I agree completelly 😀
M.
PS: anybody tried DIY "technical balanced power" with UCD yet?
http://www.equitech.com/articles/articles.html
Not with the UcD's, but I use DIY Felicia's http://www.audiocircle.com/circles/index.php?topic=18441.0 (thank you Occam and JoshK!) with my preamps and front ends, highly recommended! I've also run a Tripath based Carver amp and the Teac 700b(?) with a BPT balanced conditioner, also very effective at removing background noise / adding to overall clarity. No need for BP with the UcD 400's as they're powered by +/- 48v battery supplies...
Just noticed that my wireless mouse (rf) hardly works when the 3 channel UCD400 amp is powered on. Power supplies ar floating. RCA inputs wired as JP and Bruno suggested. Should I earth ground my chassis or should I look for a cure of the source of RF ? If that is possible.
Dave
Dave
if there is that much rfi emission, how it the module pass UL/CE certification? or is it certified at all?
Ok -- So I just went down to the theater to check again. Wireless mouse is working fine now with UCDs powered on. When it did it before I turned off the amp and mouse was ok. Possible that something else is interferring with mouse. Now I'm not so sure it's the UCDs.
Dave
Dave
Hi,
Anyone dared to try opa627's on the latest revision of UCD400 with stock bypassing? I'll plugging some in shortly anyway.
Anyone dared to try opa627's on the latest revision of UCD400 with stock bypassing? I'll plugging some in shortly anyway.
Is this tweak to the UCD400 opamp regulator OK?
Hi,
I have a question about the onboard regulator for the UCD400. It is an area that can be tweaked IMO and does not seem to be much discussed here.
The regulator is a simple zener & emitter follower darlington configuration on the UCD board. I think it can be improved by removing the zener bias resistor with a constant current source (eg. J511) to reduce the low frequency supply rejection, as well as put a resistor (eg. 240 ohms) in series with zener to improve the zener noise.
You can see a similar circuit here with comparison testing.
http://www.tnt-audio.com/clinica/regulators_noise3_e.html
It should also benefit from a series resistor (eg. 10 ohms) and electro (eg. 47uf) in front of the regulator, forming a RC filter. This will raise the impedence of the regulator, so a good high value cap (eg. tantalum) across the power supply of the op amp will help here, increasing dynamics and bass.
Any thoughts on my theory. If no one says I'll blow myself up I'll give it a try during the week.
Regards,
Dean
Hi,
I have a question about the onboard regulator for the UCD400. It is an area that can be tweaked IMO and does not seem to be much discussed here.
The regulator is a simple zener & emitter follower darlington configuration on the UCD board. I think it can be improved by removing the zener bias resistor with a constant current source (eg. J511) to reduce the low frequency supply rejection, as well as put a resistor (eg. 240 ohms) in series with zener to improve the zener noise.
You can see a similar circuit here with comparison testing.
http://www.tnt-audio.com/clinica/regulators_noise3_e.html
It should also benefit from a series resistor (eg. 10 ohms) and electro (eg. 47uf) in front of the regulator, forming a RC filter. This will raise the impedence of the regulator, so a good high value cap (eg. tantalum) across the power supply of the op amp will help here, increasing dynamics and bass.
Any thoughts on my theory. If no one says I'll blow myself up I'll give it a try during the week.
Regards,
Dean
Re: Is this tweak to the UCD400 opamp regulator OK?
Hi Dean,
link does not work. I've put some ZL's(100uF/16V) on the zener diodes and supply pins of the opamp. Works like a charm.
deandob said:
Hi Dean,
link does not work. I've put some ZL's(100uF/16V) on the zener diodes and supply pins of the opamp. Works like a charm.
I already replaced the resistor biasing the zener in my UCD180 with current regulator diodes, I also added capacitors after the dropper resistors to make a RC filter, its nice mod and worth doing
Hi Deandob,
This mod has been discussed at Pink Fish media, for UCD180, If I recall well.
Hi T.
I thought you might be interested in this:
RubyconZL 470uF/100V
I found them at referenceaudiomods.com
Perfect fit for UCD400, too big for UCD180
Did the swap, together with output filter cap (polyester 0u68), but could not listen to it yet 🙁 Sunday (suny-day) at work!
Cheers,
M
This mod has been discussed at Pink Fish media, for UCD180, If I recall well.
Hi T.
I thought you might be interested in this:
RubyconZL 470uF/100V
I found them at referenceaudiomods.com
Perfect fit for UCD400, too big for UCD180
Did the swap, together with output filter cap (polyester 0u68), but could not listen to it yet 🙁 Sunday (suny-day) at work!
Cheers,
M
maxlorenz said:Hi Deandob,
This mod has been discussed at Pink Fish media, for UCD180, If I recall well.
Hi T.
I thought you might be interested in this:
RubyconZL 470uF/100V
I found them at referenceaudiomods.com
Perfect fit for UCD400, too big for UCD180
Did the swap, together with output filter cap (polyester 0u68), but could not listen to it yet 🙁 Sunday (suny-day) at work!
Cheers,
M
Thanks M🙂
I'll look forward to your listening impressions, should be interesting to see how the ZL's work in the UCD
Don't they do a 63v version?
T,
There is a 63V version but, halas, introuvable ...
I will have to drill the T piece from the 180's or install 50VDC caps with other transformer to get +/-45VDC rails 🙁
Look at my ugly superE-cap arrangement that replaced the small ceramic opamp power supply caps 😉 (my camera can't zoom enough; the bottom side is foggy)
Cheers,
M
There is a 63V version but, halas, introuvable ...
I will have to drill the T piece from the 180's or install 50VDC caps with other transformer to get +/-45VDC rails 🙁
Look at my ugly superE-cap arrangement that replaced the small ceramic opamp power supply caps 😉 (my camera can't zoom enough; the bottom side is foggy)
An externally hosted image should be here but it was not working when we last tested it.
Cheers,
M
Guys,
Sorry about the link, try this instead. These TNT articles about regulator performance are quite informative.
http://www.tnt-audio.com/clinica/regulators_noise3_e.html
T, regarding the dropper resistors in the UCD180, my model (dated 10/8/2004) does not have any resistor in series with the regulator, it has a direct connection to the shunt transistor.
Jan-Peter, is this something that came out with later revisions of the UCD180? Is it something that I can retrofit to the UCD to add a RC filter in front of the regulator? What is the value of the series resistor?
Actually my question was more about the UCD400, which will drive the front stereo speakers for my multichannel amp. I did get the idea about modding the regulator from the pink fish media forum although that thread seems to have gone quiet. I have put 4.7uF tantalum caps to decouple the opamp (swapped for the new LM opamp that is all the rage at the moment) but like my older UCD180 (my UCD400 is 21/04/2005) there are no series resistors before the regulator or after the regulator to make a RC filter with. My two questions are:
1) Will I loose dynamics & bass if I add a series resistor in the op amp supply line either before or after the regulator? Maybe a ferrite bead would be a better option?
2) The TNT article has a resistor in series with the zener diode which with the capacitor on the base of the regulator darlington will form another RC filter in a critical spot, reducing noise. Is this something that could be done with the UCD400 regulator? This tweak is not in the pink fish media thread.
Maybe tweaking the regulator is a waste of time as the LM opamp has >100db PSRR over the audio range anyway, however a number of people who have tried it say it makes a difference.
Another interesting point on the UCD400 is that there are actually 2 zener bias resistors in series when only one would have sufficed - maybe Hypex meant for there to be another part in series with the bias resistor (eg. a constant current source).
Regards,
Dean
Sorry about the link, try this instead. These TNT articles about regulator performance are quite informative.
http://www.tnt-audio.com/clinica/regulators_noise3_e.html
T, regarding the dropper resistors in the UCD180, my model (dated 10/8/2004) does not have any resistor in series with the regulator, it has a direct connection to the shunt transistor.
Jan-Peter, is this something that came out with later revisions of the UCD180? Is it something that I can retrofit to the UCD to add a RC filter in front of the regulator? What is the value of the series resistor?
Actually my question was more about the UCD400, which will drive the front stereo speakers for my multichannel amp. I did get the idea about modding the regulator from the pink fish media forum although that thread seems to have gone quiet. I have put 4.7uF tantalum caps to decouple the opamp (swapped for the new LM opamp that is all the rage at the moment) but like my older UCD180 (my UCD400 is 21/04/2005) there are no series resistors before the regulator or after the regulator to make a RC filter with. My two questions are:
1) Will I loose dynamics & bass if I add a series resistor in the op amp supply line either before or after the regulator? Maybe a ferrite bead would be a better option?
2) The TNT article has a resistor in series with the zener diode which with the capacitor on the base of the regulator darlington will form another RC filter in a critical spot, reducing noise. Is this something that could be done with the UCD400 regulator? This tweak is not in the pink fish media thread.
Maybe tweaking the regulator is a waste of time as the LM opamp has >100db PSRR over the audio range anyway, however a number of people who have tried it say it makes a difference.
Another interesting point on the UCD400 is that there are actually 2 zener bias resistors in series when only one would have sufficed - maybe Hypex meant for there to be another part in series with the bias resistor (eg. a constant current source).
Regards,
Dean
Hi M, I'll have another search for those 63v ZL's, my HT voltage is 42v, I still don't fancy risking 50v caps here to be honest.
I'm going to leave the small ceramic bypass cap for the op-amps and may add an additional 10uf ZL later or possibly a 1uf tant
Hi Dean, there are 1k resistors on my UCD180, these are dropping the voltage to around 30 odd volts, I added 10uf after these.
I was impressed with replacing those 15k smd resistors biasing the zener with CRD's, it made a small but noticeable improvement.
I don't know the UCD400 regulation circuit so can't really comment how it would work there
I'm now using LM4562's input op-amps, I found these to be much better than the AD8620's, the SMD CRD's on the outputs have been hardwired to the LM4562's positive rail instead of the UCD180's -rail as it was originally for the AD8620
I am currently trying to sort a case out, problem is only one of my transformers would fit so I'm deciding if to have a single transformer running both modules in the same case or have two transformers in a separate case
I'm going to leave the small ceramic bypass cap for the op-amps and may add an additional 10uf ZL later or possibly a 1uf tant
Hi Dean, there are 1k resistors on my UCD180, these are dropping the voltage to around 30 odd volts, I added 10uf after these.
I was impressed with replacing those 15k smd resistors biasing the zener with CRD's, it made a small but noticeable improvement.
I don't know the UCD400 regulation circuit so can't really comment how it would work there
I'm now using LM4562's input op-amps, I found these to be much better than the AD8620's, the SMD CRD's on the outputs have been hardwired to the LM4562's positive rail instead of the UCD180's -rail as it was originally for the AD8620
I am currently trying to sort a case out, problem is only one of my transformers would fit so I'm deciding if to have a single transformer running both modules in the same case or have two transformers in a separate case
Hi,
I'm currently working on my UcD400 dual-mono amplifier.
These are the parts I allready have:
- 2x Velleman trafo, 39V, 300VA.
- 8x Elna Black Neg, 10.000uF, 63V.
- 2x Diode, 300V, 35A
I will order the UcD400 modules when the rest of the parts are installed. Before I begin, I had a few questions about making my own power supply:
1. I'm using 300VA for each channel. Do I need a soft-start circuit, or will this work on a normal on/off switch?
2. The trafo delivers 39 Volts. Howmuch Volts will this be áfter the diode? (How can I calculate this?)
Thanks a lot for helpint me out😎
Regards,
Barry Loef
I'm currently working on my UcD400 dual-mono amplifier.
These are the parts I allready have:
- 2x Velleman trafo, 39V, 300VA.
- 8x Elna Black Neg, 10.000uF, 63V.
- 2x Diode, 300V, 35A
I will order the UcD400 modules when the rest of the parts are installed. Before I begin, I had a few questions about making my own power supply:
1. I'm using 300VA for each channel. Do I need a soft-start circuit, or will this work on a normal on/off switch?
2. The trafo delivers 39 Volts. Howmuch Volts will this be áfter the diode? (How can I calculate this?)
Thanks a lot for helpint me out😎
Regards,
Barry Loef
People say that a softstart is needed above 500VA so you might try without one if you use slow fuses, for fast fuses you would need a softstart.
After the diodes voltage drops by .7 volts (negligible) but after the ELNAs, voltage will go up, multiply by 1.414, because the caps integrate the AC current to the maximum crest to crest voltage. So 39*1.414=about 55 volts DC (+ and minus rails).
I assume your diodes are actually a diode bridge (4 diodes in one device with 4 connectors) and that your trafo has dual 39 secondaries (4 wires).
Are you planning to use 2 ELNA Cerafines in parallel per rail? Bruno Putzeys made a comment that paralled identical caps don't sound as good but then Hypex's own HG supply uses paralleled caps. I am interested in pros and cons regarding parallel caps.
Guy
After the diodes voltage drops by .7 volts (negligible) but after the ELNAs, voltage will go up, multiply by 1.414, because the caps integrate the AC current to the maximum crest to crest voltage. So 39*1.414=about 55 volts DC (+ and minus rails).
I assume your diodes are actually a diode bridge (4 diodes in one device with 4 connectors) and that your trafo has dual 39 secondaries (4 wires).
Are you planning to use 2 ELNA Cerafines in parallel per rail? Bruno Putzeys made a comment that paralled identical caps don't sound as good but then Hypex's own HG supply uses paralleled caps. I am interested in pros and cons regarding parallel caps.
Guy
Hello all, I have a few dumb questions about the UCD400.
First, my possible use for it would be a two channel power amp, for a pair of 10" subs. I would like to get the full output power the modules are capable of.
I have a case, heatsinks, supply caps, and most of the small bits. The major cost would the modules and the transformer. I'm thinking a 500VA 40-0-40 Torroid would be the correct size. Can i go smaller to say a 330VA, or is 500VA the minimum for two UCD's?
I've read alot of conflicting posts about the secondary voltage. Is 40-0-40 okay for the UCD400? It would be about 55.5vdc i believe after rectification.
Next up, how does the turn on pin work on the amp, is that just a stand-by function and you don't need to use it? Or is it actually needed for the amp to power up? I would like to just do a simple switch on the mains. I don't need a stand-by switch for this amp.
I have a pair of Hafler amps, that use no softstart circuits and have large transformers, but they are EI type. Is a softstart needed for a 500VA torroid?
Thanks for any help guys.
First, my possible use for it would be a two channel power amp, for a pair of 10" subs. I would like to get the full output power the modules are capable of.
I have a case, heatsinks, supply caps, and most of the small bits. The major cost would the modules and the transformer. I'm thinking a 500VA 40-0-40 Torroid would be the correct size. Can i go smaller to say a 330VA, or is 500VA the minimum for two UCD's?
I've read alot of conflicting posts about the secondary voltage. Is 40-0-40 okay for the UCD400? It would be about 55.5vdc i believe after rectification.
Next up, how does the turn on pin work on the amp, is that just a stand-by function and you don't need to use it? Or is it actually needed for the amp to power up? I would like to just do a simple switch on the mains. I don't need a stand-by switch for this amp.
I have a pair of Hafler amps, that use no softstart circuits and have large transformers, but they are EI type. Is a softstart needed for a 500VA torroid?
Thanks for any help guys.
I'm thinking about using one of these amps for a subwoofer. The spec sheet doesn't say if it's 400w RMS or some other measurement.
I am planning on getting a Peerles XXLS 12" driver. Should I get the 4 or 8 Ohm version?
I am planning on getting a Peerles XXLS 12" driver. Should I get the 4 or 8 Ohm version?
FlappySocks said:
Sorry to answer my own question... but need the 8 Ohm driver according to Peerless's spec sheet.
How many Watts RMS will this amp give me at 8 Ohms?