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-   -   Salas hotrodded blue DCB1 build (http://www.diyaudio.com/forums/analog-line-level/171715-salas-hotrodded-blue-dcb1-build.html)

wendell c 12th August 2010 01:54 AM

Tea-Bag gave me a ref for the relay from mouser but they charging $20 ship if min not met. I cross referenced the part on DigiKey but not avail, will this work 255-1002-5-ND

Digi-Key - 255-1002-5-ND (Manufacturer - TQ2-12V)

ppcblaster 12th August 2010 02:45 PM

School
 
1 Attachment(s)
Pleas explain the purpose of the LED's.

Are they used as a resistor?

If not matched, what is the consequence?

LucasAdamson 12th August 2010 03:55 PM

Received first of 3 boards this morning. Lovely! Many thanks.

I am going to use it for RIAA supply at 27v. I will only need the + rail. How do I isolate the other rail regarding the diodes and power supply caps? Will I need only 2xMUR820, or is it still as I assume x4 I need? Presumably I only need x2 of the x4 caps. Will I need to add a jumper somewhere to link it up?

What transformer is recommended for a 27v single rail device with this reg please?

Many thanks
Lucas

Salas 12th August 2010 04:30 PM

Quote:

Originally Posted by ppcblaster (Post 2270576)
Pleas explain the purpose of the LED's.

Are they used as a resistor?

If not matched, what is the consequence?

They are the active low noise voltage reference. If not matched, small assymetry in +/- Vout.

Salas 12th August 2010 04:31 PM

Quote:

Originally Posted by LucasAdamson (Post 2270635)
Received first of 3 boards this morning. Lovely! Many thanks.

I am going to use it for RIAA supply at 27v. I will only need the + rail. How do I isolate the other rail regarding the diodes and power supply caps? Will I need only 2xMUR820, or is it still as I assume x4 I need? Presumably I only need x2 of the x4 caps. Will I need to add a jumper somewhere to link it up?

What transformer is recommended for a 27v single rail device with this reg please?

Many thanks
Lucas

There, full guide and users applications. Also for your questions after reading at least post#1. http://www.diyaudio.com/forums/power...t-reg-pcb.html

Macronaut 12th August 2010 09:47 PM

Quote:

Originally Posted by AndrewT (Post 2269456)
there was an earlier poster who claimed that he got better sound by running the amplifying FET at a bias above it's Idss.

I disagreed then and still do now.
A jFET follower will tolerate some higher current running during signal induced high Vgs, read Curl. But there is a big downside to using a high bias at above Idss and then applying the signal induced Vgs sending current even higher.

I would much rather run the bias at 95% of Idss rather than set bias to 105% of Idss
What the B1, as proposed by Pass, does is run the FET follower at very near but not above 100% Idss.

Ah, so have I misunderstood? I thought that I had read that the conventional arrangement is for the higher Ids to serve as the CCS FET.
Perhaps I missed that in the original B1 guide. I did not do my own matching on the FET's but bought a few sets from a member source. Since I had 2 packages marked as 7.7 Ids I used those.

Salas 12th August 2010 09:58 PM

If the audio quad JFETs are very closely matched per pair its good for offset, and I recommend best match possible especially in the Blue. If tight, an average DVM will not be dependable to show 2 times which one is slightly less Idss anyway, and if you blow over or touch they will jitter. But if they have a slight and reliable difference, use the lesser one for inner position per pair.

LucasAdamson 12th August 2010 11:41 PM

Quote:

Originally Posted by Salas (Post 2270676)
There, full guide and users applications. Also for your questions after reading at least post#1. http://www.diyaudio.com/forums/power...t-reg-pcb.html

Hi Salas,

Sorry to be a pest, but I am reading and reading, but I can't find advice on specifics relating to single rail set-up anywhere. I realise that the central bar is a common earth, and that I need populate the + side only, but it's not so simple at the PS caps and rectifier diodes, which span across the two sides. Do I need to add a jumper from the - side to earth to complete the rectifier circuit?

Many thanks

Salas 13th August 2010 12:13 AM

Did you understand the setting procedure and saw a single rail T-amp project there? If yes, up to here all well, then please post your above rest of questions as new post in that thread. We will discuss it there soon, all the general reg things are there. Thanx.

ppcblaster 13th August 2010 12:35 AM

Whats the procedure to match the LED's
 
Matching the LED'S, I wire a 1.2K resistor in series with the LED apply 9vdc and measure the voltage across the LED?

Vf what's the f stand for voltage what ?

What voltage am I looking for? I ordered 40LED's and need
16, so I measure all 40 and select the 16 that measure the same
or as close to the same?

Please advise.


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