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Old 13th August 2013, 04:44 PM   #5141
Eric is offline Eric  United States
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Thanks for the recommendations, George! My plan was to try my DAC and DCB1 directly into the F4 without any additional gain to see what I got in terms of power output... I'll work up another circuit with just the LDRs for the front end of the F4.

This is just too much fun!
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Old 29th September 2013, 08:27 AM   #5142
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Thanks for sharing the design of this George.

I've gotten the itch to solder something and I hear that the pre on my new(ish) C370 is slightly weaker than the power section, so I'm going to build myself one of these.

I'm a little concerned about the impedances being out of spec. I may have to look at building a buffer but I wondered if anyone could advise on whether it's worth a try without or is guaranteed to need it.

Input will be a Cambridge 740C - <50ohm
Power will be NAD C370 - 20kOhm

I'm thinking perhaps having a low impedance on the input might compensate a bit for the low on the out?

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Old 29th September 2013, 08:56 AM   #5143
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I'm a little concerned about the impedances being out of spec.

I use the Lightspeed circuit to drive bi-amped Quad 303s which have an input impedance of 20K per amp, 10K per channel. The system probably has no right to work but it does, rather well in fact.
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Old 29th September 2013, 11:18 AM   #5144
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The combined load say of power amp @ 20k and Lightspeed Attenuator @10k is what the source will see. If the source has a nice low output impedance that has say 50ohms output impedance, it can take a load of 6.66k no problem.

Cheers George
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Old 29th September 2013, 01:18 PM   #5145
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Oh excellent. Thanks both for getting back to me so quickly. Ordering the bits now....
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Old 30th September 2013, 06:14 AM   #5146
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Just thought you DIY'ers and owners of the Lightspeed Attenuator would like to know, that it has made it again into 2013 Octobers Stereophile Recommended Components, with the highest $$$ value rating once more.

Cheers George
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Old 1st October 2013, 02:03 PM   #5147
wlowes is offline wlowes  Canada
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Quote:
Originally Posted by georgehifi View Post
Just thought you DIY'ers and owners of the Lightspeed Attenuator would like to know, that it has made it again into 2013 Octobers Stereophile Recommended Components, with the highest $$$ value rating once more.

Cheers George
I had actually seen this on the week end. Congratulations again George and thank you for allowing the DIY crowd to gain access to this. We are, thanks to you enjoying sound that many reviewers compare against multi k$ boutique offerings.

I went looking for the 2010 review in Stereophile and could not find it. Do you have a link to that article?
walter
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Old 1st October 2013, 06:42 PM   #5148
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Default Lightspeed attenuator for LM3875

Anyone using the lightspeed with a LM3875 chip amp? I'd like to know how well it matches up with it.

Thanks.
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Old 1st October 2013, 07:26 PM   #5149
Eric is offline Eric  United States
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Congrats to you, George! This must be a wonderful feeling of pride and accomplishment for you! Thank you for generously sharing your work with us - I for one appreciate your dedication to the community and the gift you have bestowed upon us!
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Old 1st October 2013, 08:47 PM   #5150
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Congrats!
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