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

PostPosted: March 8th, 2013, 10:49 am
by tommarra
MisterX wrote:alt 224 = α
alt 225 = ß


Thanks MisterX and Do



One more question: is there any benefit of using shielded wire (e.g Johns teflon shielded wire) for audio signal?

http://item.mobileweb.ebay.com/viewitem ... 0551850150

What would be a good wire gauge for input and output to both A20 and B24?

I am thinking 22 gauge shielded for A20 boards and a 16 gauge for B24 output.

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

PostPosted: March 8th, 2013, 12:21 pm
by amb
Shielded wire is good for input and low-signal paths. If the wire run is short, you can use non-shielded wires and twist the signal and ground wires together to improve noise rejection. Since there is negligible current, thin wires are fine (22-24 AWG).

For speaker output and power wiring I used non-shielded 16 AWG stranded wires (within the chassis). If these runs are long then I would use even thicker wires.

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

PostPosted: March 8th, 2013, 2:37 pm
by tommarra
Thanks for the answering the question about the wiring.



On another note:
Now that A10 is complete, I have been thinking about my enclosure design for the past couple of days and a few things are aparant to me now:

1. HiFi cases for my 2 box design is way too expensive - it will come to something like $500 incl shipping - so that leaves it out of the equation and means I will have to make one up from scratch.
2. The largest heatsinks I can find are 10 inch from Heatsink USA - so that limits my design to 10 inch depth.
Based on these challenges I have come up with the board layout of my box. Key criteria for the layout were - reduce the audio signal wire length esp from input connectors to D1/D2 and from the D1/D2 to A20 and forward to B24.

So I have three potential layouts and would like feedback on them.

Height would be 7 inch.

Layout 1:

Slide1.JPG

I dont particularly like this design because this would mean that the motorized pot would overlap the A20 board and I am worried that the motor in the pot might create issues esp when changing the volume.

Layout 2:
Slide2.JPG

I am not sure what would be the impact of stacking two A20 boards. I have a tall enough design so I can space the two with enough separation and the silicon doesnt run too hot anyhow.

Layout 3:
B24 Design.jpg

In this layout I have a lot of open space so I could either stack the A20 boards or lay them out separately. Also this gives me the flexibility of moving the A20 boards towards the center in case 1.5 inch is not enough headroom for B24 boards with the large capacitors (BTW what is the height of a completed B24 board?).
Also this layout theoretically gives most separation of audio signal path from other components (LCD, Pot switches etc.)

Which one is the most preferred.

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

PostPosted: March 8th, 2013, 5:30 pm
by dsolodov
Here is another option for the caps... Mouser sell Epcos clamps for these caps.http://item.mobileweb.ebay.com/viewitem?itemId=271168450145&index=0&nav=SELLING&nid=56745879885

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

PostPosted: March 8th, 2013, 6:29 pm
by dsolodov
The reason for Sikorel (or Elna) vs 'industrial' caps from TNT audio:
A typical commercial value capacitor, rated at 10,000uF/63V and costing some Euro 8-9, will have a speed of 30-40V/uS at best. An equivalent Elna for Audio series black, costing some Euro 15-25, will have a speed in the range of 80-90V/uS, i.e. at the very worst, double the speed of the best case in commercial cap land. A Siemens Sikorel cap, costing some Euro 20-30, will slew at over 100V/uS - but at a price.

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

PostPosted: March 8th, 2013, 6:56 pm
by dsolodov
tommarra wrote:Thanks for the answering the question about the wiring.



On another note:
Now that A10 is complete, I have been thinking about my enclosure design for the past couple of days and a few things are aparant to me now:

1. HiFi cases for my 2 box design is way too expensive - it will come to something like $500 incl shipping - so that leaves it out of the equation and means I will have to make one up from scratch.
2. The largest heatsinks I can find are 10 inch from Heatsink USA - so that limits my design to 10 inch depth.
Based on these challenges I have come up with the board layout of my box. Key criteria for the layout were - reduce the audio signal wire length esp from input connectors to D1/D2 and from the D1/D2 to A20 and forward to B24.

So I have three potential layouts and would like feedback on them.

Height would be 7 inch.

Layout 1:

Slide1.JPG

I dont particularly like this design because this would mean that the motorized pot would overlap the A20 board and I am worried that the motor in the pot might create issues esp when changing the volume.

Layout 2:
Slide2.JPG

I am not sure what would be the impact of stacking two A20 boards. I have a tall enough design so I can space the two with enough separation and the silicon doesnt run too hot anyhow.

Layout 3:
B24 Design.jpg

In this layout I have a lot of open space so I could either stack the A20 boards or lay them out separately. Also this gives me the flexibility of moving the A20 boards towards the center in case 1.5 inch is not enough headroom for B24 boards with the large capacitors (BTW what is the height of a completed B24 board?).
Also this layout theoretically gives most separation of audio signal path from other components (LCD, Pot switches etc.)

Which one is the most preferred.

It would be interesting to see the spectrum analysis of each power supply at the connection point to the supplied component as well as audio output in the above setup options. I sense unless one shields EMI of each of the power supply 'lines' separately they will feed from each other along with high frequencies of i2c to the driver boards.

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

PostPosted: March 8th, 2013, 8:06 pm
by tommarra
dsolodov wrote:It would be interesting to see the spectrum analysis of each power supply at the connection point to the supplied component as well as audio output in the above setup options. I sense unless one shields EMI of each of the power supply 'lines' separately they will feed from each other along with high frequencies of i2c to the driver boards.



Sorry, I am not quite sure I follow you :-(

I do not have any advanced equipment to do any advanced measurements - hence i was asking for feedback on the layout.

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

PostPosted: March 8th, 2013, 9:40 pm
by amb
It's ok to stack the α20 boards, but it would make it hard to make adjustments to the trimpots on the lower board, unless you remove the top one.

The driver section of the δ1/δ2 boards contain digital circuitry, especially at the J1 end. It's best not to place audio circuitry right next to it.

The height of the 2200uF electrolytic caps or the DN2535 MOSFET heatsinks will typically determine the maximum height of the board, whichever is taller.

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

PostPosted: March 9th, 2013, 12:13 am
by amb
By the way, although Hifi2000/Modushop cases are nice, there are alternatives out there. For example, check out SiliconRay (front page > Audio > Enclosures & Chassis). I have no affiliation or personal experience with this company, just passing some info along.

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

PostPosted: March 9th, 2013, 3:33 am
by Shaman
Yeap, I have spent some serious $$$$ on Modushop enclosures in the past but I'm now shopping from Siliconray.
Enclosure quality is good to excellent (depending on enclosure type), plus they can make custom sizes (for minimum quantities) and can even take on CNC work, all for very good prices.