TerryG said:
FWIW, I've owned quite a few amps over the past two decades. The two best ones were a one-off, highly modified Stax DA-80, which the designer once owned and the other was a Music Reference RM-200. The UcD's that I now own are at least as good sounding as either of those amps. In my world, I do consider the UcD's world class.
classd4sure:
Well, it's very early in the game and I have to try hard to avoid "Proud Papa Syndrome", but I do believe my audio experience has just jumped several levels. About a week or so ago I finished a Tripath based amp and was somewhat dissapointed, at the time I was also considering picking up a Panny XR-70 mainly for the convenience it would provide in experimenting with active XO's this winter, but I decided to get the the UcD's instead. Smart Move 😀
Well, it's very early in the game and I have to try hard to avoid "Proud Papa Syndrome", but I do believe my audio experience has just jumped several levels. About a week or so ago I finished a Tripath based amp and was somewhat dissapointed, at the time I was also considering picking up a Panny XR-70 mainly for the convenience it would provide in experimenting with active XO's this winter, but I decided to get the the UcD's instead. Smart Move 😀
Hi,
Once again I've floated my PSU, this time with the T-networks.
I didn't like what I saw at first. Yet another offset... allow me to recap (no pun intended).
First I thought the static shield could be inducing noise into my star ground point, a reasonable assumption.
So I cut that wire. Stupid move, having left the modules connected for that test (zzzzz...).
A wicked rail imbalance occured. Don't ever float your static shield! It must be earthed.
So I earthed it again, and floated the rest of the supply. A two to three volt DC imbalance occured. Not even a 1/10 as disgusting as before, but all the same, ugly.
That was with a single rectifier /center tap setup.
Next move, I upgrade. Dual FRED bridge rectifiers, 68 amp/600V PIV, and BHC T networks. That sounded nice. I had them grounded on the input side. All was well.
Next step, Mr. Stubborn decides to experiment further.
I cut the static shield wire again.... no, just kidding, that really has to be grounded.
I did cut the ground from the input side of the T-networks/rectifiers though, and soldered some new wires in so that each secondary/bridge r. /cap is fully isolated from one another at the input side, and fully floating. Disconnected the modules from the supply, popped the safety glasses on, powered it up and took a measurement. About a diode's drop worth of offset... Didn't like that, but it's not so ugly that you wouldn't tell your friends about it.
So I discharged the caps, plugged the modules in, powered it up and gave it a listen. Then I took a measurement. With the load of the modules the rails were dead equal. AAhhh, nice.
How did it sound? Expanded X10! Envelopping. The highs finally became ultra disctint, with no edge or harshness, just smooth and crystal clear. So while I may not have the double isolation transformer, and I doubt many of us do since it was only recommended just recently, I'm afraid I can't go back. At least the static shield to ground offers some measure of safety, I'll soon have myself convinced that's good enough 🙂
I thought I'd unplug my input cables and see how that little bit of hiss has changed, without amplifying the pre amp noise.
Of course the modules did not turn on, there's got to be a ground somewhere, doesn't there. So you see how it all references to the input, the recommended way. At least I think I do.
Also, there's about a 3.5 volt drop between the cap common point of the supply that the modules reference to, and the chassis ground. That's not bad, but I believe is the cause of a very slight turn on/off pop that has developped. I trust that will vanish once I ground the signal ground to the chassis, wait, I'll tell you, yep, that took care of it nicely 😉
A little experimenting can take your amp a long way, just one little wire can make a world of difference (I've only been drinking coffee, seriously).
Time to get it in a case, almost. First I have to try paralleled 4 poles, build a softstart, finish modifying the modules.. 🙂
BTW I've seen the odd 4 pole /2 pole uni-supply online while searching for some info last week. One was kind enough to show a PCB layout for the supply they sell. It was clear they were bypassing the effectiveness of the four pole setup by externally bypassing input/output poles. Careful for that, there'd be no point in paying for four poles that way.
Question:
Has anyone tried DC coupled XLR with a external AC coupling cap to floating RCA? Could that coupling cap if left to float on the XLR permanently capacitively load the XLR in an adverse way, or induce RFI into it?
I thought it might be a way of doing unbalanced safely without the requirement of a switch or jumper, with unbalanced being AC coupled and XLR DC coupled.
Regards,
Chris
Once again I've floated my PSU, this time with the T-networks.
I didn't like what I saw at first. Yet another offset... allow me to recap (no pun intended).
First I thought the static shield could be inducing noise into my star ground point, a reasonable assumption.
So I cut that wire. Stupid move, having left the modules connected for that test (zzzzz...).
A wicked rail imbalance occured. Don't ever float your static shield! It must be earthed.
So I earthed it again, and floated the rest of the supply. A two to three volt DC imbalance occured. Not even a 1/10 as disgusting as before, but all the same, ugly.
That was with a single rectifier /center tap setup.
Next move, I upgrade. Dual FRED bridge rectifiers, 68 amp/600V PIV, and BHC T networks. That sounded nice. I had them grounded on the input side. All was well.
Next step, Mr. Stubborn decides to experiment further.
I cut the static shield wire again.... no, just kidding, that really has to be grounded.
I did cut the ground from the input side of the T-networks/rectifiers though, and soldered some new wires in so that each secondary/bridge r. /cap is fully isolated from one another at the input side, and fully floating. Disconnected the modules from the supply, popped the safety glasses on, powered it up and took a measurement. About a diode's drop worth of offset... Didn't like that, but it's not so ugly that you wouldn't tell your friends about it.
So I discharged the caps, plugged the modules in, powered it up and gave it a listen. Then I took a measurement. With the load of the modules the rails were dead equal. AAhhh, nice.
How did it sound? Expanded X10! Envelopping. The highs finally became ultra disctint, with no edge or harshness, just smooth and crystal clear. So while I may not have the double isolation transformer, and I doubt many of us do since it was only recommended just recently, I'm afraid I can't go back. At least the static shield to ground offers some measure of safety, I'll soon have myself convinced that's good enough 🙂
I thought I'd unplug my input cables and see how that little bit of hiss has changed, without amplifying the pre amp noise.
Of course the modules did not turn on, there's got to be a ground somewhere, doesn't there. So you see how it all references to the input, the recommended way. At least I think I do.
Also, there's about a 3.5 volt drop between the cap common point of the supply that the modules reference to, and the chassis ground. That's not bad, but I believe is the cause of a very slight turn on/off pop that has developped. I trust that will vanish once I ground the signal ground to the chassis, wait, I'll tell you, yep, that took care of it nicely 😉
A little experimenting can take your amp a long way, just one little wire can make a world of difference (I've only been drinking coffee, seriously).
Time to get it in a case, almost. First I have to try paralleled 4 poles, build a softstart, finish modifying the modules.. 🙂
BTW I've seen the odd 4 pole /2 pole uni-supply online while searching for some info last week. One was kind enough to show a PCB layout for the supply they sell. It was clear they were bypassing the effectiveness of the four pole setup by externally bypassing input/output poles. Careful for that, there'd be no point in paying for four poles that way.
Question:
Has anyone tried DC coupled XLR with a external AC coupling cap to floating RCA? Could that coupling cap if left to float on the XLR permanently capacitively load the XLR in an adverse way, or induce RFI into it?
I thought it might be a way of doing unbalanced safely without the requirement of a switch or jumper, with unbalanced being AC coupled and XLR DC coupled.
Regards,
Chris
classd4sure said:
Hi Chris
Nice one ... excellent result ... bring on the Jensen 4 poles
I don't think that you will need softstart with a 500VA tranny, maybe ... ???
UCD 180 and B&W DM 604 S3
I have a par of B&W DM 604 s3 speakers
Would a dual mono UCD 180 setup with 20,000 uf per module be enough for handling these speakers?
They have a good 89 db sensitivity but do drop to 2.8 ohm in the bass. Soits not en easy load.
I have a par of B&W DM 604 s3 speakers
Would a dual mono UCD 180 setup with 20,000 uf per module be enough for handling these speakers?
They have a good 89 db sensitivity but do drop to 2.8 ohm in the bass. Soits not en easy load.
No problem, and go for the high grade power supply when you would like to build true mono blocks.
Hereby a link of one of our samples; http://www.hypex.nl/applications.htm
Or, www.hypex.nl --> Applications.
Regards,
Jan-Peter
Neutrality,
I'm running 2 N804's from a single Highgrade PS and a 500VA transformer into 2 UCD400's.
I get scared of the sound pressure and the movement of the speaker cones before it sounds anywhere near compressed or clipping.
I'm sure Jan-Peter's suggestion will rule your speakers like Genghis Khan.
I'm running 2 N804's from a single Highgrade PS and a 500VA transformer into 2 UCD400's.
I get scared of the sound pressure and the movement of the speaker cones before it sounds anywhere near compressed or clipping.
I'm sure Jan-Peter's suggestion will rule your speakers like Genghis Khan.
Jan-Peter,
Is it possible on the HG PS to add a 3rd DC protection input without too much soldering?
Just thinking about a 3 channel amp for surround duties + center channel.
A lot of people go for an "uneven" number of channels because of surround systems - 5 or 7 channels, so it would be a nice feature for future PS designs as well, I think.
Thanks,
Yves
Is it possible on the HG PS to add a 3rd DC protection input without too much soldering?
Just thinking about a 3 channel amp for surround duties + center channel.
A lot of people go for an "uneven" number of channels because of surround systems - 5 or 7 channels, so it would be a nice feature for future PS designs as well, I think.
Thanks,
Yves
Seems like it could be these chassis:
http://www.thlaudio.com/casebpwrE.htm
http://www.thlaudio.com/casebpwrE.htm
An externally hosted image should be here but it was not working when we last tested it.
Jan-Peter said:
Jan,
Where can that really nice chassis be found, that looks great!
Terry🙂
P.S. sorry someone already posted before before I could see it.
Jan-Peter said:
Isnt is overkill using Dual HG psus for UCD 180?
Wouldnt it be better to just use the UCD 400 instead of UCD 180 for such a setup?
Another question, is it worth it getting the AD version of UCD 180 or 400? Taking my speakers into consideration....
Regards,
Christian
Neutrality said:
The AD version just has a better op amp. It is worth having it. It is even more worth having it if you can DC couple the module by removing the AC coupling caps which color the signal. The ability to DC couple it depends on the output DC offset of your source.
Regards,
Chris
classd4sure said:
I know it has a better OP amp, but DC coupling I dont understand. 😕
Btw, you have a UCD 180 Setup right? You feel it has enough power?
Regards,
Christian
Neutrality said:
Capacitors block DC. If you have too much DC output from your pre amp, you put a capacitor in series with it, of such a value that you don't lose too much signal, say to form a high pass filter with a cut off below the audio range, something like 6Hz.
Now all DC is blocked. That's AC coupling. Only AC signals may pass.
However, by nature of the capacitor not being a straight wire, it colors the audio signal. You then have two choices, use a better sounding cap for a more pleasing coloration, or, remove the cap, replace it with a wire, and that is DC coupling, because now even DC can get through and be amplified. That's why it depends on the level of DC output from your source, too much can fry your speaker. The accepted level of DC output from an amplifier is 50mV max.
Power, interesting question. Power doesn't only come from the module. The supply itself makes a huge difference, not only the potential of it but the bandwidth of it.
Changing my input cables to those of a proper gauge for interconnect probably doubled the power.
So, all things right, it feels like a solide 200 watts. On my speakers, at 102dB efficiency, with 15" woofers, hell yeah, all kinds of power, but they handle 400W and that would be fun too.
Regards,
Chris
Neutrality said:
I do have a UcD180 setup - and I'm certainly not lacking power. Take a look at it on http://www.frequence.dk/sites/avr300-amp.htm
It's even written in Danish ;-)
/avr300