Re: Need your advice, folks...
Hi MIchael,
Yes, you can use modules of other makers. In fact I have been using power supplies from LCaudio, but other makers will be fine as well.
For UcD180 modules a transformer that gives 2x33V secondary is a good choice, it will give you about 45V after rectification. For the UcD400, you may want to go for a 2x40V secondary transformer, this would give you about 55V. In both cases, the LCaudio supply is OK since the elcaps on that supply are 63V types.
I guess most other supplies for power amps will use 63V elcaps. So other supplies will be OK as well.
Best regards
Gertjan
mlihl said:
Hi MIchael,
Yes, you can use modules of other makers. In fact I have been using power supplies from LCaudio, but other makers will be fine as well.
For UcD180 modules a transformer that gives 2x33V secondary is a good choice, it will give you about 45V after rectification. For the UcD400, you may want to go for a 2x40V secondary transformer, this would give you about 55V. In both cases, the LCaudio supply is OK since the elcaps on that supply are 63V types.
I guess most other supplies for power amps will use 63V elcaps. So other supplies will be OK as well.
Best regards
Gertjan
Jan-Peter,
Does this mean that, in comparison with the UCD180, there are no holes anymore on the PCB to solder some coupling caps if one should want to use another (higher offset) opamp, or are they just bridged with a piece of wire?
Maybe a silly question, but the input impedance of 100k, is this measured between noninverting and inverting input, or between any input and ground? In the second case, impedance measured between + and - should be 200k then?
BUT... my source has an unbalanced output, so is it mandatory to connect UCD-ground to preamp-signal ground? If yes, the inputimpedance will indeed be 100k.
The idea behind is, that I would like to use a higher offset amp, but I'll have to combine fire and water then: high inputimpedance needed, but low offset wanted. So reducing those 100k R's but not needing GND would still keep input Z high. Or am I totally wrong ???
Yves
Jan-Peter said:
Does this mean that, in comparison with the UCD180, there are no holes anymore on the PCB to solder some coupling caps if one should want to use another (higher offset) opamp, or are they just bridged with a piece of wire?
Maybe a silly question, but the input impedance of 100k, is this measured between noninverting and inverting input, or between any input and ground? In the second case, impedance measured between + and - should be 200k then?
BUT... my source has an unbalanced output, so is it mandatory to connect UCD-ground to preamp-signal ground? If yes, the inputimpedance will indeed be 100k.
The idea behind is, that I would like to use a higher offset amp, but I'll have to combine fire and water then: high inputimpedance needed, but low offset wanted. So reducing those 100k R's but not needing GND would still keep input Z high. Or am I totally wrong ???
Yves
Hi Gertjan,
Regarding 63V PSU caps for the UCD400:
Far as I know there's usually a rule of thumb of about 30% extra headroom on the PSU caps to be safe, I suppose because mains voltage can actually vary by alot more than 10%.
So the module shuts down at ~63 volts, the supply won't. Wouldn't it be better to have some extra margin on that? I've been looking at 80V caps for that reason.
Thanks
Regarding 63V PSU caps for the UCD400:
Far as I know there's usually a rule of thumb of about 30% extra headroom on the PSU caps to be safe, I suppose because mains voltage can actually vary by alot more than 10%.
So the module shuts down at ~63 volts, the supply won't. Wouldn't it be better to have some extra margin on that? I've been looking at 80V caps for that reason.
Thanks
classd4sure said:
Hi ClassD4sure,
Well, I think 63V caps with a nominal 55V suply should be OK, that is almost 15% margin. Where does the 30% rule of thumb come from? The caps on the UcD180 are rated at 50V, you need more than a 40V power supply to get the rated output power, so margin would be less than 20%. Maybe the caps have some margin built in as well? I`m nor an expert on stuff like that, maybe Bruno can tell you more.
Best regards
Gertjan
Hi,
I wish I could remember but.... that's probably the wrong way of doing it anyway.
Possibly a better way is, starting with the unloaded condition at 10% mains overvoltage worse case scenario, allow for the capacitors tolerance. if that's -10% +50%, then 10% extra would be required, if it's +-20%, then 20% would be required. I think that would be the minimalist approach, basically that leaves 63V rated caps out of the question if the transformer is selected to give 63Vdc worst case.
From what I've seen so far caps have a "surge" rating for which it can handle some extra voltage, for so many cycles of a certain period.
I'm not an expert either, I'm sure someone will correct me if I'm wrong.
For instance does the rated tolerances of the caps lend to the capacitance value of them or to the DC rating?
Ah, there's a lot of articles on them out there for me to find.... few coffee's and an afternoon required I've only begun researching them.
Thanks
I wish I could remember but.... that's probably the wrong way of doing it anyway.
Possibly a better way is, starting with the unloaded condition at 10% mains overvoltage worse case scenario, allow for the capacitors tolerance. if that's -10% +50%, then 10% extra would be required, if it's +-20%, then 20% would be required. I think that would be the minimalist approach, basically that leaves 63V rated caps out of the question if the transformer is selected to give 63Vdc worst case.
From what I've seen so far caps have a "surge" rating for which it can handle some extra voltage, for so many cycles of a certain period.
I'm not an expert either, I'm sure someone will correct me if I'm wrong.
For instance does the rated tolerances of the caps lend to the capacitance value of them or to the DC rating?
Ah, there's a lot of articles on them out there for me to find.... few coffee's and an afternoon required
I've only begun researching them. Thanks
UCD400 shopping list?
Hi folks,
I was browsing the Internet for a part list of items I need
to build an audiophile grade no-compromise UCD400
stereo amplifier with approx. 150-200W/8Ohms.
I live in a 230V country...
Can you comment on my list of items? Did I make any
mistakes? (I'm not an expert)
1.) Amp: 2 x UCD400 modules
2.) PSU (1 piece):
I would either go with LCAudio's (expensive) Virtual
4-pole 100.000uF supply at 315 Euro - is this overkill?
Alternatively, I would get this PSU from Schuro:
http://www.schuro.de/preisl-nte10-63tnet.htm
(supports max. 2x35V transformers, 4x10.000uF Caps...)
Which one would you take? I want to have enough
reserves, quality comes first.
3.) Transformers: First question - do I need 1 or 2
transfomers for a stereo amp?
For LCAudio I am thinking of this transformer:
2 x 40 V, 600VA (http://www.schuro.de/preisl-v-rkt-ms-sw.htm)
For the Schuro supply, I would take this type:
2 x 35 V, 600VA (http://www.schuro.de/preisl-v-rkt-ms-sw.htm)
Did I make any mistakes in this setup or would you suggest
any changes? I plan to order my UCDs this week.
Thanks for your help, guys!
Michael
Hi folks,
I was browsing the Internet for a part list of items I need
to build an audiophile grade no-compromise UCD400
stereo amplifier with approx. 150-200W/8Ohms.
I live in a 230V country...
Can you comment on my list of items? Did I make any
mistakes? (I'm not an expert)
1.) Amp: 2 x UCD400 modules
2.) PSU (1 piece):
I would either go with LCAudio's (expensive) Virtual
4-pole 100.000uF supply at 315 Euro - is this overkill?
Alternatively, I would get this PSU from Schuro:
http://www.schuro.de/preisl-nte10-63tnet.htm
(supports max. 2x35V transformers, 4x10.000uF Caps...)
Which one would you take? I want to have enough
reserves, quality comes first.
3.) Transformers: First question - do I need 1 or 2
transfomers for a stereo amp?
For LCAudio I am thinking of this transformer:
2 x 40 V, 600VA (http://www.schuro.de/preisl-v-rkt-ms-sw.htm)
For the Schuro supply, I would take this type:
2 x 35 V, 600VA (http://www.schuro.de/preisl-v-rkt-ms-sw.htm)
Did I make any mistakes in this setup or would you suggest
any changes? I plan to order my UCDs this week.
Thanks for your help, guys!
Michael
Please when you use the NE5532, don't remove the coupling caps.
To tell you the truth, I don't know yet. We have currently two designs on the workbench, one bridged version and a single ended. Not yet decided what will be the UcD700 or even UcD1000
.....hm, am I impressed?
The proof of the pudding is the eating, I would see try to compaire the amps acoustically
Indeed there are no holes anymore, it's just removed. The 100K is measured between input or none-inverting to ground, indeed impedance between + and - is 200K. No when you correctly hooke it up, asymetrically, you will have 200K inputimpedance. The cinch has an hot output and ground. Connect the +input of the UcD to the hot cinch output, connect the -input of the UcD to the ground of the cinch. Connect also the ground of the Ucd to this ground at the side of the cinch.
When you wants to use a higher offset opamp, you can cut the coppertraces and add a coupling cap. Or create a DC-offset adjustment to inject several DC mV at the input just as you do to correct the DC adjustment with a normal analog amplifier.
Powersupply;
Our recommondation will be 63VDC-10%. When you order a transformer ask if the voltage of the transformer is in unloaded or loaded setup. This two voltage can have a difference of 10% (or even more)
Regards,
Jan-Peter
www.hypex.nl
PS. we have a 500VA transformer what gives 57VDC, pefect for the UcD400. And a set of BCC 10.000uF / 63V capacitors together with a 35A bridge rectifier. (KBPC3502) Please mail us for prices.
DSP_Geek said:
And FYI my transformer with rated 35Vac secondaries
measures 53Vdc after rectification.
I think classd4sure has a similar over voltage supply that I have
so you could probably expect a similiar output. Scaling this
with a 38Vac secondary I guess you would get 57.5Vdc.
So I guess it's a choice of slightly more than the 10% safety or
slightly less.
Hi Jan-Peter,
I admire your product, the way you make it accessible to the diy-er, and the way you are so forthcoming with honest information about it. Sometimes I wonder how the some of the marketing guys in audio can sleep at night (present e-company excluded, of course). You are very lucky to have Bruno on your team, too. ('nuf schmoozing - on to the questions)
With an unregulated supply the UcD amps will face occasional line surges. How are they designed to ride these out safely? I would assume that you depend on the surge capability of the capacitors (the caps start leaking more and more and dissipating power as the over voltage goes up, but they can absorb a certain amount of energy for a short time before going into a thermal run away). I would also assume that the mosfets quit switching to protect themselves (thereby doubling the voltage withstand capability of the totem pole). But what of the other circuitry? Is there a driver IC that must withstand the over voltage (if so, what is its rating)? Probably most of the circuitry is supplied by a series pass regulator, so over voltage would not be a direct concern there, but what is the rating of the (assumed) series pass element?
Regards -- analog(spiceman) -
We leave the protection for this failures to the designer of the power supply
An easy solution would be to use 275Vrms VDR, or the half voltage for US systems. The voltage rating of the 470uF capacitors is 63V (this is the reason of the abs. max. of 63V). The caps can stand a +15% surge voltage. The small 10uF caps are rated for 100V, I prefer to take a higher voltage rating by smal decoupling caps. The used Power Fets have a rating of 150V. Besides this we don't use any regulators only a Zener and a T0-220 Powerdarlington for the +15V/-15V. These powerdarlingtons have a VCE rating of 100V.BTW, we don't use an IC Driver for the Powerfets, we use a quite complex Full Discrete Fet Driver.....
Regards,
Jan-Peter
www.hypex.nl
nickywicky said:
Hi, yes that's the same conclusion I came up with exactly. So I recalculated without fudging any #'s this time.
The "1.2" 20% error I used included a bit of a fudge because mains voltage here is rated at 120/240. I think it safe to assume when I measure 122 it's overvoltage well within spec.
I'm looking at Plitron transformers since they aren't very far from me, only a day's shipping and not cross border.
So from what I can see on their website, all ratings are given for a fully loaded condidition, and regulation factor is given as 4%
Using 120V, 10% safety margin and 4% load regulation, and a final value goal of 64.4, I get 37.2.
So calculating for 38Vac secondaries with the new error percentage (non fudged) I wind up with 63.6 (worst possible case)-1.4 for the bridge rectifier, =62.2.
So once again that's including a full 10% mains overvoltage +idle condition (provided their stated regulation factor isn't a load in itself).
So I think 38Vac secondaries in my case are right on target and will chose those.
As far as the caps are concerned, do they not degrade a bit each time the surge capability is used? If that's the case I'd consider changing those 470uF caps first thing, and won't be using 63Volts in the power supply either.
Thanks
Regarding the capacitor comments in my previous post,
We know they do degrade with overvoltage, and in the way that analogspiceman was so kind as to explain.
This is seemingly an immediate, possibly permanent degradation.
Are we to believe that while 63Volt caps got the job done for the ucd180, those same 63volt caps will be sufficient for the ucd400, when there is now a zero margin of safety on them? This would have to be the main reason upgrading them to ~75 volts is "under consideration".
Makes me nervous..
We know they do degrade with overvoltage, and in the way that analogspiceman was so kind as to explain.
This is seemingly an immediate, possibly permanent degradation.
Are we to believe that while 63Volt caps got the job done for the ucd180, those same 63volt caps will be sufficient for the ucd400, when there is now a zero margin of safety on them? This would have to be the main reason upgrading them to ~75 volts is "under consideration".
Makes me nervous..
Jan-Peter said:
To tell you the truth, I don't know yet. We have currently two designs on the workbench, one bridged version and a single ended. Not yet decided what will be the UcD700 or even UcD1000
[....]
For what it's worth, I'd vastly prefer a single ended UcD700 as I can readily get my hands on a +- 80 volt supply.
Thanks,
Francois.
Voltage of capacitors
We decided today to increase the voltage of the 470uF capacitors from 63V to 100V.
It's was not easy to find a good source with low (25mm) 470uF/100V caps.........
Regards,
Jan-Peter
www.hypex.nl
We decided today to increase the voltage of the 470uF capacitors from 63V to 100V.
It's was not easy to find a good source with low (25mm) 470uF/100V caps.........
Regards,
Jan-Peter
www.hypex.nl