Murata regs + Caiman = Problem??

[HighFidelityGuy]

I'm waiting for Gaz to get his installed seen as he'd already ordered some. If they fix the problem for him then I'll order a set ASAP.

[Gazjam]

Hey Dave,

Back from a weeks camping holiday in sunny(not) Scotchland.
Back at home Monday, the Dexa's should be sitting inside my front door.

I'll fit them as soon as i get a new tip for my soldering iron or ASAP.
Whichever's sooner

Fingers crossed, heres hoping the whistles gone...as im out of ideas.

[HighFidelityGuy]

Hey Dave,

Back from a weeks camping holiday in sunny(not) Scotchland.
Back at home Monday, the Dexa's should be sitting inside my front door.

I'll fit them as soon as i get a new tip for my soldering iron or ASAP.
Whichever's sooner

Fingers crossed, heres hoping the whistles gone...as im out of ideas.

Excellent, thanks Gaz! I'll keep my fingers crossed for you.

[Gazjam]

Well, the verdict's in on the Dexa regulators vs. Murata's...

the Murata's were the culprit, the whistle is gone.

Took my Dac over to Tirna Electronics last night to let Jimmy Dripps to let him do the work for me.
(I struggled to remove the Murata's myself and quickly decided best to leave it to the experts )
Got home plugged the Dac in last night - ahhh...thats better.

Speaking with Jimmy about my dac problems, he gave his theory on what might be causing the noise problem with the Murata's.
Not everyone with them has had the same problems myself and others have had.
Why?
Jimmy thinks its a case of bad luck having a mismatched pair of regulators which operate at a frequency too close to one another.
He says (and I misquote) that this could cause oscillation in the regulators leading to an an audible "beat" which manifests as background noise when playing the Dac.
I mentioned that I would be putting up my Murata's on AOS as an upgrade for someone and he was generous enough to swap over one of my regulators for a different one from his spares.
A nice gesture and a genuinely nice bloke.

Have to say as well, over and above the whistling being gone my Dac is sounding better than ever.
Read up on these Dexa regs and they are offered as upgrades to existing kit by several 3rd party modding websites - even for kit like the Rega Saturn cd player and Wadia transports.
An upgrade to the Saturn..Wadia? Must be good then!
Forum posts on DIY sites too talk about the Dexa's being a great upgrade to existing kit, so think I've made the right choice fitting them in my Dac.

One question though...?
I've always found new components tend to improve over time, is this the case with these Dexa regulators too?
Good improvement in soundstage focus and detail right out the box, but I'd say there was a shade less "impact" and front to back stuff from what I remember before?
Overall a good bit better than before, but just something I noticed.
Should it potentially improve over time?

So really...I've modded my Dac now about as far as I can take it, nothing left to do - extremely happy to have my (improved) sounds back.
With all the SB Touch software mods and my improved Dac, things are sounding good.

[Canetoad]

One question though...?
I've always found new components tend to improve over time, is this the case with these Dexa regulators too?
Good improvement in soundstage focus and detail right out the box, but I'd say there was a shade less "impact" and front to back stuff from what I remember before?
Overall a good bit better than before, but just something I noticed.
Should it potentially improve over time?

I was thinking the same thing the other day when I was listening to it a bit louder than usual. I was thinking it might improve after I fit a new linear supply set to just under 16v. Currently I'm only running on just over 15v and the internal diode is cutting that back by about .6/7v. Once the Dexas are being fed a full 15v I'll see if the sound improves.

They still sound very good though.

[Gazjam]

I was thinking the same thing the other day when I was listening to it a bit louder than usual. I was thinking it might improve after I fit a new linear supply set to just under 16v. Currently I'm only running on just over 15v and the internal diode is cutting that back by about .6/7v. Once the Dexas are being fed a full 15v I'll see if the sound improves.

They still sound very good though.

How long you had the Dexa's in Bernie?
I've a linear PSU set to about 15.6v, good improvement over Maplins linear CB radio supply.

Internal diode?
Is this the resistor just next to the 5v regulator?
I removed this and replaced it with a wire link, would this mean I would have no voltage drop then?

ta.

[Canetoad]

No I gather it's a protection diode near the large cap. I'm using the CB Maplins supply and I'm getting 15.1v from it. I have the bits for a new linear supply using a Superteddyreg as per MartinT's PSU but haven't put it all together yet.

[Gazjam]

ah..I see.
Another potential thing to do with my Dac..

Anyone have experience of removing this diode?
Is it advisable with my linear psu running about 15.6v..I know Stan advises not to go over 16V but I'm just wondering about the effect of removing the diode with the combination of the Dexa's and a 15.6V linear supply.
the Dexa regs have some voltage drop but not a lot.

Is there a pic anywhere or some info on this?
More importantly...is it worth even bothering about

Cheers.

[StanleyB]

Don't remove that diode. It's there for reverse voltage protection. My DACs use a dual power supply voltage regulation design, which consists of an external and internal regulation circuit. The external circuit supplies the raw voltage, which is stored in those big caps inside the DAC's case. The diode prevents the internal supply feeding back into the external supply, and perhaps knocking it out.

[Gazjam]

thank you Stan.

I'll leave it well alone then.