If the OPC271 has a fixed series resistor, how can they claim an adjustment range of -99dB to -0.3dB? Shouldn't the fixed series resistor limit that range? |
From what has been told to me OPC271 (one of the first Lightspeed copies) is like my original Mk 1 Lightspeed Attenuator but with more glitz, which is a series resistor and shunt ldr, while it was still sounding very good and better than all other volume control devices on the market, is not as good as the MKII Lightspeed Attenuator which is series LDR and shunt LDR, which has a lower low volume and more stable input and output impedances, and the main difference it sounds far better, especially in the bass and dynamically.
This is why all the MK1 Lightspeed Attenuators were recalled and converted to MKII status and were well praised by their customers.
I wish I could have continued to make just the MKI as it is far easier to manufacture as the MKII is exponentially harder and expensive to do.
Cheers George |
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Anyone heard the P&S Technologies OPC271 yet? Another Lightspeed clone or something different? It comes as a kit that can be used as a passive or fitted into an active preamp as a volume control. The opto part is a sealed black box that I assume contains matched LDRs plus maybe some other linearizing bits - the performance graphs they show look pretty good. In addition, it comes with an LED display, built in switching for 4 inputs plus HT bypass, remote control and mute. I've written them for some tech specs like input impedance, but haven't heard back yet.
Any thoughts/experience?
http://www.pns-tech.com/products.php |
Wow that's a long one. Who wants to have a possibility to go to the last page from one click instead of paging it through?
Oooh-Gon, please find the power from Allmighty to properly design your web page! that's what '>>' is for |
Wow that's a long one. Who wants to have a possibility to go to the last page from one click instead of paging it through?
Oooh-Gon, please find the power from Allmighty to properly design your web page! |
My brother thinks $500 is outrageous for a complete system. |
Even if you gave it away for free, you'll find someone to complain that it wasn't shipped overnight express.
To be honest though, two years ago, prior to being bit by the audio bug, I also would have said that $500 is 'very expensive'. I know better now. |
From my original posting: "Is it the best ever? I suspect for some it may be, and to say that for a $450 product makes it stupidgood."
"Stupidgood" -- (a phrase not invented by John Gordon Holt or Harry Pearson, but Bobby P. of Merlin Music Systems to describe products that punch way beyond their price point. |
Well even at it's price point I guess not everyone can afford to own the best preamp ever:) |
Devilboy: George, are you joking? Some actually complain about the cost of the current unit? Devilboy
I am serious, here is one reply email from yesterday, and I'm ashamed to say he was from Australia as well.
" Hi George, Thanks for your reply. It's very expensive. I've to save money for this. J"
Cheers George |
220v/240v wall warts are supplied to most countries except the U.S. which is unfortunately 110v. (Just like you guys also drive on the wrong side of the road compared to everyone else).
I refund $15 to those customers and give them a few links to get their own in the U.S. on line.
In Australia it is a safety issue to sell or supply or import 110v wall warts, on suppliers sell them, as you can imagine if one were to be given 240v it would become a molten mass very quickly.
Cheers George |
Goldpoint does a very good job of providing a classy, no-nonsense case for their array of passive preamps. |
George, the cheaper the product the greater the customer service demands. Don't know the name of that law, but it seems to apply across industries. It would be good for you to be able to include the wall-wart with the shipment, though I guess that can get crazy, but I assume the US would be a pretty big market. $1000-#1500 with multiple inputs and a more substantial, fancier chassis should have a strong following amongst the passive set. Congrats on the ongoing Stereophile recognition. |
George, are you joking? Some actually complain about the cost of the current unit? To those that do, I say go out and build a better one at a lower cost. Until you can, buy George's and feel content knowing you have a world class preamp in your system. |
Maybe one day in the future, fancier glitzier chassis, remote control volume, multiple inputs (switched via wetted relays). It will more than treble the price but still sound the same, no better than the original sounds now. And some complain about the $500 shipped worldwide cost of the current unit, go figure what they'll say when it's $1500+ for the fancier one.
Cheers George |
Congrats George! I love my Lightspeed. Any plans to broaden your product line? |
Talk about pride of ownership;). I will give both my LSA's a hug today. |
All you proud Lightspeed Attenuator owners, look out for the upcoming Stereophile issue (I think April issue which comes out in March) with Recommended Components listing, as they just emailed me for any changes (pricing, design etc) to be included in the write up on it.
This will be the 5th time your Lightspeed Attenuator has made it into Recommended Components since 2009 when Sam Telling first bought his from me. I have a feeling it may set some sort of record for Recommended Component longevity.
Cheers George |
When I say source,I mean the recording, not the live event -there simply is no direct connection to it, but the recording is the reference for purposes of the argument here - true to the recording is proabably better language than saying true the source (live event) - that simply is out of our control and always lost in the very processing of recording, no matter how good the recording and playback equipment. I feel like in a Platonic cave all of sudden.... |
You find can many synonyms for the golden rule of audio used by manufacturers and end users alike. It makes for good ad copy. The problem is how you define "source". If by source you mean the recording, then unfortunately 9/10, the harm has already been done. One of the primary "sound sculpting" tools used by recording engineers seems to be compression. The rectification of that and other sins committed in the recording studio makes this hobby a lot more arduous than it should be.
For the sake of clarification, I am referring primarily to digital source material as I am a child of digital revolution. |
In the February issue of TAS, Neil Gader interviews John McDonald of Audience, and he said something that somehow seems related to this thread:
"At Audience,the Golden Rule is 'first, do no harm,' defining harm as any deviation to the original recording. So high-end to me and to the Audience team is about staying true to the music. Sound-sculpting should be left to the recording artists and engineers"
He could have very well had said, "true to the source" - which I suppose is one reason that those that do like the LSA, like it - true to the source is the raison-d'etre [?] of the hair shirt minimalist approach to do no harm. |
It is linear. I, we?, sometimes hear what I expect to hear, at least in the short term. |
Given George's good answer about noise level, and his answer implying that the "line regulation" performance of the internal 5V regulator is good enough to reduce expectable variations in the 12V input to the point that they would not result in a perceptible volume change (which is certainly do-able in a quality design), I'm out of ideas as to what could account for sonic differences between battery and wall wart power (assuming that the wall wart being used is a linear supply, not a switching supply).
Best regards,
-- Al |
So taking any power differences to the LED's out of the equation all we have left is noise difference of battery v mains. But if anyone can hear the difference between 6uV and 4uV they must be superman. I have measured this my Tektronix scope which has very good low resolution.
When the shorted input Lightspeed was powered by the battery I measured a noise floor of close to 4uV (that's microvolts not millivolts) When it was powered by the mains it was then 6uV. These are exceptional figures as most things in audio are measured in mV (millivolts) which is 1000 x higher than microvolts. And so it should be this quiet as it is passive and has no noise of it's own.
But if this is perceived difference some hear (as I also hear) between battery v mains comes down to those miniscule noise differences then the book has to be re-written.
Cheers George |
Sorry guys the internal regulator in the Lightspeed Attenuator is 5v and will be the same regulator regarless of using battery or mains, so ther is no difference in voltage that the LED's are seeing not even a miniscule of a volt.
Cheers George |
Anthony, no, I was assuming in my last post that both supplies are nominally 12VDC. However, neither is likely to be exactly 12VDC, and the two are not likely to be exactly the same. Also, the output voltage of the battery will change slightly as it discharges.
While the significance of those differences will be greatly reduced by the internal voltage regulator, as I said no regulator is perfect. So it seems conceivable to me that if the power source is changed but the volume control setting is not changed, there could be a tiny change in volume that would be subjectively perceived as a sonic difference.
Best regards,
-- Al |
Al, if the voltage output of the battery and wall wart power supplies are both 12VDC does that change anything in your last post? |
Al, that really makes sense. And it seems to explain Clio9s experience, something different but hard to put your finger on it. |
Perhaps the reason some of you are reporting sonic differences between using battery power and the wall wart is simply that volume levels haven't been precisely equalized for the comparison?
I realize that the LSA has an internal regulator, but no regulator is perfect, and so perhaps voltage differences between the outputs of the battery and the wall wart result in slight (fraction of a db) changes in attenuation, that need to be compensated for with the volume control.
To totally rule out the possibility that the sonic differences are attributable to volume changes, I believe that the levels should ideally be equalized to within around 0.1 db, which is probably impossible to do without instruments.
Best regards,
-- Al |
If you know LED lights, you would know they are an extremly stable (even thermally) form of light being powered by battery or regualted mains. This is maybe why battery cannot be picked from regulated mains in an A/B comparisions, like I have conducted many times with fellow audiophiles, a few said they can detect something but cannot put their finger on what it is.
Cheers George |
Given George's explanation, it makes little sense... |
Given George's comment, it would seem the burden of proof is on explaining a difference, not the other way around. I find Clio9's comment interesting, as he does hear a difference, but even there hard to put your finger on it, also hard to measure the influence of expectation on something so subtle. However it may be, going to battery supply just doesn't seem like a path with pursuing, at least not to me. |
I have the battery supply as well. It changes the sound, slower, more polite IMHO. I will listen to it again. |
Because all the supply has to do be it battery or mains, is to hold the LED Light (light emitting diode)steady at a predetermined (by you) luminosity level between 1 and 20mA, this LED in turn shines on the LDR (light dependant resistor)which changes the level of resistance needed to change the volume of the source to the poweramp. As you can now see the power supply has no electrical contact with the LDR or signal. And the led is gas (no filament) so it is impervious to vibrations or shocks.
Cheers George |
One less thing in the world to worry about:) |
That is interesting George. Why do you think the LSA is immune to a battery supply? |
I wouldn't say the battery option improves the sound, but there is something different about the sound when using the battery power supply. I just can't put my finger on it. I go back and forth between the two. |
I would also like to hear other opinions about this from owners.
This is what I found, I have Lithium Ion batteries I use, and no one, even "golden ears" who visit can reliably detect the difference between them and the standard mains supply that comes with the production Lightspeed Attenuator, and this is on a very high rez system.
Even Sam Tellig "golden ears from Stereophile" said the same, as he bought the Lithium Ion batteries as well for his Lightspeed thinking they had to be better (pure dc and all) than the regulated mains but no he said if there is a difference it's miniscule and not detectable.
Cheers George |
I just saw the Warspeed thread on AC and was mildly curious. They could not provide any details on "why" it was better, and it simply seemed like a me-too product. The name even tells you as much. From the listening tests mentioned earlier in this thread, the battery seems to have no sonic consequences.
IMO, George deserves all the credit for this development. It is his intellectual perseverance that has made it possible, and any "new" developments are to be viewed with a jaundiced eye.
Happy listening.... |
Does the LS improve with the battery option? Curious what you folks have found? Not sure why it would, but thought I would ask. |
Agear, seems like your have you answer. The "latest" is syrup thrown on the original and the greatest. But if you still have issues, buy both and decide for yourself; the LSA is still the gold standard, even though it might not be the "latest" -- hard to improve upon perfection. If you personally find something better, do let us know, but you are up against a tough audience of folks who enjoy the LSA. Have you actually used it? Doesn't seem like it. |
Next generation LSA or another opportunist copycat? Neither. The designs are more different than the same. Not even an evolution IMO. All the research I've done says users who've had both prefer the Warspeed and that this one is pretty much the best of the bunch. Curious to hear why as well, though. Everyone is entitled to an opinion. I have both units and can say the LSA is clearly the purist and smoothest sounding of the two. My reason for buying the Warpspeed is that the builder makes a balanced version which I wanted to try with my Otari reel to reel. It does the job, but it's not the final answer for me in this application. |
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Dual L&R volume controls are the only option I provide for the Lightspeed Attenuator.
It is the only one that does not effect the sound quality, though as you can imagine it is slightly more difficult to use, but a boon to those who have unsymetrical systems or room acoustics.
Cheers George |
As you noted earlier in my question about an improved version, it seems that after 30 years of tinkering, the LSA is well sorted out, and at some point there is little to improve, without as you say paying a sonic cost in the service of some other goal. To me, the only issues are stability over time, and balance control - which unfortunately requires dual volume controls for best sonic results. |
It's all good to add fancy ways of not having to quad match the LDR's but the end result is there's more junk in the signal path and it results in differing sound qualities (not levels) at different listening levels for each channel. This below is what I posted at DIY about the same subject.
"You need to look and measure that the I/O impedances of both channels at differing levels remain the same to each other, if not and they have different values of Z in and out (i/o), this will effect the sound quality of each channel hence may/will effect the stereo imaging. It will simulate the same effect as having large different lengths of interconnects for each L and R channel.
That is why quad matched sets have a consistency between channels, they remain equal for both at all levels of listening, unlike some of the pseudo Lightspeed Attenuators that are comming thick and fast. There is no free lunch."
Cheers George |
Yes, it would be good to hear from someone who has actually owned both, or auditioned both at length? Anyone on Audiogon? You?
As far as I know, the LDRs themselves are identical, but Alan appears to have tried to address some ergonomic issues, a more complicated device it seems. Sometimes a tradeoff, especially with an approach principled on simplicity and minimum of parts, contacts, etc. Would not mind trying a WS to see, but not many available, and I certainly could never make one for myself from a kit. |
Recent quote from the AC thread:
"All the research I've done says users who've had both prefer the Warspeed and that this one is pretty much the best of the bunch. Curious to hear why as well, though."
and
"I could be wrong, but from what i've read it sounds like the Warpspeed LDR is the newest type of LDR to come to market. The Lightspeed is an older design. " |
I think George addressed this 09-29-11 - after I asked a few questions regarding the Warpspeed. |
