UCD180 questions

[Bruno Putzeys]

Until recently, toroid chokes having a sharp saturation characteristics were nonexistent. Now they're only hard to get at and a bit expensive (and single-sourced). Most toroids you'll see in class D amps produce a substantial amount of distortion. A normal gapped ferrite design is sublimely linear even if you buy the ferrite from a company called "Happy Sun and Shiny Weather Electrical Goods Trading Co. Ltd." or something of the sort.

Another reason why we don't like toroids is the fact that the windings are external. To get the same level of electrostatic shielding we're automatically getting from closed ferrites (grounded through the clip that holds the thing together) would require an extra metal box round the coil (remember that UcD's secret weapon is its unmatched ultralow EMI).

Also, the length of wire and hence the resistance is greater when using toroids.

For a given current and inductance, there is no size advantage to either toroids or ferrites. Ferrites are more flexible to tailor depending on the actual needs.

As a rule, we match coil current capability with that of the MOSFETs for an optimal design. Neither the coil nor the FETs are a bottle-neck.

[ghemink]

Originally posted by chrisb03


How did you come up with that?

Very simple, the spec says 26dB gain, 20db is a factor 10 and an additional 6dB is a factor 2 which gives me a factor 20. So with a 1.5V RMS signal you get 30V RMS which would be 42V peak output. 30V RMS corrsponds with 112W in 8 Ohm and 225W in 4 Ohm. So full power is achieved with 1.5V RMS input voltage.

Best regards

Gertjan

[Ouroboros]

I'm interested in using the high-power versions (when they are available) to drive a pair of Magneplanar 2.5r panel speakers.

I don't suppose anyone has tried a UCD module feeding Magneplanars yet have they?

[rha61]

Originally posted by Tangui


Hello Alain,

I suppose that you had to cut the existing power supply leads on the printed circuit to be able to use an external power supply for the AD826?
I noticed the AD826 has a very high bias current of 3µA. What input resistance are you using, 10k or 100k? 100k results in 300mV offset voltage! Can this cause problems (operating point, etc...), or am I wrong? The coupling caps are mandatory, then.

Yves

Hi Yves

You're wright , i've put back the 10k resistance since i got some power supply pumping effects sometimes
The 10K R has allowed me to bypass interstage caps again with reasonable 150mV max offset at the output , depending on potentiometer position ( at this level of dc offset , there's no pumping effect )
I just have less gain but still enough

in this configuration UCD+AD826with external power supply+no caps , the sound is simply magical
i simply regret to have not tried AD8620 with this power supply but i'm fed up testing op-amps

alain

[pburke]

Originally posted by Ouroboros
I'm interested in using the high-power versions (when they are available) to drive a pair of Magneplanar 2.5r panel speakers.

I don't suppose anyone has tried a UCD module feeding Magneplanars yet have they?

nope - because us maggie owners know that the USD180 isn't gonna cut it... we're all waiting for the UCD400

I plan to build a 4-channel UCD400 and biamp my 3.5Rs with it

Peter

[DIY_Peter]

Originally posted by richardkrol
Hi all,

I've also been captivated by the magic of the UCD modules and I am planning to use these to power a pair of DIY monitors with an efficiency of about 91,5dB's for 2,83V/m and a smooth impedance of 5 ohms. For those interested, the speakers are the Proteus designed by Tony Gee, see: http://home.hetnet.nl/~geenius/Proteus.html

The plan is to get the following items:

1) LC Audio softstart circuit
see: http://www.schuro.de/preisl-softstart.htm
2) Encapsulated torroid transformer
see: http://www.schuro.de/preisl-trafos.htm
3) Power supply board with 2x 10.000 uF Slit Foils
see: http://www.schuro.de/preisl-ntke10-63sf.htm
4) single UCD180 module

Why not buy the softstart module directly from lcaudio? around 40€ and free shipping...

but you're allready ordering stuff from schuro, so maybe it won't make much difference.
Have you ordered things from schuro before? I was wondering what they charge for shipping to belgium...

[DIY_Peter]

Originally posted by richardkrol
Hi all,

.schuro.de/preisl-trafos.htm[/url]
3) Power supply board with 2x 10.000 uF Slit Foils
see: http://www.schuro.de/preisl-ntke10-63sf.htm
4) single UCD180 module

My question is twofold, the PS board can handle 2x35 volts maximum > what transformer rating do I need to get? 160VA 35V?

I guess they are talking about the ac voltage of the transformer since 35V AC will amount to about 50V DC after rectification. The caps can take 63V, so they are taking some safety marging.

[Jocko Homo]

nope - because us maggie owners know that the USD180 isn't gonna cut it... we're all waiting for the UCD400

Oh, really.........?

Want to guess how many 50 W Class A amps that I have sold to Maggie owners????

I know how much power is required in a typical Maggie installation, and it isn't 400 W. Or any other typical install, either.

Jocko

[jam]

Jocko,

What about electrostatic owners.......... like me? So how many 50W class A amps have you sold?

[JohnW]

Some of us live in shame....

For the past 10 years or so, I've been driving my Martin Logon CLSIIz with "Sample 104" this dear 30W amp was a prototype for Cambridge audio, which got rejected for "Weak Bass". Its retail price would have been about US$150 but featured High current REGULATED supplies, which gives it very good Bass Control and massive sound stage. Unfortunately it did not "interface" well with "Budget" speakers - which require "Loose" amplifier control to achieve their Boomy & bloated Bass.

The morel of this story, Current not "Watts" is need for Panel speakers.