High performance regulators for the Buffalo DAC and IVY

richidoo · « **Reply #60 on:** 5 Jul 2011, 03:05 am »

Getting ready to order some regulators for my Buff2 kit. I heard a Buff32 with modified series power supplies and output stage mods and it blew away my stock Buffalo32 with LCDPS power supplies. The power supplies make a huge difference in dynamics, clarity and intensity. So now I gotta build up my Buff2 to get some of that goodness.

Some quick questions:
Multibit's post mentions the necessity to cross the adjust and output pins on Z17** regs. But closeups of his DAC show straight pins on the regulators. Maybe he got Z7803v3 regs or maybe the pins don't need to cross anymore? Paul, can you please confirm that the Z1703v3 regs included your Buffalo2 kit will drop into Buffalo2 AVcc? Thanks

There are 4 holes for the AVcc power supply bypass. VD, Gnd, AVcc and DVcc. I assume we ignore the DVcc hole?

Paul, just curious, why do you provide a high power version of your Z1703v3 reg. for the digital supplies? The ESS9018 spec sheet says DVcc are 3.3V@7mA (x2 for top and bottom), Vdd (core) 1.2V@37mA, and AVcc 3.3V@25mA. I'm sure your standard Z17**s can make 50mA easily, why aren't they plenty good enough? Thanks

Does anybody know what VDD_XO powers? It is not mentioned in the 9018 spec sheet, so maybe it is something on the board? TP site says the oscillator has it's own dedicated power supply, is that VDD_XO?

I have some Placid shunt power supplies. Are these adequate for the DVcc and VDD? I would think these are a more constant load than the AVcc which will obviously benefit from PH regulators. I suppose I could use the TP Placid for VD 5.5V supply also. Is the speed of a PH regulator needed for Vd pre reg sitting 2V above final voltage? Paul mentioned a reg kit for battery power, I think the Placid is faster and lower impedance than a battery. Just thinking out loud, trying to save some money if possible. But the whole kit is very tempting, especially with the great feedback you guys are giving.
Thanks for any insights/opinions!!
Rich

Paul Hynes · « **Reply #61 on:** 5 Jul 2011, 12:59 pm »

Hi Rich,

The error amplifiers I use in the 3v3 shunt regs are just over 2000 times faster with a bandwidth 50 times wider than the LMP7732 used in the Trident and the early Placid that uses this chip. This high speed is required for high quality performance when dealing with load current swings clocked at multi-MHz frequencies. This is one of the reasons you heard a very noticeable improvement with the high-speed regulators.

I now supply the Z7803v3 for the Buffalo II regulator upgrades, as this board is pin compatible without bending the regulator leads. The circuit is identical to the Z1703v3.

There are 4 holes for the AVcc power supply bypass. VD, Gnd, AVcc and DVcc. Ignore the DVcc hole.

I have seen some conflicting information regarding current draw for the Buffalo dacs and some have reported regulator dropout if the shunt current is set too low. Remember that the set current minus the regulator section operating current is the maximum current available from a shunt regulator. If you try to draw more the regulator will drop out of regulation. Digital circuit current draw increases from idle, when processing data, and as the clock frequency used in the Buffalo II is 80MHz, you would need some specialist equipment to measure the transient current requirements. So in the Buffalo II the current draw is not fixed and will depend on the level of processing being used in the Sabre chip. The standard Z17/Z78 will typically supply around 60 ma with the standard current source. This seems fine for AVCC but I like to ensure that there is more than enough current available for correct regulation under all operating conditions with the digital circuitry. The HP version of the Z1703v3 and the Z7803v3 can provide 120ma to allow headroom for DVCC and VDD_CC.

The VDD_XO supply is for the crystal oscillator module.

Check out the open loop frequency response of the LMP7732 error amplifier (used in the early Placid and the Trident regulators) in the National Semiconductor datasheet. It shows a falling response with frequency – approx, 88dB at 1KHz, 68 dB at 10 KHz, 48dB at 100KHz, 28dB at 1 MHz, 8dB at 10MHz, 0dB at 20MHz. This corresponds to a reduced regulation capability with rising frequency where the error amplifier actually stops working at 20MHz. This is also going to allow the supply line rejection to reduce at the same rate. Once the regulator stops working it’s line rejection capability will also cease. The Placid HD supply may do better than this but I would be surprised if it reached the 1GHz response limit of the Z regs error amplifier. You could use the Placid for the VD5v5 supply but even here people are reporting improvements using the Z1P or the PR3 regulator modules instead of Placid. The Z1P-5v5 error amplifier bandwidth is 1GHz like the mini shunt regs and the PR3 error amplifier bandwidth is 100MHz.

Battery operation is possible and the 5v5 VD pre-reg (a DC input version of the PR3 is available) and both the Z1P-05v5 and the PR3-05v5 can be powered from any voltage from 11 volts to 18 volts. This will give the benefit of no mains interference to the Buffalo II power feed although you will have to consider battery management requirements and maintain a good charge on the batteries for consistent performance especially if the load current draw is high. Battery life may also be an important consideration, depending on which battery type you use. Like anything there are pros and cons here and a well-specified, battery based, power supply can be more expensive to implement than a good mains supply.

Regards
Paul

richidoo · « **Reply #62 on:** 5 Jul 2011, 02:11 pm »

Thank you for the immediate and thorough response. Perhaps the best technical answer I have ever received from an audio seller! Except for the other emails I've gotten from you.

I do have a spare Optima red top car battery and a smart charger that I used with my Altmann DAC and amp once a upon a time. I will PM you today about ordering the Buffalo 2 PS kit.

Thanks again Paul!
Rich

Paul Hynes · « **Reply #63 on:** 5 Jul 2011, 02:45 pm »

Hi Rich,

Your welcome.

The Red Top will do fine. I am currently using spiral wound gel batteries for the master supply for my Altmann DAC and this works very well as a master supply with high quality regulation feeding the equipment circuitry. I am not so keen on direct connection of batteries to the Altmann, or indeed other pieces of equipment I have tried this with, as the bass end is too loose and bloated for my taste. With the regulators it is a completely different presentation that is well balanced throughout the audio frequency spectrum and with no annoying bass anomalies.

Regards
Paul

richidoo · « **Reply #64 on:** 5 Jul 2011, 03:08 pm »

Good to know, thanks. The impedance of battery is so high compared to a good regulator. This biggest impact I noticed in Buff32 with improved power supplies was the dynamic impact of the bass. But the treble was also clearer and more "intense."

I am not yet sure If I want to bother with battery, since my amps run an AC anyway. But if I were to use a DC input regulator, which is preferred, Z1P or PR3 (dc). Z1P has higher bandwidth, seems like the way to go? Thanks
Rich

Paul Hynes · « **Reply #65 on:** 5 Jul 2011, 04:05 pm »

Hi Rich,

The Z1P sould be better regarding bandwidth, but this is not the whole story. According to all reports the PR3 is giving a more musical presentation as the pre-regulator. I am also finding this with equipment when I have used it as a master power supply.

The prefered choice, which has been generally confirmed by my experiments, is the high-speed shunt regs for digital circuitry and the PR3 for master power supply duties, low noise analogue circuitry and high power supplies. The PR3 may not have the bandwidth of the Z1P but it is a fast regulator and it is very quiet too, measuring on a HP3561A Spectrum analyser around 35 nanovolts root Hz at the output with the shunt reg measuring around 220 nanovolts root Hz. For comparison purposes the ALW low noise series reg measured 70 nanovolts root Hz. The loading requirements for the pre-reg are relatively benign as the on board Buffalo shunt regulators present a constant current load. The supply line rejection of the PR3 is less than the Z1P but still very good. The PR3 has an output voltage adjustment pot for convenience.

I think, on balance I would have to recommend the PR3 for the pre reg.

Regards
Paul

richidoo · « **Reply #66 on:** 5 Jul 2011, 05:32 pm »

FYI, The crystal oscillator spec sheet:
http://www.crystekcrystals.com/crystal/spec-sheets/clock/CCHD-950.pdf
3.3VDC (+/-0.3V) @ 15mA nominal, 25mA max

Paul Hynes · « **Reply #67 on:** 9 Jul 2011, 10:40 am »

Rich,

Sorry about my tardy reply. I have been exceptionally busy this week. Point taken about the crystal oscillator supply, you could use either the standard or the HP to power this. Several customers have asked for more current for the oscillator supply but did not give a reason. Maybe they were experimenting with alternative clock oscillators.

Regards
Paul

Builder Brad · « **Reply #68 on:** 2 Aug 2011, 12:59 pm »

Hi Paul,

I am looking at placing an order for the new Buffalo MK3 when the next pre-order opportunity goes live - 3 days time I think.

I was originally looking at ordering the DAC with the Legato I/V, 3 x Placid BP power supplies for the i/V, Trident regulators and 1 x Placid PS for the main DAC, however I really want to use the best Power supply regulation that I can right at the beginning of the project.

I will be running the DAC from DC battery power, having 4x20VA 12v SLA batteries that were previously used to run a TDA1541 DAC. I can configure the batteries in various series and parallel combination as I have independent chargers and load balancing options.

can you provide me with a complete package price, for the supply of what you consider to be the best of your regulators and PS modules for the Buffalo DAC, with DC input power?

cheers

Brad

Paul Hynes · « **Reply #69 on:** 2 Aug 2011, 02:56 pm »

Hi Brad,

I will quote the normal prices I charge for regulators initially but you can deduct 25% off these prices to arrive at the kit price

Firstly the Buffalo III regs

4 off Z7803v3 @ £30 each £120

1 off S1701v2 @ £36 £036

1 off PR3DC-05v4 @ £80 £080

Then the Legato 1/V regs

3 off PR3DC-15 @ £80 £240

3 off NR3Dc-15 @ £80 £240

Total retail for all the regulators £716

Less 25% discount £179

Kit price £537

Insured carriage and packing will be £25 to the USA

I would suggest that you use one 12 v battery by itself for the Buff III and two stacked 12v batteries per rail giving +/- 24v for the Legato I/V.

Regards
Paul

Builder Brad · « **Reply #70 on:** 2 Aug 2011, 05:18 pm »

cheers Paul,

I am in the UK, so could collect.

on the Legato PS do you mean -24 0 +24 DC?

Brad

Paul Hynes · « **Reply #71 on:** 2 Aug 2011, 05:43 pm »

Hi Brad,

You are welcome to collect but do you know how far out I live from the mainland? The trip to South Uist is a very long and expensive trip. Fortunately the easiest way is to just post the modules via insured Special Delivery and this costs £10.

I mean –24 0 +24 to feed the I/V regs.

Regards
Paul

Builder Brad · « **Reply #72 on:** 2 Aug 2011, 05:52 pm »

cheers Paul,

sorry more questions...

are the regs for the Legato individual + and - versions of the NR3DCs? do you have dimensions of the individual regs please?

Is the Legato good enough to justify 3 x + and - regulation?

Brad

Paul Hynes · « **Reply #73 on:** 2 Aug 2011, 06:12 pm »

Hi Brad,

I do not have a Legato. Some constructors who have separated the regulation to Legato have told me that the effort is worthwhile. Is there anyone out there who has done this prepared to post their results as feedback for others?

The regs for the Legato are individual modules. The PR3 is the positive voltage version and the NR3 is the negative voltage version.

The modules measure 48mm x 48mm with a maximum height above board of 25mm.

Here is a photo of the PR3DC module :-

http://i700.photobucket.com/albums/ww7/paulhynes/PR3iDC004.jpg

Regards
Paul

Builder Brad · « **Reply #74 on:** 2 Aug 2011, 06:38 pm »

cheers Paul,

I will probably need to stack those regulators as they are going to easily take up more space than the DAC alone.

is it possible to set the regs up to give +/-18, or even 20v? It seems like a big drop to go from the 24v on each battery bank to 15v. I guess that even with the higher output voltages I will then pay the price in extra dissipation heat from the Legato.

Brad

NicMac · « **Reply #75 on:** 2 Aug 2011, 06:44 pm »

Brad,
don't exceed 15V for the Legato. It runs pretty borderline hot at this rail voltage.
The heat generated by the Legato is produced by resistors that are difficult to sink.
Cheers,
Nic

Builder Brad · « **Reply #76 on:** 3 Aug 2011, 10:16 am »

Cheers Nic,

I thought as much.

Paul,

The Buffalo DAC will be sharing a case with my pre-amp/buffer.

I already have an 18-0-18v 50VA transformer in the pre-amp case powering a Salas DCB1 Buffer - I may use this to power the 6 regulators for the i/v stage - do I need a different type of reg for AC input?

will probably only use the batteries for the 12v DC supply to the main DAC regulators.

are the i/v regulators the only ones that need to be fitted on stand-offs, with the remainder being plug in modules on the main PCB?

Brad

rklein · « **Reply #77 on:** 3 Aug 2011, 02:11 pm »

If one was to choose just one of your kits, which kit would have more of a positive impact? The kit for the Buffalo III or the kit for the Legato 3.1 I/V stage?

Thanks,

Randy

Paul Hynes · « **Reply #78 on:** 3 Aug 2011, 02:47 pm »

Brad,

For transformer input you would need the PR3AC input version which uses Schottky Barrier rectification and Panasonic low ESR energy storage. This will add £15 to each PR3 after the 25% discount is applied.

The PR3 regulators for the I/V stage do not need standoffs. The copper mounting bracket on the PR3 is used for mounting the module. This is isolated from the regulator circuitry so all you have to do is bolt it to the chassis.

Randy,

I would go for the Buffalo regs in preference as the Sabre Dac chip is rather sensitive to power supply quality.

Regards
Paul

rklein · « **Reply #79 on:** 3 Aug 2011, 02:49 pm »

Thanks Paul.