The true experimental tweak thread

[lmitche]

I did some sleuthing and the Sigma 11 should work with your 15 volt ac transformer Just get one set for 11 or 12 volts dc output and run into Michaels boards.

[Cornan]

9 minutes ago, lmitche said:

I did some sleuthing and the Sigma 11 should work with your 15 volt ac transformer Just get one set for 11 or 12 volts dc output and run into Michaels boards.

 

Great! Thanks for trying that out for me Larry. Much appreciated! I will go ahead and order a S12 right now! ???

[marce]

2 hours ago, Cornan said:

I’ll guess these are the sorts of challenges an EE would face on a daily basis. I’ll bet they’ll laugh their heads off reading this challenge! ?

 

@Speedskater & @marce where are you? I could use a little support here! ?

All mains fluctuates in voltage, depending on where you live, nearby loads... the list is endless, add powerline communication, internal loads, nearby loads, etc. Filtering and over-voltage protection can help with the incoming mains, brown outs (Dips in voltage, in the UK there are dips after soap operas as everyone puts the kettle on, less now there is catch up TV.) are down to the relevant PSU and how it holds up. To determine how bad your mains is you have to monitor it for quite a while, not easy without the right kit, and that's not cheep to even hire. Then you have to realise most components are made to cover a large market, the demand for lower cost products and the requirements for lower power consumption (regulations on PSU efficiency, not the best idea as running a SMPS at peak efficiency and low noise requires the optimum components, this cost money... compromises are made and efficiency requirements are met, the net loss is a slight increase in overall noise, add the numerous cheep phone chargers etc. plugged almost constantly and you don't laugh.

[look&listen]

8 hours ago, Cornan said:

Another important thing that I forgot to say is that due to the AC-AC PSs balanced & floating design I am actually quite comfortable to try it out connected directly to the AC mains wall outlet (maybe via a DC blocker trap filter though) instead of via the balanced & floating IT. That could have a bunch of positive effects to SQ as well if that holds true.

Combine isolation transformer and step-down transformer in one box for one PSU is interesting packaging choice. Not efficient but that common in audiophile gear anyway. Maybe great, maybe not but good experiment  (implementation rules as always).

[Cornan]

8 minutes ago, marce said:

All mains fluctuates in voltage, depending on where you live, nearby loads... the list is endless, add powerline communication, internal loads, nearby loads, etc. Filtering and over-voltage protection can help with the incoming mains, brown outs (Dips in voltage, in the UK there are dips after soap operas as everyone puts the kettle on, less now there is catch up TV.) are down to the relevant PSU and how it holds up. To determine how bad your mains is you have to monitor it for quite a while, not easy without the right kit, and that's not cheep to even hire. Then you have to realise most components are made to cover a large market, the demand for lower cost products and the requirements for lower power consumption (regulations on PSU efficiency, not the best idea as running a SMPS at peak efficiency and low noise requires the optimum components, this cost money... compromises are made and efficiency requirements are met, the net loss is a slight increase in overall noise, add the numerous cheep phone chargers etc. plugged almost constantly and you don't laugh.

 

Not completely sure how that helps me to solve my 15VAC to 20VDC issue, but interesting non-the-less! ?

[sandyk]

9 hours ago, Cornan said:

Do you know of any other 5A pre regulators that might suits the purpose of getting the 15VAC down to 16VDC?

 

 All of them ?

Unless your 15VAC output is tightly regulated, it is likely to be a little higher with a light load. Even with an accurate 15VAC, the voltage across the Input filter capacitors is likely to be close to 21.5V under relatively low loading !!! 

Use low voltage drop Schottky rectifier diodes and you will increase the leeway when it is fully loaded.

[Cornan]

5 minutes ago, look&listen said:

Combine isolation transformer and power supply step-down transformer in one box for one PSU is interesting packaging choice. Not efficient but that common in audiophile gear anyway. Maybe great, maybe not but good experiment  (implementation rules as always).

 

Real life trials will tell if that holds true or not. I would like to think it would, but are not confident until I know for sure, The balanced & floating IT is still my best hifi related purchase ever! ?

[look&listen]

2 minutes ago, Cornan said:

The balanced & floating IT is still my best hifi related purchase ever!

Have you measured output AC volts?

[Cornan]

8 minutes ago, sandyk said:

 

 All of them ?

Unless your 15VAC output is tightly regulated, it is likely to be a little higher with a light load. Even with an accurate 15VAC, the voltage across the Input filter capacitors is likely to be close to 21.5V under relatively low loading !!! 

Use low voltage drop Schottky rectifier diodes and you will increase the leeway when it is fully loaded.

Thanks! Not sure what increased leeway means though? My problem is that LT1084 requires a 2v drop from AC to DC. This means AFAIK that 15VAC equals 13VDC at output.

Anyhow the S12 recommended by Larry is on order. Hopefully it will be my saviour! ?

[Cornan]

1 minute ago, look&listen said:

Have you measured output AC volts?

No, not yet. I suppose it is correct.

[look&listen]

1 minute ago, Cornan said:

No, not yet. I suppose it is correct.

ASSUME?

No, measure to know for sure. Will be unloaded, but still data. Maybe not as bad as you worry.

[sandyk]

7 minutes ago, Cornan said:

Thanks! Not sure what increased leeway means though? My problem is that LT1084 requires a 2v drop from AC to DC. This means AFAIK that 15VAC equals 13VDC at output.

 You require only  16V DC ?

 With 15VAC and a bridge rectifier into suitable filter capacitors you will obtain close to 21.5V to play with !  (15V A.C. x 1.414)  Under load, you need to take into account the voltage drops of the rectifier diodes.

[Cornan]

Just now, look&listen said:

ASSUME?

No, measure to know for sure. Will be unloaded, but still data. Maybe not as bad as you worry.

 

I am a AC newbe! ? I’ll get my things together and measure the AC outpute voltage tommorow. Thanks for the pointer! ?

[Cornan]

1 minute ago, sandyk said:

 You require only  16V DC ?

 With 15VAC and a bridge rectifier into suitable filter capacitors you will obtain close to 21.5V to play with !

 

That’s the problem. My HC-HPULN just coop with 20VDC, not more! ?

[sandyk]

9 minutes ago, Cornan said:

 

That’s the problem. My HC-HPULN just coop with 20VDC, not more! ?

 WTF is a an  HC-HPULN ? Does it have an A.C. input or only a DC Input?

 Can you provide a link to further information about it ?

A Google search for HC-HPULN gave no results.

[Cornan]

15 minutes ago, sandyk said:

 WTF is a an  HC-HPULN ? Does it have an A.C. input or only a DC Input?

 Can you provide a link to further information about it ?

A Google search for HC-HPULN gave no results.

 

No links available since it is still not an official release yet. It is the same one as Stammheims 3A LT3045 boards, but 5A and with Kemet A750 output caps. It is a AC-DC PS board that I use in series.

[lmitche]

35 minutes ago, Cornan said:

 

No links available since it is still not an official release yet. It is the same one as Stammheims 3A LT3045 boards, but 5A and with Kemet A750 output caps. It is a AC-DC PS board that I use in series.

Yes, but in this case the sigma 11 will do the AC to DC conversion and the two hc-hpuln boards will be using DC on their inputs.

[lmitche]

1 hour ago, lmitche said:

I did some sleuthing and the Sigma 11 should work with your 15 volt ac transformer Just get one set for 11 or 12 volts dc output and run into Michaels boards.

Cornan,

 

How much voltage did you want to get out of the two Stammheim boards?

 

Larry

[sandyk]

53 minutes ago, Cornan said:

 

No links available since it is still not an official release yet. It is the same one as Stammheims 3A LT3045 boards, but 5A and with Kemet A750 output caps. It is a AC-DC PS board that I use in series.

 

If it uses onboard rectification, the 21.5V DC into it (Instead of A.C.) would be further reduced by the voltage drops of the 2 conducting onboard diodes, assuming it uses a bridge rectifier. This would also give further filtering.

[Hauser]

Hi Cornan,

 

Since you are ordering a Sigma 12 (11) regulator, the AMB site has recommendations for suitable sized transformers in the parts list section for the S11.  It suggests a 15VAC output trans for 12VDC output after regulation through the S11.  As has already been mentioned though, this does requires quite a lot of power(heat) to be dissipated.  As you want 12VDC after the LT3045, this will require a couple of volts so output after S11 should be 14VDC.

 

Martin.

[Cornan]

9 hours ago, lmitche said:

Yes, but in this case the sigma 11 will do the AC to DC conversion and the two hc-hpuln boards will be using DC on their inputs.

 

Yes, the Sigma 12 is my best option so far. My initial plan will be to attach it to the heatsink side of the AC-AC PS and run the output wires to the PS output socket giving it 14VDC out. The two HC-HPULNs (14v>13v & 13v>12v) will be external as I want them to be.

Anyway, I am still open for other suggestions to bring the 15VAC up or down a couple of volts if possible.

[Cornan]

9 hours ago, lmitche said:

Cornan,

 

How much voltage did you want to get out of the two Stammheim boards?

 

Larry

See my previous post.

[Cornan]

8 hours ago, sandyk said:

 

If it uses onboard rectification, the 21.5V DC into it (Instead of A.C.) would be further reduced by the voltage drops of the 2 conducting onboard diodes, assuming it uses a bridge rectifier. This would also give further filtering.

 

Yes, but it is still 20,81VDC which is 0,82 VDC too much for the first HC-HPULN. That’s why Sigma 12 is now on order thanks to @lmitche.

[Cornan]

2 hours ago, Hauser said:

Hi Cornan,

 

Since you are ordering a Sigma 12 (11) regulator, the AMB site has recommendations for suitable sized transformers in the parts list section for the S11.  It suggests a 15VAC output trans for 12VDC output after regulation through the S11.  As has already been mentioned though, this does requires quite a lot of power(heat) to be dissipated.  As you want 12VDC after the LT3045, this will require a couple of volts so output after S11 should be 14VDC.

 

Martin.

 

Thanks Martin! ?

This is exactly how I plan to do. I will attach the Sigma 12 on the heatsink side inside the AC-AC PS, so it will actually be a sort of balanced Sigma 11 LPSU with 14VDC output. The rating of the AC-AC PS is 50VA.

Do you have a link to that AMB site BTW? ?

 

Here is how the whole LPSU chain will look right now:

 

50VA balanced & floating AC-AC PS 15VAC> Sigma 12 14VDC> HC-HPULN 13VDC> HC-HPULN 12VDC> Brooklyn DAC

[sandyk]

14 minutes ago, Cornan said:

 

Yes, but it is still 20,81VDC which is 0,82 VDC too much for the first HC-HPULN. That’s why Sigma 12 is now on order thanks to @lmitche.

 

 I said 2 conducting diodes, which would mean around 1.5V less. If you used 1N5404 3A diodes etc. this would then mean around 2V less.

 BTW, when I stated around 21.5V across the filter capacitors , that was with only a very light load, or no load.