Okay, dumb question. I have an Arte Form i-150 integrated amp with dual light speed attenuators in it. What does that mean? Is that different that what this thread is about or is it just a type of attenuator that can be put into any preamp or integrated?
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
Congratulations George, the Lightspeed pre/attenuator is just magic. When I was a little boy I had the opportunity to listen to a RCA horn record player (His Master’s Voice) and I was intrigued and fascinated to hear music from it. Many years later I had the opportunity to witness the launch of the CD when I was working for Philips (Chile). The sound quality was impressive compared to the records and the impact to the guests was so big that the audience got up applauding the music. Today I offer my applause to you; the difference in listening to CD’s throughout the Lightspeed and other preamps or just the volume control, reminds me of the experience I had of the difference between vinyl and CD. Congratulations. |
From a customer who has both the Lightspeed and Eva II ----- Original Message ----- From: Sirot Seta To: George Stancheff Sent: Thursday, December 23, 2010 4:32 PM George, The lightspeed is great and is "light" years ahead of diyparadise's EVA II. It is much quieter and linearity is perfect. BTW I wrote a review of a DAC and did mention the use of the Lightspeed, just FYI. http://www.digitalaudioblog.com/2010/12/review-db-audio-labs-tranquility-dac.html Regards, S Cheers George |
At the DIY Audio LSA forum http://www.diyaudio.com/forums/analog-line-level/80194-lightspeed-attenuator-new-passive-preamp-391.html the EVA is mentioned. Here are some comments from George. I've neve heard the EVA so can't comment one way or another. It would be nice to have multiple inputs and remote, but then it might not sound the same.... "And there's where your HF noise is comming from, a dirty switch mode power supply. And from a high res photo of the guts I was sent by an anonymous sender, they don't use Silonex NSL32SR2S's, it's a far cheaper one so they can max out on profits, and to boot they have input and output mini relays in it, this is the exact reason for the Lightspeed Attenuator, "it's to get rid of all contacts between the source and poweramp" not add more contacts, no wonder it does not sound as good. But it does look cute, with remote and digital readout, this will attract the naive customers. Cheers George" __________________ |
for the same price, or less, (~$395 shipped), i would strongly recommend the diyparadise eva-2 ldr attenuator - this sucker actually improved my sound, (i use an active preamp), by enabling me to run the (already wery transparent) melos tube potentiometer in my highly modded ma333r wide open. the eva-2 is the real deal, imo... 3 remote-control inputs, remote wolume... and yes - ldr http://diyparadise.com/shop/index.php?main_page=index&cPath=18 http://diyparadise.com/shop/images/P1012169.JPG doug s. |
A warning from George on a DIY forum: Got 5 x fakes from these guys in Hong Kong " buyincoins_au " the batteries were ok but all the chargers blew up and fried on 240v or 110v after 15mins of charging time LETHAL!!! 12V DC Rechargeable Li-ion Battery for CCTV Cam 1800mAh (eBay item 190459066434 end time 19-Jan-11 17:50:02 AEDST) : Electronics The weight to send all back cost more than the purchase, thankfully I did a Paypal claim in time and they refunded me. Cheers George |
Good point. The prongs which can be seen peeking out in the photo of the charger kind of look like it's probably USA-compatible. And the three adapter plugs it pictures further down the page are obviously not for the USA, which would seem to imply that the built-in plug is USA-compatible. George, can you confirm that? Also, a number of Hong Kong sellers offer similar battery assemblies on eBay, indicating that they are supplied with whatever plug type corresponds to the buyer's country. Search under "12V Li-ion Rechargeable Battery CCTV." Best regards, -- Al |
Re batteries vs. wall-warts, perhaps the reported sonic differences are due to voltage differences? I realize that the Lightspeed contains an internal 5V regulator, but perhaps differences in the "12V" input voltage result in different internal operating temperatures, perhaps affecting sonics in some way. Also, as a point of information, lead-acid batteries (such as the one Anthony linked to), exhibit much greater changes in output voltage as a function of charge state than lithium-ion batteries do. Best regards, -- Al |
Oh I forgot. I agree with George. I sensed the sound was different using the battery power supply, but can't really pinpoint exactly what it is except to say that I felt the lower frequencies were affected. I know there was no difference in noise level, at least from what I could tell by just placing my ear next to the speaker. With my Music Reference RM-10 it was dead silent either way. |
The battery I use is the same one the designer of my turntable supplies for the motor pod of the table. It can go days without having to be recharged. In fact I actually went and bought the next model up because it allowed me to run two pieces of equipment on battery power (I have a preamp that could be connected to it too). So far with just the LSA connected I haven't had to recharge it once, and its been 45 days. |
Everyone who has bought one, including Sam Tellig from Stereophile has said they think the battery is better than the wall wart I supply with the Lightspeed Attenuator. But it's a small difference, and they cannot say what the differences are, this also includes myself. I think maybe it's psychological perhaps. It cannot be noise as the supplied wall wart into the Lightspeed measures 200uV of noise on the output, that's not mV (millivolt) but uV (microvolt) this is undetectable. Cheers George |
This is the best battery, it's Lithium-Ion, rechargable (no memory problems) lasts about 12hrs on the Lightspeed before recharge got all the right leads, on/off switch for the Lightspeed an neat sits on top. And cheap. http://cgi.ebay.com.au/ws/eBayISAPI.dll?ViewItem&item=320645701036&ssPageName=STRK:MEWAX:IT Cheers George |
Battery or wall wart? If you want a battery PS look here: http://www.sears.com/shc/s/p_10153_12605_02871486000P?prdNo=2&blockNo=2&blockType=G2 You will also need this: http://www.minute-man.com/acatalog/Online_Catalog_Cigarette_Ligher_Plugs_and_Sockets_272.html#a90_2d618 |
I would say that with this low 83db speaker, your amps input sensivtity would have to be between 1-1.5v to have compatibility with the Lightspeed Design. But then seeing your amp is beastly 500watt rms, you would never use all this into (I take it their Maggies), so you could afford to loose some., I doubt you would even hit 250watt into them. Cheers George |
Thanks Ralph is a very important bit of information and affects the advice given for ideal matching, especially since there seems to be a phobia, or worry that turning the volume control to high is somehow stressing the system in some way. As this relates to the M60s, does that suggest that it is best to set their gain at minimum settings based on the same reasoning whether using the LSA or MP-3? |
Jult52, you have no worries, in fact this is more of an ideal situation (so long as you can get the amp to make satisfying power)- you *want* the amp to have less sensitivity than the maximum level of your source, as this allows you to run the passive volume control at higher levels. The math works more in your favor in this case- you are less likely to loose bass and impact since you will not be running the volume control at a lower level. When the amp has higher sensitivity, so that your source makes more voltage than you need, then the math works against you; with any passive as you turn the control down more, the more bass and impact is reduced. |
George, note that the issue is not whether or not the volume control will have to be used too close to the bottom of its range. The issue is that even with the volume control set to its maximum position, a substantial fraction of the power capability of the amp (perhaps half) will not be able to be utilized. And keep in mind that the gentleman's speakers are relatively insensitive, at 83db/1W/1m. I doubt it will be a problem, as I indicated, but that is the issue. Best regards, -- Al |
I think you'll be fine. Your CD has a good amount of output voltage and your amp isn't too insensitive. You should definitely be able to swing the volume knob past 12 o'clock which is ideal. I do use my LSA with the S-30 single ended inputs. I've also removed two of the driver tubes and shorted the tube sockets, effectively lowering the gain of the amp 12db. In each case the LSA worked fine. My speakers are rated 92db, but that is conservative. 94 or 95db is probably more accurate. Had they been under 90db I doubt the LSA would have worked well with the S-30. |
All this is not an issue, most amps/speakers are fine. If you have an amp that is .5 or 1v input for full output sensitivity and 110db speakers, then you my have a problem with having to use the Lightspeed way down on the volume and never being able to go past 8 o'clock on the volume. And an active pre would be even worse in this situation. But this is very rare as most amps are 1.5 to 2v sensitive and most speakers are 93db below. Cheers George |
So, yes there is a slight loss in max power, but do you think it would be relevant?My guess is that it would not be a problem, especially considering this statement by Jult52 in the other thread: My power amp has a continuous rated output of over 500w which I never fully max out being a law-abiding middle-aged person :) I like the power for the instantaneous peaks, especially at the onset of sounds and for the feeling of headroom.BTW, my rough estimate of 3db as the amount of the amp's power capability that would become unusable was based on the following: 1)1.3db due to the disparity between dac output voltage and amp input sensitivity. 2)0.5 to 1.0db due to tolerances or possible inaccuracies in those specs. 3)0.5 to 1.0db estimated margin in the recording, between the highest musical peaks and digital full scale. That's what I've actually seen on a number of commercial cd's, that I've analyzed with an audio editing program called Sound Forge. Best regards, -- Al |
Almarg, I suspect you are right, Ralph's spec sheets don't specify single-ended sensitivity specs. So, given a 3db loss, or a 50% reduction in wattage, assuming a worse case scenario, it will seems Jult52 more than sufficient power to drive his speakers VERY loud in most rooms, I assume Maggies are not for headbangers. So, yes there is a slight loss in max power, but do you think it would be relevant? But then again I come from drive my Merlin VSMs with 27-60 watts amps. |
Paul, I'm not certain but I suspect that the reason for the Atma-Sphere S30's high sensitivity number may be that it reflects the voltage DIFFERENCE between the + and - signals at its balanced input, which would be twice the amplitude of either signal. Not sure how its rca input is configured, or if the 3V sensitivity spec is meant to apply to that input as well as to its balanced input. Also, although I realize you were referring to a 92db speaker just in answer to Jult52's question about "why does it matter," it's worth noting that the MMG's sensitivity is spec'd at 86db/2.83 volts/1 meter, which for its 4 ohm nominal impedance is only 83db/1 watt/1 meter. Although as a planar speaker its acoustic output will fall off relatively slowly as listening distance increases. Jult52, the only ways that occur to me for stepping up the dac's output voltage would be: 1)Putting an active gain stage somewhere in the path between the dac and the power amp, but of course that would defeat your purpose in using a passive preamp. 2)Modifying the dac internally -- lots of potential issues there. 3)Using some sort of audio step-up transformer -- lots of issues there as well. Best regards, -- Al |
That is above my pay grade:) I think George could answer the DAC question later today (he is in Australia) - mine has a 2v or 4v switch, but that seems to be fairly uncommon. Yes I do think you would loose some ouput potential, but with your kind of power and your current speaker I'm not sure you would be able to hear any difference. I assume you have a SS amp, I would think the impedance match might be more of an issue than sensitivity (with most, not all SS amps). |
Pubul - I see. So you are saying that I would indeed lose some of the amps output potential due to the mismatch between the voltage output/input gap. Is there a solution to the mismatch other then changing to a different amp or DAC? Can DAC output voltage be increased? (I know it can be decreased by installing a resistor.) |
I asked this elsewhere but wanted to move this discussion here since it concerns adding an LSA to my system. I've read a lot here about DAC output impedance and power amp input impedance but less about sensitivity. To give an example, my DAC has an output voltage of 1.75v and my power amp has an input voltage of 2.1v. So that isn't an ideal relationship for passive preamp purposes but my power amp has a continuous rated output of over 500w which I never fully max out. At what point does the difference in the DAC output voltage and power amp input sensitivity become a problem? How does this problem affect the sound? And if you never push your amp to the outerbounds of its volume capabilities, does it really matter? Interconnects would be pretty short and impedance out (100ohms) and amp impedance in (62k ohms) shouldn't present a problem. In the other thread, Almarg responded with some good information and estimated that the output/input voltage discrepancy of 0.35v represented a reduction in volume anywhere from 1.3-3.0db, which effectively means reducing my power amp to maybe the 200-400w category, which is undesirable. What are your thoughts? |
I'm using a content management tool for the layout and publishing. The forum module was very easy to work with. Not as robust as some other third-party options, but since this is the only forum that will be on the site and I don't expect heavy traffic it works for me. Electa-Fidelity is a playground. I don't expect much from it. Just wanted to do something fun and interesting with my spare time, as well as try to help a few friends out. Now I guess on occasion I'm going to have to add disclaimers on my posts here. What a PITA. |
