Mezmerize B1 Buffer Preamp

No BRexit for us!!

Are you in the EU?
I have some lsk170 a grade
see swap meet.
Although the matched pairs I have to sell should not be wasted in a DCB1. I have turned away many potential customers who wanted my matched pairs for DCB1.

I live in 'The People's Republic Of Cork' which is a local joke for Irish folk.

I'm Happy for you that you have 'A' matched pairs to spare, but Sad that you think they are wasted on me ;-)
You wouldn't have a wee pile of unmatched ones that You could be persuaded
(ie paid) to put 4 together that you would think 'Good Enough for a DCB1' would you??
Thanks,
Steve
 
Haha!!
"many here who do not live where they belong/grew up/born/passport."

Said like a true Scotsman - I'm from Wales originally - (hence my eddress - stevewales0)
There are many there, as in Ireland and Scotland who emphasis the 'Belong'.
Anyway -- I know this isn't a 'correct' subject for this forum and I meant no offence, just my sense of humour responding to AndrewT's sometimes Dour manner ;-)
Peace be to all.
(Thanks Andrew for the message)
 
diyAudio Chief Moderator
Joined 2002
Paid Member
From what I remember after I had followed many hundreds of members builds in the dcb1 threads there were rather enough bad led occasions indeed. Some 3mm individual Leds can prove unreliable after some hours of use especially in a hot environment and certainly sensitive to high temp prolonged soldering.

About a single led remaining lit I don't remember. Talking for one in the strings of five or in the strings of three? Others may comment on that.
 
Mezmerize B1

Thanks,
i suspected poor quality leds but its true you are solving pretty close to them.
The single lit is the one working of three on positive side, curiously enough the voltage is spot on with 0,5 higher on negative side and i cant hear it affect the sound in any way wich are very clear and detail, FAR better than the original.
 
Hey all,

I have downsized houses and have gone from a rather large(for my area) 1300sqft house down to 900sqft.

As I continue to shrink my foot print and minimize I am going from surround sound to a 2.1 setup and part of that is going to be dropping from an AVR to small separates.

I am really interested in going to a DCB1 and some Hypex amps/active speakers

Can the DCB1 be configured to have a sub out?

I am going to use my Bottlehead Quickie right now but would like to have something without the microphonics.
 
Bad luck with LED's

Hi, guys. I'm finally getting around to building my DCB1, and am having trouble with the LED sourcing similar to what was reported by user nkalogridis earlier.

I purchased the 593-VAOL-3HCE4 VCC 1.8V 20mA LED's. I am measuring them using a 9.71VDC battery, and have tried them with both a 1K and 1.5K resistor. I am measuring 1.91V (7.8 mA) with the 1K resistor. I am measuring 1.89V (5.2 mA) with the 1.5K resistor. Earlier, I had checked them with a 460 ohm resistor to get closer to their rated current, and they measured 2.01 V. So, clearly, they are not 1.8 Vf LED's as advertised.

Can these be used? I think not. If not, can I get some part number recommendations from those who have had better luck hitting the 1.8V nominal target. I don't mind waiting a week to get this right.

Thanks,

Andy
 
Hi Andy, I had some bad luck with the LED's , but the one that actually were almost spot on in the 1.8V were these OSNR3134A, on a previous post in the build thread I was getting these voltages across the LED's :
- over the positive (9240 MOSFET) side 3 LED's I have 5.42V ;
- over the negative (240 MOSFET) side 3 LED's I have 5.44V ;
- on the positive side 5 LED's I have 8.90V and on the negative 8.84V (Here I could play with one or two LED that I have measured with 100mV higher the the red ones to get close to 9V)
- on the test point, the output of the reg. (the 3 little pads behind the 10ohm resistors ) I have 9.52V on the positive side and 9.48V on the negative.
Apparently these were ok values to power up the buffer and have it functional according to Salas and it does work fine. You could do a mix and match to get very close to the required value (I could of done that on the 5LED's sides but removing one or two of them and re soldering another to get what I want implies potential damages to the PCB as one member faced in his build).
As a side note try and solder them a bit higher from the board this way the internals while soldering wont get to hot, I soldered mine at about 5mm height.
Thanks,
Florin
 
Hi, guys. I'm finally getting around to building my DCB1, and am having trouble with the LED sourcing similar to what was reported by user nkalogridis earlier.

I purchased the 593-VAOL-3HCE4 VCC 1.8V 20mA LED's. I am measuring them using a 9.71VDC battery, and have tried them with both a 1K and 1.5K resistor. I am measuring 1.91V (7.8 mA) with the 1K resistor. I am measuring 1.89V (5.2 mA) with the 1.5K resistor. Earlier, I had checked them with a 460 ohm resistor to get closer to their rated current, and they measured 2.01 V. So, clearly, they are not 1.8 Vf LED's as advertised.

Can these be used? I think not. If not, can I get some part number recommendations from those who have had better luck hitting the 1.8V nominal target. I don't mind waiting a week to get this right.

Thanks,

Andy
You are misunderstanding the specifications.
The 20mA figure is the maximum current. Any higher and you are likely to damage them.

If they are lowish light output then a current from 2mA to 5mA would be about right for long life and reasonable dynamic impedance and quantity of light.
High light output could need as low as 0.5mA to 3mA the same light.

Try a 4k7 resistor and a 10k resistor and measure the Vf.

You can use the CURRENT as the trimmer to set the Vref you require from the series string.
 
J111 can run high mA through itself, the error amplifier BJT, and the LEDS, compromising long term reliability. All FETS are used at IDSS in this circuit. If one must use some J series better use J112. Its not a different FET for noise and gm while the IDSS is moderate vs J111.

*Any gm any parasitic capacitance and any noise spec for the rest of FETS than those six can change the power supply performance to a degree nonetheless.



Does this mean, that J111's could be used ...if yes, what Idss values could be suitable