UCD180 questions

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#1,181
Hi All-

I have a pair of the 180's with AD chip and was wondering if I could implement a high pass function on the amp.

I have these modules as part of a 3 way bi-amped speaker and would prefer not to use an additional high pass before this module. If I can get the buffer on the 180 to perform a 6-12db slope I could eliminate another component in the chain all together.

Ideas?

The Louis Erath Feedback controller module for the bass unit has a 2 way elec. x-over built in to cross over the UCD180's but I would prefer to take that HP out of the chain if possible..

Currently the LWE FCN has a hp freq of 400hz but that point can vary considerably. 6.5" mid x'ed-over to 2 tens...

Thank you in advance,

Troy
 
#1,183
Hi richie00boy-

Thanks for the reply.

I was hoping you could filter the feeback loop or implment another part on the input to the amp from the AD chip or what ever... And I "think" cascaded 6db/oct filters would be better than the current "extra" device solution...
 
#1,184
Hi !i
i own 3 ucd 180 modules Version 2 Standard with 5532... I've sucessufully updated my modules with 8620 (+zeners) If i'm right input resistors wich defines input impedance are R13 and R46 on the edge of the board under the input signal connector isn'it ? those 2 resistors are written 1003 (doesn't mean 100k ? but i was thinking it was only 10K... to confirm i've measured 100k with a multimeter between signal - an signal ground and about the same between signal + and signal ground on the sound input molex connector.

So does it means i already have 100k input impedance ? or does impedance change at runtime and i have to replace some resitors to get this ?
thanks in advance for your help...
PA
 
#1,187
pa said:
Yes, it is BZX c 12 Volts smd zeners the 8620 works with a lower voltage...
Click to expand...
Merci,

I did a search for this part at rs-components where I'll probably be ordering more stuff and came up with "Diode, Zener, axial, BZX79, 12V "(BZX79C12A26A). Not smd, but I think that matches my soldering skills better.

Coud you please explain were the zener is supposed to go and what the orrientation of the zener is? You may have noticed I'm not an EE 😉

Thanks again!
 
#1,188
the zeners are d1 and d2 near the two transistors... but i don't think replaceing it with a standard package zener will be much easier, the board is not designed to support it, you could test that on an old pc motherboard before...

the (-) of the zeners are on the same side as t3 (you could see a small white line on the diode).
PA.
 
#1,191
pa said:
Hi !i
i own 3 ucd 180 modules Version 2 Standard with 5532... I've sucessufully updated my modules with 8620 (+zeners) If i'm right input resistors wich defines input impedance are R13 and R46 on the edge of the board under the input signal connector isn'it ? those 2 resistors are written 1003 (doesn't mean 100k ? but i was thinking it was only 10K... to confirm i've measured 100k with a multimeter between signal - an signal ground and about the same between signal + and signal ground on the sound input molex connector.

So does it means i already have 100k input impedance ? or does impedance change at runtime and i have to replace some resitors to get this ?
thanks in advance for your help...
PA
Click to expand...

Without the advantage of being Jan-Peter, it sounds as if your resistors are indeed 100K. The 3 is the power of 10 you use to multiply the significant digits, hence 100 * 10^3 = 100K.

I'd be really surprised if input impedance changed significantly at runtime, modulo some small effects due to the opamp being powered. Outputs do change impedance under power, but rarely inputs.


Cheers,
Francois.
 
#1,196
Originally posted by Ivex;
Hi Jan-Peter,
I want to try Deat_Time_pot like in the UcD400, but for UcD180. Now this resistor are 470ohm, how much danger would be 300ohm, without mosfet driver modification for the "adaptive dead time" ability?
Click to expand...

300 ohm is too low. I would suggest to use a solid resistor of 330 ohm and in serie a potentiomer of 250 ohm. When the pot is in the middle of the range you have 455ohm, you can change the resistance from 330 to 580. In this case you have a nice range.

But be carefully, when the resistance is too much different from 470 ohm your idle current goes very fast up!

Regards,

Jan-Peter
 
#1,197
Luismax said:
What about this for speaker protection?

http://www.wnaudio.com/lspro.html
Click to expand...


Does anyone see any problems using one of these with the UcD's? Here's a what WN say about the module. I'm more concerned about the fact that it disconects the speaker at power up and before power down. If ok, that means I can just keep the UcD module power on switch permanatly on. Correct?

" In addition to protecting loudspeakers from DC offset voltages the White Noise module keeps the loudspeakers disconnected for a few seconds after switch on, allowing the power amplifier circuitry time to stabilize and eliminating switch on thumps. The module also disconnects the loudspeakers before the main supply voltages start to fall at switch off, thereby eliminating switch off crashes and squeals. "
 
#1,200
And for the /on issue, you can also use Jan-Peter's little schematic with the two diodes.

For the more electromechanic types (like me!) you could try this:

Get a soft-start (chances are you need one anyway) - put a relay in parallel over the existing relay that shorts out the soft start resistors.

Use this relay to connect /on to GND.

Now your modules turn on after the power supply has settled, and they get switched off at the moment the mains is gone.

...and as for "bleeding" the caps, the UCD's even when in "standby", seem to consume some power. my 2x22.000uF are drained in a matter of minutes.

To complete everything, velleman makes some nice DC protection units, mono, independent. They use a normally-closed relay and they disconnect output at presence of DC. Bad side is (didn't test it yet) that the relays seem to be low quality (not audio rated) so the normally closed contact may "weld shut" when it's needed, and the contact point might infuence sound quality.

For the daring, JP told me that in lab tests, when one FET failed, the other one went with it, so chances of prolongued DC on output seem small.
 
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