Javin5 said:
Kurt thanks for the reply,
I mean that the half of the preamp volume the bass is not very tight. It starts distort. The gain of the preamp is 20DB. I am not very technical. I just would like to ask is it happen with every amp ?or its C73 problem. When I use source signal direct with power amp UCD its perfect even with the full volume. I hope you understand what I am trying to ask.
Best wishes
Wasim
I don't think that the Pioneer preamp is a problem. A CD-player will put out about 2 Volt, which is enough to drive a UcD180 to its full power. If you add an additional 20 dB of gain (a factor of 10), than that's much more than you need and you have to decrease this by the volume control, otherwise you will severely overdrive the input of the UcD180.
Since the highest levels are often found in the bass notes, the low frequencies will start to distort first. In addition, as TerryO pointed out earlier, many speakers will severly distort if you apply the full power of an UcD180 at low fequencies.
The conclusion is that it is quite natural that you cannot utilize the full gain of the C73. If I remember correctly, older preamps were built assuming around 250 mV from "high level" sources. Newer preamps generally have less gain, sometimes they are merely unity gain buffers or even passive. And some CD-players have a volume control and you can directly connect them, without a preamp, to a power amp. I have also seen external attenuators, which can be connected between cd-player and preamp to reduce overall gain and operate the volume control more in the middle position than in the first few degrees of the rotation angle.
Since the highest levels are often found in the bass notes, the low frequencies will start to distort first. In addition, as TerryO pointed out earlier, many speakers will severly distort if you apply the full power of an UcD180 at low fequencies.
The conclusion is that it is quite natural that you cannot utilize the full gain of the C73. If I remember correctly, older preamps were built assuming around 250 mV from "high level" sources. Newer preamps generally have less gain, sometimes they are merely unity gain buffers or even passive. And some CD-players have a volume control and you can directly connect them, without a preamp, to a power amp. I have also seen external attenuators, which can be connected between cd-player and preamp to reduce overall gain and operate the volume control more in the middle position than in the first few degrees of the rotation angle.
Just for fun, one pic of my ucd!
An externally hosted image should be here but it was not working when we last tested it.
PS upgrade.
To whom it may be of interest:
UCD amps also benefit from the "charge transfer" power supply develloped by -ECdesigns- on his thread about Ultimate NOS DAC. Just adapt to needed voltages and current capability of active units.
http://picasaweb.google.com/lh/photo/rOgiSl8IVgPdqOcKLPkbNA?feat=directlink
I did not implement the "capacitance multiplier" part of the circuit yet, because of space constraints.
This mod cleans up the sound quite a bit.
I used IRF5210 for the Pchannel Mosfet, IRF930 for the N channel (if I remember correctly) and a high current high V for the power Schottkies. C1 is a 10000uF Panasonic TSHA and C2 is a 10000 BHC big can capacitor, per side.
I hope you like it,
M
To whom it may be of interest:
UCD amps also benefit from the "charge transfer" power supply develloped by -ECdesigns- on his thread about Ultimate NOS DAC. Just adapt to needed voltages and current capability of active units.
http://picasaweb.google.com/lh/photo/rOgiSl8IVgPdqOcKLPkbNA?feat=directlink
I did not implement the "capacitance multiplier" part of the circuit yet, because of space constraints.
This mod cleans up the sound quite a bit.
I used IRF5210 for the Pchannel Mosfet, IRF930 for the N channel (if I remember correctly) and a high current high V for the power Schottkies. C1 is a 10000uF Panasonic TSHA and C2 is a 10000 BHC big can capacitor, per side.
I hope you like it,
M
Hi Guys
I have a 6 channel UCD180HG power by 3 SMP180 built by my friend. I have been using it trouble free for some time, until recently I purchase a Behringer DCX2496 to do crossover work for my 3 way speaker.
As soon as plug it in, i got a really loud hum from my speaker, and I do mean really loud, I have to disconnect my mid and tweeter to prevent damage. I have talk to the Behringer support, and they replace with another unit, same problem...
My friend told me that the amp is floating ground, and I know that DCX2496 is grounded, is it the reason that it hum? Below is my connection diagram
USB Soundcard -> TRS/XLR (balance) -> DCX2496 -> XLR -> amp.
I have try disconnect everything leaving only DCX2496 -> XLR -> amp, the DCX is power off and disconnect from wall socket, but it still hum. I have try to find way to fix this problem no solution yet.
Any help is much appreciated, thanks in advance.
I have a 6 channel UCD180HG power by 3 SMP180 built by my friend. I have been using it trouble free for some time, until recently I purchase a Behringer DCX2496 to do crossover work for my 3 way speaker.
As soon as plug it in, i got a really loud hum from my speaker, and I do mean really loud, I have to disconnect my mid and tweeter to prevent damage. I have talk to the Behringer support, and they replace with another unit, same problem...
My friend told me that the amp is floating ground, and I know that DCX2496 is grounded, is it the reason that it hum? Below is my connection diagram
USB Soundcard -> TRS/XLR (balance) -> DCX2496 -> XLR -> amp.
I have try disconnect everything leaving only DCX2496 -> XLR -> amp, the DCX is power off and disconnect from wall socket, but it still hum. I have try to find way to fix this problem no solution yet.
Any help is much appreciated, thanks in advance.
Hi maxlorenz,
I would be greatful if you can answer...
Did you use for one way a transformer with 4 secondary or only 2 ?
Did you join (-) for the positive side and (+) for negative to form GND before connecting to UCD GND
And may be stupid question, but is the rectifier & charge transfer to be directly connected to secondary or can the transformer be first tight to some bride rectifier and then to the charge transfer PSU ?
Hi Rtd,
My Tx has dual secondaries and center tap is formed the usual way, as you commented (your Tx or the seller-s website surely shows a connection diagram). Only one ground is formed> the two CT circuits must combine as this is the non floating version. ECdesigns has shown on his ultimate DAC thread a floating charge transfer PS that could be also adapted for this amp, but that needs 4 secondaries...
The Tx can be connected directly to the CT circuit as the diagram shows, but I guess you can interpose some passive like rectifier diode or power resistor, should you want to reduce V or limit charging current...
Regards,
M
My Tx has dual secondaries and center tap is formed the usual way, as you commented (your Tx or the seller-s website surely shows a connection diagram). Only one ground is formed> the two CT circuits must combine as this is the non floating version. ECdesigns has shown on his ultimate DAC thread a floating charge transfer PS that could be also adapted for this amp, but that needs 4 secondaries...
The Tx can be connected directly to the CT circuit as the diagram shows, but I guess you can interpose some passive like rectifier diode or power resistor, should you want to reduce V or limit charging current...
Regards,
M
Hi folks.
I'd like to try a 180 to drive my 98db/SPL speakers. Currently it is driven with a Tripath 2021B (12V battery supply).
I am planning for a gain setting of 9db (instead of 26db).
This way I could drive my DAC without severe digital volume control on the PC side.
As far as I've seen I need to change RG (=R10 on UCD180 according to application note) to accomplish this.
Can I go that low with the gain? Any problems I'd run into? What's the lowest possible gain - since I could also use a 2V differential output of the Zapfilter instead of my SE 1.6V passive output of my DAC?
What type of resistor should i use? Any advise how to handle the tricky SMD-R swap?
THX for your advise
Cheers
I'd like to try a 180 to drive my 98db/SPL speakers. Currently it is driven with a Tripath 2021B (12V battery supply).
I am planning for a gain setting of 9db (instead of 26db).
This way I could drive my DAC without severe digital volume control on the PC side.
As far as I've seen I need to change RG (=R10 on UCD180 according to application note) to accomplish this.
Can I go that low with the gain? Any problems I'd run into? What's the lowest possible gain - since I could also use a 2V differential output of the Zapfilter instead of my SE 1.6V passive output of my DAC?
What type of resistor should i use? Any advise how to handle the tricky SMD-R swap?
THX for your advise
Cheers
Do it like this:
Link: http://www.diyaudio.com/forums/class-d/115388-hybrid-hypex-ucd.html
Bypassing the pre/opamp leave's 4,5 x gain and you got less noise and better sound.
First i used to resitor change, then i tryed the opamp bypass. For me the last was the best and the easiest to perform.
Ronny
Link: http://www.diyaudio.com/forums/class-d/115388-hybrid-hypex-ucd.html
An externally hosted image should be here but it was not working when we last tested it.
Bypassing the pre/opamp leave's 4,5 x gain and you got less noise and better sound.
First i used to resitor change, then i tryed the opamp bypass. For me the last was the best and the easiest to perform.
Ronny
Hi Ronny.
That looks interesting. Though I have a UCD180HG V2 board which looks different.
Gain (Voltage?) of 4.5 might do at 0db=1.6V =7.2V ends up at 3.2W at my 16R/98db/W speakers.
Better choice would be to use my Zapfilter in differential mode. I'll see later how it works.
Anyhow - I need to figure out how to do the tweak on my modules.
Step one: I would like to leave the coupling caps in and just bypass the LM4562.
BTW: I have the funny feeling that it can't be RG=R10 on my module. R10 is sitting on the Regs. R11/R12 (should be R12/R13 I guess ) seems also to be wrong There must be an error in the Hypex application note.
That looks interesting. Though I have a UCD180HG V2 board which looks different.
Gain (Voltage?) of 4.5 might do at 0db=1.6V =7.2V ends up at 3.2W at my 16R/98db/W speakers.
Better choice would be to use my Zapfilter in differential mode. I'll see later how it works.
Anyhow - I need to figure out how to do the tweak on my modules.
Step one: I would like to leave the coupling caps in and just bypass the LM4562.
BTW: I have the funny feeling that it can't be RG=R10 on my module. R10 is sitting on the Regs.
R11/R12 (should be R12/R13 I guess ) seems also to be wrong There must be an error in the Hypex application note.