Quick check RE: Murata regulator replacement for Caiman?

[Gazjam]

Just a sanity check before I get the replacements I need.

Finding a "whistling" noise in the background, due to oscilation or summit with the Gator board / Murata regs...some research shows its probably the Murata switching noise being put into the audible range by the more open window of the Gator board - at least in my system.

So..
looking to replace the Murata's...
Sold on the Paul Hynes regs (Leo says they are the best he's used) here:
http://www.paulhynesdesign.com/page6.html

Have a linear supply with the Caiman so perhaps dont need to change both the 5v and 12v..?

Just a quick check as to what Paul Hynes Reg I'd need to replace the ones in the Caiman

...and do I need to replace them both?
I have a memory banging about in my bonce that I only need to replace one of them..if so what one?


Thanks! :cool:

[chrism]

Why not just build two linear supplies - one that can deliver 5v for the DAC chip and a 12 v one that feeds to the 12v reg position?

Are the Paul Haynes still switching type regs?

Regards

Chris

[leo]

Why not just build two linear supplies - one that can deliver 5v for the DAC chip and a 12 v one that feeds to the 12v reg position?

Are the Paul Haynes still switching type regs?

Regards

Chris

Are the Paul Haynes still switching type regs?

Go and wash your mouth out with soap :lolsign: (just joking)
Paul designs both series and shunt regs, after trying many different types of regulation his are by far the best I've tried. I've not tried them in the Caiman yet but I'd imagine they work great in there if the results are anything like when used in my BII dac.

Hi Gaz,
You could PM Paul , he may have had customers who's already tried the regs in a Caiman or 7520 already :) if you can afford it I'd personally replace both regs but if not , I'd go with the one causing you the problem which seems to be the 12v one?

[StanleyB]

I have been playing around with a couple of regulator designs and Gator mods of late, and with good results IMO. A AoS member brought his HD800 headphones and GS headamp to try out and compare. I'll see when I have time to write out instructions on how to duplicate my results.

[Gazjam]

Good stuff Stan, look forward to hearing your results...

[Gazjam]

Why not just build two linear supplies - one that can deliver 5v for the DAC chip and a 12 v one that feeds to the 12v reg position?

Are the Paul Haynes still switching type regs?

Regards

Chris

Sounds good but WAAY to hardcore DIY for me...I think? :scratch:

[Psion770]

I have lived with a fully modified Paul Hynes SR3 PSU and some of Pauls digital shunt regulators for my Caiman for some six months counting the investment and wait time and money well extremley well spent.
Revelations in pace rhythmn and timing and space and depth were the most obvious Dr Jimmy Dripps had a brief listen whildt citing my gator board and
some Elna caps and although a brief exposure could hear a marked difference.

I have continued To be impressed as have some of my friends who are real musicians who understand musicality tone etc.

Gazjam I am more than happy to demonstrate same here in Glasgow or over at Motherwell with the aid of a dram........

Psion 770

[Gazjam]

deciding to go with the Dexa's over the Paul Hynes.
Thanks anyway for the offer Martyn.

With Paul's there is a large VDrop and he recommends an 18v psu.
Sure they are fanatastic, but the psu I have goes to a smidge under 16V...cest la vie.

hoping to say goodby to my whistling Dac soon. :)

Actually, I heard my Dac in a another system recently and compared to a Musical Fidelity M1.
As well as the whistle from my Caiman the volume was considerable lower....I'm sure this is another side effect of the shonky regulator, so my Dac should sound quite "different" when I get it sorted.

[chrism]

I am still contemplating that the whistling noise may be due to the 12v Murata not getting sufficient headroom or voltage drop across it. If your PSU is set at say 15v the actual voltage in front of the Murata may only be close to 14v leaving a quite small 2v differential.

Most regulators appear to like a little more.

Regards

[maniac]

I am still contemplating that the whistling noise may be due to the 12v Murata not getting sufficient headroom or voltage drop across it. If your PSU is set at say 15v the actual voltage in front of the Murata may only be close to 14v leaving a quite small 2v differential.

Most regulators appear to like a little more.

Regards

Hi Chris, my laboratory linear PSU goes to 15.36V and even on this voltage the whistling is there. If I remember correctly the data sheet of 12V Murata this headroom should be OK. Anyways if I would like to go to higher voltage then the 10k 16V big cap would need to be replaced by something what can survive that voltage and then replace PSU which can go higher than those 15.36V.. Seems that I'll wait on report that Dexa newClassD solve the whistling even with using 15V PSU and then go for Dexas :)
BTW I'm not sure if only 12V Murata has to be replaced, if I remember correctly, even touching the 5V Murata changed the whistle frequency so possibly both has to be replaced - I would be interested if my assumption is correct :)

[chrism]

Hi Maniac,

I think that most people are setting the PSU without load.

Remember that you have a diode and a few tappings from the 15.3v voltage you have set the PSU at (and the 15.36v will be without load). I think that if you have the PSU connected and the DAC powered up and then read the voltage directly in front of the 12v reg I bet that you are well below the 15.36v you set. You may have to turn the PSU up to achieve say 14v at the reg.

Regards

[Canetoad]

Hi Chris, my laboratory linear PSU goes to 15.36V and even on this voltage the whistling is there. If I remember correctly the data sheet of 12V Murata this headroom should be OK. Anyways if I would like to go to higher voltage then the 10k 16V big cap would need to be replaced by something what can survive that voltage and then replace PSU which can go higher than those 15.36V.. Seems that I'll wait on report that Dexa newClassD solve the whistling even with using 15V PSU and then go for Dexas :)
BTW I'm not sure if only 12V Murata has to be replaced, if I remember correctly, even touching the 5V Murata changed the whistle frequency so possibly both has to be replaced - I would be interested if my assumption is correct :)

Tomas, I'm running mine using a Maplins linear PSU which is putting out about 15.1 Volts (no load) and I have no noise coming from my Caiman with the Dexas fitted. I'm going to replace it with a home made version set to just under 16 volts.

[chrism]

If your linear PSU has a decent smoothing cap say 10,000uf you can take out the one in the Caiman as it is rated at 16v. If you are worried about RF you could just use a small cap or tant rated at 25v say.

Not certain about the rating of the Gator as I don't use one (stayed with the passive mod). I think, but not sure, that the Gator takes an unregulated feed from near the input cap.

I still think that a dedecated 5v linear PSU inleau of the superreg is the way to go.

Regards

[Gazjam]

My linear PSU has smoothing and I removed the big cap in my Dac and replaced it with a 25v Oscon.
Well, I HAD to after the big cap burst!

Just ordered a set of the Dexa regs...HOPEFULLY this will be the end of my whistling dac!

[Canetoad]

I hope so Gaz. Good Luck! :)

What PSU are you using now?

[Gazjam]

Hi Bernie,

I'm using one of THESE hooked up with a meter of Mark Grants mains cable.
http://www.tdk-lambda.com/products/sps/ps_unit/nns/indexe.html

NNS15-15 15V 1.4A 21W

You can set the voltage +-10%, so just a smidge under 16v into my Dac.
Good step up from the standard one, very clean, low ripple.

Oh, got the regulators at 20% discount, emailed to ask first and I got through to the boss!
That said, had to order via web which put it through at $39 each..so $90 all in - still got the discount to be applied.

Still cheaper than elsewhere, even at this price.

[Canetoad]

Gaz,

They should e-mail you a PDF invoice with the discount applied. Should end up being around $73 US including postage if they've given you the discount.

Thanks for the details on the PSU. I'll see how I get on with the one I'm going to put together. At some point maybe we could do a comparison between the Maplins, yours and mine. :eyebrows:

[HighFidelityGuy]

On the subject of the 12V Murata reg possibly not getting enough head room; I've swapped the Caiman's reservoir cap for a 35V film version, removed the input diode, removed the resistor behind the 5V reg and set my linear supply's output voltage to 16V with the load attached. So I know that both regs are getting 16V, which is well above their drop-out voltage. Despite all that I still get hiss and whistling. So we can safely rule out the theory of the Murata regs not getting enough voltage. :)

The issue seems to be caused by the way the PSU, Murrata regs and Gator board interact with each other.

Is anyone having the noise issues with the Murata regs and Gator while using the original 15V Caiman supply?

[Gazjam]

Gaz,

They should e-mail you a PDF invoice with the discount applied. Should end up being around $73 US including postage if they've given you the discount.

Thanks for the details on the PSU. I'll see how I get on with the one I'm going to put together. At some point maybe we could do a comparison between the Maplins, yours and mine. :eyebrows:

Hey Bernie...

what I've had from them is an email Titled "Your Receipt Order Number: xxxxx" which breaks down the cost showing both regs at $39.95 each + Tax@ $10.39, totalling $90.29

I'm guessing this is just to acknowledge the order and not the final invoice?
Sure it wont be a problem though :)

*EDIT*
Recent email: "The discount will be applied once we enter the order in and then you will receive an order confirmation from one of our sales administrators. "

Speaking of which,
we should compare dacs at some point - always nice to say howdy. :cool:

[chrism]

On the subject of the 12V Murata reg possibly not getting enough head room; I've swapped the Caiman's reservoir cap for a 35V film version, removed the input diode, removed the resistor behind the 5V reg and set my linear supply's output voltage to 16V with the load attached. So I know that both regs are getting 16V, which is well above their drop-out voltage. Despite all that I still get hiss and whistling. So we can safely rule out the theory of the Murata regs not getting enough voltage. :)



What voltage are you reading at the 12v regulator (pin in) with the DAC powered up?

Regards

Chris

[Gazjam]

On the subject of the 12V Murata reg possibly not getting enough head room; I've swapped the Caiman's reservoir cap for a 35V film version, removed the input diode, removed the resistor behind the 5V reg and set my linear supply's output voltage to 16V with the load attached. So I know that both regs are getting 16V, which is well above their drop-out voltage. Despite all that I still get hiss and whistling. So we can safely rule out the theory of the Murata regs not getting enough voltage. :)

The issue seems to be caused by the way the PSU, Murrata regs and Gator board interact with each other.

Is anyone having the noise issues with the Murata regs and Gator while using the original 15V Caiman supply?

Good info Dave, cheers.
Only ever used my Gator/Caiman with my 16V linear so cant help out there.
I know that theres no whistling with film caps in place (passive mod) regardless of what PSU I used?

[Canetoad]

Hey Bernie...

what I've had from them is an email Titled "Your Receipt Order Number: xxxxx" which breaks down the cost showing both regs at $39.95 each + Tax@ $10.39, totalling $90.29

I'm guessing this is just to acknowledge the order and not the final invoice?
Sure it wont be a problem though :)

*EDIT*
Recent email: "The discount will be applied once we enter the order in and then you will receive an order confirmation from one of our sales administrators. "

Speaking of which,
we should compare dacs at some point - always nice to say howdy. :cool:

Gaz, when I ordered mine the full price was charged on their site but I received an invoice via e-mail as a PDF attachment with the discount applied. If the guy said you'd get a 20% discount you should get it. Get back to him if you don't. Wait a day or so till you get the PDF.

[Gazjam]

cheers Bernie,
:cool:

Got that confirmation PDF from them, 2 Dexa regulators for the princely sum of 43 squid delivered.

Thats a big whack cheaper than UK based sellers have to say...£30 each plus delivery.
Brings out the happy scotsman (i.e. tightwad) in me!

[Canetoad]

Yup! I though it was great value too. Watch your carbon footprint though! ;) :lol:

[maniac]

On the subject of the 12V Murata reg possibly not getting enough head room; I've swapped the Caiman's reservoir cap for a 35V film version, removed the input diode, removed the resistor behind the 5V reg and set my linear supply's output voltage to 16V with the load attached. So I know that both regs are getting 16V, which is well above their drop-out voltage. Despite all that I still get hiss and whistling. So we can safely rule out the theory of the Murata regs not getting enough voltage. :)

The issue seems to be caused by the way the PSU, Murrata regs and Gator board interact with each other.

Is anyone having the noise issues with the Murata regs and Gator while using the original 15V Caiman supply?


Hi Dave, yes, the whistling is there also with Caiman 15V supply. It's also there when cable from Caiman psu to Caiman itself is shortened to about 20cm - i've tried even that :)

[Reid Malenfant]

These regulators that are causing problems... You do realise that the problem is downstream of the regulator? ;)

All or should i say just about every regulator that has negative feedback (which covers any i can think of) shouldn't oscillate unless there is something connected after the regulator that is seriously affecting the feedback loop that stabilises it's output.

SMPS can become unstable if too much external capacitance is connected following the PSU, a cure is to place an inductor after the PSU so the SMPS doesn't see the extra capacitance.

I'm not saying that is what is going on here, but it does sound like the regulator is becoming unstable & causing a low level oscillation at a certain frequency :rolleyes:

[maniac]

SMPS can become unstable if too much external capacitance is connected following the PSU, a cure is to place an inductor after the PSU so the SMPS doesn't see the extra capacitance.

I'm not saying that is what is going on here, but it does sound like the regulator is becoming unstable & causing a low level oscillation at a certain frequency :rolleyes:

Hi Mark,

sounds interesting, but would it apply also when whistling is there with Caiman 15V SMPS but also with linear laboratory PSU? Whistling disappears when I turn down the voltage to 12.9V on linear PSU (lower voltage than 13.0V will put regulator to just pass-thru and not regulate).

In Murata data sheet there is recommended to put some capacitor to Vin+gnd of regulator if there is long path from PSU to regulator. I've tried to shorten the PSU-Caiman power cable but without any success. I've also tried putting caps to Vin+gnd on both muratas - there was change - the whistling tone disappeared, but the sound on all outputs was grainy (like there would be error at DAC output for let's say least significant 4 bits).


By using inductor you mean to put ferrite bead around cable going out from PSU?

Tomas

[Reid Malenfant]

Yes, if the regulator can't regulate at the proper output voltage then it'll have an open feedback loop (it'll be trying to turn on harder to get the correct voltage but it can't as the input is too low) & there won't be any oscillation. The output will be hard on, it won't actually be regulating at all, but acting like a pass transistor as you mentioned.

This just reinforces my thoughts that it is something on the output that is loading the regulator in such a way as to cause it to go unstable ;)

[HighFidelityGuy]

What voltage are you reading at the 12v regulator (pin in) with the DAC powered up?

Regards

Chris

16V :)


Good info Dave, cheers.
Only ever used my Gator/Caiman with my 16V linear so cant help out there.
I know that theres no whistling with film caps in place (passive mod) regardless of what PSU I used?

No probs. I too had no problem with whistling or hissing with the passive mod when everything else was the same. It only started after installing the Gator.


Hi Dave, yes, the whistling is there also with Caiman 15V supply. It's also there when cable from Caiman psu to Caiman itself is shortened to about 20cm - i've tried even that :)

Thanks. So it seems to me that the supply isn't the cause as the symptom is still there with different supply types and voltages. This also tallies with what Mark is saying.



This just reinforces my thoughts that it is something on the output that is loading the regulator in such a way as to cause it to go unstable ;)

Thanks Mark. This takes things back to a suggestion I made earlier that the Elna caps near the regs may have too much ESR or may be too big. That is if they are connected to the reg output and not the input. Can anyone confirm if they are connected to the output?

If so there could be multiple possible cures:

1. Swap the Elna caps to something to a different type that doesn't cause oscillation.
2. Remove the Elna caps if they aren't needed with the Murata regs.
3. Swap the Murata regs to Dexa's as the the Elna caps may not cause them to oscillate.
4. Perhaps it's the tant caps causing the oscillation rather than the Elna lytics? So maybe swap or remove them?

What do you think Mark? :cheers:

[chrism]

Or a solution that removes the two levels of regulation i.e two PSU's one to deliver 5v and the other 12v. That's where I ended up and it works a treat. I don't use a Gator though so not certain if this would eliminate the whine.

Regards

[HighFidelityGuy]

Or a solution that removes the two levels of regulation i.e two PSU's one to deliver 5v and the other 12v. That's where I ended up and it works a treat. I don't use a Gator though so not certain if this would eliminate the whine.

Regards

Yes, that's true. There are a couple of downsides to that though. The cost and complexity will be prohibative to some but also there's the issue of actually needing more voltages than that. From what I understand, a feed is taken directly from the power input (before either reg) to power the headphone opamp. So that would need to be taken into consideration if you wanted to use the Gator or standard Caiman/7520 opamp board for headphone use. :)

[StanleyB]

Somewhere down the line I seem to have misplaced my Murata regulator version of my test Caiman so I can't work on a solution. I suspect that I lent the unit to someone but forgot who it is :doh:. The set I got off someone on AoS is now fitted to the forthcoming TC-7510/Caiman+ replacement so I don't want to butcher that prototype.

Anyone got some pulled Murata regs that I can borrow/steal?

[Canetoad]

Stan, I have a set you can use if it will help everybody out. PM me your address and I'll post them. :)

[Gazjam]

Stan, I have a set you can use if it will help everybody out. PM me your address and I'll post them. :)

Beat me to it :)

[Reid Malenfant]

1. Swap the Elna caps to something to a different type that doesn't cause oscillation.
2. Remove the Elna caps if they aren't needed with the Murata regs.
3. Swap the Murata regs to Dexa's as the the Elna caps may not cause them to oscillate.
4. Perhaps it's the tant caps causing the oscillation rather than the Elna lytics? So maybe swap or remove them?

What do you think Mark? :cheers:
I don't know Dave, i'd be able to probably give some positive comments if i had one on a bench in front of me & could get my oscilloscope on the regulator input & output to see what's going on.

I don't like guessing, sorry ;)

The thing with these regulators is they offer a wider bandwidth, they are a lot faster to respond to current demands than common or garden regulators. They also offer lower noise & more DC accuracy & probably over a wider temperature it's more stable.

This may sound nuts, but a small inductor following the regulator & before the capacitor may well be beneficial in slowing things up a bit to prevent oscillation :scratch: I'm not suggesting you try it, but i think i would just to see what happens. 50nH kind of springs to mind, should be a nice low resistance even in a small package but with enough inductance to give some kind of isolation between the regulator & capacitor...

Could be a country mile out though :eyebrows:

[paul_cz]

Bernie,
also have Dexa-Regs here I want to fit in my Caiman ... Tell me, did you attach heatsink to them? I wonder if heatsinks will fit within the box at all.
Report is welcome ;-) Cheers,
cz

[Canetoad]

No, I haven't fitted heat sinks to them. I don't think they need one in this application (low current). Somebody with more knowledge may be able to give you a more detailed reply.

[Gazjam]

See the photo HERE:
http://theartofsound.net/forum/showpost.php?p=240866&postcount=51

no heatsinks ;)

[paul_cz]

... thanks! cz

[paul_cz]

Hi! Managed to put the Dexas in last night. Whistle when using the Gator is gone. First Impression is good :-) Also managed to attach small heatsinks. The Regs (Especially the 5v one) get quite "warm" - I meassured about 55 deg C. Is this within the normal range? And do you (the other Dexa users) run your Dac with the R1 wire link or did you reinstall the resistor?
Cheers, cz

[paul_cz]

... some images illustrating last night's work. Cherrs, cz
http://tapatalk.com/mu/c30ece70-24a3-0c3b.jpghttp://tapatalk.com/mu/c30ece70-24b5-9afb.jpghttp://tapatalk.com/mu/c30ece70-24c7-9c4a.jpg

[Gazjam]

Fitted the Dexa's myself and very happy to see the back of that annoying background noise :)

Dont know about temps or anything, but MartinT has been running the Dexa's for some time now without any heatsink.
Good question about the R1 wire link, I've removed the resistor in my Dac and the regs seem to work fine?
Would it better with a resistor in there...dunno.

I'd be interested in other Dexa reg users and if found the regs sound changed over time. My experience (using my lug'oles) is that most electronic components DO show change over time from new.

Just wondering about these Dexa's...

[paul_cz]

Hi! I can report that the Caiman and the Dexas are still fine. They get hot but this seems to be a local phenomenon. Even with closed lid the top surface of the Caiman stays cool.
Think the Dexas settled down already. Sound in passive mode (Rubycon Bi-polars from Tirna) is good, very open, stable with sweet tops. Will stay passive for a while ...

[Reid Malenfant]

Good question about the R1 wire link, I've removed the resistor in my Dac and the regs seem to work fine?
Would it better with a resistor in there...dunno.
Absolutely not, keep the wire link ;)

I'm not 100% sure on this but the resistor is probably used to drop some voltage to the standard voltage regulator so it doesn't get too warm?

While it will certainly help in that respect, with any varying current drawn the input voltage to the regulator (with the resistor) will rise & fall according to the current drawn by the circuit. The regulator, or any regulator for that matter will have a far easier time (& produce a vastly more stable output) with the resistor replaced with a link wire.

As you are using a nice dedicated regulated PSU to power the Caiman it seems like a waste of time to bugger up that regulation by fitting the resistor again :lol:

[Gazjam]

sounds good to me Mark, always happy not having to do any more work!

thanks.
Gary.

[HighFidelityGuy]

Ok, you've convinced me to Mark. I'll stick with the wire link and my custom heatsinks. :)

[maniac]

Status report: Muratas replaced with Dexas and viola - no more background hiss. Finally! :) My thanks goes to to aos members.

First impression is that sound is considerably bass lighter than with Muratas , maybe with overall lest punch. Will let it burn in for some time to reconsider. Also i'll possibly try to replace fuse with HiFiTuning T2,5A one I have spare now at the moment.

iMac -> toslink -> Gatorized Caiman with Elna caps mod, Dexas and Gator HD800 bass mod -> HD800

[MartinT]

Bass lighter sound often indicates cleaning up of the signal path. Give them more time to burn in.

[Canetoad]

I have the same mods to my Caiman and the bass reproduction in my system is superb. :)

[Gazjam]

same here.

The Dexa's offer better resolution, soundstage and yes...bass. :)
It'll come back, nae worries.

[Canetoad]

If anybody is interested in fitting Dexas to their Caiman, PartsConnexion has them on special till the end of the month.

http://www.partsconnexion.com/regulator_dexa.html

A bargain at that price! :stalks: :eyebrows:

[maniac]

If anybody is interested in fitting Dexas to their Caiman, PartsConnexion has them on special till the end of the month.

http://www.partsconnexion.com/regulator_dexa.html

A bargain at that price! :stalks: :eyebrows:

Yep, I've ordered them from this site as recommended here and the service was fast and price great :)