@ clio09, Thankyou, you are a gentleman!,You also proved to be a great asset here for me, I will take a look at the threads you posted here,again, Thankyou so much!
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
@ clio09, I have not told you, my amp only has balanced and Krell cast inputs,no rca single ended inputs!, can George make a lightspeed with balanced connections?,The praise here on this product is worth while to buy and try!, To use it I have to have balanced connections, I see this thread started in 2010, and George might now 2013 have available balanced???,,Whats your advise?,, cheers! |
The LSA is not available in balanced configuration. George has stated several times that in his testing a balanced design was not reliable. As Photonman advised just get an RCA to XLR cable, but keep it short, 1.5m at the most and ensure the cable has low capacitance. FWIW I have a Warpspeed optocoupler passive preamp that uses LDR technology. It is balanced but is a more complex design than the LSA. In comparison I found both to provide satisfying results, but overall felt the LSA was smoother and cleaner. |
I have tried very very hard to make a Lightspeed MkII balanced and reliable to stay in calibration even with electronic genius's trying to help out, but without some extra electronics (like sampling impedance values sort of feedback) it does have a negative effect on the sound quality, so it is not possible, and it would of put the price through the roof. My old MkI Lightspeed design is possible to make balanced though, but it does not sound as good as the MkII. So your damed if you do and damed if you don't. Cheers George |
Not really damned. If you try to satisfy every condition, you will be in an endless loop of frustration. You have to take what works and just keep improving upon it, if possible. Many times marketing dictates product but it sounds like you do not have those pressures. The Georgelofi R and D dept is untethered and answers to nobody but you! |
What I meant is that I would not sacrifice sound quality by going back to the MkI Lightspeed configuration and having to charge more for it because it's balanced. I don't think anyone would expect that, let alone purchase it. Single ended sounds better if the interconects are kept at a reasonable lenght because of less electronics in the output of the source and input of the amps. If say 10mts or more interconnect is needed then balanced can start to sound better, but the Lightspeed is passive and it cannot drive over 10mts anyway. So we're back to square one again. Cheers George |
@ Georgelofi, Hi, This is a nice supprise!, You are the owner and Designer of the lightspeed Attenuator?, Clio09 was talking about interconnects low capacitance,, I have the Taralabs zero Gold Interconnect,To my knowledge, This cable has one of the lowest capacitance rattings in the industry!, please look at the specification sheet thats available on the Taralabs internet site, then, If you would, please give me your opinion,this interconnect cost so much money, the only option I can think of to be able to use the Lightspeed mk2 is to buy gold plated xlr to rca adapters!,reterminating this i/c is not feasable!, It would cost more to do that than the entire lightspeed mk2 cost???, my interconnect is one meter long too!, by useing xlr to rca adapters,I suppose I would loose a little performance of the cable, maybe 10%???., Is this unit you have here solid state?,and where does the soundstage set?,a few feet in front of the speakers, in between the speakers, or front and center a roll on the soundstage,what roll of seating would you describe the soundstage to be at, a,d,g???,Is the unit warm sounding,analitical on the treble,big sounding soundstage, small soundstage???,you get the picture, I would like you to be honest and describe the sound attributes of the lightspeed mk2.,I have been thru 3 digital players in 14 months, only one player sounded fantastic!, but the unit was bleading d/c from the tubes into my Krell 700cx amp, and that caused it to shutdown to standby, I had to get a refund on that new player, and the second one sounded like crap period!, I sold that one, then the third one that I do still have sounds fairly good, but the soundstage is to forward for my liking running direct to amp!,I may can resonance tune the forward sound out of it??,I have not obtained the cones of my choice yet that will actually work for tunning.,The digital unit I have uses 6h30 tubes that I really do not like!,The 12ax7 tubes have a better sound stage to me, that was in my first digital player that bleed d/c, I hated to part with the unit,I had too!,, Thankyou!,All of you chime in if you would,Thankyou to all you gentleman here, you guys are very considerate here!, cheers! |
Wow!! Your guna make me work for it, I'll try my best, in point form. 1: For 1mt anything below 100pf per foot is fine 2: Yes a number of my customers use quality xlr to rca adapters 3: Not much lost with quality adapters from what they say, the gains out weigh the the minuses big time 4: The signal only passes through one special passive fixed resistor that can change it's resistance (re: volume) according to the amount of light shone on it. but the light is control by solid state components. 5: The Lightspeed Attenuator is true to the source, it adds nothing and detracts nothing, it is the most transparent/dynamic way of controlling the volume of the source to the power amp/s. The only way that can be more so is to plug the source directly into your amp, but then you have the problem of no volume control. 6: There is no gain it is unity gain. Cheers George |
Get the Lightspeed, get the adapters, and be done with it. Given what you probably paid for those cables the investment here is minimal and the reward factor is very high. I bought a pair of adapters from a pro music store for another set up I have and use them with my second LSA unit. Works just fine. In my system the sound stage varies by recording. Most of the time it is set back, but that also has to do with how I set up my speakers as well. I have never heard a Lightspeed make a system forward sounding. Only way for you to know for sure what it will do in your system is to try it. |
@ Georgelofi, I am sorry, I did not mean for you to work for it!, I have been thru so much heart ache over audio the last 13 months!, regardless of cost of eany unit, I am tired!, It seems like nothing is what its said to be!, I hope you understand my point of veiw here,Thankyou for all the post from you, I will most likly buy from you,I have to waite till my amp comes back from Krell, I have to pay them first, then I will get in touch with you, Do not worry, you got the sale, Its just I have to give Krell 2 or 3 thousand dollars for what they are doing to my amp!BTW, My Ayon 2s is running directly to my amp!, It has a high quality digital volume control!, Like I said, A r-core transformer for each channel after the signal leaves the out-put tubes, and the third R-core transformer is for the digital domain, Thankyou, cheers! |
@ Georgelofi, Hi, believe it or not, I have used the Ayon 2s volume control at the level you are speaking of plenty of times!, It just dont have the gain for me to get the power out of my amp that I would like to have, I would say, half the power of the amp is available, no matter the max volume I set!, I have the Krell fpb 700 cx amp, I have 6 oms speakers that ride mostly at 4 1/2 oms while playing music, still, I know what high power sounds like, since I was a life long musician!, and the speakers are 91 db sensativity!, I do not like most pre-amps out there because they add a veil over the music at hand, and they always add their sound signature to the sound as well!, then theres the cost of mutiple cables, which btw, my i/c retails for $14,950.00 a meter!, one of these is what I like to stick with considering the cost here!, I still want to buy your unit, I can always use it somewhere on the other systems I am building over the next few years, by having your unit already is a plus with doing this!,, cheers! |
You will not gain anything by putting the Lightspeed into your system and I would'nt sell you one until this is sorted out. As your Krell FPB700CX has balanced inputs and is 100kohm with 3.58v sensitivity, that is, it takes 3.58v in, to take it to full output just before clipping. Your Ayon CD2s has balanced output of 300ohm with up to 5v out at full level. So you can see your Ayon at full volume output has enough output to take your Krell beyond it's full output which will damage it, you have either done this and is the cause of your Krell's damage, or something else is misconscrewed. Cheers George |
Read the above carfully before reading this. You have a switch on the back next to the output rca's and xlr's that can set the full output level at either 2.5v or 5v, I believe you have it at 2.5v from what you've been telling us. Quote from a review:Besides the outputs there are also four switches. One selects the absolute phase – 0/180°, the second one controls the overall gain – maximum output voltage of 2.5V or 5V, the third one selects the analog output we use, XLR or RCA. End Quote. Cheers George |
Hi Geogelofi, You are correct, I only use the ayon 2s player on 2.5 volts, that way I will never clip the Krell balanced input!, As far as the amp goes, I have never, ever heard this amp clip!, Yes, I do have the Ayon set on xlr setting, o degrees on the phase setting, I have played with all the settings, To my amazement, they work to very good effect!, George, The Krell was damaged when I first moved into this house I am renting 13 months ago,The receptical had 220 on it, It blew my amp up!, I sent it back to the dealer that sold me the unit used, As good as their technicians were, The compexity of a $14,000.00 amp new was beyound their experience!, I had problems with the amps bias on the left channel, It got worse as time went by, to the point that the amp was getting so hot on the left channel, that it would shut its self to stand-by!, so, my lesson learned here is to never let any body work on a Krell amp that is this sophisticated as this Krell 700cx is!, the dealer was not a Krell dealer at all!, I know of only two places here in the u.s.a. that can work on this amp to great effect is the krell factory, and the company called, the service department home, steve is the owner of the service department home, He was the service manager there at krell for 20 years before he started his own company in 2009, he is also a certified service bussiness for Ayon audio!, He told me on the phone that the Ayon 2s is really a hybred player, since the signal leaves the out-put tubes and then goes to R-core transformers that is on each channel that their is no way ever that the Ayon 2s would propose a problem for the krell 700cx running direct to amp, the transformers is the buffers for eany and all d/c that may or may not come from the tubes!, so no, the Ayon 2s was never the problem!, the problem of the krell 700cx was prior to me buying the ayon player!, the dealer who attemted to fix the unit basically band-aided the amp up to finish the sell to me!, I cannot complain alot here, they attempted to fix it for free!, At the end of the day, they had no bussiness tring to fix the amp!, they should of sent it to Krell as I did!, and since the amp is there at Krell, I am requesting for the amp to be totally renewed rather it needed it or not, that way, there will be no worrys in the next 25 years!,, cheers! |
You have no gain worries now then, just flick the gain switch on the back of the Ayon to 5v go direct into the Krell from it and you will have the most transparent/dynamic sound you can get this way, with a bit of gain to spare. If you find yourself using the Ayon's digital volume too far below 1/3 of full up, then you can order a Lightspeed Attenuator, turn the Ayon full up and have the second most transparent/dynamic sound you can get. Wished you would of told us all about the Ayons gain switch and that you had it on 2.5v instead of 5v would have saved a lot of research and guess work. Cheers George |
@ Georgelofi, Hi, The Ayon 2s sounds better on the 2.5 volt setting for some odd unexplained reason!, Like I said, I have played around with the toggle switches on the back of the player for days on in!,I also do not believe turning my system up to loud volumes on the 5 volt setting is very smart to do, considering the balanced input on the Krell is 3.3 volts or so!, This will not do nothing to the amp it can not take, my speakers, I wish not to damage those!, A 3 1/2 volt didgital player would be perfect!, LOL!,,, I do appreciate your time to talk to me here, It is very special when a componet designer takes time like this out of their busy life!,, Gratitudes to you!! |
Audiolabyrinth hi. All the gain 2.5v/5v switch is doing is changing the feedback resistor on the output buffer to another value to give 5v instead of 2.5 on the same output buffer. As far as being concerned that you have 5v out feeding into 3.5v in, this is quite acceptable, as if you had an active preamp in the mix you would have far more than that, as some are capable of giving out up to 20v or more out. So as you can see it is not out of the ordinary to have more out than what's can go in, just means you have a bit of headroom, just be judicious with the volume control. And like I said if when on the 5v setting you are below 2/3 of full volume then "Bit Stripping" can become an issue. Then you can get a Lightspeed have the 5v full up and the Lightspeed will be at or around mid 12o'clock position for normal listening with more available if needed. Or you can leave the Lightspeed at say 2o'clock and be able to use the remote volume on the Ayon to raise and lower the volume within the top 1/3 of full up, this way you will not be "Bit Stripping" Cheers George |
Thankyou Georgelofi, I know what you mean now, you are saying if I use The Ayon 2s on 5 volts out-put, and use the volume control, I would never turn it up to 5 volts, most likly the amp would be driven to full signal when the volume pushes the signal to 3.5 volts!, most likly 1 o'clock on the volume control?,, cheers! |
Just received mine and have been listening for two nights now and loving every minute of it. This little box really makes me think that I will never again need to spend bank on a pre, and as such my $3k Bryston is now sitting under my bed collecting dust and soon to be on the for sale block. Worst case scenario, the Bryston has nothing sonically over the LSA except source switching, which I do not need. The LSA is much more transparent in my system as I am hearing instruments and voices that I never knew existed in some passages, very revealing and detailed. But the first thing I did after hooking up the LSA, was to turn on my system and with no source playing I put my ear to my tweeters and with a big smile on my face, I heard absolutely NOTHING, no "ocean" white noise that I heard with my Bryston with volume at zero position. I am guessing that is a good thing but I am only an amateur at this audiophile stuff. I hate to speak in cliches, but I am really enjoying rediscovering my cd collection. But Of course, each particular recording has a different effect from the LSA. Particularly, live and unplugged music sounds more live and bad recordings sound more bad, a side effect. So your source component is now in the spotlight as to the quality of the signal reaching the amp. Now I am rethinking whether I should upgrade my source, cdp or go digital. Isn't it ironic says Alanis. I am using a 3 ft set of Bryston IC's (Canare and Neutrik) which are 21 pf/ft into the LSA and a 2 ft set of Blue Jean IC's which are 13 pf/ft out of the LSA to amp. Another nice side effect, I have one less 17" component box and its outboard power supply, less cables and wires and my rack actually looks organized and clean. So to summarize, a great sonic value and a truly novel product from a pretty cool guy to do business with from 7.5K miles away. I am very happy with this purchase and by far my best and most dramatic change to my system. |
George, I purchased that amp I was thinking about. I tried going amp-direct and controlling volume via PureMusic. The new amp's input impedance is 51K. Due to the amp's .75V sensitivity and 35db gain, most of my listening was 40% or less on PureMusic's volume bar. This resulted in a "swooshing" hiss coming from the speakers which is clearly audible from my listening seat 9 feet away and obviously unacceptable. My previous amp was an integrated so now I need a preamp which brings me back to you. As I said before, I'm a former LSA owner and sold it when I went to the integrated. I've been looking around for low capacitance rca's on the cheap (for now), to run from the LSA to my amp. I've narrowed it down to Mogami, Blue Jeans, and something else which escapes me now. You said you use Mogami. May I ask which? Studio Reference (or something like that). Also, do you know the capacitance of your Mogamis? |
I recommended Mogami which is what I use. I bought mine here from: http://app.audiogon.com/listings/interconnects-mogami-rca-1-meter-studio-standard-interconnect-2013-06-27-cables-80015. You could also try some pro gear stores. Mogami Studio Gold Neglex Quad would be one of the brands to look for. |
Devilboy, Photonman seems to have found so nice low capacitance ones, Quote "I am using a 3 ft set of Bryston IC's (Canare and Neutrik) which are 21 pf/ft into the LSA and a 2 ft set of Blue Jean IC's which are 13 pf/ft out of the LSA to amp." These are very low, I myself have not used Mogami so I can't comment on them, but if they are below <100pf per ft they should be fine, any cable manufacturer worth his salt should know this spec, and they should be made to advertise it in their specs on the packaging. Cheers George |
This can be done Nguyen, as it is how I run it, bi-amped, both amps are 100kohm input impedance, Lightspeed sees half, 50kohm, same difference. The thing to look at is the combined input impedance of your main amp and the subwoofer amp. If your main amp is say 100kohm and your subwoofer amp is 100kohm then the Lightspeed will see 50kohm again this is fine. But if your main amp is 100kohm again and your subwoofer amp is 20kohm then the Lightspeed sees 16.6kohm not so good. Cheers George |
I have had my LSA for two weeks now and I have to say this is one of my best hifi purchases in all respects. Definite sonic value. It is just as transparent as my previous more expensive active pre but with less noise so my active is currently for sale. This device has changed my attitude toward equipment purchases and shows that a little experimentation can yield pleasant surprises. The LSA is the stripped down race car or race sail boat of stereo equipment. A great novel product and worth an audition in any system. |
As for use with battery, I recommend the use of 12vdc Lithium Li_ion rechargeables, these will give a couple of week use before needing a recharge. One important question you have to ask the seller is that the plug is 2.1mm and very important that the centre of the plug is + positive. http://www.ebay.com/sch/i.html?_odkw=12v+li-ion+rechargeable&_osacat=0&_from=R40&_trksid=p2045573.m570.l1311.R1.TR2.TRC0.A0&_nkw=12v+li-ion+rechargeable+battery+pack&_sacat=0 Cheers George |
The LSA adds nothing to the mix. It will be purer and smother than the Placette if the LSA matches up with your source and amp. Minimum 2V output and less than a few hundred ohms output impedance from your source. Minimum 47k ohm input impedance and a highly sensitive amp. Low capacitance cables kept short. |
You want to keep your total length cable capacitance under 300pF, which most are anyway. Cable is usually spec'ed by how many pF per foot. So if you have a 3ft/1mt length, you want the cable to be spec'ed at 100pF per foot or less. And most are anyway, except for the rubbish out there. If the manufacture does the right thing it should be in the specs written on the box, if not he should know it, if he doesn't don't buy it as he has no idea what constitutes good cable design. Cheers George |
Cable capacitance will not influence the overhaul volume level, but it will effect the high frequency -3db roll of point. eg: If you have 1mt interconnects from the Lightspeed to the amp that are 100pf, the -3db is at 227khz If the the 1mt interconnects are 300pf the -3db is then at 76khz. Your Chordette had more gain (output level) than what you were previously using to change the normal volume level on the Lightspeed from 11 o'clock to 10 o'clock Cheers George |
I have been hearing for years CD source directly conected to QUAD II (15 wts valve amplifiers) and refusing any preamplifier between, therefore I had not any distortions but also not any control on volume. I have not perceived any change or coloration on the sound introducing the Highspeed attenuator between. So the question is not if highspeed is better than other preamps, the fact is that it seems that does not exits in the system. So, I have not improve farther the old almost optimal configuration but I have gain to be able to enyoy music without neighnours problems |
Hi Devilboy, glad your enjoying the Lightspeed with your setup. There is no problem with the 51k Z of your amp. As we have done extensive A/B listenings tests on a very high rez system with amp input z loads from 300k right down to 33k, and only then did 2 of the 40 Audiophile listeners think they detected a very slight change when we got to 33k. Just use good qualtiy interconnects from the Lightspeed to the amp/s at 2mt or less. Cheers George |