MHz Class-D MCD-255 building question

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fumac said:

...
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.
 

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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.
 
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 said:
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
 
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
 
kittikun said:
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
 
gogowatch said:
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
 
I've got two of these modules as well

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 :)
 
Re: I've got two of these modules as well

etoastw said:
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
 
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
 
kittikun said:
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
 
fumac said:


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.
 
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