Well you can't believe what JP say's, he's biased, and he probably doesn't want to answer that kind of question, too much like marketing.
From all I've read, it doesn't rival anything, it is in a league of it's own.
Tact and the like were neat for their time but they've had their day.
True digital has been found to be inferior to self oscillating schemes, they never caught on, and most were lying about being true digital. Bruno made a high quality true digital amp and it doens't compete with this at all. You can likely expect better sound with this technology.
It seems, from what others have posted, UcD rivals the very best out there, class d aside. That's pretty good right?
From all I've read, it doesn't rival anything, it is in a league of it's own.
Tact and the like were neat for their time but they've had their day.
True digital has been found to be inferior to self oscillating schemes, they never caught on, and most were lying about being true digital. Bruno made a high quality true digital amp and it doens't compete with this at all. You can likely expect better sound with this technology.
It seems, from what others have posted, UcD rivals the very best out there, class d aside. That's pretty good right?
Re: UCD400 with AD8620 or not
Hello Marco,
In both cases there is a buffer. In one case it is an AD8620, in the other (standard) case an OPA2134 I think. Some people consider the AD8620 to be more high-end than the OPA2134. I don't know, have not heard a UcD400 yet. I now own UcD180 modules that perform very well, they use NE5532 opamps (or NE5534??).
Best regards
Gertjan
mevangel said:
Hello Marco,
In both cases there is a buffer. In one case it is an AD8620, in the other (standard) case an OPA2134 I think. Some people consider the AD8620 to be more high-end than the OPA2134. I don't know, have not heard a UcD400 yet. I now own UcD180 modules that perform very well, they use NE5532 opamps (or NE5534??).
Best regards
Gertjan
Two questions
Question n°1:
How does the UCD400 behave when loaded with a speaker whose impedance goes down to 2 ohms?
Question n°2:
Is it possible to attach the T-shape heatsinks of two UCD400 modules to a single chassis without using insulators (i.e. the two heatsinks are electrically connected) ?
Regards.
Marco
Question n°1:
How does the UCD400 behave when loaded with a speaker whose impedance goes down to 2 ohms?
Question n°2:
Is it possible to attach the T-shape heatsinks of two UCD400 modules to a single chassis without using insulators (i.e. the two heatsinks are electrically connected) ?
Regards.
Marco
Hi,
First question: Hypex will be able to deliver new stock in about two weeks I heard. This will be improved 400's. They will have no trouble with 2 Ohms. How the originals did I don't know, but the difference shouldn't be too big, so I think they do allright also.
Second question: Yes, no problem.
Frans
First question: Hypex will be able to deliver new stock in about two weeks I heard. This will be improved 400's. They will have no trouble with 2 Ohms. How the originals did I don't know, but the difference shouldn't be too big, so I think they do allright also.
Second question: Yes, no problem.
Frans
Hello,
I'm new here, just wanted to say thanks, I've read through most of this amazing thread, took me hours, but learnt SO much.
I'm no DIY-experienced guy, but got very interested in the UcD modules.
My goal is to drive two B&W Nautilus 804 speakers with Ucd400 modules, these may become new series 804S speakers later - for those whom are not familiar with these speakers, they are rated 200W @ 8 ohms, but have some nasty dips to 3.3 ohms - new models even to 3. As nice sounding as they are, they can't be driver with normal priced Class AB SS amps. So... I want to try my luck with Class D.
If I'm pleased, I'll build a second unit with 3/5 channels to complete a HT setup.
Here's some questions that I've compiled, for which I could not find a conclusive answer in this thread, please bear with me, and if some things are off-topic, feel free to reply in a PM.
I'm living in Belgium, Europe, 230/240V AC:
* Did anyone *alter* an existing Class A/B amp? I've opened my Yamaha DSP-A2 after learning about amps here, and found the "rails" for the main channels (and 2 huge 22.000uF caps @ 73V...), and also the "Pre-out"/"main in" bridge for L and R. So I could just use the modules in there if the voltage is right. (If a class AB amp is not driven, does it consume a lot of power? Because I can't disconnect the "old" channels) - i'll inform you on the voltage soon. VA rating for the transformer, NO idea, but it's *HUGE*
If the above is a no-go, I have these questions:
* Transformer size: I would like to go dual mono but am not sure yet? Along the way I've read that larger transformers are suggested for 4 ohm loads. Given that these are 8 ohm speakers with dips into 3.3 in the bass region, would 500VA per channel be enough or should I look into 800VA/1000VA? What if I choose 1 toroidal for the 2 channels?
* Caps: Caps uF should also be chosen wisely if I understand the thread correctly - too small is of course a no-no, but too large creates rush-in problems and sound alterations. Is 10.000 uF per rail enough/too much/too little for dual mono? Again, what if I have just one transformer? 63V of 80V caps?
* Bridge rectifier (if this is the right term?): I know these can be bought ready made, but don't understand the "ratings" - Is current the only spec to check, or do I need to watch out for their voltage specs? Am I right to choose at least 20A per channel?
* Bridge rectifier: I still don't understand why some designs have caps in parallel over the diodes - is there a laymans way to explain the need/lack of need for those?
* Slow-start: absolutely nescessary?
* Is there a click or discharge into the speakers when turning the UcD's on? How to remedy this? Slow start relay @ the speaker terminals?
* Should I worry about DC offset?
Thanks a million!
I'm new here, just wanted to say thanks, I've read through most of this amazing thread, took me hours, but learnt SO much.
I'm no DIY-experienced guy, but got very interested in the UcD modules.
My goal is to drive two B&W Nautilus 804 speakers with Ucd400 modules, these may become new series 804S speakers later - for those whom are not familiar with these speakers, they are rated 200W @ 8 ohms, but have some nasty dips to 3.3 ohms - new models even to 3. As nice sounding as they are, they can't be driver with normal priced Class AB SS amps. So... I want to try my luck with Class D.
If I'm pleased, I'll build a second unit with 3/5 channels to complete a HT setup.
Here's some questions that I've compiled, for which I could not find a conclusive answer in this thread, please bear with me, and if some things are off-topic, feel free to reply in a PM.
I'm living in Belgium, Europe, 230/240V AC:
* Did anyone *alter* an existing Class A/B amp? I've opened my Yamaha DSP-A2 after learning about amps here, and found the "rails" for the main channels (and 2 huge 22.000uF caps @ 73V...), and also the "Pre-out"/"main in" bridge for L and R. So I could just use the modules in there if the voltage is right. (If a class AB amp is not driven, does it consume a lot of power? Because I can't disconnect the "old" channels) - i'll inform you on the voltage soon. VA rating for the transformer, NO idea, but it's *HUGE*
If the above is a no-go, I have these questions:
* Transformer size: I would like to go dual mono but am not sure yet? Along the way I've read that larger transformers are suggested for 4 ohm loads. Given that these are 8 ohm speakers with dips into 3.3 in the bass region, would 500VA per channel be enough or should I look into 800VA/1000VA? What if I choose 1 toroidal for the 2 channels?
* Caps: Caps uF should also be chosen wisely if I understand the thread correctly - too small is of course a no-no, but too large creates rush-in problems and sound alterations. Is 10.000 uF per rail enough/too much/too little for dual mono? Again, what if I have just one transformer? 63V of 80V caps?
* Bridge rectifier (if this is the right term?): I know these can be bought ready made, but don't understand the "ratings" - Is current the only spec to check, or do I need to watch out for their voltage specs? Am I right to choose at least 20A per channel?
* Bridge rectifier: I still don't understand why some designs have caps in parallel over the diodes - is there a laymans way to explain the need/lack of need for those?
* Slow-start: absolutely nescessary?
* Is there a click or discharge into the speakers when turning the UcD's on? How to remedy this? Slow start relay @ the speaker terminals?
* Should I worry about DC offset?
Thanks a million!
Yves, I will try to answer all your questions;
Is possible, but perhaps it's smarter to build a complete new amplifier case. However watch the recommend voltage specs, 60-63V. Don't forget your are using a nice sounding amplifiermodule so it is wise to spend some more time to make the product also looking ok.
This is no problem, when you ask to much current the starts to limit the maximum current. We have done some tests with a load of 1 ohm, and the THD stays nice below 0.05%
Is possible, but perhaps it's smarter to build a complete new amplifier case. However watch the recommend voltage specs, 60-63V. Don't forget your are using a nice sounding amplifiermodule so it is wise to spend some more time to make the product also looking ok.
500VA is enough for every channel, it's also no problem at all to power up two UcD400 on one 500VA transformer. Or do you like to use your amps for partys
It depends on the powersupply voltage, it's save to stay -10% below the rated voltage of the capacitor.
* Bridge rectifier (if this is the right term?): I know these can be bought ready made, but don't understand the "ratings" - Is current the only spec to check, or do I need to watch out for their voltage specs? Am I right to choose at least 20A per channel?Fast recovery didoes or standard rectifiers with 100nF caps in parallel with the diodes. We use for a 160VA transformer KBU8J and for the 500VA transformer a KBPC3502.
The caps are for removing the switching noise of the recifiers when the go off.
Transformers of 500VA like a soft start (or your fuse actually like this
No, the UcD modules switchs ON or OFF with no thumps or bumps (or whatever)
The new modules are AC coupled so you don't have to worry about DC.
Good luck!
Jan-Peter
OK I just did some measurements on the receiver:
On the "rails" behind the huge caps I measure +/- 54.5 volts. This is the power supply for 5 class AB amps that Yamaha rates at 90W/channel (right...)
There is also a secondary AC 45v circuit feeding 2 additional amps (these are the front effects on the Yamaha's, 20W/channel)
I've downloaded the schematics of the larger brother of the DSP-A2, the DSP-AX1, and there's something strange there: (this is a higher powered machines, so measurements are different)
I've included the schematics. There is a bridge rectifier D701 and to the right, 2 caps 27000uF/71V.
I've measured the A2 at -B1, +B1 and G
What I do not understand is why the outputs of D702 join the outputs of D701 before the caps? I can't tell in the "real" A2 if this is also the case.
It's like D702 and D703 are secondary windings (with 703 feeding the 2 smaller amps) and they just added 702 to 701 - is this bad japanese design or am I misinterpreting the schematics?
Anyway... 45.5v should be very nice for the 400UcD's, no?
If I only could find the VA rating on the transformer... but if it is beefy enough for 5x90W in AB it should do for 3x90W and 2x200 class-D? (since D is more effective?) - the 2x90 will be idling, I don't want to disconnect them.
The 3 times 90W are never used fully, it's rear channels (into 4 ohms but highpass 80hz) and a centre speaker at 8 ohms (4.4 minimum)
Yves
On the "rails" behind the huge caps I measure +/- 54.5 volts. This is the power supply for 5 class AB amps that Yamaha rates at 90W/channel (right...)
There is also a secondary AC 45v circuit feeding 2 additional amps (these are the front effects on the Yamaha's, 20W/channel)
I've downloaded the schematics of the larger brother of the DSP-A2, the DSP-AX1, and there's something strange there: (this is a higher powered machines, so measurements are different)
I've included the schematics. There is a bridge rectifier D701 and to the right, 2 caps 27000uF/71V.
I've measured the A2 at -B1, +B1 and G
What I do not understand is why the outputs of D702 join the outputs of D701 before the caps? I can't tell in the "real" A2 if this is also the case.
It's like D702 and D703 are secondary windings (with 703 feeding the 2 smaller amps) and they just added 702 to 701 - is this bad japanese design or am I misinterpreting the schematics?
Anyway... 45.5v should be very nice for the 400UcD's, no?
If I only could find the VA rating on the transformer... but if it is beefy enough for 5x90W in AB it should do for 3x90W and 2x200 class-D? (since D is more effective?) - the 2x90 will be idling, I don't want to disconnect them.
The 3 times 90W are never used fully, it's rear channels (into 4 ohms but highpass 80hz) and a centre speaker at 8 ohms (4.4 minimum)
Yves
Attachments
Well, the only thing I intend to tap is the supply.
The unit has pre-outs which I can lead back to the UcD signal input, and I would add 2 speaker connections on the back plate of the Yamaha as output.
I'm not touching the existing circuitry, just "piggy-back" the power supply.
Since I wont be using the 2 existing L/R channels I don't see a problem.
I even found space on the heatsink
Yves
The unit has pre-outs which I can lead back to the UcD signal input, and I would add 2 speaker connections on the back plate of the Yamaha as output.
I'm not touching the existing circuitry, just "piggy-back" the power supply.
Since I wont be using the 2 existing L/R channels I don't see a problem.
I even found space on the heatsink
Yves