Clio09 - thanks for taking the time to do your homework before your great answer above. While I intend to purchase the LIO-8 DAC I am currently using an antiquated Sony 5 disk player (CDP-CA7ES) which has an output impedance and voltage of 10K ohms and 2volts respectively.
Knowing these specs now, does it change anything in your answer Clio09 or am I still 'safe' in that I'm not missing anything sonically by having the volume control low at 8-9 o'clock?
Off topic - was the DIY Skyline Diffuser write-of of mine helpful / useful for you? |
Just looked at the specs of the Sony CDP-CA7es and the 10k for the output is the min load recommended, I would say with this figure it has an output impedance of around 200ohm which is fine.
You will not do any harm to anything using the Lightspeed at 8 or 9 o'clock, the only detriment is the range you have is minimised, sound will be the same with good interconects at 9 o'clock or at 12 o'clock and with 180kohms input impedance this is a great high input for any passive.
Cheers George |
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The DIY diffuser write-up was helpful, but after looking at your system page I'm more interested in those wooden hemi cylindrical diffusers. They look great in the room.
Well at least the Sony has legible specs for the lay person. You are in good shape with the LSA so not to worry. |
George - thank you for chiming in. Glad to hear that no sonic purity is being lost at 8-9 o'clock than further around the volume dial.
Clio09 - Hemi-cylindrical (polyfuser) diffusers are much easier and faster to make than Skylines of similar size. Email me if/when you wish to consider tackling them.
Happy listening all. |
Can you guys tell me how the compatibilty would be in my setup?
Quad CDP2-99 / 2.4 V rms max output
ASL 1009 dt / 100k / 1v input sensitivity
1m & 1.5m TG audio hsr ic's and speaker cables
Sonus Faber Guarneri
Much thanks. |
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You would want to use the fixed outputs, not the variable outputs on the CDP, but you probably already knew that. Atkinson measured an output impedance that varied according to frequency, but was in the 120 ohm range so I'd say you're good to go considering the other information provided. |
Thank you Pubul57 and Clio09...I think I will give it a try. |
Just a Heads up for any looking for a very low capacitance cable. DNM interconnect is 13pf/meter. Now thats some low capacitance cable that may be a help to Lightspeed users. |
Cardas GR, 12pf/ft. Lstack, sure that's not per foot? |
No need to do the A typical Audiophile thing here, and go overboard.
So long as you have 100pf or less per foot, that's fine as this gives with 1mt a -3db 76khz, this is over kill anyway as the cd filtering is lets face it already cutting in the mid 20khz anyway, so you won't gain anything by going even lower that 100pf per foot. No need to waste money, KISS
Cheers George |
DNM datasheet states 13.2pF/meter:
http://www.dnm.co.uk/datasheets/stereointerconnectall.pdf |
Wow! That has to be the lowest capacitance if any cable - no? But like George says, I feel safe with the 12pf/ft:) |
I was rading a review of some VH Audio Power Cords" by Jim Merod for Of Sound and Music. I beleive he is a recording engineer - if that matters. in the context of that review he said something very appropos to the LSA experience, I why I love it:
"No superior power cord should "enhance" music by adding dynamic slam or transient bloom or etched imaging. Sometimes one may be tempted, hearing such artifacts, to believe that such "more" is good or better...or amazing. Such artifacts are exaggerations that distort or attenuate the relaxed vivacity of well-recorded sound. All audio equipment should be sold with a generic disclaimer: Do Not Be Fooled By Sonic Cartoons!"
I think the LSA is a "preamp" Jim Merod could love. |
I was actually "reading" it:) |
That has to be the lowest capacitance if any cable - no? The extremely low capacitance results from the flat construction with wide spacing of the conductors. 300 ohm antenna twinlead has similarly low capacitance. The lack of shielding could be a problem in some setups, though. Also, the relatively high resistance and inductance of the return conductors (compared to what a shield would provide) might also contribute to ground loop issues in some systems. Best regards, -- Al |
I have a wallwart I purchased from Circuit-Test. It is 12VDC, 400mA, and is a linear power supply. Absent a battery PS which may sound better, is that all I need in an AC adapter? |
linear and regulated - whatever that means. |
Yes, you want the linear regulated PS, not a switching PS. 400mA is plenty. No need to go the super beefy route with the LSA. Of course you need the correct pin adapter with center pin positive too. |
That's what I have:) The battery test is next! |
George, this may be an odd question to ask a designer, but can you envision any future implementation that might sound even better in a passive friendly environment (no need for gain or buffer)on the LSA? I mean sonics. Sure cosmetics could evolve, perhaps some more I/O flexibility, but given that this is the best sounding "preamplifier" I have heard in my system, and that you have been sorting it out for 30+ years, is the any room for improvement that you can envision? |
None really, it's maxed out because of it's simplicity, the siganl travels through one soldered resitor only with no volume pot contacts or other contacts in the signal path.
All that could be done is to 12vdc battery power it, but that is a very very small gain, most cannot hear a difference over the shipped wall wart.
The difference in supply noise between the battery and wall wart at the Lightspeed's output is microscopic using the very best test gear. "It is in effect noiseless"
Cheers George |
I can think of one: If a remote were built into the product, the actual volume control system (as a module) could plug directly into the input of the amplifier (with separate left and right hand channels) rather than being in a box that needs an interconnect at its output.
In this way, the interconnect would play a lesser role in the resulting sound as it would only be used at the input and not at the output. IOW you would then be able to get around the traditional problem that affect all passives- the inability to drive a cable. In this system the remote would be mandatory, but it would be easy to build balance and mute functions into the system. |
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Sounds good to me. Seems like remote LDR options exist out there, but wonder if there is any negative impact on the sound using a remote feature.
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No negative impact using a remote, but no improvement in sound either, but there is a negative impact using any form of input or output switching.
It has has always crossed my mind to do a remote volume, but as it is the Lightspeed Attenuator has 99.9% reliability for minimum dollar expenditure.
Put in a remote receiver sensor circuit, a motorized pot and a good quality remote control, plus another 2 power supplies one for the receiver circuit and one for the motorized pot. And you have diminished that reliability by quite a bit. Plus you need a bigger chassis to house it all, and you have increased the price 3 fold. The cheap skates are already complaining about the $470 shipped price, can you imagine if it were to go over the grand mark.
I have a "KISS" reflection every now and again to bring me back to earth to make me realize why it is such a good product to begin with, and if it ain't broke don't ---- with it.
Cheers George |
On the famous DIY thread, it appears that have some tried the remote route, but it requires some drift from the purity of sound you get without it. I would be willing to go with a manual "Endler" approach, but it would be a bit inconvenient getting changing volume levels and rebalancing channels. |
Reliability is golden. I certainly would not be interested in paying 3x for remote - I'm really not that lazy:) What about the idea of LDRs at the amp input - no IC? Endler Style Attenuators with the superior Lightspeed LDR attenuator. |
I have the EVS attenuators and the concept is pretty sound in terms of being able to put them at the amps inputs. Not sure you could get the LSA to accomplish the same thing since each unit would probably be larger in size than an EVS or Endler making them a tight or impossible fit on some stereo amp inputs (monoblocks should be much less problematic). Not to mention I assume each will require it's own power supply or share a power supply that sits off to the side somewhere. |
You know Anthony, it just might be that the LSA is what it is and the way it must be:) Some of the DIY community seems to be hell bent on "improving" the LSA - it's just possible it can't be done - without trade off - thought it would be nice to get rid of the ICs. One less thing, but as you suggest an added element of complexity. |
To reconfigure it and have it so it plugs directly into the poweramps rca's, would be a nightmare to do. As there is no standard distance between left and right rca's on a stereo poweramps and then there's monoblocks to contend with.
You would have to make two independent Lightspeeds each with their own power supply, they would need to be about the size of a cigarette packet each, this would be hanging of the amps rca's, and because it's on the back of the said poweramps, they would need to be remote volume, so double the size of those cigarette packets and you have your nightmare.
KISS KISS KISS KISS KISS
Cheers George |
The only other possibility is to put it inside the actual amp at the input. It would require enough chassis space, but it can be done. This is Ralph's approach with the passive attenuator upgrade for the M-60 amps and up in his line. Unfortunately not enough room in the S-30 or Iwould have opted for it. |
George, I appreciate that you want to keep it simple but you already have that product. If something was created pretty much like you and I have described, it would be better, but it would not be as simple. But that's OK- there would still be a market. |
Like I said two lager than cigarette size boxes hanging off each rca on the back of the amp/s, and a third power supply unit, you need a remote volume control as they would be behind the amps, then there's the problem of the remote receiver in both units not picking up the remote controls signals because they're being block by the amp itself.
Then there's the price, definatly tipple or more, I doubt anyone would buy it after you've tooled up for all this, like I said a nightmare, but for DIY'ers worth a shot to get rid of one set of interconnects.
Cheers George |
Of course, if your amp has its inputs in front.... Anybody on this thread have any leads on a monoblock w the inputs in front???? Paul, Ralph, anyone???? |
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There's a stereo amp with inputs in the front too;) |
Just picked up one of the preamps today on the 'gon, mkII. I will be using it with 1 meter ic's into a Krell KSA 50S amp. It has 49 kohms input impedance, output impedance .28 ohms, max output voltage 75.8V and source is 2.5V. Do these stats add up to a winning combo with the Lightspeed pre? |
You have no gain issues. You should no IC capacitance issues (with most ICs) and you should be ok with the input imepdance of the amp. The higher the better, but I think you are on that safe side there too. |
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Have a level one plus modded Music Hall 25.2. Gain is 2.5V. Just ordered a NAD 565 BEE. Gain is 2.2V. IC's are AU24,Straley Reality and Morrow. |
The Music Hall is a DAC? They use an tube output stage? |
I am asking because the output impedance of the DAC or CD Player is also an important part of the passive equation. Most SS players pass the test, a tube output stage could present some issues, but George would be better on commenting on that. |
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They are both solid state CDPs, should be fine. I'd recommend a shielded IC between the LSA and amp. I think the Reality cables are shielded, not sure about Audience. Morrow are not shielded. |
I'll check into the shielded vs. non shielded issue. I know my Morrow's are noisier than my AU24.What shielded ic's do you recommend? Hey Clio I saw you have have the Tel Wire powercords. I have them on my preamp and CDP. They are very,very good. Don't come across too many guys who have Tel Wires. What do you think of the HC powercord. I currently use original Lesslosses on my high current applications. |
I use Mogami: http://www.audiogon.com/cgi-bin/cls.pl?cablintr&1303312915&/Mogami-RCA-1m---studio-standarAlternately I recommend a cable that uses a Litz geometry as it is noise canceling by design. One such cable is the one offered from Q Audio. The TelWire power cords are the best I have found for my systems needs. I use the HC cords on my amps. There are more people who use these cords than you may suspect and for very good reason. Extremely neutral and simple design. Dealer Disclaimer: I resell Q Audio and TelWire cables. |
Anthony do you know if the cable in that RCA is Mogami 2534 or 2549? Capacitance for both seems very low:) |
2549 and they are low capacitance. Just a simple shielded cable design. This connects the LSA to the S-30.
Roger Modjeski first introduced me to Litz as he uses this geometry in is top line cables. Litz in general yield low capacitance and superior noise rejection. I use a Litz cable between the LSA and RM-10 and EM7 amps. |
