Thank you.
Lightspeed Attenuator - Best Preamp Ever?
The question is a bit rhetorical. No preamp is the best ever, and much depends on system context. I am starting this thread beacuase there is a lot of info on this preamp in a Music First Audio Passive...thread, an Slagle AVC Modules...thread and wanted to be sure that information on this amazing product did not get lost in those threads.
I suspect that many folks may give this preamp a try at $450, direct from Australia, so I thought it would be good for current owners and future owners to have a place to describe their experience with this preamp.
It is a passive preamp that uses light LEDs, rather than mechanical contacts, to alter resistance and thereby attenuation of the source signal. It has been extremely hot in the DIY community, since the maker of this preamp provided gernerously provided information on how to make one. The trick is that while there are few parts, getting it done right, the matching of the parts is time consuming and tricky, and to boot, most of use would solder our fingers together if we tried. At $450, don't bother. It is cased in a small chassis that is fully shielded alloy, it gets it's RF sink earth via the interconnects. Vibration doesn't come into it as there is nothing to get vibrated as it's passive, even the active led's are immune as they are gas element, no filaments. The feet I attach are soft silicon/sorbethane compound anyway just in case.
This is not audio jewelry with bling, but solidly made and there is little room (if any) for audionervosa or tweaking.
So is this the best preamp ever? It might be if you have a single source (though you could use a switch box), your source is 2v or higher, your IC from pre-amp to amp is less than 2m to keep capaitance low, your amp is 5kohm input or higher (most any tube amp), and your amp is relatively sensitive (1v input sensitivity or lower v would be just right). In other words, within a passive friendly system (you do have to give this some thought), this is the finest passive preamp I have ever heard, and I have has many ranging form resistor-based to TVCs and AVCs.
In my system, with my equipment, I think it is the best I have heard passive or active, but I lean towards prefering preamp neutrality and transparency, without loosing musicality, dynamics, or the handling of low bass and highs.
If you own one, what are your impressions versus anything you have heard?
Is it the best ever? I suspect for some it may be, and to say that for a $450 product makes it stupidgood.
I suspect that many folks may give this preamp a try at $450, direct from Australia, so I thought it would be good for current owners and future owners to have a place to describe their experience with this preamp.
It is a passive preamp that uses light LEDs, rather than mechanical contacts, to alter resistance and thereby attenuation of the source signal. It has been extremely hot in the DIY community, since the maker of this preamp provided gernerously provided information on how to make one. The trick is that while there are few parts, getting it done right, the matching of the parts is time consuming and tricky, and to boot, most of use would solder our fingers together if we tried. At $450, don't bother. It is cased in a small chassis that is fully shielded alloy, it gets it's RF sink earth via the interconnects. Vibration doesn't come into it as there is nothing to get vibrated as it's passive, even the active led's are immune as they are gas element, no filaments. The feet I attach are soft silicon/sorbethane compound anyway just in case.
This is not audio jewelry with bling, but solidly made and there is little room (if any) for audionervosa or tweaking.
So is this the best preamp ever? It might be if you have a single source (though you could use a switch box), your source is 2v or higher, your IC from pre-amp to amp is less than 2m to keep capaitance low, your amp is 5kohm input or higher (most any tube amp), and your amp is relatively sensitive (1v input sensitivity or lower v would be just right). In other words, within a passive friendly system (you do have to give this some thought), this is the finest passive preamp I have ever heard, and I have has many ranging form resistor-based to TVCs and AVCs.
In my system, with my equipment, I think it is the best I have heard passive or active, but I lean towards prefering preamp neutrality and transparency, without loosing musicality, dynamics, or the handling of low bass and highs.
If you own one, what are your impressions versus anything you have heard?
Is it the best ever? I suspect for some it may be, and to say that for a $450 product makes it stupidgood.
1,866 responses Add your response
I want to add my very positive initial experience with the Lightspeed here. After receiving some good advice on amp input voltage here, I purchased and plugged in the LSA into my system about a month ago and am very impressed with it in terms of: 1) detail - every recording I listen to now has added lines, inflections and colors; 2) color - the diversity of sound colors I now hear is maybe the biggest single change I've experienced. I listened to Philippe Herreweghe's sonically-excellent recording of the Mozart c-minor serenade for 8 wind instruments soon after getting the LSA. It was like listening to a kaleidoscope of timbres, with each of the instruments differentiated by register, type of attack and dynamic. Amazing. 3) musicality - this is maybe the most surprising effect, for which I was totally unprepared. The performers actually seem to be more "human". There's also a "spaciousness in time", in that the melodic lines "breathe" more (boy, is writing about music hard). My working hypothesis is that this is a result of the added detail: one can now hear more of the inflections given to the notes, especially during the initial attack, and this decrease in blurring at the transient edges of sound adds ease and expressivity to the music. So I want to thank George, Pubul and Clio for turning me onto a component that is the end-state for my system (off the merry-go-round!). A few technical comments: 1) With my 1.8v DAC feeding my 2.1v input amp, I find most of my listening to be in the 12-2 o'clock range. 2) I swear there was some break-in in the bass with the LSA, lasting maybe 5 hours. 3) I am a newbie compared to the very experienced audiophiles here. I think suggesting a DAC/passive preamp/high impedance amp combo is a must whenever recommending a path forward for a newbie or someone with a less expensive system. I have a combined $2.5k sunk into my components between transport and speakers (ex-cables) and I think I'm done. Beat that price/performance ratio! System: Transport -> Nixon TD-2 DAC with added power supply -> LSA -> W4S ST-500 -> framed Maggie MMGs. The LSA replaced a modded Forte F-40 ss preamp which I think is very musical but which I now believes is grainy (not its rep). |
Jult52, glad the LSA worked for you, no audionervosa with this piece:) I think Clio and I have been recommending the LSA/Music Reference RM10 combo for world class sound for the cost of some folks speaker cables. If 35 watts is enough power, this is an awfully good example of great sound the real thoughtful engineering. You got yourself a very nice system there. |
Jult52 1) With my 1.8v DAC feeding my 2.1v input amp, I find most of my listening to be in the 12-2 o'clock range. 2) I swear there was some break-in in the bass with the LSA, lasting maybe 5 hours. 3) I am a newbie compared to the very experienced audiophiles here. I think suggesting a DAC/passive preamp/high impedance amp combo is a must whenever recommending a path forward for a newbie or someone with a less expensive system. I have a combined $2.5k sunk into my components between transport and speakers (ex-cables) and I think I'm done. Beat that price/performance ratio! Jult52 1: At 1.8k your dac does not reach the 2v Redbook CD standard, if it did then your volume on the Lightspeed Attenuator would be around 11 o'clock, but there is no problem with where it is on your system at 12-2 o'clock. 2: I don't have an answer to this, but maybe you just got used to now having bass that is tighter and goes down to 0hz (dc) instead of what you were using for a pre before. 3: Yes the Lightspeed Attenuator represents great dollar value as seen in the latest recommended components in the April issue of Stereophile, as the $25,000.00 Dartzeel NHB-18ns preamp uses a Lightspeed Attenuator volume control with a lot of switching facilities and a lot of glitz. Cheers George |
I have a combined $2.5k sunk into my components between transport and speakers (ex-cables) and I think I'm done. Beat that price/performance ratio! I accept the challenge: Allnic h1200 phono stage>LSA>Music Reference rm10, bought for total $2550 (used of course, except the LSA). I must admit that an itch has emerged for a new phono stage, but the LSA stays put--perhaps forever. |
Has anyone compared the Lightspeed Attenuator to a digital volume control on a digital source? If so, is the Lightspeed Attenuator substantially better? I know you theoretically "lose bits" with a digital volume control, but I want to know if others have experienced a noticeable upgrade with the LSA over going amp-direct from a digital source...Thanks. |
Hi Mcondon, if you can use the digital domain volume control within it's final 20% of full output, IE if it's 100 steps, then 80 or more you should not hear any bit stripping, if lower than 80 forget it your starting to go back to the days of good 14 bit of the first Marantz cdp which were pleasant, but no detail. In theory if the digital domain volume control is over 80% or close to full output it should be the only thing better in transparency and honest to the source than the Lightspeed Attenuator, because you have removed another set of interconnects, and this is always a good thing. Cheers George |
Thos pesky little people are at it again, I've been sent a few sites where they are charging $10-$50 for the Lightspeed Attenuator circuit. I have put it up free on DIY Forums, but they are out there trying to make money on someone else's I.P. So here is the circuit again FREE so you can make one yourself if you up to it, and not pay for it. Hope the moderators allow it. http://diyaudioprojects.com/Solid/DIY-Lightspeed-Passive-Attenuator/Lightspeed-Passive-Attenuator-Schematic.png Cheers George |
Thanks George, publishing your IP has been a benefit to many. Although I suppose some of "the many" don't realize how tough it is to match those LDR's. They could sell the circuit for as cheap as they can, but the overall question is can they build it well. I appreciate the efforts of the true DIY'ers that try, but frown upon those trying to cash in on your IP. |
You guys will be happy to know that the Lightspeed Attenuator has made Class B in preamps again in Stereophile Recommended Components, it got 5 star value as well because most of Class B is $3K +. An email to me said it would never get to Class A because of it's $470 price, how's that for $'s count in what placement you get. Cheers George |
Given the utterly minimalist nature of the LSA in terms on control functions, etc. you would think they would not fear the rath of their advertiser - past, present, and future to have a $470 Class component that is what is, but not a full featured preamp that "justifies" the much higher prices of other Class components. But, alas..... |
Looks like Morley muso's equipment has jumped on the Lightspeed band wagon as well claiming better sound than with normal foot operated volume pedals, pity it's mono otherwise it could have been utilised. http://www.diyaudio.com/forums/analog-line-level/187051-optical-attenuator-cheap.html#post2538367 Cheers George |
I've built the Lightspeed attenuator with the kit purchased from Uriah a couple of months ago. I'm pretty impressed. I love the utterly simple design! The sound is pretty transparent. It works pretty well with GTA tube amp. The only concern is the soundstage imaging which is not as good as before. Nevertheless it's an excellent preamp, practically free if you look at how affordable the kit is. Here's a picture of the completed unit. My Lightspeed Attenuator Kudos and congratulations to George for making Stereophile recommended component! |
Jylee The only concern is the soundstage imaging which is not as good as before.Jylee This from experience may be because it does not use the far more expensive NSL32SR2S (S=sorted)+(tighter impedance span) "quad matched" as in the production Lightspeed Attenuator. Rather it use the cheaper NSL23SR3 (non sorted)+(wilder impedance span) units and only "pair matched". And from experience even though the channel balance is fair, the i/o impedances vary quite quite a bit compared (because of the wilder impedance span)to the quad matched NSL32SR2S, and yes from listening to these the sound stage image does seem suffer at the different points of resistances. Cheers George |
I just placed my order for the LSA yesterday, after doing some experimentation first. My system consists of a PS Audio Perfect Wave DAC/Transport into an Aesthetix Calypso preamp into a VAC Phi 200 tube amp, all connected with balanced cables. My experiment consisted of going "amp direct" from the Perfect Wave DAC into the VAC Phi 200. I found that I could only turn the digital volume control up to 40 out of 100 on the Perfect Wave DAC before the volume got too loud. So I was definitely losing "bits". Still, I preferred the sound of this setup using single-ended RCA cables into the VAC. (Using balanced cables, the amp direct setup had too much upper frequency emphasis...not sure why, but reviewers say that the VAC Phi 200, even though fully balanced, sounds better single-ended than balanced.) In any case, the LSA will allow me to turn the digital volume on the DAC up to 100 and not lose any "bits". I will report back how the LSA works out once I receive it from George. |
George, I agree with your assessment. The measurement listed for each optocoupler was god, but could have been much better. Where can I get closer matched quad of NSL32SR2S? Can I get them from you? The chassis I used was sourced from a shop in asia. The price was well below $100, but the shipping cost was rather hefty. It came out a little over $100 including shipping to California. It's more expensive than the Hammond extruded aluminum chassis commonly used in DIY community, but not by much. Please contact me privately if you would like further information. |
Hi Jylee, I have been asked this too many times to remember, if I do it for one I have to do it for all. Being it's the most expensive and labour intensive part of the Lightspeed Attenuator, sorry but it's only for the production Lightspeeds. For you to do it to get a quad matched set, you would have to get 20-30 X NSL32SR2S's and match a quad set out of them at 5 different mV settings to get 4 that are equal resistances at 1 2 5 10 & 20mV each. The place you can get them from is here. http://australia.rs-online.com/web/search/searchBrowseAction.html?method=searchProducts&searchTerm=NSL32SR2S Cheers George |
Well, the warm weather has come back to Baltimore, so I took out the Atma-sphere MP3/M60 combo (the best I have heard for the Merlin VSMs) and took out the diminutive Music Reference RM10 MKII (light loaded at 27 watts) and the LSA (so small I had trouble finding it ;)). After several months of listening to one of the finest pairs of pre/amp combos at any price, I can only say this, if you speakers are 89db or higher and don't have wild impedance swings (bad for tubes) I think the MR/LSA combo, at a list price of under $2,500 for both is going to give you sound about as good as it gets. You may be tempted, as an audiophile, to insist on spending 10-20K, or more, for your electronics, and of course I have, but the truth is you don't have to. This combo, with the beauty of EL84 tubes, is going to give you sound that is just about as good as it gets, and to top it all off, they are both indestructible as far as I can tell. Do yourself a favor, stop thinking you need 100 watt tubes amps, and large complicated preamps. Now if you have already done that, than you have the money to try this combo and decide for yourself. For me it is the making a SOTA sound on a beer budget, without compromise. |
I agree Anthony, and really it comes from Roger's insistence that a passive preamp (with his amp) is the way to go, "no active will be better, but I will build you one if you insist" - he may have said "can be". Doubting Roger is not usually a good move, and with the LSA being the best passive I have tried (and 5-6 others of all ilks) and it is indeed an exceptional combo, the Sugar Ray of the audio world. |
The DAC has enough output voltage, and if the output impedance is less the 200 ohms you should be fine. My understanding is that it uses a tube output stage so I'm guessing that the output impedance is higher the 200 ohms, but you'll have to verify that. As far as the TRL OTL's I've spoken to Paul about them but we didn't talk about specs. I suspect the input impedance should be high enough, that being greater than 47k ohms. I find the sensitivity of the amp to be less of a factor. I run the LSA with my S-30 and even though the amps sensitivity is nearly 3V, the LSA does just fine. Still, you should check on that spec. Being that the LSA has just a single input you should consider the fact that if you have more than one source you're going to have to get used to swapping cables around. Doesn't bother me at all, but I suspect I'm in the vast minority on that. Then again, your TV/BR may not have the proper specs to match up with the LSA anyway. I'll let George address that one. |
Excuse my ignorance, what is meant by TV/BR? TV? but what is BR? Any source is compatible, so long as it has over 1v out and is lower than 200ohms output impedance. I have customers with tuners, Dat-tape, reel to reel, cassette and phono stages all used very successfully with the Lightspeed. There should be no reason a TV should not work either, and the earphone outlet could be used also as they are generally low output impedance to drive headphones. Cheers George |
Ha!!! Blu-ray, you guys love abbreviating things, like LSA for my Lightspeed Attenuator, every time I see LSA mentioned on the web I hope it my product being talked about but 50% of the time it's the LSA speakers. Down here in Australia we do the opposite, and lengthen things, for instance for "wife" it becomes the "trouble and strife" Anyway back to the sources compatibility, anything is, compatible dvd, BR, ect: phono stages are very worth trying from reports of the LP playing customers I have as phono stages benefit greatly by having a Lightspeed controlling the volume, be careful though some old tube phono stages are too high in output impedance, but then two of the customers have a tube stage that's 2kohm (2000ohm) output impedance and they said to me it's the best they've ever heard their vinyl played, and have ditched their mega dollar preamps. Cheers George |
Channel to channel matching using quad matched sets as I do, gives the obvious left/right channel balance (centralized sound image & stagging), and more a more stable i/o impedance. All the other copiers of the Lightspeed Attenuator on the market, do 2x matched pairs only, which is still very hard to do, some are not even doing matched pairs but series resistance and only one matched pair. Doing matched quads is exponentially more difficult than doing 2x match pairs, but the difference in sound quality and sound stagging can be heard, when A/B'd against each other. I go for plus/minus 1-2 db and then calibrate for the majority of the usable volume range. Then all matched quads are potted in hard wax to keep them as temperature stable as each other, so drift is keep to an absolute minimum. Then a final calibration done again before a 24hr paying time, then checked once again before being shipping out. Cheers George |
The ratio impedance between the series ldr to the shunt ldr is what causes the level difference, this is why it's called a voltage divider, but one that can be varied in both planes. EG: If they are at the same impedance you have half volume coming through from the source. As for the 2v or 4v choice, it depends on the poweramps gain and speakers efficiency, go with the one that gives you good reasonably loud listening level at mid position, but it doesn't really matter too much. With one of my very low gain amps I listen around at 3 o'clock with the others around 10 o'clock and you'll never guess which one has more dynamic headroom, yes the one that's at 3 o'clock the low gain amp, not because of the Lightspeed but because the amp has itself has less restrictive (compressive) circuitry. It does not matter where the volume is for listening, so long as all the i/o impedances are right, and you can reach your loudest level you want to hear. There is no such thing as dynamic headroom compression with the Lightspeed Attenuator volume control as it can pass anything the source gives out, unhindered. The only thing that will sound artifically dynamically better is a DBX unit (dynamic range enhancer) but we all (old school audiophiles ) know how disgusting they make the music sound. Cheers George |
Hi All, Can anyone help me in determining why, on some CDs, even with Lightspeed at full turn, I am not getting enough volume. System is Audiopax Model 88 amplifiers, Acoustic System International Tango R Speakers and an APL modified Esoteric X01 CD/SACD Player with Zu and ASI Liveline interconnects. Is there anything I can do to "help" the Lightspeed? Thanks James |
Gain of the Audiopax amp is 18dB so that is pretty low. Using my Atmasphere S-30 which is 16dB, depending on the CD, I get to about 3 o'clock or farther on the dial, but I do get more than adequate volume. Some CDs are "hotter" than others, depends what the engineer was doing in the recording/mix process. So it's not uncommon to get different volume levels by CD. What is the output voltage of your source? Being that it is modified does it deviate from the 2.5V stock output. Not sure what you can do otherwise, besides adding gain to your system. |
Hi James, I'm sure Alex mods the output stage and even the i/v stage of the Esoteric X01 when he does the mods, it is possible he has lowered the gain with his mod, also on inspection they are an opamp based i/v stage and opamp based ouput stage and it would be quite easy for Alex to give you more gain with these, just by jiggling around the feeback resistor value that are around each of the opamps. |
James, I have a few of those Keith Jarret ECM CDs too. I get to about 2 o'clock on the dial using my Music Reference RM-10. Most of the "hot" CDs I have I get to about 11 o'clock. Not an IC issue IMO. George might be on the right track regarding lowered gain on the source. Might want to ask Alex about that. |
Hi everyone, I stumbled across another lightspeed attenuator maker named Uriah Dailey whose product is called "Lighter Note Lightspeed Attenuator." 'Lighter Note' may be his company name - not sure. Here's a link: http://www.buildanamp.com/main.sc I don't know how it differs from George's Lightspeed version, but wanted to bring it to light (sorry for the pun) for those considering a lightspeed attenuator. |
