10-11-11: Devilboy
Thanks, George. The input impedance of my amp is 470K. I can't imagine that being an issue with the Rothwell's.Devilboy
No that is not a problem, what is the problem if you go passive or tube preamp, is that while the 470k input of your amp is fine for these preamps, when you plug in the Rothwells then this changes that 470k for something much smaller. What I don't know as I have never measured the shunt to ground resistor of the Rothwell, It maybe say "10k?" then this is seen by the passive or tube preamp not the 470k, and then it will not be a good impedance match for them.
As Clio09 found out when he used them, it wasn't the Rothwells them selves that he didn't like it would have been the input impedance change of the poweramp he heard that then was not a good match with whatever pre he was using at the time.
There is no free lunch, you have to do your homework, regarding impedance matching. Like I said before it goes on right through the whole system from source through to speakers, up to about 6 to 10 times, you can't do anything within the components themselves unless you are a good tech, hopefully the designers of individual components have done the right matching inside their units, but you can look at the output and inputs of each component to make sure you have a good match and give everything a fighting chance to sound it's best.
Cheers George |
We did a comprehensive listen test with the Lightspeed Attenuator with 20 odd "golden ears" from our audio society.
The amp we had was specially modded on the input that we could changed the input impedance in steps on the run while listening from 200k down to 10k. The source was 10ohm output impedance.
What we found that everyone agreed on was there was no change from 200k down to 47k only when we got down to 33k it was felt by some that a slight compression was noticed, then when we went down to 20k all noticed slight compression.
This is why I state in the Lightspeed Attenuator info/instruction sheet the poweramp should be 47k or more, to get 100% transparency and dynamic transfer, 33k is still ok and safe to use, but you may notice a slight compression of the dynamics. |
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 |
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 |
I can now see why you preferred the tube preamp that has gain Grannyring. As your Aesthetix Atlas power amp has well below the standard input sensitivity at 3.1v. The input impedance was fine at 470k or higher (as you measured) but most amps on the market need 2v or less input sensitivity to drive them, your amp needs 3.1v most sources only have 2v (Red Book standard) so this amp is not suited to preamps that are unity gain active or passive.
If you could of raised the gain of the Atlas by a higher "gain" input tube or lowering the feedback, way so it became 2v or less input sensitivity then I would dare say that you may not have sold your Lightspeed Attenuator.
Cheers George |
I believe I stand to be corrected, I see that it's the Atlas "monoblocks" that are 3.1v sensitivity, these are not suited for unity gain active or passives preamps, they will work but fine with maybe a source headroom disadvantage.
However I now been told the stereo version of the Atlas is better at 2.3v sensitivity, much better for unity gain actives or passives, this is why you like it, still not as good as 2v or less sensitivity amps, which most are.
Cheers George |
Or you could try a pair of the Rothwell inline rca attenuators, they come in -10db & -20db.
http://www.rothwellaudioproducts.co.uk/html/attenuators.html
http://www.decibelhifi.com.au/category42_1.htm
But I would prefer to go to the trouble of reducing the gain of the poweramp or source.
Cheers George |
We did experiments with different input impedance to a specially modded poweramp that we could change on the fly while listening. This was with about 30 "golden ears" at our club through a very revealing system, we went from 300kohm input impedance down in steps while the music was playing all the way to 33kohms before just one thought he noticed a slight compression, and he was not sure.
As for cable capacitance anything below 100pf per foot is fine, as with 100pf per foot that would be approx 300pf for 1mt this would equate to a -3db HF roll off at 76khz.
Cheers George |
I prefer a battery, but I cannot say why, if I did a blind test I could not say which was which.
Sam Tellig of Stereophile says the same, he prefers the battery when he know which is on, but cannot say why either.
Go to ebay and type in "12v Lithium Ion rechargable" make sure with the seller that the lead that comes with it is a 2.1mm plug and center is positive. If center is negative you will cause damage to the Lightspeed.
These 6800mAh Lithium batteries are good for 2 weeks before needing a recharge, they are already overkill so no need to get bigger.
Cheers George |
Hi Chuck,(Lacee) it is good to hear it got there safe and sound, and your initial listening session is positive. Please give us a more in depth review after a couple of more days, I think you will find even more will be discovered.
As for your findings of the sound difference of the two separate wall warts, I have an idea which may be the answer. One of them could be a Switchmode (SMP) and the other a Linear. Depending on quality of the Switchmode they can sound "zippy". As they can inject HF rubbish into the circuit by air or through the wiring.
They are hard to tell apart visually but usually for similar power (mA) eg: between 300mA to say 500mA ratings, a Switchmode wall wart will be much lighter than the a Linear wall wart.
Let us know how you go.
Cheers George |
Ditto with what Clio09 said Devilboy, you have a great system match for the lightspeed with those parameters.
I also have clients that have poweramps with 20kohms input and say "they couldn't imagine it getting any better than this".
Cheers George |
If your Ayon has a digital domain volume control and you are able to use it within it's top 1/3 of it's full output range, so you are not "bit stripping", then only this will be even better than having a Lightspeed.
Cheers George |
Audiolabyrinth hi.
All the gain 2.5v/5v switch is doing is changing the feedback resistor on the output buffer to another value to give 5v instead of 2.5 on the same output buffer.
As far as being concerned that you have 5v out feeding into 3.5v in, this is quite acceptable, as if you had an active preamp in the mix you would have far more than that, as some are capable of giving out up to 20v or more out.
So as you can see it is not out of the ordinary to have more out than what's can go in, just means you have a bit of headroom, just be judicious with the volume control.
And like I said if when on the 5v setting you are below 2/3 of full volume then "Bit Stripping" can become an issue. Then you can get a Lightspeed have the 5v full up and the Lightspeed will be at or around mid 12o'clock position for normal listening with more available if needed. Or you can leave the Lightspeed at say 2o'clock and be able to use the remote volume on the Ayon to raise and lower the volume within the top 1/3 of full up, this way you will not be "Bit Stripping"
Cheers George |
As for use with battery, I recommend the use of 12vdc Lithium Li_ion rechargeables, these will give a couple of week use before needing a recharge. One important question you have to ask the seller is that the plug is 2.1mm and very important that the centre of the plug is + positive.
http://www.ebay.com/sch/i.html?_odkw=12v+li-ion+rechargeable&_osacat=0&_from=R40&_trksid=p2045573.m570.l1311.R1.TR2.TRC0.A0&_nkw=12v+li-ion+rechargeable+battery+pack&_sacat=0
Cheers George |
Those who have a Lightspeed Attenuator and wishing to try a different power supply instead of going battery.
I've been shown this quite reasonable priced one which is a nice linear regulated product. And comes with the correct lead, plug and polarity (2.1mm center positive).
This is 9vdc @ 1A which fine for the Lightspeed Attenuator as it converts it down again with it's internal 5vdc regulator.
http://www.ab-system.hk/index.php?route=product/product&path=73&product_id=64
Cheers George |
No I have not tried it, but I have compared pure battery power to the standard supplied power supply, and the difference is subtle, you can't put your finger on it, that subtle that you forget which is on.
I posted this power supply as it looks impressive for the cost, and looks to be very very well made both in circuit and appearance for the money. And you get a bonus with it, a well regulated linear USB 5v supply.
But no I have not tried it, but you know what audiophiles are like, especially with power supplies and plug in tweaks that don't cost the earth.
http://www.ab-system.hk/index.php?route=product/product&path=73&product_id=64
Cheers George |
OK for US and Canadian owners of the Lightspeed Attenuator, I just did a search for definate linear wall warts that are all suitable.
First three are regulated, last two are unregulated, it does not really matter, so long as they are linear 9-12v with a 2.1mm plug that is center positive which they all are.
Or you can get the Teradac http://www.ab-system.hk/index.php?route=product/product&path=73&product_id=64 Cheers George
110-115v linear wall warts from Jameco, payment by COD, Paypal or Credit Card
All are suitable.
http://www.jameco.com/webapp/wcs/stores/servlet/Product_10001_null_220898_-1
http://www.jameco.com/webapp/wcs/stores/servlet/Product_10001_null_1953639_-1
http://www.jameco.com/webapp/wcs/stores/servlet/Product_10001_null_162996_-1
http://www.jameco.com/webapp/wcs/stores/servlet/Product_10001_null_2192712_-1
http://www.jameco.com/webapp/wcs/stores/servlet/Product_10001_null_2197484_-1
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Hi, Audiolabyrinth, tell him to come over here and read this.
I had a quick read of that thread, and there are those that like to be on the preamp merry-go-round, spending lots of money and are addicted to it.
They say that their preamps aren't coloured. But keep changing them for "different sounding ones" (odd I thought they were uncoloured).
I have yet to hear them use the statements like "straight wire with gain" or "true to the sound of the source" as these statements are describing a preamp the is truly transparent, dynamic, uncoloured and invisable to the sound of the source.
Cheers George |
Dhcod hi, I had a bit of a search and yes your Purest Audio cables are very good low capacitance ones. They are fine to use with many tube and most passive preamps, and will not cause early (into the audio band) high frequency roll off. I would keep these to a max length of 1.5mts from pre to poweramp. I looked at most of the ones they give specs on, and they give the 1mt length pF (pico-farad) capacitance and all that I saw are under the 100pf per ft measurement I gave earlier. This is good to know that some cable manufacturers are responsible and doing this specification for their customers, who know how to use it, for their systems compatibility with them. http://www.puristaudiodesign.com/products/interconnects.phpCheers George |
04-28-14: Luxsound
Has any one used his LSA with active monitors?
mine do have an input impedance of 10KOhms, which is not the recommended 47Kohms.
Output impedance of the source is extremly low though.
any thoughts? It all comes down to what the source can drive, because it will need to drive the combined load of the Lightspeed and the active speakers If it (the source) has a very low output impedance say below 50ohms there should be no problems. But say it (the source) has a tube output stage then some of these can be very high in output impedance ( some up to 5Kohms), they could have trouble in this particular case. Cheers George |
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05-19-14: Erwann
Hi George,
I just had a quick glance at the Audiogon thread to figure out whether I can find a better power supply than my decommissioned Prius auxiliary battery, and I fail to understand how a Teradak, with or without a fancy cord, could offer an improvement other than convenience. I guess the answer is that you haven't felt an overwhelming urge to try it yourself. Not being an exhibitionist, I personally think that my best audio component is my brain with ear input, which in addition to being portable and self-powered, doubles as the biggest sex organ, but I'm still burning it in at sixty-six, and it keeps improving. I strongly believe that battery is the "technically" the best form of dc supply for the Lightspeed Attenuator. But sometimes I forget which is on mine, the battery or the linear wall wart, they're that close to each other. Sam Tellig of Stereophile uses both battery or wall wart on his Lightspeed, and so does his guitar teaching son on his Lightspeed. And both can hear a slight difference but can't say what that difference is. As for the Teradac power supply, if you technically want a very good mains powered supply for the Lightspeed that to me is total overkill, this is the one to get. And it's only $44. Some here that have used it, swear it's the ultimate mains powered supply. I have never used one so I cannot comment on it, but on paper it's miles ahead of a linear wall wart, but to me technically battery is even better again. Cheers George |
The Lightspeed can never go to complete zero volume (there is always a whisper at min) and in rare very high gain systems such as Fins the volume will be down around 9 or 8 o'clock low for normal listening level, and this will give the impression of more "gain" than a passive that can go to complete zero level.
As "Fin" (Andrew) contacted me about this last week, he gave his system parameters to me. And as you can see below he has a s**t load of gain, with effecient speakers.
They are:
source >2.5v out
power amp <1v in.
As you can see he needs only 1 volt in to for his amp to give it's 100w full power.
And he has more than 2.5v from the source.
And because of this the Lightspeed is down low for normal listening.
Cheers George
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So is the Beryllium(Be) used in Focals/JM Labs and other speaker manufacturers that use Focals top tweeters. So is Yamaha NS1000, NS1000X and NS2000, tweeters and midrange units. So is NOS and OS tubes that have Nickle(Ni) inside them. And so is the lead(Pb) based solder hiend manufactures still perfer to use. I can go on and on, at least the Silonex LED/LDR package that the Lightspeed Attenuator uses, are hermetically sealed within a tough hard acid resistant plastic case, I don't think anyone is about to open up a Lightspeed Attenuator put one in their mouth and crunch down on it like a boiled lolly. It's not "Cadmium Gas" it's Cadmium Suplhide (CDs) solid. http://en.wikipedia.org/wiki/Photoresistor http://en.wikipedia.org/wiki/Cadmium_sulfideCheers George |
Maybe then for those people they should be using 100 band parametric equalizers, but then that's just adding even more electronics with their associated colourations and distortions.
And then instead of hearing the music in it's "naked glory" we are hearing sterilized distortion infused approximation. |
Back to responding to Lightspeed owners posts, after being sidetracked about my own system which I did in laymans terms, which is far to complicated to explain in full here, and not the right thread either. 09-12-14: Gracerev
I just got the Lightspeed Attenuator. It came quite simply but securely packaged. The design is pleasant and solidly built. Was excited as I've read so much about it in the forums. Wanted to see if all the hype was for real.
After running in for about 4 days, I can honestly say it has lived up to the hype. Through my Esoteric transport/Bricasti DAC, which itself was already very transparent, the Lightspeed made the music flow even more freely - there was more detail, greater sense of ambience. Even at low volumes, the music just flowed. Quite remarkable. The staging is wider than my original set up. Bass was articulate, and voices were very life like. Instrument timber and inner details shone.
Overall, I'm a very satisfied customer. Amazing sound at any price. Yet the price is A$470 which makes it the best value component of my system.
Gracerev (System | Answers | This Thread) Very nice system you have there Gracerv. Bricasti M1 DA converter
Esoteric P02 CD Player
Lightspeed Attenuator Lightspeed Attenuator Preamplifier
Krell KAV500 Amplifier
Meridian 861 V4 Surround Pre
SVS PB13 Ultra Subwoofer
Wisdom M50 Speaker
Meridian DSP-6000 Speaker
Meridian DSP-5500 Speaker
Meridian DSP-5500 Speaker
Main System
Pretty much done for now.
Meridian system for Home Theater.
Esoteric/Bricasti/Lightspeed/Krell for CD playback. Thanks for your informed review, you are on my list should any upgrades become availible to the MkII Lightspeed in the future. Cheers George |
Hi Shakydeal, Sonic Euphoria looks to be out of business. I can understand why you like LDR passives, this is the problem with TVC/AVC passives, look at the frequency response of it into 100kohm 10kohm 5kohm input impedance of poweramps. It rings like a bell starting at 10khz! Only into a 1kohm input impedance poweramp does it behave itself, but 1kohm is a severe impedance mismatch, and then it rolls off to early in the HF. http://www.stereophile.com/content/sonic-euphoria-plc-passive-line-stage-measurementsThe Lightspeed Attenuator itself with low capacitance interconnects is flat from 0hz(DC) to mega hertz. Cheers George |
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Hi Roy. Sorry about the delay in answering, I've been busy making them.
There is no advantage in leaving it on 24/7, in fact if it is not used for a while, I "suggest" it be de-powered. As I've only had a couple out of the close to 1000 units made returned that were taken out along with other components in the system due to spikes from storms, lightening strike or brownouts etc..
If it is left on and not used, I do "suggest" that the volume be left at the mid position, as it halves the led (not the ldr) brightness of the series and shunt led’s.
Because if it is at minimum or full, the shunt or series led will be at just below it's maximum full brightness, even though it is said that an led last for tens of years at full brightness.
As for your email regarding if a used genuine Lightspeed Attenuator your looking at is a MkI or Mk11, it can be only a MkII, as all genuine Lightspeed MkI's manufactured earlier were converted to MkII status. There are only clones of the Lightspeed that can be MkI or do not have quad matched sets of led/ldr's.
Cheers George |
05-05-15: Rob_j
So I thought I'd post a bit of feedback now that the LSA has had a couple of weeks of play to settle up.
My regular attenuator is a Townshend Allegri passive which retails for very many times what the LSA costs. Retail price is not a reliable indicator of performance as we know: just setting the scene.
I have to say that the LSA is simply astonishing. It is fluid, extended at the frequency extremes and has a lightning fast attack at the leading edge of notes, then a detailed and realistic decay. Instruments exist in their own space and are distinct from others. There's a quiet confidence to the sound, with a dark background seemingly devoid of interference/noise. No grain, silken and natural.
That's the thing: this really plays music rather than sounding like "good hifi". Music sounds real and involving.
The LSA seems equally happy with Hans Zimmers massive layering and soundstage as it is with Marcus Millers dynamic bass guitar, Army of Mushrooms's bonkers electronica or Jan Garbareks soprano sax. It all works.
In short: Well done George! Overall, the LSA bests the Townshend in my system.
Robert First off Robert, I would like to thank you for your praise and great review of the Lightspeed Attenuator. You are right in that it has extended range as it is dc coupled to almost infinity in speed, hence the name Lightspeed. As for the dark background you mention, it has a far lower noise than any active preamp can be. This is why you get a perfect black background, which aids in greater dynamic range and space around the notes. There will be times you'll think your system is not switch on when your in-between tracks, or when the lead in of tracks have no music content yet. As for your "No grain, silken and natural" comment, there are no "active preamp" component distortions/colourations, what goes in comes out uncoloured and true to the source. Thanks again for your praise Cheers George |
Hi Grannyring, good to see your still loving the Lightspeed Attenuator. It would be nice to get a "sound" difference comparison between the standard wall wart v battery v Teradak power supply. As my a/b's with a group of golden ears showed differences when they knew which power supply was being used. But were also inconclusive when asked in blind a/b tests with the same group, then they said the differences were too close to call. Here is something very interesting that can explain why many say what they say about the Lightspeed Attenuator's superior transparency compare to volume control potentiometers used in most all commercial preamps, active or passive. http://www.diyaudio.com/forums/analog-line-level/80194-lightspeed-attenuator-new-passive-preamp-273.html#post4394156Cheers George |
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Hi Musicmuskrat23, thanks for your very kind words.
As for burn in I do believe that the Cadmium Sulphide component of the LDR does take a while to "form" after it's not been powered for long periods of time.
I've seen this on the scope from new, but it's only a short duration. But in HiFi as you know anything is possible.
As my ESL speakers are big ML's, I've measured them with an ESL volt meter, and they are fully charged within 5- 10mins to 5kv, but I swear they sound better after an hour, at which time they are still at 5kv.
Cheers George
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The Lightspeed attentuator is the first passive volume control that adds real dynamics to the mix regardless of the listening volume. I've had this said many times back to me by Lightspeed Attenuator owners, and asked by them why this is so. These are my beliefs. Try to stay with me with my explanation below. In normal high or low quality volume pots, the source's easily corrupted low level signal has to travel through it. And there is a dimple point contact between the wiper and the resistive track it wipes on. This is very light point of contact on purpose so not to wear out the delicate resistive resistance track. The source's signal has to travel through this point of contact. These pots are also made from two dissimilar materials, the wiper usually being brass and the track another material. This can be the source of a "Diode Effect" And when turned up or down this effect can change the amount of "Diode Effect" and influence on the sound, the lower the listening level the higher impedance part of the track, the more "Diode Effect"?? Imagine the link below as a normal audio volume pot high or low quality. The "screw" being the source input of a pot, the "whisker" being the pots wiper, and the "rusty razor" blade being the resistive track of a pot http://www.electronicstheory.com/COURSES/projnkits/projDiode.htmAs Roymail and other owners have pointed out to me, the Lightspeed doesn't loose it's sonic picture, dynamic ability, and fullness regardless of the level being listened to. To me this is because there are NO light contact points at all in a Lightspeed Attenuator, everything is hard wired and soldered. Also Dartzeel with their $25k NHB-18NS preamp maybe also must think this, as they have used the Lightspeed volume in it, they call it a "Pleasure Control" BTW: Roymail thanks for the great review! Happy listening Cheers George |
Read the above carfully before reading this.
You have a switch on the back next to the output rca's and xlr's that can set the full output level at either 2.5v or 5v, I believe you have it at 2.5v from what you've been telling us.
Quote from a review:Besides the outputs there are also four switches. One selects the absolute phase – 0/180°, the second one controls the overall gain – maximum output voltage of 2.5V or 5V, the third one selects the analog output we use, XLR or RCA. End Quote.
Cheers George |
No nothing going to waste Finn (Andrew) as you have 100kohm input impedance on your amp, so it doesn't mater where the volume is set on the Lightspeed you are getting great impedance matching still over the entire range.
This is a classic quote from Nelson Pass.
(proclaimed god of audio)
"We’ve got lots of gain in our electronics. More gain than some of us need or want. At least 10 db more.
Think of it this way: If you are running your volume control down around 9 o’clock, you are actually throwing away signal level so that a subsequent gain stage can make it back up.
Routinely DIYers opt to make themselves a “passive preamp” - just an input selector and a volume control.
What could be better? Hardly any noise or distortion added by these simple passive parts. No feedback, no worrying about what type of capacitors – just musical perfection.
And yet there are guys out there who don’t care for the result. “It sucks the life out of the music”, is a commonly heard refrain (really - I’m being serious here!). Maybe they are reacting psychologically to the need to turn the volume control up compared to an active preamp."
Cheers George |
I know Grannyring you and Agear love your $6K TRL dude active preamp full of massive coupling capacitors that the signal has to pass through. As you both have come on strong about it very early in this thread once before.
It seems there is a bit of a dude vendetta surge happening again. The late Pubul57 who started this thread warned me with an disturbing eyebrow raising email he sent to me a about you guys before he passed away RIP Paul.
As for Nelson Pass's thoughts on passive preamps, I present to you once again, his quote on the subject in case you missed it before..
Nelson Pass, "We’ve got lots of gain in our electronics. More gain than some of us need or want. At least 10 db more.
Think of it this way: If you are running your volume control down around 9 o’clock, you are actually throwing away signal level so that a subsequent gain stage can make it back up.
Routinely DIYers opt to make themselves a “passive preamp” - just an input selector and a volume control.
What could be better? Hardly any noise or distortion added by these simple passive parts. No feedback, no worrying about what type of capacitors – just musical perfection.
And yet there are guys out there who don’t care for the result. “It sucks the life out of the music”, is a commonly heard refrain (really - I’m being serious here!). Maybe they are reacting psychologically to the need to turn the volume control up compared to an active preamp."
Cheers George |
No, thinking more in terms of power delivery and power supply fluctuations, the ability of the output stage of the CD player to drive the ICs and the amp. |
I first would like to thank Richard also for that very in depth (War and Peace) review, keep up the good reviewing format, I think you may have missed your vocation in life. As for any tweaks that tradeontheweb asked that may have been done to the "MkII" Lightspeed Attenuator since it’s release, it’s still the same save for minor cosmetic changes. Though in the power supply area, "some" have found a small benefit using this power supply to power it, instead of the supplied one. It’s is very nicely made and not too expensive at $44usd, myself I have not heard it, and think it could be a bit of overkill, but in this game who knows, I know it’s 9vdc instead of my supplied 12vdc, but the Lightspeed Attenuator can run on 8vdc to 18vdc no problems. http://www.ab-system.hk/index.php?route=product/product&product_id=64
Thanks again Happy New Year Cheers George
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tradeontheweb
Thanks for the link to the TeraDak, it’s cheap for what you get, I ordered one and will let you and others know what it’s like compared to the standard linear wall wart.
Also how well do you think a battery 12v supply will go in comparison against the standard wall wart or the TeraDak?
Thanks.
You can also try these Li-ion rechargeable batteries, these do have something that is detectable when compared to the linear wall wart. What the difference is no one can quite put their finger on, they just say there is something different. Even Sam Tellig from Stereophile says the same when he reviewed his Lightspeed, same went for his son a guitar teacher with his. What’s really good is, as the Lightspeed consumes so little power, these rechargeable Li-Ion batteries give a good couple weeks of use before you need to recharge them. Worth a try also as they are only $10 - $20 with charger shipped. http://www.ebay.com/sch/i.html?_from=R40&_trksid=p2050601.m570.l1313.TR0.TRC0.H0.XCCTV+12v+battery.TRS0&_nkw=CCTV+12v+battery&_sacat=0
Cheers George |
Hi, this is the one I sometimes use, it's encased in black plastic and is also 6800mAh's which should see around 3 weeks of Lightspeed listening before a recharge is needed, which only takes around an hour. http://www.ebay.com/itm/EU-DC-12V-6800mAh-Portable-Rechargeable-Li-ion-Battery-Pack-fr-CCTV-Cam-Monitor-/151467667559?hash=item23442d3067:g:5UkAAOSwDk5T5Mia There is something about the sound of pure battery power with the Lightspeed you sense something is different compared to the linear powerpack, but you just can't put your finger on it. It's subtle but there, sometimes you can make the mistake of thinking your listening to battery power, when in fact it's being powered by the linear mains power pack. Let us all know the differences you hear of the three different way of powering the Lightspeed?
Cheers George |
Hi hammering, you echo the responses of so many owners when you said. "It simplicity (and price) impressed me so I took a chance and bought one. It has turned out to be one of my better hi fi choices." This "kiss" is the way I like to keep it, to get the source signal to the poweramp/s with the least amount of colourations.
Rather than using preamp circuits, input switching, and volume controls ect, which all add their own set of signatures and colourations. You should also give the $29 battery a try that I posted in my last post, as it is the purest way of powering the Lightspeed and will last a good 3 weeks before a recharge is needed, and please give us an A/B comparison if you get one between it and the supplied linear wall wart.
Cheers George |
I thank you also miller65 for your glowing response to your purchase of the Lightspeed Attenuator. As for your question: "I have however noticed recently the display is showing what I believe is referred to as ripple and varies from 9.20 to 9.23 often changing every second or so , does anyone know if this is normal." This will not effect the performance of the Lightspeed, as for two reasons, the Lightspeed itself also has an internal regulated 5vdc supply it runs on, so any slight fluctuations from your external supply will not have any effect on it’s stability, secondly the 30mV fluctuations you have on the display could be due to slight temp variations inside your Breeze Audio Linear power supply. What you should do is also get the rechargeable battery I posted 2 posts back, as it will be the purest most stable noise free way of running the Lightspeed, and give us your opinion on how you like it’s sound, as for just $28 it’s a cheap experiment, and will leave no room for doubt as well. As we all know audiophiles have doubt if there is a question mark with anything, and it can eat away at our senses sometimes.
Cheers George
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Hi all, owners that like to try different ways of powering their Lightspeed Attenuator’s. May like to try something new that Stereophile gave some push for. It’s the new iFi iPower supply dc wall wart, now before any of you say it, yes I didn’t like recommending smp (switch mode) wall warts. This was only because the ones I tested had a bit of noise, that couldn’t be heard, yet was measurable when compared to a linear wall wart. This new iFi iPower supply wall wart is smp, yet it’s noise is very low. http://www.stereophile.com/content/music-round-77#61wYlEfbAywkfiS2.97 http://ifi-audio.com/portfolio-view/accessory-ipower/ If you order one be sure to get the 12vdc one with 2.1mm X 5.5mm plug with centre positive. Lets please hear a review from anyone that gets one, as I may change to these as supplied wall wart with the Lightspeed Attenuator, as they are multi world wide voltage usable.
Cheers George
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This is what Kalman Rubinson of Stereophile heard when he used this new iFi iPower wall wart on a low powered dac when he compared it to a linear wall wart, it should/could do the same for the Lightspeed Attenuators sound.
"When I switched over from the stock supply, the DAC didn't seem quieter when there was no audio signal, but that's not the real test. Recordings with open, ambient soundstages sounded cleaner, and both instrumental and vocal music was more distinct. This was no major change that struck me every time I listened, but it did make all of my listening much more relaxing—perhaps because, subliminally, it required less effort to attend to individual sounds, particularly those far back on the soundstage."
It has some pretty impressive measured noise figures, of 1uV of noise, (that's microvolt not millivolt)!!!!! This could be a deal breaker, and the end of linear wall warts for the Lightspeed Attenuator. I tried to find advertised pricing of them, but couldn't get an exact figure, but it seems to be around $50-$100 which should be a great upgrade for that kind of low noise supply.
Cheers George |
Thanks banquo, $50 is a very good price if it does what's claimed, can you supply a link to where you got this price, I like to get one when they've replenished their stock.
Cheers George |
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audiolabyrinth
Hi Georgelofi, is it possible to use a light speed attenuator on a phono pre-amp?, I like being different and the first world wide to have such a scheme, if not, can you build me such an attenuator?
Yes it is, I have numerous owners that use it with their phono stages, which say they have never heard their LP's sound so good. First what is the phono stage you are using as there are the odd ones that are not compatible? Cheers George |
Yes I would never advise anyone to put a Lightspeed circuit inside any audio equipment, no matter who made it.
But I don't think @audiolabyrinth wants to do that. He says he want to put a Lightspeed Attenuator "on" his phono stage.
The Lightspeed Attenuator circuit should be by itself, in it's own chassis, and with an outboard powersupply as I make and supply them.
That way the quad matched set of LED/LDR's stay matched, and don't give any trouble at all.
Some of these Lightspeed clones getting around with internal transformer power supplies and other heat generating circuits that give large heat swings are asking for trouble and giving it a bad reputation, careless and I don't advise it or them at all.
Cheers George |
audiolabyrinth
Hi Georgelofi, thankyou, the phono stage that I'm considering is the Vincent pho-700 with outboard power supply solid state/tube hybrid mc/mm phono pre-amp, check it out for me George, audio advisor sells it, has the specifications on their site.
Yes thought it was, saw you posting about it in other threads about it. A very nice looking phono stage for the money, looks like they really did some homework designing this. I found that it is 250ohms output impedance and it has 40db gain for the mm section and 60db gain for the MC section. This will be a great match with the Lightspeed Attenuator. As some of my customers have the Dynavector 75 which has the similar gain structure and they are over the moon with what they are now getting from their LP's using the Lightspeed with it. Cheers George |
