Lightspeed Attenuator - Best Preamp Ever?

Since the resistor changes with the amount of light, could I open the case and use a light bulb with a remote dimmer to change the volume?

Clio9, could you share what those Atma sphere tweaks are?
Tompoodie

No. Please contact Ralph directly. The tweaks may not be applicable to you and your system. Only Ralph can tell you that.

As for a switch box, Decware makes a nice one. I just unplug my cables. Guess I'm a barbarian. The price you pay for the best (IMO) sound.

Are you, or could you, consider making a fully balanced version with some sort of remote volume function?
Koestner

LOL. Been down that road with George, except the remote part. It's hard enough matching LDRs for the single ended version let alone what it would take to match them for a balanced version. Not too mention according to George it might not sound as good or be as reliable as the single ended version.

Let's bear in mind that the reason the Lightspeed is so good is its simplicity. Adding inputs, remote, balanced design, etc. just complicates things. George addresses all this in detail on the DIY.com site where he has been gracious enough to share loads of information. If anyone wants a balanced version I mentioned in a previous post on this thread that George (or I if you email me) will send you a schematic. You could build one or have one built. There is a site (forgot the name but I think its mentioned in this thread) where you can get matched LDRs, and possibly a completed board, leaving you with just the hardware to sort out.

George,

Are you, or could you, consider making a fully balanced version with some sort of remote volume function?

Tompoodie
Also, is anyone aware of a mechanical switching box that would allow one to have, say, 3 rca inputs and one output.

There are many out there here is one. This is the best way as it will still allow you go direct when you want the best out of the Lightspeed.
My prototype has two inputs with the best switch you can get and it is still bettered by every single input production Lightspeed I listen to before shipping out.

http://www.mcmelectronics.com/product/DISTRIBUTED-BY-MCM-INP-3-/50-6170

Cheers George

Clio9, could you share what those Atma sphere tweaks are?
Also, is anyone aware of a mechanical switching box that would allow one to have, say, 3 rca inputs and one output. That would allow one to have multiple source inputs, and still use the Lightspeed attenuator. The alternative is simply unplugging one source, and plugging in another...how barbarian... but worth it to avoid a line preamp.

Proabably getting quite a bit of warmth, dimensionality, palpability, and bloom from the Jadis. The Lightspeed Attenuator doesn't look too puny driving the Music Reference RM10s which are about the size of hardcover book:) - now if I still had my CAT amp....

Sorry to hear that Paul, (please no hate mail) your in good company though, a customer a while ago just sold his $18000aud Matisse Reference pre because of the Lightspeed Attenuator, he invited me around for a listen, it looked ridiculous, here was the diminutive Lightspeed wired up to these 4 x box (coffee table sized) Jadis Reference monoblocks. Boy did it sound good though into the top Avalon speakers.

Cheers George

With Ralph's assistance I'm tweaking the S-30 so that it will be even further optimized with the Lightspeed for single ended use and my Otari reel-to-reel running direct for balanced use.

Pubul57, sorry to see you sold the Joule, I know how much you liked it. If the Lightspeed is that good that you could let the Joule go, then that is saying something.

Thought well enough of the Lightspeed Attenuator, that I just sold my beloved Joule LA150 Signature Edition line stage($6,500,)as having two "real" preamps and a single-source volume attentuator seemed like too much gear, but I'm keeping my Atma-sphere pre for use with the Atma-sphere amps:)

Maybe we can have a giant gaint ?

Goodness that is funny stuff.............

I had to google it, hmmmm.

Grannyring
I have a gaint in my opinion :-)

Good on you Grannyring you've given me my laugh for the day, I'm just a tech with limited English skills I had to look up "gaint" this is what I found in the Urban Dictionary

gaint: loss of blood to the brain due to overly large erection.

Cheers George

I have never heard a stereo system that sounds like live music, but I have heard stereos that probably sound more the recording - the loss goes from live to recording and it only gets worse from their in terms of sounding live. If you don't go to live acoustic events you might get fooled from time to time, but then I go to a jazz concert and after a few minutes my audiophile mind goes ugghhhhh, and accept that stereo systems are just very enoyable ways to a enjoy music, some better than others, and none close to live.

I stand corrected in my Morrison ELAD comments. Thanks for the clarification Georgelofi.

I agree with Pubul57 that for many the straight wire with gain approach is as much a philosophical stand as anything else. I was once one of those folks. Then I became heavily involved with tube amps and preamps and my approach softened. I am aware that a SET tube amp most likely "colors" the sound of most recordings I hear. However,I've made peace with that because I greatly prefer that sound. The issue I have with some "straight wire" proponents is that they can take their stance to the extreme by believing they are recreating live like music conditions via their stereo systems. A quick trip to the symphony is a more than subtle reminder that even the best stereo systems I've heard (Shindo,Audio Note etc..) are nothing more than crude approximations of the real thing.

Like your input George. I would love to try your preamp in my system and compare to my tube preamp. I can't believe I even said this as I am usually 100% against passives based on my experience with these in the past. It's just that several highly respected Agoners seem to think your $450 unit is the real deal giant killer. I have a gaint in my opinion :-)

I have found that my active tube preamp is not a tone control at all. Rather, compared to some nice passives I have tried, like Placette, my music has increased texture, body, stage size, layered holographic presentation and much improved sense of control and utter ease at any volume. All of this while being every bit as transparent.

These attributes have nothing to do with the simple attenuation of bass or treble as a tone control.

I may indeed compare soon. I just can't image a passive unit would match the attributes listed above. If so, your preamp is a wonderful value.

I would guess nearly 99% of good quality cdp dacs have an output voltage of 2v (Redbook Standard) or higher and an output impedance of 200ohms or lower.
Amps may have a input impedance of 47K (industry standard) or higher, nearly all tube amps are 100k or higher and an sensitivity of 1v or higher to clip.

So 2v feeding 1v to clip? no preamplfication needed here

200ohm or lower output into 47000ohm? no impedance mismatch here either.

So if a active preamp tube or transistor sounds better in the above "common" situation it is as Paul says giving the owner the tonal quality they want to hear (less bass more bass) you get the picture.
This however a band-aid fix for that system by throwing in a costly preamp to fix a system problem and at the same time missing out on all the transparency dynamics and sweetness that no active pre can give. Would it not be the wise thing to do and fix system imbalance (different interconnects speaker cable and positioning) problem instead of throwing a costly band-aid at it?
Cheers George

I could agrue that a tone control does nothing for stage size or sense of scale and ease? So I guess tone controls in addition to the active preamp may be reasonable? Ha!

Active preamps are for the most part tone controls (a good case could be made that all components are tone controls as well). A good example to reference is the Audio Horizons thread. A number of people chose to take the very well received stock unit further through modification (whether through the factory options or their own doing). The idea was that they wanted more or something different from the sound of the original unit. Fair game, in a way that is part of the hobby and can be very enjoyable, whether you're swapping tubes, caps, wiring, or whatever else can alter the sound.

What is somewhat amusing to me is that some people want tone controls (bass, treble, etc.) on the tone control itself. I guess a little is not enough in those cases.

We are on the same page Pubul57. Your comments are well thought out and educational.

You can't argue with what people like, which is the only criteria that is important. I suppose the straight wire with gain approach is almost a philosophical stand, even when that might not necessarily result in the most enjoyable sound, a bad recording has no place to hide. This is proabably an issue that can never be resolved, there simply might not be a right or wrong here.

The Lightspeed does minimal (even compared to other passives) alteration to the signal (noise, distortion, bandwidth anomalies) and does this very well, if that is what you are looking in volume control (true to the source) it will serve you well.

Actives can sound better to some because they like the change those tubes, caps etc give the sound. Yes, a good active tube preamp may in fact change the sound and that can be a great thing for some people.

Larger stage size, more romance, or even a greater sense of ease to the music can be (ADDED) by a tube preamp. Some like that.

Arthur Salvatore also says, in an interesting way, that if your systems sounds better, in any way, than a direct connection or passive, then your system needs and active preamp (he says most systems do) - because in some way your just not matched right. AS' views is that passive is the best, unless you need active. I'm pretty sure my system does not need an active for gain or impedance matching and therefore it is unlikely that any active preamp or volume control/gain device will improve over what essentialy (as George points out) is as close as you can get to a direct connection between my source and amp.

If amplyfying that signal through additional wire, capacitors, transisitors or tubes etc, only to attenuate that additional gain can some how improve on the original source signal, I just don't see how it can do that unless that signal needs all sorts of conditioning to drive the ICs and amp. My 2v or 3.9v outputs from the EMM Labs CD player don't need such help to drive the amps, and if there is dimensionality and warmth in a recording it is there at the output of the CD Player, not fabricated in an active tube or SS linestage - and if it is the byproduct of the linestage, I don't want to hear that as it will be an overlay on everything you listen to.

The best sound you will get is to put your (CD DAC or Phono) directly into your power amps with a VERY quite CD track first, this is the most perfect "true to the source" sound you will get...

This is the actual test recommended by Arthur Salvatore to determine if your system is passive friendly and if so whether or not you will like the sound. He recommends Ravel's Bolero as the test track since it starts off with very low volume passages. You need to be careful when conducting a test like this because if you use a track that has a loud volume passage, or even an unexpected loud drum kick, you could blow out your speakers.

Clio09
but the Noble pots, as good as Roger feels they are, will impart a sonic signature.Clio09

This is what I found, all have a sonic signature because of their very soft wiper contact, this has to be a very soft as not to wear out the resistive track it runs on when you raise the volume up and down. This soft contact behaves like a rectifier (diode) trying to convert some of the AC music signal into DC especially the faster transients and higher frequencies. This is why all pots sound different even switched resistor pots, all are a little different in this wiper pressure/material/ & and mechanics, none are perfect as a soldered resistor would be, which is what basically the Lightpseed Attenuator is.
TVC are better here as they do not have wipers, but their problems lay in the 500mts or so of very thin wire the signal has to pass through, this itself is a mine field of current limiting, capacitance & inductance all of which is harmful to the original source (CD DAC or Phono) signal.
The best sound you will get is to put your (CD DAC or Phono) directly into your power amps with a VERY quite CD track first, this is the most perfect "true to the source" sound you will get, and only the Lightspeed Attenuator is closest pre or passive to mimicking that sound.

Cheers George

In the Lightspeed design taking the switch out of the equation further simplifies an already simple design. The Pot in the Box is also a very simple design, but the Noble pots, as good as Roger feels they are, will impart a sonic signature. Transformers and autoformers are wound with lots of wire. I've been watching the transformer winding process and will be learning to do it myself. All that wire has to have some effect on the sound rendering the TVC or AVC less transparent and neutral (silver or copper windings would also have some effect). I can think of two reasons why TVCs and AVCs are popular. One they are more forgiving of impedance mismatches and two, in the case of transformers, they offer some isolation.

I'm considering building a PITB for the fun of it and to compare against the Lightspeed. Also, many people like the Luminous Axiom passive devices. I'd be curious as to any opinions on these from owners. Come to think of it I've got a pair of EVS attenuators lying around I should throw in the system for the fun of it.

In regards to comments on the Morisson Elad.

I too read the hype a few years ago and searched long and hard to find one. I then had a custom power supply built to suit our 240 Voltage here in Australia.

I had it in the system for several weeks, constantly A-B'ing against the LS. The best overall description I can give the Elad was it just sounded "duller" in all areas. This was irrespective of cabling lengths or impedance matches/mismatches.

However, I sold it to an aquaintance who still uses it to this day and actually prefers it over my LS, in his system !

As stated elsewhere, the LS is not for all and can be a harsh taskmaster indeed. It will make you "lift your game" and requires your whole system to be in order, to show it's best.

Easily worth the effort - IMHO

Lightspeed Attenuator, Best device for controlling volume in an audio system ever? including "real" preamps?

I still say it's not a preamp! Any direct comparisons to other real preamps are somewhat misleading. Kudos to the designer/manufacturer for calling it what it is.

Anthony, Roger Modjeski was gracious enough to explain to me why he thought resistor passive would be theoretically better than tvcs or avcs (the Audiogon consensus was that TVCs were far better than resistors, that TVCs 'blew them out of the water - which always seemed an overstament), but you know how he gets with technical explanations, he quickly lost me. When I had the Placette I like it very much, and I do think it might be fruitful to go back for comparison, but I suspect that the fact the Lightspeed has no physical contact points, no mechanical interface, no oxidation, no wearinmg out with time and swipes, might be an unbeatable advantage, even for Swiss crafted, jewel-like, precisely machined or lazer edged attenautor contacts:)

Sorry, itchy trigger finger.

For some time I had been a big proponent of transformer based passive designs. The Lightspeed changed all of that and the idea of the thread was to really extol the virtues of resistive designs - done right IMO. Yes they do require more finesse in system matching than a TVC or AVC, but overall I think a well designed resistive passive is truer to the sound. Makes me want to go back and listen to a Placette again, I may have dismissed it to soon.

What I find with the LS is that the issue of soundstaging, dimesionality, apparent bass and highs, etc. is dependent on the recording, and for my approach to building as system, this is the way it should be...

To Pubul57's point, I've been hanging around a recording engineer of late. His system uses SET amps, a passive, preamp, and some pretty good source equipment and speakers. The speakers were placed against the back wall. One would think sound stage depth would suffer, but it didn't. It was however recording dependent and to his point, much (if not all) of the sound staging comes from the recording itself. I tried this at home with my own speakers and found it to be true. Amazing how much space I've created for stuff other than listening now that my speakers are nearly in the corners of the room.

I think equipment that is true to the source will provide the proper sound staging - regardless of whether they are active or passive designs (in the case of preamps). It really does come down to preference, but I know I'm not going back to an active preamp anytime too soon.

Pubul57 yes I owned the Bent TVC and it was excellent but lacked the low end and mid bass slam that the LS delivers. I like you tried different passives all good but not as good as tubed or SS pre's I own or owned. With the LS In the system I found the perfect match that I am happy with.

La45, yes this was the one I started using a while ago, around Thanksgiving last year. A while back I started a thread called Slagle AVC Modules & Lightspeed Attenuator.

Fazoid, I think you had the Bent TVC? An very good passive preamp. I've had Placette, S&B TVC, and Bent/Slagle autoformers, and a few others. While I thought they were all exceptional values with excellent sound, I nevertheless, ultimately preferred my active tube preamps that I owned at the same time. The LS is the first to make me think I may not need them anymore, though I may keep them for the same reason I keep 3 amps, I like audio gear:). This is not a poor man's preamp, though it is affordable to many, it is actually pretty expensive for what it is in terms of parts, but what you pay for is years of perfecting the basic idea and the painstaking matching of the components to get proper balance between channels. You could, I suppose build one of these with George's instructions found on the DIY boards for less than $100, for some of you with the skills that may be an option -- I'm sure I would manage to start a fire.....

Sibelius I have heard in my system the Morrison Elad and it is not in the same league as the LS. The other preamps I mentioned in an earlier post are all excellent passive's the LS is simply better.

Faziod Hi you will hear very low level of music at minimum level as this is the characteristic of ldr's in this design is they can never go to complete darkness or infinite brightness as these are the controlling factors for resistance. Think of it as there is no such thing as infinite brightness or infinite darkness.
Cheers George

The Morrison Elad is just a normal active preamp using normal pot and a 50 cent Analog Devices AD797 opamp with no gain.
It has nothing what so ever in similarity to the Lightspeed Attenuator and it has nothing what so ever to do with LDR's or LED's.

Cheers George

George, why is it that I can hear music still playing with the volume all the way counterclockwise?

Clio09

So this was the 'passive' preamp you started using. If not for this thread, folks will dismiss the LS as a poor mans preamp and miss a great opportunity to discover its musical attributes.

Thanks Pubul57 for exposing it to all of us.

Apparently something like this was once used in the Melos preamp years ago, and in the current DarTzeel (something like it).

I finished my last post by saying try it, since it is almost impossible to avoid cliams of overhype when talking about a preamp most have not heard, and lord knows there have been many flavor of the month, buzz pieces that are long forgotten shortly thereafter. So all I can do is recommend you try it if it might fit your system.

I only offer the context of my views, as a previous owner of many passives that left me feeling like those here that have expressed dissapointment with there efforts at using a passive. First of all I have owned almost every passive of the past five years of all the basic desing approaches and always preferred my active tube line stages. As an interesting point two of the folks that like the Lightspeed have also owned Joule preamps which are on the warm, musical, meaty, organic, etc side of the preamp spectrum, so we know that sound, and in that context, the LS does not dissapoint - it is not cold, sterile, lifeless, flat, missing PRAT, etc. Now, I don't know how to address the warmth issue, since two of my favourite preamps are the CAT SL1s and Atma-sphere and they are not known to be "warmth-lover" preamps, so it may be I don't find warmth as seductive as others, though I do love my Joule LA150 Signature Edition which is warmer than the other two.

Yet one cannot predict how each of us might react to this thing, which is why I say you have to try it and decide for yourself, if it was $5,000 I would want alot more evidence and listening sessions, but for $500 it is within reach of most of us in the forum to decide for ourselves without coming to conclusions drawn from sources other than our own ears.

Best preamp ever? I do think that is a silly question, or at least silly to believe such a thing exists, it does not and cannot. But, the Lightspeed is very, very good, and sound like this from a $5-10,000 preamps (the price of my last five tube preamps) would be great, at this price it seems like a must audition, at minimum, for those on a budget with something like a Music Reference RM10 (1k-2k - used/new) and 89/90db or higher sensitivity, flat impedance speakers for a first rate system at an "affordable" price. For those with plenty of $$$ to spend, at this price it is simply worth trying for yourself and draw your own conclusions.

Even if it does sound as great as I (and others that have heard it/ owned it) am saying, it still will not be the preamp for everyone, since it is VERY limited as a source selector, and does require a source, short (2m) ICs, and amps that can work with a passive - not all can. Just as I would not make claims about 4 watt SET amps sound like from listening to them on a pair of B&W 802s or Thiel 3.6s - I exaggerate to make a point.

If you live near Baltimore, come over for a listening session and compare it with my Joule and Atma-sphere setups and tell me what you think, easy enough to compare.

I agree with Dividedebytube (interesting username)

Can this be used as part of a glorious active tube preamp? This would be the attenuater part? My very strong hunch is this unit will end up falling short of my current active tube preamp for the same reasons given by Fiddler.

For those of you who have been around the boards a long time, this looks very much to me like a much hyped passive preamp of old called the Morrison ELAD. I remember the buzz - the ELAD was the closest to "straight wire with gain" that you could get. I bought one. Well built but sonically did nothing for me. Fast but cold. No emotional connection. However it was good lesson. I learned that I prefer the warmer sound an active preamp over uber transparency.

I have not heard the lightspeed so I don't want to be critical. I hope its owners are happy. I will say that the price point makes it attractive to try out. $500 these days in audio is not much of a gamble. Just seems like we may have been down this road before.

I have a passive in my system now based on a 50k tkd attenuator. I don't hear any obvious problems whereas when I had Endler type attenuators in the same system and interconnects there were obvious frequency anomalies. So how can one predict whether the Lightspeed will be an appropriate match?

I would like to build one, but include an output buffer (tube or FET) for driving long cables or low impedance loads. Of course a little gain wouldn't hurt either - especially for low sensitive amplifiers or if using a low MC cart (etc, etc).

I know this destroys the purpose of a 'passive' preamplifier - but I've never heard a passive that I've liked long term.

My interest in passives started when I read on Arthur Salvatore's website "if your source is up to the task of driving your amp(s), then no active linestage, no matter how good it is, will ever equal the sonics of your direct connection (or an equivalent passive)". This coming from a tube-centric audiophile made me ponder this for a long time. He goes on to describe the circumstances under which an active linestage would be needed. I read this and left this continuing with my various tube linestages, not sure if it was warmth I was looking for, but certainly dimensionality which I always found lacking in SS preamps.

Then I bought a couple of amps from Roger Modjeski, the Music Reference RM9SE and RM10s. Knowing he could design anything he wanted to, I noticed that he made the move from active tube linestages to passive and asked him why, this guy obvioulsy loves the sound of tubes, not only making gear with tubes, but also the best tube tester on the market, and he said just what Salvatore said, no active line stage would be better than a high-quality pot based passive with his amps (100kohm input, and high sensitivity). Asked about buffers, tranformers, blah, blah, and he said I can make you whatever you want ("I'll put a tube or two in it if it makes you happy"), but he repeated, nothing will be beat a passive preamp with no buffer IF mathed correctly between source, cables, and amp.

As to Fiddler's comment on warmth and dimensionality, I have to say we all want dimensionality (as long as it doesn't come at the expense of timbral accuaracy)and in this aspect I do not feel any loss of this important aspect compared with my Joule and Atma-sphere preamps. The area of warmth is a little more difficult to put my finger on, perhaps more subjective, and prone to the influence of preference. I will say that he idea of "adding" warmth is not something I am comfortable with, but that is just me, with the LS I feel I am getting as much warmth or lack of it as is in the source. The apparent warmth will vary with the recordings, and that is a very good sign to me, that is when the sonic attributes of a piece of gear change, or is dictated, by the recording - it tells me the gear is not putting an overlay over a recording that can be heard regardless of what one might find in the recording itself.

What I find with the LS is that the issue of soundstaging, dimesionality, apparent bass and highs, etc. is dependent on the recording, and for my approach to building as system, this is the way it should be, but that does not mean it is eveyone's cup of tea regarding the sound they are looking for.

But, these are all words, which don't mean a thing compared to trying one of these things in your system, knowing, and accepting, its ergonomic (one input/output) and electrical (gain and impedance matching) limitations, and judging for yourself.

For members who wish to know how I started the Lightspeed Attenuator project, a small portion of the history is available on this Audiogon post.

http://forum.audiogon.com/cgi-bin/fr.pl?aamps&1275616047

Cheers George

Best preamp ever by DEFINITION is the ONE that matches your poweramp.

There is another LDR preamp on the market called Lighter Note Preamp but it's DIY mostly but costs I think around $170 for the kit. But you can get the PCB populated by the designer for a little more. All you have to do is get the chassis, RCA, and knob and put it together. I think a fully built unit is in the future but don't know the cost. I heard this at the Lone Star Audio Fest and was surprised by it's sound. I've had passives in the past based on DACT and Alps pot which were detailed but thin sounding, but the LDR was surprisingly full and smooth and detailed at the same time-sounded like the best of tubes without the draw backs. Any way I have a Bent Tap X on it's way and will also get and LDR preamp to compare for myself.

I love my Lightspeed, but it is not in my system for one simple reason. My Supratek Chardonnay is equal to the Lightspeed in all regards; transparency, slam, finesse, soundstage, etc., but my Chardonnay is not stock. It has a DACT attenuator and VCaps, both of which added much greater transparency. I also use WE 350B's that take the Chardonnay to another level, IMHO.

The only thing the Lightspeed can't do that my Supratek can is to add the 3 dimensionality and warmth of tubes. That speaks volumes considering the Lightspeed costs only 500 bucks. But regardless of price, the Lightspeed is phenomenal.

Hi fellow audiophiles, first off let me thank you Paul for starting up a Lightspeed Attenuator thread as writings about it were so scattered amongst the other non descript threads, it would have looked sus if I had started it.
I have a simple website at www.lightspeedattenuator.com and you can also access it via the Audiogon manufacturers listings.
If any of you would like a PDF sales/pricing/shipping brochure you can pm me via this forum with your email address and I will send it to you.

Cheers George