Salas hotrodded blue DCB1 build

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#1,661
thanks Salas

R measures about 1.6 and 1.8 V
Vgs about 4 on one side and and 3.8 on the other
dc offset at .9 and -.7 mv

I thought that hotrod would get much warmer. The mills 3.3R are hot though

sounding great. bass is nice an tight.
using bib to power ldrs and arduino controller
thanks again
 
#1,664
OK... A couple observations and a question. I adjusted the current setting resistors to 3.9ohm from 10ohm and yes there is a subjective improvement. All of the good is a better. My system at this point sounds the best it ever has. Thank you all so much for helping me get here.

Now the question. I measure 1.33volts across one 3.9 and 1.72volts across the other. So there are different amounts of current. Across the 1ohm I get 5.78mv and 6.39mv. Should I simply adjust the 3.9 resistors to get even current, or is it more then that? The offset at the output is 1.4mv and 1.7 mv.

Thanks, Evan
 
#1,667
Well now I'm confused...I know, what's new..... I added resistance parallel to the 3.9 ohm resistor and did not get the expected result. The reading across the 1ohm resistor changes a lot less then I expected. I was able to get the current up to about 590 ma but that was with 2.7ohms in the set position. I quit while I was ahead and hooked the thing back up...Any thoughts?
Evan
 
#1,669
evanc said:
Well now I'm confused...I know, what's new..... I added resistance parallel to the 3.9 ohm resistor and did not get the expected result. The reading across the 1ohm resistor changes a lot less then I expected. I was able to get the current up to about 590 ma but that was with 2.7ohms in the set position. I quit while I was ahead and hooked the thing back up...Any thoughts?
Evan
Click to expand...

The power resistors you change value are to set/balance the main CCS currents between rails, have nothing to do with the indications on the 1 Ohm little resistors. Those are reflecting the IDSS differences of the Jfets serving the 5 LEDs strings and a little difference plays no role in the LEDs stability of forward drop.
 
#1,672
On which one rail you got the most drop on Rset? Use a bigger value there so to match the less drop one by Iccs=RsetVdrop/Rset. But 50mA differences won't change them transconductance when you are around the 0.5A mark. So don't strive for very good matching of CCS currents per rail.
 
#1,675
help

Hi,

I'm a relatively new guy with a new guy question.

My understanding is that the black Hypnotize board, offered by Tea-Bag, does not have volume control, and the hot rod supplies a higher current that supposedly increases the soundstage. Other than impedance matching, what do you feel is the sonic advantage of the B1 buffer?

I'm using a four channel MiniDSP with an on-board potentiometer, but I've read that it's non-optimal to attenuate the line-level volume in the digital domain because of SNR and "bit conversion accuracy" issues.

I would use two Hypnotize boards for all four channels. I don't require the Mezmerize board because I don't need more than one input source for each board. However, for reasons stated above, I would like to have some volume control in the analog domain, after the digital signal processing, and before I feed the signal to my power amplifiers... i.e. I need a good preamp with unity voltage gain and volume attenuation.

I could control volume from the DSP, and feed the Hypnotize board, but how would this be an advantage in regard to the audio quality? Isn't the B1 just one more potential noise source added to my audio chain? What is the advantage of the B1 without volume control?

Thanks,
Mason
 
#1,676
I will sum up why the DCzb1 is excellent. I recently built a new tube preamp and didnt have a 50k pot for it, so i just wired it up and used the dcb1 as a volume control. Today i added the pot to the tube pre and removed the dcb1. Removing the dcb1 changed the sound so little that i would have a hard time telling whether it was in the chain or not. For a passive pre, you cannot say more. :cheers: to Nelson and Salas.
 
#1,677
index.php


Just finished mine, but the leds are not giving me the complete lightshow. V- is ok, but the V+ is around 7vdc

Any idea where to start looking ?
 
#1,679
Usually one or more LEDS are put the wrong way around in the dim strings or are dead. A DMM in diode tester mode if able to light an LED, can be used to touch each and one up, as they are installed no problem, to see if some are dead due to too much iron. Else it can be some semis but one check at a time.
 
#1,680
Salas said:
Usually one or more LEDS are put the wrong way around in the dim strings or are dead. A DMM in diode tester mode if able to light an LED, can be used to touch each and one up, as the are installed no problem, to see if some are dead due to too much iron. Else it can be some semis but one check at a time.
Click to expand...

So.. if there is a dead led one place, the others will no light up ?
 
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