Page 1 of 20

nishant's β24+α10 integrated amp build log

PostPosted: February 28th, 2013, 9:37 pm
by tommarra
Personal rant:


I guess I should start by saying this is by far the biggest DIY project I have ever undertaken. My previous success was building an active ground B22 + S22.

So after sinking close to $1000 in parts and boards I must say I am really nervous. :roll:

I am hoping that after a few months (weeks?) I would have a fantabulous amp that will allow me to get rid of aging Arcam gear.

I am also building a pair of Jim Holtz Finalists monitors to go with the amp. But more on that later.


So here goes my builders log:

Overall approach:

Lavry DA10 -(Balanced) --> D2 --> D1 --> LCDunio --> A20 boards (4) --> B24 --> Music nirvana :mrgreen:

As of now I am planning to put all the power supplies in one box and all the other components in the other.


So Box 1 will be:

9V, 12V, 18V, 30V and 35V transformers and S25, E24, S22 for A10, B24 and S22 for B24 boards.

Hopefully a 4U Hifi dissipante box will be able to hold it and I can put it in the lowest rack of my entertainment center to keep my other electronics away from the crazy EMI its going to generate. I will use 16AWG copper wires to take care of the high current due to the distance. But that wiring decision is still a bit far off

Box 2 will be:

1 - LCDunio, 2 D2+D1, 4 A10 and 2 B24 boards.


This is the plan as of now. If evidence suggests otherwise I would separate A10 and B24 - but that would mean 4 boxes because I want to keep power supplies for both A10 and B24 to be in separate enclosures. Hopefully it wont come to that.

_____________________________________

Day 1:

Packet from AMB arrived this monday. I must say he is as good in shipping his stuff as he is in helping out clueless DIYers like me on this forum.
Mouser however too a week to deliver its part. Apparantly the LCDunio motor control chip requires export clearance and that caused the delay.

So today I finally got 2 huge boxes full of $1000 worth of parts.
mouserboxes.jpg


allcomponentsA10 -2.jpg



These parts are for A10 alone - i guess I will spread the costs and risks of failure by building B24 only after I am able to build a working A10.

If anyone needs a spreadsheet of all the parts and corresponding mouser part number - do give me a should. I have a detailed spreadsheet which lists each part number and where to buy it from (AMB for almost all transistors and Mouser for everything else).

BTW its a major pain to find the parts you need since I have close to 150 ziploc bags that mouser sent the parts in. To make it a little easier I have separated all components into 4 bags: 1. Resistors 2. Semiconductors 3. Capacitors 4. Molex and other connectors.

Atleast it makes going through AMB's partslist and finding the right parts a little bit more manageable.

______________________

Building the S25:

So I got soldering - starting with the smallest and simplest part first the S25. And after a quick trip to Radioshack, because I ran out of solderwire i bumbled my way through the soldering.

I got a scare when I checked the Resistance across AC out and DC out - AC out was fine around 7 Mohm as per amb's recommendation on the S25 page, but DC out was only 10K. I was afraid I had screwed up the soldering and blown some silicon. A quick search on this great forum revealed that 10K is indeed correct resistance and the S25 was probably fine.

So I plugged in the transformer (without the fuse - which was stupid of me) to the mains and checked that it was giving out ~10VAC, I plugged the molex onto the S25 board and was greeted with a beautiful blue glow! The thing worked! Quickly checked the voltages and it was showing at 4.97V. Let it run for a few minutes to make sure it didnt blow up.

S25 Complete.jpg

So at the end of Day 1 I now have a working S25 power supply. Small victory - but hey Rome was not built in a day!

Re: nishant's β24+α10 integrated amp build log

PostPosted: March 1st, 2013, 4:04 am
by amb
Have no fear. Looks like you're being methodical and building/testing a module at a time, which should go a long way to help you succeed.
:)

Re: nishant's β24+α10 integrated amp build log

PostPosted: March 1st, 2013, 8:00 am
by dsolodov
tommarra wrote:Personal rant:
Lavry DA10 -(Balanced) --> D2 --> D1 --> LCDunio --> A20 boards (4) --> B24 --> Music nirvana :mrgreen:

Wow, wiring β24 directly into the music nirvana bypassing speakers?

Re: nishant's β24+α10 integrated amp build log

PostPosted: March 1st, 2013, 11:23 pm
by will675
This sounds like an excellent project, I will be watching with interest (and a bucketload of envy...). Looking in the alpha10 'Other Options' section are you planning on the 'Fully-balanced, dual-mono α10 pre-amplifier' approach, without the alpha10 backboards?

I'd appreciate a copy of that spreadsheet, if you don't mind. And now you've made me aware of Jim Holtz's website that's a whole new avenue of daydreaming...

Re: nishant's β24+α10 integrated amp build log

PostPosted: March 1st, 2013, 11:36 pm
by tommarra
dsolodov wrote:
tommarra wrote:Personal rant:
Lavry DA10 -(Balanced) --> D2 --> D1 --> LCDunio --> A20 boards (4) --> B24 --> Music nirvana :mrgreen:

Wow, wiring β24 directly into the music nirvana bypassing speakers?


What can I say... I am told they are that good ;)


_________________________________________

Day 2:

Continuing the task of building the components for A10 first - today I completed the 15V - S22 power supply.

Everything progressed smoothly ....till I started soldering the 820G rectifiers. I realized that I had soldered them in the opposite direction. Had to desolder and resolder them. I was afraid that the heat generated in desoldering would fry the silicon. But a quick check after desoldering revealed that the rectifiers were fine.

The aesthetics have been marred forever though because the rectifiers are not arranged in a neat row. But thats just minor cosmetic flaw.

IMG_1286.jpeg


Other hiccup was when I realized that I didnt have a fuse to protect the circuit. Had to make a makeshift by taping copper wire to the fuse and taping it up.

IMG_1290.jpeg


Power-off sanity checks included checking resistance across AC In (approx .7M) , DC Out (~49K) and between AC and DC out (~49K).

Plugging in the AC supply, I was greeted by a blue light. Quick check of voltages and I was getting 14.97 across the two rails.


And now we have another component for the amplifier ready :-)

IMG_1288.jpeg


In case anyone is wondering why do I have a towel under the board - My standoffs are still being shipped - bought them off ebay without realizing that they are shipped from Hongkong and will take a long time to get here. Towel and the cardboard box underneath form the insulating later for the bare PCB parts.


Tomorrow is going to be a big day - LCDUnio, D1 and D2 are on the cards. There are so many ICs that I will have to be extra careful while soldering.

Re: nishant's β24+α10 integrated amp build log

PostPosted: March 2nd, 2013, 1:06 am
by amb
I guess this is stating the obvious and after the fact... but check all parts if possible (e.g., measure the resistors, check diodes, etc.) and double check orientation before soldering down anything. This is similar to what you'll be doing for the enclosure -- measure twice, cut (or drill) once.

Anyway, you can straighten the rectifiers if you're careful. Add more solder and apply heat to both PCB pads simultaneously with your soldering iron tip while gently pushing the rectifier body (use a piece of paper or something to grip the rectifier so that you don't burn your fingers). Don't overheat the PCB pads or push too hard to avoid damaging the board.

Re: nishant's β24+α10 integrated amp build log

PostPosted: March 2nd, 2013, 9:43 pm
by tommarra
amb wrote:I guess this is stating the obvious and after the fact... but check all parts if possible (e.g., measure the resistors, check diodes, etc.) and double check orientation before soldering down anything. This is similar to what you'll be doing for the enclosure -- measure twice, cut (or drill) once.

Anyway, you can straighten the rectifiers if you're careful. Add more solder and apply heat to both PCB pads simultaneously with your soldering iron tip while gently pushing the rectifier body (use a piece of paper or something to grip the rectifier so that you don't burn your fingers). Don't overheat the PCB pads or push too hard to avoid damaging the board.



Couldn't agree more - also if I may add - its important to take breaks between building - fatigue causes errors. I think I will let the rectifiers be - I dont want to risk doing something wrong and ruining the thing.



On another note - soldered the LCDuino components and now have a working pre-amp controller.

A common pitfall is that when you first turn it on there is nothing on the screen - causing a few anxious moments. But fix is as simple as turning the contrast pot all the way down (or up).

LCDuino - workig.jpg

Re: nishant's β24+α10 integrated amp build log

PostPosted: March 2nd, 2013, 9:59 pm
by amb
tommarra wrote:A common pitfall is that when you first turn it on there is nothing on the screen - causing a few anxious moments. But fix is as simple as turning the contrast pot all the way down (or up).

That's documented in the "Setup" section of the LCDuino-1 website... ;)

Re: nishant's β24+α10 integrated amp build log

PostPosted: March 2nd, 2013, 10:18 pm
by tommarra
That's documented in the "Setup" section of the LCDuino-1 website... ;)


I realized that later on - my anxiety though was caused by an error thats almost too embarrassing to document here - something to do with not being able to read + and - and almost causing S25 to blow up because of that :D

Re: nishant's β24+α10 integrated amp build log

PostPosted: March 3rd, 2013, 9:35 pm
by tommarra
Day 4:

Most of today was spend soldering the parts for D1+D2 stack. I had planned to get both the stacks done, but with my novice soldering skills and super extra ultra careful approach to checking rechecking and re-rechecking the parts before soldering is a big downer on productivity.


Good thing though is that both the D1 and D2 worked without a hitch.
D1+D2 stach.jpg

D1+D2 stach.jpg

Learnt some important lessons on the way:

1. Jumpering all the inputs and outputs in D2 takes a LONG time.
2. Hammering (okay it was hard tapping) to fit the flat cable on IDC female connector is not a good idea. Plastic breaks!


Tomorrow will be more D1 and D2.

I have couple of questions:

Question 1: About the transformer for B24 - if I build a separate power supply, do I still need a shielded encapsulated trafo from Richard Sumr or could I use a regular toroidal transformer - like this

http://www.mouser.com/ProductDetail/Tri ... 2b3PVWk%3d

This would be about $60 cheaper from Richard.

What are the disadvantages of not using a shielded encapsulated transformer if the power supply is a separate box?

Question 2:

I have also given some thought to the enclosure I want to build. I saw a build of B22 with wooden front panel - think it looks very classy.

I am planning to get two large heatsinks that will form the side, a 5mm steel plate for the botton, a 4mm backpanel from FrontPanel and a mesh for the top.

I was looking at Par-metal - they sell extruded heatsinks - anyone know if they have ones like like HiFi - Pesante type large heatsinks?

I also found www.heatsinkusa.com - does anyone have any experience with them?