input / output impedance?
Hi folks-
I am hoping to use my Maximus Lightspeed after my Salas RIAA pre. The RIAA pre has an output impedance of ~30 ohms.
I tried looking through this very long thread but came up empty.
Can someone give me the average input and output impedances of the Lightspeed?
Thank you- Kent
Hi folks-
I am hoping to use my Maximus Lightspeed after my Salas RIAA pre. The RIAA pre has an output impedance of ~30 ohms.
I tried looking through this very long thread but came up empty.
Can someone give me the average input and output impedances of the Lightspeed?
Thank you- Kent
200 microV...that's basically the ripple noise spec of your 7805 regulator...it rides on and modulates your 5Vdc supply...do you see the LEDs flickering at 120Hz?
Definatly not!!! at .02mV of I'd like to see anyone see that! Beside the ldr's cannot follow it as well as they are not fast enough, think about it!!
30ohms output impedance is great to mate with the Lightspeed's 7-10kohm 'ish input impedance, just make sure your poweramp is 47Kohm or greater input impedance and you home and hose.
Cheers George
No worse than .2% at cd music playback levels, and that's 2HD which is pleasant to the ears if you can hear it over the speakers much higher distortions and tube amps in the percents.
Frequency response is dc-500khz as high as my test gear/leads will allow before it just starts to drop, I would say even higher, it will be the interconnects you use that will be the limiting factor in these speeds not the Lightspeed itself.
Cheers George
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A good plastic 10uf on the output of your riaa will get down to around -3db at 2hz with the Lightspeed.
Cheers George
No. In my opinion anyway. I think the LDRs get to screwy after around 22k to be good for replacing a 100k pot exactly. Now, probably no reason you have to use a 100k pot.
And yes, it smokes a stepped attenuator and a lot more. George has even been written up in Stereophile for the incredible sound from the Lightspeed.
Uriah
And yes, it smokes a stepped attenuator and a lot more. George has even been written up in Stereophile for the incredible sound from the Lightspeed.
Uriah
Udailey, thanks for the quick reply ! Also here is a link to the preamp I have and hope to up-grade ect.... http://www.diyaudio.com/forums/tubes-valves/184023-cary-aes-ae3-linestage-help-needed.html
Can the Light-speed be configured to replace a 100K pot in a tube preamp ? If so how, and are there kits available ?
........and the good news is that with a 6-7k LDR shunted from grid to ground, your tube preamp will be quieter than with the 100k pot. Just be sure to install a large value resistor from grid to ground (assuming your preamp is grounded grid) so that the grid leak function is maintained when the LDRs are off. 1M is probably an absolute maximum, 470k is a safe bet.
Stuart
WOW. Thank you.
Just want to thank George and Uriah. The idea is fantastic and building attenuator from The Lighter Note kit was fun even for the first-timer like me. The sound improvement comparing to the pot in Benchmark DAC is just unbelievable. I must say I did a little tweaking: I put LDRs in separate boxes that can be attached directly to the power amp inputs.
As I mentioned, I am noob therefore my question: When I power off the attenuator the volume goes up. I checked resistance on RCA connectors with attenuator powered off. Between RCA center connectors it is 192K and between outer sides is 0R. No connection between inner and outer sides. Did I something wrong or this is quite normal
Just want to thank George and Uriah. The idea is fantastic and building attenuator from The Lighter Note kit was fun even for the first-timer like me. The sound improvement comparing to the pot in Benchmark DAC is just unbelievable. I must say I did a little tweaking: I put LDRs in separate boxes that can be attached directly to the power amp inputs.
As I mentioned, I am noob therefore my question: When I power off the attenuator the volume goes up. I checked resistance on RCA connectors with attenuator powered off. Between RCA center connectors it is 192K and between outer sides is 0R. No connection between inner and outer sides. Did I something wrong or this is quite normal
When I power off the attenuator the volume goes up. I checked resistance on RCA connectors with attenuator powered off. Between RCA center connectors it is 192K and between outer sides is 0R. No connection between inner and outer sides. Did I something wrong or this is quite normal[/QUOTE]
I believe its something to do with the LDR's going to a high impedance and someone does explain it [ Paul Hynes I think ] and its buried somewhere in this post. Why do you turn off the attenuator before the power amp?
[/QUOTE]I believe its something to do with the LDR's going to a high impedance and someone does explain it [ Paul Hynes I think ] and its buried somewhere in this post. Why do you turn off the attenuator before the power amp?
Glad you guys are enjoying it. Even though this is a LDR thread and I am heavily involved in it, lets please keep it to George's circuit. If you have Lighter Note questions please feel free to email me. I sincerely enjoy helping guys out and its no bother at all if I have to answer the same question a bunch of times.
Your question about volume is relevant to George's circuit as well, though.
What is happening is that the series LDRs are using an extremely small amount of power and the shunt LDRs are using relatively higher amount of power. When you turn the circuit off the amount of power available for a short time to the LDRs quickly grows to much less than the shunts need to stay at the resistance they are at. The series need near nothing at this point to keep their resistance so they increase in resistance much slower, relatively, than the shunts. Since this attenuator is a voltage divider... when the shunts increase in resistance faster than the series then the volume increases.
Just turn off the LDR attenuator last or just leave it on. Both circuits use a tiny tiny amount of power. If you want to only use less than a mA when not listening then just turn to mid volume and leave it there. You dont need to turn them off. The nice thing about leaving them on is that there will be no surprises when you turn on the amp.
Uriah
Your question about volume is relevant to George's circuit as well, though.
What is happening is that the series LDRs are using an extremely small amount of power and the shunt LDRs are using relatively higher amount of power. When you turn the circuit off the amount of power available for a short time to the LDRs quickly grows to much less than the shunts need to stay at the resistance they are at. The series need near nothing at this point to keep their resistance so they increase in resistance much slower, relatively, than the shunts. Since this attenuator is a voltage divider... when the shunts increase in resistance faster than the series then the volume increases.
Just turn off the LDR attenuator last or just leave it on. Both circuits use a tiny tiny amount of power. If you want to only use less than a mA when not listening then just turn to mid volume and leave it there. You dont need to turn them off. The nice thing about leaving them on is that there will be no surprises when you turn on the amp.
Uriah
RE: Volume level when powered off.
Thank you all very much for the answer. I was just concerned whether I did everything according to the design. For me this is not a big problem because my switch in attenuator also turns on my power amps.So unless someone pulls out the power cable from attenuator while playing music or resistance raise in LDR's did not catch up with the time delays for the amps relays everything should be OK. Anyways, I am very exited with the results and just wanted to thank you again.
Thank you all very much for the answer. I was just concerned whether I did everything according to the design. For me this is not a big problem because my switch in attenuator also turns on my power amps.So unless someone pulls out the power cable from attenuator while playing music
or resistance raise in LDR's did not catch up with the time delays for the amps relays everything should be OK. Anyways, I am very exited with the results and just wanted to thank you again.Just want to thank George and Uriah. The idea is fantastic and building attenuator from The Lighter Note kit was fun even for the first-timer like me. The sound improvement comparing to the pot in Benchmark DAC is just unbelievable. I must say I did a little tweaking: I put LDRs in separate boxes that can be attached directly to the power amp inputs.
As I mentioned, I am noob therefore my question: When I power off the attenuator the volume goes up. I checked resistance on RCA connectors with attenuator powered off. Between RCA center connectors it is 192K and between outer sides is 0R. No connection between inner and outer sides. Did I something wrong or this is quite normal
I had heard the LDR against the Benchmark HDR, like you say, it is simply unbelievable - better dynamics/transient attack & transparency.