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
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
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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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
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
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
http://www.diyaudio.com/forums/diyaudio-com-articles/186018-what-gain-structure.html
The "problem" is excessive system gain.
read
http://www.diyaudio.com/forums/diyaudio-com-articles/186018-what-gain-structure.html
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
Albert
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
Albert
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 $$$ rating.
Cheers George
I have attached the stereo version and also the dual mono version.
And a diy ldr matcher that can be bought at electronic shops, only costs about $10, so you can do your own quad ldr matching. It's what I used when I first started out making the Lightspeed Attenuator.
PS: For all the owners of a Lightspeed Attenuator, you will again be pleased to know that it has once again been listed in the Stereophile Recommended Components (October 2012) list with highest value $$$ rating.
Cheers George
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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 $$$ rating.
It is to confirm your hard work paid off.
It's good to know I don't have to up-grade anything after so many years. I really would love to try the battery, but give up after seeing your reply.
Albert
PS: For all the owners of a Lightspeed Attenuator, you will again be pleased to know that it has once again been listed in the Stereophile Recommended Components (October 2012) list with highest value $$$ 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.
Albert
The second one up after 3 years
I finished another one for my second system on my bedroom. Nothing special but surprisingly found couple pairs the specs are really close. This one I go with the original design with dual 100k pot. Measure extremely good and didn't try on sound yet. Will report after serious listening.
I finished another one for my second system on my bedroom. Nothing special but surprisingly found couple pairs the specs are really close. This one I go with the original design with dual 100k pot. Measure extremely good and didn't try on sound yet. Will report after serious listening.
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Hi Albert, you must have had your scope switched on AC coupling and not DC, or your source/generator is not dc coupled, as your square waves from 20hz to 100hz should have looked just like the 1khz to 20khz ones, absouletly square.
And I would say the slight rounding of the 100khz wave is most probably the scope probes capacitance.
Cheers George
And I would say the slight rounding of the 100khz wave is most probably the scope probes capacitance.
Cheers George
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I have my machines checked and found this is the problem of the signal generator which gives the same wave form as posted. So I presume the wave form on the lower octaves should be all square.
Time to buy another S/G, or does anyone knows how to repair the machine ??
Albert
Dear Albert,
It's the impedance of the lightsppeed attenuator is so low that the Sig Gen output impedance is a bit high to provide a perfect square waveform. The CD player or DAC output should have much lower impedance that the low frequency drive shouldn't be problem at all. Give it a try and try it in your system.
Johnny
It's the impedance of the lightsppeed attenuator is so low that the Sig Gen output impedance is a bit high to provide a perfect square waveform. The CD player or DAC output should have much lower impedance that the low frequency drive shouldn't be problem at all. Give it a try and try it in your system.
Johnny
Or it's (6DJ8) output series coupling cap is too small, it should be in the order of 10uf to give a -3db down point in the order of 2hz
Cheers George
He was using a signal generator for those LF square waves anyway and it should be fine driving into the 7k-10k load of the Lightspeed unless it's faulty or has too small coupling cap, or the scope was not switched to dc coupled, the dac is something else again.
This is why I never advocate the use of tube output dacs or cdp that have pathetic high output impedance, some are ok like the (SLCF) super linear cathode follower that's 100ohm output, but there are many that have up to 7k output impedance that have trouble driving may preamps passive or active.
Cheers George
This is why I never advocate the use of tube output dacs or cdp that have pathetic high output impedance, some are ok like the (SLCF) super linear cathode follower that's 100ohm output, but there are many that have up to 7k output impedance that have trouble driving may preamps passive or active.
Cheers George