductor just get a mini hot during operation.
so we enclose the inductor with a shrink-wrap jacket,
this will make the value of inductor more Stability
enjoin your new amp
rg
fumac |
|
|
| fumac |
here is the minisystem of mcd-255
when you plug the power into it , it will run :) |
|
|
| gogowatch |
Thanks for your reply, Fumac.
I have just made one module start running. You guess what I've done wrong? .... I haven't supply the DC15V. I just thought the DC15V is used for the pre-amp circuit that I don't want to use at the moment. After I supplied the DC15V, I =got a single relay click, instead of two previously. When I power it down, I got another relay click. That's more reasonable. Does the module need high quality DC15V power supply?
I haven't got all the components to build a complete amp. So I did some measurements before I go ahead. Attached is switching residue with power stage input shorted to ground and no load connected at speaker output. Scales are 0.2us/div and 50mV/div. It shows a ptp 220mV residue and switching frequency ~900KHz. The trace shows some high order frequencies ripples. Is that normal?
Regards, |
|
|
| fumac |
| quote: | Originally posted by gogowatch
Thanks for your reply, Fumac.
I have just made one module start running. You guess what I've done wrong? .... I haven't supply the DC15V. I just thought the DC15V is used for the pre-amp circuit that I don't want to use at the moment. After I supplied the DC15V, I =got a single relay click, instead of two previously. When I power it down, I got another relay click. That's more reasonable. Does the module need high quality DC15V power supply?
I haven't got all the components to build a complete amp. So I did some measurements before I go ahead. Attached is switching residue with power stage input shorted to ground and no load connected at speaker output. Scales are 0.2us/div and 50mV/div. It shows a ptp 220mV residue and switching frequency ~900KHz. The trace shows some high order frequencies ripples. Is that normal?
Regards, |
cheers and happy new year
i like to hear about your mcd-255 is running :)
the 15V sub power is for control circle and low side driver
there are a 12v regulator inside mcd-255.
so not need to add a extension regulator for mcd-255
and the caps of the sub-power must be under 1000uf.
if large than it , it will be make err to the soft-star circle.
about the PWM frequency, the frequency is depend on the power rail ,if you use higher rail, (+/-43v), then you can get the higher pwm frequency, also when the mcd-255 warm up,the frequency will also goto 1mhz(+/-60K)
and about the 220mV residue , when the pwm frequency higher, the residue will be lower.
you can test about your another low frequency class-d amp, then you will find our residue is very very lower than others
another side, we can make the residueunder 10mV, but this will make the frequency respond jst up to 50kHz(-3db), but we have test about it , up to 150khz(-3db) is quite better than the 50k.
so take it easy :)
rg
fumac |
|
|
| gogowatch |
| One more trace. This one is from the power amp output pin without speaker loading with triangular signal at power stage input pins. Scales are 0.2ms and 10v/div. |
|
|
| soongsc |
| quote: | Originally posted by gogowatch
One more trace. This one is from the power amp output pin without speaker loading with triangular signal at power stage input pins. Scales are 0.2ms and 10v/div. |
10V/div=60V?
:eek: |
|
|
| gogowatch |
Soongsc,
Yes. It is 10v/div. So it is 60V ptp and it is just before clipping. The supply rails are +/-33V. Please note that I haven't attach any loading at the amp's output.
I'll measure it again after I build some dummy load.
Cheers, |
|
|
| soongsc |
| I think it would be interesting to see difference between a resistive load and a tweeter driver type load. |
|
|
| Eva |
| quote: | Originally posted by gogowatch
Thanks for your reply, Fumac.
I haven't got all the components to build a complete amp. So I did some measurements before I go ahead. Attached is switching residue with power stage input shorted to ground and no load connected at speaker output. Scales are 0.2us/div and 50mV/div. It shows a ptp 220mV residue and switching frequency ~900KHz. The trace shows some high order frequencies ripples. Is that normal?
Regards, |
The "high order" frequencies are plain EMI (electromagnetic interference) and are the result of bad engineering and poor PCB layout. They should not be there. This is particularly true if the amplifier was idle when you took this picture, because the RF "ringing" will become much worse under load when substantial current is being supplied to the speaker.
You can take a look at the carrier residuals of your original UcD modules (good engineering) and you will see a clear difference in waveform quality. A good class D module should not exhibit any RF ringing at the speaker output (or at any input/output connector) because wires are nice antennas.
This article is worth reading too, if you have not read it already:
http://www.audioholics.com/educatio...d-basics-page-2 |
|
|
| fumac |
| quote: | Originally posted by Eva
The "high order" frequencies are plain EMI (electromagnetic interference) and are the result of bad engineering and poor PCB layout. They should not be there. This is particularly true if the amplifier was idle when you took this picture, because the RF "ringing" will become much worse under load when substantial current is being supplied to the speaker.
You can take a look at the carrier residuals of your original UcD modules (good engineering) and you will see a clear difference in waveform quality. A good class D module should not exhibit any RF ringing at the speaker output (or at any input/output connector) because wires are nice antennas.
This article is worth reading too, if you have not read it already:
http://www.audioholics.com/educatio...d-basics-page-2 |
hi eva happy new year
yes your thinking is right,
but perhaps you just told others a part of truth
most of testing ringing is come from method of measurement
yes, most of diy project.
measurement technolege is very complex
i think the ringing is came from the GDN pin of probe too long
perhaps gogowatch can post a pic of the test probe
and i show you a picture
eva if you like , we can post a new topic :measurement of class-d amp.
perhaps can help other ture
rg
fumac |
|
|
| gogowatch |
Eva and Fumac,
Attached is the picture of the amp during my measurement. You can guess the state of the ground pin of the probe.
Cheers, |
|
|
| gogowatch |
| quote: | Originally posted by soongsc
I think it would be interesting to see difference between a resistive load and a tweeter driver type load. |
Soongsc,
I don't have standalone tweeter driver on hand. Is it useful to test driving an ordinary two ways speaker?
Cheers, |
|
|
| Eva |
A proper design does not ring, particularly not above 10Mhz because radiation becomes much easier. It may exhibit just one or two damped oscillation cycles, but never a dozen cycles with very slow decay. The net amount of EMI radiated is proportional to the number of cycles ;)
Of course, if some part of the circuit is ringing above 10Mhz, you will notice it with oscilloscope probes no matter where you connect them because part of this ringing will be common-mode (circuit ground will be no longer RF ground!!) and part of it will be just radiated and picked up by the probes.
The only remedy for this is to kill the ringing, which is achieved by removing as much parasitistic RLC systems as possible and ensuring that the rest of unavoidable RLC systems in the power path are reasonably damped. This is some kind of obscure RF engineering :D
BTW: Now you are free to continue telling everybody that my PCB layouts are bad, but then again, I get no ringing at the output, I "shape" my EMI to appear as clean pulses ;) |
|
|
| gogowatch |
Fumac,
Attached the image shows how I arrange the probe similar to the one when I did the residue measurement last time.
Cheers, |
|
|
| fumac |
| quote: | Originally posted by gogowatch
Fumac,
Attached the image shows how I arrange the probe similar to the one when I did the residue measurement last time.
Cheers, |
good job gogowatch
your installation design is quite good,
samll signal and large singal is Separated
and you use two transformer for two channel
this is quite good for low cross talk and power output
also you can add more caps , it will be very good for high dynamic
and can you talk about the sound feeling of it
perhaps many people like to know that
you are the only one have both mcd and ucd,
btw, the osc probe is alittle longer, show you a pic about a high frequency osc probe
a right Test Method will get the Accurate results
and can you tell me the length of your gan pin
rg
fumac |
|
|
| fumac |
| quote: | Originally posted by Eva
BTW: Now you are free to continue telling everybody that my PCB layouts are bad, but then again, I get no ringing at the output, I "shape" my EMI to appear as clean pulses ;) [/B] |
ohh , i know the reason about it ,
http://www.diyaudio.com/forums/show...25&pagenumber=4
i'm so sorry for that i have say : i dont like your design .
because i'm chinese and dont know my english words will hurt you, so sorry for that .
rg
fumac |
|
|
| Eva |
| Then I don't like your EMI ringing :D |
|
|
| gogowatch |
| quote: | Originally posted by fumac
...
and can you talk about the sound feeling of it
perhaps many people like to know that
...
and can you tell me the length of your gan pin
...
|
The input voltage for the MCD is bit under voltage. I've ordered a pair of transformer and should be get delivered in a couple of days. I'll do some A/B test with UCD then.
Attached is the probe I'm using. The ground pin is 15cm long. |
|
|
| Eva |
There is no excuse. Ringing is supposed to be damped in any commercial product.
On the other hand, since your probes look like 1x/10x switchable, and the RF bandwidth in 1x mode is severely compromised, you may want to repeat the measurement at 10x if it wasn't that way the first time. |
|
|
| gogowatch |
| 10x switch was selected when I posted the first measurement. |
|
|
| gogowatch |
Fumac,
I have rebuilt the amp replacing the 24VAC toroid by a 30VAC one. The amp using 24VAC toroid performs very well basically except some problem with the bass. When I played the bass loudly, it clipped. With the new 30VAC toroid, all the problems went away. Now my amp sounds well both in bass and in treble, with deep and wide soundstage and very precise positioning.
Thanks for your tips.
Cheers, |
|
|
| kittikun |
Hi gogowatch,
Do you add any external caps to the module? I have this module and having the same problem as yours.
Kittikun |
|
|
| gogowatch |
Hello kittikun,
I solved my problem simply by replacing the 24VAC transformer with a 30VAC one. I haven't added any external bypass caps. My speaker is a 8 ohm one.
Hope this helps.
Cheers, |
|
|
| kittikun |
Hi gogowatch,
My new 30-0-30 AC torroid is on their way to my home in a few days. I plan to put more caps for the supply but I'm not sure whether the different is well worth the effort.
I will try to change the torroid and see the result. The caps may be added later.
Thanks for your information.
Regards,
Kittikun |
|
|
| fumac |
| quote: | Originally posted by kittikun
Hi gogowatch,
My new 30-0-30 AC torroid is on their way to my home in a few days. I plan to put more caps for the supply but I'm not sure whether the different is well worth the effort.
I will try to change the torroid and see the result. The caps may be added later.
Thanks for your information.
Regards,
Kittikun |
hello kittikun
have you replace the torroid, and how about it :)
rg
fumac |
|
|
| kittikun |
Hi Fumac,
The previous torroid is 24-0-24 VAC 300VA and the mcd protection relay is cut the speaker off quite often. The new 30-0-30 VAC 500 VA is working nicely and put its quality into another level. Now the bass is tighter, powerful and accurate. The overall sound is more three dimensional with halographic imaging. The strength of mcd is the very smooth and refine mid and high extension. I like its simplicity for just a torriod and 2 modules to make it sings.
Regards,
Kittikun |
|
|
| fumac |
| quote: | Originally posted by kittikun
Hi Fumac,
The previous torroid is 24-0-24 VAC 300VA and the mcd protection relay is cut the speaker off quite often. The new 30-0-30 VAC 500 VA is working nicely and put its quality into another level. Now the bass is tighter, powerful and accurate. The overall sound is more three dimensional with halographic imaging. The strength of mcd is the very smooth and refine mid and high extension. I like its simplicity for just a torriod and 2 modules to make it sings.
Regards,
Kittikun |
good, i should like to heard that you like the sound from MCD
500VA for two module is good .
but the best is two transformer for two modules
at least 400VA for one channel.
we design the MCD is very easy to install,
enjoin your new amp :)
have you comparat to any other amps
what speakers that you are using
rg
fumac |
|
|
| fumac |
| quote: | Originally posted by gogowatch
Fumac,
I have rebuilt the amp replacing the 24VAC toroid by a 30VAC one. The amp using 24VAC toroid performs very well basically except some problem with the bass. When I played the bass loudly, it clipped. With the new 30VAC toroid, all the problems went away. Now my amp sounds well both in bass and in treble, with deep and wide soundstage and very precise positioning.
Thanks for your tips.
Cheers, |
welcome,
if you have other question, please ask
a good news, we have testing our SMPS power supply for AMP
400wrms, just testing , no other news
rg
fumac |
|
|
| etoastw |
I contacted Fumac at the start of September last year, and ended up buying two of these modules. I like the concept behind them (higher switching frequency), it was either these or UcD for me, and for no particular reason I thought I'd give these a go (Fumac seemed like a nice guy). Mine are hand-assembled by Fumac, so they look a bit different to the ones in the photos here.
Unfortunately, because I take so long to do anything, I didn't get them set up and working until last weekend. (Buying DIY stuff here in London has proven harder/more tedious than I thought it would be.)
I've got the modules in the simplest configuration (two channels, one transformer, no extra capacitors, 15V power pack) and I like the sound. I'm no expert though, I have no other amp (here in the UK) to compare it to, so I'm sort of going of the memory of the amps I've auditioned in shops and my old one back at home in Australia.
Basically I like the sound a lot. I haven't got it in a case or anything yet, and the layout is far from ideal, but I reckon it sounds great. The bass is nicely textured, and there is a lot of detail. I've got it hooked up to EPOS M12.2 speakers, and the combo seems to work well.
I would be interested to know how other people compare these modules to UcD modules, or to other amps (DIY or otherwise). Mainly just for personal interest, I won't be switching amps anytime soon :) |
|
|
| fumac |
| quote: | Originally posted by etoastw
I contacted Fumac at the start of September last year, and ended up buying two of these modules. I like the concept behind them (higher switching frequency), it was either these or UcD for me, and for no particular reason I thought I'd give these a go (Fumac seemed like a nice guy). Mine are hand-assembled by Fumac, so they look a bit different to the ones in the photos here.
Unfortunately, because I take so long to do anything, I didn't get them set up and working until last weekend. (Buying DIY stuff here in London has proven harder/more tedious than I thought it would be.)
I've got the modules in the simplest configuration (two channels, one transformer, no extra capacitors, 15V power pack) and I like the sound. I'm no expert though, I have no other amp (here in the UK) to compare it to, so I'm sort of going of the memory of the amps I've auditioned in shops and my old one back at home in Australia.
Basically I like the sound a lot. I haven't got it in a case or anything yet, and the layout is far from ideal, but I reckon it sounds great. The bass is nicely textured, and there is a lot of detail. I've got it hooked up to EPOS M12.2 speakers, and the combo seems to work well.
I would be interested to know how other people compare these modules to UcD modules, or to other amps (DIY or otherwise). Mainly just for personal interest, I won't be switching amps anytime soon :) |
hi too busy this days, so...
happy to know that you like the mcd sounds.
yes , you have the only special looking mcd-255, my bad hand make version.
but the sounds is no diffrent with the version now.
your are the first one that using mcd-255 (diyer).
thanks for your trust .
fumac |
|
|
| etoastw |
| It sounds great -- I've been running it for nearly a couple of weeks now. Now, if I wasn't so busy at work, I'd buy a case to put it in -- at the moment it's sitting on a wooden kitchen chopping board. |
|
|
| fumac |
| quote: | Originally posted by etoastw
It sounds great -- I've been running it for nearly a couple of weeks now. Now, if I wasn't so busy at work, I'd buy a case to put it in -- at the moment it's sitting on a wooden kitchen chopping board. |
dont use a wood board :)
this will make it hot .
please put it on a Metal board.
rg
fumac |
|
|
| kittikun |
Hi Fumac,
You have done a good job. My speaker is a Response 2.5 clone with only 86 dB sensitivity and it is hunger for power. I owned Both UcD400 and Zappulse 2.3SE for a few years and your mcd is running for 2 weeks. I think that it needs more burn-in time.
At this moment, I can say that it is on par with UcD400. But please be noted that UcD has more than double the power of mcd. When I need higher power, I still prefer UcD.
Regards,
Kittikun |
|
|
| fumac |
| quote: | Originally posted by kittikun
Hi Fumac,
You have done a good job. My speaker is a Response 2.5 clone with only 86 dB sensitivity and it is hunger for power. I owned Both UcD400 and Zappulse 2.3SE for a few years and your mcd is running for 2 weeks. I think that it needs more burn-in time.
At this moment, I can say that it is on par with UcD400. But please be noted that UcD has more than double the power of mcd. When I need higher power, I still prefer UcD.
Regards,
Kittikun |
yes , for low Sensitivity speaker , more high power is need, so you can try our new high power version of MCD(will be ready)
rg
fumac |
|
|
| etoastw |
| quote: | Originally posted by fumac
dont use a wood board :)
this will make it hot .
please put it on a Metal board.
rg
fumac |
Oh, I know -- don't worry :), it's not getting too hot (I've been checking) -- I can't run it at high volumes anyway. Those thick aluminium slabs that my modules are on seem to be fairly effective heatsinks. (for other people reading, my modules are slightly different to the standard ones).
And the case is arriving soon :) Then it'll be inside there (and I might post a couple of photos here).
Still sounding good; my next effort is to find a decent source. I might have to buy a decent(ish) USB soundcard or something. |
|
|
| fumac |
| quote: | Originally posted by etoastw
Oh, I know -- don't worry :), it's not getting too hot (I've been checking) -- I can't run it at high volumes anyway. Those thick aluminium slabs that my modules are on seem to be fairly effective heatsinks. (for other people reading, my modules are slightly different to the standard ones).
And the case is arriving soon :) Then it'll be inside there (and I might post a couple of photos here).
Still sounding good; my next effort is to find a decent source. I might have to buy a decent(ish) USB soundcard or something. |
good etoastw, show you a pic of the preamp on board
we are doing research at preamp,
found that the thd of ne5532 is better than the op2134,
just because i cant find the new ne5532 here,
so i cant replace the op2134 with ne5532,
(i cant use 2nd hand components at mcd modules)
you can try to do it , ne5532 is cheap :)
we will do other researching of preamp.
happy Chinese new year
rg
this picture is +/-15v reg, 1k load, 6v rms output. 3x gain. |
|
|
| Eva |
| TL082 is not designed to drive 1Kohm at 6V rms. Recommended load for this op-amp would be 5Kohm or higher. |
|
|
| fumac |
| quote: | Originally posted by Eva
TL082 is not designed to drive 1Kohm at 6V rms. Recommended load for this op-amp would be 5Kohm or higher. |
yes eva,
we just do the hard loading test of the opamp.
6vrms to 1k
this will let us know : tl082 is not good at this.
at the first test, we use a 600ohm loading, and the tl082 cant run :) so we change to 1k,
rg
fumac |
|
|
| alfsch |
fumac, you could try NJM4580
good opamp, like 5532 |
|
|
| fumac |
| quote: | Originally posted by alfsch
fumac, you could try NJM4580
good opamp, like 5532 |
thanks alfsch
i'm doing a research of 20 types opamp, to test the charater of opamps running at diffrent loading, voltage and others.
but this is a topic of a hifi Magazine, perhaps will post after the Magazine sale.
thanks for your Proposal, could you tell me a list of op that you want to know about ?
rg
fumac |
|
|
| alfsch |
opamps...hmmm
ne5532
mc33078
njm4580
op2134
op275
ad8620
ad8066
lm4562 |
|
|
| soongsc |
| Is an on-board switching power supply considered? |
|
|
| fumac |
| quote: | Originally posted by alfsch
opamps...hmmm
ne5532
mc33078
njm4580
op2134
op275
ad8620
ad8066
lm4562 |
alfsch
thank you
fumac |
|
|
| fumac |
| quote: | Originally posted by kittikun
Hi Fumac,
You have done a good job. My speaker is a Response 2.5 clone with only 86 dB sensitivity and it is hunger for power. I owned Both UcD400 and Zappulse 2.3SE for a few years and your mcd is running for 2 weeks. I think that it needs more burn-in time.
At this moment, I can say that it is on par with UcD400. But please be noted that UcD has more than double the power of mcd. When I need higher power, I still prefer UcD.
Regards,
Kittikun |
hi Kittikun
perhaps you can try our mcd-400
mcd-400 will be ready
here is the thd of mcd-400 by ap system |
|
|
| kittikun |
Hi Fumac,
How soon will your mcd-400 be ready?
Is there any sound characteristics different from mcd-255?
Kittikun |
|
|
| fumac |
| quote: | Originally posted by kittikun
Hi Fumac,
How soon will your mcd-400 be ready?
Is there any sound characteristics different from mcd-255?
Kittikun |
hi kittikun
1. more output power : 420w at 1%(thd)
2. separate preamp and power amp.(you can take out the sub board of preamp.)
3, the power supply will be better(-10db noise lower).
4.less thd (pls ready the picture, test BW=30k)
because we got a set of ap system, so we can make it better .
rg
fumac |
|
|
| kittikun |
Hi Famac,
The design looks very nice with very high specification. I like the wide bandwidth with very low distortions. The good thing is everything seems to be on board, including the thermal protection. I notice that this module can received only single end input. Can it accept balanced input?
Regards,
Kittikun |
|
|
| fumac |
| quote: | Originally posted by kittikun
Hi Famac,
The design looks very nice with very high specification. I like the wide bandwidth with very low distortions. The good thing is everything seems to be on board, including the thermal protection. I notice that this module can received only single end input. Can it accept balanced input?
Regards,
Kittikun |
the mhzpower module is just the power stage . not including the preamp. also not including the buffer amp.
why we need the balance input , because we need a very low noise floor,
but , we have very low noise floor now . you can get the noise floor from the fft of data sheet.
(we use a normal transformer to test our amp, no regulate power supply , no 20k filter between class-d and AP system,
most of other damp testing is powered by regulated power supply and including a 20k filter between damp and AP)
most of amp is unbalance inside the case. because we hard to control the volume and hard to balance the gain at full balanced path (diy ).
some oen not like op-preamp(me too), i don't like to use a very good preamp(tube or class-A design),then to a op-amp then to power stage.
so we can use this one as:
source----> volume control -->class-A preamp---> mhzpower.
there are no more un-need opamp inside.
if we use a opamp to make the balanced input(like mcd-255 and other class-d modules ), the signal path will be very loog:
source----> volume control -->class-A preamp---> unbalance to balance ---->balance input(op inside the class-d)---> class-d amp
so mhzpower is good to some one good at diy. because they need to design the power supply and preamp and volume control.
simple is the best
rg
fumac |
|
|
| PeterLeest |
Hi Fumac,
In the MCD250 spec sheet, there is a soft power switch; namely, ¡°N104 enable pin¡±; used to powering on/off the module.
My plan is to build an integrated amp with full remote control. My remote control kit has a power on/off relay and it is controlled by the remote controller.
Instead of using the soft switch, can I use the relay to do a hard turn on (and off) of the amp? ie., leave J18/J19 open and supply power to the toroidal transformer. |
|
|
| fumac |
| quote: | Originally posted by PeterLeest
Hi Fumac,
In the MCD250 spec sheet, there is a soft power switch; namely, ¡°N104 enable pin¡±; used to powering on/off the module.
My plan is to build an integrated amp with full remote control. My remote control kit has a power on/off relay and it is controlled by the remote controller.
Instead of using the soft switch, can I use the relay to do a hard turn on (and off) of the amp? ie., leave J18/J19 open and supply power to the toroidal transformer. |
nice to heard about you are doing your project.
about the n104, this is a control pin for power down the power stage of MCD, if you have a remote control for the on/off, you can let the n104 keep opening, soft star inside MCD is funtionabel.
will have no pop noise when you turn on the power.
can you pose your pictures here ?
i like to take a look at your works
and how about the sound
rg
fumac |
|
|
| momoto |
Hi Fumac,
:D :smash:
me is atmel wong
:D :D :D |
|
|
| fumac |
| quote: | Originally posted by momoto
Hi Fumac,
:D :smash:
me is atmel wong
:D :D :D |
hello wong ,
nice to meet you here
"me is ...." saying is wrong English
you should say : i'm ....
but take it easy ,
most of the guy here are Friendly,
i'm not good at English too,
but they never laugh at my words
after you read more English here ,
you will be better
rg
fumac |
|
|
| momoto |
| :bawling: :bawling: :bawling: |
|
|
| langtuhanoi |
Hi Fumac,
MHZ-Power 4 is newest than MCD-255, ins't it?
It is very small module but powerful, I thing
Question:
2 MHZ-Power 4 and 2 transformer can make amplifier?, it have not a preamp or others module? |
|
|
| fumac |
| quote: | Originally posted by langtuhanoi
Hi Fumac,
MHZ-Power 4 is newest than MCD-255, ins't it?
It is very small module but powerful, I thing
Question:
2 MHZ-Power 4 and 2 transformer can make amplifier?, it have not a preamp or others module? |
hi ,
mhzpower modules is just a power-stage of a full amp
it is diffrent with mcd module
you need to add the power supply , caps and pre amp, and others to make a full funtion power amp
so it is not good at simple installation, most of it is for oem market, or some one good at eletronice technology.
MCD modules is very simple for diy. not need so much tech to build it up and get good sound.
fumac |
|
|
|
