We do not have problems with HF crosstalks or heterodyne tones, even not this customer with his 5 channels UcD.....
http://www.diyaudio.com/forums/showthread.php?postid=743481#post743481
Jan-Peter
JP, did I say you had problems with HF crosstalks??? Its the utter satisfaction of having the maximum width/depth/clarity of the soundstage that counts. Ofcourse a 5 channel UCD may sound ok but for me ok would not be satisfying enough.......sorry.Jan-Peter said:
I never get any hum or crosstalk issues with my multichannel builds. I've twisted both power and speaker outputs on most but here is one we did where my tech failed to twist any of them. I'm playing it right now and it's audibly not any different than the others with a casual listen.
I'd like to try the 0.3 ohm resistor on the power supply though. I've not tried that yet and I'm curious as to if it's audible.
I'd like to try the 0.3 ohm resistor on the power supply though. I've not tried that yet and I'm curious as to if it's audible.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
Kevin,
At the risk of asking you a commercial secret of some sorts... 😀
How do you manage to install unbalanced and balanced inputs on your amps without a switch of some sorts?
Thanks
At the risk of asking you a commercial secret of some sorts... 😀
How do you manage to install unbalanced and balanced inputs on your amps without a switch of some sorts?
Thanks
Ha! No secret. The balanced ones on this particular amplifier are nothing other than an adaptor. Everything you plug into it is unbalanced in this configuration.
We build them all custom so if someone wants a switch they get a switch, if they want only unbalanced we give them that choice.
We build them all custom so if someone wants a switch they get a switch, if they want only unbalanced we give them that choice.
Kevin Haskins said:
Its not about having issues with humm or crosstalk, its about optimizing this. Using 1 double power rail f.i. must have consequences for the LF+HF crosstalk. Also wire layout, mains earthing??????? If you have no problem with this and accept it like it is thats OK for you than. The housing is very nice BTW.
Hi,
So I untwisted my output wires and tried moving them and as close to the transformer as I could, even having the speaker cable parallel to the mains for at least a foot.
No audible hum or tone was induced, the existing faint hiss heard with the ear right next to the tweater merely varied slightly when seperating the speaker wires from one another.
Twisting them again I found the hiss was simply more uniform, totally immune to movement (you can't seperate twisted wires).
That's important for when you crank it up and get into higher SPL that will make your wires dance around. Untwisted that wire movement will be audible, twisted it won't.
So this is a mono block setup, all wires are unshielded, however my toroid has magnetic shielding and electrostatic screening, I hope it explains why moving the wires around the transformer didn't result in any induced noise.
While I feel twisting the wires is simply a proper build technique and cheap to employ, I think the nature of the UCD module renders it robust to induced noise already, but still, why not baby them they're worth it.
Regards,
Chris
So I untwisted my output wires and tried moving them and as close to the transformer as I could, even having the speaker cable parallel to the mains for at least a foot.
No audible hum or tone was induced, the existing faint hiss heard with the ear right next to the tweater merely varied slightly when seperating the speaker wires from one another.
Twisting them again I found the hiss was simply more uniform, totally immune to movement (you can't seperate twisted wires).
That's important for when you crank it up and get into higher SPL that will make your wires dance around. Untwisted that wire movement will be audible, twisted it won't.
So this is a mono block setup, all wires are unshielded, however my toroid has magnetic shielding and electrostatic screening, I hope it explains why moving the wires around the transformer didn't result in any induced noise.
While I feel twisting the wires is simply a proper build technique and cheap to employ, I think the nature of the UCD module renders it robust to induced noise already, but still, why not baby them they're worth it.
Regards,
Chris
Passive or active preamp ?
Hi,
I am thinking about building stereo amp with ucd180 and ad8620 input buffer.
Can i use a passive preamp with it, or would you advice one active preamp, if so, than can anybody advice some good solution (some links?) with for example opa627 ?
Cheers, sinski
Hi,
I am thinking about building stereo amp with ucd180 and ad8620 input buffer.
Can i use a passive preamp with it, or would you advice one active preamp, if so, than can anybody advice some good solution (some links?) with for example opa627 ?
Cheers, sinski
Re: Passive or active preamp ?
You can use passive but may want to compensate for gain within the module that way, just changing one resistor value.
I'm using an active output which is the audiodock from the 1820M sound card.... gives you all the processing toys with true balanced i/o, real high end sound. They're drivers aren't yet where they need to be. You could look into other semi-pro cards for balanced i/o too. Mine cost me 500$, which I think is alot for a sound card, but as the center of a high end home theatre system with high dac's, good output op amps, all the bells and whistles, more than pays itself off with all the junk it replaces.
Regards,
Chris
sinski said:
You can use passive but may want to compensate for gain within the module that way, just changing one resistor value.
I'm using an active output which is the audiodock from the 1820M sound card.... gives you all the processing toys with true balanced i/o, real high end sound. They're drivers aren't yet where they need to be. You could look into other semi-pro cards for balanced i/o too. Mine cost me 500$, which I think is alot for a sound card, but as the center of a high end home theatre system with high dac's, good output op amps, all the bells and whistles, more than pays itself off with all the junk it replaces.
Regards,
Chris
Re: Re: Passive or active preamp ?
Hi Chris,
I want to connect to the output of the CD Player and will use probably 10k Log. What resistor should i change, if there is not enough gain, and how big it should be ?
Regards, Tomek
classd4sure said:
Hi Chris,
I want to connect to the output of the CD Player and will use probably 10k Log. What resistor should i change, if there is not enough gain, and how big it should be ?
Regards, Tomek
Cabinet cooling and ventilation slots
I will make new cabinet to my 4-ch UCD180
Internal measures are WxHxD 420x85x320mm. UCD:s installed uppright position (heatsink bolted to cabinet bottom plate.
Do i needed to drill ventilation slots to cabinet? And if yes, how much holes (area) is needed?
Reason why i ask that cabinet i have is made from 4mm aluminum and i do not want to dril much holes if not necessary.
PS. I will also install Velleman K4700 DC-protection modules to power-supply line and plan to use separate supply for UCD input buffer http://www.lcaudio.com/index.php?page=69.
I will make new cabinet to my 4-ch UCD180
Internal measures are WxHxD 420x85x320mm. UCD:s installed uppright position (heatsink bolted to cabinet bottom plate.
Do i needed to drill ventilation slots to cabinet? And if yes, how much holes (area) is needed?
Reason why i ask that cabinet i have is made from 4mm aluminum and i do not want to dril much holes if not necessary.
PS. I will also install Velleman K4700 DC-protection modules to power-supply line and plan to use separate supply for UCD input buffer http://www.lcaudio.com/index.php?page=69.
Hi,
I'm about to try floating my center tap node, see if it helps out with some ~120Hz hum I notice when my inputs aren't left floating.
To that end, what to do with the static screen green/yellow ground wire:
1. Connect to center tap, probably not
2. Let it float, and just enjoy the added isolation
3. Leave it at the star point and let it pollute it.
Also, I've found it's not the brightest of ideas to invert the phase of one module when being driven single ended. The inverted module has 10X the 120Hz hum. Nearly indaudible on the other, and becomes just as nearly indaudible by not inverting the phase.
Perhaps that's best left as an option strickly for balanced inputs, or should be left switchable along with the inputs.
I get some mains pollution /crackle/fzzzzzzzt feeding through to my speakers at times, I can induce it at will by playing with fans/switches, so some thoughts to the above would be useful to me.
I don't plan on going with a center tap arrangment in the final build, but I'd like this ironed out all the same, any thoughts appreciated.
Cheers,
Chris
I'm about to try floating my center tap node, see if it helps out with some ~120Hz hum I notice when my inputs aren't left floating.
To that end, what to do with the static screen green/yellow ground wire:
1. Connect to center tap, probably not
2. Let it float, and just enjoy the added isolation
3. Leave it at the star point and let it pollute it.
Also, I've found it's not the brightest of ideas to invert the phase of one module when being driven single ended. The inverted module has 10X the 120Hz hum. Nearly indaudible on the other, and becomes just as nearly indaudible by not inverting the phase.
Perhaps that's best left as an option strickly for balanced inputs, or should be left switchable along with the inputs.
I get some mains pollution /crackle/fzzzzzzzt feeding through to my speakers at times, I can induce it at will by playing with fans/switches, so some thoughts to the above would be useful to me.
I don't plan on going with a center tap arrangment in the final build, but I'd like this ironed out all the same, any thoughts appreciated.
Cheers,
Chris
classd4sure said:
Chris.
Mine stopped humming (50 or 100hz) and crackle/fzzzzzzzt'ing when I lifted the centertab. I'm running "floating" with absolut no hum or hiss - what so ever.
See http://www.frequence.dk/sites/avr300-amp.htm (text encrypted in Danish)
/avr300
Hi,
Yep makes sense. Any idea on the static shielding ground wire? I can try it either way I suppose, I'll let you know shortly.
Thanks,
Chris
Yep makes sense. Any idea on the static shielding ground wire? I can try it either way I suppose, I'll let you know shortly.
Thanks,
Chris
avr300 said:
Well, Plitron bends you over for an extra 50% just for magnetic shielding (really not impressed with Plitron for that reason) to cover the cost of the paper work telling them to add a simple feature, so it was just a few extra to get the static shielding from there and seemed stupid not to.
From toroid.com
"If the transformer includes a static shield for noise reduction, it is important to note that this shield does not provide the transformer with Safety Ground but it working as a functional earth. When the shield is grounded, it attenuates the common mode noise and can reduce the leakage current from the primary to the secondary winding (please note that this leakage reduction is not the same as when measured Primary to Ground)."
I guess I'll try it either way and see.
Regards,
Chris
classd4sure said:
aggh, stupid me, can't read!
well, I don't have this kind of (modern) wires. As you can see I'm using EI cores, I'm an old timer. Like you said it, "polluting". I wouldn't connect it. Let it, and the music float.
/avr300
avr300 said:
Don't worry, half the time I can't spell.
Let me tell you what SUCKS..
having to leave town for a few weeks while leaving your pet amp project wounded.
I just cut the center tap away from the star point, and floated the static shield... BAD MOVE!!!!!!!!!
The modules cut off right after I enabled them.... uh oh.
65V positive rail and a ~35 volt negative rail.
Normally they're around 45 to 47.
Must be the shield. So I should either ground it, or leave it connected to the "center tap". Later I'll be going with the dual bridges/no center tap. So I hope the answer will be to connect it to ground, or maybe then it won't matter.... I guess I"ll have to wait awhile to find out.
Sigh,
Chris
classd4sure said:
Must be hard to leave. Have a nice trip.
The only time I saw pumping was when I tested with af BAD cd player, you might call it a DC player. 2V DC offset on the input and the UcD was pumping. Better mind your caps.
Let me hear the progres.
I have a question about a transformer for the UCD 180.
With a 2x30v transformer I should be getting about 105w/8 ohm ?
or do I need 2.31 or even 2x32v for that?
Regards,
Christian
With a 2x30v transformer I should be getting about 105w/8 ohm ?
or do I need 2.31 or even 2x32v for that?
Regards,
Christian