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Old 25th May 2010, 01:26 AM   #1471
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Originally Posted by Salas View Post
I like that slim chassis. Is that chassis not ready made, but DIY from aluminum panels? Congratulations for the build, you can organize it later inside, most important is that you got the sound you liked. What is the rest of the system made of?
Thanks to Salas for the tremendous help rendered during the build!!

Got it from a local store, think they CNC-ed a a few sets for hobbyists. But yeah I guess it's DIY from some aluminium panels.

The DCB1 is currently driving a Rythmik sub and a TDA2020 amp powering Coral Beta 8s. IMHO, sound is superb to me, even the wife says so!
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Old 25th May 2010, 01:28 AM   #1472
Salas is offline Salas  Greece
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Old 26th May 2010, 03:52 AM   #1473
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Here is my take on the B1:

Click the image to open in full size.

Yes,it sounds nice..
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Old 26th May 2010, 08:14 AM   #1474
Salas is offline Salas  Greece
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Thanks Ryssen. You are the one that started the GB thread we should remember as well. Using no pot? An interface? Weird transformer.
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Old 26th May 2010, 08:56 AM   #1475
Ryssen is offline Ryssen  Sweden
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The trafo is an upside down toroid ment for pcbs..
I am going tu use the B1 between my CS4398 DAC with trafo output and the F5,and the volume control is done digital in my digital mixer.Since there was some strange problem with heat rise in F5 if I connect the DAC directly to it,I will try with the B1 inbetween.
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Old 26th May 2010, 10:35 PM   #1476
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Originally Posted by regiregi22 View Post
Macronaut, you could connect it without having a pot in front of it, If you have e volume controls in your source (like a PC audio card)
regiregi22, Thanks for the confirmation.

Since Memorial day weekend gives me some time to try the DCB1 with Lightspeed control I thought I would ask how some of you might be doing this. I have done some thread searches but have not found any answers yet. Ya, I know, I probably didn't use the right search terms. Anyway, it appears that the input impedance for the circuit should be a little less than 220k ohms. I have read that the Lightspeed control works best with impedances greater than 50k ohms so I do not think there is going to be a problem. I have gutted a CD player case and am ready to start putting this together.

Am I seeing the circuit correctly? I am assuming the gate impedance of the JFET's is far higher than the 220k resistor across the input. Or would it be better to use an adjustable input for balance or trimming purposes? I will be using a CD player as a source.
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Old 26th May 2010, 11:00 PM   #1477
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I'm not an expert but I do use the Lightspeed in my DCB1. The circuit is designed for a pot in the 15k - 25k range. Your LS will be a bit less than this which is fine. The idea is to maintain a 1:10 ratio, i.e. 22k pot:220k resistor on gate, but I don't think this is critical, just a guideline. In fact, I do something a bit different than most, and drive two DCB1's with the LS, works fine. CD player into the LS should be OK, output impedance on those typically quite low.
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Old 26th May 2010, 11:18 PM   #1478
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Macronaut, I would consider using a little trimpot in there if you really want to tune in to optimal sound.
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Old 26th May 2010, 11:19 PM   #1479
Salas is offline Salas  Greece
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What happens is we want to have good extension much beyond audio so the impedance that drives the high gate capacitance of the 2SK170 does not slow down square wave performance. Up to 20-22K pot I found it subjectively not much detectable and it was high enough not to challenge most of the sources I could think of as well. If sources are very low impedance with good drive, then 10K pots or less are even ''faster'' driving the gates.
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Old 27th May 2010, 01:35 AM   #1480
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William 2001, Tea-Bag, Salas, Thank you. Gives me a couple of things I had not thought of.
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