Lightspeed Attenuator - Best Preamp Ever?

George built one for me a couple of month ago. It is by far the best attenuator I have ever used in my system.
Great depth and open soundstage.
Very lively with tons of attack.
Thank you George, the Stereophile recommendation is spot on.
John. (JW Audio)

For those who want an integrated amp or preamp with a LDR controlled type of volume control in the designs.
The Japanese company Arte Forma Audio have used (I'm not sure if correctly used) a form of the Lightspeed Attenuator in their Susan and Susan MkII integrated as well as in their Perla preamp.
Correctly they have refrained from inserting it into their tube products, because they probably have found that the fluctuating heat environments within tube products leads to an LDR type volume control not be able to stay in calibration.

Cheers George

George, are you saying that a DIY guy like me really cannot place an LDR volume control in a tube preamp. It would be interesting to compare to a nice Shallco stepped attenuator.

Would LDR actually sound better then a Shallco in a top notch active tube preamp. Interesting idea. You seem to think the heat in a tube pre may cause problem?

Anyone can put one in a tube pre or tube power amp, but the temperature fluctuations will make it go out of calibration very quickly.
Comparing the Shallco to the Lightspeed in a preamp where there are no switches or balance controls, in other words no other switch contacts that the signal has to travel through. The Lightspeed will sound better than the Shallco.

Cheers george

Last question. What temp fluctuations are you assuming in these cases? How hot? Over 90 degrees F? Thanks...

It's more that if you calibrate for ambient ie: 15c to 35c that's ok, but when the tubes and their transformers can add another 40c or so to that ambient inside the chassis, the ldr's will need to be recalibrated to that temp.
Where in the production stand alone Lightspeed Attenuator there is nothing inside the case to add to whatever the ambient is, so it stays in calibration, unless someone sits it on top of say a Pass Labs XA***.5 class A amp,then your asking for trouble and the same will happen to it.

Cheers George

When I take temps in my preamp (tube) I have never read temps any higher than 90 - 102 degrees F. If the room temp is 75 degrees, then I assume no issue?

For cost and hassle reasons the thought of an LDR is very interesting. Shallco attenuators are very expensive and a lot of work. They sound fantastic and I must admit doubt that a low cost LDR would sound as good.

But, I have never directly compared in an active preamp and am open to trying. If it sounded as good, then it would be a nice alternative for sure.

Not sure if anyone has done this type of comparison in an active preamp. Hard to do without having two of the same preamp for comparison. I suppose one could solder in and out the two attenuators, but going back and forth would be a HUGE hassle.

I believe Audiogon member Dgarretson put an LDR volume control in his Atma-Sphere preamp. In fact he may have mentioned it in this thread somewhere. You might try pinging him.

Thanks Clio09. I will check with him and his results.

Clio09,

As an FYI. I now own a Music Reference RM9 MKII that I modified with Duelund CAST caps. Based on comments from you and others I thought I would try it. I love this amp! Very musical and engaging.

Clio09, Thanks for remembering. I replaced a balanced Shallco attenuator with a 100K balanced LDR attenuator in my AtmaSphere MP-1 phono preamp with great results. It is a relatively simple project, provided that use of LDR is limited to the shunt position in conjunction with a high-quality fixed series resistor such as TX2575. One of the many nice things about this application is that the useful range of attentuation across the full arc of the dual control pot can be varied to your desired gain structure by varying the value of the control pot. To obtain a range of attenuation between around -70db and -30db I used a 500K control pot with dual 50K trim pots for L/R balance. Depending on ambient and chassis temperature one must occasionally rise from the couch to trim channel balance. The improvement in sonic performance is well worth the effort.

Dgarretson, your the Man! I just looked at your system with all the mods. Very nice job indeed. I have started the whole DIY thing and am learning.

I would love to visit with you on how to try the LDR mod as well as how you made your speaker cables. I have heavily modified my speakers to great effect and completed a tube amp project by gutting a tube amp and building it back up with better parts and improved power supply. I had direction from a tube amp expert but did learn a lot. I was very excited to view your system and work.

Bill, want to hear something funny. You bought your RM-9 from my friend Warren.

Small world indeed.

Grannyring, Feel free to PM me for the speaker cable recipe or for ideas about implementing LDRs in a volume control for an active preamp. davidgarretson@verizon.net

I've had my Lightspeed several months now and just tried something that gave me a great improvement. I've had the wall wort pluged into my dedicated ac line. I pluged it into my ballanced power conditioner and it made a huge improvement. The improvement was as good as when I pluged my cd player into the conditioner. More 3 dim. soundstage, better separation of instuments, lower noise floor etc.
I'm now thinking of trying a 12v battery supply to power the LED. Has anyone else tried a ac cond. or batery supply and if so, was it an improvement for you ?

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

I do not prefer the battery. I cannot say exactly why but with the battery it sounds a bit lifeless and more clean. Without the battery it sounds more vivid. Probably I like the result of a "dirty" power.
Regards
batalok

I prefer the battery but like George cannot put my finger on exactly why.

My LSA has arrived it now does volume control for my Esoteric X-03 into a pair of tube Acoustat servo amps on my Acoustat X speakers.
Previously I was using the line inputs of my Manley Steelhead into the Acoustats.
The walwart is plugged into a Hydra 8,which is connected by a Shunyata Annaconda power cord into a FIM recptacle on a dedicated 20 amp line.The Acoustats are on another 20 amp line using more Annacondas into a Furutech GDX-gold receptacle.
The esoteric has an Annaconda digtal power cord going direct into the FIM 's other receptacle.
The LSA sits on 3 roller blocks atop the hydra and is plugged into one of the Hydra's digital recptacles.

Sorry about the long winded preamble, but if Iam doing something amiss in my set up, please advise me so that I can correct the error of my ways.

Now to my intial impressions.
After only a couple hours of listening,it's easy to hear the increased amount of detail.
The issue of volume seems to vary from cd to cd , something I hadn't noticed when I listened to cd prior to the LSPA.
I tend to listen at more modest levels,so the volume control is the lower side of 9, but this is not a problem, I'll take added detail retrieval as the trade-off.

There seems to be some extra lower bass punch on some cd's that I didn't notice before, and on some other cd's I felt there wasn't as much.
That's strange.

My intial take is that the Lightspeeed doesn't homogenize the sound as much as it was before, but not to discredit the Steelhead in any way.It's just that the differences between cds are more noticeable than before, or maybe it's my imagination?

Also, I had two wal warts to experiment, one had variable plugs and voltage settings, the other was fixed.
The fixed walwart was the more robust, the other a bit more edgy, zippy, depending on the cd this could be a mixed blessing.I stuck with the fixed version.

This leads me to speculate on how sensitive the Lightspeed is to what it's power by.
I run it into the digital receptacle of the Hydra 8, but will try one of the analog receptacles.

I too wonder about what battery power would sound like after my initial runs with the two different wall warts.
I've just read George's reccommendation,a bit late as I just sent him my take on the unit before coming to this thread.

Am I happy with the Lightspeed?
Definitely yes,for the money it is great,and the single input isn't a drawback,there's better isolation between sources this way(one reason why I wanted the cd player out of the Steelhead)maybe just a minor inconvenience,as is the lack of remote volume is for others.
Personally I'll take it as it's served up,all the better for the sonics.

I look forward as the hours pass, to judge whether the sound improves , but so far I am very pleased.

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

Thanks George for confirming that what I was hearing wasn't my imagination.

I've been on a "power first" approach to this hobby for the last few years,so it doesn't surprise me that the quality of the wall wart could affect the sound.

I hope to explore some alternatives,some of which
are twice the cost of the Lightspeed, but I'm no stranger to using ancilliaries that cost more than the components they are plugged into.

I feel your product is more than deserving of the best power they can get.
Perhaps something from you in the future?

From a weight perspective, the heavier one, the one with the ability to switch plugs of different sizes and switch values is the heavier,but it has the zingy sound.
But I'll try it again and see if I change my opinion now that the LPS has aged somemore.

What I really find interesting is how we ,audiophiles,seem to have a preference for colourations.
We all seem to want to find the special poridge that is just right,but that means something different to everyone.

Tube vs solid state,it's all colourations, trade-offs and preferences.Over the years we tend to find gear that is a comfortable fit,like a nice pair of well fitting shoes that we've grown accustomed to.
New shoes seldom feel the same as the old ones did,until they too are near their expiry date or fall out of fashion.

Audio gear is much the same.
What's new is either embraced or scorned,it's a revelation or it's snake oil.
It's just a re-badged version of something that came before it, or it's just not as good as they used to make back in the good old days.

But sometimes something does come along that seems to be out of step with what's been going on in audio over the last few years.

A product that sounds way better than it's price would lead you to believe.
A product that really doesn't fit into either the tube or solid state camp, and one that doesn't have as many sonic colourations as some of the best of each.

This I find is the most impressive characteristic of the LPS.
It just gets out of the way and lets you hear more of the cd and less of what the pre-amp is adding to the sound of the cd.
It's like a pre amp - not.

I'm not a newbie,here's a few of the pre amps I've owned,in different systems however.
Dynaco,RGR,Mark Levinson, CJ Premier 2,Audio Valve Eklipse,
Sonic Frontiers, Blue Circle Galatea,and I know I'm leaving some out,but perhaps there's a reason why I've forgotten those.

Everyone of those preamps were good, at least to my ears, and so is my present pre, the Manley Steelhead,which replaced a Sutherland PHD, which was no slouch either, but only a phono stage.
But they all had a "sound" which they imparted on the music.
I never really knew how much of a sound most highly regarded preamps have until I heard the LSP.

I'll have to rehash the old war horse terminology of "hearing things for the forst time in my cds", but that's an apt description of what the Lightspeed Attenuator does for me.

If you have assembled a decent system and you want to hear what those components really sound like, as oppossed to how they sound with added colourations, then I think you would be as pleased as I am with the Lightspeed.

I got George Lightspeed attenuator directly from him and is using with my Bryston 3bsst . earlier I was using Luminous Audio Axiom walker modded Passive Pre. In short , there is lot of improvements in terms of transparency of sound . Overall sound is also more smooth on ear .
Highly satisfied owner .
Thanks George for such a wonderful product at a budget price.

I just recieved my lightspeed this morning. First off, George does great business. He e-mailed me back three or four times a day in the beginning in order to answer any and all of my questions. Second, he over delivers on his promises. I was expecting it would take 5 to 7 weeks for me to recieve my lightspeed and it took about three weeks.

Now, for the sound. Talk about transparent and detailed! My system had some grunge, a little bit of mid range mud I guess you could say. Well it's all gone; all of it. My sound is so clear and transparent that if I had to stop here with the upgrades, I'd finally be satisfied. Everything from here (power cords, isolation footers for my components, more room treatments, analysis plus interconnects), it's all icing on the cake. I have finally got the sound I was after.

This "pre amp" is worth it's weight in gold. Don't buy one, buy two and give one to a friend. I'm serious, they're that good.

Thanks again, George!
:-)

Yep, another "normal" comment from a first time Lightspeed Owner !

Mine's coming up to it's 7th year of use now. Still haven't found aything to beat it for a single input Attenuator, when correctly implemented.

Cheers

Scott

I use two short pairs(1.5 Mtr) of Heimdal from my source to the Lightspeed and from it to the power amps.

I was running a longer pair of Art Audio IC from the source.

I think I like 2 matched pairs.

I'm curious about future IC upgrades.

So what's the latest rave interconnect for the Lightspeed?

Two pairs of the same or mix and match?

I'm curious about that too. I'm using two matched pairs of blue jeans interconnects that sounded like poo between my dac and classe pre amp, and between my classe pre amp and classe amp. For dome reason, they sound fantastic with the lightspeed. I can't wait if it will sound better using some analysis plus or signal cables :-)

Hi B_limo (Bruce) , thanks for the very concise and accurate review of your new Lightspeed.
As for interconnects with it, it is always good to use good quality low capacitance ones from the output to the poweramp, as is the same for tube preamps, <100pf (picofarad capacitance) per foot is fine.(which most hi-end cables are).
Manufactures should be able to answer this, or have it printed in the specs on the packaging.
The input interconnects from the source can be whatever good ones you have handy and like the sound of.
As for the brand/construction this is more system dependent, I for my system prefer copper, some may like silver, which to me is always a tad brighter.

Cheers George

TelWire from source to LSA and Mogami from LSA to amp.

TelWire (pure copper?) Mogami (pure copper?) This is what I use as well (99.99% copper) but different manufactures, no multi fine strands, but a couple (4-6) of good size solids cores per phase, this combo give me power heft and tightness as well as transparency through the mids and highs. And of course low capacitance.
I've tried silver at either or both positions, while initially impressive they quickly sounded too highlighted in the upper ranges, not harsh but highlighted, it was quickly obvious that it was disjointed from bass/mid bass to the mids and highs, in other words it didn't flow.
For speaker cable, for my bass (ACI SV12 IB 4cuft 150hz to 20khz) I use again 4 x solid core per phase 99.99% copper.

Cheers George

For some reason the last paragraph got edited this is how it should read.
For speaker cable, for my bass ACI SV12 IB 4cuft 25hz to 150hz I use 4 x 1mm solid core silver per phase.
Then for the ML ESL's 150hz to 20khz I use again 4 x 1mm solid core per phase 99.99% copper.

Cheers George

TelWire is solid core copper, the Mogami stranded copper. I made a set of speaker cables using 1 x copper solid core combined with 1 times silver solid core per run.

Congrats Adam Scott!

George: Forgive me but what I'm about to ask has been mentioned 100 times in this thread but I guess I just want some reassurance. I'm about to purchase a solid state amp with a 51,000 ohm input impedance and a .75V input sensitivity. My dac outputs 82 ohms and 2V. I'm also thinking about buying a TVC preamp while used, is still considerably more than your preamp. I listen to classical and jazz at moderate volume levels at most. Is the 51k of my next amp adequate, or borderline for my listening habits?

By the way, I'm a former LSA owner who was THRILLED during entire time of ownership. However, that was with an amplifier with almost a 400,000 ohm input impedance!

You will be fine with those specs. I have used the LSA with an amp with a slightly lower input impedance and the sound was just fine.

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

Thank you both for responding.

Clio09: I know you said the sound was fine, but did you have ANY issues with limited dynamics, or felt at any time that you were "borderline" regarding dynamics? As I said, my listening volume is on average fairly low, but I still want the low level detail and weight that I get at lower volumes.

George: Since I'm kinda close on specs for the LSA not losing any of its magic, I want to squeeze as much out of it as possible. I want to find the lowest capacitance interconnects I can. May I ask what you recommend?

Again, thank you both. No offense to anyone else on this wonderfully informative thread, but you were specifically the two gentlemen I wanted to here from!

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

No loss of dynamics from what I could tell. I think you will once again discover why the LSA is so good. The ICs I used back then were Mogami but now I use WyWires. They have incredibly low capacitance.

Dealer disclaimer for WyWires.

Lightspeed Attenuators owners and diyer's, I've just been informed again by Stereophile, and you'll be happy to know that your Lightspeed has just made it again into the Recommended Components with the highest 3 x $$$ rating for sound and value for money in the next issue.
You can download it free via Apple Ipod from the Stereophile website or wait for the hard copy to come out.

Cheers George

Thanks for the update and congratulations.

This forum is dangerous.

I just ordered one as I always wondered about removing the preamp but never acted on the thought until this forum and at this sane and reasonable price, it is a good calculated risk to take. Really curious about this one.

How could Photonman not own a Lightspeed???? Seriously, it's a great product. If you don't need source switching, it probably IS the biggest bargain in high end.

Hi, My question is for eany one who may be of help, can this lightspeed atenuator work with a krell class A 700cx amp that is 3.3 volts input sensativity, and 100kohms????, thanks guys!

What is the output voltage and output impedance of your source? That will give us a better indication. FWIW I use my LSA with an Atma_Sphere S-30 which is about 3V sensitive and 100k ohm input impedance. My source is Just over 2V output and 100 ohm output impedance. Works just fine.

@ clio09, Hi, I am currently useing a Ayon cd-2s digital player, It is 300 oms out-put, and the out-put voltage is switchable 2.5 low to 5 volts on high,, I keep it on 2.5 volts to run directly to the krell 700cx, the krell is 3.3 volts in-put.,, The Ayon has 3 R-core transformers inside of it, one for each channel after the signal leaves the out-put tubes, and the other R-core transformer is for the digital.,, thankyou.

Should be no problems, try it on low first you should have enough seeing you have at the moment with it direct. Then if you need to push it harder try the 5v.
As for the impedance of 100kohm on the Krell this is great, as with the Lightspeed which mimics a 10k pot you'll have a combind Krell plus Lightspeed load impedance 9k which the 300ohm source output will see which should also be fine.

Cheers George

You should be just fine. Especially if you can drive the Krell direct from the Ayon.

Thankyou gentleman!, The main reason I am interested in the Lightspeed is running the Ayon direct versus having a pre-amp sounds to forward for my tast!, most people do not have this problem with the ayon 2s with a pre-amp!, To me, running the Ayon 2s exploits the true nature of this player, And I have to say, I hate a forward sound!, I was thinking that the Lightspeed would act like some sort of buffer to rid the forward sound, now, thats if the Lightspeed itself is not forward sounding!, where do I buy the Lightspeed?, How does it compete to the tvc?, witch do you guys think has the better sound?,, Thankyou, cheers!

You can buy the Lightspeed directly from George. Email him at georgehifi@optusnet.com.au. Also, check out this thread regarding a comparison I did between a few different passive/buffer units:

http://forum.audiogon.com/cgi-bin/fr.pl?aamps&1248137240&read&keyw&zzavc

http://forum.audiogon.com/cgi-bin/fr.pl?aamps&1286153678&read&keyw&zztruth