Hi Bill- Glad to hear that the surgery on your back and your system both went well. As long as it sounds good it is good! And with your back feeling better, well, I'd say you have made some very good decisions. Best wishes for a fast, full recovery!
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
Sorry no, we have done it a few times, but without the electronic type/s of feedback that other single ended Lightspeed clones use, they will not stay in calibration over a long period of time, as the matching of the 8 x led/ldr's for balanced output is exponentially more critical than just quad matching for normal single ended. We have found with a/b listening tests with numerous audiophiles, that these types of electronic matching feedbacks no matter which ones we designed, were detrimental to the sound quality of just doing the proper quad matching without feedback, even though it takes much time, labour and expense to do. Forced matching seemed to have thinner bass and more etched highs, with a lack of body to the mids, when compared to the production normal Lighspeed Attenuator. Cheers George |
I have been living with my LSA for a couple of months now. It was bought to help improve the dynamics of my system. It has worked better than I hoped for. Not only have the transients improved greatly but the unexpected gain in fine detail and accuracy of the sound placement is indeed a pleasant surprise. My system has been built up over a period of 20+ years, with the intention of getting the absolute best sound I can, while avoiding the trap of the law of diminishing returns, which is so common in hi-fi. This approach has resulted in an unconventional setup that sounds far better than the sum of components would suggest. It consists of:- Sony BDP-s580 blue ray---Musical Fidelity M1 DAC----LSA---Elliot Sound Products 4th order active crossover---Rotel RB 930AX for highs, Rotel RB991's for mids and lows---B&W matrix 801 s2's now running full active. All interconnects are standard Monster as is the speaker cabling, which has a double run for the bass to reduce voltage drop on large transients. The speakers sit on custom made lead filled stainless steel stands. The LSA has been the last link added, with the $500 or so giving far more improvement than the price would suggest. |
Hello, As I confirm with Marqmike, I will give more impression. I am still using LSA and very happy with LSA. After mod with pure silver wire and pure silver WBT RCA plug, the LSA provides very delicate micro nuance, better contrast of micro and macro dynamics, better transient and articulate bass. The treble is sparkling. The only concern is that you have to make sure that the electricity feed LSA is strong enough when LSA is run by battery power. If yours system sound is weak in dynamics, please check battery power first that it is strong or not. When battery power is weak, it makes your system sound no dynamics. However now I plan to acquire Coincident Line Statement preamp. Because my system is not loud enough when music recorded with low gain is played. My system need more gain. It is not fault of LSA. Because the sound is not loud enough also when I connect front DAC directly to amp. I will give my review between Coincident Line Statement preamp verus LSA when I got Coincident Line Statement Pre-amp. |
We've found that a buffer for the Lightspeed Attenuator is only needed if your amp is less than <33kohm input impedance or your source has a tube output stage with high 1kohm or more output impedance. If your poweramp has an input impedance less than 33kohm, then this is the best solid state buffer we've heard so far with the Lightspeed. You do have to diy a little with a simple 15-0-15 power supply, case and rca's. But it's a killer fet input, bi-polar output buffer at a stupid cheap price of $20. http://www.ebay.com/itm/171436195085?ru=http%3A%2F%2Fwww.ebay.com%2Fsch%2Fi.html%3F_from%3DR40%26_sacat%3D0%26_nkw%3D171436195085%26_rdc%3D1 Cheers George |
I purchased the following power supply based on George's suggestion in this thread, TeraDak TeraLink X1/X2 DC8.5V 1A + USB DC5V port Linear Power Supply Well I think this little power supply is a must buy for the LS. I could not be more pleased with the results. I have the linear wall wart as well as a cheap battery supply and this TeraDak is far better in my rig. Enjoying the music and just wanted to pass this on. |
Hi Grannyring, good to see your still loving the Lightspeed Attenuator. It would be nice to get a "sound" difference comparison between the standard wall wart v battery v Teradak power supply. As my a/b's with a group of golden ears showed differences when they knew which power supply was being used. But were also inconclusive when asked in blind a/b tests with the same group, then they said the differences were too close to call. Here is something very interesting that can explain why many say what they say about the Lightspeed Attenuator's superior transparency compare to volume control potentiometers used in most all commercial preamps, active or passive. http://www.diyaudio.com/forums/analog-line-level/80194-lightspeed-attenuator-new-passive-preamp-273.html#post4394156 Cheers George |
Well for me the differences were easy to pick up in my particular set up. Remember, my LSA components were placed inside my dac thus turning my dac into a dac with volume control. This eliminated the need for a set of ICs and RCA connectors. I also used some very good silver/gold solid core wire in cotton from Jupiter Condenser to wire the LSA board inside my dac. I prefer the battery over the wall wart in my system finding it sounded more relaxed and engaging. Just wanted to listen more with the battery. The difference here was slight and some may like the linear wall wart better because it did seem a tad, just tad, more dynamic and upfront. However the TeraDak supply simply put a big smile on my face immediately. It delivers the best of both the battery and linear wall wart and then some! I immediately heard more powerful and impactful bass. This was evident the moment the first song began playing. In addition, the music in general was more dynamic and alive. One final area of improvement that I found most noticeable was a blacker background with the instruments emerging with more realism, resolution, and sense of space and real estate between instruments. This was quite surprising to me and very fun to listen to. I really did not expect this result. I use two amplifiers and both revealed the same improvement. An 845 DHT tube SET amp and a Lector VM200 hybrid amp that is direct coupled. Both work great with my set up and the LSA . |
Yeah a few now have really liked the TeraDak power supply, good value for what you get $44!!!!, just the chassis would cost me that. http://www.ab-system.hk/index.php?route=product/product&product_id=64 Good to see someone else likes DHT SE transmission tube amps, I managed to get the circuit for these, and built my own 805 mono blocks (40kg each) a few years ago just for mids and highs on my esl's http://www.wavac-audio.jp/md805m_e.shtml Cheers George |
I should point out my Teradak was set to 8.5vdc, but it is simple to open up the unit and adjust to 9vdc etc.....using the blue color potentiometer. I also found improvement plugging the Teradak into my line conditioner. Lastly, I built my own cable from the LSA to the TeraDak using Western Electric 16 gauge NOS wire. That also made a nice little improvement. Loving it! |
PS: Grannyring/Marqmike If the Teradak was only at 8.5v that is no problem, as the Lightspeed Attenuator has it's own secondary 5vdc regulated supply inside, which everything runs off, and it can accept from around 7vdc to 18vdc from the external supply (Teradak) So in effect it is double regulated using the Teradak as the source DC power. Cheers George |
Hi, I want to update my Light Speed Attenuator passive pre-amp. It is replaced by Coincident statement Line stage active pre-amp(CSLS) (Transformer Volume Attenuator with DHT 101D tube gain stage.) The reason to replace is that low gain album record can be played not loud enough. The result of CSLS replacing LSA is that Pro: 1) Excellent Authority and Dynamics. It is like you change car from 1,600 cc to 3,000 cc turbo charge. Absolutely dynamics and in different world to LSA. It means that dynamic authority gains as same level as any Solid state amp. It makes you feel excite and PRaT. It can play loud peak as 101 dB of any album record (high or low gain). Previously with LSA, it plays as maximum loud of peak 99 dB of high gain record album and peak 87 dB of low gain record album. Con: 1) All nuances and micro details gone or disappear or high definition sound is gone. LSA or direct connect between source and amp provides or keep all nuances and micro details (high definition sound) which makes you feel realism of LIVE music band playing in your room, very emotional music. Now it is dilemma for me to choose between Excellent Authority Dynamics of CSLS or Nuance and high definition sound of LSA. For me, I think that CSLS pre-amp acts as drive stage of source (extension driver stage of source) to enhancing amp to get maximum authority dynamic in bass of speakers. The more gain in IN PUT of Amp. the easier of Amp to drive speakers. But circuit of pre-amp causes signal loss in certain ways, for this case, the nuances and micro details is lost in CSLS. LSA acts as volume attenuator of Amp. In my case, it is like direct connecting between source and amp so that all signal is kept very well, minimum lost. However if the driver stage of source (Audio Note DAC 3.1) can not provide sufficient gain to AMP (Decware Zen Mystery Amp) then the system is lost in some authority and dynamic in bass. I will modded CSLS by replacing signal cable wire both in put and out put cable wire to be Deulund Hook up wire 2 version 2 (Pure Ribbon Cable wire)in order to gain nuances and micro details of signal back. Because I observe that signal cable wire used in CSLS is very small normal wire. I will report back after modded CSLS again. |
Mods can cause more problems in other areas. The Decaware amp is 100kohm input impedance and it's input sensitivity it only needs 2v for it to give full output. The Audio Note DAC 3.1 has in standard form 3v output, as you can see this is more than enough. I believe in an email you sent me that the dac or amp was getting modded? If so you have lost either gain from the dac's original 3v output, or input sensitivity is now too high (2v to full output originally) on the amp. After these mods. This is the problem your having with low volume and probably the bass. If you get these mods rectified to get the gain or sensitivity back, all will be great with plenty of level and bass and you'll keep all the transparency and the micro detail as well. Cheers George |
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Array1138 I purchased the Aum passive also. The last unit the builder made before getting out. I love the sound as it sounds very much like the Lightspeed, but has remote volume, balance, and other options. It also has two outputs. I loved the Lightspeed in my current system, but really wanted remote. The unit is much more expensive than the Lightspeed so I really paid for features not sound quality improvement. |
George, Thanks for your clarify. It is not false of LSA in authority in bass and dynamic. Before I mod my ZMA amp, I connect my ZMA amp directly with Accuphase DP77 SACD/CD player. The loudness and dynamics is the same as my current set up playing with LSA. The nuances and micro details are gained after LSA is modded by 1)Changing internal signal wire to be Deulund hook up 2. 2)RCA female jack to be replaced by WBT pure silver female jack. This is the reason why I have to mod CSL pre-amp with Deulund hook up wire 2 in signal cable wire and WBT pure silver female jack and check the result in sound quality again. I still encourage that LSA internal signal wire must be replaced by high quality wire like pure silver Deulund hook up wire 2 and WBT pure silver female jack. This mod provides nuances and micro details like changing HDTV to be 4K HDTV or UHDTV. |
No problems that's fine if owners wish to mod them, with exotic wires and WBT RCA's, warranty of course is voided. The wires I use are 99.9% oxygen free solid core copper, which to my ear are neutral, and the gold chassis RCA's I use are made in Asia and of good quality. But I need to keep them at a competitive price ($490aud shipped), which equates to $338usd shipped to the USA. As our Australian dollar is only worth 69cents US dollar at the moment. If I used what you have done and also put it into a more glitzy chassis, I would have to at least quadruple the price. And that's before a remote control and receiver is even thought of. Cheers George |
But I need to keep them at a competitive price ($490aud shipped), which equates to $338usd shipped to the USA. Curious, I went and looked up what I paid for mine (I'm in the US): $450. That was 5 years ago almost to the day. At $338 (shipped!), it's incredible not only that the LSA is significantly less now than it was 5 years ago, but that it remains woefully undervalued. Good grief, just about everything in my system costs more than that-but after five years, not one piece of equipment (excepting perhaps my beloved Victor turntable) holds nearly the value to cost ratio that the LSA has for me. |
Although I read a lot of hi fi forums this is my 1st ever post and the only time I have ever really thought about posting , the reason simple the Lightspeed has simply transformed my system and I now believe I am getting the best out of the other components . The following is the mail I dropped to George after listening to the Lightspeed for only a few days ; What a super piece of kit just goes to show some real bargains still exist in the Hi Fi world and you do not always have to spend a fortune for the best quality components , without doubt the best value for money I have ever spent , thankyou. Previously I had used active preamps in my system originally a Naim 62 with Snaps power supply and then an Avondale 821 but I was never totally happy with the sound which always sounded a bit muddy and lacked in detail , so I started on my trail of trying passives of which I have had 2 over the past 12 months , latterly an Audio Synthesis Passion which was a decent improvement in terms of detail retrieval but did lack some of the dynamics I got with the Avondale .I really thought to obtain the sound I craved I would need to spend mega bucks but after much reading decided to give your Lightspeed a chance and wow from the first few minute I plugged it in it sounded just superb , I always thought the preamp was holding back my system but the increase in transparency dynamics and detail retrieval far surpassed any upgrade I have ever made in my system ! I did consider various types of passives including Transformer based preamps but so glad I made the decision to try yours ! which I very much doubt could be improved upon at any price . For the record my system comprises Marantz CD63 heavily modded , Avondale S100 power amp and ATC SCM 7 speakers with Mark Grant interconnects. George in my mind your product is the bargain of all time in Hi Fi terms and will be my last ever Preamp , once again congratulations on a great product |
Hi, I just want to report back after modded CSLS. My Coincident Statement Line Stage Pre-amp is modified by replacing signal cable wires both in put and out put cable wire to be Deulund Hook up wire 2 version 2 (Pure Ribbon Cable wire) in order to gain nuances and micro details of signal back. Because I observe that signal cable wire used in CSLS is very small normal wire. Result is that new modded CSLS combines best of both worlds now. It has both excellent high definition details of sound as passive pre-amp strength and excellent weight and authority (dynamics) as active pre-amp strength. However the cost of modded equipment (Duelund hook up wire 5 meters and 3 pairs of WBT pure silver Nex Gen RCA female plug) is USD 1,500 which is quite high also. But it is worth every penny. |
Hi George, i am listening your lightspeed attenuator now for three weeks. The first impression was not very good, but after burning in the lightspeed attenuator works better and better. I think there is a minimum burn in time of 50 hours. Now there are very transparent mids, deep bass, and fine highs. The space between instruments and voices is very good. Definately the best preamp i ever owned. My system is: Denon DP 75 with Jelco SA 750E and EMT XSD 15 in a handcrafted very heavy plinth Acoustech PH 1 phonopre Goldnote Koala Anniversary tube CD Player Valvet A 1r2 mono amplifier Dipol speaker with active dipol bass from Packhifi Berlin, the very best speakers i have ever heard. It's connected with synergistic research tesla cable. I am very satisfied, maybe there is a friend, who will buy a second attenuator from you. Best regards Joachim |
Hi Musicmuskrat23, thanks for your very kind words. As for burn in I do believe that the Cadmium Sulphide component of the LDR does take a while to "form" after it's not been powered for long periods of time. I've seen this on the scope from new, but it's only a short duration. But in HiFi as you know anything is possible. As my ESL speakers are big ML's, I've measured them with an ESL volt meter, and they are fully charged within 5- 10mins to 5kv, but I swear they sound better after an hour, at which time they are still at 5kv. Cheers George |
Hi George, Since receiving the Lightspeed attenuator last week, I've had the pleasure of using it as part of my single source wireless audio system. Just as a reminder, I'm streaming Spotify Premium audio from my laptop using Airfoil for Windows to an Apple Airport Express connected (wireless connection) to the Lightspeed attenuator, then into my amplifer. I used two different amps, a TPA3116 with an Aston power supply, and also a Luxman R114 (amp section only). The amps have an input impedance of 30k (TPA3116) and 47k (Luxman). These different impedance values present no noticeable audible sonic effect at all. The Lightspeed attentuator is the first passive volume control that adds real dynamics to the mix regardless of the listening volume. It allows for lower volume listening without losing any part of the sonic picture or dynamics. With other passives, I had to turn up the volume attempting to hear all the detail in the music. Using the Lightspeed that is not necessary. This is a new experience for me, to enjoy the music with all it's fullness and beauty while listening at lower volumes. Awesome! Regarding clarity, resolution, detail, transparency, it's all there in spades! Best I ever heard without a doubt. Even low frequency notes are resolved in a way I hadn't noticed or heard previously on familiar recordings. One other feature of the Lightspeed VC that I really like is that the control knob has plenty of adjustment to set the volume just right. In other words, unlike many active preamps, the Lightspeed increases or decreases the volume in a subtle manner, a little at a time. And, it allows the user to utilize the full travel of the volume control. The Lightspeed VC is the perfect addition to my simple single source system. At my age, and with my simple audio system, I do not foresee ever needing another volume control. Thanks, George, for providing such a wonderful audio product at an affordable price. It's amazing! |
The Lightspeed attentuator is the first passive volume control that adds real dynamics to the mix regardless of the listening volume. I've had this said many times back to me by Lightspeed Attenuator owners, and asked by them why this is so. These are my beliefs. Try to stay with me with my explanation below. In normal high or low quality volume pots, the source's easily corrupted low level signal has to travel through it. And there is a dimple point contact between the wiper and the resistive track it wipes on. This is very light point of contact on purpose so not to wear out the delicate resistive resistance track. The source's signal has to travel through this point of contact. These pots are also made from two dissimilar materials, the wiper usually being brass and the track another material. This can be the source of a "Diode Effect" And when turned up or down this effect can change the amount of "Diode Effect" and influence on the sound, the lower the listening level the higher impedance part of the track, the more "Diode Effect"?? Imagine the link below as a normal audio volume pot high or low quality. The "screw" being the source input of a pot, the "whisker" being the pots wiper, and the "rusty razor" blade being the resistive track of a pot http://www.electronicstheory.com/COURSES/projnkits/projDiode.htm As Roymail and other owners have pointed out to me, the Lightspeed doesn't loose it's sonic picture, dynamic ability, and fullness regardless of the level being listened to. To me this is because there are NO light contact points at all in a Lightspeed Attenuator, everything is hard wired and soldered. Also Dartzeel with their $25k NHB-18NS preamp maybe also must think this, as they have used the Lightspeed volume in it, they call it a "Pleasure Control" BTW: Roymail thanks for the great review! Happy listening Cheers George |
I have been a member of Audiogon for many years. I read member product recommendations, or criticisms, very carefully when I am researching information about audio products that I am considering for possible purchase. And that is how I discovered this thread. Thanks to the positive reviews posted here by 'Pubul57' and 'tradeontheweb' for the LightSpeed Attenuator, I recently purchased one directly from George Stantscheff in Australia. It was delivered to my door in the US on time and in perfect condition. I designed and built my own simple 2-way Open Baffle set-up, which is bi-amped, consisting of a pair of Lowther PM5A Alnico/Ticonal on top played ‘full-range’ (it has a ‘secret' ingredient of Titanium added to the metallic soup of the Alnico magnet) driven by the 2-watt Yamamoto A80S 45 Single Ended Triode amplifier, and a pair of Eminence Alpha 15A’s on the bottom, passively high-passed at around 250-300 Hz (using a coiled inductor) driven by the Millenia TBI integrated Class BD 8 watt amplifier. I split the streaming signal from Spotify on my iPad mini to both amplifiers. I was using an inexpensive ‘passive’ preamplifier that I had on hand to attenuate the signal to the Yamamoto SET amplifier, which allowed me to stream the signal from the iPad mini at full volume. The little TBI amplifier already has a volume control. I was reluctant to use the iPad mini to attenuate the signal, although it does have a control for volume, because I read that a digital volume control strips-out detail. I became convinced after careful listening to my set-up that the passive preamplifier was holding back the performance of my OB’s. So I switched-out the previous inexpensive passive preamplifier and sent the signal directly from the iPad mini to both amplifiers using the volume ‘controls’ on the iPad mini and was greeted with much more detail and an obvious jump in the sense of ‘presence’ and ‘immediacy’. Thus began my search for a preamplifier that would not limit the ‘fidelity’ of the streaming musical signal but give me control with more delicate volume settings. In my past experiences with Single Ended Triode amplifiers I had experimented with several ‘passive’ and active preamplifiers, and every SET amplifier sounded more alive, more magical when I used a passive preamplifier, except for one SET which needed an active preamplifier to come fully alive. The Yamamoto already sounded wonderful and magically alive so thankfully an active preamplifier was not necessary. A ‘passive’ preamplifier, often referred to as an ‘attenuator', has no ‘active’ stage to boost the initial 2-volt signal generated from either a CD player, or as in my current set-up, streamed from the iPad mini, to the amplifier. It ‘attenuates’ downward from the peak volume of what 2-volts delivers from source. I did my usual ‘research’ which is to try to read everything one can find on the web, written by ‘professional’ reviewers like Srajan of 6-moons, and members of audio-related circles, like our community here at Audiogon, and what different products themselves suggest on their websites. As you might expect there are differing opinions about the various circuits that are being offered by manufactures world-wide. At one point I narrowed the search to two offerings, Bent Audio’s version using the Slagle’s autoformer, and George Stantscheff’s LightSpeed Attenuator. Alas, John Chapman of Bent no longer offers a ‘finished’ passive preamplifier, only parts for a DIY project. Dave Slagle offers a passive version that is expensive and aesthetically unappealing to me. I wrestled my way out of the usual paralysis that prefigures one’s audio choices by contacting 'Pubul57'. He was extraordinarily knowledgeable and helpful, and based on his feedback, I went ahead and ordered a LightSpeed Attenuator. George Stantscheff is a pleasure to work with. He is honest, knowledgable, generous and extremely helpful. It cost me $400 shipped directly to my door from Australia. His ‘Attenuator’ uses LED light transmitting optocouplers instead of metal contacts. Here is a brief explanation of this ‘revolutionary’ approach from the website, DIY Audio Projects: http://diyaudioprojects.com/Solid/DIY-Lightspeed-Passive-Attenuator/ "What makes this passive preamplifier interesting is that there are no contact points in the form of a "wiper" as in the case of a potentiometer or "switches" as may be with a discrete stepped attenuator. The key components in the Lightspeed Attenuator are Silonex NSL-32SR2 Optocouplers (PDF - 34kB). The optocoupler device is a sealed unit which consists of a high performance LED that shines on a light dependent resistor (LDR). The operating principle of the optocoupler is fairly simple. As the intensity of the LED varies, so does the internal resistance of the LDR (resistance decreases with increasing light). So in the case of the Lightspeed Attenuator, we change the volume (resistance) by changing the intensity of the LED. By using a series and shunt combination of optocouplers the attenuator can be configured to produces a constant input and output impedance, regardless of where the voltage control setting is.” George’s LightSpeed Attenuator needs an AC to DC converter to light the LED optocouplers and can stay on all of the time with the volume controls set at half, or lower, as in my case, with an estimated LED optocoupler ‘life’ of 50 years. I wish the tubes used for the Yamamoto could last 50 years! I plugged it in and waited the 15 minutes that George recommends before engaging it. What I heard immediately confirmed that the volume control on the iPad mini was stripping vital detail and ‘presence’ from the musical signal when the volume was lowered, which was necessary in order to not be blown out of my house at full volume. What I did not expect was the incredible velvety smoothness and additional sense of transparency that the LightSpeed immediately rendered to any music I played through the Yamamoto. Now I was able to use the iPad mini at full volume using the LightSpeed Attenuator to raise or lower the volume of the Yamamoto with absolutely no compromise of important detail and ambient spatial presence, no matter what volume I played the music. Also, and just as helpful, the volume of both amplifiers can be adjusted for a seamless musical presentation that is completely convincing. The fact that I can play the LightSpeed Attenuator at much lower volumes without losing the magical sense of ambient detail, immediacy and presence, that is the pure delight of the Open Baffle presentation, allows Deborah and I to listen to music late at night without fear of bothering neighbors. With the LightSpeed Attenuator, there is more of a sense of ‘air’ around voices and instruments. As it turns out the Yamamoto SET is more crystalline and transparent than was apparent before using the LightSpeed. And beyond that, what we are hearing now is a deep resonate sense of any instruments materials, like a cello’s wood and the rosin on the strings, or a flutes metal mixed with the vibrating reed, or the deep warmth and emotional complexity of the human voice. The LightSpeed Attenuator is an incredible bargain. It allows the Yamamoto 45 SET amplifier to deliver its magic with a velvety smoothness that is entirely addictive. The dual volume controls are a wonderful way to adjust each channel separately which is very helpful for recordings that are biased towards one channel. Incidentally, the controls have a precision and smoothness to the touch that one expects from very expensive audio components. That the LightSpeed Attenuator is so reasonable boggles the mind; how does George do it? I even like the simple elongated black rectangular design. It looks great next the rest of my components. Personally, I do not like remote control, volume controls. I like the 'feel' of the LightSpeed controls and the incredible precision it offers. Being able to regulate the volume with this much nuanced precision actually affects how the 'texture' and presence of different instruments are perceived; it is a pleasure to experiment with the volume controls in this way. With Warmest Friendship ~ Richard |
Nice “long” review Richard, and I wholeheartedly agree with all you said. I’ve had my Lightspeed going on ten years now, and even with many system changes can’t find any preamp, active or passive, that betters it. And George, I wonder if there’s been any tweaks since I’ve owned my Lightspeed that you’ve found, power supplies etc etc? |
I first would like to thank Richard also for that very in depth (War and Peace) review, keep up the good reviewing format, I think you may have missed your vocation in life. As for any tweaks that tradeontheweb asked that may have been done to the "MkII" Lightspeed Attenuator since it’s release, it’s still the same save for minor cosmetic changes. Though in the power supply area, "some" have found a small benefit using this power supply to power it, instead of the supplied one. It’s is very nicely made and not too expensive at $44usd, myself I have not heard it, and think it could be a bit of overkill, but in this game who knows, I know it’s 9vdc instead of my supplied 12vdc, but the Lightspeed Attenuator can run on 8vdc to 18vdc no problems. http://www.ab-system.hk/index.php?route=product/product&product_id=64 Thanks again Happy New Year Cheers George
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tradeontheweb You can also try these Li-ion rechargeable batteries, these do have something that is detectable when compared to the linear wall wart. What the difference is no one can quite put their finger on, they just say there is something different. Even Sam Tellig from Stereophile says the same when he reviewed his Lightspeed, same went for his son a guitar teacher with his. What’s really good is, as the Lightspeed consumes so little power, these rechargeable Li-Ion batteries give a good couple weeks of use before you need to recharge them. Worth a try also as they are only $10 - $20 with charger shipped. Cheers George |
Hi, this is the one I sometimes use, it's encased in black plastic and is also 6800mAh's which should see around 3 weeks of Lightspeed listening before a recharge is needed, which only takes around an hour. There is something about the sound of pure battery power with the Lightspeed you sense something is different compared to the linear powerpack, but you just can't put your finger on it. It's subtle but there, sometimes you can make the mistake of thinking your listening to battery power, when in fact it's being powered by the linear mains power pack. Let us all know the differences you hear of the three different way of powering the Lightspeed? Cheers George |
Hi all. Just a short note to let anyone who may be interested how I came to buy a Lightspeed Attenuator. I bought a Halcro MC 20 power amp which was on special from Magenta Audio in Adelaide and being a power amp, I had to find something to adjust the volume and putting out 400 watts per channel, I figured I could go passive. A Google search turned up George Stantscheff and his amazing Lightspeed Attenuator. It simplicity (and price) impressed me so I took a chance and bought one. It has turned out to be one of my better hi fi choices. I'm running a Sony SCD XA5400ES sacd player thru the Lightspeed, Halcro amp and into a pair of three way floorstanders with Audax drivers and the sound is so "pure" and clean, I feel there is nothing in between the source and the amp. Last year I started to set up a pc based music system and bought a Benchmark DAC2 HGC that I connected to the digital out of the Sony to replace the Lightspeed and it delivered the music in spades, but after a couple of hours it began to fatigue me. After a week of using the dac I took it out and replaced the Lightspeed Attenuator and restored the clean, open sound I was missing. So I think I'll not bother with the pc based music system for a while. Keep it simple!! |
My Lightspeed Attenuator now a few months on from purchase is still proving to be a superb purchase . I have been experimenting using a cheap Breeze Audio Linear power supply against the wallwart supplied with the unit , I have used this unit for the last month or so and believe it just shades the wallwart . However the unit has a led display and was originally set to 9v DC output showing 9.2v when originally connected , I have however noticed recently the display is showing what I believe is referred to as ripple and varies from 9.20 to 9.23 often changing every second or so , does anyone know if this is normal . I thought the whole purpose of a linear regulated power supply was to give a specific voltage without fluctuation and also would ripple potentially effect sound quality ? I have searched the internet but any explanation given is above my understanding . Finally battery seems to be an option has anyone had any positive results using a battery supply ? notice you use one George I am also interested in other users feedback |
Hi hammering, you echo the responses of so many owners when you said. "It simplicity (and price) impressed me so I took a chance and bought one. It has turned out to be one of my better hi fi choices." This "kiss" is the way I like to keep it, to get the source signal to the poweramp/s with the least amount of colourations. You should also give the $29 battery a try that I posted in my last post, as it is the purest way of powering the Lightspeed and will last a good 3 weeks before a recharge is needed, and please give us an A/B comparison if you get one between it and the supplied linear wall wart. |
I thank you also miller65 for your glowing response to your purchase of the Lightspeed Attenuator. As for your question: "I have however noticed recently the display is showing what I believe is referred to as ripple and varies from 9.20 to 9.23 often changing every second or so , does anyone know if this is normal." This will not effect the performance of the Lightspeed, as for two reasons, the Lightspeed itself also has an internal regulated 5vdc supply it runs on, so any slight fluctuations from your external supply will not have any effect on it’s stability, secondly the 30mV fluctuations you have on the display could be due to slight temp variations inside your Breeze Audio Linear power supply. What you should do is also get the rechargeable battery I posted 2 posts back, as it will be the purest most stable noise free way of running the Lightspeed, and give us your opinion on how you like it’s sound, as for just $28 it’s a cheap experiment, and will leave no room for doubt as well. As we all know audiophiles have doubt if there is a question mark with anything, and it can eat away at our senses sometimes. Cheers George |
I bought two LA 's from George and I would want to share with you my experience. I have in the past a numerous of preamps and my last one was a Audio Research LS 26 : having listened to the Lightspeed Attenuator I sold it. The LA is so much better. The LA may at first use sound " a little britlle " but when the impedance matched correctly it is amazing good and it beat all the preamps I had before. Between my Audio Research DAC 8 and my Pass Labs amp it is a perfect match. I am very happy with it - I can only say : try it Thank you George. |
Thanks George the temperature variation in the power supply makes sense as it is more stable in line with a stable room temperature I also intend trying with a battery in the next few weeks. As a next stage I am considering using my CD player as a transport and introducing a DAC into my system this will also enable me to include a network player at a later date. However having checked the output spec of the DAC Beresford Caiman mk11 I have a couple of questions in terms of how output impedance can effect the sound quality . The output voltage of the DAC is 2v which is in line with LSA recommendation but the output impedance is 1k ? appreciate it should be 200 ohms or less ideally . Iwill use with a very low capitance Stager silver solid i/c 0.5 metre length . Does anyone have experience of using the LSA with output impedance this high and if so what if any effect can it have on the sound / volume control . I love the transparent dynamic sound the LSA currently gives me and wonder if this potential impedance mismatch would have any adverse effect on the sound quality or use of the volume control which currently operates at 12 o clock , which is generally plenty loud enough |
Hi George, I'm thinking of an DIY LDR attenuator to replace the stock 10K Alps dual pot in a Sennheiser HEV70 energizer for HE60 electrostatic headphones. I need to step down from 25Vdc to 5V for this application. The chassis is cramped and there is little room inside for a heat sink on the down regulator. An LM2596 looks like an easy fit in terms of low heat dissipation and compactness. Do you think this would compromise sonic performance relative to a LM7805 linear regulator? My concern about the LM7805 is overheating from the 20V step down. Thanks, Dave |
