The attenuation range does not go low enough so even at full counter clockwise setting you will hear some music coming through the speakers, albeit at very low volume. My Joule Electra LA-100 MkIII was like that too.
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
I kinda think it is the best volume control ever. I've tried full preamps from ARC, Rogue, Placette, some TVC, battery tube buffers with goldpoints and a few other oddities in a vinyl only system. Can't duplicate the blackness and the natural ease of the musical flow. Fantastic product. The DIY ones (boards offered with George's blessing I'm told) sound equally great if you need to create something that matches the look of the rest of your system or need multiple sources. |
What is your concern? You have very high gain speakers and very high sensitivity amp and are concerned that you cannot get the volume low, in fact to high for background music? What gear do you have that gives rise to you concern? With my 89db Merlin's, and .8v RM10 amps there was no problem at all, though you can not make it absolutely silent, if you need to do that, I don't think you can use an LDR.. |
I sold the LSA and just got the Emia a few days ago 9 can't imagine many have been sold yet) (currrently $1,250) because I felt the need for balance controls (room, ears, recordings). After sometime assessing the Emia, I will also be getting the LSA with dual volume controls to compare A/B as I did not have both at the same time - though without "steps" might be a PIA making adjustments. To some extent, Clio9 has already made the comparison between Emia and LSA as he owns a passive based on the Slagle Slagelformer AVC, which is essentially identical to the Emia, though Emia makes "artful" cases. Clio9 seems to love both with a slight preference to the LSA, which might very well be system dependent (he wrote a "review" comparing them on Agon). Obviously the AVC is more"impedance flexible" than the LSA, but the LSA purer, and considerably cheaper. Whatever the case, from the time I have had with the Emia, and Clio9 with the LSA, they are both wonderful passives, and if passives can work for you, both worth considering, the LSA being the obvious bargain financially, and in the right system, perhaps sonically too, as there is simply less there interfering with the signal than with an auto former, but you signal may need "conditioning" to work optimally depending on your system. I think Clio9 has heard more passives than any person in the western hemisphere, and LSA seems to be his preferred option as this time, but there are other options that might be better suited to certain system requirments. In my system the LSA was unimpeachable sonically - at least for my taste. If you need absolute attenuation, the LSA may not work, how sensitive are your speakers, what is the voltage of your source[s] and sensitivity of you amp? George or Clio9 might be able to give you and idea of how much of an issue it might be for you - in my case it was a non-factor. |
If indeed the EMIA uses the Slagleman autoformer modules with the circuit board designed by John Chapman then the only nit I have is the inexpensive switch used. If they use the OEMed modules that John Chapman offers (which I think is the case with the remote version), then this would change things somewhat. Paul, have you peeked inside yet? Can you tell me what version of the autoformer is being used. I have to admit Jeffrey Jackson does outstanding woodwork. I have decided to have my woodworker build me a nice box and I will re-house my Slagleman modules inside it. |
Anthony, it looks like the Slagle auto former with the Chapman board is the one being used, I take it that is a good thing. I assume the Bent TAP-x I owned with the Slagle a few years back was using exactly the same thing. Getting silence at "O" seems to be impossible with the current LSA MKII design, where as the less good sounding MKI could. I'm sure George will be able to explain why. |
Paul, yours will either look like this (pic at top of page): http://www.intactaudio.com/atten.html or this (pic at top of page): http://bentaudio.com/index2.html Mine has the first one. The later Tap-X units have the second one. |
I see that George recommended lowering my gain of the amp or source. My amp input impedance is 47k ohms and output impedance of my DAC has been confirmed at 600 ohms by Rega. What numbers do I need to look for in an amp or source to match with my 98 DB sensitive speakers so that I achieve lower volume in the "0" volume setting? |
I don't think it has much to do with impedance. It is the input sensitivity of your amp, it gets to full power output too easily. For example, my amp I use with a passive only needs .8v to reach max. power output. My other amp that I use with an active line stage requires something like 2.8 v to reach max. output, and in most cases requires the gain provided by an active line stage. The other side of the chain would be to reduce the output voltage of your source so the overall gain structure is lowered. I have no idea how you do any of that. No matter why you do, the LSA in any system that it is appropriate for will still produce some volume a zero setting, and just should not be that intrusive, except with high sensitivity amps and speakers combined. |
04-12-12: GooddominoSensitivity (the input voltage that will result in the amp putting out its maximum output power) is not directly relevant. What is relevant is the gain of the amp (the relation between output voltage and input voltage). Comparing sensitivity numbers is only meaningful if put in the context of the power capability of the amp. For example if two amps both have an input sensitivity of 1 volt, but one of them is rated at 50 watts and the other at 500 watts, the 500 watt amp will produce much more volume in response to a given input signal than the 50 watt amp will produce. The suggestion George made earlier about trying a pair of Rothwell attenuators seems to me to be well worth trying. They would be connected directly to the input jacks of the amp, with no intervening cable. In conjunction with the 47K input impedance of your amp, the 10 db version would result in the LSA seeing a load impedance of about 30K, which is on the low side but I suspect would still be ok, given that it won't vary significantly with frequency and given the 620 ohm output impedance of your source. I am not familiar with the characteristics of the 20 db version, but I would guess that it would present a load impedance that is significantly higher (and therefore even better). Regards, -- Al |
There is nothing wrong with the gain structure of your system IMO. As George mentioned get a set of Rothwell attenuators. I believe they come in a 10 dB and 14 dB version. Also, I think Luminous Audio makes interconnects with resistors built in to attenuate the signal. This is going to be the simplest way to lower or eliminate the volume at "0". Do you have a SPL meter? can you tell us what the sound level is at your listening position with music playing and the volume at "0". |
If I knew about the Rothwells I might have kept the CAT pre/amp combo. Even though the pre and amp were "made for each other" I could not go much beyond 9-10:00 with digital sources, and with a stepped attenuators to boot! If George, Al, and Anthony all vouch for the Rothwells to solve the "problem", it seems it is a safe bet, and easier than changing amps:) |
04-12-12: AlmargI should add to this statement, though, that since on occasion you have used your volume control as high as the 2 o'clock position, I'm uncertain as to whether or not the 20 db attenuator would still allow you to reach those same maximum volume levels, even at the maximum setting of the volume control. Regards, -- Al |
Yes, the transport has no relation to the issue. The problem is that DAC's (and also CD players) usually have maximum output levels of 2 volts or more, which is unnecessarily high. Stereophile measured the maximum output level of your particular DAC as being 2.17 volts. As a rough approximation the outputs of tuners and other analog sources are often just 1/3 or so of that amount, which is about 10 db less. Regards, -- Al |
Wow this threads been active since I went on an outback holiday to the deserts of Australia for the last week. As for some of the questions asked. When the power is disconnected from the Lightspeed Attenuator both the series and shunt ldr's go high in resistance to around a few megohms they never go open circuit, so even with power disconnected they still allow some small amount of signal to pass through. As for never being able to go to zero volume, most do not find this a problem as if they want zero they can mute,pause, or stop the source with the remote. If the source is vinyl the gain of phono stages are quite small compared to a cdp and is never a problem either but a very small signal can be heard through the speaker if next to them. Saying this if someone has one of the many clones getting around, most use the NSL32SR3 led/ldr combo, these do not go as low in volume as the NSL32SR2S that is used in the Lightspeed Attenuator because the minimum resistance is higher on the NSL32SR3, and cannot be shunted to ground as well as the NSL32SR2S. Also some clones are using the MkI Lightspeed circuit which I first used 25 years ago, which has one a fixed value resitor for the series component and a ldr for the the shunt component, these are far cheaper and easier to make but are quite high in volume at minimum and also don't sound as good because of wildly differening I/O impedances. Cheers George |
This thread truly has a life of its own! I regret to inform all those who may have followed this discussion for the past two years that my friend and fellow Audiophile Paul Rosenthal who is known to you as Pubul57 has passed away suddenly earlier this week. I was happy to know him for the past ten years in Baltimore and he exposed me to a plethora of equipment, advice and insight during that time. Paul loved many fine things and had many great friends. I know he cherished the time he spent on Audiogon with all of you. I know I cherished the time I spent with him, he was like the big brother I never had. I hope you will continue debating what the best source is, or when is absence presence and remember our friend Paul; audiophile, philosopher, and friend. May he rest in piece. |
This is quite shocking and sad. My condolences go out to his wife and family. I met Paul here via Audiogon and had the pleasure of meeting him and spending a weekend with him at the RMAF a few years back. He was as gracious a person and as passionate an audiophile as he was here on the forum. In fact, I was just speaking with him last week as we were discussing one of our favorite topics, passive preamps. May he rest in peace. |
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