[cporada]

Hi Paul
I’d be using the LDR between a Marantz sa15 SACD player (2.1V output) and my 100 wpc solid state power amp (1.5V input sensitivity, 30db gain, 50kohm input impedance). I've e-mailed Marantz to find out the output impedance of the SA15s1, since that's not in the owner's manual.  George seems to think this would be a good match for the LDR, but I'd be glad to hear your opinion as well.
Thanks so much for all your help and best regards,
Chris

[JoshK]

Sounds like this would work well for you.  The poorserbianman kit would probably also work if you need the buffer. 

[cporada]

Hi Josh
Thanks so much.  What does the poorserbianman's kit do that the lightspeed won't, i.e., can you explain why I may or may not need a buffer?  Also, is the PSMLS available assembled or only as a kit?
Thanks
Chris

[dweekie]

Hi Josh
Thanks so much.  What does the poorserbianman's kit do that the lightspeed won't, i.e., can you explain why I may or may not need a buffer?  Also, is the PSMLS available assembled or only as a kit?
Thanks
Chris

The PSMLS will do balanced signals.  It'll be just a pcb board and LDRs.  I don't think you'll find any complete kits or assembled units (besides George's) since it is George's contribution to the diy community, similar to Nelson Pass's First Watt units.  The buffer is for impedance matching, and ideally you would want to avoid it if possible.  However, if your amplifier has low impedance relative to your source, you will benefit from having the buffer.  I think <50k input impedance would be a very rough guide for benefitting from a buffer, but I've used the LDR attenuator on far less, so I think you will have to play it by ear, literally 

[TomS]

The PSMLS can be used with or without buffers, as well as balanced or single ended.  He packages them with the pcb's and matched LDR's (the hard part).  You supply the rest.  http://www.diyaudio.com/forums/showthread.php?s=&postid=1778975#post1778975

[JoshK]

I hadn't looked into the PSMLS or Pass as I haven't had need, I was just going by what I've gathered about them.

I am mostly certain your source and your amp will play nice with George's LDR. The only catch would be that you need to keep ICs fairly short for best results.  No 10 meter ICs.

[cporada]

Hi Josh
I'm using a 1M pair of MAC (Steve Hallick's company) Mystics from SACD to pre-amp and a 1M pair of MAC UltraSilver+ IC's from pre-amp to power amp. These should be okay; right?
Thanks so much for all your help and suggestions
Chris

[JoshK]

Hi Josh
I'm using a 1M pair of MAC (Steve Hallick's company) Mystics from SACD to pre-amp and a 1M pair of MAC UltraSilver+ IC's from pre-amp to power amp. These should be okay; right?
Thanks so much for all your help and suggestions
Chris

Seems fine to me.  I am not familiar with these particular cables though.  Unless they are super capacitive, the 1M length makes them congruent.

[cporada]

Hi Josh
Thanks! You should check out MAC:
http://www.myaudiocables.com/
They smoked everything I'd tried before, and the prices on Audiogon are great direct from MAC
Best
Chris

[Paul Hynes]

Hi Chris,

The impedance match with your equipment should be fine and the cables should not present any problems either. I am driving a heavy duty IXYS depletion mosfet with a 47K gate to ground resistor (my power amp output stage) directly from my Lightspeed with no matching issues and no loss of the audio high frequencies.

Regards
Paul

[cporada]

Hi Paul, Josh, and Dweekie
I just heard back from Marantz, the output impedance is 47 ohms on my SA15 SACD player.  Does that change anyone's thoughts on whether the Lightspeed and/or a TVC-based device would mate well with my system without any loss of drive and dynamics?
Thanks!
Chris

[Paul Hynes]

Hi Chris,

47 ohms drive impedance will work well with the Lightspeed so no change in recommendation.

Regards
Paul

[JoshK]

Yeah what Paul said.  Should be a breeze for the Marantz.

[georgehifi]

Hi guys, saw this thread when I Googled my Lightspeed Attenuator. Just to clear up the impedance matching issue.
For a good match in a system the Lightspeed Attenuator should see:
1 A CD player or Dac that has an output impedance of less than <1kohm (1000ohms)
2 The poweramp solid state or tube should have an input impedance of more than >47kohms (47K)

When these parameters are met you will have the deepest cleanest bass, most dynamic transients, most transparent sound stage and cleanest sweetest highs, you have heard.

For those of you who wish to build you own, I finally relent and give the details to DIY in this thread.

http://www.diyaudio.com/forums/showthread.php?s=85840c28cfe5fd93fde3bc2b751c8d7d&threadid=80194&perpage=25&pagenumber=1

And for those who wish pictures and more info on my production Lightspeed Attenuator please email me with your email address and I will send it to you.

Cheers George   

[cporada]

Hi George
So the Lightspeed should be a good match for my system even though my amp's input impedance is just above the recommended 47kohm?
I’d be using the LDR between a Marantz sa15 SACD player (2.1V output, output impedance is 47 ohms) and my 100 wpc solid state power amp (1.5V input sensitivity, 30db gain, 50kohm input impedance)
Thanks
Chris

[georgehifi]

Yep no problem Chris, the SA15 Marantz has a very good low impedance output stage.
We did a variable input poweramp test at our Audio Society, and the point where all the members started to hear a small detrimental effect was when we got down to 33k on the power amp, so 47k with a little headroom above the 33k is the right approx lowest figure to quote, anything above is this a bonus that may not be heard, I would say that if your source CD or DAC has a tube output stage then 100k may be just prefered over the 47k. 

Cheers George