UCD180 questions

[FuriousD]

Now that you have a power amp with a differential input (and presumably a preamp with rca outputs) , make interconnects with an rca connector on the preamp side and a male xlr on the power amp side, using balanced cable. On the rca end, tie the cold lead and the shield together to ground. Wire the xlr end as appropriate:

Bruno,

Not sure that I'm reading this correctly, but are you actually advocating connecting Signal 0V to Chassis Earth???

I am in total agreement that interconnect cables should not be used to connect chassis Earths.

F.

[Bruno Putzeys]

Originally posted by Dave S
How does the amp respond to capacitive loads? I have seen 0.1uF maximum specified elsewhere although your spec states "load independant bandwidth". Are there any issues with stability into difficult loads?

The amplifier is already capacitively loaded - the output capacitor is 680nF. As long as what you're attaching is lower than this (order of magnitude) you're safe. Especially if you're using speaker cables. The impedance of even a short speaker cable is high enough to "decouple" the load from the amp.

I don't think you should worry.

[Bruno Putzeys]

Originally posted by FuriousD


Bruno,

Not sure that I'm reading this correctly, but are you actually advocating connecting Signal 0V to Chassis Earth???

I am in total agreement that interconnect cables should not be used to connect chassis Earths.

F.

In balanced connections, the chassis are connected through the cable. In unbalanced connections, this is not healthy (hum), so there you would have the audio ground floating with respect to chassis. Unfortunately, floating grounds are an EMI hazard (susceptibility, not emission). You then see folks adding small caps between chassis and signal ground at the input connectors in order to make an HF connection. In doing so they create a brilliant hf current loop inside the device between the internal "star" and all the connectors. Such contraptions make my stomach turn. With simple audio setups, one may have some sympathy for the seeming simplicity of unbalanced operation but once things get complicated they get ugly too.

Balanced audio equipment is normally not designed to have a floating ground (it is tied to chassis), simply because ground is not used as part of the signal. The sound quality advantage of correctly designed balanced connections is often underestimated (possibly due to the relative rarity of correctly designed ones).

Of course, some people do still use floating grounds combined with balanced wiring. Thus they invite EMI ingress problems. Their choice, not mine.

[Konrad]

Sometimes it's easier to ask than to check or simulate;

I can understand that the build upp on the psu can happen when there is some dc at the output. And that it will happen on the opposit supply. Caused by the conduction / current try to continue flowing in the output coil.
Serie diode with the outputs sorse side on positive psu and drain side on neg psu. will then (?) make the voltage at the coil conection go almost (useless)

But storing/losing some energy in a zobel ( R with series C) across each switching device it should bee more tolerant to dc ofsett ( energy stored/energy consumed) ie reverse conduction of energy redused by stored energy-losses, may bee difficoult for the full range of output. For a smal amount the losses is not so big either. The tolerance for dc I GUESS will bee higher without pumping. But has some drawbacks regarding zwitching and distortion. Somtimes in simulation i find the switching performance kind of better, the voltage at the switched side of coil do not swing to the opposit end when not conduckting. And the voltage feeding the coil have less ripple hence the output ripple/noise will also bee redused by the same amount.
Losses however.... a small compromise maybee ?


( No offence taken!)

On the UCD 400 pics there seem to bee a smal open space so that double outputs could bee monted, is it so? ( 8psc dvc of 8+8 Ohm [6.8 Ohm dc] for my bottom and i'm just starting to think about it.... By now my home made with a huge amount of output dewices is feeding them )
And is the UCD 400 available already?
Can it bee monted in a 1u h cabinett ie 38mm high no more?

[Bruno Putzeys]

Originally posted by Konrad
But storing/losing some energy in a zobel ( R with series C) across each switching device it should bee more tolerant to dc ofsett ( energy stored/energy consumed) ie reverse conduction of energy redused by stored energy-losses, may bee difficoult for the full range of output. For a smal amount the losses is not so big either. The tolerance for dc I GUESS will bee higher without pumping. But has some drawbacks regarding zwitching and distortion. Somtimes in simulation i find the switching performance kind of better, the voltage at the switched side of coil do not swing to the opposit end when not conduckting. And the voltage feeding the coil have less ripple hence the output ripple/noise will also bee redused by the same amount.
Losses however.... a small compromise maybee ?

What a complicated way of losing energy! Life's quite simple. If you have pumping, providing extra energy loss will reduce the problem. Whether you do this by making the snubbers heavier than necessary or by simply placing a ballast resistor across the power rails is not instrumental... Just try not to have DC at the output. Nobody needs DC at a speaker output anyway

Cheers,

Bruno

[Jan-Peter]

Konrad,

The UcD400 is in order by our PCB manufacture and assembler. In about 6 weeks (perhaps sooner?) we will have them on stock.

On the UCD 400 pics there seem to bee a smal open space so that double outputs could bee monted, is it so?

What do you mean with this question?

The connectors are as follows from left to right;
4 input connector
1 - +input
2 - ground
3 - -input
4 - amp_on

2 pin power connector
1 - power out hot
2 - power out cold

3 pin power connector
1 - +powersupply
2 - ground
3 - -powersupply

Indeed it can be mounted in 1 HE case

Regards,

Jan-Peter

www.hypex.nl

[peranders]

Originally posted by Jan-Peter


2 pin power connector
1 - power out hot
2 - power out cold

Is cold the same as ground (didn't you say somewhere that you had a half bridge?)?

[Jan-Peter]

Peranders,

Not exactly, we have a symmetrical feedback straight from the outputterminals. So the cold output is nearly ground


Regards,

Jan-Peter

www.hypex.nl

[Konrad]

On the UCD 400 pics there seem to bee a smal open space so that double outputs could bee monted, is it so?

I meant switching devices, but that is minor concern. To reform the Q i was intrested in the available current output.

So there is a chance for somthing spesial under the x-mas tree i guess.
if not il have to make somthing else.

Abt those losses, i dont actually mind where they are as long as the contribution to better performance is good. and not too big either

[Jan-Peter]

Konrad,

Ah more Powerfets? This will not be possible, because extra powerfets will increase the switching losses. And dergreaded the performance. Don't forget we are talking here about a switching amp who switchs at 450kHz and in about 20-50nS from zero to +60VDC. ( it can be even faster, I will check this tomorrow)

It's not a liniear amplifier

I don't know when you have Christmas ( ) but within 1 to 1.5 month we have the UcD400 on stock!

Regards,

Jan-Peter


www.hypex.nl