Yup, and well above the 12pf/ft of the Cardas, which is why I probably heard no difference between the 3ft and 6ft versions, and as Clio9 mentions, they are of course superduperlitz:)
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
05-31-11: GeorgelofiGeorge, is that what you really meant to say? I would not consider interconnect cable capacitance that approached 100pf/ft to be anywhere near being "low." For instance, just 6 feet of 100pf/ft cable would have a capacitive reactance at 20kHz of about 13.3K, certainly low enough to be significant in relation to the output impedance of your LSA, which is around 7K iirc. Best regards, -- Al |
Banquo363, sent you an email. Not sure why the Mogami didn't work out for you. It is one of two types of interconnects I use with the LSA, and as you know I also have the RM-10 MkII. In reality, the Blue Jeans cable should have been the problematic one. Anything over 2m is definitely pushing it with the LSA. One other note, use shielded or cables that use good noise rejection designs (ex. Litz). Seems to work better than unshielded by my own personal tests and I think George has recommended shielded cables as well. |
Hi guys, interconnect cables can be a mine field, not just with the Lightspeed Attenuator but with all forms of audio gear. Cables can form a hi frequency filters with their capacitance (pf picofarad)) when combined with the input impedance or output resistances of sources and loads, as can output/input coupling capacitors of some sources and amps, they can create a low frequency filters with the load of the next stage/s. Then there's the inductances and resistances of cables which can also form filters (hf, lf, even band pass) of some description. A good general rule I find is to have direct coupled outputs (no Caps) on sources you own, and direct coupled inputs on the poweramps you own, and to keep interconnects as short as possible (even if it means reconfiguring the system) and to get ones that have low capacitance less than 100pf per foot. Cheers George |
I'm not at all a 'cable guy'. It would please me no end if I couldn't hear significant and pleasure undermining differences between cables. FWIW, I'm just listening for musicality, whether my reference recordings draw me in more with one set of cables over another. I was very surprised to find that I could detect a difference. I don't know if it's the differences in length of the cables that I'm hearing or differences in the variances in construction. I don't have the same cables in varying lengths to test that. Incidentally, the blues jeans have low capacitance of 12.2pF/feet--that's why I bought them in the first place. I auditioned a 5 foot pair of magnet wire interconnects last weekend. Too lean; the harmonic richness in my Johnny Cash cd's were almost entirely missing. |
I must admit that difference between cables simply don't jump out at me - though I did buy Cardas GR just because it is often recommnded with my speakers (Merlin VSMs) - I do know they are about the lowest capacitance cable on the market (12pf/ft) so I suspect that helps with the LSA. I tried a 1m and 2m connection between pre and amp and it was simply much too difficult to indentify any difference - so I stopped trying. The only IC rule of thumb that seems to matter is short/low capacitance and you should be alright with most cables with good connectors. Can you hear a difference between 6ft - 3ft - 2ft - I don't think so - at least I can't. |
I've been playing around with interconnects and note that the LSA really responds to changes. I was having the LSA drive a 12 foot run of blue jeans cable into my rm10 amp. Sounded good to me...until I moved some stuff around which allowed me to put in a 3 foot cable I had. Much, much better--I'm pretty satisfied with them in fact. However, I can't leave my equipment as it is, so decided to buy a 6 foot (the shortest I can use if I leave my rack where it is) Mogami 2534 cables. Not good. The mogamis are supposed to have low capacitance, so I'm wondering what the issue is. What cables are people using with the LSA? I'm cheap, so nothing over $350. Also, have people noted the differences in sound depending on length? I can't imagine the 3 foot cable I used is better constructed than the mogamis (although they do have nice locking terminations) so I infer it must be the length that's the culprit. I'm thinking about trying the Tempo Electric silver cables. Any comments on those? Another point to note is the following. I bought a 2 foot Soundsilver cable (gold and silver) to connect my source to the LSA. I noted that it sounds much better using itthat way than using it to connect LSA to amp. I would have thought my cd player could easily drive a longer cable and the that the LSA would benefit from driving the shortest length, but that turns out not to be the case for me. Why? |
Teak does not shield against rf, it maybe a step forward in glitz, but a step backward in sound quality. One day I may do a remote and have a retrofit scheme for present Lightspeed Attenuators, but it would have to be a quality one, not those chintzy Chinese made ones that people are using that would come back and bite me in warranty claims. Cheers George |
Thank you George, it did not seem Uriah was doing doing the same thing, and set himself up to try to provide the DIY community with parts to build their own Lightspeed-inspired derivatives - which I imagine can sound quite good in the right setting. While appreciate the buffer, remote, and switching approaches that others have tried to add, I suspect you only really get the uncompromised LSA (sorry, we do that here) sounds used as you have designed it in a system with the right source and amp requirements - the rest come at a sonic cost I'm not willing to pay. But if I found a remote controlled, buffered preamp with multiple inputs, preferably RCA and Balanced that sounded as good as the LSA, I would buy it, but I have not found it yet. |
Hi Paul, I can answer a few points for you. 1: Nobody as far as I know uses the NSL32SR2S "S" donates selected versions of the NSL32SR2 which are far more uniform and far more expensive. 2: As far as I know nobody does matched quad sets, as this is exponentially harder to do than matched pairs, matched quads gives far better min volume level, a better logarithmic feel when in use, and more stable i/o impedances. 3: All the NSL's need to be potted together for balance stability, this is not mentioned at all with the others. 4: Some of the others, especially the ones from Asia are using a fixed series resistor (instead of a NSL) with only one NSL shunted to ground, this was my first MkI version and though still better than any volume potentiomer (pot) was clearly bettered with the MkII version which was a quad matched sets, all my MkI's were recalled 5 years ago and converted to MkII's because they clearly sounded better. Cheers George |
One type of passive I have not tried are the EVS and Endler types. While I get the idea behind why the LSA without contacts would be beneficial, it also seems that EVS/Endler approach might have some theoretical advantage, no worries about IC capacitance, no IC, two less IC RCA connections and I think EVS uses a single Vishay nude in the signal path. Any experience with these? Head-to-head with LSA? |
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. |
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 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. |
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 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 |
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 |
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 |
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 |
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 |
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. |
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. |
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. |
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 |
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. |
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. |
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'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! |
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 |
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..... |
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 |
