UCD180 questions

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#2,141
some comments

Building an UcD on a piece of wood is NOT a good thing. Same as any other piece of audio equipment it needs to be "shielded". And ... although efficiency is some 90% there's still heat which should be taken care of. The least thing is mount the UcD on a piece of aluminum.

The remarks on the sound quality are a bit off the mark. Maybe someone is used to bad controlled, i.e. distorted, bass sounds. The Ucd gives a marvellous bass control. In the beginning it might give you a feel of less bass but I think you're just missing the distortion of your old system.

The transformer should be considered as giving twice the power of any class A/B-amp because of the high efficiency. So a 160 VA transformer may result in an effective power of around 140 Watts at 4 Ohm. In a "normal" listening room and using loudspeakers with an efficiency of 89 dB/1 W one might blow out the windows!

Indeed the input capacitor is not the best part in an audio chain. If a better op amp is used and if the source doesn't have a significant set off voltage that capacitor may be shorted. In doing so the frequency curve at full power will be straight from 1 Hz and up!

We deliver a stereo amp with 2 x UcD180, a different op amp at the input, a Wima capacitor (just to be sure no DC can be put in), a 225 VA transformer for both channels and all customers are happy with it.
 
#2,142
I experimented a lot with the Tripath eval-modules a couple of years ago, and found them very sensitive to PSU-changes.
And a bigger VA trafo was always better (go figure...).
Caps make a difference too. More is not always better...

And for change in bass, it is a common feeling that these amps have less, but it is usually because of better control.
To check, add a 1-2 ohm power-resistor on the speaker-wire, and the bass will get sloppier again...

Arne K
 
#2,143
Hi Guy (so strange to speak in English with french person !!!),
I am agree with when you say it's a "ST" version of the UCD. I spoke about this on another forum, in French, an one guy tried another transfomer. He said that he didn't find a "big difference"....🙄

Firstable, i will modify the PS of the AOP with the help of the *.pdf file on Hypex site then i will order LM4562 (if i remember....:whazzat: ) and change it.

@ Johnrtd : as you say, building an amplifier on a piece of wood is not the better way the "quitessence" of the sound !!!!!😀 I just wantd to hear it !:angel:

@ Cobra2 : i didn't know this tip !!!!!😱 What do mean by "power-resistor" ? Could you advice me a value, a brand, etc..?

Thanks a lot guys for your replyes !!!!!
 
#2,144
I found in my mess a 1R - 10 Watts MOX resistor. I gonna solder it on the + speaker cable and will telle you after ! 😉 I can do this only once coze i have only 1 resistor !!!!

For the mod on PS HG (removing via), i will take phototo show you the difference between the 2 version (1 is mine and the other is on Hypex site...)
 
#2,146
So, i soldered this resistor and in the fact, the basses are more "punchy". Not a lot but little bit. I did 2 cables and switched the both. Like this i can compare quickly. It's not like before but it's better.
"Why have you bought theses amps if you want the same sound like before" could you ask me ! You can ask !!!!😀 But will not be able to reply.... I don't look for the same sound than before but i am used (and maybe like) the punchy basses. Not like in Techno music but.....punchy basses !!!!😀

Roger, nice to see you here !!!!!!!!!!!😉 Always nice to speak with you. As you told me on the other forum, the basses have better control and i don't have this distorsion who makes the bass more present, pleasing to the ear. With the UCD, it's more "inside" the music, well mixed with the rest of the sound and i appreciate.

I feel the same difference between the HK and UCD than before with my "old" speakers JMLab Chorus 725 and my Scanspeak based DIY speakers. The "Shirel" (the sweetie name of my speakers, thanks Michel aka "Angelilo") gave me the impression than something was missing in the music. But after few weeks, i definitely loved my Shirel. I think it's what's happenig with the UCD. It's more contreolled and i am not used to hear this sound....:angel:
 
#2,147
ucd considerations

Hi,
Just some questions, I think after reading thousands of reviews and articles that the ucd180's are for me, but I still have a couple of queries that would help if anyone can be so very nice.....
using 160va tx (for low power) would I get better results using a single amp or two for biwiring off the same tx...thoughts.
Also as my sources are unbalanced could I slightly "botch" (excuse the terminology) the board to accept a single channel op-amp at the input buffer and tie the ucd modulator to signal ground, the pre-amp will be integrated and so shouldnt be an issue with grounding hum, I think I can put a schematic together but any considerations would be greatly accepted.
thanks all for your help

TAWN!
 
#2,148
perhaps as simple as this or perhaps not, I will sertainly be after four of these amps, although opinion would be appreciated there is nothing like finding out for yourself
if my schematic is BS please tell me I suck and throw myself in the garbage can......
Thank you
 

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#2,149
I don't know if your schematic is OK but why don't you just do what Hypex recommend in their application note for unbalanced input? http://hypex.nl/docs/wiring.pdf

And quote from Bruno:
Here's the full recipe for wiring up an RCA chassis part:
*Use non-insulated RCA chassis parts. They will serve as the chassis connection for the whole amp. You don't want to have the whole amp floating in the chassis or you'll get one heck of a buzz when you leave the inputs open.
*Make no other chassis connection elsewhere, but otherwise wire the whole thing normally.
*Preferably use shielded twisted-pair cable, such as microphone cable.
*Tie pin 1 of the module's input connector (J7) to the RCA signal pin using one of the two conductors.
*Tie pin 3 of J7 to the RCA ground lug using the second conductor.
*Tie pin 2 of J7 to the RCA ground lug as well using the cable shield. This step insures the amplifier is no longer floating with respect to chassis.

This method insures that any ground currents flow through the shield, not through the "cold" wire on pin 3.

If you have a substantial personal preference for using 3 separate wires instead of a shielded twisted pair, at least twist the 3 wires together.

The problem with unbalanced (RCA) connections is obviously the sensitivity to ground loops. Because of this, you should not connect the chassis to mains earth. Instead, follow double-insulated construction methods on the primary side for safety.

There are a few tricks to make an RCA input "pseudo differential" using the differential input of the UcD module, but I'm afraid to "float" them here because that will cause more confusion. Besides, the above description is the most solid because using uninsulated RCA parts also keeps your amps from RF break-in.

Having said all that, it is always best to use XLR inputs and build a "converter cable" (see new doc on Hypex site) that extends the differential sensing trick all the way to the pre outs.
Bruno
Click to expand...

If your pre is integrated then you would connect it as you would a RCA. I would not mess with the UcD's input stage but if you know what you are doing maybe that's a possibility.
 
#2,150
So, guys, i am back !😀 I let the UCD180 working couple of day, the 2 channels still on a piece of wood 🙂apathic: ) but i did 2 mods on them :
- i soldered 3 wires for direct AOP supply
- i changed AOP for LM4562

Now, i can "listen" music and my big monster aka HK AVR 7000 is in is box !😉 These 2 mods have changed the quality of the UCDs. Next mod will be the 2 small output caps. I will remove them and solder a strap.

See you next time for a "compte rendu"( in French !!!😀 )...

Olivier
 
#2,152
Well a couple of reasons, why I would prefer to do things the awkward way, the first of which being that I am plain awkward,
As my amp is to be of the integrated variety in the typical sense the preamp in this case will be of the unbalanced type, and so if I can take the opertunity to use a OPA627 as a (buffer) buffer I would like to do so (still looking at how well that one would fair unity gain) the cost of these being more economical certainly in this case to use a single than a dual, Its more a case of taking advantage of a scenario, and simply being DIY the whole mod & con aspect is what one finds so appealling, call me obsessive compulsive (and call myself impurist) but I would feel like ive got an itch that I cant scratch if I left a channel of an opamp just conducting to ground.
I am not looking to have a chassis input for the UCD180
I would never power a power amp up with the interconnects unplugged anyway!!
I beleive using power and signal grounds correctly will have the same effect in this case with respect to ground currents.

again appreciate the input it does help indeed
Thank you!!!
 
#2,153
breizheau said:

- i soldered 3 wires for direct AOP supply
- i changed AOP for LM4562
...
Olivier
Click to expand...
Olivier, did you remove the CRDs or are they disconnected because of the external supply?

I still don't understand how to wire the CRDs to the positive side (cut traces?) so this is why I have not installed the LM4562 yet.

Guy
 
#2,154
Hi Guy,
Sorry but what is "CRD"...?🙄 I just removed the 2 SMD "transistors" as seen in the PDF file on Hypex site on soldered wires at the good place as described in the same file... It's not so difficult to do except that you shouldn't drink too much nice french wine the day before. Otherwise you will solder at the wrong side !!!!!😀 The + and - wires are easy but the GND needs to take care coze you solder it on a SMD resistor and the place is very very small....🙄
Believe me, i enjoy now my UCDs !:clown:
 
#2,155
So you removed the CRDs (Current Regulator Diodes) which bias one rail into class A operation. I guess I will just replace the opamp and remove the CRDs. Mmh maybe I need to add a wire to where the CRDs were to continue using the on-board 12V...

Thanks for the tip on the ground wire, I am not planning to use an outboard supply for now, but maybe the new regulator announced by Jan-Peter of Hypex.

Et ne pas boire de vin...sauf apres en ecoutant!
 
#2,157
Hi there !
another question maybe asked many many times but i cannot read all the previous pages.....:dead:

I want to make trigger outputs on my preamp main board to command the UCD blocks when i switch it on. What is the tension value to apply on the Hypex softstart and the "max time" ? And of course i want to know if it's possible to command the softstart with trigger !!!! 😀

Thanks....

Olivier
 
#2,158
bridging

Sorry to but in !
this question has been asked through a number of posts, so I am looking for clarification,
As the modules are half bridge you paralell the inputs and use both + for outputs ??
also using a 47n accross these to keep the operating f's the same ??

TAWN!

(ps how old is this thread!!!)
 
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