UCD180 questions

[UrSv]

Got it. I will probably run them virgin at first but still making sure I understand...

Thanks

[ghemink]

Originally posted by Jan-Peter
Hi Charles,

I don't specially mean you, but you called mine small modules "quit sexy". So I was wondering how it is in real life

The connector we use is a copy of the Molex KK series, 2.54mm pinning. Indeed a good idee to offer several sets of different type of cables. We are currently developing a website where these modules can be orderd.

I am not an expert in how different electronic components do sound. For this we better wait till Bruno is back from his vacation. If you are shure about your filters/preamp having no DC I would simply remove the cap's and listen to a small piece of copper wire

In a way no cap is not such a problem, however a small DC input wll create a small plop in your loudspeaker. It is increadible how less DC voltage will create a hearible plop!


Regards,

Jan-Peter

www.hypex.nl

Hi Jan-Peter,

I will give it a try (with a straight wire) once I have my updated DEQX PDC with XLR outputs. I`m also thinking of moving the caps before the opamps. They can then be smaller because of the higher input impedance. Removing the caps between opamps and UCD module itself may give a bit more output offset voltage as the offset voltages of the opamps would be amplified by the UCD. I`ll do some checks with a voltmeter to see what output offset DC I`m getting with and without caps.

Best regards

Gertjan

[phase_accurate]

A good chance these modules do sound much different as other amplifiers

Having heard more than one switching amp so far I can imagine that this is indeed true ! All of them had one thing in common: They sound effortless like only generously dimensioned linear amps do usually !!


Regards

Charles

[Bruno Putzeys]

Hi,

What do people do when they are on holidays (Slovakia) and find a computer on their way? Check their mail... Goodness I must be becoming a communication addict.

I read through this thread and just like to add a few tidbits.

Pumping is dangerous only when it's constantly going one way. If you are amplifying a 10Hz signal, the power rails alternately pump, but the whole process doesn't run away. The 10000uF storage caps suggested by JP are moooore than sufficient even in an extreme case such as 10Hz. If only the audio signal were at issue, no AC coupling or pumping protection would be necessary.

It does become a problem when the output is DC because then one rail keeps going and going. Most audio sources are DC-free but some aren't. The last one I've had trouble with was a tube preamp with paper/oil output caps. Once more than about 200mV develops on the speaker output - zingo.

This is why it was decided to put coupling caps in the UcD180 modules. Newer versions will include the overvoltage protection so the user can safely experiment with removing the caps. With this protection present, the worst thing that can happen is that the amp periodically shuts down. Sonically it's always worthwhile to substitute the voltage protection for a coupling cap. I can assure you that a short sounds better than even a black gate cap.

On the 2134: It's a nice little amp with excellent price/performance, but it's not totally neutral. In its own way the 5532 is more neutral but less transparent. The result is that you can afford to have quite a lot of 5532s in the signal path before colouration becomes obvious.
Some audio engineers (not to name people like D. Self) use this fact to claim that the 5532 is "the perfect opamp" and that adherents of other chips are whiners. Such notions go a bit far for me though... I'm still stuck on my own discrete op amps (or did you think I only made class D amps out of discrete transistors).
If you have several active stages and you want to avoid the loss of transparency that goes with the 5532, I would suggest keeping several types of pin-compatible op-amps at hand and making a healthy mix. A similar story goes for capacitors btw.

On a lighter note: I once suggested to JP that he also use blue circuit boards (=blue solder resist) for consistency. Do you think I should pressure him?

[Jan-Peter]

Hello,

I promised a schematic for an overvoltage protection. Please look to attachment. This design is only for DIY, not for manufactures. Copyrights are by Hypex Electronics BV.

Regards,

Jan-Peter

www.hypex.nl

[classd4sure]

Hi,

Thanks for the overvoltage schemtic Jan. It's nice and simple.

You know I was thinking last night about the blue this and the anodized that.. I'm sure it looks good, and I'm sure the cost of which is past on to the consumer. I'm all for the highest of quality, but i'm against added cost for mere cosmetics which add nothing to quality. Once it's inside a box no one will ever know there's a nice blue heatsink or what color the solder mesh is..

The lower priced you're able to keep your modules the more people will be able buy them, and I've very little doubt the performance of this module can speak for itself.

Anyway, Just a thought I had.

Thanks again for the protection circuit.

Regards,
Chris

[ghemink]

Originally posted by classd4sure
Hi,

Thanks for the overvoltage schemtic Jan. It's nice and simple.

You know I was thinking last night about the blue this and the anodized that.. I'm sure it looks good, and I'm sure the cost of which is past on to the consumer. I'm all for the highest of quality, but i'm against added cost for mere cosmetics which add nothing to quality. Once it's inside a box no one will ever know there's a nice blue heatsink or what color the solder mesh is..

The lower priced you're able to keep your modules the more people will be able buy them, and I've very little doubt the performance of this module can speak for itself.

Anyway, Just a thought I had.

Thanks again for the protection circuit.

Regards,
Chris

Hi Jan-Peter, Chris,

I agree with Chris, don`t need to spend money on the cosmetics. That money should better be spend on the components itself. I`ll see what I do with the overprotection circuit. I assume that I can remove the coupling caps and put coupling caps in front of the opamps or replace the coupling caps with smaller caps for tweeter and midrange use.

A question for Bruno, does this power supply pumping already occur for such low DC levels (few hundred mV) at the output?

Another way to get rid off the power supply pumping issue would be to use two modules bridged. However if it is true that a few hundred mV at the output can cause power supply pumping, then that would not be a guarantee to avoid it.

Best regards

Gertjan

[ghemink]

Originally posted by Bruno Putzeys
Hi,

What do people do when they are on holidays (Slovakia) and find a computer on their way? Check their mail... Goodness I must be becoming a communication addict.

I read through this thread and just like to add a few tidbits.

Pumping is dangerous only when it's constantly going one way. If you are amplifying a 10Hz signal, the power rails alternately pump, but the whole process doesn't run away. The 10000uF storage caps suggested by JP are moooore than sufficient even in an extreme case such as 10Hz. If only the audio signal were at issue, no AC coupling or pumping protection would be necessary.

It does become a problem when the output is DC because then one rail keeps going and going. Most audio sources are DC-free but some aren't. The last one I've had trouble with was a tube preamp with paper/oil output caps. Once more than about 200mV develops on the speaker output - zingo.

This is why it was decided to put coupling caps in the UcD180 modules. Newer versions will include the overvoltage protection so the user can safely experiment with removing the caps. With this protection present, the worst thing that can happen is that the amp periodically shuts down. Sonically it's always worthwhile to substitute the voltage protection for a coupling cap. I can assure you that a short sounds better than even a black gate cap.

On the 2134: It's a nice little amp with excellent price/performance, but it's not totally neutral. In its own way the 5532 is more neutral but less transparent. The result is that you can afford to have quite a lot of 5532s in the signal path before colouration becomes obvious.
Some audio engineers (not to name people like D. Self) use this fact to claim that the 5532 is "the perfect opamp" and that adherents of other chips are whiners. Such notions go a bit far for me though... I'm still stuck on my own discrete op amps (or did you think I only made class D amps out of discrete transistors).
If you have several active stages and you want to avoid the loss of transparency that goes with the 5532, I would suggest keeping several types of pin-compatible op-amps at hand and making a healthy mix. A similar story goes for capacitors btw.

On a lighter note: I once suggested to JP that he also use blue circuit boards (=blue solder resist) for consistency. Do you think I should pressure him?

Hi Bruno,

Thanks for your reply during your vacation. I will keep the NE5532 in for the time being. I will experiment with the caps first. Maybe remove them later completely, don`t know that yet.

I have up to know only tried the amps on my passive speakers. The active speakers have higher resolution and will therefore better suitable to reveal differences in amps and caps etc.

In the active setup I plan to compare the UCD modules with the Tripath based Marantz 4 channel amp. I assume the UCD wins :-). Then I will later experiment with modding the UCD modules. Probably I`ll buy a couple more so that it is easier to compare modded and unmodded. Jan-Peter would have no objection against that experiment :-)

Best regards

Gertjan

[phase_accurate]

Supply pumping: The lower the frequency, the lower the current needed to make it happen, so the least current is needed for DC output.

I once used some active circuit to compensate for the pumping. The circuit was in fact a simplified class-d amp that was "driving" a short at it's output. To say it in simple words: It worked quite well but I wouldn't bother to attempt something like that again.

As an alternative a charge pump could be implemeted quite easily that balances the power lines. Or some sort of synchronous rectifier could be used in the PSU.

About the blue colour:
I don't think that it makes the whole thing more expensive. I assume that Jan-Peter gets those in large quantities from a manufacturer and the latter doesn't mind what coluor is used for anodising.
BTW: Wait until the first one builds an amp with transparent cover !

Regards

Charles

[IVX]

Jan-Peter,
seems that product line comes to the more power side. Do you plannes for some Super UcD?(extremely precision version by using fully discrete construction or audiophiles components etc, maybe lower power and upper cost as a fair sacrifice)