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In Reply to: RE: Noise is bad posted by Mercman on September 12, 2014 at 17:24:16
Finally you have taken this on board. What's the PS? Hope they are better than Teradak or those that use the 1086 family of chips.
Follow Ups:
They are HDPlex. My friend CG recommended them to me. I have one driving each of the GRAID Thunderbolt drives.
Edits: 09/13/14
Not a very good regulator but will probably do. The rest depends on mains isolation I guess.
Teradak may be cheaper but I don't know about pricing in US.
Do you really need 2 and not just one with higher power that is well isolated from the mains?
I forgot to answer your other question of why 2 power supplies. The HDPlex can power a 12v and 19v simultaneously. I needed 2 12 v supplies. If you want to modify one for me, come over today.
The hd-plex supplies use an R-core transformer, which have far more isolation from the AC mains junk than pretty much any other transformer design.
The regulator itself isn't anything special, but is quite reliable. But, the regulator output is heavily filtered by an array of caps in a "pi" type LC filter. No regulator is worth a crap beyond maybe 100 KHz - and all "3 terminal" varieties far lower than that - so passive means are the only way to give good filtration and low output impedance. In this design, it works both ways by filtering the junk getting back into AC mains from the computer or hard drive.
Getting rid of noise is really the main thing here, however you do it. The other reasons for heroic regulators aren't so applicable in this sort of application.
The hd-plex isn't perfect by any means. There's really no common mode noise rejection beyond what's inherent to the transformer, as an example. That can be externally added easily enough, if desired or needed.
My friend CG provided this explanation to me.
The HDPlex are plugged into my AC conditioner.
R-Core true or tale? Who knows?
You can always use an isolation transformer (proper one).
There's absolutely nothing wrong with the LT1083 regulator for the application it is being used in your setup.
Since Fred is so quick and frequent in his dismissal of components, designs, and products by others, I wonder what he considers to be the best regulator for your application.
Thanks Abe. It's just Fred's way of doing things.
I am jot going to respond to anyone who know little except buy Apple products. I am not referring to you. Lt 108xs are very old hat when it comes to regulation but it is cheap and easy.
Lt 108xs are very old hat when it comes to regulation but [are] cheap and easy.
The LT108x regulators are indeed cheap and easy but, as John Swenson has pointed out elsewhere, if you use well designed L-C filtering up front to take care of higher frequency noise, the likes of the LT108x are perfectly adequate.
This seems to be the case here: ". . . passive means are the only way to give good filtration and low output impedance." Designing such is not fiendish but it does need competent component selection and doesn't come cheap.
Having DIY'd several C-L-C PSUs to John's design, I can confirm they work very well indeed. I've even tried fancy regulators in place of the specified LT1084 but found they made little, if any, difference. I suspect these are good products.
Are they good value? Lucy is looking a little coy.
I would have not said anything to someone who doesn't pay thousands for a cable and other gadgets and yet not seek the best for a power supply.
A superregulator powered by an ultra isolation transformer will have much better bandwidth and isolation.
This business of R Core can be an old wife's tale. I know for a fact that some China sourced R cores are iffy to say the least. I'd much rather go for a high quality anything.
I almost forgot to include this:
"A "superregulator" only gives good noise rejection through the bandwidth of the control opamp. That isn't really very high in frequency in the overall scheme of things relative to computers. Any knowledgeable engineer knows this. Or, ask Walt Jung. You need passive filtering to complement whatever regulator you use. That's not an indictment of these regulators - what they do, they do very well for their intended purpose. BTW, their intended purpose is only partly to give noise rejection - the designers of these regulators usually are just as concerned with flat, low terminal impedance across the audio band. Maybe more."
This information came second hand to me. Lucy gave it to me after discussing the issue with a Doberman who lives on our street.
I suggest that do some research and compare them with your LT1063 spec sheet in terms of bandwidth, output noise, regulation, output impedance etc.
Mine comfortably does 5 uV noise wideband to 1 MHz +, beyond which I did not have the instrument to measure properly.
Second hand info needs to be scrutinised on the basis of context and accuracy.
My 2A 12V units cost me no more than $50 to make and I can churn them off repeatably.
I need a minimum of 4A for the GRAID drives.
But Steve,
You can always use an isolation transformer (proper one). ;-)
I wonder what brand and model would constitute a "proper one" for YOUR APPLICATION. It's easy to be vague.
A superregulator powered by an ultra isolation transformer will have much better bandwidth and isolation.
But it won't power your disk drives because the designs I've seen won't supply the necessary current. Besides, these 'superregulators' are designed for audio circuits, not for supplying the current demands of HDD motors.
Your HDPlex power supply is very well suited for YOUR APPLICATION, which some folks here can't seem to grasp.
Abe,
Fred's design puts out 2A. I need 4A. You obviously know what you are talking about.
Which specific 'superregulator' design (by whom) and what version is Fred suggesting? There are several out there that claim to be 'superregulators'.
Is there an online schematic of the specific design he is talking about?
not a problem, just uprate the power transistor.
But this was not my point. My point was that the LT 108x based PSs are at best slow and mediocre, with limited bandwidth, and that 2nd hand opinion needs to be processed and not just repeated in a discussion of any value.
I am sure that you must be aware of much better PSs if you visit Computeraudiophile.com
I have no doubt I could purchase far more expensive power supplies. Would there be beneficial sonic results? I really don't know. But I do have something coming that might shed some light on this.I do know that the HDPlex sounds better than the SMPS. But then again Fred, I NEVER stated that this was a state-of-the art solution.
Edits: 09/15/14
you have just said was what I set out to say. Really there was no need for this prolonged and defensive exchange.
.
Lucy feels they work well and appear to be very well built. Quite frankly, I was surprised at the quality of the case/heat sinks given the price. Some of these expensive DACs I review don't look and feel as nice.
It's this business of closing your mind because you own something and was told that it was 'good' again.
I would have thought that your recent 'conversion' on setting up your computer would have opened you up for input other than what you have bought.
"My friend CG provided this explanation to me."
LOL. I read your post in wonder as rarely do I see viable (ie ones I agree with) "technical explainations" on AA. While I very much enjoy your reviews, especially the ones about, er, 'unusual' products, I was shocked that you had managed to turn so insightfully technical on me. Think of how amazed you'd be if I suddenly seemed to have developed an insider's view of anomalies of the big toe...
I think it's great to have resources to draw on to help flesh-out reviews and put them in context. Adding upfront information and viewpoints help us better comprehend the issues.
Thanks, Rick
Just think how great it would be to have CG actually doing the reviews.
Thanks Rick
"Just think how great it would be to have CG actually doing the reviews."
Maybe, but I like yours. Experiencing is a different process than analyzing and I at least can't do both well at the same time. I like going into things with a 'blank mind' (my sister says that I'm a natural...). Trying to sort out what's happening tends to interfere with properly perceiving the gestault in the first place. Once the perceived performance characteristics are firmly in mind then comes the time to start thinking causation...
Regards, Rick
These drives are going to be discussed in my next review of the Shunyata Hydra DSP-6. All I need is the Hydra :)
Hey, why have any drives at all to power? You can use the Thunderbolt connection to copy to RAM and then play out of RAM. You can power down the Thunderbolt drives, unplug their power supplies, etc... Not only does this remove a source of sonic pollution, it makes reviewing much easier, since there are fewer components that need to be considered when it comes to component interactions, etc...
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
great way to play music???
Not the most convenient way, but certainly one with a small number of components in the playback chain, powering the playback chain, or otherwise degrading the sound quality.
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
Thanks for the suggestion Tony.
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