UCD180 questions

[teflon1]

Ronny,

I fear you've truly an aversion to the facts. Clearly this discussion pertains to ucd. Going back years prior to that is, to be generous, irrelevant, non sequitur. It also doesn't leave you with any less of a common impedance concern, or any other anomaly one is likely to experience by wiring the shield directly to signal reference, which as a rule, you never do! Hypex has an app note which demonstrates appropriate methods, you should read it, this is not a question of preference.

As a manufacturer using OEM modules I find it unlikely you'd be concerned with the savings of not having the HXR regulators, since OEM modules don't come with them anyway. Also please note my comments in no way reflect upon your preference for a tube hybrid approach, but rather the method used to employ it, which from your first picture that you keep referring others to, can be greatly improved.

Your facts once again fall short of reality. OEM versions do include an input stage, along with the additional means to bypass them. They may not easily be available for purchase, but you don't need any special credentials to download the datasheet and see that. A true OEM should be skilled enough to put that feature to use without greatly compromising it. For example the edge connector allows for a certain configuration that wouldn't compromise RF performance even when using an offboard input stage. Certainly in their wisdom they'd also include any necessities that bypassing the onboard input stage may have curtailed, at least one would hope.

Soundcheck, I think the proper way to make the input stage a stable unity gain buffer is to short the feedback resistors, and remove the gain setting resistor, leaving it open. The other alternative discussed may not have the kind of results you're after.

Johnny

[Koifarm]

Johnny, i just can tell you try and listen. And publish here your experience.
Others can learn from that experience.

I used a long time the "ST" modules. And i like them after modifying as good as the "HG" modules. With the tubebuffer they were perfect for me. My tubebuffer can drive impedance as low as 600 Ohm but is optimzed for 1k8 (lowest distortion).

I know al the application papers of hypex. But there are more ways to Rome.
Before you know with way you like most you have to try them all.

I tried for example 8 different tubebuffers with more than 5 types tubes, but one of the simplest tubebuffers i like the most.

If you happy to do it your way, that is great.
I do it my way.

Ronny

[soundcheck]

Hi folks.

I think Ronny is more then right on one point.

There is no opamp, which is not degrading the sound. So, I strongly believe
that if the source can cope with 1k8 amp input impedance and an overal gain of 4.5 is OK, this is the way to go.
I mean - If possible I would generally avoid any active element on the input. Tubes might have a nice sound signature, but are they lossless? No way!

The open question to me is still how to pass the input by on the UCD180HG module (by keeping it somwhat revertable) . What would be the best access point?

Cheers

[Koifarm]

Soundcheck, make a picture from above and i will try to point out the best access points.

Ronny

[Hansms]

Must there be a LED burning when the ucd180HG is stiwched on?
D6 is that a LED? on the ucd180hg print?

I have very low level sound, i put my ear to the speaker. But the volume will not go up.

What do i wrong, i Put the wires as in the drawing from hypes.
Also i connect the ON wires to GND,

is the UCD180HG broken?

thanks for any help

gr,
hans.

[kepa1]

Hello,

I'm going to use my pair of UCD180 (standard) for a friend's wedding and would like to have recommendations regarding their use in that kind of environment : playing loud for a long time.
Though Hypex claim a "public adress application", they are only 100 watts (in 8ohms) and that's not so much even with 95db bass speakers.

Any input (other that "don't do that, you fool")?

[maxlorenz]

Allow for enough ventilation.

Have a good time.
M

[kepa1]

Thank you Max!

My UCDs are built in a bass reflex enclosure, so there should be some air cooling.

[kepa1]

I have another question.
My source can reach +22db balanced (DCX2496), so does that mean that I need -25db of attenuation to avoid any problem (oscillation)?
Thank you

[NicMac]

Hello all Hypex'ers,

I'm the happy owner of a DIY power amp based on UcD180HG HxR modules with a regulated power supply. I'm driving this amp directly from my DIY DAC (Buffalo 32S) with attenuation in the digital domain. I'm very satisfied with this combo but my tweaker genes tells me that maybe I can still improve......

I listen to music at modest levels and the combined gain in the DAC and amp is way higher than I actually need. I know I have different options including:
A) reducing the gain of the DAC I/V stage
B) reducing the gain of the UcD buffer stage
C) bypassing the buffer-stage of the UcD
Doing it by methods A and B is pretty straightforward, but as method C will reduce the number of active components in my signal path and remove coupling caps entirely, I have decided to follow this route.....

For comparison I will not be tweaking the UcD's modules I already have, but will get a pair of ST modules for the purpose. The DAC I have features balanced output with low DC offset (<1mV) and low output impedance (milliohms to a few ohms) so I believe that they should drive the UcD's just fine without the buffer stage (1K8?). As I'm using a regulated supply I think that supply pumping will not be an issue.....

So to get to the question: how do I actually wire this bypass on the UcD180ST modules the best way?
I have been going over pages and pages but I have not found detailed descriptions of how this is done. Could somebody please point me in the right direction?
Ideally I would like to use the signal connections on the ST modules for easy "swap" comparison between the bypassed ST and my "reference" HG/HxR.
I don't mind if the modding of the ST's will be irreversible.
All kind of advice would be very welcome!
Thanks,
Nic