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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.
pubul57
georgehifi's avatar
georgehifi
10,312 posts
 
In the beggining of this thread @clipsal mentioned that First Watt B1 killed his Lightspeed Attenuator in terms of dynamics.


This could be true, in most systems the Lightspeed is a great match just like many tube pre's are, this could have been an instance where it or a tube pre's was not.
clio09 and the originator of this thread (rip) pubul57 asked clipsal what were the other components, alas he was never to be seen/heard  of again???
 
https://forum.audiogon.com/posts/75827

Cheers George
clio09
3,374 posts
 
@chakster, what phono sources would you be using? I think this will have some bearing on the result. I have heard the B1 but have not been able to compare it to my Lightspeed. I have compared my Horn Shoppe Truth buffered preamp to the Lightspeed and there is a thread here that discusses the results. Quite frankly, of all passive, buffered, and unity gain devices I have tried, the Lightspeed is the one I still use. Your input impedance on the FW amp is on the cusp, but I have used my Lightspeed with a solid state amp with a similar input impedance and had no issues.
chakster's avatar
chakster
6,144 posts
 
@clio09 

I have various phono stages, but Austrian (out of production) WLM Phonata Reference and new Australian JLTi is what i use the most. Funny, but the cabinet of my JLTi prono stage looks exactly like the cabinet of the Lightspeed device.     
georgehifi's avatar
georgehifi
10,312 posts
 
Australian JLTi
Funny, but the cabinet of my JLTi phono stage looks exactly like the cabinet of the Lightspeed device.

I know Joe very well, he used the same Hammond case after he saw my Lightspeed. The phono stage is a simple opamp riaa input and a opamp buffer output.
http://img.usaudiomart.com/uploads/large/699066-vacuum_state_jlti_phonostage.jpg

Also the WLM Phonata is even simpler just one riaa opamp with transformer coupled output could even have capacitor coupling as well seeing that black poly cap near the trany.
https://c1.staticflickr.com/7/6139/5955227066_d440161037_b.jpg

Out of the two, just from an eyeball view, I would say Joe’s JLTI would have it over the WLM.


Cheers George
chakster's avatar
chakster
6,144 posts
 
@georgehifi not sure how anyone can judge by the picture (and it’s a bit off topic), but the picture of WLM you have posted is unfinished unit.

1) This is the actual picture of my WLM Phonata made when i opened it to upgraded load resistors to Vishay Naked Foil 100k Ohm for MM input (i prefer 100k over 47k for nearly all MM cartridges):
https://pbs.twimg.com/media/DaEOa5DXUAA892A.jpg

Technical Data:
MC-Input Impedance Range: < 100 Ohm to 50kOhm
MM-Input Capacity: 100pF
THD (Total Harmonic Distortion) @ 1kHz: 0.01%
SNR (Signal to Noise Ratio) MC: >72dB
SNR (Signal to Noise Ratio) MM: >85dB
Max. Input Voltage for MC-cartridges (theoretical value): 1200mV @ <1% THD
High Performance, Professional Type Step-Up Transformers

The PHONATA offers utterly precise RIAA equalization:
• RIAA equalization is implemented across two amplification stages (within current amplification), providing a frequency expansion from 10Hz to 50kHz (Subsonic cut below 10Hz). Selected components (1% tolerance) are used.
• RIAA equalization can be selected from two positions with a switch at the back of the unit (position “high” for records produced before 1965 or to improve the performance of somewhat “darker” sounding cartridges at higher frequencies. This position provides +3dB equalization as from 5kHz and +6dB as from 10kHz.) • Position “low” for all other records.

The unique feature of PHONATA is automatic adjustment of Load-Impedance for MC cartridges, but i use this phono stage mainly for MM cartridges nowadays, sadly a few units were made before the company closed the business, WLM speakers were quite nice, their tube apms were made by Trafomatic Audio (and i have one of them - WLM Minueta).

2) Phonata has much better bass response than Joe’s JLTi phono stage, the difference is huge (but the price difference is also very big). I like JLTi phono stage too, RCA plug load resistors on the back is such a great feature! If you want to look at the JLTi you will see it’s even simplier and smaller. This is the actual picture of my JLTi (inside).

For LOMC cartridges i use ZYX CPP-1 Pre-Preamp favorited by Arthur Salvatore (his name has mentioned in this thread many times).

And Luxman AD8000 with 8030 silver SUT for LOMC with extremely low impedance.

None of the mentioned phono stages can handle LOMC as good as the LUX silver SUT or ZYX CPP-1 headamp. So for MC i use those phono stages as MM mainly to connect my SUT or Headamp.

P.S. I hope i will find the right phono stage or sut to handle my 0,05mV Ortofon MC2000 cartridge, maybe now when i have so much power with First Watt B1 + First Watt F2J i have to try it again with my existing phono stages. We will see.    






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