Yes, I know. There are some complete threads for this question, but these have so many messages that have become impossible to follow them.
I think that it would be good that somebody made a summary of the best mods of the Hypex Ucd400.
And, why not?, the same about NCD and ColdAmp.
Thanks.
Ignacio.
I think that it would be good that somebody made a summary of the best mods of the Hypex Ucd400.
And, why not?, the same about NCD and ColdAmp.
Thanks.
Ignacio.
Here's what I did to my UcD 400 AD's:
UcD400 (AD)
1) Coupling caps. 22uf. They are between the opamps and the input modulator stage. Removing really clears up things. If you really need DC protection you can use a 2.2 uf quality cap before the input connector. With the 100k input impedance it forms a more than enough highpass filter (2-3Hz).
2) Current protection. Remove R13 (SMD on the bottom). I wouldn't encourage that as there seems to be not much of a difference. Don't blame me for your modules go poof if you accidentally short the output.
3) Low voltage caps (22uf/50V I believe). Replaced with 47uf/16V Rubycon ZA's. Tighter bass and overall clarity improved.
4) Main voltage caps (470uf/100V). Replaced with 2x680uf Panasonic FC (soldered another pair on the bottom of the boards). Result is deeper bass and more 'sparkle' in the highs.
5) Output filter capacitor. Replaced with .68uf/250V EPCOS polypropylene from Farnell. Opens up things quite a bit.
6) Bootstrap cap (220/16 I think). Replaced with 180uf/16V OSCON SEP. Low impedance is key here.
7) Power supply: dual mono, +/-60VDC, 1000VA, dual bridge, 18000uf, choke, 18000uf, 250uf/160V polyprops per rail/amp. (The 250uf polyprops are huge but they take care of most noise in the supply and seem to help provide a lot of details I was missing before). Adding chokes in the supply really makes things sound 'musical'. Wired with 12Ga teflon silver plated wire.
8) Separate supply for the front-end (+-12V). Used 2x12Vac 25VA trafos, with 4700uf 25V panasonic FC/dual rectifier/7812/7912 regs, CLC filtering with 82uf 16V Panasonic FC- common mode choke - 47uf/16V rubycon ZAs. Current draw is very low, you may use other types of regs such as TL431's. (Attached pdf from hypex for where to connect the supply)
And most important tweak for difficult loads, direct soldering of the power/output wires on the board (have screw-type main capacitors, I can remove the connectors from there), also added a thick solid copper wire on the module where the ground connections are (measured a tiny drop there during heavy bass passages with my speakers).
UcD400 (AD)
1) Coupling caps. 22uf. They are between the opamps and the input modulator stage. Removing really clears up things. If you really need DC protection you can use a 2.2 uf quality cap before the input connector. With the 100k input impedance it forms a more than enough highpass filter (2-3Hz).
2) Current protection. Remove R13 (SMD on the bottom). I wouldn't encourage that as there seems to be not much of a difference. Don't blame me for your modules go poof if you accidentally short the output.
3) Low voltage caps (22uf/50V I believe). Replaced with 47uf/16V Rubycon ZA's. Tighter bass and overall clarity improved.
4) Main voltage caps (470uf/100V). Replaced with 2x680uf Panasonic FC (soldered another pair on the bottom of the boards). Result is deeper bass and more 'sparkle' in the highs.
5) Output filter capacitor. Replaced with .68uf/250V EPCOS polypropylene from Farnell. Opens up things quite a bit.
6) Bootstrap cap (220/16 I think). Replaced with 180uf/16V OSCON SEP. Low impedance is key here.
7) Power supply: dual mono, +/-60VDC, 1000VA, dual bridge, 18000uf, choke, 18000uf, 250uf/160V polyprops per rail/amp. (The 250uf polyprops are huge but they take care of most noise in the supply and seem to help provide a lot of details I was missing before). Adding chokes in the supply really makes things sound 'musical'. Wired with 12Ga teflon silver plated wire.
8) Separate supply for the front-end (+-12V). Used 2x12Vac 25VA trafos, with 4700uf 25V panasonic FC/dual rectifier/7812/7912 regs, CLC filtering with 82uf 16V Panasonic FC- common mode choke - 47uf/16V rubycon ZAs. Current draw is very low, you may use other types of regs such as TL431's. (Attached pdf from hypex for where to connect the supply)
And most important tweak for difficult loads, direct soldering of the power/output wires on the board (have screw-type main capacitors, I can remove the connectors from there), also added a thick solid copper wire on the module where the ground connections are (measured a tiny drop there during heavy bass passages with my speakers).
You could also save some money and purchase the standard edition of the UCD400 and swap out the OPA2143 opamp with a LM4562 op amp which is getting all the rave reviews at the moment. While you are there, you can wire a CRD across the output for biasing the output stage in class A, but you can't use the CRD pads on the UCD as the LM4562 needs the bias on the -ve supply.
I have a couple of points about using an auxillary supply, I dont think its a worthwhile tweak especially when using the LM4562 and you can save the expense of another power supply because:
- The PSRR of the LM4562 around 100db, which is excellent, especially if you use the CRD.
- The power regulator circuit used in the UCD400 is superior to the UCD180 and according to TNT audio has pretty good performance. TNT regulator articles
- As the regulator significantly drops the voltage from the main rails and the current draw of the opamp is low, variations in the main supply due to current draw from the UCD output will not impact the regulated supply.
- Use a CRD instead of a resistor to better regulate the zener diode voltage reference improves the regulation of the supply. There is a good thread on pinkfishmedia if you want to learn more.
Also, do use two 4.7uF tantalum capacitors wired to the power supply pins of the opamp, for decoupling and improved bass.
Regards,
Dean
I have a couple of points about using an auxillary supply, I dont think its a worthwhile tweak especially when using the LM4562 and you can save the expense of another power supply because:
- The PSRR of the LM4562 around 100db, which is excellent, especially if you use the CRD.
- The power regulator circuit used in the UCD400 is superior to the UCD180 and according to TNT audio has pretty good performance. TNT regulator articles
- As the regulator significantly drops the voltage from the main rails and the current draw of the opamp is low, variations in the main supply due to current draw from the UCD output will not impact the regulated supply.
- Use a CRD instead of a resistor to better regulate the zener diode voltage reference improves the regulation of the supply. There is a good thread on pinkfishmedia if you want to learn more.
Also, do use two 4.7uF tantalum capacitors wired to the power supply pins of the opamp, for decoupling and improved bass.
Regards,
Dean
Thanks Lucpes for that 
Agree. I put Ruby ZL 270uF and bass is very deep and frightening
Clarity and HF did not suffer, wich is a good point of the Ruby caps.
Referenceaudiomods.com has Ruby ZL 470uF/100V, wich I searched for eons...perfect fit here. I don't like Pana FC, sorry.
Thanks for that!
How big the choke? and what R will be OK?
Sorry I don't remember the exact technical term for that R from the inductor.
Are the polyP the final filter caps before the modules?
Cool!
Bye,
M
Agree. I put Ruby ZL 270uF and bass is very deep and frightening
Clarity and HF did not suffer, wich is a good point of the Ruby caps.
Referenceaudiomods.com has Ruby ZL 470uF/100V, wich I searched for eons...perfect fit here. I don't like Pana FC, sorry.
Thanks for that!
How big the choke? and what R will be OK?
Sorry I don't remember the exact technical term for that R from the inductor.
Are the polyP the final filter caps before the modules?
Cool!
Bye,
M
Sound: is better than any AB amplifier I tried - speakers are a very difficult load (Infinity RSII).
Caps: Rubycon ZL/ZA is much better than Panasonic FC, IMO great care must be taken when paralleling the Rubycons with ceramic/polyprop capacitors, they simply don't need that for audio use, or you MUST use a damping resistor after the electrolytic to avoid parasitic oscillations.
Chokes: I don't know the exact value but I would choose something rated for say 10A continous and 0.4-0.7R.
Polypropylene caps (get your quality PP high uf caps in the local electrical shop as motor run caps), I put them last before the modules. Really, most factories manufacture polypropylene caps to a certain ISO standard, and most boutique or exotic caps are motor run caps labeled accordingly. I would rate these industrial caps as similar to Solen but much cheaper
Caps: Rubycon ZL/ZA is much better than Panasonic FC, IMO great care must be taken when paralleling the Rubycons with ceramic/polyprop capacitors, they simply don't need that for audio use, or you MUST use a damping resistor after the electrolytic to avoid parasitic oscillations.
Chokes: I don't know the exact value but I would choose something rated for say 10A continous and 0.4-0.7R.
Polypropylene caps (get your quality PP high uf caps in the local electrical shop as motor run caps), I put them last before the modules. Really, most factories manufacture polypropylene caps to a certain ISO standard, and most boutique or exotic caps are motor run caps labeled accordingly. I would rate these industrial caps as similar to Solen but much cheaper
Dean,
You wrote previously:
" - Use a CRD instead of a resistor to better regulate the zener diode voltage reference improves the regulation of the supply. There is a good thread on pinkfishmedia if you want to learn more."
I read the info @ Pinkfishmedia regarding this tweak. They were talking about the UCD 180's. Could you elaborate on how this will be installed on a UCD 400AD? You mentioned there are two resistors in series. Which two are they & how is the J511 installed to replace them?
Thanks
You wrote previously:
" - Use a CRD instead of a resistor to better regulate the zener diode voltage reference improves the regulation of the supply. There is a good thread on pinkfishmedia if you want to learn more."
I read the info @ Pinkfishmedia regarding this tweak. They were talking about the UCD 180's. Could you elaborate on how this will be installed on a UCD 400AD? You mentioned there are two resistors in series. Which two are they & how is the J511 installed to replace them?
Thanks
Steve,
The regulator circuit in the UCD400 is a little more sophisticated than the UCD180, in fact its quite a good regulator hence I'm sceptical providing an auxillary supply for the op amp will make much difference, especially when the LM4562 has around 100db power supply noise rejection (more than 16 bit audio!).
The resistors are the two in series between the supply rail input to the regulator and the base of the darlington regulator, and in the same spot for the UCD180. Pretty easy to spot if you trace the tracks. Be sure to install the CRD with the correct polarity (ie. its opposite for the negative rail).
[IMGhttp://pic20.picturetrail.com/VOL1293/4634025/12749957/190403940.jpg[/IMG]
Regards.
Dean
The regulator circuit in the UCD400 is a little more sophisticated than the UCD180, in fact its quite a good regulator hence I'm sceptical providing an auxillary supply for the op amp will make much difference, especially when the LM4562 has around 100db power supply noise rejection (more than 16 bit audio!).
The resistors are the two in series between the supply rail input to the regulator and the base of the darlington regulator, and in the same spot for the UCD180. Pretty easy to spot if you trace the tracks. Be sure to install the CRD with the correct polarity (ie. its opposite for the negative rail).
[IMGhttp://pic20.picturetrail.com/VOL1293/4634025/12749957/190403940.jpg[/IMG]
Regards.
Dean
deandob said:
Dean,
My UCD 400AD modules are in use, so I have looked at a few pictures of the bottom, that I have on hand.
This picture was posted @ pinkfishmedia concerning the J511 mod for the UCD 180:
An externally hosted image should be here but it was not working when we last tested it.
When I look at the pictures of the bottom of my UCD 400AD modules, I only see one such transistor (I think T5), not two like in the J511 UCD 180 mod picture.
I cant tell from my UCD 400 pics if the transistor is a PZT2222A (NPN +V) or PZT2907A (PNP -V).
Am I correct in what I am seeing & do you know which transistor it is?
Thanks
Dean,
Ok yes a picture is worth a thousand words.
So if I am seeing your picture correctly:
1. You first removed 4 resistors - 1 pair connected in series to each voltage regulator.
2. You next installed one 2 pin J511 to replace each pair of resistors.
Then if above is correct, where in the US can I get (10) J511?
Thanks
Ok yes a picture is worth a thousand words.
So if I am seeing your picture correctly:
1. You first removed 4 resistors - 1 pair connected in series to each voltage regulator.
2. You next installed one 2 pin J511 to replace each pair of resistors.
Then if above is correct, where in the US can I get (10) J511?
Thanks
Yes, that is correct. Check the image below with the schematic and trace it out on your UCD just to be sure.
The CRD replaces the resistor between the input and the base of the regulator darlington in this schematic which on the UCD is actually 2 resistors in series (not sure exactly why).
I got the J511 from Digikey when I was Stateside a couple of months back.
Regards,
Dean
An externally hosted image should be here but it was not working when we last tested it.
The CRD replaces the resistor between the input and the base of the regulator darlington in this schematic which on the UCD is actually 2 resistors in series (not sure exactly why).
I got the J511 from Digikey when I was Stateside a couple of months back.
Regards,
Dean
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