UCD180 questions

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#121
JohnW said:
This then leads to the next question - do the FET’s have to be "Avalanche rated" – or will "normal" FET’s be OK?
Click to expand...
They need some avalanche rating, otherwise you're designing in a vacuum. That most modern FETs are an order of magnitude more "rugged" than what you need for absorbing "class D type overshoots" is not a guarantee for FETs with absolutely no mention of avalanche capability to function correctly in this context.

I thought edge termination was a recovery dV/dt related affair though, not something with avalanche. Avalanche rating was largely influenced by epi thickness (again if i remember well). The guy told me this because if I could live with lower avalanche ratings he could get me a lower Ron for the same silicon area (and hence smaller parasitics). This could suggest that if this is taken too far (to make the cutest, smallest, fastest and lowest Ron FET) the avalanche capability might well end up unsatisfactory.

Cheers,

Bruno
 
#122
Ser. no. 10 & 11

Hi!

I'm new here and this is my first post here. I wanted to share my experience with the UcD180 modules, which have been playing nonstop since I first fired them up more than a week ago, or is it two weeks now? I don't know and I don't care. What I do care about is the level of unbelievable pleasure the modules are giving me. 😀

BTW I'm the proud owner of no. 10 & 11. 😀

If there are any Scandinavians out there who can read Swedish and who would be interested in reading about my project, I have written quite extensively on the subject and have even started a few threads describing the Hypex UcD180 modules and I have also posted a few pictures from the building process in the DIY section.
http://www.hififorum.nu/forum/topic.asp?TOPIC_ID=31228
http://www.hififorum.nu/forum/topic.asp?TOPIC_ID=31377

In short, I can only congratulate Hypex on the UcD modules, take my hat off and say that the level of details and presence is far far beyond my ability to even try to express in English. What I can say is that it almost scared me and definately overwhelmed me when I listened to them the first few days, although I felt there was a bit of harshness in the presentation the first two or three days. But after that, the edges smoothened out and now I'm in HiFi Nirvana, or at least on the porch to Nirvana, since there are a few things left to do before I enter completely! 😀

One of those things is that I need to buy, or better still, build a multi-channel passive attenuator with at least seven balanced in- and outputs, controlled with preferably one pot.
The thing is that I use a Behringer UltraCurve DEQ2496 and two UltraDrive DCX2496, which will drive each JBL driver active. (Four on each side, or maybe three plus the low end below 63Hz paralleled in mono)

If anyone has any suggestions on this, please feel free to give me a push in the right direction, if it's not too expensive.

I don't know if this has been addressed before, or not. But one other thing I would like to share is a wish; if it's possible of course, and that is to change the position of the 2'nd and 3'rd pin on the small connecting block. If that would be doable, then it would mean that a signal cable, from a CD-ROM drive would fit right in simply by cutting one in half and solder the wires where they belong. 😉
Just a thought.

Another thing I have pondered on, is if it were possible to give customers the option of a more economical shipping alternative.
For the most part, it is not necessary to have them delivered the day after, if that would reduce the shipping cost a bit.

/Roland
 
#123
Hi Bruno,

MOSFET designers are a real strange crowd of people – ask them a simple question and you can be sure never to receive a straight answer :headbash:

My understanding is that reducing the Epi thickness lowers the Gate threshold voltage, thereby reducing the RdsOn value. However this comes at the expense of increased Gate charges – including the reverse miller capacitance :bawling:

It seems the edge termination is critical for the avalanche performance – but I’m no FET designer :scratch:

Cheers,

John
 
#129
JohnW said:
My understanding is that reducing the Epi thickness lowers the Gate threshold voltage, thereby reducing the RdsOn value.
Click to expand...
Hi,

Something must've gone wrong in transmission...
The epi(taxial) layer is the layer of p- silicon that is put on top of the raw p-- wafer and into which the actual fet is fabricated.

The threshold voltage and other gate characteristics are determined by the gate oxide, which for lack of a better word is called "the gate oxide".

Cheers,

Bruno
 
#130
peranders said:
:cannotbe: I saw now something at the bottom of the page at hypex.

As I understand they have +- voltage and the load is single ended. What is the difference between this and a full bridge? I'll guess there are differences in many things, emission?
Click to expand...


Welcome to the dark side Peranders, you'll never go back.
Originally it was "Ultimate Class D" and now it's "Universal.." but..
it's pretty much the ultimate today anyway. Have you seen a simpler amplifier, witch such good specifications, and such good sound?

You're right it's just a half bridge, the usual advantages can be had by going with a full bridge. Power supply pumping immunity, less noise, more power.

Thanks for your endorsement for the class d forum, best to stick us in our own little corner before we take over 🙂
 
#132
classd4sure said:



Welcome to the dark side Peranders, you'll never go back.
Originally it was "Ultimate Class D" and now it's "Universal.." but..
it's pretty much the ultimate today anyway. Have you seen a simpler amplifier, witch such good specifications, and such good sound?

You're right it's just a half bridge, the usual advantages can be had by going with a full bridge. Power supply pumping immunity, less noise, more power.

Thanks for your endorsement for the class d forum, best to stick us in our own little corner before we take over 🙂
Click to expand...
I think class D is where digital photo is today. Give class D a couple of more years and we will have something which can meet real high-end.

I think class D is exciting but also difficult. I'm thinking of RFI/EMI mostly and what this affects equiptment.
 
#133
peranders said:

I think class D is where digital photo is today. Give class D a couple of more years and we will have something which can meet real high-end.

I think class D is exciting but also difficult. I'm thinking of RFI/EMI mostly and what this affects equiptment.
Click to expand...

OK, out with you!! 😉

I think it not only meets real hi-fi now but defines it.
Really every class of amp isn't without its difficulties..

See, I can tell you've looked into it very little, (not at all) and those are rather strong statements to make considering that.

With a balanced filter and proper design techniques, RFI/EMI... won't be very different that of your cell phone, monitor, pc power supply... etc.

Give it a chance you might change your mind, is what I'm saying.
 
#134
I think there are two facts that delayed the evolution of class-d amps:

1. ) Availability of suitable components, this problem can be regarded as solved.

2.) Engineers who work in the switchmode-area are usually not audio enginners. And much worse most audio engineers lack the lateral thinking needed for the development of class-d amps. But this one is solved also nowadays.

BTW: The oldest patent proposing a really cool class-d topology (with the inclusion of the output filter into the NFB loop) is from the late seventies. At least two professional products are available that use this topology.

Regards

Charles
 
#136
Hi Guys,

I have been a way for a few days , sorry for the late reply!

Roland (Paradigm),

Nice to hear about your experience!

Many thanks for your congratulation. We are manufacturing for almost 10 year audio power amplifers (besides my 15 years of personal hobby experience), and during this time I have seen a lot of Class-D amplifiers. When I test an amp on the workbench I always first put a dummy load on the amp and a sinewave generator together with an oscilloscope. To see how much power we can get out of this amp and if everything looks ok. By testing the Class-D amplifiers I was always very disappointed with the outputsignal of this kind of amps, a lot of HF-switching noise and an awful clipping behavour.

Till I get the opportunity for a demonstrating by the Philips Labs in Belgium of the Universal Class D amplifier. On that moment I saw for the fist time a Class-D amplifier with a very clean outputsignal, who runs in clipping very nice, and showed a very good 10KHz rectangular wave at the output.

After a listening test and a comparing with our own analog amplifier I was convinced and decided to use this technique!

Roland, can you show us your pictures on this forum? I am quit curious....

Peranders,

Yes, indeed we use an half-bridge output. The advantage in comparison with a full bridge is;
- only one outputcoil.
- a real grounded output. Not a positive and negative outputsignal.
- less EMC output.
- no need for an extra powervoltage.

Class-D is were digital photos are at the moment? Interesting comparation 😉
I guess for this discussion it will be the best Bruno could jump in.
I am not such an expert in true High End Amplifiers

Regards,

Jan-Peter

www.hypex.nl
 
#137
Jan-Peter said:
Hi Guys,

I have been a way for a few days , sorry for the late reply!

Roland (Paradigm),

Nice to hear about your experience!

Many thanks for your congratulation. We are manufacturing for almost 10 year audio power amplifers (besides my 15 years of personal hobby experience), and during this time I have seen a lot of Class-D amplifiers. When I test an amp on the workbench I always first put a dummy load on the amp and a sinewave generator together with an oscilloscope. To see how much power we can get out of this amp and if everything looks ok. By testing the Class-D amplifiers I was always very disappointed with the outputsignal of this kind of amps, a lot of HF-switching noise and an awful clipping behavour.

Till I get the opportunity for a demonstrating by the Philips Labs in Belgium of the Universal Class D amplifier. On that moment I saw for the fist time a Class-D amplifier with a very clean outputsignal, who runs in clipping very nice, and showed a very good 10KHz rectangular wave at the output.

After a listening test and a comparing with our own analog amplifier I was convinced and decided to use this technique!

Roland, can you how us your pictures on this forum? I am quit curious....

Peranders,

Yes, indeed we use an half-bridge output. The advantage in comparison with a full bridge is;
- only one outputcoil.
- a real grounded output. Not a positive and negative outputsignal.
- less EMC output.
- no need for an extra powervoltage.

Class-D is were digital photos are at the moment? Interesting comparation 😉
I guess for this discussion it will be the best Bruno could jump in.
I am not such an expert in true High End Amplifiers

Regards,

Jan-Peter

www.hypex.nl
Click to expand...



Hi,

I would have thought the main advantage to a half bridge is reduced cost, but it suffers in other areas with respect to a full bridge. I was also under the impression that a full bridge has less EMI.

I'm not sure what you meant by no extra power voltage, you don't operate it from one rail do you? If so, don't you sacrifice your real grounded load. Maybe I misunderstood?

All that aside, which one should sound better?
 
#138
Jan-Peter said:
Class-D is were digital photos are at the moment? Interesting comparation 😉
I guess for this discussion it will be the best Bruno could jump in.
I am not such an expert in true High End Amplifiers
Click to expand...
What I ment is that it's a real alternative now. 4 Mpx with very good optics are OK for many applications.... but not all. Not even 10-14 Mpx isn't the same as film. The very main thing is the power consumption of the camera :bawling:

So what I mean is that Class D has potential not only for bass or low-fi or mid-fi.

I wish you good luck with you modules, they sure look nice. Can't you supply as with more detailed photo?
 
#139
Jan-Peter said:

Yes, indeed we use an half-bridge output. The advantage in comparison with a full bridge is;
- only one outputcoil.
- a real grounded output. Not a positive and negative outputsignal.
- less EMC output.
- no need for an extra powervoltage.
Click to expand...
What about using four transistors which are the same compared to one P-channel and one N-channel which never (by nature) can be alike?
 
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