UCD180 questions

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#1,821
classd4sure said:


Capacitors block DC. If you have too much DC output from your pre amp, you put a capacitor in series with it, of such a value that you don't lose too much signal, say to form a high pass filter with a cut off below the audio range, something like 6Hz.

Now all DC is blocked. That's AC coupling. Only AC signals may pass.

However, by nature of the capacitor not being a straight wire, it colors the audio signal. You then have two choices, use a better sounding cap for a more pleasing coloration, or, remove the cap, replace it with a wire, and that is DC coupling, because now even DC can get through and be amplified. That's why it depends on the level of DC output from your source, too much can fry your speaker. The accepted level of DC output from an amplifier is 50mV max.

Power, interesting question. Power doesn't only come from the module. The supply itself makes a huge difference, not only the potential of it but the bandwidth of it.

Changing my input cables to those of a proper gauge for interconnect probably doubled the power.

So, all things right, it feels like a solide 200 watts. On my speakers, at 102dB efficiency, with 15" woofers, hell yeah, all kinds of power, but they handle 400W and that would be fun too.

Regards,
Chris
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Ah I see, I get it now. 🙂

Well 102 db sensitivity, no wonder the amp sounds powerful, but remember that my speakers are 13 db LESS sensitive. So they might require more power.


Regards,

Christian
 
#1,822
avr300 said:


I do have a UcD180 setup - and I'm certainly not lacking power. Take a look at it on http://www.frequence.dk/sites/avr300-amp.htm

It's even written in Danish ;-)

/avr300
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Thanks, I have already read that. 🙂

Could you tell me some more about the sound, particularly the bass? My speakers are known to sound flabby and boomy in the bass if the amp driving them doesnt have enough power.
They really need an amp of a higher quality and power than their price would suggest.

What speakers do you drive with that amp?


Regards,

Christian
 
#1,823
@Neutrality,

I'm using difficult speakers just like yours - N804's, 8 ohm nominal, drops to 3 ohms under certain conditions.

N804's even have the bad reputation to lack bass - no so. They might not go deep & boomy, but with the right power they present a good bass sound.

I'm not running UCD180's but UCD400 - it's not only the wattage that counts with low impedance, but the ability to push enough current - The UCD180 is current limited at 10A, but the 400's overcurrent protection is around 20A, and also runs at a higher voltage. UCD700 will go higher still.

This means with the right transformer, the UCD400 can push it's max output power at about 3 ohm I believe - below that, output power will drop because the current has reached max.

So with difficult loads, it all goes down to how loud you want to play without clipping (hitting the current limit...)

I don't know where the limit is - I have the feelings my bass drivers will pop out before the amp runs out of steam....
 
#1,828
pburke said:


and I'm pretty set on using a plastic lunchbox enclosure for the UCD700s now! I always wanted something out of the ordinary.

how about this one - it's even metal....

http://cgi.ebay.com/MINT-Unused-Tag...6235454966QQcategoryZ7270QQrdZ1QQcmdZViewItem

😀
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That's a fairy nice case. With the total build cost it should fit the budget huh?

I have a case with oak sides (IAG?) I only got it because it was fairly local (not cross border), and the aluminum was thick enough for my liking, as in not sheet. I don't like the look of the oak though, too square and bulky, Bruno's looks good, mine doesn't.

Anyway I was telling someone how I didn't like it and they gave me a slab of marble for free. Why the heck not? I just have to cut it to size.

Cheers,
Chris
 
#1,833
OK, so having caught up a little on this thread I see that Hypex are recommending some slightly different grounding arrangements from the norm

Up until now all my amps have had the inputs connected only to the amp boards (no grounding at the XLR input) and then there is a connection to chassis ground from the center point of each power supply and the chassis ground point is then connected to safety earth

This is what I thought was recommended practice.... I don't get any hum on most of my amps despite using a passive attenuator for volume control (the attenuator is connected similarly, ie each channel isolated and passes directly through from input to output without touching the chassis.

So it seems that in the Applications section on the LCAudio website that they recommend instead tying XLR ground to chassis ground, chassis ground to safety ground and nothing else? Might this give better performance based on some of the comments I am reading here?

What are the reasons you would want to / want not to, tie the powersupply ground to chassis ground?

I also have a zappulse amp (cough, cough) which doesn't seem to like my passive volume control. It was fine when I built it with a single power supply the problem is since I added dual mono power supplies, each tied to chassis ground. I'm wondering if this grounding arrangement might fix my issues...

Any thoughts on how best to ground these modules (just to confirm the above?)

Cheers
 
#1,834
Jan Peter:
We have made some pictures of Bruno's own UcD180 amplifier.
Click to expand...

This is probably the oldest UCD amp out there.
Does it have DC speaker protection? :devilr:

Wood sides huh, go figure. Now I'm using marble for sure~!
Click to expand...

I use heavy wood bases in my horrible DIY Al boxes 🙁
After the above comments I guess I will never have the courage to post picks :bawling:

The end of the year will certainly be very bussy 😀 :smash:
We must give some attention to our beloved ones :angel:

Merry Xmas to all...
 
#1,837
...so all I got left now is my trusted UCD400 stereo amp.

I've got a Minidisc deck player here with a variable headphone output - I wonder if I can connect a headphone output directly to the UCD400 inputs, or is that a big impedance mismatch? At least I'd have a digital source this way... could even connect some old CD-ROM drive digitally to the minidisc and listen!

Must... have.... highend... fix.... badly! :bawling: :apathic:

Thanks,
Yves
 
#1,838
Yves Smolders said:
Give attention to beloved ones huh... I did my "good deeds" without I knew it myself.

I just sold my old audio gear on eBay, expecting the new stuff that was ordered.

Just got a mail its not on stock and I'll get it in january!

A month without good Audio!!! :apathic:
Click to expand...


Yves Smolders said:
...so all I got left now is my trusted UCD400 stereo amp.

I've got a Minidisc deck player here with a variable headphone output - I wonder if I can connect a headphone output directly to the UCD400 inputs, or is that a big impedance mismatch? At least I'd have a digital source this way... could even connect some old CD-ROM drive digitally to the minidisc and listen!

Must... have.... highend... fix.... badly! :bawling: :apathic:

Thanks,
Yves
Click to expand...


Got a soundcard and some junk around to rig up some interconnects?
 
#1,839
Sure, I've got plenty of cables & other stuff, don't think for a minute I won't be listening anymore until january 😀

Got myself a Denon 4306/3910 combo. Internal amps for surround and center duties, UCD for the fronts. It's got some amazing room correction stuff I wonder how it will work out!

Eventually I'd like to do my center channel with UCD also. Cheapest way is a 3rd UCD from the same PS (I'm not running anywhere near full volumes anyway, 500VA & 40.000uF should do) - and switch it off when going for pure stereo, using the mute signal.

Problem is that the Hypex HG PS only support 2 inputs for DC protection sensing. I have a schematic on how the DC is implemented on the HG PS, but i'm not sure I can change it myself for a 3rd sensing point.

As a lot of people are going for an odd number of channels (5.1, 7.1) it's a shame that a 3rd sensing point isn't present on the PS. AFAIK it's a diode & a transistor, shouldn't affect pricing too much.
 
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