active crossover with UCD problem

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#21
ackcheng said:
I am using my computer to do the digitalcrossover. With a program called acourate

www.acourate.com
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Thanks Ackcheng.

Are u going to use FIR filter? I'm very interested to heard the result.

Though ZaphK didn't tested the Raven R2, I suppose it'll behave very much like Aurum Cantus G3. Distortion is likely to rise gradually below 4KHz. How low it could be crossed really depends how loud u'd like to play.

2KHz might be ok only for Tsai Chin or Lily Chan. For big orchestra I suggest 3.5 or 4KHz, even with steep FIR filter.
 
#22
patriz said:


I use ucd 180 and 400 for my multiamped high sensitivity compression drivers system and with hypex power supply you can hear just a very very low bump when turning on and absolute nothing when turning off. Once I tried high quality capacitors betwen ucd and the drivers and my legs are still trembling for what I heard when I switched on the amp. The same happened to a friend of mine so I never would do that again.
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What happened with the cap between UcD and driver? Maybe the UcD needs to see some resistive output load?

Hopefully Jan-Peter can comment? I use the UcD180 to drive tweeters directly (conventional voice coil type, not ribbons with transformers) , so no caps in series. Had no issues for more than 2 years or so.

It seems Arthur had no issues with the cap, however, if some form of resistive load is needed, maybe he should add a power resistor (how many Ohm should do (100 too high?) directly at the UcD output to prevent potential issues as you experienced.
The larger the better (you don't want to burn a lot of power in that resistor))

Thanks and best regards

Gertjan
 
#23
ghemink said:



What happened with the cap between UcD and driver? Maybe the UcD needs to see some resistive output load?

Hopefully Jan-Peter can comment? I use the UcD180 to drive tweeters directly (conventional voice coil type, not ribbons with transformers) , so no caps in series. Had no issues for more than 2 years or so.

It seems Arthur had no issues with the cap, however, if some form of resistive load is needed, maybe he should add a power resistor (how many Ohm should do (100 too high?) directly at the UcD output to prevent potential issues as you experienced.
The larger the better (you don't want to burn a lot of power in that resistor))

Thanks and best regards

Gertjan
Click to expand...


actually I don't remember if it was switching on or off.
Giorgio
 
#24
patriz said:


I use ucd 180 and 400 for my multiamped high sensitivity compression drivers system and with hypex power supply you can hear just a very very low bump when turning on and absolute nothing when turning off. Once I tried high quality capacitors betwen ucd and the drivers and my legs are still trembling for what I heard when I switched on the amp. The same happened to a friend of mine so I never would do that again.
Click to expand...

Strange....this can only happening if the capacitors are charged by with DC. The very first batches of the UcD modules did had a small DC voltage at the output when there was NO load. Perhaps you have one of the first modules? Anyway this particuler DC output voltage charges the coupling capacitor. When you switch the amp on, the capacitor will be discharge again and this creates the thump.

Jan-Peter
 
#25
Jan-Peter said:


Strange....this can only happening if the capacitors are charged by with DC. The very first batches of the UcD modules did had a small DC voltage at the output when there was NO load. Perhaps you have one of the first modules? Anyway this particuler DC output voltage charges the coupling capacitor. When you switch the amp on, the capacitor will be discharge again and this creates the thump.

Jan-Peter
Click to expand...


They are early boards but obviously they were connected to the load
 
#27
While I can now play with the tweeter, I am still gettng the "pop" when turning on.

I have connected a 27uF cap in series with the tweeter and i guess, this is what's happening! In stead of puting 1K resistor across the + and -, can I just put the 27uF on the over terminal of the tweeter? I just thought that the -ve terminal is grounded and my be it will discharge itself?
 
#31
Raven tweeters are a dead short at DC.

With only a few millivolts of DC off-set several amps will flow and the overcurrent protection will trip.

Always use a protection cap.

If the amplifier needs some DC resistance at its output, hang it directly on the amplifier output (before the cap).
 
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