tiki said:Hi,
I know, it's not my competence, in my humble opinion it would be better to avoid mixing the themes between the threads. I would kindly ask you to discuss these supply problems in the appropriate thread. It will be easier to find any special information later, not only for me.
Thank you very much indeed!
For minimum capacitor requirements see Bruno's post. I for myself do not see any disadvantage for too big rail capacitors, except overkill and inrush current without a softstart circuit.
Best regards, Timo
Hi,
Timo is referring to this thread:
http://www.diyaudio.com/forums/showthread.php?s=&threadid=44515
Indeed it is a good idea to summarize supply discussions in that low volume thread, as the main UcD threads have become near-impossible to browse (about 95 pages for the UcD180 thread!), and the "search this thread" function is not very powerful.
I will quote Bruno's post on capacitor sizing on that thread.
I finally finished my amp, well almost, 99%. Check it out and give me plenty of compliments 😀 .
Not sure what I'm doing with the standby switch, that's those rolled up yellow wires tucked in the back. It took me over half a day just to do back panel! I also reduced the caps to 20000uF per rail.
Not sure what I'm doing with the standby switch, that's those rolled up yellow wires tucked in the back. It took me over half a day just to do back panel! I also reduced the caps to 20000uF per rail.
Very nice!!
Those UcD 400 will NEVER run hot with those heatsinks!
A little tip to everybody with UcD modules:
If you have two modules in the same box, and especially if they are placed close to each other, it is a good idea to place a 47nF between the two hot speakerterminals (as close to the modules as possible).
'
This is a trick used to syncronize two modules when used bridged, but it also works on two in a stereo amp. The benefit is that the switching freq, when they are in sync. will not make disturbances in the other module...
Try it and tell the results😉
Koldby
Those UcD 400 will NEVER run hot with those heatsinks!
A little tip to everybody with UcD modules:
If you have two modules in the same box, and especially if they are placed close to each other, it is a good idea to place a 47nF between the two hot speakerterminals (as close to the modules as possible).
'
This is a trick used to syncronize two modules when used bridged, but it also works on two in a stereo amp. The benefit is that the switching freq, when they are in sync. will not make disturbances in the other module...
Try it and tell the results😉
Koldby
UCD 400 availability
Hi all,
Haven't got enough time to seek info in there, but has anyone a hint about UCD400 availability ?
Beautiful work Chris ! That's what I like to see 🙂
Thanks,
Thierry
Hi all,
Haven't got enough time to seek info in there, but has anyone a hint about UCD400 availability ?
Beautiful work Chris ! That's what I like to see 🙂
Thanks,
Thierry
But the switching frequency does vary over the full cycle of the waveform, so you can't sync the two modules (unlike a clocked class-D design where sync-ing the two channels together stops any possibility of heterodyne whistles.)
If you are running two modules in a bridged configuration then I guess you might be able to sync them, as both modules are amplifying the same input waveform.
If you are running two modules in a bridged configuration then I guess you might be able to sync them, as both modules are amplifying the same input waveform.
Ouroboros
I know this should be so, but neverthe less it works with two modules, mounted closely, and has a beneficial impact on the sound!
There is no doubt that they are in sync with no signal and perhaps they stay in sync. a lot of the time and only when hard driven and with very differnt signals in the two channels , they loose sync. ??
Anyway, it works soundwise, but maybe only when they are close together, it is audible?
Koldby
I know this should be so, but neverthe less it works with two modules, mounted closely, and has a beneficial impact on the sound!
There is no doubt that they are in sync with no signal and perhaps they stay in sync. a lot of the time and only when hard driven and with very differnt signals in the two channels , they loose sync. ??
Anyway, it works soundwise, but maybe only when they are close together, it is audible?
Koldby
koldby said:
??? It seems to me that if you sync the switchings the two outputs should be identical so you should loose stereo, is'nt it so?
uh huh, you may not lose it entirely, but I think it would have to hurt channel seperation. What of distortion? These are self oscillating for a reason, wouldnt' that trick just kill the good specs these modules get?
chrisb03 said:
Splendid really! Maybe you could add a page with a bill of materials and details of fabrication, looks like a reference implementation to me! 😀
Golgoth said:
I'm forced to agree! Layout is superb, the supplies all out... I'm turning green.
Michel
No the sync. is only reffering to the switching freq. and not to the modulation (the audio signal) . The 47nF is too small to have an impact on the audio signal.
Koldby
No the sync. is only reffering to the switching freq. and not to the modulation (the audio signal) . The 47nF is too small to have an impact on the audio signal.
Koldby
koldby said:
The switching freq and the modulation are the same in this case: the modulator in the UcD is basically a comparator which compares the input signal to a scaled down version of the output signal.
IMHO the two channels when synced via the 47nF should play the same sound, even with zero signal on one of the two inputs (XLR disconnected). Keep us updated 🙂
I agree, and that's the whole point to that cap, in bridge mode, so that both modules do play the same sound, by synching the modulation of them, while the frequency itself can be ignored.
If you reaaaally want the frequencies to be the same I believe you can mix a clock signal with the input (high frequency triangle) and that will force the frequencies to be matched without killing channel seperation. I've no idea how that would sound or what it would do for noise etc. Likely to be far more trouble than it's worth.
If you reaaaally want the frequencies to be the same I believe you can mix a clock signal with the input (high frequency triangle) and that will force the frequencies to be matched without killing channel seperation. I've no idea how that would sound or what it would do for noise etc. Likely to be far more trouble than it's worth.
It has no sense to try to synchronize the two modules. In a way it will worsen it, because you are trying to synchronizing two modules who has two different signals. It has only sense if the two modules have the same signal as in a bridge mode.
It is possible to use a clocksignal at the input of the UcD modules, the oscillator will start directly to synchronize on this signal. The only reason to do this is to avoid mixing product or tones. But the HF emission of the UcD modules are low enough, so you normally wil not have this kind of problems.
And using a synchronize module will decrease the loopgain, so this will in a way WORSEN the whole situation 😀 😀 .
Regards,
Jan-Peter
It is possible to use a clocksignal at the input of the UcD modules, the oscillator will start directly to synchronize on this signal. The only reason to do this is to avoid mixing product or tones. But the HF emission of the UcD modules are low enough, so you normally wil not have this kind of problems.
And using a synchronize module will decrease the loopgain, so this will in a way WORSEN the whole situation 😀 😀 .
Regards,
Jan-Peter
Michel
Try it!!
It playes stereo!
Dosen't even effect the stereo perspective negatively.
The switching freq. and modulation is IMHO not the same . It is like a modulated oscillator. And if you look at the output before the restoration filter, the switching freq. is pritty stable up to high modulation rates. In fact it is difficult to see, on this output, that it is not a PWM made from comperator with adiuo on one input and triang. switch freq. on the other.
Koldby
Try it!!
It playes stereo!
Dosen't even effect the stereo perspective negatively.
The switching freq. and modulation is IMHO not the same . It is like a modulated oscillator. And if you look at the output before the restoration filter, the switching freq. is pritty stable up to high modulation rates. In fact it is difficult to see, on this output, that it is not a PWM made from comperator with adiuo on one input and triang. switch freq. on the other.
Koldby
Kolby,
Let me explain;
In bridge mode stays the modules till a high mod. index in sync. In the case of two different signals the synchronize will loose quit fast, and in this case you will get a lot of IM products between these two signals. Supose CH1 1.2kHz and CH2 1.5kHz, you will see on both channels IM distortion on the boths channels of this two frequencies.
Regards,
Jan-Peter
Let me explain;
In bridge mode stays the modules till a high mod. index in sync. In the case of two different signals the synchronize will loose quit fast, and in this case you will get a lot of IM products between these two signals. Supose CH1 1.2kHz and CH2 1.5kHz, you will see on both channels IM distortion on the boths channels of this two frequencies.
Regards,
Jan-Peter
Koldby,
Just try what Michel said if you want to prove it to yourself, disconnect/ground the input to one module, does "any" signal come out of the module with the disconnected input? hmmmm
Just try what Michel said if you want to prove it to yourself, disconnect/ground the input to one module, does "any" signal come out of the module with the disconnected input? hmmmm
Classd4sure
I would assume the output from the disconnected module would only show residual of the switching freq. !!
And just tried it. Only just before clipping in the other channel, there is some modulation in the disconnected channel If you look at the disconnected output with a scope you can only see it as small deviation in the freq. when he time base is set high enough to see the sw. freq.
If you look with the time base set to the audio signal, you can only see the noise from the sw. freq.
Jan-Peter
If you say so it must be so. But does it affect loop gain in the audio range? And how much IM and at what modulation level?
It is easy to see that the sw. freq. residual is much cleaner if you use the cap.
Maybe it is because the modules are very close in my setup?
If anyone has two UcD very close - try it and tell me if I am hearing ghosts??
Koldby
I would assume the output from the disconnected module would only show residual of the switching freq. !!
And just tried it. Only just before clipping in the other channel, there is some modulation in the disconnected channel If you look at the disconnected output with a scope you can only see it as small deviation in the freq. when he time base is set high enough to see the sw. freq.
If you look with the time base set to the audio signal, you can only see the noise from the sw. freq.
Jan-Peter
If you say so it must be so. But does it affect loop gain in the audio range? And how much IM and at what modulation level?
It is easy to see that the sw. freq. residual is much cleaner if you use the cap.
Maybe it is because the modules are very close in my setup?
If anyone has two UcD very close - try it and tell me if I am hearing ghosts??
Koldby
koldby said:
Right, so that's the argument case and point.
You see it does indeed affect channel seperation/IM/etc. As with zero input, should have zero output, any switching residual you see on it should be 50% modulation and never changing, anything else is noise and distortion. If you really prefer the sound of it like that, who's to say we're wrong, you're the final judge after all. Throw a switch in there to turn on/off and call it an effect.