High performance regulators for the Buffalo DAC and IVY

Builder Brad · « **Reply #80 on:** 6 Aug 2011, 10:23 am »

Cheers Paul,

I think that I will try using single + and - regs on the Legato i/v initially. The couple of `00 £ saved will go towards upgrading some of the critical resistors on the Legato board with Texas Components TX2575s. I also will then have an upgrade path with your regs that will almost be plug in - so long as I leave space in the case.

I need:

4 off Z7803v3 @ £30 each £120

1 off S1701v2 @ £36 £036

1 off PR3DC-05v4 @ £80 £080

Then the Legato 1/V regs

1 off PR3AC-15 @ £95 £95

1 off NR3AC-15 @ £95 £95

Total retail for all the regulators £426

Less 25% discount £106

Kit price TOTAL £320

PLUS CARRIAGE £10

I am going to use my 12v SLA battery to supply the main board and an 18-0-18 AC supply for the Legato regs.

how do I pay?

Cheers

Brad

Builder Brad · « **Reply #81 on:** 13 Aug 2011, 10:50 am »

Ok.

I have now ordered those regulators from Paul Hynes.

What other parts are worth upgrading on the main DAC board, or the Legato. Might as well get them ordered up while I am waiting for the Buffalo and Pauls regs.

I am already looking at Texas Component bulk foil TX2575s at 1k and 4.75k values on the Legato and the 22.1 ohm output resistor.

Brad

serengetiplains · « **Reply #82 on:** 14 Aug 2011, 02:14 pm »

The TX2575s are imo worth the price, Brad. Really good stuff.

rklein · « **Reply #83 on:** 22 Aug 2011, 01:00 pm »

I have finally placed my order with Paul for his regs for the Buff III board. I also opted for Paul's SR3-12 power supply with DC lead. I decided to opt for three TP BiPolar Placids for the Legato I/V to keep the cost of the DAC down. Really looking forward to this build.

Paul was absolutely first rate in answering all my questions.

Regards,

Randy

GordonJ · « **Reply #84 on:** 21 Sep 2011, 10:00 am »

Hi - Finally got around to picking up my regs from the post office depot this morning - it's been a very busy week. All looks good, thanks Paul!

Except - one question as I really don't want to mess up...

Pin out order on the S1701v2? On the 3V3 regs it's really clearly marked with I G O, but on my S1701 it's less clear - maybe my tired eyes - the only markings I can see on a quick scan look like I O O. Can anyone make this really clear and idiot-proof for me? (i.e. which side am I looking from, which way up is it and what is the sequence for the pins?)

Thanks

Gordon

Paul Hynes · « **Reply #85 on:** 21 Sep 2011, 11:41 am »

Hi Gordon,

The pin out on the S17 reads, on the track-side, from left to right, I for input, O for output and AG for ground. The A in AG refers to the adjustment terminal on 317 type regulators as the S17 regulator is used to replace LM317 pin out type regulators. The voltage setting components connected to the adjustment terminal with 317 type regulators are not used with the S17 and AG is just connected to ground. Others have commented on this so I will be dropping the A in AG on the next board run to avoid further confusion.

Regards
Paul

GordonJ · « **Reply #86 on:** 21 Sep 2011, 12:15 pm »

Thanks Paul! I'll have closer look at the board tonight but that is very clear and should enable even me to get it right!

All the best, Gordon

GordonJ · « **Reply #87 on:** 3 Oct 2011, 06:02 pm »

Hi Paul - Many thanks for your excellent products and for the support and advice. Finally got around to putting everything together today - worked first time and sounds fantastic. Built with full set of PH regs installed from the start so I can't compare with stock BII etc. but this is definitely the best DAC I've had in my sytem. Now to find a suitable case... Thanks again, All the best, Gordon

alch3my · « **Reply #88 on:** 12 Oct 2011, 01:26 pm »

Finally received my regulators. Here's a customary shot

BTW Paul, one of the 3v3 regulators is labelled "3v3 H? VDD". But the correct VDD regulator is the one that's labelled 1v2 with "S17LNS2" on the track side?

How is the PR3 supposed to be wired up?

Paul Hynes · « **Reply #89 on:** 13 Oct 2011, 03:24 pm »

Sorry, I have marked the 3v3 HP module wrongly. It should read DVCC. The S17 is for VDD.

The PR3 regulator module is wired as follows :-

http://i700.photobucket.com/albums/ww7/paulhynes/PR3PPRAP.jpg

The input voltage should be 6 to 9 vac and the dc output voltage can be set to suit via the trim pot. Ignore the postreg shown on the drawing and feed the PR3 0v and +ve out to 0v and VD on the Buffalo board.

Regards
Paul

alch3my · « **Reply #90 on:** 15 Oct 2011, 10:33 am »

Thank you, Paul.

Hmm just to confirm,

"2 off Z1703v3 shunt regulator for replacing LT1763-3v3 on DVCC" refers to "2 3.3V ... for the on board Oscillator (VDD_XO) and main digital sections of the ES9018 (DVCC)."

I have a question, there are 4 Z17 3.3V regulators. But if you look at the picture below.. one of them (the wrongly labelled module) has a different circuit from the other 3. I'm sure it isn't the same as the rest, right?
http://farm7.static.flickr.com/6166/6246130390_6536e8f92e_b.jpg

i understand that DVCC is 3v3

Paul Hynes · « **Reply #91 on:** 15 Oct 2011, 02:02 pm »

alch3my

To be clear, these are the new shunt reg modules that I had to revise recently, because of the world-wide component shortage for the current source chip I used to use with these regulators. The current source section is now split into three smaller current sources. This allows easy selection of output current for different applications. Using two current sources provides around 70ma and three current sources provides around 120ma. I also revised the pin out hole pattern, so the same module can be configured for replacing 317 type regs and 78 type regs, just by selecting where to fit the lead out wires. This saves stocking two separate PCB designs.

The wrongly labelled module has three current sources fitted and this is for replacing the LT1763-3v3 for DVCC. The other three 3v3 shunt regs are for VDD_XO and the two AVCC supplies.

Regards
Paul

alch3my · « **Reply #92 on:** 19 Oct 2011, 02:05 pm »

You're a great help as always, Paul!

Does the transformer VA rating matter? 50VA / 80VA?

Paul Hynes · « **Reply #93 on:** 25 Oct 2011, 10:53 am »

alch3my,

Sorry for the tardy reply. I missed your post about the transformers. I tend to go for oversized transformers so they are not operating at their full ratings. With this in mind I would personally use either 80 VA or even 160 VA.

Regards
Paul

alch3my · « **Reply #94 on:** 25 Oct 2011, 02:57 pm »

Thank you, Paul. I felt that posting my questions here rather than privately over email would be better so more people can learn from it, hope that's fine with you.

I read up on transformers and it seems like quite a few people believe that ei/r cores are better than toroids for PSU usage. What are your thoughts on this? You're definitely the most qualified person to ask!

Are split bobbin ei cores supposed to be better at rejecting noise from the mains? I came across these which seem to be looked upon favourably by john curl, and am thinking of trying them out. But the minimum output rating they have is a 10V and the PR3 takes a max of 9V.. i don't supposed this can be used then?
http://www.signaltransformer.com/content/split-bobbin-with-isolation

Paul Hynes · « **Reply #95 on:** 26 Oct 2011, 03:00 pm »

Alch3my,

I would prefer it if people posted their applications questions here as it forms a reference for others so this is fine with me. Just bare in mind that you may have to wait a little for a reply as I am very busy nowadays.

There are pros and cons for each of the transformer construction methods and the results will also depend on the quality of construction materials and the attention to detail during construction.

Split bobbin transformers have poorer flux linkage than toroidal transformers, which generates larger stray magnetic fields around the transformers. They also have larger iron losses, which generates more heat for a given VA rating. They do show better isolation from the mains than standard toroidals, however an inter-winding screen can be fitted to a toroidal transformer that will give good isolation from mains noise.

I have tried many transformers over the years and I prefer the toroidal type, but not the off the shelf types from the main electronics distributors. These are built to a very low price to remain competitive in a general electronics market and are often noisy mechanically, especially in the larger sizes. They are usually built with high flux density to allow the use of a smaller core size for a given VA rating and they suffer core saturation problems, particularly at switch-on, because of their high flux density construction. This reduces the transient headroom dramatically. Core saturation effects can be quite severe with these high flux density transformers and this can strangle the dynamic presentation of the sound system and collapse the sound stage, not to mention causing large amounts if inter-modulation on the mains supply. This is likely to be the main reason people reject toroidal transformers for audio. It’s a shame really because when they are designed properly they do give very fine performance.

Price plays a big part in performance and you will not get high-end performance from a beer budget transformer. For my higher performance audio grade power supplies I have low flux density transformers, wound on oversize cores, to my specification by Canterbury Windings in the UK. This is not the whole story of the specification as non-disclosure agreements are in place regarding some of the parameters, preventing me from public discussion. However I can say that the resulting transformer is quiet, both mechanically and electrically, and it does not suffer from the core saturation problems that typical “off the shelf” low cost transformers do. These transformers give much better sound quality than any of the “off the shelf” transformers I have tried.

I hope this helps.

Regards
Paul

alch3my · « **Reply #96 on:** 28 Oct 2011, 12:41 am »

Thank you, Paul.

Will there be any problems if i use a 10V AC center tap transformer for the PR3? I know they only take 6-9VAC, so will that extra 1V do any harm? Hmm since it is impossible for me to get the same custom toroids that you get, are there any off-the-shelf and readily available brands that aren't *so* bad?

Paul Hynes · « **Reply #97 on:** 31 Oct 2011, 05:07 pm »

Alch3my,

10 vac is fine as long as you ensure the PR3 copper mounting bracket is mounted on a metal chassis or heatsink rated at 4 degrees C per watt or better.

Noratel transformers are inexpensive and may be available in your area. They are the best “off the shelf” ones I have found so far but certainly not in the same league as the Canterbury Windings transformers.

Regards
Paul

Builder Brad · « **Reply #98 on:** 2 Nov 2011, 06:19 pm »

Hi Paul,

I just received my regulators - they look fantastic and I am now working them into my case and adding them to my Buffalo DAC.

I have a question about the + and - 15v regulators for the Leggato i/v board:

I have an 18-0-18v transformer and have tied the center tap, so that I have 3 wires that supply 18-0-18v. I am strugling with using this scheme to wire up the 2 x regulators as they do not seem to like the shared 0v wire on the AV supply - this does not present a problem when I just connect the AC power, however when I connect the DC 0v outputs together my transformer starts to get very hot and I am measuring 40+V DC between the + and - DC outputs and over 20v = and - relative to 0v.

Do i need to power the AC inputs independently and then tie the DC 0v together?, or am i doing something else wrong?

on the actual regulators the outputs appear to be marked round the wrong way - 0v is marked on the inside pin of the twin terminal when my DMM indicates that 0v is on the outside pin - is this correct?

Brad

Paul Hynes · « **Reply #99 on:** 3 Nov 2011, 10:40 am »

Hi Brad,

Each of the PR3-15 regulators requires it’s own independent AC supply. Either via separate windings on one transformer, or separate transformers. The 0v connection from the DC out terminals is then wired to signal 0v at the load. Everything should read correctly once this is done unless components on the modules and/or the transformer have been damaged thermally by the way you wired the modules.

Regards
Paul