Salas hotrodded blue DCB1 build - Page 259 - diyAudio
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Old 15th January 2013, 08:35 AM   #2581
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Have just tried the lightspeed in dcb1. Earlier in my AN linestage I tried
Alps Blue -> noble pot -> tkd cp2511 (all 100k dual logs)

The TKD was best, then noble and so alps blue.
The ldr volume control was much better than these (with regards to soundquality) but the volume tracking with the AN preamp was a bitch. Just perfect with the dcb1.
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Old 15th January 2013, 08:51 AM   #2582
kroyin is offline kroyin  India
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Quote:
Originally Posted by Salas View Post
And the conclusion is that with optivol and DCB1 there is better synergy and you ended up there as your best combination? Correct?
Correct, it is better than all possible B1 combos that I played with.

That said I'm yet to test it with pots (no mono pot below 20k with me right now)
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Old 15th January 2013, 01:42 PM   #2583
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While the optivol is inspired by and similar to the Lightspeed, it is NOT the Lightspeed. The LSA is minimalist/passive design without buffer. The power supply is only there to supply the LEDs, which are not in the signal chain. The optivol has a buffer, so you are listening to that as well.

In my system, the (passive) LSA lacked drive and volume and the highs were missing, even with 1.5M ultra low capacitance cables. However, the LSA is so highly regarded elsewhere in DIYA that I want to stick with it. Hence, I will add the DCB1 buffer, which I am confident is better than the optivol's buffer.

There are 5 commercial variations of the second generation Lightspeed that I know of. George (inventor) will say that all 4 clones are inferior to his.
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Old 16th January 2013, 07:59 PM   #2584
Siberia is online now Siberia  Lithuania
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Default sad news here

It's been a month since my dcb1 was finally housed in an appropriate box. When I passed to change the track today, I've inhaled a light warm smell of plastic coming from inside the box. After opening it, I found a tripplet of mosFET Vgs setting leds down. It's on a positive rail with a heatsink running blimey hot. Does that mean one of my Mosfets are down? Curiously, the music was still playing and the voltages measured OK.
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Old 16th January 2013, 08:53 PM   #2585
Siberia is online now Siberia  Lithuania
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Oh, and there was small mechanical noise coming from one of pcb mounteds componets too.
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Old 16th January 2013, 09:50 PM   #2586
Salas is online now Salas  Greece
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Check the leds first by trying to light them up one by one fast with a 9V battery as they sit there with the power down. If they all light up, then it should be the CCS Mosfet or the setting resistor.
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Old 17th January 2013, 08:54 PM   #2587
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Fixed by replacing a faulty LED. Thank you, again.
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Old 18th January 2013, 01:40 PM   #2588
kroyin is offline kroyin  India
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Well I have a question

I have a 50va 15-0-15 rcore

Using a 10r mosfet source resistor gives 1.2 odd volts across the resistor.
This translates to 120mA,where did the rest go?

Again paralleling 2 10r gives 1 V across the resistor, so 100mA while it should have been around 300mA

There must be something wrong with my understanding
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Old 18th January 2013, 02:03 PM   #2589
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Paralleling 2 x 10R gives you 5R.

I=E/R so I=1/5 I is now 200mA.
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Old 18th January 2013, 02:06 PM   #2590
kroyin is offline kroyin  India
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I am embarrassed...but any idea what is stealing the amps

Last edited by kroyin; 18th January 2013 at 02:12 PM.
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