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The Multi Amp aka Dynalo Mk2


spritzer

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My Iron felt like the life was getting sucked out of it towards the end battling with the ground plane...
I need to sort out how best to attach the heatsinks for the output transistors, a nice non conductive thermal tape of sorts, double sided... for the hopeful.
Otherwise my first mini dynalo is working... although I have no dynamic phones to verify:lol:.

For the chassis I’m going for modushop 40mm side flanges, other panels will be 2mm thick from FPE, black anodised I’m thinking.

Amazing job Kerry thank you so much for the mini design.

IMG_1185_zpspoyyoete.jpg

Edited by johnwmclean
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here is a dxf file that is modified, https://drive.google.com/open?id=0BwUlR99qUHFqQnVZcGkzMjBva3c

I enlarged it .250" to allow for 1/4" square stock to use as a frame

and made other minor changes, its not perfect yet but getting close.

RCA hole size increased to fit the lip around them.

the IEC corners have been rounded more but haven't tested that

also want a round button instead of the square one

 test pieces out of PCB

IMG_20170206_222324057.jpg

bck-38_HDR.jpg

 

2381_HDR.jpg

and yes I cheated on the trimpots

and I find these very hard to solder:

88097.jpg

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Here are the original ones from Kerry, don't think he will mind..

https://drive.google.com/open?id=0BwUlR99qUHFqY1YxRjFfcnA1X1k

1 hour ago, johnwmclean said:

nice work, impressive soldering.

Well that was after several hours of trial and error, next time I should just order the prebuilt ones.

Kerry thanks for the beautiful layout, files, schematics and advice.

This was quite different from the norm,  a nice adventure.

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Old wine in a new bottle - just finished casing mySS Dynalo today.

Dual mono setup - one Antek 25va transformer and one 20VDC GoldenReference for each channel. Just over 14mA current on each output device (MPSWx6).

First built this SS Dynalo back in 2014. Every time I took a break from my ES setup to listen to this amp I am amazed how much I like its sound. Wish I had the chance to listen to the top Focal headphones with this amp... 

SS Dynalo - front.JPG

SS Dynalo - rear.JPG

SS Dynalo - inside.JPG

SS Dynalo - front 5.JPG

Edited by mwl168
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15 hours ago, mypasswordis said:

Where did you find a screw long enough for both, and I assume no hum or anything?

Found the perfect length (8cm IIRC) screw at ACE Hardware. Got lucky! I screwed the bottom transformer down first with the supplied pads and washers and then stacked the second one on top. It's very secure.

I laid out the components (PS, amp boards, transformers, XLR sockets) with the objective to keep the transformers and ac wires as far away as possible from the input wire and the amp boards. 

No buzz no hum that I can detect:)

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22 minutes ago, masamoto said:

Other than losing the GRLV is there any compromise by going mini?

The mini uses 16 transistors per channel whereas the full size uses 24. I would presume that the mini has a lower power output as a result. You also lack the freedom of the kind of attenuator you would like to use, but you can get around that by going offboard and connecting with wires.

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6 minutes ago, cspirou said:

The mini uses 16 transistors per channel whereas the full size uses 24. I would presume that the mini has a lower power output as a result. You also lack the freedom of the kind of attenuator you would like to use, but you can get around that by going offboard and connecting with wires.

 
 

Ah, ok thanks. :) I Pulled out the schematics for both now to look at some differences. Just general curiosity.

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I'm pretty sure that the full size also uses 16 output devices, unless there is another version I'm not familiar with.

The amp circuits should be identical in both.

The power supply is the main difference since I'm using a switching supply followed by TI regulators (which are very good in their own right).

 

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Just looking at kgdynalobal9.zip I count 22, so it's not 24 but still more then 16.

Of course this is just counting the transistors themselves and not based on the schematic so I can't say that they are all used for the output. I need to take a closer look at the schematic to verify.

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