UCD180 questions

stef1777 said:


With 2 black flat M3 bolts.

UcD_box-side.jpg


Stef1777
That's exactly how I did mine in my temp enclosure seems to work very well no temperature problems at all even at high volume for long periods. Mine does not look anything like as good as your, well done with your monoblocks.

Now how do they sound?

Could you remind me what those power supply modules are? I don't recognise them.
 
kvistarn said:
ok, but when i mailed hypex i got a reply saying that 13-14vdc on the outputs are normal without any load connected....
I have +48v and -48v... what do you mean?
so power on the inputs means worthless module... hm thats sad.

About that 14V on the output being normal without a load connected, explanations will be welcome! 😕

As for the rail voltages if they are both ok well it must be something else. In any case the module is definitely defective if you see other than zero voltage on its inputs.
 
When the UcD is powered on but not switched on yet and without a load you have an high impedance 14VDC at the output. This comes from an internal bootstrap circuit who creates a powersupply voltage for the Fet what is connected to the positive voltage. Is completly removed when you put a small load to the amplifier.

In the UcD400 we have mounted a small 47k resistor between the output and V-.

Nothing to worry very normal.....


Regards,

Jan-Peter
 
More explanation;
Connect +45V / 0 / -45V to the UcD180. Do not yet connect the /ON line to ground. So the voltage is connected and there is no load at the output of the amplifier. Now there is an +14VDC at the output, because of the internal bootstrapcircuit. When the amp is switched ON this voltage is directly removed, or when you connect a load to the output it will be also removed.

If you don't like this you can even solder a 47K resistor between -45V and the output, the voltage will go to zero and has a high impedance. In a way it will even reduce the small thick what you hear when the amp is switched 😉

Regards,

Jan-Peter
 
wytco0 said:
Could you remind me what those power supply modules are? I don't recognise them.

Custom made. Very basic circuit.

PSU for ONE UcD180.

4 x 10000UF 63V BHC slit foil
2 x MCap 2.2UF
4 x IR hfa25pb60
4 x Wima MKP2 22nf 100V
1 x slime line toroid 160VA 2 x 32V (I got 47V at the UcD power connectors)
 

Attachments

  • alim-droite.jpg
    alim-droite.jpg
    42.8 KB · Views: 1,237
Oops

Jan-Peter,

Snorry for the typoo, swomtimes my flingers get tangled in the kyeboardn.

The reason I mentioned Philips is that I've on more than one occasion from experienced diy/pros that Philips caps are very high quality for a reasonable price. True?
 
I have bought big philips caps for psu in the past at Display in Utrecht, but the decided to stop selling to endusers a while ago. I'm assuming I can get my hands on them in Utrecht at Radio Centrum Electronica in the town centre. I may have time o visit them next thursday (got to get some other stuff as well), but give them a call if you want to find out quickly what they have.


So who do I have to blow around here to get an opinion on psu caps?:bigeyes:
😀
 
AD8620 and lack of Bass

Hi All,

I know that the debate has been raging here about the op-amp at the front of the UCD400 and can be put as AD8620, this may not be the saviour we all think. Because of the compensation scheme used for the op-amp, the AD8610/AD8620 parts have a pretty high LF noise corner and are much much worse than most other competitive low noise bipolar amplifiers in this application. This results in a rise in noise floor in the bass region and is pretty damned audible. The JFET input is nice because of the lack of RF folddown compared to bipolar, but it doesn't outweigh the bass problem.

Simple fact - Good bass is a fundamental to good hi-fi!

Suggest that we all look at a discrete differential stage that will not degrade the sound on the UCD. Anybody got any tried and tested circuits here to try?

F.
 
No answers to my question yet. Is this because:
1) this question has been asked and answered ad nauseum;
2) I am supposed to ask them elsewhere;
3) there is a complete lack of knowledge on Philips caps;
4) there is a complete lack of sense of humour.
 
hmmmmm 1, 2, 5 (you're not my type), and 6 (maybe they haven't tried them, since you asked about a few specific caps).

If you go through this thread you'll find alot about what makes a suitable cap for a power supply, not so much about which cap to use.... it is DIY after all. The specs look real good on those though, I'd give em a try.

This thread has grown to insane proportions as well (did you read it all? Seems few else want to either, it's hell to search through when you know what's there.)

For that reason you should try asking future PSU questions in this thread:

http://www.diyaudio.com/forums/showthread.php?s=&threadid=44515

Cheers