Well well we have a winner here in the crib. Will report further truth shortly.
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
Thank you George,my intent is to let people know that your volume control isn't going to do nasty things if someone uses cables that are a different length from what you suggest. I admit I was hesitant to try this configuration,but I wanted to remove all the gear from between my Acoustats,and long interconnects was the only way to do it. The results have been terrific, nothing was lost and more was gained. So, if interconnect issues and cable lengths are holding you back from trying the LSP,don't let that stop you from giving it a try in your system. I run an Esoteric cd/sacd into it with short DIY silver/copper interconnects and out to the power amps with 20 foot quasi balanced RCA DIY interconnects,the type of wire is unknown to me,made for me about 20 years ago.Nothing fancy,especially the RCA's. The LSP is not a component that requires the owner to only use a specific type of cable as some gear specify. Nothing will be damaged,treat it with the same type of wiring and respect as any other pre-amp. Now I am left with the audiophile's curse of wondering how much better it could get with some name brand 20 foot interconnect. Fortunately/unfortunately, there's not a lot of the good stuff out there to try in 20 ft lengths. |
I'm very conservative with that statement just in case the interconnect is poor quality high capacitance. I call it like it is and don't try give best possible scenarios only. Here is a simple semi technical explanation. In your case with 20ft, lets say that the cable is good quality and low capacitance, a nice low capacitance figure would be 10pf per ft, with your 20ft that is total 200pf. 200pf connected to the output of the Lightspeed Attenuator makes a high frequency filter of -3db at 114khz. No problem as you can see way higher than our best human limit of 20khz Double that 20ft of cable capacitance to 20pf per ft and the -3db is then at half the above at 57khz still no problem even 20ft of interconnects. Halve the length to 10ft and then your back to -3db at 114khz way out of the audio band. Halve the capacitance to 10pf and your at -3db at 228khz!!! bat territory Cheers George |
If anyone is a little put off because George says the LSA is sensitive to the length of interconnect I can state that my 20 ft interconnect doesn't present a problem. There is no lack of clarity, no loss of treble or bass and no loss of volume. It sounds like the 1 mtr Nordost I had been using. So if you think you need to invest in a special interconnect to get the most out of the LSA,give it a try with what you have. I don't know what George will have to say about this, but a long interconnect going out of the LSA to the amps is not a problem for me. |
You could for comparison against the wall wart use one of those small square Duracell 9v Alkaline batteries, or even a rechargable one, it will probably last for 24hrs. Just wire up a 2.1mm dc plug to it (but please make sure + positive goes to the centre of the plug) Anywhere between 9v-18v dc is fine, as inside the Lightspeed Attenuator there is a second regulated supply that regulates everything that comes into the dc socket down to 5vdc. Cheers George |
Bought mine at Sears: http://www.sears.com/diehard-gold-portable-power-950-with-jumpstarter-dc/p-02871987000P They have less expensive ones too. I bought this one because it powers my LSA and phono stage. You need an adapter cable but they cost around $5. Lasts for weeks without a charge. |
I just saw in your previous posts that the capacitance you have is so small on both cables it does not even factor in which goes after the Lightspeed. As the Blue Jeans at 2ft you have at 13pf per foot will be -3db at 874khz!!! And the Bryston cable you have at 3ft at 21pf per ft will be -3db at 541khz!!! As you can see it will not matter as far as the -3db roll off point, just what you prefer the sound of in which position. Cheers George |
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 |
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 |
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 |
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 |
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. |
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 |
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. |
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 |
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 |
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. |
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? |
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. |
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! |
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 |
@ 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!! |
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 |
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! |
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 |