UCD180 questions

[Joseph K]

Gertjan,

It's post 493 of that page, I've tried to describe how I would measure impedance without the analyzer.

Ciao, George

[Pasi P]

DC-protection of UCD:s have been discussed earlier but i have not found good ready-built solution yet.

I want disconnect power supply lines and using dual mono.

Will this circuit be ok?
http://sound.westhost.com/project33.htm#tests

[koldby]

Hi Bruno (or whoever it may concern)

Wouldn´t it be rather easy to get rid of the input OPamp?

If you put a 2K2 resistor across the noninverting input of the comperator, an equal Z of the two inputs should be the result?

As the gain is only 6db it would be fairly easy to compensate in the preamp..

Koldby

[ghemink]

Originally posted by Joseph K
Gertjan,

It's post 493 of that page, I've tried to describe how I would measure impedance without the analyzer.

Ciao, George

Hi George,

Thanks, I'm doing something similar. My scope has a built in arbitrary function generator and input/output are only a few cm away from eachother. I have not used 50Ohm termination as the line is very short. I have used square waves but I can try frequency sweeps as well. I used a 100Ohm resistor in series with the output to inject a current into the caps and measure the voltage over the caps.

Thanks and best regards

Gertjan

[Bruno Putzeys]

Originally posted by koldby
Wouldn´t it be rather easy to get rid of the input OPamp?

If you put a 2K2 resistor across the noninverting input of the comperator, an equal Z of the two inputs should be the result?

As the gain is only 6db it would be fairly easy to compensate in the preamp..

The gain of the op amp section is 5 (14dB). If your preamp will drive the modulator directly, the op amp can be skipped.

The UcD circuit should be seen as a differential amplifier with 1.8k for the two imput resistors and 8.2k for the two feedback resistors. The input impedance at the noninverting input is 1.8k+8.2k=10k referenced to ground. The input impedance at the inverting input is 1.8k+8.2k=10k referenced to the speaker output. The latter works out as 1.8k referenced to a virtual source of Vin(noninverting)*8.2k/(8.2k+1.8k). In other words, the input impedance cannot be balanced by adding resistors referenced to ground.

[Bruno Putzeys]

Originally posted by Pasi P
Will this circuit be ok?
http://sound.westhost.com/project33.htm#tests

It can be done simpler but it'll work. Make sure to make the circuit such that the relay can't come back on unless the mains is disconnected.

[stef1777]

A question about the anti-ploc circuit from Jan-Peter.

Can I use one circuit to connect two or more UcD180 modules?

I'll have two cases:

- 2 modules with a PSU per module.
- 3 modules sharing the same PSU.

The anti-ploc circuit ground is connected at the star ground.

[Bruno Putzeys]

Originally posted by stef1777
A question about the anti-ploc circuit from Jan-Peter.
Can I use one circuit to connect two or more UcD180 modules?

No problem. The on/off pin is only interested in yes/no, so it's not sensitive to noise.

(I had long been wondering why at Philips "pop noise" was consistently called "plop" until it dawned on me that that's what the dutch called it. So if Philips were french we'd have been speaking of "ploc". Anyhow, before long our japanese customers were calling it "puroppunoizu")

[ghemink]

Originally posted by Bruno Putzeys


..... Anyhow, before long our japanese customers were calling it "puroppunoizu")

Which translates back to "plop noise" so maybe they got that word from the Dutch:-) Like they have inherited many words from the Dutch. Like "otemba" which comes from the dutch "ontembaar" and stands in Japan for a woman who can not be tamed (or something like that). The Dutch speaking here will know what I mean.

Sorry for being off-topic

Gertjan

[stef1777]

New in my desk, a 5 channels UcD180.



5 x UcD180
2134 op-amps and BG NX-HiQ caps
3 PSU (one for 3 channels, one for each front channels)
MBR10100
BHC ALC10S
XLR at input with -12dB switchs for front channels
CC protection circuits with relays at output
WBT and Speakon connectors
4 fuses and 12V PSU for CC circuit and other use.
6 LEDS on front
2U cabinets
15kg

Close to be finished... but already working.

Thanks to Hypex, Schuro, Farnell, ITT, TI, BG, and HH.