My (very) mini review of the Singxer SU-1 DDC

[LoryWiv]

Thanks, scan80269, I'm usually a "turn it off when not in use" kind of guy but but with minimal power draw or thermal risk, SU-1 may be the exception to keep the clock stable and happy.

[Energy]

19 hours ago, pkane2001 said:

I'm curious: what would be an example of a lower noise replacement for the stock 5v regulator? I still can't bring myself to pay for a power supply that costs as much as SU-1

 

With $50 you have two choices.

 

1. Replace stock linear power supply with an iFi iPower 5V will offer 1µV (in theory if your AC mains is perfectly quiet) but since it is a switch mode power supply (SMPS) will have more AC leakage currents seeping through

2.  Replacing the LM2940CT-5 (5V) with Sparkos Labs SS78XX 5V will offer 3µV and contain less AC leakage current than the first choice.

 

In terms of installation wise, #1 would probably be easiest. But if I was given these two choices, I'd most likely go with #2.

 

After using the UpTone LPS-1 I've come to realize that even though it has slightly higher noise (4.17µV), but through it's complete removal of AC leakage currents, it has a big affect on the overall sound which I found to be much more important than just a few microvolts of noise. Having said that, I would more so push for improving the stock linear power supply with the discrete voltage regulator instead. A strong 5V battery can also remove these currents completely but does not have fast response or power like the LPS-1. Since the unit has to be on for 90 minutes until achieving optimal performance, imagine how many batteries you will have to go through.

 

Anyways, I'd recommend changing out the electrolytic capacitors on the power supply board with some Panasonic FR and the four 0.1µF generic film capacitors with some WIMA MKP2 for it's better self-healing capabilities.

 

And if you're going to do this, I say go even further and change the two electrolytic capacitors near the SS1117XX from your previous mod with Panasonic FR 330µF (or preferably 220µF if available) in either 25V or 35V. Looks like the top of one of your caps got dented in. Change the remaining 3 on the main board with Nichicon FPCAP R7 220µF 6.3V.

 

The stock voltage regulator on the power supply runs fairly warm so when you change it to the discrete voltage regulator, you should apply a good layer of non conductive thermal paste (like Gelid GC-Extreme) in between the two to keep the regulator cool. 

 

Total modifications will probably cost you roughly $60-65.

Once you do everything correctly, the improvements from an LPS-1 will be so minimal that I wouldn't see it be justifiable for $400.

 

16 hours ago, pkane2001 said:

Do you know what current SU-1 draws? The stock regulator is rated for 1A. I would assume that I should pick a replacement rated for 1A, as well.

 

The entire unit will draw less than 1A for sure that's why even if the Sparkos Labs discrete voltage regulator has a voltage drop of <2V it's perfectly fine to use as it takes 7V + 7V and can still achieve 5V output. It has lower noise than the Belleson and higher input rejection rate. As said previously, pair it with Panasonic FR's and it'll do even better.

 

16 hours ago, elan120 said:

Hi @pkane2001, I did not measure the current consumption for the entire SU-1, but I did measure the current draw from LPS-1 to 5V main board input, and that is 110~115mA.  The current draw for the 5V main board likely will be less than 150mA, so the 3 choices mentioned earlier, including LT3045 will work just fine.

 

For the SU-1 both Sparkos Labs and Belleson will work just fine. Sparkos being a little better. Linear Technology LT3045 would be a better choice but unfortunately it does not come in a TO-220 or DPAK package. It's other family LT3081 does but is noisy coming in at 27µV.

 

3 hours ago, LoryWiv said:

Thanks, scan80269, I'm usually a "turn it off when not in use" kind of guy but but with minimal power draw or thermal risk, SU-1 may be the exception to keep the clock stable and happy.

 

I wouldn't keep my amplifiers on 24/7 but surely for DAC's and or transport sources.

 

Sometimes I would catch myself accidentally turning off my DAC so I'd give it at least an hour of warm up time before really judging to see if any modifications has made an improvement or if it really was just the DAC that improved the more I listened. But yeah, SU-1 should be on all the time.

[pkane2001]

2 hours ago, Energy said:

With $50 you have two choices.

 

1. Replace stock linear power supply with an iFi iPower 5V will offer 1µV (in theory if your AC mains is perfectly quiet) but since it is a switch mode power supply (SMPS) will have more AC leakage currents seeping through

2.  Replacing the LM2940CT-5 (5V) with Sparkos Labs SS78XX 5V will offer 3µV and contain less AC leakage current than the first choice.

 

Thanks for such a detailed answer, @Energy! I already have iFi iPower 5v. I was thinking about possibly enhancing the stock LPS to see if I can get it closer to LPS-1 performance without spending $400, and you've given me all the details on how to proceed.

 

Also, thank you for noticing the dented capacitor! I didn't see it when I was putting in the regulator. Had a look just now, and indeed, it looks like it was dented with a sharp object. Definitely a candidate for replacement.

[pkane2001]

On 5/7/2017 at 7:48 AM, Energy said:

SU-1 Power Board:

- (1) Panasonic FR 1000μF 25V 18mΩ

- (3) Panasonic FR 470μF 25V 30mΩ

 

By the way, I think you have these swapped. There are 3 x 1000μF and 1 x 470μF capacitors on the stock power supply. Just looking at the board now.

[Energy]

1 hour ago, pkane2001 said:

Thanks for such a detailed answer, @Energy! I already have iFi iPower 5v. I was thinking about possibly enhancing the stock LPS to see if I can get it closer to LPS-1 performance without spending $400, and you've given me all the details on how to proceed.

 

Also, thank you for noticing the dented capacitor! I didn't see it when I was putting in the regulator. Had a look just now, and indeed, it looks like it was dented with a sharp object. Definitely a candidate for replacement.

 

If that's the case then you can get the money back by selling the iPower and conducting the voltage regulator mod on the stock linear power supply. You'll get similar noise performance as the LPS-1 but much lower AC leakage current than the iPower. It'll also be better on your AC mains as well since linear power supplies bleed less noise back into the mains that they're connected to.

 

Once you have all of the mods done you're only missing out on 5% or so from the small incremental benefit of the LPS-1 which in my opinion at that point won't be worth $400 but YMMV. Those who can justify it can go right ahead and do so. For that amount of money I would rather spend on an ISO REGEN + iPower 9V.

 

28 minutes ago, pkane2001 said:

By the way, I think you have these swapped. There are 3 x 1000μF and 1 x 470μF capacitors on the stock power supply. Just looking at the board now.

 

You're right, good looking out.

 

Check the datasheet for Panasonic FR and get 16V or 25V depending on you. In 1000µF and 470µF values, get whichever one has lower ESR in milliohms (impedance) for those two voltage ratings.

[pkane2001]

4 minutes ago, Energy said:

 

If that's the case then you can get the money back by selling the iPower and conducting the voltage regulator mod on the stock linear power supply. You'll get similar noise performance as the LPS-1 but much lower AC leakage current than the iPower. It'll also be better on your AC mains as well since linear power supplies bleed less noise back into the mains that they're connected to.

 

Great! Thanks again. The 5v iFi supply was actually purchased as part of another package, so it just happened to be around for me to try it. I didn't have to buy it for this project. 

 

[Energy]

33 minutes ago, pkane2001 said:

Great! Thanks again. The 5v iFi supply was actually purchased as part of another package, so it just happened to be around for me to try it. I didn't have to buy it for this project. 

 

 

That's great. Thanks to it you were able to further see the benefits of a lower noise floor.  

 

There will be a small incremental benefit once you keep the noise floor and eliminate AC leakage currents in the process. I'm not sure how good the dynamic noise suppression circuitry is on the iFi Audio unit but I doubt it can compare to regulation of a linear power supply due to the use of a larger transformer and filtering platform but who knows.

 

Since you're going at it with the mods, I say you replace the stock internal DC power cable with a low inductance Canare 4S6 Star Quad.  Free shipping from Markertek. The length is so short that I personally might not bother but then again, who knows. 

[pkane2001]

26 minutes ago, Energy said:

Since you're going at it with the mods, I say you replace the stock internal DC power cable with a low inductance Canare 4S6 Star Quad.  Free shipping from Markertek. The length is so short that I personally might not bother but then again, who knows. 

 

I can't imagine that it would matter in such a short run, but I'll at least twist the cables.

 

[Energy]

Check out the DC cable thread from UpTone. I believe it's better to twist counter clockwise for common mode noise rejection. I would also double up the wire gauge.

[scan80269]

5 hours ago, pkane2001 said:

By the way, I think you have these swapped. There are 3 x 1000μF and 1 x 470μF capacitors on the stock power supply. Just looking at the board now.

I ended up installing 3 x 2200uF 25V + 1 x 1000uF 25V Panasonic FR caps for the stock LPS.  For the film caps I used Kemet 0.1uF PPS.  I didn't change out the regulator since by the time the caps got replaced I had convinced myself to pursue powering the SU-1 with an UpTone LPS-1 instead.

 

I was also going to replace the bridge rectifier on the stock LPS with a Schottky bridge, but didn't manage that either...

 

[scan80269]

8 hours ago, Energy said:

For the SU-1 both Sparkos Labs and Belleson will work just fine. Sparkos being a little better. Linear Technology LT3045 would be a better choice but unfortunately it does not come in a TO-220 or DPAK package. It's other family LT3081 does but is noisy coming in at 27µV.

I just ordered one LT3045 soldered onto a small PCB with LM317 pinout on eBay.

 

The LT3045 has a lower noise spec than the Sparkos Labs discrete regulator but poorer PSRR.  It would be interesting to compare these two directly on the SU-1 to see which one comes out ahead SQ wise.

 

[Energy]

49 minutes ago, scan80269 said:

I just ordered one LT3045 soldered onto a small PCB with LM317 pinout on eBay.

 

The LT3045 has a lower noise spec than the Sparkos Labs discrete regulator but poorer PSRR.  It would be interesting to compare these two directly on the SU-1 to see which one comes out ahead SQ wise.

 

 

Can I get the link? 

 

Did you order one for the SU-1?

 

I have an LM317D2 I want to replace that takes 10.3V and outputs 1.2V. Unforunately the Sparkos can only go as low as 3.3V since that's the working voltage it needs to power the onboard discrete components.

 

Does the seller have the LT3045 in LM317 pinout with a fixed output voltage or do we have to work the voltage divider ourselves?

[scan80269]

2 minutes ago, Energy said:

 

Can I get the link? 

 

Did you order one for the SU-1?

 

I have an LM317D2 I want to replace that takes 10.3V and outputs 1.2V. Unforunately the Sparkos can only as low as 3.3V as that's the working voltage it needs to power it's discrete components.

 

Does the seller have the LT3045 in LM317 pinout with a fixed output voltage or do we have to work the voltage divider ourselves?

LM317 pinout:

http://www.ebay.com/itm/LT3045-Ultralow-noise-0-8-VRMS-LDO-linear-regulators-0V-15V-0-5A-LM317-Layout-/252880465477?hash=item3ae0d9ae45:g:1fcAAOSwXYtYyCH-

 

78xx pinout:

http://www.ebay.com/itm/LT3045-Ultralow-noise-0-8-VRMS-LDO-linear-regulators-0V-15V-0-5A-78xx-Layout-/252880467320?hash=item3ae0d9b578:g:jSMAAOSwol5YyCO1

 

You send the seller a note about the desired output voltage.  If you want a different output voltage later I believe one resistor on the board can be changed.

 

I ordered one LM317 pinout version for my SU-1.

 

[elan120]

4 minutes ago, Energy said:

 

Can I get the link? 

 

Did you order one for the SU-1?

 

I have an LM317D2 I want to replace that takes 10.3V and outputs 1.2V. Unforunately the Sparkos can only go as low as 3.3V since that's the working voltage it needs to power the onboard discrete components.

 

Does the seller have the LT3045 in LM317 pinout with a fixed output voltage or do we have to work the voltage divider ourselves?

I have been using the one from here:  http://www.ldovr.com/default.asp

 

They also sell on eBay, likely the one @scan80269 ordered.  They have LT3045 in few different configurations, including LM31X or LM78XX pin outs.  It is a direct replacement for either LD1086 or LM2940CT-5, but make sure specify your voltage requirement on order page.  They also have a unit with single resistor for output setting, which may fit your needs.  

 

[Energy]

Thanks guys. I'll leave the SS11173.3 in the Singxer SU-1 for now at least until you one your experimentations shows that the lower 0.8µV noise can sound better than the 3.2µV. Not very far away and I reckon the higher PSSR on the Sparkos Labs will offer more sonic benefits but who knows, I could be wrong.

 

I really just wanted to find out about this LT3045 to replace a LM317 within my Metrum Acoustics Pavane. First I have to measure how much current it uses to see if 500mA is sufficient. Texas Instruments TPS7A4700 even though offers up to 1A current wont work for me as the lowest working voltage output is 1.4 and I need 1.2. It's also noiser at 4.17µV.

[roberto2]

Would this one be good to replace the LM2940CT-5 on SU-1 internal power supply?

 

http://www.ebay.com/itm/LT3045-Ultralow-noise-0-8-VRMS-LDO-linear-regulators-0V-15V-0-5A-78xx-Layout-/252880467320?hash=item3ae0d9b578:g:jSMAAOSwol5YyCO1

[paulinus]

3 hours ago, roberto2 said:

Would this one be good to replace the LM2940CT-5 on SU-1 internal power supply?

IMHO, no, because PCB size of this LDO is 25x35mm. Replacement could be painful.

[roberto2]

1 hour ago, paulinus said:

IMHO, no, because PCB size of this LDO is 25x35mm. Replacement could be painful.

But I can read it is 15x25 mm

 

• PCB size: 15x25mm

[paulinus]

15 minutes ago, roberto2 said:

But I can read it is 15x25 mm

Yep, my fault! Choose wrong type. Even in this case it is hard to guarantee one-to-one swap (from mechanical point of view). E.g. LM2940CT-5 is TO-220, which is 10x15mm. 

[elan120]

6 hours ago, roberto2 said:

Would this one be good to replace the LM2940CT-5 on SU-1 internal power supply?

 

http://www.ebay.com/itm/LT3045-Ultralow-noise-0-8-VRMS-LDO-linear-regulators-0V-15V-0-5A-78xx-Layout-/252880467320?hash=item3ae0d9b578:g:jSMAAOSwol5YyCO1

This may not be a good direct replacement unit without a good heat sinking method due to high Vin and Vout differential at ~7.3V (Vin 12.3V - Vout 5V), which will drive the calculated junction temperature Tjmax slightly above 145C assuming output current (Iout) at 150mA, and this is higher than the spec limit of 125C.  If this regulator is to be used as is, may need to consider using a lower output step down transformer.

[roberto2]

1 hour ago, elan120 said:

This may not be a good direct replacement unit without a good heat sinking method due to high Vin and Vout differential at ~7.3V (Vin 12.3V - Vout 5V), which will drive the calculated junction temperature Tjmax slightly above 145C assuming output current (Iout) at 150mA, and this is higher than the spec limit of 125C.  If this regulator is to be used as is, may need to consider using a lower output step down transformer.

 

I thought Vin was 7V on the Talema transformer...

[elan120]

15 minutes ago, roberto2 said:

 

I thought Vin was 7V on the Talema transformer...

They connect the transformer in series, which drove the voltage up to 14V output before the bridge rectifier.  The 12.3VDC reading is a measured voltage from the unit I pulled from my SU-1.

[[email protected]]

1 hour ago, elan120 said:

This may not be a good direct replacement unit without a good heat sinking method due to high Vin and Vout differential at ~7.3V (Vin 12.3V - Vout 5V), which will drive the calculated junction temperature Tjmax slightly above 145C assuming output current (Iout) at 150mA, and this is higher than the spec limit of 125C.  If this regulator is to be used as is, may need to consider using a lower output step down transformer.

Hi
Just FYI - measured thermal resistance for reg board approx 70°C/W
In your case (Vin=12.3V, Vout=5V, Iout=0.15A dissipated power 1.1W 
If ambient temperature Tamb=45°C (but could be higher inside cabinet)

TJMAX = 45°C + 1.1Wx70°C/W = 122°C

 

with small heatsink (like https://www.aavid.com/products/standard/507302b00000g - fit just perfectly)

thermal resistance approx 54°C/W

 

All MLCC used are X7R (rated for 125C operation as well as tantalum cap)

 

BR Alex

 

 

[roberto2]

12 minutes ago, elan120 said:

They connect the transformer in series, which drove the voltage up to 14V output before the bridge rectifier.  The 12.3VDC reading is a measured voltage from the unit I pulled from my SU-1.

OK, so what regulator could replace the LM2940CT-5?

 

Belleson would be fine but shipping cost to Europe are just too expensive (33$!!)

 

[elan120]

10 minutes ago, [email protected] said:

Hi
Just FYI - measured thermal resistance for reg board approx 70°C/W
In your case (Vin=12.3V, Vout=5V, Iout=0.15A dissipated power 1.1W 
If ambient temperature Tamb=45°C (but could be higher inside cabinet)

TJMAX = 45°C + 1.1Wx70°C/W = 122°C

 

with small heatsink (like https://www.aavid.com/products/standard/507302b00000g - fit just perfectly)

thermal resistance approx 54°C/W

 

All MLCC used are X7R (rated for 125C operation as well as tantalum cap)

 

BR Alex

 

 

Hi @[email protected],

 

Good to see you dropping by here.  I am currently using your regulator in my SU-1 to send 5VDC to the main board with outstanding result, and is currently waiting for the 3.3V regulator that you just shipped last week to change out the Belleson regulator that I currently using to make a comparison between these two.

 

Regarding the calculated Tjmax, I was using the formula from the spec sheet, which turned out to be 1.16W, which is similar to your result.  As far as the ambient temperature goes, you are right, it will depend on what the user setup is that could have a lower junction temperature then what I quoted maximum Tjmax above.

Power Dissipation = IOUT(MAX) • (VIN(MAX) – VOUT) + IGND • VIN(MAX)

PDISS = 0.15A • (12.3V – 5.0V) + (0.005A • 12.3V) = 1.16W

 

One question about using the heat sink on your regulator, how well in terms of thermal transfer is your regulator using a heat sink such as what your link show?  I plan to use your regulator in other area where heat sink is needed, but not sure how well in thermal transfer is your regulator with the back side of PCB against heat sink with thermal compound in between.