The Multi Amp aka Dynalo Mk2

[Kerry]

That's why I put the 0 ohm resistors in

[JoaMat]

Very much appreciated.

[johnwmclean]

 

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.

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.

Edited February 18, 2017 by johnwmclean

[johnwmclean]

delete me

Edited February 18, 2017 by johnwmclean

[Pars]

Very clean soldering work John! Nice!

Did you do any matching?

Edited February 18, 2017 by Pars

[Kerry]

Very nice John!

I have dxf files for the front and back plates.  I'll see if I can get them published.

Edited February 18, 2017 by Kerry

[congo5]

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

 

and yes I cheated on the trimpots

and I find these very hard to solder:

[johnwmclean]

22 hours ago, Pars said:

Did you do any matching?

No matching. The offset without servos engaged is ~ 0 - 2 mV per phase, which I'm pretty happy with.

Congo5, very nice work, impressive soldering.

Thanks for the dxf file guys.

 

[congo5]

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.

[mwl168]

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... 

Edited February 25, 2017 by mwl168

[Pars]

Looks nice Michael! Only a 25VA transformer? I guess it is 700mA per secondary,

[Skooby]

Just finished my Dynalo Mini today.  Sounds fantastic (GS-X in a palm)!  Many thanks to KG and Kerry for the design/gerber files and Steve for setting up the group buy!

  

[Kerry]

Looks good. 

Just a couple of safety thoughts.  You should try to put the fuse holder with fuse back in.  Also, I'm not sure if you've tied the chassis to earth, but you should do that too.

Nice looking chassis. 

Enjoy

[mwl168]

7 hours ago, Pars said:

Looks nice Michael! Only a 25VA transformer? I guess it is 700mA per secondary,

Thanks Chris!

Two 25VA transformers stacked - one for each channel

Edited February 26, 2017 by mwl168

[rumina]

these two amps are nice. the rounded case looks verry modern, like the idea of a dual power supply.

[mypasswordis]

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

[jose]

I always have dudes when I use two PSU. I don't know how connect the grounds.

[mwl168]

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

[mdr30]

Humbuckers, wire'm outa phase, he-he.

[Kerry]

I've updated the mini board to use the TDK 4CP601.

Here's the gerber files zipped up.  Just rename the .pdf file back to .zip to open it.

SuperSymmetryDynalo-TDK-v1-5.pdf

I'll send it to Kevin to publish as well.

[masamoto]

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

[cspirou]

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.

[masamoto]

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.

[Kerry]

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).

 

[cspirou]

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.