UCD180 questions

[classd4sure]

The amps they tried cover the spectrum of output impedance nicely, right? Tripath being the highest, UcD being the lowest.. That should only make the UcD shine that much more, but I'm unable to think of any way it would skew the outcome the other way.

I don't know, I get the feeling in a little while they'll have a post here saying "we fixed our UcD and...... WOW"

Here's a funny question:

My speakers have a built in passive crossover network, I think the first thing the signal see's is a cap (could be wrong there), can't go more into detail on it than that I'm afraid.

What are the chances a passive crossover acts upon the UcD's feedback loop, and or, filter, in an adverse way?

[tiki]

Hi,

if somebody understands German, there is a paforum.de, which is sometimes very interesting to read. They have some problems, same as in the hifi range, but in a multiplied manner. One example:
The bass reproduction seems to be louder or, if one wants, more kicking, if the amp or the speaker (more likely) produces even harmonics. This could be one effect, differing the amps "sound" due to the usage of not appropriate speakers for that test. Maybe, the differences between the amps would get smaller, driving speakers directly in an active configuration.

I also do not trust any "not blind" tests, the risk of different conditions and optical effects is too high ("And now we are listening to the powerful looking aluminum case"). Unless I do not switch quickly between the D.U.T.s, I am not able to compare the devices seriously.

Listening and "measuring": Years ago I looked for a cheap recording possibility - I decided for a hifi-video recorder. Even with passive speakers in the 2000 DM-range, I was not able to decide, which sound was better, CD or the recording, even while switching the inputs many times. Yes, there was a slight difference, but I could not say, which sound was the original, if I did not look at the switch. Sometimes at home I tried a pure sine with the recorder - what a terrible disappointment. With rising frequency the head switching noise became louder than the signal! But I could not hear that behaviour with normal audio signals. Ok, today I use CDs...

Regards,
Timo

[rc]

Hi peranders,


I found this review quite strange, specially after reading acme's
own comments in another thread:
http://www.diyforum.net/phpBB2/viewtopic.php?t=1725

"Blev Medlem: 12 Sep 2002
Inlägg: 51
Hej,

Hmm, vilken lät då egentligen då bäst av de tre förstärkarna?
På den nyss genomförda, mycket trevliga Blasten så gjordes ett litet
försöka att bringa klarhet i frågan. De tre förstärkarna var nästan
helt identiska, så trots att man såg vilket som för tillfället var inkopplad, så blev
det ändå lite av ett "blindtest". Ingen visste alltså på förhand vilken förstärkare som satt
i vilken låda.
Jag tror de flesta hade ganska svårt att höra någon skillnad överhuvudtaget mellan
dem till en början. Trots att vi skiftade 1-2-3 och tillbaka flera gånger. Efter ett stunds lyssnande
(samma låt gång på gång, puh) så kunde man börja höra små skillnader mellan dem.
Jag fick intrycket att den som de flesta tyckte lät "bäst", var efter avslöjandet ICE-power 500A, följd
av Hypex UcD 180 och till sist Tripath.
För att beskriva ljudet från de tre skulle man kunna ösa på med hifi-floskler som man läser
i diverse sk "hifi-tidningar", men det tror jag att jag hoppar över icon_wink.gif .

/Peter
_________________
Rör suger...
"

A quick translation of this into English:

"
Hi,

Hmm, which one of the three amps did really have the best sound?
On the recently carried out, very nice Blast [a sorf of Gathering, RC comment]
there was a test made to try and figure this out.
The three amps where almost completely identical, and even if
one could see for the moment which [amp] was connected, it
still was sort of a "blind test". Nobody knew beforehand which
amps was in which box.
I believe most people had difficulties hearing any difference at all
between them in the beginning. Even though we
shifted/switched 1-2-3 and back several times. After listening for awhile (same
song over and over, phew) one started to hear small differences
between them.
I got the impression that the one that most people though
sounded "best", was after revealing the ICE-power 500A, followed by Hypex UcD 180 and last the Tripath.

To describe the sound of the three [amps] one could throw plenty
of"hifi-high-sounding empty phrases that one reads in the different
so called "hifi-magazines", but I think I'll skip that icon_wink.gif.

/Peter
_________________
Tubes sucks...
"


I searched the forums to try and find what kind of equipment
they used for the test. The only thing I could find was that
they had 60.000uF caps and a 500VA transformer in the amps.
I find it interesting complaining about how "hifi-magazines"
do bad reviews and then fail to write what equipment they
themselves used to test them.

Maybe his tagline could also be a clue, that's why I translated
it too :-)

I myself am hoping to receive my first pair of UcD180+AD8620 this
week to do my own comparison against my Primare system.

Jan-Peter: I received an email reply from Niels and Jorrit, but none of
my smtp servers seem able to send emails to your domain for the
moment (?).


Best regards,
Roberto

[stef1777]

In hifi land, the deaf are king.

Me first!

[stef1777]

Originally posted by Jan-Peter


You can put the /ON always on the GND line, but you can have some noises when you switch the amp off. Because the capacitors are discharging quit slow so you don't have a fast/sharp moment when the amps switch off. Please use the circuit in the attachment, every small NPN transistor will work. AC1 and AC2 are the secondairy voltages.

Regards,

Jan-Peter

Hi Jan-Peter!

I replaced the original NE5532 with OPA2134 on the modules. Works fine. I also replaced the 22UF coupling caps with Elna Silmic. Bad sound. I shunted them (I only have 12mV at the ouput). Nice sound now.

Since I removed the coupling caps, I have a small "clic" in the speakers when I power on the equipments.

What is the best to modify your auto-mute circuit to have a 2 seconds delay at power on? May be just add a polarised capacitor after R1 between the line and the ground?

Stef...

[peranders]

Originally posted by rc
Hi peranders,


I found this review quite strange, specially after reading acme's
own comments in another thread:
http://www.diyforum.net/phpBB2/viewtopic.php?t=1725

Maybe ACME has changed his opinion? A review is a review nothing more.

Lars' ZAPulse got a bad review in danish/swedish High-Fidelity. Thy looked at the distortion figures (first?) and got then they wrote their review. Nevertheless I'll believe lars has pretty many satisfied customers despite the opinions from two, three people.

I bet also that in the last test the guys played pretty loud and maybe pushed the weak UcD180 much compared to the more morefull 500W ICE and Tripath.

[classd4sure]

Hi,

Nice work on that RC,

snip..
The three amps where almost completely identical, and even if
..snip


Can you really compare a 500W amp with a 180W and call it near identical?

On that note, I trust no one just tripped over a three month old article and this is a recent publish..... why didn't they at least use a UcD400 and give it a level playing field, it's been out long enough.

I also take issue with the "almost completely" if it were a serious review we'd see alot more about what equipment/parts/methods were used, possibly a section that goes something like "at first were disappointed with Hypex, so we tried this this this this and this and it got a little better but we still think it sucks.... or it really came alive after we realized our mistake, or discovered what it likes."

I can't give that review any credibility at all as it seems the average high school science fair project is more scientific than that. I thought that was just someone in a forum, hard to believe that garbage qualifies for a magazine?

I give their review a big F, regardless of if I agree with it or not, hope that's not their day job. The only good that came of it, stirred the ol thread up again

[classd4sure]

HI Stef,

I dont' think a delay will help remove that little click you're experiencing now, it wouldn't change the DC offset you have with those coupling caps removed.

Maybe you could mask it by only turning the amp on when there's an audio signal present though.. ?

[stef1777]

Originally posted by classd4sure
HI Stef,

I dont' think a delay will help remove that little click you're experiencing now, it wouldn't change the DC offset you have with those coupling caps removed.

Maybe you could mask it by only turning the amp on when there's an audio signal present though.. ?

No sure. If the mute is off at start, nothing will go to the speakers. The "click" seems to comes from my others equipments.

My UcD180 mono block are finally finished, tested and tweaked.

[Jan-Peter]

Stef1777,

Very NICE

This is what we like to see!!!

Regards,

Jan-Peter