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Old 16th August 2012, 01:28 PM   #4801
AndrewT is offline AndrewT  Scotland
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Every Member that reads this Thread is aware of the input impedance of the Lightspeed.
We ALL know it is similar to a 10k to 20k conventional vol pot.

I would be tempted to try a 10uF to 15uF as the coupling cap feeding the Lightspeed.
That would give me a turn over frequency about one octave below the 90ms I use at the Power Amplifier/s
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Old 16th August 2012, 08:29 PM   #4802
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What can i say.... It must be me then....

But the lightspeed is certainly not for everyone then, unfortunately. Many high end equipment with a 2.2uf film cap at their output are not suited for use with the lightspeed as preamp.
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Old 16th August 2012, 10:30 PM   #4803
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Most are aware, as it's been mentioned many times over in previous post.
That is why tube output sources of the higher output impedance variety of over 3k are not getting the best output drive, they work and sound fine but are not giving 100% of what can be achieved.

Cheers George
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Old 17th August 2012, 07:06 AM   #4804
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Quote:
Originally Posted by studiostevus View Post
What can i say.... It must be me then....

Many high end equipment with a 2.2uf film cap at their output are not suited for use with the lightspeed as preamp.
Yes also the same source equipment your quoting with 2.2uf caps in their rear ends are by your reckoning not suited for some of these either as many also have 10k input impedances. But 2.2uf into 10k will give a -3db point of 7hz which is ok by me. A 4.7uf will take this down another octave to around 3hz -3db. A 10uf to -1.5hz -3db.

Class D amps
Chip Amps
Many of the Pass Lab Amps.
And the list goes on!

Cheers George
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Last edited by georgehifi; 17th August 2012 at 07:11 AM.
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Old 11th September 2012, 09:59 PM   #4805
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My Lightspeed has arrived safe and sound although there is a big hole on the box ( bad post office delivery). Luckily, there is no damage inside at all.

I have no clue about my tube power amp's sentative input. But I think it is sentative enough for Lightspeed Att.

Follow the instruction, I left it on with the vol at 12 o'clock position for a while. My God, I accidentally pressed play button on the remote control ( when the vol at 12:00), the sound is so loud. Lucky, there is no damage to the power amps and speakers

However, the sound is still abit loud ( just abit ) when the vol is fully down to Zero position. At fully down position, it is suitable for listening late at night. Some thing wrong here. I think it is my system:

My CD player with tube output is a bit higher than usual ( Marantz CD48 mod by TenAudio with tube output). My tube power amp is so sentative ( WAD K5881 mono block)

However, the first thing I reckon about LighSpeed Att is transparent. I need more time to experience it

Please tell me how long does it take for burning time? Do I need burning time? Thanks
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Old 12th September 2012, 12:22 AM   #4806
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Quote:
Originally Posted by Pass lover View Post
My Lightspeed has arrived safe and sound although there is a big hole on the box ( bad post office delivery). Luckily, there is no damage inside at all.That was lucky

I have no clue about my tube power amp's sentative input. But I think it is sentative enough for Lightspeed Att.All tube amps I've seen have good high input impedance usually more than >47Kohm

Follow the instruction, I left it on with the vol at 12 o'clock position for a while. My God, I accidentally pressed play button on the remote control ( when the vol at 12:00), the sound is so loud. Lucky, there is no damage to the power amps and speakers

However, the sound is still abit loud ( just abit ) when the vol is fully down to Zero position. At fully down position, it is suitable for listening late at night. Some thing wrong here. I think it is my system:This is normal as the Lightspeed Attenuator can never go to complete zero

My CD player with tube output is a bit higher than usual ( Marantz CD48 mod by TenAudio with tube output).This is why you are at half or under for normal listening, and that your amp is sensitive as well, no problem there. As you can see there is no need for a gain stage at all. My tube power amp is so sentative ( WAD K5881 mono block)

However, the first thing I reckon about LighSpeed Att is transparent. I need more time to experience it. Glad your hearing the benifits already of no contacts and electronics in the siganal path. You will also experience greater dynamic range with more body to everything in a less squeezed out in your face way

Please tell me how long does it take for burning time? Do I need burning time? Thanks
Usually not much a day or so. Cheers George
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Old 12th September 2012, 09:09 AM   #4807
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If your volume is always at the bottom and sometimes you want even less, then you need to change the gain in your system. It's not the volume pot that is wrong, nor is it the volume pot that is causing the problem.
The "problem" is excessive system gain.

read
What is Gain Structure?
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Old 30th September 2012, 04:22 PM   #4808
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Default What is the latest mode ??

I finished my version a few years back and lately I've been trying to do the follow up and see what kind of up-grade I could do to my lightspeed. Wow the thread is really active and long. I'm too far falling behind. Can anyone tell me what is the latest mode for this wonderful control ?? Thanks

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Old 30th September 2012, 10:19 PM   #4809
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Still series ldr with shunt ldr to ground. Powering by 12v rechargeable Lithium battery seem to be a popular second option by my customers, but it's so close to the standard wall wart way of powering it doesn't seem worth the hassle
I have attached the stereo version and also the dual mono version.
And a diy ldr matcher that can be bought at electronic shops, only costs about $10, so you can do your own quad ldr matching. It's what I used when I first started out making the Lightspeed Attenuator.

PS: For all the owners of a Lightspeed Attenuator, you will again be pleased to know that it has once again been listed in the Stereophile Recommended Components (October 2012) list with highest value $$$ rating.

Cheers George
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File Type: jpg LDR tester.jpg (60.5 KB, 332 views)
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Old 1st October 2012, 02:00 AM   #4810
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Thanks George,

PS: For all the owners of a Lightspeed Attenuator, you will again be pleased to know that it has once again been listed in the Stereophile Recommended Components (October 2012) list with highest value $$$ rating.

It is to confirm your hard work paid off.

It's good to know I don't have to up-grade anything after so many years. I really would love to try the battery, but give up after seeing your reply.
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