I'll think about it, sounds like fun. Now, back to our regularly scheduled program.....
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
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"I too will be getting an opportunity to hear the LSA and compare it to my TRL Dude. That should be fun. More importantly, I will involve my non-audiophile, musician wife in a blinded listening test between the two and will report on her findings rather than mine." (Agear) Agear, have you been able to do this comparison yet? looking forward to it. |
I decided to take Pubul57's lead. Using the Lightspeed Attenuator with the Music Reference RM-10 MkII. Sources are the db Audio Labs Tranquility SE DAC or the Ray Samuels Nighthawk phono stage. I don't miss having an active preamp at all. The sources have 50-60 ohm output impedance, and the amplifier has 100Kohms input impedance. I think with the right components and appropriate input and output impedances you won't miss an active preamp either. |
Wilsynet, I'm glad you gave it a try. By the way, Clio9 is also using the LSA with the RM10MKII. Not sure if this is the reason why, but one reason I felt the compulsion to try a passive was the Roger Modjeski (Music Reference)told me to use a passive, that no active could be better; though he was willing to build me a more traditional tube-buffered with or without gain. Well, you know Roger can buiild anything, and he loves selling tubes, yet this fella who knows a thing or two about audio insisted to go with a passive. Then I read Arthur Salvatore's comments on passive versus active. Well, I had to go about testing the concept and have had Placette, Goldpoint, BENT TVC and AVC, and Roger's Pot-in-a-Box - they all sounded excellent, these were not gradations of crap to great, they were all at least very good, and at the end of that path I came to the LSA which was the best of the lot IMHO and I'll say that in my system with ideal[?] impedance matches and ICs the LSA is the best passive preamp I have heard, and I suspect if your system well suited toward the passive approach the LSA will give you SOTA sound quality for $450 which is a good thing to know, especially if finance are an issue, combined with the RM10MKII I think that is just about as good as it gets IF 35 watts is enough power for your speakers, room, listening volume. |
Wilsynet, glad you were able to put together this combination. It is incredibly good for the money. I have about $1500 invested in my LSA and RM-10 MkII. That's tough to beat for SOTA sound. I've been listening to the LSA with battery power supply for a while now. I would suggest to anyone that owns one to give it a try. The parts cost is less than $75 (here in the US anyway) and it's plug and play. Also, I've been using my LSA with the Atmasphere S-30. Now I'm tempted to break out the RM-10 again. |
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I agree with the assessment, although some tube rolling could change that. Pubul57 might be able to share more on that as I believe he has done some tube swapping with the amp. I use the stock tubes as supplied by Roger and the way Srajan describes it is how I hear it. FWIW and if IIRC, Roger designed the RM-10 using Quad 57 speakers with it for his listening tests. There are some other interesting design characteristics about the amp that fly in the face of typical amp designs and how we audiophiles associate various sound qualities with them. Tvad, if you're interested in hearing the RM-10 let me know. I'm not using mine at the moment. If possible I'd like to compare the RM-10/LSA combo versus RM-10/VRE-1 combo. |
I would say the RM10 is quite neutral and fast with the LSA, as described in the 6moons review. But, use it with a 6sn7 based active preamp, and use RCA 6sn7s and you might have a "tubier" flavor, but the amp itself seems neutral, with tube bloom and soundstaging that only tubes seems to do compared with even the best SS. The RM9 with EL34s is a slightly darker flavor, but I think Roger has always designed with neutrality in ,ind and nothing overtly tubey in the CJ/Cary vain. I am always amazed by the RM10. I wonder what the mono setup wpould sound like - I suspect Roger would say the stereo version is better if you don't need the extra power (35 versus 70 watts). |
I do agree with the review. It's a well balanced amplifier, does everything well, some things very well and nothing at all poorly. It is very, very good with the LSA. Regarding speed, it's fast but not fast like the Atma-sphere S-30. On the other hand, to these ears, it has more density than the S-30. The 6moons review notes that the amp is not as good with complex music at scale, I have no such observation, although my speaker load is particularly benign and efficient. |
Wilsynet, I agree with everything you just said, and the Merlins, like the Zus are very benign loads, and efficient enough for 35 watts. I think, not always sure, that my preferred system is the all Atma-sphere rig, but the LSA with my RM10s and RM9 SEs, are might fine, can't really get myself to sell any of them. In my system, I preferred the Atma M60s and MR RM9 Special Editions to my CAT JL2s which I thought were just about as good as amps could be, certainly the CATs can handle a wider array of speaker loads than the Atma-sphere, but those RM9 SEs put out 162 watts into 8 Ohm and 200 into 4ohms, that is alot of tube power - if I could only own one amp for all seasons it would proabably be the RM9 (with my LSA). |
Light loading is supposed to make the amp more linear, with significantly less distortion, and more headroom. Yes, there will be less power (negligible in my case), but the damping factor doubles. My speakers are rated between 8 and 12 ohms, so while I've used the 8 ohm taps on the amp, I'm not sure I'm getting the same benefit of light loading as others who might be using the 4 ohm tap for their 8 ohm speakers. Perhaps using the 4 ohm taps would be better. I'll go over to Audio Circle and post the question over there. |
I've light loaded the RM10s and RM9s and prefer the 8 ohm tpa with the Merlins - in part, this must be because the VSMs are not speakers seaking more damping from the amp, so it might be very speaker dependent. There is a thread on Audio Circle like you mention. Might be an interesting question as a separate thread, that is the whole light loading approach with amps that have differrent rated taps. |
Just looked at the Merlin VMS impedance graph (Stereophile), at it shows it only drops (over a very narrow band)to a minimum of 6 ohms at around 170hz at 0 phase angle. This is an easy to drive speaker and should be driven off the 8ohm tap. Buy driving of the 4ohm tap all you achieve is loss of power from the amp, vitually no gains whatsoever. Cheers George |
That's what it sounded like to me. It seems that light loading is effective at dealing with speakers that have hard loads for tube amp and it improves the situation - with the Merlins and Audiokinesis Jazz I suspect the extra power of the 8 ohm tap is the better option. To get back to the subject, I would strongly recommend that all Music Reference RM9 and 10 owners try the LSA if they have a single source setup (actually any tube amp owner with sensitive 1v amps and 100 kohm input impedance). Is it just a coincidence that 3 of the LSA users also have a Music Reference RM10? Or is it just a match made in heaven for $2,500 MSRP? |
The extra power is certainly a consideration in easy to drive speakers. However, the other benefits of light loading should be considered as well, namely lower distortion and increased linearity and head room. If your speakers can handle the loss in power, roughly 7 or 8 watts, in exchange for the increased head room why not try it. FWIW, I was listening late last night with the speaker cables connected to the 4 ohm tap. I didn't notice any loss of slam or dynamics and I was listening at considerably lower volume. Maybe I'm mistaken but wouldn't that be an effect of increased head room? This combo is certainly very special. I wouldn't let the single input/output stop you from running it with multiple sources either. I have no problem swapping cables between digital and my three analog sources. Question for George: In comparison to my Atma-Sphere amp which is less sensitive and has less gain the RM-10 doesn't require me to use as much of the volume control. I seldom get past 12 o'clock and most CDs come in around 10 - 11 o'clock for normal listening. Any potential sonic issues one should be aware of. I would think not base on what I'm hearing but thought I'd ask anyway. |
For those interested I posted the light loading question over on Audio Circle under the Music Reference section: Music Reference RM-10 Light Loading |
11-02-10: Pubul57 >But there is no output impedance optimization based on dial position 10-12-2 o'clock - is that right? Some attentuators seem to have optimal positions in that sense.< Anywhere between minimum and 3-o'clock is good if i/o impedances are met. If it's after three o'clock for normal level listening in a system then (cdp/amp)has a gain shortage, or ridiculously inefficient speakers (80db or so). I have a friend that has JBL4350's and Array 1400's and his 80watt Transcendent OTL monoblocks just have enough power driving the 4350's full range but the bass is seriously lacking, but they do sound good on just the upper bass, mids and tops. As for the 1400 Array's they can't even drive the mids and tops on those let alone the bass as well. Cheers George |
Mine was delivered today. Transit time was 15 days to USA. George shipped within 2 weeks as promised after placing my order. It's nice to deal with someone with a HONEST and accurate estimate. No BS why estimates are constantly revised ... blab blab blab I bought it out of curiousity and also been looking for a non tube preamp for the summer that is good enough that I will enjoy. Initial impression is VERY VERY positive. |
Pubul57 - I used to have an Audio Aero Capitole MKII SE CDplayer with built in preamp connected directly to my amp. I had to sell it to buy a new transmission for the car (ugh!!) so will be using a old Sony CD player with the Lightspeed until funds will allow an Mac Mini computer to act as source that'll be connected to a Pro DAC which will feed the amp. |
RCA ICs finally arrived and here's my .02. LSA is a very good match for my system. For most of my listening, the volume control is between 8 and 9 o'clock and 11 max. My 2 sources are MW Transporter rolling 6sn7 and TRL Sony SACD player, EW Andra II speakers, TRL Samson mono amps and all ASI Liveline cables with several TRL power cables. I find the LSA very transparent and detailed where complex and poorly recorded compress passages are easily deciphered. Excellent bass, big sound stage, extended highs and surprising excellent dynamics that plaque many passives. Compare to my VAC Signature MKIIa preamp, in MY system, I find the VAC is in another league. Not 30x better but SUBSTANTIALLY better in every way. I CANNOT imagine selling it for the LSA in terms of sonics. The boundaries around images are better defined and more separation from each other. Images and sound stage are much more 3D, layered and textured (I guess the magic of the Telefunkens), there is a sparkle to the sound, better dynamics where everything sounds tighter, airier and faster ... LSA sounds soft and 2D in comparison. Probably not unexpected, I much prefer the Transporter than the TRL Sony with the LSA having some tubes in the chain. With the LSA, I prefer rolling the sweeter sounding Sylvania 6sn7GT "Bad Boy" and Shuguang BT CV181-Z with the VAC. Bottom line, LSA is an excellent preamp regardless of price. I could easily live with it as my only preamp as long as I don't play the VAC back to back :-). I was looking for a cool running SS preamp for the hot and humid summer months and the LSA will fit the bill nicely with only a little sacrifice. |
Knghifi, glad you found the LSA a good listen. There is something that a good tube preamp does that is very enjoyable indeed, and the VACs being some of the finest. I went back and forth quite a while with my Joule 150 Signature Edition (which is supberb)but for my taste, I enjoyed the LSA every bit as much, so for the price difference I could not justify keeping the Joule, given that I have the Atma-sphere combo for cooler months. The LSA/RM10 I will use in the hot and humid Baltimore summers. I guess what I'll say for now, is that the LSA/RM10 combo is a killer pre/amp combo for less than $2,500 where 35 watts is enough power. If I were an audiophile on a limited budget it would be my number one choice, and with the right speakers maybe where budget is no limit too. |
Hi guys and Knghifi, glad your enjoying the Lightspeed Attenuator, you've put it up against a very expensive ($14,000) in the Vac Signature pre, I'm over the moon it held it's head up high against to it. One question Knghifi the poweramp TRL Samson you used for the comparison, it's a solid state amp and I have looked everywhere for it's input impedance and nowhere can I find it, as the Lightspeed Attenuator likes to see 47kohms or higher for the poweramp it's feeding. If the TRL is lower than this you have still not heard the Lightspeed at it's best, and heaven forbid it may beatout the VAC Signature if it sees an amp with the input at 47kohms or higher. Does anyone know the input impedance of the TRL Samson? Cheers George |
My LSA keeps getting better with time (I've had it less than a month), so I'm withholding final judgment until later. Definitely needs warm up use time to sound its best (the second side of a record, and beyond, always sounds better than the first side played). That said, it delivers beautiful sounds right now and no way I would sell it. And, yes, George is a standup guy who is very quick to answer questions and delivers as promised. |
It would be good for someone to grab an ohm-meter and measure the input terminals (Amp off naturally). If it is bipolar transistor input you can bet you life it's going to be less than 47k. If it's fet transistor input there's a chance it's 47k, maybe higher. If there is no reading or wavering all over the place it has capacitor coupled input (yuck and double yuck) Cheers George |
Banquo363 As stated in the instructions, you can leave it powered 24/7 just leave the volume at half position when not playing music. If using battery supply this is not possible, but still you can plug in the wall wart and leave it on 24/7 and you can change over to the battery even while playing music just pull out the wall wart plug and insert the battery plug quickly, no bangs or crashes. Cheers George |
Banquo, Your experience mirrors mine. If you look back in this thread, I originally posted that my Supratek bettered the LSA in my system during my initial trial period, which as I recall, was a rather short audition. I later gave the LSA another chance after reading how many mega-dollar preamps had fallen to the LSA. I re-inserted the LSA into my system and left it there. Sure enough, I finally had to admit the LSA bettered my Supratek (which, by the way had been considerably improved with a DACT attenuator, V-Caps, better wiring, WE 350Bs, etc.) In truth, the LSA was only very, very slightly better than my Supratek, but wow it is so much more user friendly without the hassle of tubes. |
Since I asked the question in terms of absolutes (Best)I repeat what I said early on - it is silly to speak of any piece of gear that way, and there are obviously many (some?) world-class line stages out there some which you or may not prefer to the LSA - why there isn't only one product on the market afterall. I now wish I had names this, LSA, Best Sound per $$$ Ever? - I think there would be much debate about that. The only problem is I don't think it is fair to make reference to it simply in terms of value for $$$, it does it a disservice to couch it that way - it is simply a very, very fine linestage that will suprisingly compete, and for some, surpass, many highly regarded linestages regardless of cost. In other words, worth auditioning no matter what you circumstances, and a must audition if you have limeted funds. |
George, When I wrote "warm up use time" I meant actually used to play music. My LSA is already always plugged in and at half position (per instructions), but I've noticed that irrespective of that, my vinyl always sounds better on the second side (and beyond). I've tested this by playing the first side over again--always sounds better the second time. It's not my phonostage (which is always on) or my amp which I switch on, without fail, at least an hour before use. To be clear, this is not a complaint but rather just an observation. The other belief, that the LSA is getting better over time, is also entrenched. I'm no true believer in burn-in time or whatever it's called, but I can't help but notice that the LSA keeps delivering more beautiful music with each passing week. I can't explain either phenomenon; I don't care to. Fiddler, It may be friendlier than tubes, but one weakness of the LSA is its one input design. I understand and appreciate the argument that more inputs would be sonically compromising, but if I didn't primarily use my turntable, I would find constantly switching interconnects a serious pain. |
So if he doesn't like Fets or Mosfets the input stage to the Samson must be bi-polar, it is not tube as it's all solid state. This means the Lightspeed Attenuator is maybe not giving 100% of it's self, if the Samson is bi-polar input they (poweramps with bi-polar inputs) are usually below 30kohms input impedance. We have found in listening tests with many "golden ears" that the Lightspeed Attenuator just starts to compress the dynamics slightly at 33kohms, 47kohms was fine, indistinguishable right up to 200kohms. Cheers George |
It may be friendlier than tubes, but one weakness of the LSA is its one input design. I understand and appreciate the argument that more inputs would be sonically compromising, but if I didn't primarily use my turntable, I would find constantly switching interconnects a serious pain. Like you I also play a lot of vinyl, but do listen to CDs and on occasion my tuner and reel tape deck. At first changing the ICs was inconvenient, but I got used to it. I had done some research on input switchers. You can get them pretty cheap, but if you're concerned about sound degradation Decware makes one for $119: http://www.decware.com/newsite/rotary.htm This has 6 switchable inputs. You could probably get them to make you one with less. Steve is pretty flexible. I know, another set of interconnects. Well the Decware ICs are fabulous for the price. All told you'd be out less than $300. Consider it the price of convenience. Of course if you want to splurge then the 47 Labs input chooser is the one to get: http://www.sakurasystems.com/products/47selector.html A cool $850. |
