Lightspeed Attenuator a new passive preamp - Page 480

AndrewT · 12th August 2012, 11:34 AM

I recommend double filtering of the RF that flies around the modern home.
1. At the input to the power amp.
2. at the input to the box/screen that contains the power amp.

For 1. I use a 0.68us time constant, but any value from 0.3us to 1.5us are commonly used.
For 2. I use a 47pF directly across hot and return on the RCA input socket.

You may find that one or the other is adequate. But with all the radio transmitters around the modern home and in your neighbours', then I believe that more RF attenuation is better than audio contamination.

portreathbeach · 12th August 2012, 11:48 AM

Thanks. I'll have to experiment

Pass lover · 13th August 2012, 12:21 AM

Hi

I am not upto date with the threats

Does anyone know if George did make 7.1 pre amp for home theater use? Can I order from him?

The set up is for connecting Oppo 95 7.1 analogue output to the power amp.

Thanks

georgehifi · 13th August 2012, 12:38 AM

Quote:

Originally Posted by Pass lover

Hi

Does anyone know if George did make 7.1 pre amp for home theater use? Can I order from him?

Thanks

No sorry, only two channel for stereo use, a 7.1 would be a nightmare to do and get right, if at all. better off using one of these CT2 8 channel ones.
DACT audio attenuators

Cheers George

thisisvv · 14th August 2012, 02:50 AM

may be this is asked many times, how hard is to make this for a guy who hasnt soldered in a decade...

also any place where i can get this

studiostevus · 16th August 2012, 08:50 AM

Quote:

Originally Posted by georgehifi

If the stage after the Lightspeed is 100k input impedance then the input impedance of the Lightspeed is between 10k-15k,
Here is the Graph that Tom Gootee plotted for the input impedance of the Lightspeed Attenuator (how I make them) for three different poweramp input impedances.
Thanks again for the graphs Tom!
Lightspeed Attenuator a new passive preamp

Cheers George

I have been trying to get my head around this but can't figure it out....
I am looking to replace the output capacitor of my dac with a better one, and I am trying to pick a value for this cap (as low as possible is best, as I want to use something good/expensive).

My setup:

Dac(tube output) --> Lightspeed --> Aikido LV preamp --> Pass F5

Can someone help me to select the right size output cap for the dac?
I don't want to use another buffer stage tbh.

georgehifi · 16th August 2012, 09:42 AM

4.7uf will be plenty with the combined resistance of the Lightspeed and input impedace of the Aikido.

Cheers George

studiostevus · 16th August 2012, 10:26 AM

wow... that seems awfully high...

Am I wrong to assume that the impedance of the combined Aikido+Lightspeed should be well above 100K ?

georgehifi · 16th August 2012, 10:37 AM

It will be around 10k.

Cheers George

studiostevus · 16th August 2012, 10:49 AM

Didn't expect that....!

I would be suprised if the others who have build and are using the lightspeed are aware of this and have adapted their source equipment to suit this!

12th August 2012, 11:48 AM	#4792
portreathbeach diyAudio Member Join Date: Jan 2010 Location: Cornwall	Thanks. I'll have to experiment __________________ Another project of mine: (a very big one at that!) http://www.mp3car.com/vbulletin/show...5-pimping.html

16th August 2012, 09:42 AM	#4797
georgehifi diyAudio Member Join Date: Sep 2003 Location: Manly Australia (Jewel of the Pacific)	4.7uf will be plenty with the combined resistance of the Lightspeed and input impedace of the Aikido. Cheers George __________________ Avatar : Production Lightspeed Attenuator www.lightspeedattenuator.com

16th August 2012, 10:37 AM	#4799
georgehifi diyAudio Member Join Date: Sep 2003 Location: Manly Australia (Jewel of the Pacific)	It will be around 10k. Cheers George __________________ Avatar : Production Lightspeed Attenuator www.lightspeedattenuator.com

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12th August 2012, 11:34 AM	#4791
AndrewT diyAudio Member Join Date: Jul 2004 Location: Scottish Borders	I recommend double filtering of the RF that flies around the modern home. 1. At the input to the power amp. 2. at the input to the box/screen that contains the power amp. For 1. I use a 0.68us time constant, but any value from 0.3us to 1.5us are commonly used. For 2. I use a 47pF directly across hot and return on the RCA input socket. You may find that one or the other is adequate. But with all the radio transmitters around the modern home and in your neighbours', then I believe that more RF attenuation is better than audio contamination.

13th August 2012, 12:21 AM	#4793
Pass lover diyAudio Member Join Date: Dec 2006	Hi I am not upto date with the threats Does anyone know if George did make 7.1 pre amp for home theater use? Can I order from him? The set up is for connecting Oppo 95 7.1 analogue output to the power amp. Thanks

14th August 2012, 02:50 AM	#4795
thisisvv diyAudio Member Join Date: Apr 2012	may be this is asked many times, how hard is to make this for a guy who hasnt soldered in a decade... also any place where i can get this

16th August 2012, 10:26 AM	#4798
studiostevus diyAudio Member Join Date: Oct 2009 Location: Brunei	wow... that seems awfully high... Am I wrong to assume that the impedance of the combined Aikido+Lightspeed should be well above 100K ?

16th August 2012, 10:49 AM	#4800
studiostevus diyAudio Member Join Date: Oct 2009 Location: Brunei	Didn't expect that....! I would be suprised if the others who have build and are using the lightspeed are aware of this and have adapted their source equipment to suit this!